JPS61124196A - Multilayer wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a multilayer wiring board with excellent heat dissipation properties that can effectively dissipate Joule heat generated by an LSI during operation of components.

Conventional configurations and their problems In recent years, high-density wiring and high-density component mounting have been implemented on printed wiring boards, and a large number of LSIs have been placed in a limited space. The Joule heat generated is large, and this heat treatment has become a problem. As shown in Figure 1, in a conventional 2-base multilayer wiring board, the heat dissipation of the wiring board itself is poor, so the heat treatment method used is a method in which the cooling fins provided on the LSI are forcedly cooled by air cooling. I've been exposed to it. However, the above method has the disadvantage that heat cannot be sufficiently dissipated. on the one hand,
A metal core printed wiring board with excellent heat dissipation properties as shown in FIG. 2 has been developed. In this method, the surface of a thin aluminum plate 1 is coated with an insulating material 2 such as epoxy/polyimide resin or enamel, and a desired circuit 3 is placed on this surface.
and through holes 4 are formed by plating. However, in this wiring board, the area around the wiring board and the through hole swells, the surface smoothness is poor, and warping is likely to occur. In addition, the metal oxide constituting the enamel undergoes ionization and remaiplication due to the action of heat and electric field. Furthermore, metal core printed wiring boards have disadvantages such as the size of the wiring board being limited to small ones and making multilayering difficult. Therefore, it has been desired to develop a multilayer wiring board with excellent heat dissipation properties.

Page 3 Purpose of the Invention The present invention is intended to eliminate such conventional drawbacks, and is to provide a multilayer structure with excellent heat dissipation properties that can effectively dissipate the Joule heat generated in LSI and circuits during component operation. The present invention provides wiring boards.

Structure of the Invention In order to achieve the above object, the multilayer wiring board of the present invention comprises an outer layer copper foil forming a circuit and an inner layer copper foil connected via through holes, an inner layer steel foil used as a power supply circuit or a ground circuit. is exposed at the end of the wiring board, and a heat dissipation plate made of the exposed inner layer copper foil. With this configuration, by forcibly cooling the exposed inner layer copper foil, the Joule heat generated by the LSI and the circuit when the component is operated can be effectively dissipated.

DESCRIPTION OF EMBODIMENTS An example of the manufacturing method of the present invention will be described below with reference to the drawings. As shown in Figure 3, after forming the inner layer circuit used as a power supply circuit or ground circuit and the copper foil part used as a heat sink, the surface and side surfaces of the inner layer circuit are coated with a chemical to improve adhesion to the resin. Inner layer material 69 with target surface treatment
An adhesive 6 mainly composed of epoxy resin is applied to both sides, outer layer materials 7a and 7b having copper foil on one side are superimposed, and the adhesive 6 is cured by irradiating with an electron beam 8. A four-layer multilayer wiring board 9 as shown in the figure is formed. In this way, the four-layer multilayer wiring board 9 with the inner layer steel foil exposed at the ends of the wiring board can be easily formed. Figure 6 shows 4
This is a cross-sectional view of a multilayer wiring board in which a multilayer wiring board 9 has been subjected to hole processing, through holes 1o have been formed, and electroless plating 11 has been performed. FIG. 6 shows a cross-sectional view of the multilayer wiring board after the resist film 12 has been formed. Figure 7 shows
Electrolytic copper plating 13. This figure shows a cross section of a multilayer wiring board after electrical solder plating 14 has been performed and resist film 8 has been removed.

FIG. 8 is a sectional view of a multilayer wiring board on which multiple circuits were formed by etching, fusing was performed, and then solder printing 15 was performed. Figure 9 is a cross-sectional view of a multilayer printed wiring board with excellent heat dissipation, obtained by external processing to prevent short circuits between inner copper foil layers and to form a multilayer wiring board (see page 5). This shows that.

Although FIGS. 5 to 8 show an example of a four-layer multilayer wiring board 9, a multilayer wiring board with six or more layers can be formed in the same manner. The multilayer wiring board of the present invention obtained as described above is produced by forcibly cooling the exposed inner layer copper foil heat sink 16.
As shown in FIG. 10, the Joule heat generated by the LS 117 when the component operates is transmitted to the lead portion 18 of the LSI. Soldered through hole 19. The connection between the through hole and the inner layer copper foil used as a power supply circuit or ground circuit, and the inner layer copper foil used as a power supply circuit or ground circuit.

It is transmitted to the heat sink. In this way, the Joule heat generated by the LSI can be dissipated.

Although the heat sink is shown at only one location in FIG. 10, the heat dissipation performance is further improved by providing the heat sink at one or more locations.

Effects of the Invention As described on page 6 and above, the present invention provides an arrangement in which, of the inner layer copper foil connected to the outer layer copper foil forming the circuit through the through-hole, the inner layer copper foil used as the power supply circuit or the earth circuit is connected to the outer layer copper foil forming the circuit at the edge of the wiring board. By exposing the exposed inner layer copper foil and providing a heat dissipation plate, it is possible to effectively dissipate the Joule heat that is generated more often than in LSI when the component is operated, and its practical effect is great.

[Brief Description of the Drawings] Fig. 1 is a sectional view of a conventional four-layer multilayer wiring board, Fig. 2 is a sectional view of a conventional metal core printed wiring board, and Fig. 3 is a multilayer wiring in an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a method of laminating boards, FIG. 4 is a cross-sectional view of a four-layer multilayer wiring board according to the present invention, and FIGS. Figure 9 is a cross-sectional view of the same layer wiring board, and Figure 10 is
The figure is a cross-sectional view of the same multilayer wiring board on which an LSI is mounted. 7a, 7b...outer layer material, 1o...through hole, 16...heat sink. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
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Claims (1)

[Claims] Of the inner layer copper foil connected via through-holes to the outer layer copper foil that formed the circuit, the inner layer copper foil used as a power supply circuit or ground circuit is exposed at the edge of the wiring board, and this exposed inner layer copper foil is used as a heat sink. A multilayer wiring board characterized by its use.