JP2014220319A - Mounting structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure of compact constitution in which a semiconductor device can be fixed and arranged stably between a board and a heat sink.SOLUTION: Since a MOSFET 4 can be pressed for a heat sink 3 from directly above by means of an elastic member 6, by arranging the elastic member 6 between the MOSFET 4 and a board 2, the MOSFET 4 can be fixed and arranged stably between the board 2 and the heat sink 3, a distance of which is fixed by a fixing member 5, by the elastic force of the elastic member 6, and a mounting structure can be made compact.

Description

  The present invention relates to a mounting structure in which a semiconductor device arranged on a heat sink so as to be able to conduct heat is fixedly arranged between a substrate and a heat sink and mounted on the substrate.

  2. Description of the Related Art Conventionally, a semiconductor device 500 configured as a package in which a semiconductor chip 500a that generates heat, such as a power MOSFET, is molded with a resin is mounted on a substrate (not shown), for example, as shown in FIG. 1). That is, the semiconductor device 500 is fixedly disposed on one surface of the heat sink 501 made of a material having excellent thermal conductivity such as copper, aluminum, or iron, using the screws 502. Further, the lead terminal 503 led out from the semiconductor device 500 is inserted into a through hole of a substrate disposed above the semiconductor device 500 and connected by solder.

  Between the semiconductor device 500 and the heat sink 501, an interposed member 504 such as grease or sheet material having excellent thermal conductivity is disposed. Therefore, the heat generated from the semiconductor chip 500a is radiated from the heat sink 501 to the outside through the interposed member 504. FIG. 3 shows a conventional mounting structure.

  By the way, in the mounting structure of FIG. 3, the position where the semiconductor device 500 is fixed to the heat sink 501 by the screw 502 is shifted from the position where the semiconductor device 500 is pressed against the heat sink 501 from directly above. There is. That is, when the screw 502 is tightened, the semiconductor device 500 may float from the heat sink 501 and the heat dissipation efficiency by the heat sink 501 may be reduced. Further, the position of the semiconductor device 500 may be displaced due to the loosening of the screw 501. In addition, the screw is loosened during the heat cycle, the thermal resistance between the semiconductor device and the heat sink is increased, heat dissipation is deteriorated, and the internal temperature of the semiconductor device 500 may exceed the heat resistance temperature and the semiconductor device 500 may be damaged. .

  Therefore, in Patent Document 1, mounting in which the semiconductor device 500 is fixedly disposed on the heat sink 501 by pressing the semiconductor device 500 from directly above the heat sink 501 by the elastic force of a plate-like spring member without using the screw 502. A structure has been proposed.

JP 2001-332670 A (paragraphs 0002 to 0007, 0020 to 0023, FIGS. 1, 3 and the like)

  However, when the semiconductor device 500 is fixedly disposed on the heat sink 501 by the spring member, it is necessary to form a structure for supporting the spring member in the heat sink 501, which causes a problem that the heat sink 501 is enlarged.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a mounting structure having a compact configuration in which a semiconductor device can be stably fixed and disposed between a substrate and a heat sink. .

  In order to achieve the above-described object, the mounting structure of the present invention is a mounting structure in which a semiconductor device arranged so as to be able to transfer heat to a heat sink is fixedly arranged between a substrate and the heat sink and mounted on the substrate. A surface on which the semiconductor device is disposed is disposed in a compressed state between the substrate and the semiconductor device, and a fixing portion that fixes the heat sink and the substrate disposed opposite to the substrate at a predetermined interval. And an elastic member for pressing and fixing the semiconductor device to the heat sink side by its elastic force.

  In the invention configured as described above, the heat sink and the substrate in which the surface on which the semiconductor device is disposed so as to be capable of transferring heat are opposed to the substrate are fixed at a predetermined interval by the fixing portion. Further, the elastic member is arranged between the semiconductor device and the substrate arranged between the heat sink and the substrate fixedly arranged at a predetermined interval by the fixing unit, and the semiconductor is formed by the elastic force of the elastic member. The device is pressed and fixed to the heat sink side.

