JPH0420279B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves heat dissipation from electronic components such as chip devices or semiconductor devices, blocks moisture from entering the electronic components from the outside, The present invention also relates to a highly reliable electronic component mounting board that can be made thin and compact, and a method for manufacturing the same.

[Conventional technology]

BACKGROUND ART Conventionally, electronic components such as semiconductor elements are mounted directly on printed wiring boards, and boards electrically connected by wire bonding are used as interior boards for watches, cameras, and the like. A in the drawing (FIG. 5) shown later is an example of a board in which a semiconductor element is directly mounted on a printed wiring board, and a ceramic board or an organic resin board is used as the printed wiring board. . As shown in FIG. 5B, there is a printed wiring board in which a recess is formed on the surface of the substrate in a portion where a semiconductor element is mounted by counterbore processing or laminated molding, and a semiconductor element is mounted within the recess.

[Problem that the invention seeks to solve]

However, these conventional printed wiring boards do not provide sufficient heat dissipation for the heat generated by the semiconductor elements mounted on them, and are only applied to semiconductor elements with relatively low output, that is, semiconductor elements that generate little heat, and high output When mounting a semiconductor device, it is necessary to take measures such as providing heat dissipation fins. In particular, organic resin substrates have lower thermal conductivity than metals and are inferior in heat dissipation from semiconductor elements. On the other hand, even ceramic substrates such as alumina are insufficient for mounting recently highly integrated high output semiconductor devices. Also, the disadvantage of using organic resin substrates as semiconductor mounting substrates is that their moisture resistance is very low compared to ceramic substrates, as shown in Figure 5b.
In the case of an organic resin printed wiring board with a structure like this, high reliability is required in terms of moisture resistance because moisture from the outside can penetrate the board and reach the semiconductor elements, corroding the semiconductor elements. It is difficult to use organic resin substrates as semiconductor mounting substrates in such fields.

[Problem that the invention seeks to solve]

In order to improve heat dissipation and moisture resistance, which are the drawbacks of the conventional printed wiring board, the present invention provides a recess on the back side of the printed wiring board and a metal plate on the bottom of the recess via an adhesive layer. The present invention provides a substrate for mounting an electronic component, in which the electronic component is mounted, and a metal plating film is formed on the metal plate and both substrate surfaces. Therefore, the heat generated from electronic components such as semiconductor elements can be efficiently dissipated through the metal plate, and by attaching the metal plate to the recess of the printed wiring board, the entire board can be made thinner. be.

Furthermore, the metal plating film that coats the recess where electronic components are to be mounted and the area where the metal plate on the back side of the recess contacts the board prevents external moisture from penetrating through the adhesive layer and the board, allowing electronic components to be mounted. This can prevent water from entering the area. An object of the present invention is to provide a substrate for mounting electronic components, which has extremely excellent heat dissipation properties and moisture resistance, and which can be made thinner as described above, and a method for manufacturing the same.

[Means and actions to solve the problem]

The present invention will be specifically explained below based on the drawings.

First, the process of manufacturing a substrate for mounting electronic components according to the present invention as shown in FIG. 2 will be explained for convenience.

FIG. 2a is a longitudinal sectional view of the back side of the printed wiring board 1 in which a recess 9 is formed by counterboring. Typical printed wiring boards include glass fiber reinforced epoxy resin boards, paper phenol resin boards, paper epoxy resin boards, glass polyimide resin boards, glass triazine resin boards, and the like. Copper foil 2 is pre-coated on one or both sides of these boards.
Conductive films such as the above may be laminated and adhered. The size and depth of the recess formed on the back side of the substrate are not particularly limited. Next, b in Figure 2
1 is a longitudinal sectional view showing a metal plating film formed on the surface of the substrate 1 including at least the recess 9 on the back side of the substrate 1. FIG. The metal plating film 3 formed on the walls and bottom of the recess 9 is for preventing moisture from permeating. In FIG. 2c, a metal plate 6 is attached to the inner bottom surface of the recess a on the back side of the printed wiring board 1 via an adhesive layer 5.
FIG. The attachment layer may be an uncured epoxy resin-impregnated glass cloth, a heat-resistant adhesive sheet, or a liquid resin, and preferably an adhesive layer with high properties such as adhesiveness, heat resistance, and durability. On the other hand, metal plates are copper, copper alloy,
Any material with relatively high thermal conductivity, such as iron, iron alloy, aluminum, or aluminum alloy, may be used. The size and thickness of the metal plate are not particularly limited, but the thicker the plate and the larger the surface area, the better
This is advantageous in improving heat dissipation. As shown in FIG. 3 a and b, the method for determining the mounting position of the metal plate is to change the planar shape of the recess 9 on the back side of the board to a board whose sides or corners are deformed at least in two places. It is advantageous to determine the mounting position of the metal plate by deforming at least two sides or corners of the planar shape of the metal plate 6, as shown in c and d of FIG. 2d shows a state in which a recess 8 is formed by counterboring so that a part of the metal plate 6 is exposed at a location on the surface opposite to the back surface where the recess 9 is formed, where electronic components are to be mounted. FIG. FIG. 2e is a longitudinal cross-sectional view of a state in which the printed wiring board 1 and the metal plate 6 are integrated by forming a metal plating film 15 on both surfaces of the board including at least the recess 8. As shown in FIG. The metal plating film 15 has the effect of blocking water from entering the adhesive layer between the printed wiring board 1 and the metal plate 6 and preventing water from entering the electronic component mounting area. By being integrated with the metal plating film, the heat generated from the electronic components is quickly conducted from the metal plate to the copper foil and radiated to the outside, which has the advantage of improving the heat dissipation effect. FIG. 2f is a longitudinal cross-sectional view of a state in which a semiconductor element 12 is mounted on an electronic component mounting board according to the present invention, connected by wire bonding, and the semiconductor element and its surrounding area are sealed with resin 14. In this drawing, 14 is a sealing resin, such as epoxy resin or silicone resin. Also 7
is a weir frame for preventing the sealing resin from flowing out. The printed wiring board of the present invention manufactured in this manner has the characteristics shown in the longitudinal sectional view of FIG. The feature is that the surface side of the organic resin substrate 1 has a recess 8 on which a conductor circuit and electronic components are to be mounted.
The recess 8 has at least a metal plating film 15 in contact with the metal plate 6 on the back side, a recess 9 on the back side of the substrate 1, a metal plating film 3 on the surface of the recess, and a metal plating film 3 on the surface of the recess. A metal plate 6 is attached via an adhesive layer 5, and a metal plating film 15 is formed on the metal plate and both substrate surfaces. FIG. 4 is a perspective view of the plug-in package board of the present invention. This is the through hole 11 provided on the outer periphery of the electronic component mounting board.
This is a plug-in package in which a large number of conductor pins 10 are arranged in a circumferential row. A thermosetting resin sheet 16 is attached to the outer periphery of the substrate and the surface of the through hole 11 shown in the shaded area 16 . This is to completely cover the through holes.

