JP2012169520A - Circuit device - Google Patents

Abstract

A circuit device with improved heat dissipation is provided.
A hybrid integrated circuit device 10A according to the present invention includes a circuit board 12, a control element 23 and a chip element 24 disposed on the upper surface of the circuit board 12, and an opening 18 in which the circuit board 12 is partially opened. And a mounting board 28 for closing the opening 18 from the lower surface, and a power element 22 mounted on the upper surface of the mounting board 28. By mounting the power element 22 on the mounting board 28 made of a material having higher thermal conductivity than the circuit board 12, the heat generated from the power element 22 can be discharged to the outside through the mounting board 28. .
[Selection] Figure 1

Description

  The present invention relates to a circuit device, and more particularly to a circuit device having improved heat dissipation.

  With reference to FIG. 4, a configuration of a hybrid integrated circuit device 100 will be described as an example of a conventional circuit device (Patent Document 1). First, a conductive pattern 103 is formed on the surface of a substrate 101 made of a metal such as aluminum via an insulating layer 102 made of resin, and a circuit element is fixed to a desired portion of the conductive pattern 103 so that a predetermined electric circuit is formed. A circuit is formed. Here, a semiconductor element 105A and a chip element 105B are employed as circuit elements. The semiconductor element 105 </ b> A is, for example, a transistor or a diode, and the electrode on the upper surface is connected to the predetermined conductive pattern 103 via the metal thin wire 107, and the electrode on the back surface is connected to the conductive pattern 103. On the other hand, the chip element 105B, which is a capacitor or a resistor, has electrodes at both ends bonded to a predetermined conductive pattern 103 via a bonding material 106 such as solder. In addition, the sealing resin 108 has a function of sealing an electric circuit formed on the surface of the substrate 101. Furthermore, the lead 109 functions as an external connection terminal of the entire device, the inner end is fixed to the conductive pattern 103 formed in a pad shape, and the outer end is led out from the sealing resin 108 to the outside.

  In the hybrid integrated circuit device 100 having such a configuration, each circuit element is mounted on the upper surface of the substrate 101 made of metal. Therefore, even if the semiconductor element 105A generates heat under an operating condition, the generated heat is applied to the substrate 101. It is released to the outside through

JP 2007-036014 A

  However, when an element that generates a large amount of heat, such as a power element that switches large currents of several tens of amperes, is employed as a circuit element, the hybrid integrated circuit device 100 having the above-described configuration has a problem of insufficient heat dissipation.

  Specifically, for example, the path through which the heat generated from the semiconductor element 105A reaches the outside is the order of the conductive pattern 103, the insulating layer 102, the substrate 101, and the sealing resin 108. Among these, since the conductive pattern 103 and the substrate 101 are made of metal, the thermal conductivity is good. However, since the insulating layer 102 and the sealing resin 108 are made of a resin material such as an epoxy resin, the thermal conductivity is bad. As described above, the fact that the portion made of resin is included in the path through which the heat of the semiconductor element 105A is released to the outside has hindered further improvement in heat dissipation.

  Further, when the lower surface of the substrate 101 is exposed to the outside, the heat dissipation is improved by the amount of the sealing resin 108 covering the back surface. However, even in this case, since the insulating layer 102 covering the upper surface of the substrate 101 exists in the heat path, there is a limit to improvement in heat dissipation. Furthermore, in order to improve the thermal conductivity of the insulating layer 102 itself, the insulating layer 102 contains an inorganic filler such as silica, but even if such measures are taken, the thermal conductivity of the insulating layer 102 is inferior to that of a metal.

  Further, the hybrid integrated circuit device 100 described above may not have sufficient pressure resistance. Specifically, the substrate 101 made of a metal that is a conductive material and the conductive pattern 103 are insulated by an insulating layer 102 interposed therebetween. However, for example, when a voltage of about 1000 V to 2000 V is applied to the conductive pattern 103, the insulating layer 102 made of a resin material such as an epoxy resin may break down, and the conductive pattern 103 and the substrate 101 may be short-circuited. It was.

  The present invention has been made in view of the above problems, and a main object of the present invention is to provide a circuit device having further improved heat dissipation.

  The circuit device of the present invention includes a circuit board having a conductive pattern disposed on an upper surface, an opening partly opening the circuit board, and a mounting part disposed below the circuit board so as to overlap the opening part. It is characterized by comprising a substrate and a semiconductor element disposed on the upper surface of the mounting substrate and electrically connected to the conductive pattern.

