JP2005045111A - Component built-in flexible circuit board, laminated component built-in flexible circuit board and manufacturing method thereof - Google Patents

Abstract

Provided are a flexible circuit board with a built-in multilayer component that can make a highly reliable electrical connection at a shortest distance, a low resistance value, and can be easily laminated, and a method of manufacturing the same.
A wiring layer having an electrode portion made of a conductor, a sheet-like insulating substrate provided with a via hole or a through hole in a predetermined position of the wiring layer and a part of the wiring layer, wiring A capacitor 10 as one or more passive elements 8 electrically connected to the layer 2, a coil 11, a resistor 12, or a BGA type LSI 13 as an active element, and solder inside the via hole 5 or the through hole 4 7 is filled.
[Selection] Figure 4

Description

  The present invention relates to a composite integrated circuit board, and in particular, a passive element circuit is formed on a flexible sheet-like insulating substrate made of a resin or the like on which circuit wiring formed of a conductor such as a metal foil is placed, or a chip-like circuit board is formed. A component built-in flexible circuit board in which bare elements of active elements such as passive elements, ICs, and LSIs are arranged, and a multilayered structure in which multiple layers of component built-in flexible circuit boards are layered by connecting layers between through holes and via holes. The present invention relates to a multilayer component built-in flexible circuit board and a method of manufacturing the same.

  As demand for small and light products expands, electronic circuits for these products are required to have higher density mounting and to improve mass productivity. Increasing the density of electronic circuits has been promoted mainly by miniaturization, circuit board sheeting, and lamination. Conventionally, the substrate is laminated by forming a hole at a predetermined position of each substrate, plating the inner wall of the hole, and using a through hole or a via hole for connecting the target layers. Interlayer connection is performed. Usually, a hole that is opened so as to penetrate the entire substrate from top to bottom is a through hole, and a hole that connects only intermediate layers is called a via hole.

  A via hole for interlayer connection is formed in a thin-film multilayer wiring board with metal wiring, and via studs are formed by filling the via hole with the same type of conductive metal as the metal wiring by electroless plating. A technique for connecting layers has been proposed (see, for example, Patent Document 1). Further, the upper surface of the via hole is flattened by means such as polishing, a wiring layer is formed thereon, and a via hole for connecting to the next wiring layer can be formed immediately above the via hole, thereby reducing the connection distance. A technique for minimizing the length has been proposed (see, for example, Patent Document 2).

  For lamination, an insulating layer is provided on the first metal wiring layer formed on the upper surface of the substrate, a via hole is formed in the insulating layer by etching, and a conductive metal is filled in the via hole by electroless plating to form a via stud. After polishing the via stud upper surface as necessary, a second metal wiring layer is provided on the flat insulating layer and the via stud, and an insulating layer is further provided on the second metal wiring layer. There has also been proposed a technique for providing a multilayer wiring board suitable for a high-speed calculation function that can be provided and repeatedly connected in a short distance as much as possible, and is suitable for a high-speed calculation function (see, for example, Patent Document 2).

In addition, as a means for laminating a laminated substrate incorporating a passive element, second unit insulating substrates (referred to as prepreg substrates) are provided on both upper and lower sides of the first unit insulating substrate on which passive elements such as capacitors, resistors, and inductors are placed. And a third unit insulating substrate (substrate on which the wiring layer is placed) are arranged, and these unit insulating substrates are combined and formed integrally by hot pressing, and then a through hole is formed at a predetermined position. A technique for forming a substrate with a built-in passive element has been proposed in which a conductive layer is formed by electroless plating on the inner surface of the through-hole and is electrically connected (see, for example, Patent Document 3).
Japanese Patent Laid-Open No. 7-297551 (see pages 2 to 3 and FIG. 1) Japanese Patent Laid-Open No. 9-23065 (see pages 3 to 5 and FIG. 1) JP 2001-168534 A (refer to page 6, FIGS. 10, 11, and 12)

  The above-described conventional connection method and laminating method when laminating through holes and via holes have various problems as described below, and the solution thereof has been desired.

  The conventional method in which a conductive layer is formed on the inner surface of a through-hole or via-hole by means of plating to make an electrical connection is generally thin, so the conduction resistance value is large and the current capacity is small. There remains a problem in the reliability of circuit wiring. Furthermore, since a space remains open inside the through hole, components cannot be mounted on that portion, which is disadvantageous for reducing the area of the sheet substrate. In addition, if it is attempted to increase the plating thickness or completely fill the hole, there is a problem that it takes time for plating and the number of manufacturing steps increases. Also, the method of immersing in plating solution to increase the plating speed is difficult to bring this plating process after the process of forming passive elements such as capacitors, resistors, coils, etc., considering the influence on the passive elements. is there.

