WO2025170076A1 - Three-dimensional molded insulator and method for manufacturing three-dimensional molded insulator - Google Patents

Abstract

The present invention provides a three-dimensional molded insulator that enables reduction of dead space between a circuit board and the three-dimensional molded insulator, thereby enabling effective use of a space in which the circuit board is accommodated, and a method for manufacturing a three-dimensional molded insulator, the method enabling the manufacture of a three-dimensional molded insulator having high shape accuracy. This three-dimensional molded insulator covers a component to which a voltage is applied and is characterized by: being formed into a shape with a recess portion including a bottom portion and a wall portion provided at an end of the bottom portion; and being used in a state in which a component is inserted into the recess portion.

Description

Three-dimensionally formed insulator and method for manufacturing the same

The present invention relates to three-dimensionally formed insulators and methods for manufacturing three-dimensionally formed insulators.

Electronic devices house circuit boards that include a substrate and various voltage-applied components mounted on the substrate. A certain insulation distance is maintained around such circuit boards to prevent electrical short circuits.

For example, Patent Document 1 discloses a flame-retardant resin composition made by blending polycarbonate resin, a phosphate ester compound, and a fibrous material. It also discloses an insulating sheet made by molding this flame-retardant resin composition into a sheet. Insulating sheets are useful because they can be stored in narrow gaps within electronic devices. By placing an insulating sheet between a conductor present around a circuit board, for example, it is possible to shorten the insulation spatial distance.

Japanese Patent Application Laid-Open No. 2002-030209

However, because the height (thickness) of voltage-applied components is not uniform, the thickness of the circuit board varies accordingly. Conventional insulating sheets are flat, so they are positioned to fit the tallest voltage-applied component. This creates the problem of large dead spaces between the board and the insulating sheet (around the voltage-applied component). This dead space is one of the factors that hinder the miniaturization of electronic devices.

Furthermore, shortening the insulating spatial distance around voltage-applied components, not just circuit boards, can contribute to the miniaturization of electronic devices.

The object of the present invention is to provide a three-dimensional molded insulator that can reduce the dead space that occurs around voltage-applied components and enable effective use of the space in which the voltage-applied components are housed, as well as a method for manufacturing three-dimensional molded insulators that can produce three-dimensional molded insulators with high shape accuracy.

These objects can be achieved by the present invention described in (1) to (12) below.
(1) A three-dimensionally shaped insulator that is placed over a component to which voltage is applied,
The container is molded into a shape having a recess including a bottom and a wall portion provided at an end of the bottom,
A three-dimensionally molded insulator characterized in that the component is inserted into the recess when used.

(2) The device is used by covering a circuit board including the component and a board on which the component is mounted,
The three-dimensionally molded insulator according to (1) above, which is molded into a shape having the recess and a flat portion connected to the recess.

(3) A three-dimensionally molded insulator as described in (2) above, having a through hole penetrating the flat portion in the thickness direction.

(4) A three-dimensionally molded insulator as described in (3) above, wherein the thickness of the wall portion is 20% or more and 95% or less of the thickness of the flat portion.

(5) The three-dimensionally molded insulator according to (3) or (4) above, wherein the thickness of the flat portion is 0.05 mm or more and 1.00 mm or less.
(6) The three-dimensionally molded insulator according to any one of (1) to (4) above, which contains a flame retardant.

(7) A three-dimensionally molded insulator according to any one of (1) to (4) above, whose main material is a thermoplastic resin.

(8) A three-dimensionally molded insulator according to (7) above, wherein the thermoplastic resin includes an aromatic polycarbonate resin.

(9) A three-dimensionally molded insulator according to any one of (1) to (4) above, having a comparative tracking index (CTI), an index of tracking resistance measured in accordance with ASTM D3638, of 600 V or more.

(10) A three-dimensionally molded insulator according to any one of (1) to (4) above, whose flame retardancy measured in accordance with the UL94 standard is V-0 or VTM-0 for a test specimen with a thickness of 0.4 mm or more.

(11) A method for producing the three-dimensionally molded insulator according to any one of (1) to (4) above,
A method for manufacturing a three-dimensional molded insulator, characterized in that a flat thermoplastic insulating sheet is subjected to secondary processing including thermoforming to form the recesses.

(12) A method for producing a three-dimensionally molded insulator as described in (11) above, in which the thermoforming is vacuum forming or vacuum-pressure forming.

According to the present invention, a three-dimensionally molded insulator can be obtained that can reduce the dead space that occurs around voltage application components and enable effective use of the space in which the voltage application components are housed.
Furthermore, according to the present invention, it is possible to manufacture a three-dimensionally molded insulator with high shape accuracy.

FIG. 1 is a perspective view showing a three-dimensionally shaped insulator according to an embodiment and a circuit board on which the three-dimensionally shaped insulator is to be placed. FIG. 2 is a cross-sectional view of the circuit board shown in FIG. 1 taken along line AA. FIG. 3 is a cross-sectional view showing only the three-dimensionally shaped insulator of FIG. FIG. 4 is a cross-sectional view showing a modification of the circuit board of FIG. FIG. 5 is a top view showing a three-dimensionally shaped insulator according to a modified embodiment. FIG. 6 is a cross-sectional view of the busbar and three-dimensionally shaped insulator shown in FIG. FIG. 7 is a cross-sectional view showing a three-dimensionally shaped insulator according to a modified example. FIG. 8 is a cross-sectional view showing a control device in which the three-dimensionally molded insulator and the circuit board according to the embodiment are housed in a case. FIG. 9 is a cross-sectional view showing a modification of the control device of FIG.

The three-dimensionally molded insulator and the method for manufacturing the three-dimensionally molded insulator according to the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

1. Overview of Three-Dimensional Molded Insulator FIG. 1 is a perspective view showing a three-dimensionally shaped insulator 1 according to an embodiment and a circuit board 9 on which the three-dimensionally shaped insulator 1 is to be placed. Note that FIG. 1 illustrates the state before the three-dimensionally shaped insulator 1 is placed on the circuit board 9. In addition, in each drawing of the present application, three mutually orthogonal axes are set as an X-axis, a Y-axis, and a Z-axis, and each axis is indicated by an arrow. Furthermore, the base end side of the arrow is referred to as the negative side of each axis, and the tip end side is referred to as the positive side of each axis. Furthermore, the positive side of the Z-axis is referred to as "upper," and the negative side of the Z-axis is referred to as "lower."

As shown in FIG. 1, the three-dimensional molded insulator 1 is used, for example, by covering a circuit board 9. The circuit board 9 includes a wiring board 90 having wiring (not shown), a power semiconductor element 91, a bus bar 92, a signal connector 93, and a fixing screw 94. Of these, the power semiconductor element 91, the bus bar 92, the signal connector 93, and the fixing screw 94 each protrude upward from the top surface of the wiring board 90. The power semiconductor element 91 and the bus bar 92 are used under a relatively high voltage. The applied voltage is, for example, 50 V or more, and preferably 71 V or more and 10 kV or less. By covering the circuit board 9 with the three-dimensional molded insulator 1 from above, the insulation between the circuit board 9 and other objects (not shown) placed above it can be improved. This reduces the spatial distance required for insulation between the circuit board 9 and other objects.

Furthermore, as shown in FIG. 1, the three-dimensionally molded insulator 1 is three-dimensionally molded into a shape having a recess 12, more specifically, a shape having a flat portion 11 and a recess 12. Three-dimensional molding refers to molding a sheet-like member into a shape having a recess that is deeper than the thickness of the member. When viewed in a plan view from the Z axis, the insulating sheet 1 has an outer size and shape that overlaps with the wiring board 90. The flat portion 11 is a portion having a flat surface 110 that is parallel to the upper surface of the wiring board 90. The flat surface 110 is the lower surface of the flat portion 11 that faces the upper surface of the wiring board 90. Note that an angular deviation of 10 degrees or less is allowed in this parallelism. The recess 12 is a portion that is recessed upward from the flat surface 110. The position of the recess 12 in a plan view is aligned with the positions of the power semiconductor element 91, bus bar 92, and signal connector 93 arranged on the wiring board 90.

When the three-dimensional molded insulator 1 is placed over the circuit board 9, the power semiconductor element 91, bus bar 92, and signal connector 93 are inserted into the recess 12. This allows the top and side surfaces of these components that protrude from the top surface of the wiring board 90 to be covered with the three-dimensional molded insulator 1. As a result, only a minimal gap is created between the circuit board 9 and the three-dimensional molded insulator 1, reducing dead space compared to conventional methods. In other words, the dead space around components to which voltage is applied, such as the power semiconductor element 91, bus bar 92, and signal connector 93, can be reduced. This makes it possible to effectively utilize the space that houses the circuit board 9.

