JP2015046503A - Electronic module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic module excellent in heat radiation performance.SOLUTION: An electronic module 1 comprises: a wiring board 2 on which a wiring pattern is formed; a semiconductor package 3 including a main body section 31 including a semiconductor chip 311 (junction) and a prescribed number of leads 32 extending from the main body section 31, provided on the wiring board 2; and a heat radiation member 4 provided on the wiring board 2 so as to cover the periphery of the semiconductor package 3. The leads 32 of the semiconductor package 3 are joined with a wiring pattern of the wiring board 2 by soldering, and at least part of the heat radiation member 4 is joined with the wiring pattern of the wiring board 2 by soldering. The heat radiation member 4 is arranged in the state of not touching the main body section 31 of the semiconductor package 3, and a channel 8 is formed therein that circulates cooling wind between the heat radiation member 4 and the main body section 31.

Description

  The present invention relates to an electronic module, and more particularly to a technique for efficiently radiating heat generated from an electronic component mounted on the electronic module.

  With high performance / high output of electronic components, high output electronic components such as power semiconductors are often mounted on electronic devices on which such electronic components are mounted. For this reason, such electronic devices have been required to have higher heat dissipation performance than before.

  Regarding the heat dissipation structure of an electronic device, for example, in Patent Document 1, in order to improve the heat dissipation effect, the semiconductor package radiator is used to conduct heat generated in the semiconductor package attached to the printed board. A heat transfer body provided in contact with a die, a foot projecting from the heat transfer body to fix the heat transfer body in a through hole formed in the printed board, and the heat transfer body In order to dissipate the heat transmitted through the air, it is described that a heat dissipating fin which is formed as a component separate from the heat transfer body and is fixed to the heat transfer body is provided.

  Further, in Patent Document 2, in a hybrid integrated circuit device in which a circuit unit including a vertical power semiconductor element (power element) having electrodes formed on both surfaces is formed on a substrate, one electrode is electrically connected to the substrate. It is described that the other electrode is electrically connected to the case, the power semiconductor element is radiated in the case, and the other electrode is electrically connected to the outside through the case.

JP-A-4-039957 JP-A-7-263618

  FIG. 4 is a partial cross-sectional view of the electronic module 70 for explaining the heat dissipation structure of the surface mount type electronic module. As shown in the figure, the electronic module 70 includes a flat wiring board 72, a semiconductor package 73 disposed at a predetermined position on the surface of the wiring board 72, and a base plate 75 provided in parallel with the wiring board 72. . Note that the base plate 75 is a constituent member of a housing in which the electronic module 70 is accommodated, for example.

  The semiconductor package 73 includes a main body portion 731 configured by resin-sealing a semiconductor chip 7311 (junction), and a predetermined number of leads 732 made of a conductive metal material extending from the main body portion 731. The vicinity of the end of each lead 732 is soldered and joined to a land 721 formed as a wiring pattern on the wiring board 72. Thus, the semiconductor chip 7311 is electrically connected to the wiring pattern of the wiring board 72 and is also thermally coupled to the wiring board 72 due to the high thermal conductivity of each lead 732.

  The upper surface of the main body portion 731 of the semiconductor package 73 is in surface contact with the lower surface 752 of a rectangular parallelepiped convex portion 751 that hangs down from the base plate 75 via a heat transfer member 74 such as a heat conductive sheet.

  Here, in the electronic module 70 shown in the figure, the thermal resistance between the semiconductor chip 7311 (junction) of the semiconductor package 73 and the main body portion 731 is large, and the main body portion of the semiconductor package 73 is interposed via the heat transfer member 74. A sufficient heat dissipation effect cannot always be obtained simply by bringing the upper surface of 731 into surface contact with the base plate 75. The heat of the semiconductor chip 7311 (junction) is transmitted to the wiring board 72 mainly by the heat conduction through the lead 732 having high thermal conductivity and through the soldering pad immediately below the semiconductor chip 7311. If the heat capacity of the wiring board 72 is insufficient compared with the heat generation amount of the semiconductor package 73, the semiconductor package 73 cannot be sufficiently cooled, and it is necessary to take another measure such as using a heat sink. It leads to increase.

  The present invention has been made in view of such a background, and an object thereof is to provide an electronic module having excellent heat dissipation performance.

One aspect of the present invention for achieving the above object is an electronic module,
A wiring board on which a wiring pattern is formed;
A semiconductor package having a main body portion including a semiconductor chip and a predetermined number of leads extending from the main body portion, provided on the wiring board;
A heat dissipating member provided on the wiring board so as to cover the periphery of the semiconductor package;
With
The lead of the semiconductor package is soldered and joined to the wiring pattern of the wiring board,
At least a part of the heat dissipation member is soldered and joined to the wiring pattern of the wiring board,
The heat dissipating member is disposed in a non-contact state with the main body portion of the semiconductor package, and a flow path for flowing cooling air is formed between the heat dissipating member and the main body portion.