  On the other hand, in order to improve the conductivity, a method of filling a conductive resin can be considered, but in order to reliably fill the conductive resin into a small hole of the through hole, it is necessary to apply pressure and inject it. In addition to some problems in the reliability of the connection with metal, equipment for this process is necessary, which increases the manufacturing cost of the product. Also, due to the necessity of applying pressure, it is difficult to bring this process after the process of forming passive element parts such as capacitors, resistors, and coils in consideration of the influence on the passive elements.

  In addition, regarding another conventional lamination technique, the sequential lamination method in which the wiring layer and the insulating layer are sequentially formed on the upper surface of the substrate is in principle a method having a low degree of freedom in designing the structure of the substrate and the manufacturing process. In addition, there is a problem in terms of productivity in the manufacturing process. The method of integrally forming the unit insulating substrate on which the wiring layer and passive elements are mounted is excellent in productivity, but the electrical connection between each substrate is the electroless connection between the through hole and the conductive layer that are processed after the integral forming. Since all connections are made by plating, each wiring in each layer needs to be routed to the through-hole position, so that there is a problem that wiring design becomes difficult in addition to an increase in electrical resistance. .

  The present invention has been made in order to solve the above-described problems. Regarding the interlayer connection method and the lamination method using through holes and via holes, it is possible to laminate a plurality of passive components, thereby allowing freedom in device configuration and structural design. High degree of productivity, excellent productivity, low resistance layer connection can shorten wiring length, reduce transmission loss of high frequency signal, and can be applied to high speed signal processing equipment, making the product even thinner An object of the present invention is to provide a flexible circuit board with a built-in component, a flexible circuit board with a built-in multilayer component, and a manufacturing method thereof that can be miniaturized and highly functionalized.

  In order to solve the above problems, the component-embedded flexible circuit board according to the present invention includes a wiring layer having an electrode portion formed of a conductor, and a via hole or a through hole at a predetermined position of the wiring layer and a part of the wiring layer. It has a configuration in which a sheet-like insulating substrate and one or more passive elements or active elements that are electrically connected to and placed on the wiring layer are provided, and solder is filled in via holes or through holes. The component-embedded flexible circuit board according to the present invention has a configuration in which the passive element or active element is a chip-like element, a configuration in which the passive element or active element is a sheet-like element, and the passive element is directly molded on the surface of the sheet-like insulating substrate. The mounted configuration and the active element have a configuration in which a thin film semiconductor is directly molded and mounted on the sheet-like insulating substrate surface. Further, in the component built-in flexible circuit board of the present invention, the solder filled in all or part of the via hole or the through hole is formed so as to be higher than the upper surface of the wiring layer or the electrode part. A wiring layer having an electrode part is formed of a conductor on both upper and lower surfaces of the insulating substrate, a via hole or a through hole is provided in a predetermined position of the wiring layer and the electrode part, and the via hole or the through hole is filled with solder, One or more passive elements or active elements are also electrically connected to the wiring layer.

  The flexible circuit board with a built-in multilayer component according to the present invention includes a wiring layer having an electrode portion formed of a conductor, a sheet-like insulating substrate provided with a via hole or a through hole at a predetermined position of a part of the wiring layer and the electrode portion, and A plurality of built-in component flexible circuit boards having one or more passive elements or active elements electrically connected to and placed on the wiring layer and filled with solder in via holes or through holes via a gap filling insulating sheet It has a configuration in which the sheets are stacked and formed integrally, and a configuration in which a hole larger than the area where the passive element or the active element is arranged is provided in the component built-in flexible circuit board and the gap filling insulating sheet.

  With these configurations, each component-embedded flexible circuit board is completed with the solder filled in the through holes and via holes, so that it is possible to easily integrate a plurality of unit-part-embedded flexible circuit boards. With regard to electrical connection, high reliability can be obtained. In addition, by using through holes and via holes filled with solder, highly reliable electrical connections can be made at will, eliminating the need for unintentional routing of wiring, and built-in multilayer components suitable for high-speed data processing functions A flexible circuit board and a laminated wiring board can be provided. In addition, the size of the flexible circuit board with built-in multilayer components is reduced by providing a hole larger than the area where passive elements or active elements are arranged in the flexible circuit board with embedded parts and the gap-filling insulating sheet, and arranging large active elements between the layers. , Lighter and thinner.

  The method for manufacturing a flexible circuit board with a built-in multilayer component according to the present invention includes a step of forming a wiring layer having an electrode portion on a sheet-like insulating substrate with a conductor, and a via hole at a predetermined position of the wiring layer and the electrode portion. A process of providing a through hole, a process of mounting one or more passive elements or active elements connected to a wiring layer, and filling a via hole or a through hole with solder to fill a sheet-like insulating substrate with a flexible component The method includes a step of forming on a circuit board, and a step of integrally forming a component-embedded flexible circuit board by stacking a plurality of pieces with a gap filling insulating sheet interposed therebetween.