Therefore, by using the three-dimensionally molded insulator 1, it is possible to miniaturize the equipment on which the circuit board 9 is mounted. Note that the orientation of the three-dimensionally molded insulator 1 when in use (its orientation relative to the vertically upward direction) is not limited to the above. For example, if the upper surface of the above-mentioned wiring board 90 faces downward, the three-dimensionally molded insulator 1 will be placed over the wiring board 90 from below. In this case, the above-mentioned recess 12 will be a portion that is recessed downward from the flat surface 110.

2. Circuit Board Prior to describing the three-dimensionally shaped insulator 1, a detailed description will be given of the circuit board 9. The circuit board 9 is not particularly limited as long as it has a configuration including a substrate and components that protrude from the surface of the substrate and to which a voltage is applied.

As described above, the circuit board 9 shown in FIG. 1 includes the wiring board 90, the power semiconductor element 91, the bus bar 92, the signal connector 93, and the fixing screw 94.
FIG. 2 is a cross-sectional view of the circuit board 9 shown in FIG. 1 taken along line AA.

As shown in Figure 2, the wiring substrate 90 has an insulating layer 901, a wiring layer 902, through-hole wiring 903, and thermal vias 904.

The power semiconductor elements 91 are semiconductor elements that perform high-power switching and the like. Examples of power semiconductor elements 91 include IGBTs (insulated gate bipolar transistors) and power MOSFETs (metal-oxide semiconductor field-effect transistors). Figure 1 shows six power semiconductor elements 91, each protruding upward from the top surface of the wiring board 90. Each power semiconductor element 91 is in contact with a thermal via 904, allowing heat dissipation.

The bus bar 92 is a conductor that connects the circuit board 9 and the power supply. The bus bar 92 is made of, for example, a metal plate or rod. The bus bar 92 shown in FIG. 2 protrudes upward from the top surface of the wiring board 90 and is bent sideways (towards the negative X-axis) midway. The bus bar 92 is electrically connected to the wiring board 90 via through-wires 903. The bus bar 92 shown in FIG. 1 includes bus bars 921 and 922, which have currents flowing in opposite directions.

The signal connector 93 is a connector into which a signal line is inserted. The signal line is used, for example, to send and receive signals between the circuit board 9 and an external control device. The signal connector 93 protrudes upward from the top surface of the wiring board 90.

The fixing screws 94 penetrate the four corners of the wiring board 90 in the thickness direction. The fixing screws 94 secure the wiring board 90 to a housing or the like (not shown). The heads of the fixing screws 94 protrude upward from the top surface of the wiring board 90.

In the circuit board 9 described above, voltage is applied to the power semiconductor elements 91, bus bars 92, and signal connectors 93. Since high voltages are applied to the power semiconductor elements 91 and bus bars 92 in particular, insulation using the three-dimensional molded insulator 1 is effective.

Note that the components to which voltage is applied are not limited to those listed above, and may be any component to which voltage is applied. Specific examples other than those listed above include batteries, capacitors, diodes, coils, resistors, relays, transformers, switches, connectors, terminals, etc.

In addition, even if a voltage is not directly applied to a component, components that are in contact with a component to which the voltage is directly applied may also be subject to the unintentional application of voltage, and are therefore considered to be included in the "components to which voltage is applied." Examples of such components include heat sinks, heat spreaders, and heat pipes.

3. Configuration of Three-Dimensional Molded Insulator Next, the configuration of the three-dimensionally molded insulator 1 will be described.

3.1 Shape of the Three-Dimensional Molded Insulator As described above, the three-dimensionally molded insulator 1 shown in Fig. 1 has a plurality of recesses 12 that correspond to components protruding from the upper surface of the wiring board 90. The recesses 12 are open downward. The three-dimensionally molded insulator 1 is used with each component inserted through the openings.

Such recess 12 includes recess 121 into which power semiconductor element 91 is inserted, recess 122 into which bus bar 92 is inserted, and recess 123 into which signal connector 93 is inserted. Recesses 121, 122, and 123 are each molded to match the external size and shape of the inserted component. This minimizes the gap between each component and recess 121, 122, and 123, thereby reducing dead space. In other words, because the area of recesses 121, 122, and 123 in plan view can be minimized, the area of flat portion 11 can be maximized accordingly. This allows for more effective use of the space above flat portion 11 (the space around the component to which voltage is applied) than when using a conventional flat insulating sheet.

Furthermore, the recesses 12 cover not only the top surfaces of each component but also the side surfaces. This prevents dust and other foreign matter from adhering to the side surfaces of each component, and prevents moisture and other substances from being adsorbed.

Furthermore, terminals and the like may be exposed on the side of each component. The recess 12 also effectively insulates such terminals. For example, the provision of the recess 12 makes it possible to shorten the spatial distance L1 required for insulation between the bus bar 92 and the power semiconductor element 91 shown in Figure 2 (the spatial distance required for insulation between components). This makes it possible to reduce the size of the circuit board 9.

FIG. 3 is a cross-sectional view showing only the three-dimensionally shaped insulator 1 of FIG.
The recess 12 shown in Fig. 3 includes a bottom 12a and wall portions 12b. The bottom 12a is a portion that covers the upper surfaces of the power semiconductor elements 91 and the bus bars 92. The wall portions 12b are portions that rise down from the end of the bottom 12a and cover the side surfaces of the power semiconductor elements 91 and the bus bars 92. The shapes of the bottom 12a and the wall portions 12 are not limited to the shapes shown in Fig. 3. The connection portion between the bottom 12a and the wall portions 12b may be rounded or chamfered.

Furthermore, by molding the recess 12 to an appropriate size and shape, the separation distance S2 between the inner surface of the recess 12 and components such as the power semiconductor element 91, as shown in Figure 2, can be made sufficiently close. This makes it possible to more effectively reduce dead space and effectively protect the side surfaces of each component.

The separation distance S2 is not particularly limited, but is preferably 10 mm or less, more preferably 7 mm or less, and even more preferably 5 mm or less. This allows dead space to be sufficiently reduced and each component to be protected more effectively. As will be described later, the three-dimensional molded insulator 1 has good tracking resistance. Therefore, even if the separation distance S2 is within the above range, tracking is unlikely to occur. On the other hand, when taking into consideration the efficiency of heat dissipation from the components, stress on the components, ease of assembly, etc., the separation distance S2 is preferably 0.5 mm or more, and more preferably 1 mm or more.

Furthermore, although not shown, the distance between the ceiling surface of the recess 12 and components such as the power semiconductor element 91 is the same as the above-mentioned distance S2.

On the other hand, by forming the recess 12 to an appropriate size and shape, the separation distance S1 between the flat surface 110 of the flat portion 11 and the wiring board 90, as shown in Figure 2, can be made sufficiently close. Furthermore, by reducing the separation distance S1, it becomes easier to prevent foreign matter such as dust from adhering to the upper surface of the wiring board 90, and moisture from being adsorbed. This also makes it easier to prevent creeping discharge and subsequent tracking that occurs between the bus bar 92 and the power semiconductor element 91.

The separation distance S1 is not particularly limited, but is preferably 15 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. This allows the dead space to be sufficiently reduced. Furthermore, in the example shown in Figure 2, by keeping the separation distance S1 within the above range, the probability of the three-dimensional molded insulator 1 being interposed between the power semiconductor element 91 and the bus bar 921 increases, and the three-dimensional molded insulator 1 can be brought sufficiently close to the wiring board 90 between them. This makes it possible to suppress creeping discharge and tracking that occur between them, and to sufficiently shorten the spatial distance L1 required between them.

The recess 12 includes recesses 121 into which the power semiconductor elements 91 are inserted one by one. This allows each power semiconductor element 91 to be protected individually. It also reduces the distance required for insulation between the power semiconductor elements 91. Note that the recess 121 may be configured to accommodate the insertion of two or more power semiconductor elements 91 (components).

The recess 12 includes recesses 122 into which the bus bars 921, 922 are inserted one by one. This allows the bus bars 921, 922 to be protected individually. It also reduces the distance required for insulation between the bus bars 921, 922. Note that the recess 122 may be configured to accommodate the insertion of two or more bus bars 92 (components).

Furthermore, in the circuit board 9 shown in FIG. 1, the bus bars 921 and 922 are aligned along the Y axis. However, the bus bars 921 and 922 may be configured to partially overlap along the Z axis.

FIG. 4 is a cross-sectional view showing a modification of the circuit board 9 of FIG.
In FIG. 4 , bus bar 921 and bus bar 922 partially overlap along the Z axis. In this portion, positive and negative currents flow closely together. As a result, magnetic fluxes generated by the currents cancel each other out, reducing the inductance component. Therefore, the configuration shown in FIG. 4 can achieve a circuit board 9 with a reduced inductance component in bus bar 92. This can reduce surge voltages on circuit board 9.

Furthermore, a three-dimensional molded insulator 1 is interposed between busbar 921 and busbar 922. This prevents dielectric breakdown and other problems even when busbars 921 and 922 are placed sufficiently close to each other. As a result, the inductance component can be reduced more effectively.

