JP2011199213A - Power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power module increasing production efficiency while suppressing warpage of a substrate.SOLUTION: The module includes a plate-shaped substrate 11 having one surface and the other surface, a plurality of electronic components 12 mounted onto one surface of the substrate 11, a radiator 13 disposed on the other surface of the substrate 11 to be in thermal contact with the electronic components 12, and a pressing member 14 attached to the substrate 11 in face with the electronic components 12 and pressing one surface of the substrate 11. The pressing member 14 has a facing part 141 facing one surface of the substrate 11, a fixed part 142 joined with a peripheral edge part of the facing part 141 at one end and fixed to one surface of the substrate 11 at the other end, and a pressing part 143 joined with the facing part 141 at one end and pressing one surface of the substrate 11 at the other end. Since the warpage of the substrate 11 is suppressed to increase adhesiveness between the substrate 11 and the radiator 13, heat resistance of the power module 10 is reduced.

Description

  The present invention relates to a power module in which an electronic component such as a semiconductor element is mounted on a substrate.

  Conventionally, a power module in which an electronic component such as a semiconductor element is mounted on a substrate such as a resin is known. Such a power module is used, for example, in power equipment such as an air conditioner, and performs power conversion and control. An electronic component such as a semiconductor element is also called a heating element, and generates heat by the operation of the semiconductor element. For this reason, a heat radiator such as a heat sink or a refrigerant jacket is attached to the substrate to radiate heat.

  In the power module as described above, warpage of the substrate that occurs when the radiator is attached to the substrate becomes a problem. The warp of the substrate reduces the adhesion between the substrate and the radiator and reduces the heat dissipation. Techniques for solving the reduction in heat dissipation of the power module due to substrate warping are disclosed in the following patent documents.

  For example, as in Patent Document 1, it is possible to suppress warping of the substrate by providing a resin sealing frame when resin-sealing a bare chip of a semiconductor element. However, when a plurality of bare chips are mounted on the substrate, if a resin sealing frame is provided for each bare chip, the number of bare chips increases and the mounting operation of the resin sealing frame becomes complicated, resulting in poor production efficiency. . Although a method of sealing all of the plurality of bare chips using a single resin sealing frame is also conceivable, the amount of resin required for sealing increases, and the cost increases accordingly.

  Further, as in Patent Document 2, the thermal resistance can be reduced by providing a heat conductive member such as a metal foil or heat conductive grease in the gap between the heat sink and the heat sink formed by warping of the substrate. . However, since the number of assembling steps such as positioning of the heat conducting member increases, the production efficiency is not good. The cost for adding the heat conducting member increases.

  Warpage of the substrate can also be suppressed by increasing the number of places where the radiator is fixed to the substrate with screws or the like. However, since the number of mounting steps increases, production efficiency decreases. Moreover, since the screw holes formed in the substrate also increase, the wiring patterns that can be formed in the substrate are limited.

JP 2008-53588 A JP 2003-86745 A

  An object of the present invention is to provide a power module in which production efficiency is improved while suppressing warping of a substrate.

  The power module of the present invention includes a plate-like substrate having one surface and another surface, a plurality of electronic components mounted on one surface of the substrate, a radiator provided on the other surface of the substrate and in thermal contact with the electronic components, And a pressing member that is attached to the substrate to face the electronic component and presses one surface of the substrate.

  In the power module of the present invention, the pressing member has a facing portion that faces one surface of the substrate, a fixed portion that has one end joined to the peripheral portion of the facing portion, and the other end fixed to the one surface of the substrate, and one end facing the facing portion. And a pressing portion that presses one surface of the substrate at the other end.

  In the power module of the present invention, the pressing portion presses between adjacent electronic components on one surface of the substrate.

  In the power module of the present invention, the facing portion is a plate or a plate provided with an opening.

  In the power module of the present invention, the radiator, the substrate, and the pressing member are integrated by the same fixing means.

  In the power module of the present invention, the pressing member is made of resin.

  According to the power module of the present invention, since the pressing member presses one surface of the substrate toward the radiator, the warpage of the substrate can be suppressed. Thereby, since the adhesiveness of a board | substrate and a heat radiator improves, the thermal resistance of a power module can be reduced.

