JPH0897329A - Device having electronic device therein - Google Patents

Abstract

PURPOSE: To provide a device having an electronic device mounted therein, having high reliability of electrical connection and satisfactory electrical property of the package. CONSTITUTION: An electronic device is composed of a wiring board 1 having a conductive pattern 11 formed on the surface thereof and having an electronic component housing through-hole 12 formed therein, a metallic radiation plate 5 fixed on one surface of the wiring board with an adhesive, an electronic component 2 mounted on the radiation plate 5, plural lead frames 4 connected with one end of the conductive pattern electrically connected with the electronic component, and a mold resin encapsulation portion 8 for encapsulating the electronic component. A through-hole 51a is formed in the metallic radiation plate 5, and a solder 7 is provided in the through-hole 51a. The conductive pattern 11 on the wiring board and the metallic radiation plate 5 are electrically connected with each other by the solder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting apparatus, and more particularly to an electronic component mounting apparatus having excellent reliability of electrical connection and excellent package electrical characteristics.

[0002]

2. Description of the Related Art With the miniaturization and high performance of electronic equipment, electronic component mounting devices are also increasing in pin count, miniaturization, and surface mounting. Electronic component packages for surface mounting are generally Q
FP (Quad Flat Package), PLCC
(Plastic Leaded Chip Carrier), etc.
Many use so-called lead frames. Among these, the electronic components (semiconductor chips) mounted are
As the number of pins is increased, the size is reduced, the density is increased, and the frequency is increased, the inner side of the package is required to have a narrower pitch, heat dissipation, and electrical characteristics. As a method of satisfying the requirement, a lead frame is arranged on one surface of the wiring board, and the wiring board and the heat sink are electrically connected. This is because by electrically connecting the conductive pattern (conductor circuit) of the wiring board, particularly the power supply circuit or the ground circuit, to the heat dissipation member, the electrical characteristics of the package can be improved and grounding can be performed. is there. As a method of electrically connecting both,
As shown in FIG. 9, the solder 6 is attached to the lower portion of the side wall of the heat dissipation member 5.
There is known a structure in which both are joined by c and the surface is covered with a resin 6d (Japanese Patent Laid-Open No. 23522/1993).
3 gazette).

[0003]

However, in the case of the above-mentioned solder joint, the solder portion 6c and the resin portion 6d covering the solder portion 6c.
Adhesion with is not enough. Further, the solder portion 6c is melted by heating in the reflow process when the completed electronic component mounting device is mounted on the motherboard. Therefore, the adhesion between the solder portion and the resin portion is reduced. When a high melting point solder that does not melt is used, heating at the time of soldering the heat dissipation plate requires a high temperature, and the wiring board made of resin is thermally deteriorated, causing delamination and the like in the wiring board. Also,
Even when the side wall of the heat sink is bonded with the solder 6a as shown in FIG. 7, the adhesion between the mold resin portion 8 and the solder portion 6a is reduced. In particular, due to heating when mounting the electronic component mounting device on the motherboard, the adhesiveness between the solder portion 6a and the mold resin portion 8 deteriorates. Further, the deterioration of the moisture resistance of the package increases the occurrence of package cracks.

The present invention overcomes the above-mentioned drawbacks, and an object of the present invention is to provide an electronic component mounting apparatus having excellent reliability of electrical connection and excellent package electrical characteristics.

[0005]

In order to achieve the above-mentioned object, the present inventor diligently studied a method for electrically connecting a conductive pattern on a wiring board and a heat dissipation member. For example, as this method, as shown in FIG. 8, a method of electrically bonding the metal heat sink 5 and the predetermined conductive pattern 11 by using a conductive adhesive 6b can be considered. This conductive adhesive is a metal filler (Ag, Au, Cu) having conductivity.
Etc.) containing a resin as a binder and exhibiting conductivity by contact between metal fillers. But,
In this method, heat deterioration, moisture absorption, and expansion / contraction of the resin occur in environmental tests such as heating, humidification, and temperature cycle. As a result, the contact between the metal fillers is weakened, the conduction resistance is increased, and the function of connection cannot be achieved in the circuit.

An electronic component mounting apparatus according to the first aspect of the present invention is a wiring board having a through hole for accommodating an electronic component and having a conductive pattern formed on at least a surface thereof, and a penetrating hole for accommodating the electronic component on one surface of the wiring board. A metal heat sink fixed by an adhesive so as to cover the hole, an electronic component mounted in the electronic component housing through hole and on the metal heat sink, and electrically connected to the electronic component. Also, a plurality of lead frames connected to one end of the conductive pattern, the electronic component,
In the electronic component mounting device including the wiring board, the side wall portion of the metal heat sink and the mold resin sealing portion that seals the inner lead portion of the lead frame, a through hole is formed in the metal heat sink. The solder is arranged in the through hole, and the conductive pattern on the wiring board and the metal heat dissipation plate are electrically connected by the solder.