〔Effect of the invention〕

As described above, the electronic component mounting board of the present invention has high heat dissipation properties even when electronic components that generate a large amount of heat are mounted, so that heat does not accumulate on the board, and external heat is not transmitted through the board to the mounted electronic components. Since there is almost no intrusion of moisture, the durability of electronic components is improved, and the printed wiring board after mounting can be made thinner.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a printed wiring board of the present invention, FIGS. 2 a to f are longitudinal cross-sectional views of the board showing a flow sheet of a method for manufacturing a printed wiring board of the present invention, and FIG. 3 is a longitudinal cross-sectional view of the printed wiring board of the present invention. FIG. 4 is a plan view of the substrate of the alignment section for attaching the metal plate to the substrate, FIG. 4 is a perspective view of the plug-in package substrate of the present invention, and FIG.
The figure is a vertical cross-sectional view of a conventional electronic component mounting board. DESCRIPTION OF SYMBOLS 1... Printed wiring board, 2... Copper foil, 3... Metal plating layer, 4... Solder resist mask, 5... Adhesive layer, 6... Metal plate, 7... Resin sealing frame, 8... Recess (recess for mounting electronic components) ), 9... recess (recess for attaching metal plate), 10... conductor pin, 11... through hole, 1
2... Semiconductor element, 13... Bonding wire,
14... Sealing resin, 15... Metal plating layer (second plating layer), 16... Thermosetting resin sheet.

Claims (1)

[Scope of Claims] 1. (a) forming a recess by counterboring on the back side of a printed wiring board made of an organic resin material, and (b) forming a metal plating coating on the surface of the substrate including at least the recess on the back side. (c) attaching a metal plate to the inner bottom surface of the recess via an adhesive layer; (d) attaching a metal plate to the surface opposite to the back surface on which the recess is to be mounted at a location where electronic components are to be mounted; A method for manufacturing a board for mounting an electronic component, comprising: forming a recess by counterboring so that a part of the metal plate is exposed; and (e) plating both substrate surfaces including at least the recess. 2. The manufacturing method according to claim 1, wherein the steps (a) to (e) are performed with a large number of electronic component mounting substrates arranged in a grid. 3. The manufacturing method according to claim 1 or 2, characterized in that a metal plating film is formed on the surface of the metal plate and the surface of the substrate at the same time. 4. The front side of the organic resin substrate has a recess on which a conductor circuit and electronic components are to be mounted, and the recess has at least a metal plating film in contact with the metal plate on the back side, and the organic resin substrate A recess is provided on the back side of the recess, a metal plating film is attached to the surface of the recess, and a metal plate is attached to the surface of the metal plating film via an adhesive layer, and a metal plating film is formed on the metal plate and both substrate surfaces. A board for mounting electronic components. 5. The planar shape of the concave portion on the back side is deformed at at least two sides or corner portions to form positioning portions for folding the metal plate, as set forth in claim 4. Board for mounting electronic components. 6. The electronic device according to claim 4, wherein the planar shape of the metal plate is deformed at at least two sides or corner portions to form positioning portions for mounting the metal plate. Board for mounting components. 7. The electronic component mounting board according to claim 4, which is a plug-in package board in which a large number of conductor pins are provided in a circumferential row in holes provided on the outer periphery of the board. . 8. The substrate according to claim 4, wherein a thermosetting resin sheet is adhered to the outer peripheral portion and the hole surface.