  Another aspect of the present invention is the above electronic module, wherein at least a part of the heat dissipation member is soldered and joined to a land formed on the wiring board.

  Another aspect of the present invention is the above electronic module, wherein at least a part of the heat dissipation member is soldered and joined to a through hole formed in the wiring board.

  Another aspect of the present invention is the electronic module, wherein at least a part of the heat radiating member is thermally coupled to a housing in which the electronic module is provided.

  Another aspect of the present invention is the electronic module described above, wherein a vent hole through which the cooling air flows is formed in at least a part of the heat radiating member.

  In addition, the subject which this application discloses, and its solution method are clarified by the column of the form for inventing, and drawing.

  ADVANTAGE OF THE INVENTION According to this invention, the electronic module excellent in the heat dissipation performance can be provided.

It is a figure explaining the heat dissipation structure of the electronic module. FIG. 3 is a diagram showing a state of heat transfer in the electronic module 1. It is a figure which shows the other structure of the electronic module. It is a figure explaining the heat dissipation structure of the surface mount type electronic module.

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

  FIG. 1 is a diagram illustrating a heat dissipation structure of an electronic module 1 according to an embodiment of the present invention, and is a partial cross-sectional view of the electronic module 1. The electronic module 1 is, for example, a DC-DC converter, a switching power supply, or the like, and includes various electronic components (semiconductor package, power transistor, power diode, inductor (coil), transformer, etc.).

  As shown in the figure, an electronic module 1 includes a flat wiring board 2 and a semiconductor package arranged by surface mounting (SMT (Surface Mount Technology)) at a predetermined position on the surface (+ Z side surface) of the wiring board 2. 3, a heat dissipating member 4, and a base plate 5 provided in parallel with the wiring board 2 and having a flat surface 51 on at least the wiring board 2 side (−Z side). The base plate 5 is, for example, a part of the structure of the housing that houses the electronic module 1.

  The wiring board 2 is a rigid type or a rigid flexible type printed wiring board (PCB: Printed Circuit Board). The wiring board 2 is based on an insulating material (paper phenol, paper epoxy, glass composite, glass / epoxy, etc.) and has a structure in which a conductive layer made of metal or the like and an insulating coating layer are laminated in this order. The surface (+ Z side surface) of the wiring substrate 2 includes a predetermined wiring pattern (pads, lands, etc.) by removing the insulating coating layer and exposing the conductive layer to the surface. Including those that do not.).

  The semiconductor package 3 includes a main body portion 31 formed by resin-sealing a semiconductor chip 311 (junction), and a predetermined number of leads 32 made of a metal material having high thermal conductivity and extending from the semiconductor chip 311. Have. The vicinity of the end of each lead 32 is soldered and joined to a land 21 formed as a wiring pattern on the wiring board 2. As a result, the semiconductor chip 311 is electrically connected to the wiring pattern of the wiring board 2 and is also thermally coupled to the wiring board 2 due to the high thermal conductivity of each lead 32. Further, the semiconductor chip 311 generally has a metal part exposed at the lower part of the semiconductor body, and this part can be soldered to a soldering pad or the like of the wiring board 2, and in this case, the metal part is also interposed. The semiconductor chip 311 is thermally coupled to the wiring board 2. In addition, it is preferable to use a solder having a high thermal conductivity as much as possible as the solder (brazing material) used for the soldering.

  The heat dissipation member 4 is configured using a material having high thermal conductivity (for example, aluminum, copper, or an alloy including at least one of them). As shown in the figure, the heat dissipation member 4 has a shape that covers the periphery of the semiconductor package 3 in a non-contact state with the main body portion 31 of the semiconductor package 3 (in this example, the heat dissipation member 4 has a substantially rectangular parallelepiped shape). ing). A pair of opposing side surfaces (side surfaces on the + X side and −X side) of the substantially rectangular parallelepiped shape of the heat radiating member 4 are open, so that the X axis direction (from + X direction) is between the heat radiating member 4 and the main body portion 31. A flow path 8 through which cooling air flows in the −X direction or the −X direction to the + X direction) is formed. Note that air that is pumped by a cooling fan or the like provided in a housing in which the electronic module 1 is accommodated flows through the flow path 8.

  The heat radiating member 4 may have a shape in which all four sides are surrounded by side surfaces (a shape in which none of the side surfaces are open). In that case, the flow path 8 passing through the inside and outside of the heat radiating member 4 can be realized, for example, by forming a large number of vent holes having a predetermined shape on the side surface of the heat radiating member 4. The heat radiating member 4 only needs to have a shape that covers at least the body portion 31 of the semiconductor package 3 in a non-contact state, and may be, for example, a substantially cylindrical shape.

  As shown in the figure, the vicinity of the bottom portion of the side surface of the heat radiating member 4 is bent in an L shape on the outer peripheral side of the heat radiating member 4, whereby a bent portion for placing the heat radiating member 4 on the surface of the wiring board 2. 41 is formed.