In the electronic component mounting apparatus of the second aspect of the present invention, a wiring board having a conductive pattern formed on at least the surface thereof and having a through hole for storing an electronic component, and being fixed on one surface of the wiring board with an adhesive, A metal radiator plate having a protrusion inserted into the through hole for storing electronic components, an electronic component mounted on the protrusion of the metal radiator plate, and electrically connected to the electronic component, A plurality of lead frames connected to one end of the conductive pattern, a mold resin sealing portion that seals the electronic component, the wiring board, the side wall portion of the metal heat sink and the inner lead portion of the lead frame. In the electronic component mounting apparatus consisting of, a through hole is formed in the metal heat dissipation plate, solder is placed in the through hole, and the conductive pattern and the metal pattern on the wiring board are arranged by the solder. Characterized by electrically connecting the hot plate.

In the first and second inventions, a groove portion, which is connected to the through hole and is open at both ends, is formed on one surface side of the metal heat radiating plate, and inside the groove portion and the through hole. The inside of the hole may be filled with the mold resin.

As the above-mentioned "metal heat dissipation plate", a metal such as copper or aluminum having excellent thermal conductivity or an alloy based on the metal can be used. Of these, copper and copper alloys are preferable in consideration of solderability. If the size of the "through hole" provided in this is too large, the heat capacity of the heat sink will be small and the heat dissipation of the package will be poor, but if it is too small, it will be difficult to form a sufficient solder fillet, In some cases, the attachability is not sufficient.
Usually, the size of this through hole is 1 to 5 m if it is a circle.
In the case of m and square sides, one side is preferably 1 to 10 mm. Within this range, the performance balance between heat dissipation and solderability of the package is excellent. This through hole can be easily formed by drilling, punching with a die or the like.

The "solder" is usually Sn / P
b type, Sn-Zn type, etc. are used. Especially Sn: Pb
= 9: 1 is preferable considering the heat resistance of the wiring board and the heat resistance of the soldered solder of the heat sink. That is, it is preferable that the package is hard to be remelted at the soldering temperature when the package is soldered to the mother board in the later step.

[0011]

In this electronic component mounting apparatus, the metal heat sink and the conductive pattern of the wiring board are electrically connected using solder. Therefore, as compared with the case of using a conductive adhesive, the reliability of electrical connection is excellent and the deterioration thereof is less. Further, in this mounting apparatus, a through hole is provided in this heat dissipation plate, and both are soldered through this hole. Therefore, since the mold resin sealing portion and the solder portion are not in contact with each other and the mold resin portion and the heat sink are in direct contact with each other, the adhesion between the mold resin portion and the heat sink is good and the solder portion is It does not peel off.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples. (1) Configuration of Electronic Component Mounting Device The electronic component mounting device of this embodiment, as shown in FIGS. 1 and 2, has a wiring board 1 and one electronic component (semiconductor chip).
2, a bonding wire 3, a lead frame 4 having a plurality of leads, a heat dissipation plate 5, and a mold resin sealing portion 8.
Consists of. The wiring board 1 is made of glass cloth / epoxy resin and has a size of 25.0 mm × 25.0 mm ×
It is 0.2 (thickness) mm. Instead of the glass cloth / epoxy resin, a material composed of glass cloth and a heat resistant resin such as bismaleimide / triazine resin or polyimide may be used. A predetermined conductive pattern (made of copper foil) 11 is formed on this surface. In addition, the conductive pattern 11 is formed by usual etching,
A plating layer of nickel / gold or the like is applied to this surface.

The wiring board 1 has an electronic component [size;
10.0 mm x 10.0 mm x 0.4 (thickness) mm] 2
Is provided with a through hole 12 for accommodating the. The conductive patterns 11 are formed on both sides of the wiring board 1,
The conductive pattern 11 is formed at least at a position in contact with the through hole 12. Although the conductive patterns 11 are usually formed at all positions of the four through holes 51 as shown in the drawing, the present invention is not limited to this, and the conductive patterns 11 may be formed at at least one position.