  According to the present invention, an opening is provided in a substrate on which a circuit element is mounted, a mounting substrate made of a material having excellent thermal conductivity is disposed below the opening, and a semiconductor element is mounted on the upper surface of the mounting substrate. ing. By doing in this way, the heat generated from the semiconductor element is immediately released to the outside through the mounting substrate having excellent thermal conductivity. Therefore, overheating of the semiconductor element during operation is suppressed, and its malfunction and characteristic deterioration are suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the hybrid integrated circuit device as a circuit device of this invention, (A) is a perspective view, (B) is sectional drawing, (C) is a cross section which shows the hybrid integrated circuit device of another form. FIG. It is a figure which shows the hybrid integrated circuit device as a circuit device of this invention, (A)-(D) is sectional drawing which shows the hybrid integrated circuit device of another form. It is a graph which shows the result of having measured the thermal resistance of the hybrid integrated circuit device of this form. It is sectional drawing which shows the hybrid integrated circuit device of background art.

  With reference to FIG. 1, the configuration of a hybrid integrated circuit device 10A will be described as an example of the circuit device of the present invention. 1A is a perspective view showing a hybrid integrated circuit device 10A, FIG. 1B is a cross-sectional view thereof, and FIG. 1C is a cross-sectional view showing another form of a hybrid integrated circuit device 10B. is there.

  Referring to FIGS. 1A and 1B, a hybrid integrated circuit device 10A includes a circuit board 12 in which a hybrid integrated circuit composed of a conductive pattern 16 and circuit elements is incorporated on an upper surface, and a circuit board 12 partially An opening 18 that is open, a mounting substrate 28 disposed below the circuit board 12 so as to overlap the opening 18, and a power element 22 (semiconductor element) mounted on the mounting substrate 28. . Further, the hybrid integrated circuit device 10 </ b> A includes a sealing resin 30 and a lead 14 that is fixed to the conductive pattern 16 and the other end is led out from the sealing resin 30.

  Specifically, the circuit board 12 is a board on which a conductive pattern 16 for connecting circuit elements to each other is formed on the upper surface. As a material of the circuit board 12, a resin material such as glass epoxy resin, a ceramic substrate, or a metal substrate such as aluminum is employed. When a metal substrate is employed as the circuit board 12, the upper surface of the circuit board 12 is covered with an insulating layer made of a resin filled with a filler such as alumina, and a conductive pattern 16 is formed on the upper surface of the insulating layer. The The specific size of the circuit board 12 is, for example, about vertical × horizontal = 60 mm × 80 mm, and the thickness is about 1.0 mm to 2.0 mm.

  The conductive pattern 16 is made of a metal such as copper having a thickness of about 35 μm to 70 μm, and is formed on the upper surface of the circuit board 12 so as to form a predetermined electric circuit. The conductive pattern 16 includes an island to which circuit elements are fixed, a pad to which a thin metal wire is connected, a pad to which a lead 14 is fixed, and a wiring portion that connects these to each other. Although a single-layer conductive pattern 16 is shown here, a multilayer conductive pattern 16 laminated via an insulating layer may be formed on the upper surface of the circuit board 12.

  As a circuit element electrically connected to the conductive pattern 16, an active element or a passive element can be generally employed. Specifically, transistors, LSI chips, diodes, chip resistors, chip capacitors, inductances, and the like can be employed as circuit elements. Referring to FIG. 1A, a control element 23 (LSI), a chip element 24 and the like are fixed to the upper surface of the circuit board 12 on the upper surface of the circuit board 12. On the other hand, the power element 22 such as a MOSFET is disposed inside the opening 18, and this matter will be described later with reference to FIG.

  The sealing resin 30 is formed so as to seal the circuit board 12 and the circuit elements fixed to the upper surface thereof. The sealing resin 30 is made of a thermosetting resin such as an epoxy resin mixed with a filler, and is formed by transfer molding.

  The lead 14 is fixed to a pad made of the conductive pattern 16 along the opposite side of the circuit board 12 and functions as an input / output terminal of the hybrid integrated circuit device 10A. Referring to FIG. 1A, a large number of leads 14 are provided along the side of the right circuit board 12 on the paper surface, but the leads 14 are fixed along two opposing sides. Also good.

  The opening 18 is a part where the circuit board 12 is partially opened, and is opened in a rectangular shape with a size capable of accommodating the power element 22. The size of the opening 18 in plan view is, for example, length × width = 0.4 cm or more and 1.2 cm or less. Such an opening 18 is formed by subjecting the circuit board 12 to pressing or grinding.

