JP2011187819A - Resin sealed power module and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin sealed power module easily improved in insulation characteristic without a harmful effect, and to provide a method of manufacturing the same. <P>SOLUTION: The resin sealed power module includes an insulating board, a power semiconductor element arranged on the insulating board, a plurality of hollow cylindrical sockets arranged on the insulating board, and a resin case in which a plurality of recesses are formed on its upper surface, and is so formed as to cover the power semiconductor element and the plurality of hollow cylindrical sockets. The plurality of hollow cylindrical sockets are exposed from the plurality of recesses in such manner as a single hollow cylindrical socket among the plurality of hollow cylindrical sockets is exposed from a single recess among the plurality of recesses. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resin-sealed power module in which a power semiconductor element or the like is resin-sealed using a transfer mold method, and a method for manufacturing the same.

  Patent Document 1 discloses a technique for sealing a QFN (Quad Flat Non-Leaded Package) type semiconductor package by a molding method. This technique relates to a process in which electrodes are exposed on the same surface of a casing by an injection molding method using a release sheet. Patent Document 2 discloses a configuration in which a cylindrical electrode extends on a surface opposite to a surface on which a heat sink is exposed. This relates to a process of once arranging a plurality of electrodes and then cutting the upper surface thereof.

JP 2004-253498 A JP 2001-223321 A Japanese Utility Model Publication No. 4-127996 JP 2002-124602 A Japanese Patent Laid-Open No. 10-321786

  The electrode used in the resin-encapsulated power module needs to be arranged with a sufficient creepage distance from the heat sink. Therefore, it has been studied to expose the electrode from the upper surface of the resin casing, which is the opposite surface of the bottom surface of the resin casing from which the heat sink is exposed. However, if the electrodes are exposed from the top surface of the resin casing, the electrodes are concentrated on the top surface of the resin casing, and in a resin-sealed power module that requires downsizing, a sufficient creepage distance between the electrodes can be secured. It becomes difficult. Therefore, there has been a problem that the insulating characteristics between the electrodes deteriorate.

  Here, in order to extend the creeping distance between the electrodes, it is conceivable to deform the upper surface of the resin housing between the electrodes so as to be non-planar. However, since the release sheet is used in the process of Patent Document 1, the upper surface of the resin casing is flat. Further, in the process of Patent Document 2, a step of cutting the columnar electrode is necessary, and it is difficult to deform the upper surface of the package. Therefore, the process disclosed in Patent Document 1 or Patent Document 2 has a problem that a resin-encapsulated power module having good insulation characteristics and the like cannot be manufactured by a simple method.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to manufacture a resin-encapsulated power module having good insulation characteristics and the like by a simple method.

  A resin-encapsulated power module according to the present invention includes an insulating substrate, a power semiconductor element disposed on the insulating substrate, a plurality of hollow cylindrical sockets disposed on the insulating substrate, and a plurality of recesses on the upper surface. And a resin housing formed to cover the power semiconductor element and the plurality of hollow cylindrical sockets. The plurality of hollow cylindrical sockets are exposed from the plurality of recesses such that one hollow cylinder socket of the plurality of hollow cylinder sockets is exposed from one recess of the plurality of recesses.

  A method for manufacturing a resin-encapsulated power module according to the present invention includes a step of fixing a power semiconductor element and a plurality of hollow cylindrical sockets on an insulating substrate, and an elasticity so as to block the openings in the openings of the plurality of hollow cylindrical sockets. A step of inserting the body cap jig, and clamping so that the upper mold is in contact with the cap jig and the cap jig is pushed toward the insulating substrate, and the lower mold is in contact with the bottom surface of the insulating substrate. And a step of resin-sealing the power semiconductor element and the plurality of hollow cylindrical sockets by a transfer molding method, and a step of removing the cap jig from the plurality of hollow cylindrical sockets. .

  According to the present invention, it is possible to manufacture a resin-encapsulated power module having good insulation characteristics by a simple method.

1A and 1B are a sectional view and a plan view of a resin-sealed power module according to an embodiment of the present invention. It is a flowchart explaining the manufacturing method of a resin-sealed power module. It is a figure which shows a to-be-molded object. It is a figure which shows a mode that the cap jig | tool was inserted in the hollow cylindrical socket. It is a figure which shows the example of a dimension of each part of a cap jig | tool. It is a figure which shows the state by which the to-be-molded object has been arrange | positioned at the lower metal mold | die. It is a figure which shows the state clamped by the upper metal mold | die and the lower metal mold | die.