  Therefore, compared to a conventional mounting structure using screws, there is no risk of the semiconductor device floating from the heat sink due to screw tightening or the position of the semiconductor device being displaced due to screw loosening. Since it can be pressed from directly above by the elastic member, the semiconductor device can be stably fixed and arranged between the substrate and the heat sink by the elastic force of the elastic member. Therefore, it is possible to suppress an increase in the thermal resistance between the semiconductor device and the heat sink, so that a heat dissipation structure with good heat dissipation characteristics can be realized.

  Further, as compared with a conventional mounting structure using a spring member, it is not necessary to form a structure for supporting the spring member on the heat sink, and the semiconductor device is fixed only by arranging an elastic member between the semiconductor device and the substrate. Therefore, the mounting structure can be made compact. Therefore, the semiconductor device can be stably fixed and disposed between the substrate and the heat sink, and a mounting structure having a compact configuration can be provided.

  The elastic member may be disposed over the entire surface of the semiconductor device facing the substrate.

  In this way, since the entire surface of the semiconductor device facing the substrate can be pressed against the heat sink by the elastic force of the elastic member, the semiconductor device can be securely mounted while realizing a good heat dissipation structure. Can be fixed against. In this case, by making the size of the elastic member substantially the same as the planar view shape of the semiconductor device, it is possible to suppress an increase in size of the mounting structure while maintaining a good heat dissipation structure.

  An elastic heat dissipation sheet may be disposed between the semiconductor device and the heat sink.

  If comprised in this way, a semiconductor device can be pinched | interposed and fixed reliably by the elastic member arrange | positioned at the board | substrate side, and the thermal radiation sheet | seat which has the elasticity arrange | positioned at the heat sink side. Therefore, it is possible to more stably fix the semiconductor device between the substrate and the heat sink while ensuring heat dissipation from the heat sink of the semiconductor device by the heat dissipation sheet.

  The elastic member may be formed of a heat dissipation material.

  In this way, in addition to heat radiation by the heat sink, heat can be radiated from the substrate side by the elastic member formed of the heat radiating material, so that the junction temperature of the semiconductor device can be further reduced and the life of the semiconductor device is improved. be able to. In this case, by disposing the elastic member formed of the heat dissipation material over the entire surface facing the substrate of the semiconductor device, a heat dissipation structure having even better heat dissipation characteristics can be realized.

  The elastic member may be formed of a heat insulating material.

  If comprised in this way, since it can suppress that a board | substrate is heated by the radiant heat of a semiconductor device with the elastic member formed with the heat insulation material, the radiant heat of a semiconductor device has an influence on other components etc. which were mounted in the board | substrate. Can be suppressed, and the reliability of a power supply module provided with a substrate can be improved.

  Moreover, it is preferable that the elastic member has adhesiveness.

  In this way, since the elastic member can be attached to the substrate or the semiconductor device, the mounting structure can be easily assembled by attaching the elastic member to the substrate or the semiconductor device at the time of assembly.

  Further, a lead terminal that is led out from the side surface of the semiconductor device and bent in a direction toward the substrate may be inserted into a through hole of the substrate and connected by solder.

  By the way, in the conventional mounting structure shown in FIG. 3, the semiconductor device 500 and the substrate are merely fixed by soldering the lead terminals 503 inserted through the through holes of the substrate. Therefore, a large thermal stress is generated in the soldered connection portion between the lead terminal 503 and the substrate, which may cause defects such as cracks in the solder, and there is a problem that the connection reliability between the semiconductor device 500 and the substrate is low. .

  However, when the lead terminal is inserted into the through hole of the board and connected by solder, according to the present invention, the thermal stress generated in the connecting portion between the lead terminal and the board by the solder is relieved by the elastic member. The connection reliability between the semiconductor device and the substrate can be improved.

