JP2009064887A - Printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-based-substrate-type printed wiring board capable of improving a heat dissipation property by arranging a metal bump as an interlayer connection, and constantly holding and serving a highly reliable function. <P>SOLUTION: The printed wiring board includes a printed wiring layer arranged on a heat conductive resin layer 12 formed on at leat one surface of a heat conductive metal thin plate and the heat conductive resin layer connected by the metal bump inserted in an insulating layer formed on the heat conductive resin layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printed wiring board excellent in heat dissipation, and relates to an improvement of a metal base type printed wiring board.

  2. Description of the Related Art A printed wiring board that uses a thin metal plate as a base substrate has been developed in the configuration of a printed wiring board for the purpose of stabilizing the operation of a circuit device by imparting heat dissipation to the printed wiring board. FIG. 3 shows a cross-sectional view of the main configuration of such a metal-based printed wiring board. In FIG. 3, 1 is a metal base plate, 2 is an insulator layer, and 3 is a conductor (wiring) pattern. Here, the metal base plate 1 is a support / reinforcing body and functions as a heat radiating body.

For the purpose of improving the heat dissipation of a metal-based printed wiring board, Patent Document 1 discloses a conductive metal thin plate, a wiring pattern layer disposed on the surface of the conductive metal thin plate via an insulator layer, and the wiring. A printed wiring board comprising an interlayer connection portion for connecting a pattern layer and a conductive metal thin plate through an insulator layer, wherein the interlayer connection portion is at least one of a conductive metal thin plate surface and a wiring pattern layer surface The printed circuit board is formed on the surface of the metal plate, penetrates the insulator layer at the stage of pressure integration, and is plastically deformed and connected to the opposing conductive metal sheet surface side or wiring pattern layer surface side. Wiring boards have been proposed.
JP-A-7-86711

  However, since the printed wiring board uses a conductive paste using an organic polymer having low thermal conductivity for the interlayer connection portion, heat dissipation is not sufficient.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a printed wiring board that improves heat dissipation by disposing metal bumps as an interlayer connection in a metal base substrate type printed wiring board. To do.

  The printed wiring board according to the present invention includes a printed wiring layer disposed on a heat conductive resin layer formed on at least one surface of a heat conductive metal thin plate via an insulator layer, and the heat conductive resin layer. Are connected by metal bumps formed on the heat conductive resin layer and inserted through the insulator layer.

  As described above, in the printed wiring board according to the present invention, the electrical connection between the wiring pattern layers, the thermal connection with the heat conductive thin metal plate forming the wiring pattern and the ground layer, the heat dissipation layer, etc. This is achieved by inserting the metal bumps having excellent thermal conductivity into the insulator layer and connecting the opposing thermal conductive resin layer and the wiring pattern layer surface side. In this way, by using metal bumps with excellent thermal conductivity, heat dissipation can be improved, so that the mounting area surface and the wiring surface can be easily secured, and the printed wiring board is reliable. Maintains and demonstrates high functionality at all times.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 is a cross-sectional view of a main part of a configuration example of a printed wiring board according to the present invention. The formed heat conductive resin layer, 13 is an insulator layer formed on the surface of the heat conductive resin layer 12, and 14 is a wiring pattern formed on the surface of the insulator layer 13. Reference numeral 15 denotes an interlayer connection portion, which connects the wiring pattern 14 and the heat conductive resin layer 13 through the insulator layer 13. The present invention is characterized in that in the configuration of such a printed wiring board, the interlayer connection portion 15 forms bumps made of metal having excellent thermal conductivity.

  The printed wiring board according to the present invention can be generally manufactured by the following means. First, as the heat conductive thin metal plate 11, for example, an aluminum plate having a thickness of 1.5 mm is prepared. A high thermal conductivity epoxy resin adhesive (for example, R116-00 manufactured by Ryoden Kasei Co., Ltd.) is applied to the surface by a screen printing method to form an adhesive layer having a thickness of 15 μm. Next, an aluminum foil having a thickness of 50 μm is laminated on the adhesive layer, and thermocompression bonded, thereby manufacturing an aluminum-based metal plate in which the aluminum plate and the aluminum foil are integrated via the adhesive layer. Next, by subjecting the aluminum foil to a conventional photoetching process, bumps made of aluminum having a diameter of 0.3 mm and a height of 50 μm are formed on the thermally conductive adhesive layer at a pitch of 2.5 mm.

  Next, as an insulator, for example, an insulating resin film (trade name: ABF-70SH, manufactured by Ajinomoto Fine-Techno Co., Ltd.) made of an epoxy resin having a thickness of 70 μm is laminated on the bump and integrated by hot pressing. . Next, the aluminum bump is exposed to the surface by polishing the laminated insulating layer. Next, by performing electrolytic plating subsequent to conventional copper electroless plating on this surface, a 12 μm copper layer is formed on the epoxy resin layer with the aluminum bumps exposed on the surface, so that the required interlayer connection 15 A metal base substrate with a copper foil 16 provided with is manufactured (FIG. 2). Next, a required wiring pattern (14) is formed on the copper foil 16 of the metal base substrate with copper foil, thereby obtaining a printed wiring board having an interlayer connection portion 15 as shown in FIG.

  The printed wiring board was subjected to a hot oil test in order to check the connection reliability between the wiring pattern 14 and the heat conductive thin metal plate 11. Even after 500 cycles of cooling in 260 ° C oil for 15 seconds and 25 ° C for 15 seconds, no connection failure was observed.

  Moreover, the heat dissipation characteristics of the printed wiring board of the present invention were much better than the conventional printed wiring board in which bumps were formed with a conductive paste.

The principal part structure of the Example of the printed wiring board concerning this invention is shown in cross section. In the manufacture of an embodiment of the printed wiring board according to the present invention, a cross section of a configuration in which a copper layer is formed on an insulator layer with an aluminum bump exposed on the surface, and a metal base substrate with a copper foil provided with an interlayer connection portion FIG. The principal part structure of the conventional metal base type printed wiring board is shown in cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thermal conductive metal thin plate 2 ... Insulator layer 3 ... Wiring pattern 12 ... Thermal conductive resin layer 15 ... Interlayer connection part 16 ... Copper foil

Claims (1)

A printed wiring layer disposed on an insulating layer on a thermally conductive resin layer formed on at least one surface of the thermally conductive metal thin plate, and the thermally conductive resin layer are on the thermally conductive resin layer. A printed wiring board characterized in that the printed wiring board is connected by metal bumps formed on the insulator layer and inserted through the insulator layer.