A heat sink [18.0 mm × 18.0]
mm × 1.0 to 2.0 (thickness) mm, for example, tough pitch copper. ] 5 is a flat plate as shown in FIG. 2, and four through holes (about 1 to 2 mmφ) 51a in the four corner directions.
Are formed at positions of about 1 mm from the end faces. The heat dissipation plate 5 is below the wiring board 1 and covers the through holes for mounting electronic components, so that the adhesive layer 6 is formed.
It is fixedly adhered by Nos. 1 and 61. The electronic component 2 is housed and arranged in the through hole 12 and is fixed to the heat sink 5 by an adhesive layer 62. Then, a solder portion 7 is formed on the bottom side in each of the four through holes 51 a, and the heat sink 5 and the conductive pattern 11 on the wiring board 1 are joined by the solder portion 7. The solder used was Sn: Pb = 9: 1. It has a melting point of about 210 ° C. and is heat resistant.
Further, the electronic component 2 is connected to the conductive pattern 11 formed on the other surface by the bonding wire 3.

The lead frame 4 has a conductive pattern 1
One end portion 11a of the lead frame 1 is connected to one end portion of the rectangular wiring board 1. Further, 208 leads of the lead frame extend outward in four directions of the rectangular wiring board 1. The thickness of each lead is 0.
The width is 15 mm, the width is 0.2 mm, and the outer lead pitch is 0.5 mm. This lead frame 4 is
A plurality of inner lead portions 41 located in the resin sealing portion 8
And a plurality of outer lead portions 42 located outside the resin sealing portion 8. The mold resin sealing portion 8 is
The electronic component 2, the bonding wire 3, the wiring board 1, the inner lead portion 41, and the outer wall (outer peripheral portion) of the heat dissipation plate 5 are covered and sealed. The resin sealing portion 8 has a thickness of 3
~ 4 mm.

(2) Method for manufacturing electronic component mounting device The heat radiating plate 5 having the through hole 51a on one surface (either surface is acceptable) of the wiring board 1 to which the lead frame 4 is joined.
Are bonded and fixed by the adhesive 61. The through hole 51a provided in the heat sink 5 is provided on a part of the conductive pattern (copper pattern plated with Au) 11 (the wiring pattern to be electrically connected to the heat sink) on the surface of the wiring board to be bonded. Positioned and glued as they come. At this time, the adhesive is adhered except for the through holes.

Next, a solder paste is applied to the through holes 51a by a dispenser or screen printing.
In this order, the heat dissipation plate 5 may be adhesively fixed after applying the solder paste on the wiring board 1. Then, the heat dissipation plate 5 and the conductive pattern (conductor circuit) 11 are soldered by melting the solder paste by a reflow process such as an infrared heating furnace and a vapor phase. After that, these assembled bodies are arranged in a predetermined cavity of a predetermined mold, and a sealing resin (epoxy resin, trade name; “MP-
7100 ", manufactured by Nitto Denko Corporation, is injected and manufactured. As described above, the electronic component mounting device is manufactured.

(3) Effects of the Embodiment In this device, the metal heat sink and the conductive pattern of the wiring board are electrically joined by the solder introduced into the through hole. Therefore, the adhesiveness between the mold resin portion and the heat dissipation plate is good, and the heat dissipation plate and the conductive pattern are firmly joined together. Also, since it has a through hole of an appropriate size,
Since sufficient solder fillets can be produced, sufficient bondability can be ensured, and the total area of the four through holes is about 1 to 10% of the surface of the heat dissipation plate, so heat dissipation is not impaired. Furthermore, since the four through holes are formed at symmetrical positions, the overall balance is good. Further, the solder for joining the heat sink and the conductive pattern is Sn: Pb = 9:
It has a heat resistance of 1. Therefore, when the package is mounted on the motherboard in a later process, Sn: Pb = 6:
4: 1 (melting point; approx. 180 ° C), 9: 1
The solder part is difficult to remelt. Even if they are re-melted, the metal radiator plate and the conductive pattern are bonded to each other, so that they are less likely to be separated from each other. However, in the past, since the resin portion and the solder portion are joined together, the re-melting of the solder portion results in separation of the two.

The present invention is not limited to the specific examples described above, and various modifications may be made within the scope of the present invention according to the purpose and application. That is,
The number of through holes provided in the heat dissipation plate is not particularly limited, and may be one or two or more. However, in consideration of the balance of electric characteristics, it is preferable to use two or four with symmetry. The shape of the through hole is not limited to a circle, but an ellipse, a quadrangle (FIG. 3), a triangle,
Groove shape (whether a short groove or a long groove or the like is not necessary (FIG. 3), a linear shape, an L-shape or a curved shape, etc. may be used, and the number and arrangement method thereof are not particularly limited. ], And those similar to these may be used. The shape of the inner peripheral surface of the through hole is usually cylindrical, but is not particularly limited to this and may be any shape that penetrates.