  In the mounting structure of FIG. 3, after the semiconductor device 500 is first fixed to the heat sink 501 with screws 502, the lead terminals 503 of the semiconductor device 500 are inserted through the through-holes of the substrate and fixed with solder. Therefore, since it takes time to insert the lead terminal 503 into the through hole of the substrate in a state where the heat sink 501 is attached to the semiconductor device 500, there is a problem that the manufacturing cost increases.

  In the conventional mounting structure in which the semiconductor device 500 is fixed to the heat sink 501 by a spring member, the semiconductor device is supported by the spring member supported by the heat sink 501 in a state where the lead terminals 503 of the semiconductor device 500 are inserted into the through holes of the substrate. Since it is necessary to fix 500, there is a problem that it is difficult to assemble particularly when a plurality of semiconductor devices 500 are arranged adjacent to each other.

  However, when the lead terminal is inserted into the through hole of the substrate and connected by solder, according to the present invention, the lead is inserted into the through hole of the substrate with an elastic member interposed between the substrate and the semiconductor device. After the terminals are inserted, the semiconductor device can be fixed simply by sandwiching the semiconductor device between the substrate and the substrate with a heat sink and fixing the substrate and the heat sink with a predetermined interval at the fixing portion. Therefore, assembly is easy, and the number of manufacturing steps and manufacturing costs can be reduced.

  In addition, the substrate includes a relay substrate mounted upright on a surface facing the heat sink, and lead terminals led out from the side surface of the semiconductor device are inserted into through holes of the relay substrate and connected by solder. May be.

  Even if comprised in this way, the mounting structure of the practical structure which can show | play the effect similar to an above-described effect can be provided.

  According to the present invention, the fact that the substrate and the heat sink are fixed at a predetermined interval by the fixing portion can be used to press the semiconductor device against the heat sink from directly above with the elastic member. In addition, the semiconductor device can be stably fixed and arranged by the elastic force of the elastic member. Further, since the semiconductor device can be fixed only by disposing the elastic member between the semiconductor device and the substrate, the mounting structure can be made compact. Therefore, the semiconductor device can be stably fixed and disposed between the substrate and the heat sink, and a mounting structure having a compact configuration can be provided.

It is a figure which shows a power supply module provided with the mounting structure concerning one Embodiment of this invention. It is a figure which shows a power supply module provided with the mounting structure concerning other embodiment of this invention. It is a figure which shows the conventional mounting structure.

<One Embodiment>
An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing a power supply module having a mounting structure according to an embodiment of the present invention.

  As shown in FIG. 1, the power supply module 1 is excellent in thermal conductivity of copper, aluminum, iron or the like, and a substrate 2 constituted by a general substrate such as a composite substrate such as a printed circuit board, a resin substrate, or an alumina substrate. And a heat MOSFET 3 (field effect transistor) (corresponding to the “semiconductor device” of the present invention) disposed so as to be able to transfer heat to the heat sink 3. The MOSFET 4 is fixedly disposed between the substrate 2 and the heat sink 3. The MOSFET 4 is formed by packaging a semiconductor element (semiconductor chip) forming a field effect transistor with a resin.

  Further, the heat sink 3 is disposed so that the surface on which the MOSFET 4 is disposed is opposed to the substrate 2, and the substrate 2 and the heat sink 3 are fixed at a predetermined interval by a fixing portion 5. The fixing unit 5 includes a columnar body 5 a such as a hexagonal column formed of metal, and a screw 5 b that fixes the columnar body 5 a to the substrate 2 and the heat sink 3. The columnar body 5a is disposed between the substrate 2 and the heat sink 3, and the distance between the substrate 2 and the heat sink 3 is determined by the length of the columnar body 5a. Further, the screws 5b penetrating the substrate 2 and the heat sink 3 are screwed into the screw holes 5c formed in the axial direction on both end faces of the columnar body 5a, so that the columnar body 5a is connected to the substrate 2, the heat sink 3 and the heat sink 3. It is fixedly arranged between.