  An embodiment according to the present invention will be described with reference to FIGS. In addition, the same code | symbol may be attached | subjected to the same or corresponding component, and description of description may be abbreviate | omitted.

  1A and 1B are a sectional view and a plan view of a resin-sealed power module 10 according to an embodiment of the present invention. The resin-encapsulated power module 10 includes a metal substrate 12 made of copper that functions as a heat sink and has good thermal conductivity. A circuit pattern 16 is formed on the metal substrate 12 via an insulating layer 14. The insulating layer 14 is made of a high thermal conductivity type epoxy resin. A thin copper plate is used for the circuit pattern 16. Since the metal substrate 12, the insulating layer 14, and the circuit pattern 16 are integrally joined, they may be collectively referred to as an insulating substrate 18.

  The power semiconductor element 20 is fixed to the circuit pattern 16 with solder. That is, the power semiconductor element 20 is disposed on the insulating substrate 18. The power semiconductor element 20 is, for example, an IGBT or a diode. A hollow cylindrical socket 24 is further fixed to the circuit pattern 16 with solder. That is, as shown in FIG. 1, a plurality of hollow cylindrical sockets 24 are arranged on the insulating substrate 18. The hollow cylindrical socket 24 is an external connection terminal of the resin-encapsulated power module 10 and is formed of copper. An opening (hole) is formed in the hollow cylindrical socket 24. This opening is provided so that an electrical connection with an external configuration can be easily obtained using, for example, a press-fit terminal. The opening of the hollow cylindrical socket 24 faces the outside of the resin-sealed power module 10. The power semiconductor element 20 and the circuit pattern 16 to which the hollow cylindrical socket 24 is fixed are electrically connected by an aluminum metal wire 22.

  A resin casing 26 is formed by resin sealing so as to cover each component (excluding a part) shown in FIG. A plurality of recesses 28 are formed on the upper surface of the resin casing 26. As shown in FIG. 1, the plurality of recesses 28 have a shape having a slope and a bottom surface. More specifically, the width of the recess 28 becomes narrower toward the inside of the resin casing 26. The openings of the hollow cylindrical socket 24 are exposed from the plurality of recesses 28. Here, the plurality of hollow cylindrical sockets 24 are exposed from the plurality of recesses 28 such that one hollow cylinder socket 24 of the plurality of hollow cylinder sockets 24 is exposed from one recess 28 of the plurality of recesses 28. As a result, a recess 28 exists between the hollow cylindrical socket 24 and the other hollow cylindrical socket 24. Therefore, the creeping distance between the hollow cylindrical sockets 24 can be increased.

  The bottom surface of the metal substrate 12 is exposed on the bottom surface of the resin casing 26. Thereby, the metal substrate 12 can function as a heat sink.

  FIG. 2 is a flowchart illustrating a method for manufacturing the resin-encapsulated power module 10. Hereinafter, a method for manufacturing the resin-encapsulated power module 10 will be described with reference to the flowchart of FIG. First, an object to be molded (insert) is assembled (step 50). The object to be molded is a structure that is covered with a resin in a later process. FIG. 3 is a view showing the object to be molded. The power semiconductor element 20 and the hollow cylindrical socket 24 are fixed onto the circuit pattern 16 in the insulating substrate 18 by using solder reflow. The circuit pattern 16 and the electrode on the surface of the power semiconductor element 20 are ultrasonically bonded with an aluminum metal wire 22. In place of the metal wire 22, an aluminum ribbon or a copper lead may be used for bonding.

  When the process of step 50 is completed, the process proceeds to step 52. Step 52 is a step of inserting the cap jig 30 into the hollow cylindrical socket 24. FIG. 4 is a diagram illustrating a state where the cap jig 30 is inserted into the hollow cylindrical socket 24. The cap jig 30 is made of a highly elastic material such as silicone rubber or fluorine rubber. FIG. 5 shows an example of dimensions of each part of the cap jig 30. As shown in FIG. 5, the cap jig 30 includes a non-insertion portion 32 and an insertion portion 34. The non-insertion portion 32 is a portion that is not inserted into the opening of the hollow cylindrical socket 24, and the insertion portion 34 is a portion that is inserted into the opening of the hollow cylindrical socket 24. The non-insertion portion 32 has a flat upper surface, and is in surface contact with an upper mold described later on the flat upper surface. The non-insertion portion 32 is also a portion that determines the shape of the recess 28 (see FIG. 1) of the resin housing. Therefore, the non-insertion portion 32 has a shape that can form the slope and bottom surface of the recess 28.