Furthermore, in the example of Figure 4, the side surface of bus bar 921 on the positive side of the X axis and the side surfaces on the positive and negative sides of the Y axis (not shown in Figure 4) are covered by the inner surface of recess 122. Therefore, even if bus bars 921 and 922 are brought sufficiently close to each other, creeping discharge can be effectively suppressed.

Figure 5 is a top view showing a three-dimensionally molded insulator 1 according to a modified embodiment. Figure 6 is a cross-sectional view of the busbar 92 and three-dimensionally molded insulator 1 shown in Figure 5.

The three-dimensionally molded insulator 1 shown in Figure 5 is a modified example of the three-dimensionally molded insulator 1 shown in Figure 3, and is provided, for example, at a position away from the circuit board 9. Specifically, the bus bars 921, 922 shown in Figure 4 may protrude from the wiring board 90 and extend toward the negative X-axis side. The three-dimensionally molded insulator 1 shown in Figure 5 is preferably used in the extended portions of the bus bars 921, 922.

The bus bars 921 and 922 shown in Figure 5 correspond to the extensions described above. In the extensions, the bus bars 921 and 922 overlap each other along the Z axis. In the overlapping portion, the bottom 12a of the three-dimensionally shaped insulator 1 is positioned between the bus bars 921 and 922. In addition, the wall 12b of the three-dimensionally shaped insulator 1 shown in Figure 5 rises from the end of the bottom 12a toward the positive side of the Z axis, as shown in Figure 6. As a result, the side surface of the bus bar 922 is covered by the wall 12b.

With this configuration, the three-dimensionally molded insulator 1 shown in Figures 5 and 6 can reduce the dead space around the bus bar 922. In other words, by providing the wall portion 12b, the insulating spatial distance on the sides of the bus bar 922 can be reduced, making it possible to place any component on the side of the bus bar 922. This makes it possible to reduce the space that would previously have been dead space.

Furthermore, because the three-dimensionally molded insulator 1 shown in Figure 5 is used with the bus bar 922 inserted into the recess 12, misalignment between the bus bar 922 and the three-dimensionally molded insulator 1 is suppressed. Therefore, even if vibrations or the like are applied, the three-dimensionally molded insulator 1 can be prevented from falling off or the like.

The three-dimensionally molded insulator 1 shown in Figure 1 also has a through hole 13 that penetrates the flat portion 11 in the thickness direction. The through hole 13 is provided to match the position of the fixing screw 94. By providing the through hole 13, the fixing screw 94 can be rotated even when the three-dimensionally molded insulator 1 is placed over the circuit board 9. This makes it possible to screw the circuit board 9 to a case or the like with the three-dimensionally molded insulator 1 placed over the circuit board 9, improving assembly workability. In this case, it is preferable that the inner diameter of the through hole 13 is equal to or greater than the outer diameter of the head of the fixing screw 94. This makes it easier to rotate the fixing screw 94.

In addition, when the fixing screw 94 is tightened against the circuit board 9, the head of the fixing screw 94 may be positioned above the three-dimensionally shaped insulator 1. This allows the fixing screw 94 to fix the three-dimensionally shaped insulator 1 together with the circuit board 9. In this case, it is preferable that the inner diameter of the through hole 13 is smaller than the outer diameter of the head of the fixing screw 94.

Furthermore, the planar shape of the through hole 13 is not limited to a closed shape, but may also be a shape with a portion open outward.

The thickness t11 of the flat portion 11 of the three-dimensionally molded insulator 1 is not particularly limited, but is preferably 0.05 mm or more and 1.00 mm or less, more preferably 0.10 mm or more and 0.90 mm or less, and even more preferably 0.20 mm or more and 0.80 mm or less. This results in a three-dimensionally molded insulator 1 that is excellent in flame retardancy, tracking resistance, and insulation, and is relatively easy to manufacture. Note that if the thickness t11 of the flat portion 11 is below the lower limit, there is a risk of reduced flame retardancy, tracking resistance, and insulation. On the other hand, the thickness t11 of the flat portion 11 may exceed the upper limit, but in that case, the three-dimensionally molded insulator 1 may be too thick, reducing flexibility and making handling difficult, reducing heat dissipation and shape accuracy, and increasing the difficulty of manufacturing.

Furthermore, the thickness t12b of the wall portion 12b is preferably 20% to 95% of the thickness t11 of the flat portion 11, more preferably 30% to 90%, and even more preferably 50% to 90%. If the thickness t12b of the wall portion 12b is within this range, it will have sufficient rigidity to support the shape of the recess 12 and will further reduce the dead space on the sides of the recess 12.

If the thickness t12b of the wall portion 12b is below the lower limit, the rigidity of the wall portion 12b may be insufficient. On the other hand, if the thickness t12b of the wall portion 12b exceeds the upper limit, the effect of reducing the dead space on the sides of the recess 12 may be reduced.

Note that the external shape of the three-dimensional molded insulator 1 shown in Figure 1 is, as an example, a shape that overlaps the entire circuit board 9, but it may be smaller or larger than this.

Furthermore, it is preferable that the recess 12, like recess 121, cover the entire side surface of the component protruding from the top surface of the wiring board 90, but it may also cover only part of the side surface of the component, like recesses 122 and 123, for example.

The depth of the recess 12 is set according to the height of the component, so is not particularly limited, but may be between 0.5 mm and 100 mm, or between 1 mm and 50 mm. Within these ranges, a three-dimensional molded insulator 1 can be realized that is easy to manufacture and has recesses 12 into which various components can be inserted with almost no height restrictions.

3.2. Materials for Constituting the Three-Dimensional Molded Insulator Next, the materials for constituting the three-dimensionally molded insulator 1 will be described.

The three-dimensionally molded insulator 1 contains, for example, a resin material. The proportion of resin material in the constituent materials of the three-dimensionally molded insulator 1 is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. This results in a three-dimensionally molded insulator 1 that has excellent insulating properties and formability, and is easily lightweight.

Examples of resin materials include various thermoplastic resins such as polyolefin resin, polyamide resin, polyester resin, aromatic polycarbonate resin, aliphatic polycarbonate resin, polyarylate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polylactic acid, styrene copolymer, polyacetal resin, polyphenylene ether resin, polyphenylene sulfide resin, polymethyl methacrylate resin, and cellulose ester resin, as well as various thermosetting resins such as polyimide, polyurethane, epoxy resin, and phenolic resin. The first resin and the second resin may be a combination of one or more of these resins.

Furthermore, it is preferable that the three-dimensionally molded insulator 1 be primarily made of thermoplastic resin. "Main material" refers to the above-mentioned proportions. Sheets primarily made of thermoplastic resin are capable of plastic deformation due to heat, and have excellent secondary processability. For this reason, a three-dimensionally molded insulator 1 can be produced by thermoforming, resulting in a product that is easy to manufacture.

Among these, polyolefin resins, polyamide resins, aromatic polycarbonate resins, and aliphatic polycarbonate resins are preferably used as thermoplastic resins.

Furthermore, resin materials with high tracking resistance are preferably used. Tracking resistance refers to resistance to the phenomenon in which a conductive path (tracking) is formed due to discharge that occurs on the surface of an insulator. Such tracking resistance can be quantified, for example, by the comparative tracking index (CTI), which is an indicator of tracking resistance measured in accordance with ASTM D3638.

The comparative tracking index CTI of the resin material is preferably 400 V or higher, and more preferably 600 V or higher. This results in a three-dimensional molded insulator 1 with particularly good tracking resistance.

The glass transition temperature Tg of the resin material is preferably 125°C or higher, and more preferably 130°C or higher but lower than 200°C. This gives the resin material heat resistance, making it easier to suppress discoloration due to carbonization, even if creeping discharge occurs in the three-dimensional molded insulator 1. As a result, the occurrence of poor appearance in the three-dimensional molded insulator 1 and the deterioration of insulation properties due to carbonization can be suppressed. The glass transition temperature Tg of the resin material is measured using a differential scanning calorimeter (DSC) method. The heating rate in the DSC method is 10°C/min.

The melt volume rate (MVR) of the resin material at 300°C and a load of 1.2 kg is preferably 5 cm ³ /10 min or more and 30 cm ³ /10 min or less, and more preferably 8 cm ³ /10 min or more and 20 cm ³ /10 min or less. This improves the moldability of the three-dimensionally molded insulator 1 during secondary processing, particularly the ability to prevent defects such as distortion during vacuum molding. If the melt volume rate is below the lower limit, the fluidity may be insufficient and moldability may be reduced. On the other hand, if the melt volume rate is above the upper limit, the impact resistance of the molded body may be reduced. The melt volume rate is measured in accordance with the test method specified in JIS K 7210:2014.

3.2.1 Polyolefin Resin Examples of polyolefin resins include high-density polyethylene resin, polypropylene resin, polybutene resin, ethylene-(meth)acrylic acid copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-vinyl acetate copolymer, maleic anhydride-modified polyethylene, carboxylic acid-modified polyethylene, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer.