  The columnar body 5a may be fixedly disposed between the substrate 2 and the heat sink 3 by welding, for example, instead of the screw 5b. Moreover, the structure of the fixing | fixed part 5 is not limited to an above-described structure, The fixing | fixed part 5 may be comprised as long as the board | substrate 2 and the heat sink 3 can be fixed at predetermined intervals. .

  An elastic member 6 is disposed between the substrate 2 and the MOSFET 4 over the entire surface of the MOSFET 4 facing the substrate 2. Since the substrate 2 and the heat sink 3 are fixed by the fixing portion 5 at a predetermined interval, the elastic member 6 is disposed in a compressed state between the substrate 2 and the MOSFET 4. Therefore, the MOSFET 4 is pressed and fixed to the heat sink 3 side by the elastic force of the elastic member 6. As shown in FIG. 1, in this embodiment, a step is formed on the surface of the MOSFET 4 facing the substrate 2, and the surface of the elastic member 6 facing the MOSFET 4 can be engaged with the step of the MOSFET 4. Are provided with a step having the same shape. However, the step shape of the elastic member 6 is not essential, and the elastic member 6 without a step can be used. That is, since the elastic member 6 is an elastic body and can be used by crushing the elastic member 6, even if the elastic member 6 is not provided with a step, it is elastic along the step of the MOSFET 4 by crushing the elastic member 6. It is also possible to arrange the member 6. In other words, the elastic member 6 can be engaged with the step of the MOSFET 4 by crushing the elastic member 6 using the elastic force of the elastic member 6.

  Note that the thickness of the elastic member 6 is determined so that the elastic member 6 is disposed between the substrate 2 and the MOSFET 4 in a compressed state within a range not exceeding the elastic limit, and the distance between the substrate 2 and the heat sink 4 is determined. It is determined by the fixing part 5.

  Further, when the elastic member 6 is formed of a heat radiation material such as silicon rubber or rubber containing graphite, the following effects can be obtained.

  That is, in addition to the heat radiation of the MOSFET 4 by the heat sink 3, the elastic member 6 made of a heat radiation material can also radiate heat from the substrate 2 side, so that the junction temperature of the MOSFET 4 can be further reduced and the life of the MOSFET 4 is improved. be able to. In this case, by disposing the elastic member 6 formed of a heat dissipation material over the entire surface of the MOSFET 4 facing the substrate 2, a heat dissipation structure having good heat dissipation characteristics can be realized.

  Further, when the elastic member 6 is formed of a resin material having heat insulation properties such as polystyrene, polyethylene, and urethane, the following effects can be obtained.

  That is, since the substrate 2 is heated by the radiant heat of the MOSFET 4 by the elastic member 6 formed of a heat insulating material, the radiant heat of the MOSFET 4 affects other components and the like mounted on the substrate 2. And the reliability of the power supply module 1 including the substrate 2 can be improved.

  Further, when the elastic member has adhesiveness, the following effects can be obtained.

  That is, since the elastic member 6 can be affixed to the substrate 2 or the MOSFET 4, the power supply module 1 can be easily assembled by affixing the elastic member 6 to the substrate 2 or the MOSFET 4 during assembly.

  An insulating heat dissipation sheet 7 having elasticity is disposed between the MOSFET 4 and the heat sink 3. The MOSFET 4 is disposed so as to be able to transfer heat to the heat sink 3 via the heat dissipation sheet 7. The heat dissipation sheet 7 is made of a heat dissipation material such as silicon rubber or rubber containing graphite. Further, the MOSFET 4 and the metal heat sink 3 are insulated by the insulating heat radiation sheet 7.

  In the substrate 2, a through hole 8 having a conductor 8 a provided on the inner peripheral surface thereof is formed for connection to the MOSFET 4. A lead terminal 4 a led out from the side surface of the MOSFET 4 and bent in a direction toward the substrate 2 is inserted into the through hole 8 of the substrate 2 and connected by solder H.