  According to the power module of the present invention, the pressing member is composed of a single member having a fixing portion and a pressing portion each having one end connected to the opposing portion, so that pressing while suppressing warping of the substrate. It is possible to reduce the man-hours for attaching the members. That is, when the pressing member is fixed to the substrate, the pressing portion presses between the plurality of electronic components mounted on the substrate, so that the warpage of the substrate can be suppressed. On the other hand, if the fixing portion is fixed to the substrate, the pressing member can be fixed, so that the number of fixing points can be minimized. Thereby, the man-hour for attaching the pressing member is reduced, and the production efficiency of the power module can be improved.

  According to the power module of the present invention, since the pressing portion presses between adjacent electronic components on one surface of the substrate, the warpage of the substrate can be effectively suppressed. Since the portion where the electronic component is mounted has higher rigidity, the portion where the electronic component is not mounted is more susceptible to the force of warping the substrate. Since the pressing portion presses a portion that is easily affected by the force that warps the substrate, the force that warps the substrate is effectively weakened. It is also effective against warping of the substrate that occurs later due to the heat of the electronic component.

  According to the power module of the present invention, the opposing portion of the pressing member can be selectively formed on a plate body or a plate body provided with an opening, depending on the type of electronic component or radiator. For this reason, it is possible to prevent heat from spreading into the space inside the pressing member provided to cover the electronic component. In particular, when the electronic component includes a heat generating element such as a semiconductor element, the amount of heat generated is large, so that the temperature of the space inside the pressing member also increases. However, the electronic component can be prevented from being destroyed by the heat of the heat generating element.

  According to the power module of the present invention, the radiator, the substrate, and the pressing member can be connected and fixed to each other by the same fixing means, so that the number of mounting steps can be reduced. Thereby, the assembly man-hour of a power module is reduced and the production efficiency of a power module can be improved. In particular, when the fixing means is a screw, since the screw holes are common, the relative positioning of the radiator, the substrate, and the pressing member can be easily performed.

  According to the power module of the present invention, the pressing member can be formed of an inexpensive resin, so that the cost of the power module can be reduced. Moreover, even when the shape of the pressing member is complicated (for example, when a plurality of pressing portions are provided irregularly), it can be easily molded by any molding method, so the degree of freedom in the shape is high. Excellent mass productivity.

It is the sectional view along the (a) top view and (b) AA line which show the power module concerning a first embodiment. It is a front view which shows the power module which concerns on 1st embodiment. It is an exploded sectional view showing the power module concerning a first embodiment. (A) The top view which shows the power module which concerns on 2nd embodiment, (b) The top view which shows the modification of the power module which concerns on 2nd embodiment. It is sectional drawing along the (a) top view and (b) BB line which show the power module which concerns on 3rd embodiment. It is the (a) top view and (b) front view which show the power module which concerns on 4th embodiment. It is the (a) top view and (b) front view which show the modification of the power module which concerns on 4th embodiment. It is (a) top view and (b) front view which show the other modification of the power module which concerns on 4th embodiment.

  Hereinafter, embodiments of a power module according to the present invention will be described with reference to the drawings. In the present specification, each drawing is schematically shown, and when the same reference numeral is given, the same configuration is shown. In this specification, the one surface of the substrate refers to the surface on the side where electronic components and the like are provided, and the other surface of the substrate refers to the surface on the side where the radiator is provided.

  As shown in FIGS. 1 and 2, the power module 10 according to the first embodiment includes a plate-shaped substrate 11, a plurality of electronic components 12 mounted on one surface of the substrate 11, and an electronic component on the other surface of the substrate 11. A heat dissipator 13 provided so as to be in thermal contact with the electronic component 12 and a pressing member 14 attached to one surface of the substrate 11 so as to face the electronic component 12.

  The substrate 11 is an insulating plate. A wiring pattern is formed on the substrate 11. Specifically, the substrate 11 may be a resin substrate using an epoxy resin or a ceramic substrate using alumina or the like. More specifically, the substrate 11 is a glass epoxy resin substrate or the like. Although not shown, the substrate 11 is appropriately provided with known thermal vias. The heat of the electronic component 12 is conducted to the radiator 13 through this thermal via.

