JPS60136297A - Multilayer circuit 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 [Technical Field] The present invention relates to a multilayer wiring board used in electronic equipment and the like.

[Background technology]

Conventionally, printed wiring boards were mainly single-layer boards with conductor circuits on one or both sides, but in recent years, as LSIs have become more highly integrated and circuits have become faster, multiple printed wiring boards have been stacked on top of each other. Multilayer wiring boards have come into widespread use.

A multilayer wiring board consists of a laminated board with copper foil, etc. covered on one or both sides and a conductor circuit formed thereon, and a semi-cured adhesive sheet (prepreg) made of a paper or cloth base material impregnated with resin. ) are stacked alternately and pressure molded. For example, a typical four-layer circuit board includes an inner layer material with a conductor circuit formed on one or both sides of a copper foil-clad laminate, an adhesive material such as a resin liquid or semi-cured adhesive prepreg applied to the surface of the inner layer material, and It consists of three layers: copper foil or the outer layer of a single-sided copper foil-clad laminate with the copper foil-clad side facing outside.

As printed wiring boards and LSIs become denser and more highly integrated, an excessive amount of heat is accumulated on printed wiring boards due to the heat generated during element operation, which is one of the causes of malfunctions in LSIs and other devices. . For this reason, printed wiring boards with excellent heat resistance and thermal conductivity (heat dissipation) are sought after in order to reduce the temperature rise due to heat generation.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a high-volume wiring board with excellent thermal conductivity that prevents an excessive amount of heat from being stored in the wiring board.

[Disclosure of the invention]

In order to achieve the above object, the present invention has a metal foil-clad laminate with a conductor circuit pattern formed on one or both sides as an inner layer material, and a metal foil or a single-sided metal foil-clad laminate as an outer layer material. The gist of the multilayer wiring board is a multilayer wiring board characterized in that a sheet-like thermally conductive material having electrical insulation properties is interposed between an inner layer material and an outer layer material. That is, in this multilayer wiring board, a sheet-like thermally conductive material having electrical insulation properties is interposed between the inner layer material and the outer layer material, and thereby,
This is an attempt to dissipate the amount of heat accumulated in the multilayer wiring board and improve thermal conductivity.

The present invention will be explained in detail below.

FIG. 1 shows an embodiment of a multilayer wiring board according to the present invention, which is made of a polyimide laminate 1a as a base, an inner layer material 1 having conductor circuit patterns 1b formed on both sides thereof, and a copper foil. A sheet-like electrically insulating and thermally conductive material 3 is interposed between the outer layer material 2 and the outer layer material 2, with both surfaces thereof being sandwiched between adhesive prepregs 4. That is,
This multilayer wiring board uses the above materials 1 to 4 as constituent elements,
Polyimide adhesive prepreg 4, thermally conductive material sheet 3, adhesive prepreg 4 on the top and bottom of polyimide inner layer material 1,
The copper foils 2 are arranged in this order and are press-molded. The thermally conductive material sheet is prepared by spraying approximately 0.5 to 3% water onto thermally conductive material particles having a size of 3 μ to 15 μ, for example.
Pressurize at a high pressure of about 00 to 400 kg/Ca, and
It is sintered at a temperature of ~1500°C for 1 to 4 hours to form a film. The thickness of the sheet is preferably about 0.2 mm, but is not limited to this. The thicker the sheet, the more it contributes to heat dissipation, but even a sheet as thin as 0.1 mm can be sufficiently effective. Therefore, 0.1 mm to 1.0 m
The thickness can be arbitrarily selected within a thickness range of about m. If a plurality of sheets are used in one multilayer wiring board, the effect will be even greater, and the closer to the surface layer they are used, the higher the effect will be.

Sheets of thermally conductive materials can be used not only for multilayer wiring boards made of polyimide inner layer material and polyimide adhesive prepreg, but also for multilayer wiring boards made of epoxy resin, polyester resin, etc., and achieve similar effects. be able to.

As the thermally conductive substance, in addition to boron nitride, highly thermally conductive alumina, fused silica, etc. are used, and any of them can be formed into a sheet shape. Denka boron nitride GP (manufactured by Denki Kagaku Kogyo Co., Ltd.) is known as a commercially available boron nitride.

Examples will be described below.

(Example 1) The above four layers of polyimide inner layer material based on a polyimide laminate, polyimide adhesive prepreg, 0.1 mm thick boron nitride sheet, and copper foil were placed on the top and bottom of the inner layer material with adhesive prepreg and boron. Stack the nitride sheet, adhesive prepreg, and copper foil in this order, and then
Laminate molding was performed by heating and pressurizing for 90 minutes at 10° C. and 40 kg/crA to obtain a multilayer wiring board of an example.

When we measured the thermal conductivity of this multilayer wiring board, we found that
28.5 X 10', (cal 7cm, sec,
"C). This value is based on the thermal conductivity (6.2 x 10'
cal/cm, sec, about 5 times that of "C).

Furthermore, the multilayer wiring board according to the present invention has small dimensional changes and low dielectric constant.

(Example 2) Instead of the boron nitride sheet, alumina formed into a sheet was used as a thermally conductive material, arranged in the same layer configuration as in Example 1, and laminated and molded under the same conditions. 2 multilayer wiring boards were made.

The thermal conductivity of this multilayer wiring board using alumina as a thermally conductive material is 12.1 x 1 (1' cat /a
m.

sec, °C.

〔Effect of the invention〕

As described above, the multilayer wiring board according to the present invention has excellent thermal conductivity (or heat dissipation) because a sheet made of a thermally conductive material is interposed between the inner layer material and the outer layer material. There is. Therefore, it becomes possible to easily increase the density and multilayer the wiring board.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment according to the invention. 1a... Polyimide laminate board 1b... Conductor circuit pattern 1... Inner layer material 2... Outer layer material (copper foil) 3...
・Sheet of thermally conductive material 4...Polyimide prepreg agent Patent attorney Takehiko Matsumoto

Claims (1)

[Claims] fil A multilayer wiring board comprising a metal foil-clad laminate with a conductor circuit pattern formed on one or both sides as an inner layer material, and a metal foil or a single-sided metal foil-clad laminate as an outer layer material on the surface. A multilayer wiring board characterized in that a sheet-like thermally conductive material having electrical insulation properties is interposed between the inner layer material and the outer layer material. (2) The multilayer wiring board according to claim 1, wherein the thermally conductive substance having electrical insulation properties is at least one of boron nitride, alumina, and fused silica.