Polyolefin resins have excellent chemical resistance to a variety of chemicals. Furthermore, polyolefin resins have good tracking resistance due to their hydrocarbon chain structure. Therefore, polyolefin resins contribute to improving the chemical resistance and tracking resistance of the three-dimensional molded insulator 1.

Among these, polypropylene resin is preferably used. Polypropylene resin particularly improves the chemical resistance and tracking resistance of the three-dimensional molded insulator 1.

3.2.2. Polyamide Resin Examples of polyamide resins include polycaproamide (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecamethylene adipamide (polyamide 116), polyundecaneamide (polyamide 11), polydodecanamide (polyamide 12), polytrimethylhexamethylene terephthalamide (polyamide TMHT), polyhexamethylene terephthalamide (polyamide 6T), polyhexamethylene isophthalamide (polyamide 6I), and polyhexamethylene sebacamide (polyamide 610). Examples of the polyisopropylamine include ethylene terephthalic/isophthalamide (polyamide 6T/6I), polybis(4-aminocyclohexyl)methanedodecamide (polyamide PACM12), polybis(3-methyl-4-aminocyclohexyl)methanedodecamide (polyamide dimethyl PACM12), polymetaxylylene adipamide (polyamide MXD6), polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), polyundecamethylene terephthalamide (polyamide 11T), and polyundecamethylene hexahydroterephthalamide (polyamide 11T(H)), and copolymers or mixtures thereof may also be used.

Polyamide resin can be obtained by polymerizing or copolymerizing nylon salts, which are made from diamines and dicarboxylic acids, using known methods such as melt polymerization, solution polymerization, and solid-state polymerization. Using polyamide resins as the first and second resins can further improve the tracking resistance of the three-dimensionally molded insulator 1.

The diamine may be an aliphatic diamine, but alicyclic diamines or aromatic diamines are preferably used, with alicyclic diamines being more preferred. By using these, it is possible to prepare polyamide resins having a cyclic structure such as an aromatic ring structure or an alicyclic structure. Such polyamide resins contribute to improving the heat resistance of the three-dimensionally molded insulator 1. Furthermore, alicyclic diamines in particular contribute to improving the tracking resistance of the three-dimensionally molded insulator 1.

Examples of alicyclic diamines include 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 1,3-cyclohexanedimethylamine, 1,4-cyclohexanedimethylamine, bis(4-aminocyclohexyl)methane, bis(4-aminocyclohexyl)propane, bis(3-methyl-4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)propane, 5-amino-2,2,4-trimethyl-1-cyclopentanemethylamine, 5-amino-1,3,3-trimethylcyclohexanemethylamine (isophoronediamine), bis(aminopropyl)piperazine, bis(aminoethyl)piperazine, norbornanedimethylamine, and tricyclodecanedimethylamine, and one or more of these may be used.

Examples of aromatic diamines include m-xylylenediamine and p-xylylenediamine.

The dicarboxylic acid may be an alicyclic dicarboxylic acid or an aromatic dicarboxylic acid, but an aliphatic dicarboxylic acid is preferably used. This allows the preparation of a polyamide resin with a hydrocarbon chain structure. Such a polyamide resin contributes to improving the tracking resistance of the three-dimensionally molded insulator 1.

Dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosanedioic acid; alicyclic dicarboxylic acids such as 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, dicyclohexanemethane-4,4'-dicarboxylic acid, and norbornanedicarboxylic acid; and aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. One or more of these may be used.

The polyamide resin preferably used is polyamide 6T, polyamide PACM12, polyamide dimethyl PACM12, polyamide MXD6, polyamide 9T, polyamide 10T, polyamide 11T, or polyamide 11T(H), and more preferably polyamide PACM12 or polyamide dimethyl PACM12. These have both a cyclic structure such as an aromatic ring structure or an alicyclic structure, and a structure derived from an aliphatic monomer, and therefore contribute to improving both the heat resistance and tracking resistance of the three-dimensionally molded insulator 1.
Polyamide PACM12 contains a structural unit represented by the following formula (2).

The polyamide PACM12 is synthesized from bis(4-aminocyclohexyl)methane (PACM) and dodecanedioic acid.
Polyamide dimethyl PACM12 contains a structural unit represented by the following formula (3).

The above-mentioned polyamide dimethyl PACM12 is synthesized using bis(3-methyl-4-aminocyclohexyl)methane (MACM) and dodecanedioic acid as raw materials.

3.2.3 Aliphatic Polycarbonate Resins Examples of aliphatic polycarbonate resins include resins containing aliphatic carbonate units having 2 to 12 carbon atoms. Specific examples include polyethylene carbonate, polypropylene carbonate, polytrimethylene carbonate, polytetramethylene carbonate, polypentamethylene carbonate, polyhexamethylene carbonate, polyheptamethylene carbonate, polyoctamethylene carbonate, polynonamemethylene carbonate, polydecamethylene carbonate, polyoxydiethylene carbonate, poly-3,6-dioxyoctane carbonate, poly-3,6,9-trioxyundecane carbonate, polyoxydipropylene carbonate, polycyclopentene carbonate, and polycyclohexene carbonate.

The aliphatic polycarbonate resin may also be a resin containing aliphatic carbonate units containing a diol residue represented by the following formula (4):

(In formula (4), R ⁵ to R ⁸ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group.)

Aliphatic polycarbonate resins preferably contain 30 mol% to 100 mol% of aliphatic carbonate units containing a diol residue represented by formula (4) above, and more preferably 50 mol% to 90 mol% of all structural units.

The diol residue represented by the above formula (4) has a structure in which two tetrahydrofuran rings are fused together. By including such a structure in the structural unit, the glass transition temperature Tg of the aliphatic polycarbonate resin can be increased. As a result, a three-dimensional molded insulator 1 with excellent heat resistance and tracking resistance can be obtained.

Examples of diols that constitute the diol residue represented by formula (4) above include isosorbide, isomannide, and isoidide. These carbohydrate-derived diols are useful in that they can also be obtained from natural biomass.

3.2.4 Aromatic Polycarbonate Resin Aromatic polycarbonate resins can be obtained by methods such as the phosgene process in which various dihydroxydiaryl compounds are reacted with phosgene, the transesterification process in which a dihydroxydiaryl compound is reacted with a carbonate ester such as diphenyl carbonate, the ring-opening polymerization of a cyclic carbonate compound, or the interfacial polycondensation process. Such aromatic polycarbonate resins impart excellent heat resistance and flame retardancy to the three-dimensionally molded insulator 1 due to their aromatic ring structure.

In addition to bisphenol A, dihydroxydiaryl compounds include bis(hydroxyaryl)alkanes such as bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis(4-hydroxyphenyl-3-methylphenyl)propane, and 1,1-bis(4-hydroxy-3-tert-butylphenyl)propane, and bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclopentane and 1,1-bis(4-hydroxyphenyl)cyclohexane. Examples include ketones, dihydroxydiaryl ethers such as 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide, dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide, and dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone. These may be used alone or in combination of two or more.

Aromatic polycarbonate resins include, in particular, resins having structural units represented by the following formula (1):

(In formula (1), ^R1 and ^R2 independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a halogen atom. m and n independently represent an integer of 0 to 4. X represents a direct bond, O, S, SO, _SO2 , ^CR3R4 ( ^{R3 and R4} independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and may be the same or different), an alkylene group having 2 to 10 carbon atoms, a polydimethylsiloxane group, or C( _CF3 ) ₂ .)

Aromatic polycarbonate resins having structural units represented by the above formula (1) impart particularly excellent heat resistance and flame retardancy to the three-dimensionally molded insulator 1.

Among all the structural units constituting the aromatic polycarbonate resin, the proportion of structural units represented by the above formula (1) is preferably 55 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more.

From the viewpoints of availability, cost, etc., it is preferable that R ¹ and R ² are each a hydrogen atom, X is CR ³ R ⁴ , and R ³ and R ⁴ are each a methyl group or a hydrogen atom.

The aromatic polycarbonate resin is preferably a polycarbonate resin having structural units derived from bisphenol A (2,2-bis(4-hydroxyphenyl)propane). This further enhances the flame retardancy and heat resistance of the three-dimensional molded insulator 1.

The viscosity average molecular weight (M) of the aromatic polycarbonate resin is not particularly limited, but is preferably 5,000 or more and 100,000 or less, more preferably 12,000 or more and 35,000 or less, even more preferably 15,000 or more and 30,000 or less, and particularly preferably 18,000 or more and 28,000 or less.

The viscosity average molecular weight (M) is calculated from the viscosity (η) of a methylene chloride solution of the resin using the formula η = kM ^α , where k and α are constants specific to the polymer. The viscosity is measured using an Ubbelohde viscometer at 20°C.