  This method makes electrical connection between layers between component built-in flexible circuit boards with via holes and through holes filled with solder inside, making it easy to make highly reliable interlayer electrical connections with low resistance and flexible built-in multilayer components. In making the circuit board, it is possible to adopt a configuration and method in which the flexible circuit boards with built-in components are stacked and integrally molded. In addition, since the flexible circuit board with built-in components can be formed in parallel in different manufacturing devices, the structural design of the flexible circuit board with built-in laminated components can be compared to the conventional sequential lamination method. In addition, the degree of freedom in the process design of the manufacturing process is increased, and the effects of improving productivity and production yield can be obtained.

  As described above, according to the present invention in which an electrical circuit is connected by heating and welding a via hole or a through hole filled with solder inside, a highly reliable electrical connection with a low resistance value can be achieved in the shortest distance. In addition, since the component-embedded flexible circuit board can be easily laminated, a configuration and method of stacking unit component-embedded flexible circuit boards and integrally forming them can be employed in making the multilayer component-embedded flexible circuit board. In addition, since flexible circuit boards with built-in unit parts can be made in various configurations in parallel with different manufacturing equipment, the degree of freedom in structural design of the flexible circuit board with built-in parts and the design freedom in the production process are high. Thus, the process is simplified and the reliability of the process is improved. As a result, an effect of improving productivity and production yield can be obtained, and a highly reliable flexible circuit board with a built-in multilayer component and a manufacturing method thereof can be provided by a simple process.

  The flexible circuit board with a built-in multilayer component of the present invention makes it possible to provide a low-cost flexible circuit board with a built-in multilayer component for an IC card that requires high-speed processing of data, for example, and is important to have thinness and flexibility. To do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
1A and 1B are a cross-sectional view and a plan view showing the configuration of a unit component built-in flexible circuit board that constitutes a multilayer component built-in flexible circuit board according to Embodiment 1 of the present invention.

  In FIG. 1, a wiring layer 2 having an electrode portion 3 is formed on the upper surface of a thin resin sheet-like insulating substrate 1 having flexibility and heat resistance. A coil 11 serving as an inductor connected to the wiring layer 2, a capacitor 10 serving as a capacitor, and a resistor 12 are placed. The capacitor 10 includes an upper electrode 10a, a lower electrode 10b, and a dielectric 10c. The capacitor 10 is connected to the wiring layer 2 by the upper electrode 10a and the lower electrode 10b, and the resistor 12 is connected by the resistance electrodes 12a and 12b. The electrode part 3 of the wiring layer 2 is mainly provided with a through hole 4 having a diameter of 100 μm, for example, and a via hole 5 having a diameter of 50 μm is provided at a predetermined position of the wiring layer 2. The through hole 4 and the via hole 5 are selectively used depending on the connection purpose. When forming the power supply circuit, the through-hole 4 having a large inner diameter is mainly used to connect between the wiring layers 2 of adjacent flexible circuit boards with built-in unit parts, or passive elements or active elements (not shown in FIG. 1). ) Is used to use the via hole 5. Each unit component built-in flexible circuit board 14 is completed with the solder 7 filled in the through holes 4 and via holes 5. A passive element 8 mounted on the unit component built-in flexible circuit board 14 can be mounted with a capacitor 10 serving as an electric capacity, a coil 11 serving as an inductor, and a resistor 12 alone or in combination, and an active element. A semiconductor such as an LSI of a BGA (Ball Grid Array) type can be mounted as 9. However, it is desirable to form a semiconductor alone because of its characteristics. Then, various types of elements and components are mounted to form unit component built-in flexible circuit boards 14 having different configurations. The sheet-like insulating substrate 1 used for any of the unit component built-in flexible circuit boards 14 has flexibility, and these unit component built-in flexible circuit boards 14 can be manufactured in parallel in the process. A plurality of unit component built-in flexible circuit boards 14 having different configurations are laminated to form a laminated component built-in flexible circuit board. As one of the unit component built-in flexible circuit boards 14, only the wiring layer 2 in which a via hole 5 filled with solder 7 and a through hole 4 are provided at a predetermined position of the wiring layer 2 having the electrode portion 3 is provided. May be.

  FIG. 2 is a diagram showing an example of a process of filling solder into the through holes and via holes of the unit component built-in flexible circuit board according to Embodiment 1 of the present invention. In FIG. 2, each step shows an enlarged cross-sectional view on the right side of each hole portion of the through hole and via hole of the flexible circuit board with a built-in unit component in each step. With reference to FIG. 2, a procedure for forming the through hole 4 and the via hole 5 of the unit component built-in flexible circuit board 14 constituting the laminated circuit board built-in flexible circuit board according to Embodiment 1 of the present invention will be briefly described. First, for example, a wiring layer 2 having an electrode portion 3 is formed into a film using a conductive material such as copper on a thin sheet-like insulating substrate 1 made of a resin having heat resistance such as polyimide (step Sa). For example, a method such as sputtering deposition can be used to form the wiring layer 2 having the electrode portion 3. Next, the through hole 4 and the via hole 5 are formed by laser processing (step Sb). Subsequently, the conductive layer 6 is vapor-deposited and formed on the inner surface of the hole by using a well-known sputtering technique with a conductive material such as copper (step Sc). Thereafter, cream solder is applied by printing or dropped by a dispenser, and then heated and melted to fill the solder 7 by reflow (step Sd).

