JPH0358551B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention improves heat dissipation from electronic components such as chip elements or semiconductor elements, and blocks moisture from entering the electronic components from the outside. The present invention relates to a highly reliable substrate board for mounting electronic components 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 directly mounted 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) to be described later is an example of a substrate when a semiconductor element is directly mounted on a printed wiring board, and a ceramic substrate or an organic resin substrate 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 semiconductor element mounting portion 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 mounted semiconductor elements, and are applied only to semiconductor elements with relatively low output, that is, semiconductor elements that generate little heat. When mounting high-output semiconductor elements, it is necessary to take measures such as providing heat dissipation fins. In particular, organic resin substrates have low thermal conductivity and extremely poor heat dissipation from semiconductor elements. On the other hand, even on ceramic substrates such as alumina, when recent highly integrated high output semiconductor elements are mounted, the heat dissipation properties are insufficient. In addition, the problem with organic resin substrates as semiconductor mounting substrates is that their moisture resistance is very low compared to ceramic substrates.
In organic resin printed wiring boards with a structure like this, moisture from the outside penetrates the board and reaches the semiconductor elements, corroding the semiconductor elements, so this field requires high reliability in terms of moisture resistance. Therefore, it is difficult to use an organic resin substrate as a semiconductor mounting substrate.

[Means to be solved by the invention and their effects]

The present invention aims to simultaneously improve heat dissipation and moisture resistance, which are the drawbacks of the conventional printed wiring boards.
The inside of the printed wiring board has a metal coating, and the front side of the board is formed with a recess on which electronic components are to be mounted.The metal plate attached to the back side of the board is exposed on the bottom of the recess, and the side wall surface of the recess is exposed. The present invention provides a substrate for mounting electronic components in which a metal coating inside the substrate is exposed, and then a metal plate and a metal coating are integrated into a recessed portion by a metal plating coating.

When an electronic component such as a semiconductor element is mounted in the recess of the substrate, heat generated from the electronic component is efficiently and reliably diffused to the outside of the substrate via the metal plate and the inner metal coating.

Furthermore, the metal coating inside the board and the metal plate are integrated by the metal plating coating inside the recess, completely preventing moisture from entering from outside through the printed wiring board.

In addition, since the metal plate is installed in the recess on the back of the board, there is almost no increase in the overall thickness of the board.
It is also possible to make the substrate thinner.

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.

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

First, for convenience, the method of manufacturing a substrate for mounting electronic components according to the present invention will be explained with reference to the steps shown in FIG.

FIG. 2a shows a board 5 in which a printed wiring board 2 made of another organic resin material is laminated on at least the metal coating surface A of a printed wiring board 1 made of an organic resin material via an adhesive layer B. FIG.

Typical printed wiring boards include glass fiber-reinforced epoxy resin boards, paper phenol resin boards, paper epoxy resin boards, glass polyimide resin boards, and glass triazine resin boards. A metal coating such as copper foil is previously formed on one or both sides of these substrates. The adhesive layer is an uncured epoxy resin-impregnated glass cloth, a heat-resistant adhesive sheet, a liquid resin, etc.
Adhesive layers with high adhesiveness, heat resistance, durability, and other properties are preferred.

Next, FIG. 2b shows a multilayer board 5 in which a counterbore process is applied to the surface of the multilayer board 5 opposite to the part on which electronic components are to be mounted, and a recess 6 is formed so that the inner layer metal coating A is not exposed. FIG. Alternatively, after forming the recess 6 in the printed wiring board 1, the printed wiring board 2 may be laminated. FIG. 2c is a longitudinal cross-sectional view of the metal plate 7 bonded to the inner bottom surface of the recess 6 via the adhesive layer 4. The metal plate preferably has a relatively high thermal conductivity, such as copper, copper alloy, iron, iron alloy, aluminum, aluminum alloy, or the like. Although the size and thickness of the metal plate are not particularly limited, a thicker plate and a larger surface area are 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 deform the planar shape of the recess 6 on the back side of the board at least in two places, the sides or corners, and In Figures c and d, at least two sides or corners of the planar shape of the metal plate 7 are deformed, and it is advantageous to use these deformed parts to determine the mounting position of the metal plate. d in FIG. 2 is such that the metal plate 7 is exposed on the bottom surface at the location where electronic components are to be mounted from the opposite side of the back surface of the substrate where the recess 6 is formed, and the metal coating A is exposed on the side wall surface. FIG. 3 is a longitudinal cross-sectional view of a state in which a recessed portion 8 is formed by counterboring the laminated substrate 5. FIG. e in FIG. 2 is the recessed portion 8.
FIG. 2 is a cross-sectional view of a state in which a metal plating film 9 is formed on both surfaces of the laminated substrate including at least the inside. Examples of metal plating films include copper, nickel, gold, and tin. Due to the metal plating, the metal plate 7 and the metal coating A on the bottom surface of the recess are completely integrated.