  The electronic component 12 is various components that constitute an electronic circuit for performing power conversion and control. The electronic component 12 is, for example, a semiconductor element (heating element) such as a transistor or a diode, and more specifically, an IGBT (Insulated Gate Bipolar Transistor), an FWD (Free Wheeling Diode), or the like. An integrated circuit such as LSI (Large Scale Integration) may be used. The electronic component 12 is mounted on one surface of the substrate 11 in a bare chip state and sealed with a resin or the like for protection. You may mount in the board | substrate 11 through a heat spreader for heat dissipation improvement. What was previously packaged with resin or the like can be mounted on one surface of the substrate 11. The electronic component 12 is appropriately arranged according to the wiring pattern formed on the substrate 11. The electronic component 12 is not limited to a semiconductor element. For example, a resistor, a capacitor, a coil, etc. are included.

  The radiator 13 is for radiating heat generated in the electronic component 12, and is provided on the other surface of the substrate 11. The radiator 13 is in thermal contact with the electronic component 12 through the substrate 11. Examples of the radiator 13 include a metal plate having high thermal conductivity, a heat sink, a refrigerant jacket, and the like, and these can be arbitrarily selected. An insulating layer (not shown) is provided between the radiator 13 and the substrate 11 to prevent a short circuit. The radiator 13 is attached to the substrate 11 by fixing means 15. The fixing means 15 is arbitrary, for example, a bolt and a nut.

  The pressing member 14 is for suppressing warpage of the substrate 11. The pressing member 14 is attached to face the electronic component 12 and presses one surface of the substrate 11 located between the adjacent electronic components 12 in the direction of the radiator 13. Similar to the radiator 13, the pressing member 14 is fixed to one surface of the substrate 11 by the fixing means 15. The pressing member 14 includes a facing portion 141, a fixing portion 142, and a pressing portion 143.

  The facing portion 141 of the pressing member 14 is a quadrangular plate. The facing portion 141 faces the one surface of the substrate 11 with a certain gap. The width of the gap formed between the facing portion 141 and the substrate 11 is larger than the thickness of the sealing resin that protects the electronic component 12. The facing portion 141 is disposed so as to cover the plurality of electronic components 12 mounted on one surface of the substrate 11. The shape of the facing portion 141 is not limited to a quadrangle, and may be another polygon, a circle, an ellipse, or the like.

  The fixing portion 142 of the pressing member 14 is a rectangular cylinder. One end of the fixing portion 142 is joined to the peripheral edge portion of the facing portion 141, and the other end is fixed to one surface of the substrate 11. The height from one end of the fixing portion 142 to the other end is equal to the width of the gap formed between the facing portion 141 and the substrate 11. A flange 142 a is provided at the other end of the fixed portion 142. The pressing member 14 is fixed so that the flange 142a contacts one surface of the substrate 11. Since the contact area with the substrate 11 increases, the pressing member 14 can be firmly fixed to one surface of the substrate 11. As shown in FIG. 2, an opening 144 is formed in a part of the fixing portion 142 (the wall surface portion of the rectangular cylindrical body). Thereby, it is possible to prevent heat from spreading into the space inside the pressing member 14. The shape of the fixing portion 142 is appropriately designed according to the shape of the facing portion 141.

  The pressing part 143 of the pressing member 14 is a rod. One end of the pressing portion 143 is joined to the facing portion 141, and the other end presses one surface of the substrate 11 toward the radiator 13. The shape of the pressing portion 143 is, for example, a polygonal column shape such as a quadrangular column or a cylindrical shape, but is not particularly limited. The height from one end of the pressing portion 143 to the other end is equal to the width of the gap formed between the facing portion 141 and the substrate 11 or is higher than the width of the gap. The arrangement of the pressing portion 143 is appropriately designed so that the other end is arranged between the adjacent electronic components 12.

  As the material of the pressing member 14, it is preferable to use a thermosetting resin or the like. It is excellent in cost and mass productivity, and deformation such as distortion due to thermal stress can be prevented. Specific examples of the thermosetting resin include epoxy resins, phenol resins, and synthetic resins thereof. The pressing member 14 is required to be a hard material. In this specification, “hard” means that there is no deformation with respect to the warp of the substrate 11.