  The outer diameter of the insertion portion 34 is equal to the inner diameter of the opening of the hollow cylindrical socket 24. Further, the insertion portion 34 has a tapered shape at the tip so that the insertion into the hollow cylindrical socket 24 is easy. The dimensions of the hollow cylindrical socket 24 corresponding to the cap jig 30 having the dimensions shown in FIG. 5 are, for example, an inner diameter φ1.70 mm, an outer diameter φ2.70 mm, and a length 5.0 mm. The cap jig 30 having such a shape and material is inserted so as to close the openings of the plurality of hollow cylindrical sockets 24. As shown in FIG. 4, the height of the molding object before insertion of the cap jig 30 is represented by A. When the cap jig 30 is inserted, this height rises to a height indicated by B (see FIG. 4).

  When the process of step 52 is completed, the process proceeds to step 54. In step 54, the object to be molded with the cap jig 30 inserted is placed in the lower mold 40. FIG. 6 is a view showing a state in which the object to be molded is arranged in the lower mold 40. The object to be molded with the cap jig 30 inserted is placed on the lower mold 40 at a high temperature (170 to 180 ° C.) for transfer molding. And in order to raise a to-be-molded object from room temperature to the temperature equivalent to a metal mold | die, it is left to stand for several minutes.

  When the process of step 54 is finished, the process proceeds to step 56. Step 56 is a process in which the upper mold 42 and the lower mold 40 are clamped. FIG. 7 is a view showing a state in which the upper mold 42 and the lower mold 40 are clamped. As shown in FIG. 7, when the mold is clamped, the upper mold 42 is in contact with the cap jig 30 and presses the cap jig 30 toward the insulating substrate 18. At this time, the lower mold 40 is in contact with the bottom surface of the insulating substrate 18. Here, the height in the cavity formed by the upper mold 42 and the lower mold 40 is defined as X (see FIG. 7). In the embodiment according to the present invention, the object to be molded and the cap jig 30 are formed so that X is larger than A and smaller than B in FIG. These dimensions are appropriately determined so as to meet each condition described later.

  In this way, by clamping with the lower mold 40 and the upper mold 42, distortion occurs on the upper surface (top surface) of the cap jig 30. This distortion occurs when the cap jig 30 is pressed against the hollow cylindrical socket 24 by the upper mold 42. The pressure due to this strain becomes larger than 5 MPa to 30 MPa which is an injection pressure by a transfer molding method described later. Such a strain is intentionally generated using the cap jig 30 which is an elastic body. When the stress higher than the injection pressure is generated in the cap jig 30, the gap between the non-insertion portion 32 of the cap jig 30 and the upper end of the hollow cylindrical socket 24 is filled.

  When the process of step 56 is finished, the process proceeds to step 58. Step 58 is a step of performing a transfer molding method. The outline of the process of the transfer mold method is as follows. First, a resin such as an epoxy resin used in the transfer molding method is heated and melted and injected into the cavity in a low viscosity state. This process is called an injection process. Then, the resin is cured and reacted while the pressure is maintained after the resin is filled into the cavity. This process is called a pressure holding process.

  Since the hollow cylindrical socket 24 is capped by the cap jig 30 sandwiched between the hollow cylindrical socket 24 and the upper mold 42, the low-viscosity molten resin is contained in the hollow cylindrical socket 24 in the injection process. Does not flow into. Here, an injection pressure is applied to the cap jig 30 in the pressure holding step. However, as described above, the cap jig 30 is distorted more than the injection pressure, so that the molten resin does not flow into the hollow cylindrical socket 24 even in the pressure holding process. Thus, in step 58, the resin casing is formed by the transfer molding method.

  When the process of step 58 is completed, the process proceeds to step 60. Step 60 is a step of removing the upper mold 42, the lower mold 40, and the cap jig 30 from the object to be molded. After the resin constituting the resin casing 26 (see FIG. 1) is sufficiently cured, the upper mold 42 and the lower mold 40 are opened. At this time, the cap jig 30 held by the upper mold 42 is restored to its original thickness and released. When the released cap jig 30 is removed from the hollow cylindrical socket 24, a recess 28 is formed in the resin casing 26. Further, the non-insertion portion 32 of the cap jig 30 is formed with a gradient at a portion in contact with the mold resin. Therefore, the cap jig 30 can be easily detached from the resin casing 26.

  When step 60 is completed, the resin-encapsulated power module 10 shown in FIG. 1 is completed, and the process ends.