  Whether the solder 7 is filled in the through hole 4 or the via hole 5 is whether the solder 7 is filled in the hole by applying the cream solder by printing or dripping it with a dispenser and then filling the hole with the solder 7. Depending on the number and density of via holes 5, both methods can be used properly. A jig that is made of a material with good wettability on the solder 7 and has an outer diameter longer than the depth of the through hole 4 or the via hole 5 and smaller than the inner diameter of the through hole 4 or the via hole 5. A method by dipping is also conceivable in which the solder 7 is pulled up from the solder bath to the inside of the through hole 4 or the via hole 5 using the solder bath. The solder 7 is preferably a low melting point lead-free solder.

  In addition, the through hole and via hole of the flexible circuit board with built-in unit components constituting the laminated circuit board with flexible circuit in Embodiment 1 of the present invention can have a slightly different shape from the above-described shape.

  FIG. 3 is a cross-sectional view showing another shape of the state of filling the through holes and the via holes of the unit component built-in flexible circuit board constituting the multilayer component built-in flexible circuit board according to Embodiment 1 of the present invention. The solder 7 is filled so that the through hole 4 or the via hole 5 provided in the wiring layer 2 or the electrode part 3 is filled with the solder 7 higher than the upper surface of the wiring layer 2 or the electrode part 3. is there. By configuring the filling state of the solder 7 into the through hole 4 and the via hole 5 so as to be higher than the upper surface of the wiring layer 2 or the electrode part 3, the adjustment of the stacking height direction when designing the flexible circuit board with a built-in multilayer component And reliability of electrical connection can be improved.

  In the above description, polyimide is taken as an example of the resin-made thin sheet-like insulating substrate 1 having flexibility and heat resistance. However, the present invention is not limited to this. In addition to polyimide, heat-resistant organic films such as polyamideimide and polyphenylene sulfide and liquid crystal polymers can be used for the sheet-like insulating substrate 1. Moreover, not only resin but an inorganic material film can also be used, and it is also possible to apply the above heat-resistant organic material or inorganic material to a thin metal foil or metal film and apply it to the sheet-like insulating substrate 1. The thickness of the sheet-like insulating substrate 1 is preferably 25 μm to 125 μm from the viewpoint of processability in the process, but considering the operability, a thickness of 75 μm ± 15 μm is more preferable.

  Further, in the formation of the wiring layer 2 having the electrode portion 3, an example in which a conductor material such as copper is formed by sputtering deposition is described, but the conductor material is not limited to copper, It is also possible to use a metal such as aluminum, gold, platinum or palladium, or an alloy material of these metals. As the film forming method, film forming techniques such as vacuum vapor deposition and electron beam (EB) vapor deposition can be used in addition to sputter vapor deposition. The electrode part 3 and the wiring layer 2 are formed from these formed thin films, and it is desirable to form each of them in a thickness of 0.1 μm to 1.0 μm.

  In addition, since the electrode portion of the wiring layer 2 is wider than the line width of the wiring layer 2, a hole having a larger inner diameter than the wiring layer 2 portion can be formed. The electrode portion 3 is mainly provided with a through hole 4 having a diameter of about 100 μm, and is used for connection of a power circuit or the like. When it is necessary to further reduce the current density, the inner diameter of the through hole 4 can be increased by designing the area of the electrode portion 3 to be large. When it is necessary to connect at the shortest distance or locally, it is possible to provide a via hole 5 having a diameter of about 50 μm in the wiring layer 2 portion, and to use both depending on the purpose of connection.

  Next, the laminated component built-in flexible circuit board according to the first embodiment of the present invention using the unit component built-in flexible circuit board will be described.