  The pressing member 14 is molded by a molding method such as injection molding or cast molding, but is not particularly limited. Such a molding method has a high degree of freedom in shape and is excellent in mass productivity.

  As shown in FIG. 3, the power module 10 is integrated by connecting and fixing the radiator 13, the substrate 11, and the pressing member 14 in this order by the same fixing means 15. Mounting holes 15a, 15b, and 15c are formed in the fixing portion 142 of the substrate 11, the radiator 13, and the pressing member 14, respectively. The mounting holes 15 a, 15 b, 15 c are positioned at positions corresponding to each other, and constitute one mounting hole corresponding to the fixing means 15. The fixing means 15 is a bolt and nut (not shown). You may provide a screw thread in each attachment hole 15a, 15b, 15c.

  Next, the action of the pressing member 14 when the power module 10 is assembled will be described.

  When the radiator 13 is fixed to the substrate 11 by the fixing means 15, a force perpendicular to the one surface of the substrate 11 is applied around the attachment hole 15 a. However, it is difficult to fix all the fixing means 15 in a uniform direction with a uniform force, and a force applied in a direction parallel to one surface of the substrate 11 is also generated. This is a factor that causes the substrate 11 to warp.

  Since the portion where the electronic component 12 is mounted on the substrate 11 has higher rigidity, the portion where the electronic component 12 is not mounted is more susceptible to the force that causes the warpage of the substrate 11. Therefore, it is considered that the area between the adjacent electronic components 12 is easily affected by the force that causes the warpage of the substrate 11.

  When the fixing means 15 is attached to each fixing portion 142 in order, it is considered that the substrate 11 is temporarily warped. However, as the attaching operation of the fixing means 15 to the fixing portion 142 proceeds, the other end of the pressing portion 143 presses one surface of the substrate 11 positioned between the adjacent electronic components 12 in the direction of the radiator 13. When the attachment of the fixing means 15 to each fixing portion 142 is completed, the warpage of the substrate 11 that has temporarily occurred is suppressed by the pressing member 14, and the other surface of the substrate 11 and the radiator 13 are in close contact with each other. Become.

  Even when fixing means 15 are attached to each fixing portion 142 at the same time, it is difficult to fix all of them with a uniform force, so it is considered that a force that causes warping of substrate 11 is applied. However, since the pressing member 14 is a hard material, the force that causes the warpage of the substrate 11 is smaller than the force by which the pressing portion 143 presses one surface of the substrate 11. Accordingly, the warping of the substrate 11 is suppressed during the fixing work of the fixing means 15.

  On the other hand, a difference in the expansion coefficient between one surface and the other surface of the substrate 11 due to the heat of the electronic component 12 also causes the substrate 11 to warp. Such warpage of the substrate 11 due to the heat of the electronic component 12 is likely to occur later. However, in the pressing member 14, the pressing portion 143 effectively presses a portion that is easily affected by a force that causes warping of the substrate 11. Further, since the pressing member 14 is made of a hard material, the force that causes the warpage of the substrate 11 is smaller than the force by which the pressing portion 143 presses one surface of the substrate 11. Therefore, warping of the substrate 11 that occurs later can be suppressed.

  In addition, since the flange 142a is provided at the other end of the fixing portion 142, it is possible to prevent a force in the vertical direction from being applied locally to one surface of the substrate 11 and to prevent the substrate around the electronic component 12 from being applied. 11 can be pressed over a wide range. Thereby, the curvature of the board | substrate 11 is reduced.

  The pressing member 14 is disposed so that the facing portion 141 covers the plurality of electronic components 12, and the other end of the flange portion 142 a and the pressing portion 143 provided at the other end of the fixing portion 142 is in contact with one surface of the substrate 11. Yes. However, since the pressing member 14 is made of resin, it has an insulating property. Therefore, even if the wiring pattern is formed at the contact portion with one surface of the substrate 11, no short circuit occurs.

  Thus, by providing the pressing member 14 in the power module 10, the warpage of the substrate 11 in the attaching process of the fixing means 15 is suppressed, and in addition, there is a possibility that the power module 10 may be generated later by the operation of the power module 10. Warpage of a certain substrate 11 can also be suppressed.