  As described above, in this embodiment, the heat sink 3 and the substrate 2 on which the surface on which the MOSFET 4 is disposed so as to be capable of transferring heat are opposed to the substrate 2 are fixed by the fixing portion 5 at a predetermined interval. Further, the elastic member 6 is arranged in a compressed state between the MOSFET 4 and the substrate 2 arranged between the heat sink 3 and the substrate 2 fixedly arranged at a predetermined interval by the fixing unit 5. Due to the elastic force, the MOSFET 4 is pressed and fixed to the heat sink 3 side.

  Therefore, as compared with the mounting structure using the conventional screw shown in FIG. 3, the heat generated by the MOSFET 4 floating from the heat sink 3 due to the screw tightening, the positional shift of the MOSFET 4 due to the screw loosening, and the screw loosening during the heat cycle. The MOSFET 4 can be pressed against the heat sink 3 from directly above the heat sink 3 by the elastic member 6 without increasing the resistance, deteriorating heat dissipation, or even exceeding the heat resistance temperature. Therefore, the MOSFET 4 can be stably fixedly disposed with the elastic force of the elastic member 6. Therefore, it is possible to prevent the MOSFET 4 from floating from the heat sink 3 and to suppress an increase in the thermal resistance between the MOSFET 4 and the heat sink 3, so that a heat dissipation structure with good heat dissipation characteristics can be realized.

  Further, as compared with a conventional mounting structure using a spring member, it is not necessary to form a structure for supporting the spring member in the heat sink 3, and the MOSFET 4 can be fixed only by disposing the elastic member 6 between the MOSFET 4 and the substrate 2. Therefore, the mounting structure can be made compact. Therefore, the MOSFET 4 can be stably fixed and disposed between the substrate 2 and the heat sink 3, and the power supply module 1 having a compact mounting structure can be provided.

  Further, since the elastic member 6 is disposed over the entire surface of the MOSFET 4 facing the substrate 2, the elastic member 6 is elastically applied to the heat sink 3 over the entire surface of the MOSFET 4 facing the substrate 2. Can be pressed. Therefore, the MOSFET 4 can be reliably fixed to the heat sink 3 while realizing a good heat dissipation structure. In this case, by making the size of the elastic member 6 substantially the same as the planar view shape of the MOSFET 4, it is possible to suppress an increase in size of the mounting structure while maintaining a good heat dissipation structure.

  Further, since the heat radiation sheet 7 having elasticity is disposed between the MOSFET 4 and the heat sink 3, the elastic member 6 disposed on the substrate 2 side and the heat radiation sheet 7 having elasticity disposed on the heat sink 3 side are used. The MOSFET 4 can be clamped and fixed securely. Therefore, the heat dissipation from the heat sink 3 of the MOSFET 4 can be secured by the heat dissipation sheet 7 and the MOSFET 4 can be fixedly disposed between the substrate 2 and the heat sink 3 more stably.

  A lead terminal 4a that is led out from the side surface of the MOSFET 4 and bent in the direction toward the substrate 2 is inserted into the through hole 8 of the substrate 2 and connected by the solder H. The lead terminal 4a by the solder H and the substrate 2 are connected to each other. Since the thermal stress generated in the connection portion is relaxed by the elastic member 6, the connection reliability between the MOSFET 4 and the substrate 2 can be improved.

  Further, for example, by attaching the elastic member 6 to the substrate 2 or the MOSFET 4, the lead terminal 4 a is inserted into the through hole 8 of the substrate 2 with the elastic member 6 interposed between the substrate 2 and the MOSFET 4, and then the heat sink The MOSFET 4 can be fixed simply by sandwiching the MOSFET 4 between the substrate 2 and the substrate 2 and fixing the substrate 2 and the heat sink 3 with a fixing portion 5 at a fixed interval. Therefore, the power supply module 1 can be easily assembled, and the number of manufacturing steps and manufacturing costs can be reduced.