  FIG. 4 is a cross-sectional view of the flexible circuit board with a built-in multilayer component according to Embodiment 1 of the present invention. FIG. 5 is an exploded cross-sectional view showing details of the configuration of the multilayer component built-in flexible circuit board shown in FIG. The multilayer component built-in flexible circuit board 15 according to the first embodiment will be described with reference to FIGS. 4 and 5, the lower unit component built-in flexible circuit board 16 is mounted with a capacitor 10 as an electric capacity, a coil 11 as an inductor, and a resistor 12 as passive elements 8. The lower unit component built-in flexible circuit board 16 has substantially the same configuration as the unit component built-in flexible circuit board 14 of FIG. Further, as will be described later, since the gap-filling insulating sheet 20 serves as a spacer and an adhesive layer between each unit component built-in flexible circuit board, the lower unit component built-in flexible circuit board 16 and the first first The intermediate unit component-embedded flexible circuit board 17 is interposed. It is assumed that at least the coil 11 and other passive elements 8 are mounted on the first intermediate unit component built-in flexible circuit board 17. Further, the second intermediate unit component built-in flexible circuit board 18 also shows only the passive element 8 in FIGS. 4 and 5, but it is assumed that a capacitor and a resistor are mounted as the passive element 8. In the upper unit component built-in flexible circuit board 19, a capacitor is mounted as a passive element, and a via hole for mounting a BGA type LSI 13 as an active element is provided. In the example shown here, the coil 11 placed on the lower unit component built-in flexible circuit board 16 and the coil 11 placed on the first intermediate unit component built-in flexible circuit board 17 are connected by the via hole 11a and the via hole 22a. An example of increasing the number of turns is shown. That is, the coil 11 is connected to a circuit constituted by the wiring layer 2 through the via hole 22b and the via hole 23b, and functions as a four-turn coil. These four types of unit component built-in flexible circuit boards (lower unit component built-in flexible circuit board 16, first intermediate unit component built-in flexible circuit board 17, second intermediate unit component built-in flexible circuit board 18, and upper unit component built-in flexible circuit board 19 ) The gap filling insulating sheet 20 is interposed between the layers and laminated, and heat-pressed and molded integrally to form the laminated component built-in flexible circuit board 15. By laminating the four types of unit component built-in flexible circuit boards, the multilayer component built-in flexible circuit board 15 having an overall thickness of about 500 to 650 μm can be obtained. Since each unit component built-in flexible circuit board and the gap filling insulating sheet 20 have flexibility, naturally, the laminated component built-in flexible circuit board 15 also has flexibility. A power supply circuit and a ground circuit are configured by connecting the wiring layers 2 of all the flexible circuit boards with built-in unit components by the electrode portions 3 through the through holes 4.

  The gap filling insulating sheet 20 serves as a spacer and an adhesive layer between the flexible circuit boards with built-in unit components. A BGA type LSI 13 is mounted as an active element on the flexible circuit board 19 with a built-in upper unit component. A semiconductor bare chip centering on a microcomputer is often used as the active element. However, as described above, it is desirable that the semiconductor element is formed alone because of its characteristics.

  Further, when designing the laminated device itself and its wiring circuit, it may be necessary to connect locally. This is different from the case where all the flexible circuit boards with built-in unit components are connected in common, such as a power supply circuit. The passive elements are connected to each other, the active elements and the passive elements are connected in the shortest distance, and the wiring length is made as short as possible. This is the case where adjacent flexible circuit boards with built-in unit parts are connected at necessary places, or mounts for mounting BGA type LSIs are formed.

  Next, a passive element or an active element placed on the flexible circuit board with a built-in unit component constituting the laminated circuit board with a built-in multilayer component of the present invention will be briefly described. FIG. 6 is a cross-sectional view showing an example in which various passive elements and active elements are mounted on a flexible circuit board with a built-in unit component. FIG. 6A is characterized in that the passive element or the active element is a chip-like element. An example in which a chip-like capacitor 10 is placed on a wiring layer 2 provided on a sheet-like insulating substrate 1 is shown. Instead of the chip-shaped capacitor 10, a chip-shaped passive element such as a chip-shaped resistor or a chip-shaped inductor, a chip-shaped active element such as a chip-shaped transistor, a diode, or a small IC can naturally be used.

  FIG. 6B is characterized in that the passive element or the active element is a sheet-like element called a so-called thick film element. An example in which a sheet-like capacitor 10 is placed on the wiring layer 2 provided on the sheet-like insulating substrate 1 is shown. In this case as well, it is needless to say that other sheet-like passive elements or sheet-like active elements can be used as described with reference to FIG.

  On the other hand, FIG. 6C is characterized in that passive elements and active elements are directly formed on the surface of the sheet-like insulating substrate 1. A capacitor 10 is formed and placed in connection with the wiring layer 2 provided on the sheet-like insulating substrate 1. A lower electrode 10b of the capacitor 10, a dielectric 10c, and an upper electrode 10a of the capacitor 10 are sequentially formed. In this case as well, other passive elements or active elements can be used in the same manner as described in FIGS. 6 (a) and 6 (b).