Furthermore, the aromatic polycarbonate resin may be a blend of a resin with a high viscosity average molecular weight (high viscosity resin) and a resin with a low viscosity average molecular weight (low viscosity resin). This allows for the production of a three-dimensional molded insulator 1 with excellent moldability without compromising the heat resistance and flame retardancy inherent to the aromatic polycarbonate resin.

The difference between the viscosity average molecular weight of the high-viscosity resin and the viscosity average molecular weight of the low-viscosity resin is not particularly limited, but is preferably between 3,000 and 20,000, and more preferably between 5,000 and 10,000. This results in a three-dimensional molded insulator 1 with particularly good moldability.

When the blending amount of high-viscosity resin is M1 and the blending amount of low-viscosity resin is M2, the blending ratio M1/M2 is preferably 0.5 or more and 8.0 or less by mass, more preferably 0.8 or more and 6.0 or less, and even more preferably 0.9 or more and 5.0 or less. This results in a three-dimensional molded insulator 1 with particularly good moldability.

The glass transition temperature Tg of the aromatic polycarbonate resin is preferably 130°C or higher and lower than 160°C, and more preferably 140°C or higher and 155°C or lower. If the glass transition temperature Tg of the aromatic polycarbonate resin is within this range, the heat resistance and flame retardancy of the three-dimensional molded insulator 1 can be sufficiently improved. The glass transition temperature Tg of the aromatic polycarbonate resin is measured by DSC (differential scanning calorimetry). The heating rate in the DSC method is 10°C/min.

The content of aromatic polycarbonate resin in the three-dimensional molded insulator 1 is not particularly limited, but is preferably 70% by mass or more, and more preferably 80% by mass or more.

The melt volume rate (MVR) of the aromatic polycarbonate resin at 300°C and a load of 1.2 kg is preferably 5 cm ³ /10 min or more and 20 cm ³ /10 min or less, and more preferably 8 cm ³ /10 min or more and 15 cm ³ /10 min or less. This improves the moldability of the three-dimensionally molded insulator 1 during secondary processing, particularly the ability to prevent defects such as distortion during vacuum molding. If the melt volume rate is below the lower limit, the fluidity may be insufficient and moldability may be reduced. On the other hand, if the melt volume rate is above the upper limit, the impact resistance of the molded body may be reduced. The melt volume rate is measured in accordance with the test method specified in JIS K 7210:2014.

The aromatic polycarbonate resin may be a resin containing carbonate units (bisphenolisophorone carbonate units) represented by the following formula (5). Such aromatic polycarbonate resins have higher heat resistance than aromatic polycarbonate resins containing carbonate units represented by the above formula (1). Hereinafter, polycarbonate resins containing bisphenolisophorone carbonate units may be referred to as "heat-resistant polycarbonate resins."

In formula (5), R ^a and R ^b each independently represent an alkyl group having 1 to 12 carbon atoms, R ^g each independently represent an alkyl group having 1 to 12 carbon atoms, p and q each independently represent an integer of 0 to 4, and t represents an integer of 0 to 10.

It is preferred that at least one of R ^a and R ^b is located meta to the cyclohexylidene bridging group.

Furthermore, R ^a and R ^b are each independently an alkyl group having 1 to 4 carbon atoms, R ^g is an alkyl group having 1 to 4 carbon atoms, p and q are each 0 or 1, and t may be 0 to 5.

Furthermore, R ^a , R ^b , and R ^g are each a methyl group, p and q are each 0 or 1, and t is 0 or 3, preferably 0.

A specific example of such a heat-resistant polycarbonate resin is a resin containing carbonate units (bisphenol A carbonate units) derived from bisphenol A (2,2-bis(4-hydroxyphenyl)propane) and carbonate units (bisphenol isophorone carbonate units) represented by formula (5). In this case, it is preferable that p and q in the bisphenol isophorone carbonate units are each 0, each R ^g is a methyl group, and t is 3. In this case, the bisphenol isophorone carbonate units are particularly carbonate units containing a structure derived from bisphenol TMC (1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane).

Such bisphenol isophorone carbonate units contain both aromatic ring structures and alicyclic structures. Therefore, the bisphenol isophorone carbonate units contribute particularly to improving both the heat resistance (flame retardancy) and tracking resistance of the three-dimensional molded insulator 1.

Among all the structural units constituting the heat-resistant polycarbonate resin, the proportion of bisphenol isophorone carbonate units is preferably 30% by mass or more, more preferably 35% to 60% by mass, and even more preferably 40% to 50% by mass. This contributes to improving both the heat resistance (flame retardancy) and tracking resistance of the three-dimensional molded insulator 1. It also improves the moldability of the heat-resistant polycarbonate resin.

If the proportion of bisphenol isophorone carbonate units falls below the lower limit, at least one of the heat resistance (flame retardancy) and tracking resistance of the three-dimensionally molded insulator 1 may decrease. On the other hand, if the proportion of bisphenol isophorone carbonate units exceeds the upper limit, the moldability of the heat-resistant polycarbonate resin may decrease, and the dimensional accuracy of the three-dimensionally molded insulator 1 may decrease.

The glass transition temperature Tg of the heat-resistant polycarbonate resin is preferably 160°C or higher and 230°C or lower, and more preferably 165°C or higher and 220°C or lower. If the glass transition temperature Tg of the heat-resistant polycarbonate resin is within this range, the heat resistance of the three-dimensional molded insulator 1 can be particularly improved. As a result, even if creeping discharge occurs in the three-dimensional molded insulator 1, discoloration due to carbonization can be particularly suppressed, thereby particularly suppressing the occurrence of poor appearance and the deterioration of insulation properties due to carbonization.

If the glass transition temperature Tg is below the lower limit, there is a risk that poor appearance and carbonization due to creeping discharge may occur. On the other hand, if the glass transition temperature Tg is above the upper limit, the molding temperature of the heat-resistant polycarbonate resin may become too high, making molding defects more likely to occur. Furthermore, when heat-resistant polycarbonate resin is alloyed with a compatible resin, there is a risk that thermal degradation of the compatible resin may occur, depending on the heat resistance of the compatible resin.

3.2.5. Polymer Alloy The constituent material of the three-dimensionally molded insulator 1 may include a polymer alloy formed by alloying an aromatic polycarbonate resin with a compatible resin. A polymer alloy refers to a single-phase material or a stable multi-phase material formed by mixing multiple polymers, preferably a single-phase material. As used herein, "alloying" refers to the preparation of such a single-phase or multi-phase material by kneading or otherwise mixing raw materials containing multiple polymers. In particular, alloying an aromatic polycarbonate resin with a compatible resin provides a three-dimensionally molded insulator 1 that combines the heat resistance inherent in the aromatic polycarbonate resin with other properties inherent in the compatible resin.

Preferably, the compatible resins used are the aforementioned polyolefin resins, polyamide resins, aliphatic polycarbonate resins, and aromatic polycarbonate resins (heat-resistant polycarbonate resins) containing carbonate units represented by formula (5) above. In this case, the aromatic polycarbonate resin alloyed with these compatible resins is preferably a resin having a structural unit represented by formula (1) above. In such a combination, the tracking resistance (comparative tracking index CTI) of the compatible resin is higher than that of the aromatic polycarbonate resin having a structural unit represented by formula (1) above. This results in a three-dimensional molded insulator 1 that combines heat resistance and tracking resistance.

The proportion of the compatible resin in the polymer alloy is not particularly limited, but is preferably 5% by mass or more and 80% by mass or less, more preferably 10% by mass or more and 75% by mass or less, even more preferably 20% by mass or more and 70% by mass or less, and particularly preferably 40% by mass or more and 65% by mass or less. This configuration makes it possible to achieve a polymer alloy that has a good balance between the properties of the compatible resin, such as heat resistance and flame retardancy, of the aromatic polycarbonate resin having the structural unit represented by formula (1) above.

The comparative tracking index CTI of the compatible resin is preferably 400 V or higher, and more preferably 600 V or higher. This results in a three-dimensional molded insulator 1 with particularly good tracking resistance.

Furthermore, the comparative tracking index CTI of the compatible resin is preferably at least 50 V higher than the comparative tracking index CTI of the aromatic polycarbonate resin, and more preferably at least 100 V higher. This results in a three-dimensional molded insulator 1 that better combines flame retardancy and tracking resistance.

The glass transition temperature Tg of the compatible resin is preferably 125°C or higher, and more preferably 130°C or higher and 230°C or lower. This gives the compatible resin heat resistance, making it easier to suppress discoloration due to carbonization, even if creeping discharge occurs in the three-dimensional molded insulator 1. As a result, it is possible to suppress the occurrence of poor appearance in the three-dimensional molded insulator 1 and the deterioration of insulation properties due to carbonization.