  The heat dissipating member 4 is disposed so that the bent portion 41 overlaps the land 22 which is the wiring pattern of the wiring substrate 2, and is fixed to the wiring substrate 2 by soldering the bent portion 41 to the pad 22. Thereby, the heat radiating member 4 is thermally coupled to the wiring board 2. In addition, it is preferable to use a solder having a high thermal conductivity as much as possible as the solder (brazing material) used for the soldering.

  The upper surface (+ Z side surface) of the heat dissipation member 4 is directly or indirectly through a heat transfer member (for example, a thin heat conductive sheet (resin sheet, metal sheet, etc.), heat conductive grease, etc.) It is in surface contact with the flat surface 51 of the base plate 5. A structure (radiation fin, groove structure, etc.) for enlarging the surface area of the heat dissipation member 4 to a predetermined part (inner peripheral surface, outer peripheral surface, upper surface of the bent portion 41 (+ Z side surface), etc.) of the heat dissipation member 4. May be provided.

  FIG. 2 shows a state of heat transfer in the electronic module 1 having the above-described configuration (a state in which heat generated from the semiconductor chip 311 (junction) is transferred). In addition, the arrow line shown to the figure shows the flow of heat.

  As shown in the figure, the heat generated from the semiconductor chip 311 is efficiently transmitted to the wiring board 2 via the leads 32 and the lands 21. Part of the heat of the main body portion 31 of the semiconductor package 3 is transmitted to the air flowing through the wiring board 2 and the flow path 8.

  The heat transmitted to the wiring board 2 is efficiently transmitted to the heat radiating member 4 through the lands 22, and a part of the heat is cooled by the cooling air flowing inside or outside the flow path 8. Further, another part of the heat of the heat radiating member 4 is transmitted to the base plate 5. As described above, the heat generated from the semiconductor chip 311 (junction) is efficiently transmitted to the wiring board 2 and the base plate 5, whereby the semiconductor chip 311 is efficiently cooled.

  Since the heat radiating member 4 is arranged in a non-contact state with the main body portion 31 of the semiconductor package 3, all of the main body portion 31, the lead 32, the wiring board 2, and the heat radiating member 4 are inside or outside the flow path 8. Thus, the heat generated from the semiconductor chip 311 is efficiently cooled by the entire electronic module 1.

  As described above, the electronic module 1 of the present embodiment has high heat dissipation performance. For this reason, it is applicable also to the electronic module 1 in which high output electronic components, such as a power semiconductor, are mounted. Moreover, since high heat dissipation efficiency is obtained, for example, electronic components can be densely arranged on the wiring board 2 to increase mounting efficiency, and the electronic module 1 can be downsized.

  In addition, the above description is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

  For example, in the above-described embodiment, the heat radiating member 4 is fixed to the wiring board 2 by soldering the bent portion 41 of the heat radiating member 4 to the land 22. For example, as shown in FIG. May be provided on the wiring board 2 by inserting the legs 45 provided on the bottom thereof into the through holes 25 provided on the wiring board 2 and soldering the periphery of the legs 45. Other configurations of the electronic module 1 shown in the figure are the same as those in the above-described embodiment. In such a configuration, the heat radiating member 4 can be securely fixed to the wiring board 2. Further, since it is not necessary to form a pad for attaching the heat dissipation member 4 to the surface of the wiring board 2, the mounting space of the wiring board 2 can be used effectively.

  DESCRIPTION OF SYMBOLS 1 Electronic module, 2 Wiring board, 3 Semiconductor package, 31 Main part, 32 Lead, 311 Semiconductor chip, 4 Heat radiation member, 41 Bending part, 5 Base plate, 21 Land, 22 Land, 8 Flow path, 25 Through hole

Claims (5)

A wiring board on which a wiring pattern is formed;
A semiconductor package having a main body portion including a semiconductor chip and a predetermined number of leads extending from the main body portion, provided on the wiring board;
A heat dissipating member provided on the wiring board so as to cover the periphery of the semiconductor package;
With
The lead of the semiconductor package is soldered and joined to the wiring pattern of the wiring board,
At least a part of the heat dissipation member is soldered and joined to the wiring pattern of the wiring board,
The heat dissipating member is disposed in a non-contact state with the main body portion of the semiconductor package, and a flow path for circulating cooling air is formed between the heat dissipating member and the main body portion. . The electronic module according to claim 1,
An electronic module, wherein at least a part of the heat radiating member is soldered and joined to a land formed on the wiring board. The electronic module according to claim 1 or 2,
An electronic module, wherein at least a part of the heat radiating member is soldered and joined to a through hole formed in the wiring board. The electronic module according to any one of claims 1 to 3,
An electronic module, wherein at least a part of the heat radiating member is thermally coupled to a housing in which the electronic module is provided. The electronic module according to any one of claims 1 to 4,
An electronic module, wherein a ventilation hole through which the cooling air flows is formed in at least a part of the heat radiating member.

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