  Next, a manufacturing procedure of the multilayer component built-in flexible circuit board according to Embodiment 1 of the present invention will be described. FIG. 7 is a flowchart showing a manufacturing process of the multilayer component built-in flexible circuit board according to Embodiment 1 of the present invention. Here, the procedure for forming the through hole 4 and the via hole 5 of the unit component built-in flexible circuit board 14 constituting the laminated component built-in flexible circuit board 15 according to the first embodiment of the present invention will be described with reference to FIG. The first half of FIG. 7 is the same as that of FIG. 2, and therefore, the procedure for forming the unit component built-in flexible circuit board 14 portion, that is, the step of forming the wiring layer 2 having the electrode portion 3 on the sheet-like insulating substrate 1 ( Step S1), a step of processing the through hole 4 and the via hole 5 at a predetermined position of the wiring layer 2 having the electrode portion 3 (Step S2), and a step of forming the conductive layer 6 on the inner surface of the through hole 4 and the via hole 5 (Step S3), a step of placing one or more passive elements 8 connected to the wiring layer 2 (step S4), a step of applying or applying the solder 7 with a dispenser (step S5) Heated and melted steps to complete the unit component-embedded flexible circuit board 14 is filled inside the through-hole 4 and the via hole 5 to (step S6) is not described in detail.

  The above is the process up to the formation of the flexible circuit board with a built-in unit component, and the process for forming the flexible circuit board with a built-in multilayer component is performed thereafter. A plurality of different unit component built-in flexible circuit boards completed for each predetermined configuration through the above-described step S1 to step S6 are combined and arranged in the arrangement hole of the unit sheet arrangement jig for integral molding via the gap filling insulating sheet. Set up. At this time, a via hole or a through hole is used for alignment of the flexible circuit boards with built-in unit components (step S7). Next, the unit sheet placement jig is heated, pressed by the pressing jig from above the placement hole, and a plurality of unit component built-in flexible circuit boards and the gap filling insulating sheet are integrally formed by heating and pressing (step S8). In the last step, an active element is placed (step S9). The placement of the active element is preferably a final process because of its characteristics as a part, but can also be performed simultaneously with the integral molding as described above. It can also be placed on a flexible circuit board with built-in unit parts. When an active element is placed on the unit component built-in flexible circuit board, the active element is placed in the step S4, or depending on the placement method, the active element is placed between the step S6 and the step S7. A process will be provided.

  FIG. 8 is a longitudinal cross-sectional view of a multilayer component built-in flexible circuit board of another configuration according to Embodiment 1 of the present invention. The flexible circuit board 16 with a built-in lower unit component, the flexible circuit board 17 with a built-in first intermediate unit component, the flexible circuit board 18 with a built-in second intermediate unit component, and the flexible circuit board 19 with a built-in unit unit component 19 The laminated component built-in flexible circuit board 15 is formed by interposing a gap-filling insulating sheet 20 therebetween and integrally forming the laminated component built-in flexible circuit board 15, as described with reference to FIGS. 4 and 5. It is the same as that of the structure. The same component parts and members as those described in FIGS. 1 to 6 are denoted by the same reference numerals.

  In FIG. 8, a BGA type LSI 13 that is an active element is placed on the mount portion formed by the via hole 5 of the sheet-like insulating substrate 1 on the first intermediate unit component built-in flexible circuit board 17. The upper unit component built-in flexible circuit board 19, the second intermediate unit component built-in flexible circuit board 18, and the gap filling insulating sheet 20 are provided with relief holes 21. When a large active element such as an LSI is placed on an arbitrary flexible circuit board with built-in unit parts, such a large active element and a three-dimensional space such as another flexible circuit board with built-in unit parts 14 and a gap-filling insulating sheet 20 are used. By providing a clearance hole 21 that becomes a vacant space in the overlapping portion, it is possible to place a large active element such as an LSI on the flexible circuit board with a built-in unit component at any position. is there.

  As already described in the multilayer circuit board 15 having the configuration shown in FIGS. 4 and 5, a large active element such as a BGA type LSI 13 can be stacked after being formed on the multilayer circuit board 15. Although it is desirable, if the unit component built-in flexible circuit board 14 and the gap filling insulating sheet 20 provided with an empty space are used, they can be stacked simultaneously in the integral molding process, or placed on the unit part built-in flexible circuit board 14. You can also. As shown in FIG. 4, the thickness of the multilayer component built-in flexible circuit board 15 is mainly the same as that of LSI in the configuration in which a large active element such as LSI is mounted on the upper unit component built-in flexible circuit board 19. Although it is controlled by the height dimension of the large-sized active element, by adopting the configuration of the flexible circuit board with a built-in multilayer component according to the first embodiment of the present invention, a thinner flexible circuit board with a built-in multilayer component can be easily obtained. Can be provided.

  As described above, the flexible circuit board with a built-in multilayer component according to the first embodiment of the present invention mounts an active element such as an LSI by using a via hole filled with solder in the flexible circuit board with a built-in unit component constituting the flexible circuit board with a built-in multilayer component. Therefore, it is very easy to mount an active element such as an LSI. In this configuration, it can be placed at the same time in the integral molding process, or after integral molding. Therefore, the process configuration is easier than in the sequential lamination method, and the productivity is improved. Further, since the electrical connection is realized by melting the solder in the through hole or via hole portion, it is possible to provide a flexible circuit board with a built-in multilayer component with high connection reliability.