Furthermore, the compatible resin preferably has an aromatic monomer molar fraction of 90% or less, more preferably 70% or less, and even more preferably 50% or less of the total monomer components. Such a compatible resin has a relatively high proportion of structures derived from aliphatic monomers. This allows the three-dimensionally molded insulator 1 to have good tracking resistance. This results in a three-dimensionally molded insulator 1 that is better in both flame retardancy and tracking resistance. Furthermore, even if creeping discharge occurs in the three-dimensionally molded insulator 1, discoloration due to carbonization can be more easily suppressed. As a result, the occurrence of poor appearance in the three-dimensionally molded insulator 1 and a decrease in insulating properties due to carbonization can be suppressed. Note that aromatic monomer refers to a monomer (aromatic compound) that contains an aromatic ring structure.

The polymer alloy may also contain resins other than the above components. In other words, the polymer alloy may be an alloy of three or more resins.

An example of a method for preparing a polymer alloy is described below. First, the raw materials are premixed, then melted and kneaded using a batch kneader or twin-screw extruder. This mechanically stirs the raw materials, resulting in a kneaded product containing a polymer alloy. The kneading and melting conditions are set appropriately depending on the type and blending ratio of the raw materials, but examples include a temperature of 200-250°C, a screw rotation speed of 300-1000 rpm, and a kneading time of approximately 3-20 minutes. Next, the kneaded product is pelletized as necessary.

Furthermore, a compatibilizer may be added to the raw materials as needed. By adding a compatibilizer, the compatibility of the resins being alloyed can be further improved.

The amount of compatibilizer added is preferably 2 to 30 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of resin.

3.2.6 Additives The three-dimensionally molded insulator 1 may contain any additive. Examples of additives include flame retardants, colorants, stabilizers, lubricants, processing aids, antistatic agents, antioxidants, neutralizing agents, UV absorbers, dispersants, thickeners, mold release agents, fillers, flow improvers, plasticizers, and antibacterial agents. Note that one type of additive may be contained, or two or more types may be contained in any combination.

Of these, the flame retardant enhances the flame retardancy of the three-dimensionally molded insulator 1 .
Examples of the flame retardant include inorganic phosphorus-based flame retardants such as halogen-based flame retardants, red phosphorus and polyphosphate-based flame retardants such as ammonium polyphosphate, organic phosphorus-based flame retardants such as triaryl phosphate ester compounds, metal hydroxide-based compounds, antimony oxide-based compounds, nitrogen-containing compounds, etc. Furthermore, the flame retardant may be a combination of two or more of these.

Among these, phosphorus-based flame retardants or nitrogen-containing compounds are preferably used as flame retardants, with nitrogen-containing compounds being more preferred. When the flame retardant contains a nitrogen-containing compound, the flame retardancy of the three-dimensional molded insulator 1 can be further improved. Furthermore, because nitrogen-containing compounds do not contain halogen atoms, a so-called halogen-free, fluorine-free three-dimensional molded insulator 1 can be realized.

Examples of the nitrogen-containing compound include compounds having a triazine skeleton.
Examples of compounds having a triazine skeleton include melamine; melamine derivatives such as butyl melamine, trimethylol melamine, hexamethylol melamine, hexamethoxymethyl melamine, and melamine phosphate; cyanuric acid; cyanuric acid derivatives such as methyl cyanurate, diethyl cyanurate, trimethyl cyanurate, and triethyl cyanurate; isocyanuric acid; isocyanuric acid derivatives such as methyl isocyanurate, N,N'-diethyl isocyanurate, trismethyl isocyanurate, trisethyl isocyanurate, bis(2-carboxyethyl)isocyanurate, 1,3,5-tris(2-carboxyethyl)isocyanurate, and tris(2,3-epoxypropyl)isocyanurate; melamine cyanurate; and melamine isocyanurate. These compounds can be used alone or in combination of two or more.

Among these, the compound having a triazine skeleton is preferably one or more melamine-based compounds selected from the group consisting of melamine, melamine cyanurate, melamine isocyanurate, and derivatives thereof, with melamine cyanurate being more preferred. This can particularly enhance the flame retardancy of the three-dimensional molded insulator 1.

The amount of flame retardant added is preferably 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of resin. By keeping the amount of flame retardant added within this range, the effect of enhancing flame retardancy is fully realized, while side effects such as reduced mechanical properties due to excess flame retardant can be suppressed.

The flame retardant is, for example, in particulate form. In this case, the average particle size of the flame retardant is preferably 0.01 μm or more and 10 μm or less, more preferably 0.05 μm or more and 5 μm or less, and even more preferably 0.2 μm or more and 2 μm or less. When the average particle size of the flame retardant is within the above range, the dispersibility of the flame retardant is particularly good, thereby particularly enhancing the flame retardancy of the three-dimensional molded insulator 1. The average particle size of the flame retardant is the particle size at which the cumulative total from the small diameter side in the volume-based particle size distribution is 50% as measured using a laser diffraction particle size distribution analyzer.

Furthermore, the total amount of additives added is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, and even more preferably 0.5 to 3 parts by mass, per 100 parts by mass of resin.

3.3 Multilayer Structure Next, a three-dimensionally shaped insulator 1 according to a modified example will be described.
FIG. 7 is a cross-sectional view showing a three-dimensionally shaped insulator 1 according to a modified example.

The following describes a modified three-dimensionally molded insulator 1. However, the following explanation focuses on the differences from the three-dimensionally molded insulator 1 shown in Figure 1, and similar points will not be explained again.

The three-dimensionally molded insulator 1 shown in Figure 7 is similar to the three-dimensionally molded insulator 1 shown in Figure 1, except that it has a multi-layer structure.

The three-dimensional molded insulator 1 shown in Figure 7 has a first layer 101, an intermediate layer 103, and a second layer 102, which are layered from bottom to top. The intermediate layer 103 has a lower surface (first surface) and an upper surface (second surface) that are opposite each other, and preferably contains an aromatic polycarbonate resin and a flame retardant. The first layer 101 is layered on the lower surface (first surface) of the intermediate layer 103 and contains a first resin. The second layer 102 is layered on the upper surface (second surface) of the intermediate layer 103 and contains a second resin. The first resin and the second resin are preferably materials with higher tracking resistance than the aromatic polycarbonate resin contained in the intermediate layer 103.

With this configuration, the aromatic polycarbonate resin is a polycarbonate resin containing an aromatic ring structure in the main chain, and the high proportion of aromatic ring structures provides the intermediate layer 103 with good heat resistance. The intermediate layer 103 also contains a flame retardant. These factors act to provide the intermediate layer 103 with good flame retardancy.

Furthermore, the intermediate layer 103 is sandwiched between the first layer 101 and the second layer 102. Therefore, if a creeping discharge occurs in the three-dimensionally molded insulator 1, the intermediate layer 103 is prevented from being directly exposed to arc discharge, etc. By using a material with higher tracking resistance than aromatic polycarbonate resin as the resin contained in the first layer 101 and the second layer 102, the three-dimensionally molded insulator 1 is endowed with good tracking resistance. Therefore, a three-dimensionally molded insulator 1 with excellent flame retardancy and tracking resistance is obtained.

Furthermore, with this configuration, one of the effects of the multi-layer structure is improved pinhole resistance. Improved pinhole resistance further enhances the insulation properties, flame retardancy, and tracking resistance of the three-dimensional molded insulator 1.

The comparative tracking index CTI of each of the first resin and second resin is preferably 400 V or higher, and more preferably 600 V or higher. This results in a first resin and second resin with particularly good tracking resistance.

Furthermore, the comparative tracking index CTI of each of the first resin and the second resin is preferably at least 50 V higher than the comparative tracking index CTI of the aromatic polycarbonate resin, and more preferably at least 100 V higher. This results in a three-dimensional molded insulator 1 that better balances flame retardancy and tracking resistance.

The glass transition temperature Tg of each of the first resin and the second resin is preferably 125°C or higher, and more preferably 130°C or higher and lower than 200°C. This provides heat resistance to the first resin and the second resin, making it easier to suppress coloration due to carbonization even if creeping discharge occurs in the first layer 101 and the second layer 102, for example. As a result, the occurrence of poor appearance in the first layer 101 and the second layer 102 and the deterioration of insulation due to carbonization can be suppressed. The glass transition temperature Tg of each of the first resin and the second resin is measured using a differential scanning calorimeter (DSC) method. The heating rate in the DSC method is 10°C/min.

The melt volume rate (MVR) of each of the first resin and the second resin at 300°C and a load of 1.2 kg is preferably 5 cm ³ /10 min or more and 30 cm ³ /10 min or less, and more preferably 8 cm ³ /10 min or more and 20 cm ³ /10 min or less. This improves the moldability of the three-dimensionally molded insulator 1 during secondary processing, particularly the ability to prevent defects such as distortion during vacuum molding. If the melt volume rate is below the lower limit, the fluidity may be insufficient and moldability may be reduced. On the other hand, if the melt volume rate is above the upper limit, the impact resistance of the molded body may be reduced. The melt volume rate is measured in accordance with the test method specified in JIS K 7210:2014.