Further, as shown in FIG. 4, the metal heat sink 5
A heat dissipation plate may be formed on one surface side (upper surface side in the figure) of which a groove portion 52 is formed which is connected to the through hole 51d and whose both ends are open. In this case, as shown in FIG. 5, the mold resin is filled in the groove 52 and the through holes 51d, 51d. The direction of the groove 52 shown in FIG. 4 is the direction in which the mold resin flows, and the resin 82 is filled into the groove 52 and the through hole 15d without resistance. In this case, since the solder portion 7 is covered with the mold resin 82, the solder portion is less likely to deteriorate (corrosion or the like), and therefore the connection reliability and the package reliability are further improved. As shown by the dotted line in FIG. 5, the surface of the heat sink may be thinly covered with resin.

The position of the through hole of the heat sink 5 is not particularly limited as long as it has a conductive pattern (conductor circuit) below. Further, the conductive pattern may be provided under a part of the through holes instead of all the through holes. Also, as shown in FIG.
The heat dissipation plate 5 may be provided with a protrusion 53 that is inserted into the through hole 12 for housing an electronic component. In this case, as shown in the figure, the electronic component that is adhesively fixed onto the protrusion 53 may be sufficiently housed in the through hole 12 or may protrude from the through hole 12.

[0022]

The electronic component mounting apparatus of the present invention is superior in the reliability of electrical connection and less deteriorated as compared with the case of the conductive adhesive, and the adhesion between the mold resin portion and the heat dissipation plate is good. .

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an electronic component mounting apparatus according to an embodiment.

FIG. 2 is a perspective view of a heat dissipation plate used in the electronic component mounting apparatus shown in FIG.

FIG. 3 is a perspective view of a heat dissipation plate having a rectangular through hole.

FIG. 4 is a perspective view of a heat dissipation plate having a round through hole and a groove portion connecting the through holes.

5 is a longitudinal sectional view of an essential part of an electronic component mounting apparatus using the heat dissipation plate shown in FIG.

FIG. 6 is a longitudinal sectional view of an essential part of an electronic component mounting apparatus using a heat dissipation plate having a protrusion.

FIG. 7 is a partial vertical cross-sectional view of an electronic component mounting apparatus in which solder is placed on the side wall of the heat sink to bond the heat sink and the conductive pattern.

FIG. 8 is a partial vertical cross-sectional view of an electronic component mounting apparatus in which a heat dissipation plate and a conductive pattern are joined with a conductive adhesive.

FIG. 9 is a partial vertical cross-sectional view of an electronic component mounting apparatus in which solder is arranged on the bottom of the side wall of the heat dissipation plate to bond the heat dissipation plate and the conductive pattern, and the surface is covered with a resin layer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Electronic component, 11; Conductive pattern, 12; Through hole for storing electronic component, 2; Electronic component (semiconductor chip), 3; Bonding wire, 4; Lead frame, 41; Inner lead part, 42; Outer lead part, 5; heat sink, 5
1; Through hole, 61, 62; Adhesive (adhesive layer), 7; Solder part, 8; Mold resin sealing part.

Claims (3)

[Claims] 1. A wiring board having a conductive pattern formed on at least the surface thereof and having a through hole for storing an electronic component, and fixed by an adhesive on one surface of the wiring board so as to cover the through hole for storing an electronic component. A metal heat sink, an electronic component mounted in the electronic component storage through hole and on the metal heat sink, and at one end of the conductive pattern electrically connected to the electronic component. In an electronic component mounting device comprising a plurality of lead frames connected to each other, the electronic component, the wiring board, a side wall portion of the metal heat sink and a mold resin sealing portion for sealing the inner lead portion of the lead frame. A through hole is formed in the metal heat sink, and solder is arranged in the through hole to electrically connect the conductive pattern on the wiring board to the metal heat sink. Electronic component mounting apparatus characterized by. 2. A wiring board having a conductive pattern formed on at least a surface thereof and having a through hole for storing electronic parts, and being fixed on one surface of the wiring board with an adhesive and being inserted into the through hole for storing electronic parts. A heat sink made of metal, an electronic component mounted on the protrusion of the metal heat sink, and one end of the conductive pattern electrically connected to the electronic component. Multiple lead frames,
In an electronic component mounting apparatus comprising the electronic component, the wiring board, a side wall portion of the metal heat sink and a mold resin sealing portion for sealing the inner lead portion of the lead frame, the metal heat sink is penetrated. A hole is formed, solder is arranged in the through hole, and the conductive pattern on the wiring board and the metal heat dissipation plate are electrically connected by the solder, the electronic component mounting apparatus. . 3. A groove portion, which is connected to the through hole and is open at both ends, is formed on one surface side of the metal heat radiating plate, and the mold resin is provided in the groove portion and the through hole. The electronic component mounting apparatus according to claim 1, which is filled.