(Embodiment 2)
FIG. 9 is a cross-sectional view showing the configuration of a unit component built-in flexible circuit board that constitutes the multilayer component built-in flexible circuit board according to Embodiment 2 of the present invention. This unit component built-in flexible circuit board is greatly different from the unit component built-in flexible circuit board constituting the laminated component built-in flexible circuit board in the first embodiment. That is, in the flexible circuit board with built-in unit components constituting the flexible circuit board with built-in multilayer component in the first embodiment, the wiring layer 2 having the electrode portion 3 is formed on the sheet-like insulating substrate 1, and the passive component or active component is formed. Whereas only one side was placed, the unit component built-in flexible circuit board constituting the laminated component built-in flexible circuit board in the second embodiment of the present invention is provided on both sides of the sheet-like insulating substrate 1. A wiring layer 2 having an electrode portion 3 is formed on the substrate, and passive components or active components are placed thereon. Hereinafter, the structure of the unit component built-in flexible circuit board constituting the multilayer component built-in flexible circuit board in Embodiment 2 of the present invention will be described with reference to FIG. In FIG. 9 as well, the same elements, components, and members as those shown in FIGS. 1 to 6 and FIG.

  In FIG. 9, a wiring layer 2 having electrode portions 3 is formed on both front and back surfaces of a resin-made thin sheet-like insulating substrate 1 having flexibility and heat resistance, and through holes 4 are formed at predetermined positions. A via hole 5 is provided, a conductive layer 6 is formed on the inner surface of the through hole 4 and the via hole 5, and then solder 7 is filled. Since these structures and manufacturing processes are almost the same as those in the first embodiment, detailed description is omitted to avoid duplication. Passive elements and active elements can be placed on the flexible circuit board with built-in unit parts of this double-sided configuration, but FIG. 9 shows an example in which only the wiring layer 2 is formed. Since the configuration and manufacturing process for mounting are almost the same as those of the first embodiment, detailed description is omitted to avoid duplication.

  In addition, the through hole and via hole of the flexible circuit board with built-in unit components that constitute the flexible circuit board with built-in multilayer component in the second embodiment of the present invention are flexible in the unit component built-in flexible circuit board with a built-in multilayer component in the first embodiment. As in the case of the through hole and via hole of the circuit board, FIG. 10 shows the filling state of solder into the through hole and via hole of the flexible circuit board with built-in unit components constituting the laminated circuit board with flexible circuit in Embodiment 2 of the present invention. As shown in the cross-sectional view, the solder is filled so that the filling state of the solder 7 into the through hole 4 or the via hole 5 provided in the wiring layer 2 or the electrode part 3 is higher than the upper surface of the wiring layer 2 or the electrode part 3. It is possible to fill. The filling state of the solder 7 into the through hole 4 or the via hole 5 on the flexible circuit board with built-in unit parts formed on the front and back surfaces of the sheet-like insulating substrate 1 on which the wiring layer 2 having the electrode portion 3 is formed. By configuring so as to be higher than the upper surface of 3, it is possible to facilitate adjustment in the height direction of the stack and to improve the reliability of electrical connection when designing the flexible circuit board with a built-in multilayer component.

  As described above, the multilayer component built-in flexible circuit board according to the second embodiment of the present invention is a wiring having the electrode parts 3 on both the front and back sides of the sheet-like insulating substrate 1 in the unit component built-in flexible circuit board. Since the layer 2 is formed and the through hole 4 and the via hole 5 are provided at predetermined positions, a local short-distance connection can be facilitated, electrical connection can be made with low resistance, and the number of turns of the coil can be increased. Since it can be made easier, the utility value is increased in a high-frequency device. Furthermore, the configuration that can use both surfaces of the sheet-like insulating substrate 1 increases the degree of freedom in design of the structure and the circuit, and can be expected to have a great effect in reducing the thickness, size, and weight of the device.

  As described above, in the component built-in flexible circuit board and the multilayer component built-in flexible circuit board according to the present invention, the electrical circuit is connected by heating and welding the via hole or the through hole filled with solder inside, and it is low in the shortest distance. A highly reliable electrical connection can be achieved with a resistance value, and a flexible circuit board with built-in components can be easily stacked. For stacking, a configuration and method are adopted in which the flexible circuit boards with built-in unit components are stacked and integrally molded. In addition, the flexible circuit board with built-in unit parts constituting the flexible circuit board with built-in parts can be freely designed in the structure of the flexible circuit board with built-in parts by making various configurations in parallel with different manufacturing equipment. The degree of freedom of design and production process is increased, the process is simplified, and at the same time the process reliability is improved. As a result, it is possible to provide an effect of improving productivity and production yield, and to provide a highly reliable flexible circuit board with a built-in multilayer component and a manufacturing method thereof with a simple process. For example, high-speed data processing is required. Therefore, it is suitable for inexpensively providing a flexible circuit board with a built-in multilayer component for a portable information device such as a PDA, a cellular phone, or an IC card, which is important to have thinness and flexibility.