FIG. 1 is a cross-sectional view of the electronic component mounting board of the present invention, in which a circuit is formed on the surface of the board by a conventional method. Fig. 2 f shows the semiconductor element 12 being die-bonded into the recess of the electronic component mounting board of the present invention, and the circuit of the semiconductor element and the board being connected with gold wire 13, and then the periphery of the semiconductor element is surrounded by epoxy resin 1.
4 is a sectional view of the sealed state. In this figure, reference numeral 11 is a frame for preventing outflow of epoxy resin, which is a laminated plate made of organic resin. Since the heat generated from the semiconductor element is dissipated in large quantities and reliably into the atmosphere through the metal plate 7 and the metal plating film A,
Compared to conventional printed wiring boards, it is possible to mount high-output semiconductor elements, and in the recessed part for mounting electronic components, the metal plating film 9 and the copper plate 7 are completely integrated. Since it is extremely rare for external moisture to reach the semiconductor element through the substrate, the life of the semiconductor element is significantly improved.

FIG. 4 is a perspective view of a pin grid array substrate according to the present invention. This is a pin grid array in which a large number of conductor pins 16 are arranged in a circumferential row in through holes 15 provided on the outer periphery of the electronic component mounting board. A thermosetting resin sheet 17 is attached to the outer periphery of the substrate and the surface of the through hole 15 shown in a perspective part 17 . This is to completely cover the through holes.

〔Effect of the invention〕

As described above, since 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, heat does not accumulate on the board, and heat does not pass through the board to the mounted electronic components. The circuit board has the characteristic that there is very little intrusion of external moisture, and the life of electronic components mounted on the circuit board is significantly extended.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a printed wiring board of the present invention, FIG. 2 is a longitudinal sectional view of the printed wiring board showing a flow sheet of the method for manufacturing the printed wiring board of the invention, and
FIG. 4 is a perspective view of a plug-in package board of the present invention, and FIG. 5 is a diagram of a conventional board for mounting electronic components. FIG. A...metal coating, b...adhesive layer, c...board surface on electronic component mounting side, d...bottom outer surface of metal plate mounting recess, 1, 2...printed wiring board, 4
... Adhesive layer, 5 ... Laminated board, 6 ... Recess (recess for mounting metal plate), 7 ... Metal plate, 8 ... Recess (recess for mounting electronic components), 9 ... Metal plating film, 1
0... Solder resist mask, 11... Resin sealing frame, 12... Semiconductor element, 13... Bonding wire, 14... Sealing resin, 15... Through hole, 16... Conductor pin, 17... Thermosetting Resin sheet.

Claims (1)

[Scope of Claims] 1 (a) A printed wiring board 1 made of an organic resin material having a metal coating A on at least one side, with another organic resin material placed on the metal coating A via an adhesive layer B. (b) In the laminate 5, counterboring is performed on the surface opposite to the mounting surface area for electronic components, and the inner layer metal coating is removed. (c) attaching the metal plate 7 to the bottom surface of the substrate in the recess 6 via the adhesive layer 4; (d) attaching the metal plate to the substrate; The base material on the opposite side of the surface is cut by counterboring,
A part of the metal coating A is exposed on the cutting side wall surface,
(e) forming a metal plating film 9 on the surface of the substrate including at least the inside of the recess 8, and forming a metal plating film 9 in the recess 8 and the metal plate 7; A method for manufacturing a substrate for mounting electronic components, which comprises a step of integrating with a metal plating film 9, and (f) a step of forming a circuit by a conventional method on the substrate manufactured through the above steps. 2. A metal plate 7 is mounted through an adhesive layer 4 in a recess 6 on the back side of a printed wiring board made of an organic resin material having a metal coating on the inner layer, and the upper surface of the board is used for mounting electronic components. In an electronic component mounting board in which a recess 8 is formed, the metal plate 7 is exposed on the bottom surface of the recess, and the inner layer metal coating A is exposed on the side wall surface of the recess: Inner layer of the electronic component mounting board A metal coating (A), which is a smooth surface substantially parallel to the substrate surface, is formed on the substrate surface (C) on the electronic component mounting side and on both side surfaces of the metal plate (7) on the electronic component mounting side. The metal plate 7 and the metal plating film 9 are bonded to form the bottom surface of the electronic component mounting recess 8, and the metal plate 7 and the inner layer of the substrate are located between the bottom outer surface of the recess 6. A substrate for mounting an electronic component, characterized in that one end surface of the metal coating A is joined in a perpendicular state to form a side wall surface of a recess 8 for mounting an electronic component. 3. Claims characterized in that the planar shape of the recess 6 on the back side of the laminated substrate 5 is deformed at at least two sides or corner parts to form alignment parts for metal attachment. The electronic component mounting board according to item 2. 4. The planar shape of the metal plate 7 is deformed at at least two sides or corners to form alignment parts for mounting the metal plate, as set forth in claim 2. Board for mounting electronic components. 5 Hole 15 provided on the outer periphery of the laminated substrate 5
3. The electronic component mounting board according to claim 2, wherein the electronic component mounting board is a pin grid array board in which a large number of conductor pins 16 are provided in a circumferential row. 6. The electronic component mounting board according to claim 2, wherein a thermosetting resin sheet 17 is adhered to the outer peripheral portion of the board and the surface of the hole 15.