Furthermore, the first resin and second resin preferably have an aromatic monomer molar fraction of 90% or less, more preferably 70% or less, and even more preferably 50% or less, of the total monomer components. Such first resins and second resins have a relatively high proportion of structures derived from aliphatic monomers. This provides the first resin and second resin with good tracking resistance. This results in first resins and second resins with better flame retardancy and tracking resistance. Furthermore, even if creeping discharge occurs in the three-dimensionally molded insulator 1, discoloration due to carbonization can be more easily suppressed. As a result, the occurrence of poor appearance in the three-dimensionally molded insulator 1 and the deterioration of insulating properties due to carbonization can be suppressed. Note that aromatic monomer refers to a monomer (aromatic compound) containing an aromatic ring structure.

The content of the first resin in the first layer 101 and the content of the second resin in the second layer 102 are preferably 70% by mass or more, and more preferably 80% by mass or more.
The first resin and the second resin may be the resin materials described above.

Here, the tracking resistance and glass transition temperature Tg of resins (compounds) that can be used for the three-dimensionally molded insulator 1 according to this embodiment are exemplified. Table 1 below lists the CTI value, which indicates tracking resistance, and the glass transition temperature Tg for various resins that can be used as the resin materials (including the first resin and second resin) mentioned above, and for the aromatic polycarbonate resin mentioned above. For aromatic polycarbonate resins, the viscosity average molecular weight is also listed.

As shown in Table 1, aromatic polycarbonate resins tend to have slightly lower tracking resistance than other resins. For this reason, using these resins in combination with aromatic polycarbonate resins is useful from the perspective of achieving the best possible properties of both resins.

Methods for manufacturing the three-dimensional molded insulator 1 shown in Figure 7 include, for example, co-extrusion, dry lamination, extrusion lamination, and hot melt.

3.4. Characteristics of the Three-Dimensional Molded Insulator Next, the characteristics of the three-dimensionally molded insulator 1 according to the embodiment will be described.

3.4.1. Tracking Resistance The tracking resistance of the three-dimensionally shaped insulator 1 according to the embodiment can be quantified by the comparative tracking index CTI, which is an index of tracking resistance measured in accordance with ASTM D3638.

The comparative tracking index CTI (CTI value) of the three-dimensionally molded insulator 1 according to the embodiment is preferably 600 V or higher. If the CTI value is within the above range, the rank PLC, which indicates tracking resistance, will be the highest rank of 0. Therefore, it can be said that a three-dimensionally molded insulator 1 with a CTI value within the above range has particularly good tracking resistance.

The measurement method specified in IEC 60112, 3rd Edition, measures the CTI value using a 0.1% by mass aqueous solution of ammonium chloride and a platinum electrode. More specifically, the specified number of drops (50 drops) of this ammonium chloride aqueous solution are added, and the voltage at which none of the test pieces (n=5) breaks down is determined, and this is taken as the CTI value.

The test specimen used is a three-dimensionally molded insulator 1 with a thickness of 3 mm or more. The test specimen may also be constructed by stacking multiple three-dimensionally molded insulators 1.

The methods for measuring the comparative tracking index CTI of the first resin and second resin, and the comparative tracking index CTI of the aromatic polycarbonate resin, are also the same as those described above. In this case, the test specimens used are sheets of these resins obtained by extrusion molding, each having a thickness of 3 mm or more.

3.4.2. Flame Retardancy The flame retardancy of the three-dimensionally molded insulator 1 according to the embodiment can be quantified by the flame retardancy rank determined in accordance with the UL94 standard (rank determined by the UL94V test or UL94VTM test).

The flame retardancy of the three-dimensional molded insulator 1 according to the embodiment is preferably such that the UL94V test results in a V-0 rating for test specimens with a thickness of 0.4 mm or more, or the UL94VTM test results in a VTM-0 rating for test specimens with a thickness of 0.4 mm or more.

Three-dimensional molded insulators 1 that meet these evaluation ranks achieve the highest rank in each test, and therefore can be said to have particularly good flame retardancy.

In the UL94V test, a vertical combustion test is conducted using test specimens measuring 125±5mm x 13.0±0.5mm and with a thickness of 0.4mm or more and less than 13mm.

The UL94VTM test is also performed when the test specimen is too thin to perform the UL94V test. The UL94VTM test involves a vertical flame test using a test specimen measuring 200mm x 50mm and with a thickness of 0.4mm to 0.25mm.

3.4.3. Breakdown Voltage The breakdown voltage of the three-dimensionally shaped insulator 1 according to the embodiment is a breakdown voltage measured in accordance with the method for measuring breakdown strength (AC test) specified in JIS C 2318:2020.

The breakdown voltage of the three-dimensionally molded insulator 1 according to the embodiment is preferably 5 kV or higher, more preferably 7 kV to 60 kV, and even more preferably 10 kV to 50 kV. A three-dimensionally molded insulator 1 that satisfies this breakdown voltage contributes to ensuring sufficient insulation even when the insulation clearance is short. Note that the breakdown voltage may exceed the upper limit, but is preferably below the upper limit when considering minimizing individual differences.

4. Manufacturing Method of Three-Dimensional Molded Insulator Next, a method of manufacturing the three-dimensionally molded insulator 1 (a method of manufacturing a three-dimensionally molded insulator according to the embodiment) will be described.

First, a flat thermoplastic insulating sheet is produced using raw materials containing the above-mentioned resin material by methods such as calendaring, extrusion, pressing, or casting. Thermoplastic insulating sheets with a multilayer structure are produced using the methods described above.

Next, the thermoplastic insulating sheet is subjected to secondary processing, including thermoforming, to form the recesses 12. Thermoforming methods include vacuum forming, pressure forming, and vacuum pressure forming. This type of thermoforming results in a three-dimensionally formed insulator 1 with little variation in thickness due to shape and high shape precision. Furthermore, vacuum forming and vacuum pressure forming can achieve particularly high shape precision.

The heating temperature during thermoforming is not particularly limited, but is preferably between 130°C and 260°C, and more preferably between 140°C and 240°C. This results in a three-dimensionally molded insulator 1 with particularly little variation in thickness and particularly high shape precision.

Furthermore, other secondary processes may be added before or after thermoforming. Examples of other secondary processes include folding, punching, etc.

5. Method of Using the Three-Dimensional Molded Insulator Next, an example of using the three-dimensionally molded insulator 1 will be described.

Figure 8 is a cross-sectional view showing a control device 8 in which a three-dimensional molded insulator 1 and a circuit board 9 according to the embodiment are housed within a case 80.

The control device 8 shown in Figure 8 comprises a circuit board 9, a three-dimensional molded insulator 1, and a case 80 that houses these. Note that the device that comprises the circuit board 9 is not limited to the control device 8, and may be a device with any function.

The case 80 is box-shaped with a bottom and includes a housing 81 that is open at the top, a lid 82 that covers the opening of the housing 81, and a heat dissipation sheet 85.

The housing 81 has a bottom that extends along the X-Y plane and a wall that rises upward from the outer edge of the bottom. A circuit board 9 is housed inside the housing 81. The circuit board 9 is fixed to the housing 81 with fixing screws 94 (not shown in Figure 8). The circuit board 9 is also fixed in contact with the heat dissipation sheet 85.

The lid 82 only needs to cover the opening of the housing 81, but it is preferable that it be liquid-tight or airtight. This ensures stable protection of the circuit board 9 from the external environment.

The materials that make up the housing 81 and the lid 82 include, for example, metal materials, ceramic materials, and resin materials. They may also be composite materials made up of two or more of these. Of these, metal materials are preferred. Metal materials have excellent thermal conductivity and mechanical properties, making them useful as materials for making up the housing 81 and the lid 82. Furthermore, metal materials often have excellent electrical conductivity and magnetic permeability, making it possible to use the housing 81 and the lid 82 as electromagnetic shields or magnetic field shields.

Furthermore, when a metal material is used, there is a concern that a short circuit may occur between the circuit board 9 and the metal material. Short circuits are particularly likely to occur between the components protruding from the top surface of the wiring board 90 and the lid portion 82, so conventionally, it would be necessary to ensure a necessary spatial distance between these two.

In contrast, by using the three-dimensional molded insulator 1, this spatial distance can be shortened. For example, as shown in Figure 8, the distance S3 between the power semiconductor element 91 and the lid portion 82, and the distance S4 between the bus bar 92 and the lid portion 82 can both be shortened. This makes it possible to make the control device 8 thinner and more compact.

The separation distances S3 and S4 vary depending on factors such as the voltage applied to the components, but as an example, they are preferably 10 mm or less, and more preferably 5 mm or less. This allows the control device 8 to be made even thinner and more compact.

Furthermore, by using the three-dimensional molded insulator 1, sufficient space SP can be secured between the flat portion 11 of the three-dimensional molded insulator 1 and the lid portion 82. This space SP ensures insulation from the power semiconductor element 91 and bus bar 92, so even if it is used to house another object, for example, the occurrence of short circuits can be suppressed.