The mounting substrate 28 is a substrate disposed below the circuit board 12 in a region overlapping with the opening 18 of the circuit board 12, and is superior in thermal conductivity than the circuit board 12 and is made of an electrically insulating material. Become. As a specific material of the mounting substrate 28, for example, a ceramic substrate is employed. The size of the mounting substrate 28 in plan view is slightly larger than the opening 18, and the length × width = 0.5 cm or more and 1.5 cm or less. The thermal conductivity of the epoxy resin that is the material of the circuit board 12 is 0.2 [W · m ⁻¹ · K ⁻¹ ], whereas the thermal conductivity of the ceramic that is the material of the mounting board 28 is 30 [W · M ^-1 · K ^-1 ]. Further, the lower surface of the mounting substrate 28 is exposed to the outside from the sealing resin 30. Referring to FIG. 1A, two openings 18 are provided in the circuit board 12, and a power element 22 is disposed in these openings 18. Here, the mounting board 28 is in contact with the lower surface of the circuit board 12 so as to cover the entire area of the opening 18 from below, but the mounting board 28 may be provided so as to partially cover the opening 18. good.

  On the upper surface of the mounting substrate 28, a wiring pattern 32 is formed by patterning a metal foil such as copper into a predetermined shape. The electrode formed on the lower surface of the power element 22 is connected to the wiring pattern 32 via a conductive fixing material such as solder.

  The power element 22 mounted on the upper surface of the mounting substrate 28 is a semiconductor element through which a large current of, for example, 1 ampere or more passes, and specifically, a MOSFET, IGBT, bipolar transistor, or diode is employed. A plurality of these may be mounted on the mounting board 28.

  When a MOSFET is adopted as the power element 22, a drain electrode is disposed on the lower surface of the power element 22, and a source electrode and a gate electrode are provided on the upper surface. On the other hand, when IGBT is adopted as power element 22, a collector electrode is provided on the lower surface, and an emitter electrode and a gate electrode are disposed on the upper surface. When a bipolar transistor is adopted as the power element 22, a collector electrode is provided on the lower surface, and an emitter electrode and a base electrode are disposed on the upper surface.

  The power element 22 disposed on the upper surface of the mounting substrate 28 is connected to the conductive pattern 16 formed on the upper surface of the circuit substrate 12 through the fine metal wires 20. Specifically, for example, when the power element 22 is a MOSFET, the source electrode and the gate electrode provided on the upper surface of the power element 22 are formed from the conductive pattern 16 formed on the upper surface of the circuit board 12 via the fine metal wire 20. Connected to the pad. On the other hand, the drain electrode provided on the lower surface of the power element 22 is first electrically connected to the land-shaped wiring pattern 32 via solder. The wiring pattern 32 is connected to the pad-like conductive pattern 16 formed on the upper surface of the circuit board 12 through the fine metal wire 20.

  According to the hybrid integrated circuit device 10A of the present embodiment described above, the heat generated from the power element 22 can be released to the outside more efficiently than in the background art. Specifically, in this embodiment, a portion where the power element 22 is disposed is opened to provide an opening 18, and the power element 22 is fixed to the upper surface of the mounting substrate 28 disposed so as to close the opening. Yes. As a result, heat generated during operation of the power element 22 is favorably released to the outside via the wiring pattern 32 and the mounting substrate 28. In the conventional example, referring to FIG. 4, the insulating layer 102 covering the upper surface of the substrate 101 and the sealing resin 108 covering the lower surface of the substrate 101 exist in the heat dissipation path. However, in this embodiment, such a resin material (organic material) is not present in the heat dissipation path. That is, only the inorganic material of the wiring pattern 32 made of metal and the mounting board 28 made of ceramic exists in the heat dissipation path of the power element 22, and their thermal conductivity is very good as described above. Further, the solder used for fixing the power element 22 also serves as a heat dissipation path. However, since the solder is a metal material made of tin or the like, it has better thermal conductivity than the resin material. Furthermore, since the mounting board 28 is formed thinner than the circuit board 12, the thermal resistance is reduced accordingly. For the above reason, heat generated during operation of the power element 22 is immediately released to the outside, so that destruction and characteristic deterioration due to overheating of the power element 22 are suppressed.

  On the other hand, the power element 22 that generates a large amount of heat is not placed on the upper surface of the circuit board 12, and only elements that generate a relatively small amount of heat such as the control element 23 and the chip element 24 that control the switching of the power element 22 are arranged. Is done. Therefore, an inexpensive glass epoxy substrate that is inferior in heat dissipation can be adopted as the circuit board 12, and the cost can be reduced. Furthermore, since the glass epoxy substrate is a material excellent in workability, the opening 18 can be easily formed.