  According to the power module 10 according to the present embodiment, the warping of the substrate 11 can be suppressed by providing the pressing member 14. Thereby, since the adhesiveness of the board | substrate 11 and the heat radiator 13 improves, the thermal resistance of the power module 10 can be reduced.

  According to the power module 10 according to the present embodiment, since the pressing portion 142 presses one surface of the substrate 11 when the pressing member 14 is fixed to the substrate 11, warping of the substrate 11 can be suppressed. On the other hand, if the fixing portion 142 is fixed to the substrate 11, the pressing member 14 can be fixed, so that the number of fixing points can be minimized. Thereby, the attachment man-hour of the pressing member 14 is reduced and the production efficiency of the power module 10 can be improved.

  According to the power module 10 according to the present embodiment, the pressing portion 143 presses between adjacent electronic components 12 on one surface of the substrate 11, so that the warpage of the substrate 11 can be effectively suppressed. That is, since the pressing portion 143 presses a portion that is easily affected by the force that generates the warp of the substrate 11, the effect of the force that generates the warp of the substrate 11 can be effectively weakened to suppress the warp of the substrate 11. . For this reason, it is also effective against the warp of the substrate 11 that occurs later due to the heat of the electronic component 12.

  According to the power module 10 according to the present embodiment, the radiator 13, the substrate 11, and the pressing member 14 can be connected and fixed to each other by the same fixing means 15, so that the number of mounting steps for each component can be reduced. Can be reduced. Thereby, the assembly man-hour of the power module 10 is reduced, and the production efficiency of the power module 10 can be improved. Since the mounting holes are common, the relative positioning of each of the radiator 13, the substrate 11, and the pressing member 14 can be easily performed.

  According to the power module 10 according to the present embodiment, since the pressing member 14 can be formed of an inexpensive resin, the pressing member 14 is excellent in mass productivity and the cost of the power module 10 can be reduced. .

  According to the power module 10 according to the present embodiment, the warp of the substrate 11 can be suppressed by minimizing the location where the fixing means 15 is fixed, and therefore the mounting holes formed in the substrate 11 are also suppressed to the minimum necessary. Can do. Further, since the pressing member 14 is formed of an insulating resin, no short circuit occurs even if a wiring pattern is formed at a location pressed by the pressing portion 143. Therefore, the wiring pattern can be formed in the same manner as before.

  The power module 10 according to the first embodiment of the present invention has been described above, but the power module according to the present invention can be implemented in other forms.

  For example, the opposing portion of the pressing member may be a plate provided with an opening. As in the power module 20 according to the second embodiment shown in FIG. 4A, a pressing member 24 in which an opening 244 is formed in the facing portion 241 may be used. When the electronic component 22 that generates less heat than the electronic component 12 is mounted on the substrate 11, a press having a plurality of slits 344 formed in the facing portion 341 as in the power module 30 shown in FIG. The member 34 can also be used. The opening 244 or the slit 344 is preferably formed at a position facing the electronic component 12 in terms of improving heat dissipation. The opening 244 or the slit 344 may be formed in place of the opening 144 formed in the fixing portion 142 of the pressing member 14 provided in the power module 10 described above, or may be formed in addition to the opening 144. Also good.

  According to the power modules 20 and 30 according to the second embodiment, the facing portions 241 and 341 of the pressing members 24 and 34 are appropriately selected according to the heat generation amount of the electronic components 12 and 22 and the type and performance of the radiator 13. Can be designed. For this reason, it can prevent effectively that the heat which generate | occur | produces in the electronic components 12 and 22 gets into the space inside the press members 24 and 34. FIG. Thereby, destruction by the heat | fever of the electronic components 12 and 22 mounted in the board | substrate 11 can be prevented effectively.

  As in the power module 40 according to the third embodiment illustrated in FIG. 5, a pressing member 44 including a plurality of pressing portions 443 in the facing portion 141 may be used. As the number of electronic components 32 mounted on the substrate 11 increases, the places that can be pressed on one surface of the substrate 11 are limited. However, since the pressing portion 443 is appropriately provided at a position that is easily affected by the force that generates the warp of the substrate 11, the warp of the substrate 11 can be effectively prevented.