  The resin-sealed power module 10 according to the embodiment of the present invention has a configuration in which one hollow cylindrical socket 24 is exposed from one recess 28 of the resin casing 26. Therefore, the creeping distance between the hollow cylindrical socket 24 and the other hollow cylindrical socket 24 is increased by the amount of the recess 28. Therefore, the resistance of the upper surface of the resin casing 26 can be increased to suppress surface discharge. Moreover, since the recessed part 28 has an inclined surface and a bottom face and lengthens the distance from the hollow cylindrical socket 24 to the resin housing | casing 26 upper surface, it can improve a tracking resistance characteristic.

  In the embodiment according to the present invention, the cap jig 30 is used when performing the transfer molding method. The cap jig 30 is inserted into the hollow cylindrical socket 24 and is not a sheet-like material such as a releasable sheet. Therefore, the sheet does not block the air vent, and it can be prevented that a void is generated in the resin casing.

  In the embodiment according to the present invention, the shape of the recess 28 formed in the resin casing 26 can be freely deformed by the shape of the non-insertion portion 32 of the cap jig 30. Therefore, it is possible to easily obtain the shape of the recess 28 that satisfies the required characteristics according to the specifications of the resin-encapsulated power module 10. Therefore, the resin-sealed power module 10 with good insulation characteristics can be manufactured. Further, if only the arrangement of the external connection terminals (hollow cylindrical socket 24) is changed, it is not necessary to change the mold, so that the cost can be reduced when the design is changed.

  In the embodiment according to the present invention, a cap jig 30 made of an elastic body is used when performing the transfer molding method. The cap jig 30 is pressed by the upper mold 42 with a pressure larger than the injection pressure. Therefore, it is possible to prevent the resin from entering the hollow cylindrical socket 24.

  The cap jig 30 is preferably made of a material having a compressive modulus of 20 MPa to 1000 MPa and a compressive strength of 20 MPa or more in a temperature range from room temperature to the temperature of the transfer molding method, but is not limited thereto.

  In addition, various modifications can be made without departing from the characteristics of the present invention.

  DESCRIPTION OF SYMBOLS 10 Resin type | mold power module, 18 Insulation board | substrate, 20 Power semiconductor element, 22 Metal wire, 24 Hollow cylindrical socket, 26 Resin housing | casing, 28 Recessed part, 30 Cap jig | tool, 40 Lower mold, 42 Upper mold

Claims (8)

An insulating substrate;
A power semiconductor element disposed on the insulating substrate;
A plurality of hollow cylindrical sockets disposed on the insulating substrate;
A plurality of recesses are formed on the upper surface, and the resin housing is formed so as to cover the power semiconductor element and the plurality of hollow cylindrical sockets,
The plurality of hollow cylindrical sockets are exposed from the plurality of recesses such that one hollow cylinder socket of the plurality of hollow cylindrical sockets is exposed from one recess of the plurality of recesses. Type power module.   The resin-encapsulated power module according to claim 1, wherein the width of the concave portion becomes narrower toward the inside of the resin casing. Fixing a power semiconductor element and a plurality of hollow cylindrical sockets on an insulating substrate;
Inserting a cap jig so as to close the openings in the openings of the plurality of hollow cylindrical sockets;
The upper mold is in contact with the cap jig and the cap jig is pushed toward the insulating substrate, and the mold is clamped so that the lower mold is in contact with the bottom surface of the insulating substrate;
A step of resin-sealing the power semiconductor element and the plurality of hollow cylindrical sockets by a transfer mold method;
And a step of removing the cap jig from the plurality of hollow cylindrical sockets.   4. The stress of pressing the cap jig against the plurality of hollow cylindrical sockets by the upper mold in the resin sealing step is higher than an injection pressure by the transfer molding method. Manufacturing method of resin-sealed power module.   5. The method for manufacturing a resin-encapsulated power module according to claim 3, wherein the cap jig has a non-insertion portion in surface contact with the upper mold.   6. The cap jig according to claim 3, wherein the cap jig has an insertion portion to be inserted into the opening of the hollow cylindrical socket, and an outer diameter of the insertion portion is equal to an inner diameter of the opening of the hollow cylindrical socket. A method for producing a resin-encapsulated power module according to claim 1.   The method for manufacturing a resin-encapsulated power module according to claim 3, wherein the insertion portion has a tapered shape.   8. The cap jig according to claim 3, wherein the cap jig is a material having a compressive elastic modulus of 20 MPa to 1000 MPa and a compressive strength of 20 MPa or more in a temperature range from room temperature to a temperature of a transfer molding method. 2. A method for producing a resin-encapsulated power module according to item 1.

Images