  Furthermore, in this embodiment, the substrate on which the power element 22 that generates a larger amount of heat than other elements is mounted and the substrate on which the other elements are mounted are separate substrates. Thereby, the amount of heat conducted from the power element 22 to other elements via the substrate is reduced. Therefore, the other element (control element 23) is prevented from being overheated by the heat generated from the power element 22.

  Furthermore, in the hybrid integrated circuit device 10A, the problem of dielectric breakdown described in the background art is avoided. Specifically, in this embodiment, since the mounting substrate 28 itself is made of ceramic which is an insulating material, it is not necessary to provide an insulating layer made of a resin that easily causes dielectric breakdown between the mounting substrate 28 and the wiring pattern 32. . Further, even when a voltage of about 1000 V to 2000 V is applied to the wiring pattern 32, the ceramic mounting substrate 28 is unlikely to cause dielectric breakdown. For this reason, the pressure resistance of the entire apparatus is improved.

  With reference to FIG. 1C, a configuration of a hybrid integrated circuit device 10B of another form will be described. The configuration of the hybrid integrated circuit device 10B is basically the same as that of the above-described device. The difference is that the back surface of the mounting substrate 28 is covered with the sealing resin 30. By doing in this way, since the sealing resin 30 exists in the path | route of the heat | fever which generate | occur | produced from the power element 22, heat dissipation is reduced a little. However, by forming the sealing resin 30 so that the lower surface of the mounting substrate 28 is also covered, the interface between the mounting substrate 28 and the sealing resin 30 is not exposed to the outside. Intrusion into the water is suppressed and moisture resistance is improved. Further, with respect to other forms described below, resin sealing may be performed so that the mounting substrate 28 is also covered in this way.

  A hybrid integrated circuit device according to another embodiment will be described with reference to FIGS. Since the hybrid integrated circuit device of the other form shown in these drawings is basically the same as the above-described hybrid integrated circuit device 10A, the following description focuses on the differences.

  In the hybrid integrated circuit device 10C shown in FIG. 2A, a substrate made of metal is used as the mounting substrate 28 on which the power element 22 is mounted. As described above, by using a metal having higher thermal conductivity than ceramic as the material of the mounting substrate 28, the heat released from the power element 22 can be released to the outside more efficiently. In this case, the lower electrode of the power element 22 is connected to the mounting board 28 via solder, and the conductive pattern 16 on the circuit board 12 and the power element 22 are connected to the mounting board 28 via the fine metal wires 20. And may be connected.

  In the hybrid integrated circuit device 10D shown in FIG. 2B, a metal substrate 34 made of a metal material such as aluminum or copper is fixed to the lower surface of a mounting substrate 28 made of ceramic. The lower surface of the metal substrate 34 is exposed to the outside from the sealing resin 30. Therefore, the heat generated from the power element 22 is discharged to the outside after passing through the wiring pattern 32, the mounting substrate 28, and the metal substrate 34 in this order.

  Here, the size of the metal substrate 34 in plan view is preferably larger than that of the power element 22, and the thickness may be the same as that of the mounting substrate 28. By doing so, the heat generated from the power element 22 and conducted through the mounting substrate 28 is diffused by the metal substrate 34. That is, the metal substrate 34 acts as a heat spreader, heat is released to the outside in a larger area than the power element 22, and heat dissipation characteristics are improved.

  In the hybrid integrated circuit device 10E shown in FIG. 2C, a metal substrate 34 is placed on the upper surface of a mounting substrate 28 made of ceramic, and the power element 22 is mounted on the upper surface of the metal substrate 34. Therefore, the heat generated from the power element 22 is released to the outside through the metal substrate 34, the wiring pattern 32, and the mounting substrate 28. As in the case of FIG. 2B, heat generated from the power element 22 is diffused to the periphery by the metal substrate 34, and a large area is conducted, so that heat dissipation is improved.

  In the hybrid integrated circuit device 10 </ b> F shown in FIG. 2D, the circuit board 12 is recessed in the thickness direction around the opening 18 to form a concave part 36, and the mounting board 28 is accommodated in the concave part 36. . Here, the depth of the concave portion 36 may be such that the mounting substrate 28 is completely accommodated in the thickness direction or may be partially accommodated. By doing in this way, the increase in the thickness of the whole apparatus by providing the mounting board | substrate 28 is suppressed. The matter of providing the concave portion 36 is applicable to the other forms described above.