<Other embodiments>
Another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a view showing a power supply module having a mounting structure according to another embodiment of the present invention. This embodiment is different from the above-described embodiment in that the substrate 2 includes a relay substrate 10 mounted on the surface facing the heat sink 3. A connector 9 is provided on the substrate 2, and the relay substrate 10 is mounted on the surface of the substrate 2 facing the heat sink 3 by being inserted into the connector 9.

  Further, a through hole 11 having a conductor 11 a provided on the inner peripheral surface thereof is formed in the relay substrate 10 for connection to the MOSFET 4. The lead terminal 4 a led out from the side surface of the MOSFET 4 is inserted into the through hole 11 of the relay substrate 10 and connected by the solder H. Since the other configuration is the same as that of the above-described embodiment, the description of the configuration is omitted by attaching the same reference numerals.

  Also in this embodiment, the same effect as the above-described embodiment can be obtained, and the power supply module 1 including a mounting structure with a practical configuration can be provided.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the semiconductor device of the present invention is configured. The semiconductor element to be performed is not limited to the above example, but a three-terminal regulator, a rectifier diode, an insulated gate bipolar transistor (IGBT), a thyristor, a gate turn-off thyristor (semiconductor element such as a power MOSFET or a bipolar transistor packaged with resin) The semiconductor device may be formed of a so-called power semiconductor element that generates heat, such as GTO) or triac.

  Further, the shape of the semiconductor device (MOSFET 4) is not limited to the above-described example, and the step may not be formed on the surface facing the substrate. Further, the elastic member only needs to be disposed between the substrate and the semiconductor device so that at least a portion in which the semiconductor element forming the semiconductor device is incorporated can be pressed. What is necessary is just to comprise so that a part can be pressed.

  The semiconductor device may be disposed in direct contact with the heat sink. However, as described above, it is desirable that the heat sink and the semiconductor device are insulated by interposing an insulating heat dissipation sheet or the like therebetween.

  The shape of the heat sink is not limited to the above example, and the surface opposite to the side where the semiconductor device is disposed of the heat sink may be formed in a sword mountain shape or a bellows shape in which plate-like or rod-like fins are formed. Good. If it does in this way, the heat dissipation effect by a heat sink can further be improved.

  The present invention can be widely applied to a mounting structure in which a semiconductor device arranged to be able to transfer heat to a heat sink is fixedly arranged between the substrate and the heat sink and mounted on the substrate.

2 Substrate 3 Heat sink 4 MOSFET (semiconductor device)
4a Lead terminal 5 Fixing part 6 Elastic member 7 Heat radiation sheet 8, 11 Through hole 10 Relay board H Solder

Claims (8)

In a mounting structure in which a semiconductor device arranged to be able to transfer heat to a heat sink is fixedly arranged between a substrate and the heat sink and mounted on the substrate,
A fixing portion that fixes the heat sink and the substrate, the surface on which the semiconductor device is disposed, facing the substrate, with a predetermined interval therebetween;
A mounting structure comprising: an elastic member that is arranged in a compressed state between the substrate and the semiconductor device, and that presses and fixes the semiconductor device to the heat sink side by its elastic force.   The mounting structure according to claim 1, wherein the elastic member is disposed over the entire surface of the semiconductor device facing the substrate.   The mounting structure according to claim 1, wherein a heat dissipation sheet having elasticity is disposed between the semiconductor device and the heat sink.   The mounting structure according to claim 1, wherein the elastic member is made of a heat dissipation material.   The mounting structure according to claim 1, wherein the elastic member is formed of a heat insulating material.   The mounting structure according to claim 1, wherein the elastic member has adhesiveness.   The lead terminal led out from the side surface of the semiconductor device and bent in a direction toward the substrate is inserted into a through hole of the substrate and connected by solder. Mounting structure. The board comprises a relay board mounted upright on the surface facing the heat sink,
7. The mounting structure according to claim 1, wherein a lead terminal led out from a side surface of the semiconductor device is inserted into a through hole of the relay substrate and connected by solder.

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