  Even when the electronic components 32 are not neatly mounted on the substrate 11, if the pressing members 443 are appropriately arranged so as to press between the adjacent electronic components 32 and the pressing member 44 is formed, the substrate 11. Can be effectively prevented. Since the pressing member 44 can be formed of resin, even if the shape of the pressing member 44 is complicated, it can be easily molded by any molding method such as injection molding, so the degree of freedom in shape is high and mass productivity is excellent. ing.

  Like the power module 50 according to the fourth embodiment shown in FIG. 6, the fixed portion 542 whose one end is joined to a part of the peripheral portion of the facing portion 141 and the other end is fixed to one surface of the substrate 11 is opposed to You may use the press member 54 with which at least 1 was provided in each edge | side of the part 141. FIG. The fixing portion 542 may be a minimum necessary size to which the fixing means 15 is attached. Since the electronic component 32 is not sealed by the pressing member 54, it is not necessary to provide the opening portion 244 and the slit 344 in the facing portion 141, and the amount of material used for the pressing member 54 can be reduced. The degree of freedom related to the wiring pattern formed on the substrate 11 is also improved.

  Like the pressing member 64 provided in the power module 60 illustrated in FIG. 7, the fixing portion 542 may be provided at each corner portion of the facing portion 141. Further, as in the power module 70 shown in FIG. 8, a pressing member 74 in which the facing portion 741 is formed in a cross shape can be used. Even when the pressing members 64 and 74 are used, the same effect as that of the pressing member 54 described above can be obtained.

  The power module of the present invention is not limited to the above embodiment. For example, the material of the pressing member may be metal instead of resin. A metal pressing member is formed by processing a metal plate into a predetermined shape having a facing portion and a fixed portion by bending or deep drawing, and welding a metal bar-like member to a predetermined position of the facing portion. be able to. When a metal pressing member is used, it is attached to the substrate via an insulating means such as an insulating sheet. Thereby, it can prevent that a short circuit arises in contact with the wiring pattern formed in the board | substrate. Since the metal material has higher thermal conductivity than the resin material, the heat dissipation on one surface side of the substrate can be improved. You may improve the hardness of a press member by providing a metal plate etc. in the opposing part of a press member.

  Moreover, the opening part provided in the opposing part of a press member may be formed in mesh shape (fine lattice shape). Alternatively, the radiator, the substrate, and the fixing member may be fixed by the fixing means 15 from one surface side of the substrate 11.

  The degree of warpage of the board and the magnitude of the force that causes the board to warp are the size, thickness, and shape of the board 11, the number and position of mounting holes for mounting the fixing means, or the arrangement and number of electronic components, And the amount of heat generated. Therefore, the power module of the present invention may be implemented as a power module using a pressing member that is appropriately designed in combination with the techniques listed in the above embodiments in consideration of these various conditions.

  It should be noted that the present invention can be implemented in a mode in which various improvements, modifications, or variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Moreover, you may implement with the form which substituted any invention specific matter to the other technique within the range which the same effect | action or effect produces.

11: Substrate 12, 22, 32: Electronic component 13: Radiator 14, 24, 34, 44, 54, 64, 74: Pressing member 15: Fixing means 141, 241, 341, 741: Opposing portion 142, 542: Fixed Part 143, 443: Pressing part 144, 244: Opening part 344: Slit 10, 20, 30, 40, 50, 60, 70: Power module

Claims (6)

A plate-like substrate having one side and the other side;
A plurality of electronic components mounted on one surface of the substrate;
A radiator that is provided on the other surface of the substrate and is in thermal contact with the electronic component;
A pressing member attached to the substrate to face the electronic component and pressing one surface of the substrate;
A power module comprising: The pressing member is
A facing portion facing one surface of the substrate;
One end is joined to the peripheral edge of the facing portion, and the other end is fixed to one surface of the substrate;
One end is joined to the facing portion, and the other end is a pressing portion that presses one surface of the substrate,
The power module according to claim 1, comprising:   The power module according to claim 2, wherein the pressing portion presses between the adjacent electronic components on one surface of the substrate.   The power module according to claim 2, wherein the facing portion is a plate body or an opening portion provided in the plate body.   The power module according to any one of claims 1 to 4, wherein the radiator, the substrate, and the pressing member are integrated by the same fixing means.   The power module according to any one of claims 1 to 5, wherein the pressing member is formed of a resin.

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