  With reference to FIG. 3, the experimental results of measuring the thermal resistance of the hybrid integrated circuit device having the above-described configuration will be described. Here, the hybrid integrated circuit devices 10A, 10D, and 10E described above were prepared, and the temporal change of the thermal resistance was measured together with the conventional example. In the graph shown in this figure, the vertical axis represents thermal resistance, and the horizontal axis represents elapsed time in logarithm. Here, a low thermal resistance indicates that the heat dissipation is excellent. In addition, the thermal resistance in a region where the value of thermal resistance changes with time (region up to 10 seconds in the graph) is referred to as transient thermal resistance, and the thermal resistance in which the thermal resistance does not change over time thereafter (in the graph, The region after 10 seconds) is called steady thermal resistance.

  The hybrid integrated circuit device 10A shown in FIG. 1A is inferior in transient thermal resistance up to 10 seconds, but has a good value in steady thermal resistance thereafter. The reason why the transient heat capacity is inferior to that of the conventional example is that the mounting substrate 28 made of ceramic has a smaller heat capacity than the substrate 101 made of aluminum of the conventional example. Further, the reason why the hybrid integrated circuit device 10A is excellent in steady thermal resistance is that, as described above, a resin material having low thermal conductivity is not present in the heat path.

  When the experimental result of the hybrid integrated circuit device 10D shown in FIG. 2B is compared with the conventional example, the transient thermal resistance is inferior to the conventional example, but the steady thermal resistance is superior to the conventional example. The reason is the same as in the case of the hybrid integrated circuit device 10A. Further, when this result is compared with the hybrid integrated circuit device 10A, this case is superior in the transient thermal resistance value. This is because the metal substrate 34 disposed on the lower surface of the mounting substrate 28 functions as a heat sink, and the rapid temperature rise of the power element 22 is suppressed.

  Comparing the experimental result of the hybrid integrated circuit device 10E shown in FIG. 2C with the conventional example, the hybrid integrated circuit device 10E is superior to the conventional example in both transient thermal resistance and steady thermal resistance. The reason why the transient thermal resistance is excellent is that, in the initial stage of operation, the heat generated from the power element 22 is absorbed by the metal substrate 34 and a rapid temperature rise is suppressed. The reason why the steady thermal resistance is excellent is that the heat generated from the power element 22 is spread in all directions by the metal substrate 34 and then released to the outside from the mounting substrate 28 in a wide area.

  From the above experimental results, it can be said that the hybrid integrated circuit device of this embodiment is superior in heat dissipation than the conventional one.

10A, 10B, 10C, 10D, 10E, 10F Hybrid integrated circuit device 12 Circuit board 14 Lead 16 Conductive pattern 18 Opening 20 Metal fine wire 22 Power element 23 Control element 24 Chip element 28 Mounting substrate 30 Sealing resin 32 Wiring pattern 34 Metal Substrate 36 concave portion

Claims (11)

A circuit board having a conductive pattern disposed on the upper surface;
An opening partly opening the circuit board;
A mounting board disposed below the circuit board so as to overlap the opening,
A semiconductor element disposed on the upper surface of the mounting substrate and electrically connected to the conductive pattern;
A circuit device comprising:   The circuit device according to claim 1, wherein the mounting board is made of a material having thermal conductivity superior to that of the circuit board.   The circuit device according to claim 1, wherein the mounting substrate is a substrate made of ceramic. A metal substrate made of metal is disposed on the upper surface of the mounting substrate,
The circuit device according to claim 3, wherein the semiconductor element is fixed to the metal substrate. A wiring pattern is formed on the upper surface of the mounting substrate,
The electrode provided on the lower surface of the semiconductor element is connected to the conductive pattern disposed on the upper surface of the circuit board via the wiring pattern. Circuit device.   6. The circuit device according to claim 3, wherein a metal substrate is fixed to a lower surface of the mounting substrate.   The circuit device according to claim 6, wherein the metal substrate is exposed to the outside from a sealing resin that seals the circuit substrate.   The circuit device according to claim 1, wherein the mounting substrate is a substrate made of metal.   The circuit device according to claim 8, wherein the electrode provided on the lower surface of the semiconductor element is connected to the conductive pattern provided on the upper surface of the circuit board via the mounting substrate. A sealing resin that covers a part of the upper surface, side surface, and lower surface of the circuit board;
The circuit device according to claim 1, wherein a lower surface of the mounting substrate is exposed to the outside from the sealing resin.   The circuit device according to claim 1, wherein the circuit board is a board made of a resin material.

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