FIG. 9 is a cross-sectional view showing a modification of the control device 8 of FIG.
The case 80 shown in FIG. 9 is similar to the case 80 shown in FIG. 8 except that a partition wall 83 is added. The partition wall 83 is installed inside the housing 81 and separates the interior space of the housing 81 into upper and lower sections. A circuit board 9 and a three-dimensionally molded insulator 1 are accommodated in the space below the partition wall 83. A circuit board 7 separate from the circuit board 9 is accommodated in the space above the partition wall 83. The circuit board 7 includes a wiring board 71 and a semiconductor element 72. By accommodating such a circuit board 7 in the same space as the circuit board 9, the height of the case 80 can be minimized while enhancing the functionality of the control device 8.

In addition, another flat insulating sheet 2 is provided on the underside of the lid portion 82 shown in Figure 9. This flat insulating sheet 2 has a flat plate shape. By providing such a flat insulating sheet 2, the required spatial distance between the circuit board 7 and the lid portion 82 can be shortened. This allows the height of the case 80 to be further reduced.

As described above, by using the three-dimensional molded insulator 1 and the flat insulating sheet 2 together, it is possible to achieve both high functionality and compactness in the control device 8.

6. Advantages of the Present Embodiment The three-dimensionally shaped insulator 1 according to the present embodiment is a three-dimensionally shaped insulator that is placed over a component to which voltage is applied. Such a three-dimensionally shaped insulator 1 is molded into a shape having a recess 12. The recess 12 includes a bottom 12a and a wall 12b provided at an end of the bottom 12a. The three-dimensionally shaped insulator 1 is used with a component inserted into the recess 12.

With this configuration, by providing recesses 12 that align with the components to which voltage is applied, it is possible to reduce the dead space that occurs around the components. This allows for more efficient use of the space in which the components are housed. As a result, it is possible to miniaturize the equipment in which the components are mounted.

It may also be used by placing it over a circuit board 9 that includes components and a wiring board 90 (substrate) on which the components are mounted. In this case, the three-dimensionally molded insulator 1 is preferably molded into a shape that has a recess 12 and a flat portion 11 connected to the recess 12.

With this configuration, by providing recesses 12 that fit the components mounted on the wiring board 90, it is possible to reduce the dead space that occurs between the circuit board 9 and the three-dimensionally molded insulator 1 (around the components). This allows for more effective use of the space in which the circuit board 9 is housed. As a result, it is possible to reduce the size of the device in which the circuit board 9 is mounted.

Furthermore, the three-dimensionally molded insulator 1 according to the embodiment has a through hole 13 that penetrates the flat portion 11 in the thickness direction.

With this configuration, when a fixing screw 94 or the like is provided in line with the through hole 13, the fixing screw 94 can be rotated even when the three-dimensional molded insulator 1 is placed over the circuit board 9. This makes it possible to screw the circuit board 9 to a case or the like with the three-dimensional molded insulator 1 placed over the circuit board 9, improving assembly workability.

Furthermore, it is preferable that the thickness t12b of the wall portion 12b be 20% or more and 95% or less of the thickness t11 of the flat portion 11.

With this configuration, the wall portion 12b has sufficient rigidity to support the shape of the recess 12 and can contribute to further reducing the dead space on the sides of the recess 12.

Furthermore, it is preferable that the thickness t11 of the flat portion 11 be 0.05 mm or more and 1.00 mm or less.

This configuration results in a three-dimensional molded insulator 1 that is excellent in flame retardancy, tracking resistance, and insulation, and is relatively easy to manufacture.

The three-dimensionally molded insulator 1 according to the embodiment may also contain a flame retardant.
With this configuration, a three-dimensional molded insulator 1 having excellent flame retardancy can be obtained.

Furthermore, it is preferable that the three-dimensional molded insulator 1 according to the above embodiment is primarily made of thermoplastic resin.

Sheets made primarily of thermoplastic resin are capable of plastic deformation due to heat, making them suitable for secondary processing. This allows them to be manufactured by thermoforming, resulting in a three-dimensionally molded insulator 1 that is easy to manufacture.

The thermoplastic resin may also contain an aromatic polycarbonate resin.
With this configuration, the three-dimensional molded insulator 1 can be obtained, which has excellent heat resistance and flame retardancy due to the aromatic ring structure.

Furthermore, the three-dimensionally molded insulator 1 according to the above embodiment preferably has a comparative tracking index (CTI), which is an index of tracking resistance measured in accordance with ASTM D3638, of 600 V or more.

This configuration results in a three-dimensional molded insulator 1 with particularly good tracking resistance.

Furthermore, the three-dimensionally molded insulator 1 according to the embodiment preferably has a flame retardancy rank determined in accordance with the UL94 standard of V-0 or VTM-0 for test specimens with a thickness of 0.4 mm or more.
With this configuration, a three-dimensional molded insulator 1 having particularly good flame retardancy can be obtained.

Furthermore, the manufacturing method of the three-dimensional molded insulator according to the above embodiment is a manufacturing method of the three-dimensional molded insulator 1, in which a flat thermoplastic insulating sheet is subjected to secondary processing including thermoforming to form the recess 12.
With this configuration, it is possible to manufacture a three-dimensionally molded insulator with high shape accuracy.

The thermoforming is preferably vacuum forming or vacuum/pressure forming.
With this configuration, it is possible to manufacture a three-dimensionally molded insulator with particularly high shape accuracy.

The above describes the three-dimensionally molded insulator and the method for manufacturing the three-dimensionally molded insulator of the present invention, but the present invention is not limited to the above-described embodiment.

For example, the three-dimensionally molded insulator of the present invention may contain additives other than those described in the above embodiment.

Furthermore, the three-dimensionally molded insulator of the present invention may have layers with any desired function added to the layer structure described in the above embodiment, such as an adhesive layer, bonding layer, protective layer, or release layer.

Furthermore, the method for manufacturing a three-dimensionally molded insulator of the present invention may include any additional steps for any purpose added to the above embodiment.

The present invention provides a three-dimensionally molded insulator that can reduce the dead space that occurs around voltage-applied components and enable effective use of the space in which the voltage-applied components are housed. Furthermore, the present invention makes it possible to manufacture three-dimensionally molded insulators with high shape accuracy. Therefore, the present invention has industrial applicability.

1 Three-dimensionally molded insulator 2 Flat insulating sheet 7 Circuit board 8 Control device 9 Circuit board 11 Flat portion 12 Recess 13 Through hole 71 Wiring board 72 Semiconductor element 80 Case 81 Housing 82 Lid portion 83 Partition wall 85 Heat dissipation sheet 90 Wiring board 91 Power semiconductor element 92 Bus bar 93 Signal connector 94 Fixing screw 101 First layer 102 Second layer 103 Intermediate layer 110 Flat surface 121 Recess 122 Recess 123 Recess 901 Insulating layer 902 Wiring layer 903 Through wiring 904 Thermal via 921 Bus bar 922 Bus bar L1 Spatial distance S1 Separation distance S2 Separation distance S3 Separation distance S4 Separation distance SP Space

Claims (12)

A three-dimensionally shaped insulator that is placed over a component to which voltage is applied,
The container is molded into a shape having a recess including a bottom and a wall portion provided at an end of the bottom,
A three-dimensionally molded insulator characterized in that the component is inserted into the recess when used. The component is used by being placed over a circuit board including the component and a board on which the component is mounted,
The three-dimensionally molded insulator according to claim 1 , which is molded into a shape having the recess and a flat portion connected to the recess. The three-dimensionally molded insulator according to claim 2, having a through hole penetrating the flat portion in the thickness direction. The three-dimensionally molded insulator described in claim 3, wherein the thickness of the wall portion is 20% or more and 95% or less of the thickness of the flat portion. The three-dimensionally molded insulator according to claim 3 or 4, wherein the thickness of the flat portion is 0.05 mm or more and 1.00 mm or less. A three-dimensionally molded insulator according to any one of claims 1 to 4, which contains a flame retardant. A three-dimensional molded insulator according to any one of claims 1 to 4, whose main material is a thermoplastic resin. The three-dimensionally molded insulator according to claim 7, wherein the thermoplastic resin includes an aromatic polycarbonate resin. A three-dimensionally molded insulator according to any one of claims 1 to 4, having a comparative tracking index (CTI), an indicator of tracking resistance, measured in accordance with ASTM D3638, of 600 V or more. A three-dimensionally molded insulator according to any one of claims 1 to 4, whose flame retardancy measured in accordance with the UL94 standard is V-0 or VTM-0 for test specimens with a thickness of 0.4 mm or more. A method for manufacturing the three-dimensionally shaped insulator according to any one of claims 1 to 4, comprising the steps of:
A method for manufacturing a three-dimensional molded insulator, characterized in that a flat thermoplastic insulating sheet is subjected to secondary processing including thermoforming to form the recesses. The method for manufacturing a three-dimensionally formed insulator described in claim 11, wherein the thermoforming is vacuum forming or vacuum-pressure forming.