(A), (b) is sectional drawing and top view which show the structure of the unit component built-in flexible circuit board which comprises the multilayer component built-in flexible circuit board in Embodiment 1 of this invention The figure which shows an example of the process which fills the inside of each hole of the through hole of a unit component built-in flexible circuit board and the via hole in Embodiment 1 of this invention. Sectional drawing which shows another shape of the filling state of the solder to the inside of the through-hole and via hole of the flexible circuit board with a built-in unit component in Embodiment 1 of this invention Sectional drawing of the multilayer component built-in flexible circuit board in Embodiment 1 of this invention FIG. 4 is an exploded sectional view showing details of the configuration of the flexible circuit board with a built-in multilayer component shown in FIG. (A), (b), (c) is sectional drawing which shows the example which mounts and forms various passive elements and active elements in the flexible circuit board with a built-in unit component. The flowchart which shows the manufacturing process of the flexible circuit board with a laminated component in Embodiment 1 of this invention Vertical section of a flexible circuit board with a built-in multilayer component having another configuration according to the first embodiment of the present invention Sectional drawing which shows the structure of the flexible circuit board with a built-in unit component which comprises the flexible circuit board with a laminated component in Embodiment 2 of this invention Sectional drawing which shows the filling state of the solder to the inside of the through hole and via hole of the flexible circuit board with a built-in unit component in Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet-like insulating substrate 2 Wiring layer 3 Electrode part 4 Through hole 5, 11a, 22a, 22b, 23b Via hole 6 Conductive layer 7 Solder 8 Passive element 9 Active element 10 Capacitor 10a Upper electrode 10b Lower electrode 10c Dielectric body 11 Coil 12 Resistance 12a, 12b Resistive electrode 13 BGA type LSI
14 Flexible circuit board with built-in unit parts 15 Flexible circuit board with built-in multilayer parts 16 Flexible circuit board with built-in lower unit parts 17 First flexible circuit board with built-in intermediate unit parts 18 Second flexible circuit board with built-in intermediate unit parts 19 Flexible circuit board with built-in upper unit parts 20 Insulation sheet for gap filling 21 Relief hole

Claims (10)

A wiring layer having an electrode portion formed of a conductor, a sheet-like insulating substrate provided with a via hole or a through hole at a predetermined position of the wiring layer and at a predetermined position of the electrode portion, and electrically connected to the wiring layer One or more passive elements or active elements
A flexible circuit board with a built-in component, wherein the via hole or the through hole is filled with solder. The component built-in flexible circuit board according to claim 1, wherein the passive element or the active element is a chip-like element. The component built-in flexible circuit board according to claim 1, wherein the passive element or the active element is a sheet-like element. The component built-in flexible circuit board according to claim 1, wherein the passive element is directly molded and mounted on the surface of the sheet-like insulating substrate. 2. The component built-in flexible circuit board according to claim 1, wherein the active element is a thin film semiconductor formed and mounted directly on the surface of the sheet-like insulating substrate. 2. The component according to claim 1, wherein the solder filled in all or part of the via hole or the through hole is formed to be higher than an upper surface of the wiring layer or the electrode portion. Built-in flexible circuit board. The wiring layer having the electrode part is formed of the conductor on both upper and lower surfaces of the sheet-like insulating substrate, and the via hole or the through hole is provided at a predetermined position of the wiring layer and the electrode part, 7. The solder according to claim 1, wherein the solder is filled in a via hole or the through hole, and one or more of the passive elements or the active elements are electrically connected and placed on the wiring layer. The component built-in flexible circuit board according to claim 1. A wiring layer having an electrode portion formed of a conductor, a sheet-like insulating substrate provided with a via hole or a through hole at a predetermined position of the wiring layer and at a predetermined position of the electrode portion, and electrically connected to the wiring layer One or more passive elements or active elements, and a plurality of built-in component flexible circuit boards in which solder is filled in the via holes or the through holes are stacked and integrated with a gap filling insulating sheet. A flexible circuit board with built-in laminated parts. 9. The multilayer component-embedded flexible circuit board according to claim 8, wherein a hole larger than an area in which the passive element or the active element is disposed is provided in the component-embedded flexible circuit board and the gap filling insulating sheet. Forming a wiring layer having an electrode portion on a sheet-like insulating substrate with a conductor;
A step of providing a via hole or a through hole at a predetermined position of a part of the wiring layer and the electrode part;
Placing one or more passive or active elements connected to the wiring layer;
Filling the via hole or the through hole with solder and forming the sheet-like insulating substrate on a component-embedded flexible circuit board;
And a step of integrally forming a plurality of the component-embedded flexible circuit boards through a gap-filling insulating sheet.

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