JPH0744344B2 - Method for manufacturing multilayer printed circuit board with built-in metal core - Google Patents

Description

The present invention relates to a method for manufacturing a metal core-embedded multi-layer printed circuit board, wherein cracks are generated in a resin of a pressure-laminated prepreg in clearance holes of a metal core of the printed circuit board. In order to prevent the above, a prepreg formed by impregnating a glass nonwoven fabric with a material obtained by kneading a glass filler and a resin on both sides of a metal core having a clearance hole is laminated under pressure by heating and laminating the prepreg. It is composed by filling the material.

[Industrial application field]

The present invention relates to a method for manufacturing a metal core-embedded multilayer printed circuit board.

A printed circuit board containing a copper plate serving as a signal line or a power source, and a metal core built-in multilayer printed circuit board containing a copper plate to improve heat dissipation of the printed circuit board have been developed.

[Conventional technology]

A conventional multilayer printed circuit board with a built-in metal core is shown in FIG. 2 (a).
Thickness for signal line, power supply or heat dissipation as shown in
The copper plate 1A, 1B, 1C, 1D having a thickness of about 0.5 mm is perforated to form a clearance hole 2 so as not to be connected to a through hole formed in a later step, and further shown in FIG. 2 (b). So that the clearance hole has been processed into a copper plate 1
After laminating a prepreg 3 impregnated with epoxy resin on a glass nonwoven fabric woven with glass fibers on both sides of A, 1B, 1C, 1D, copper foil 4 is installed on the uppermost layer and the lowermost layer, and these copper plates 1, prepreg 3 and copper foil 4 are laminated under pressure and heat.

Next, as shown in FIG. 2 (c), through holes 5 are formed so as to penetrate through the printed circuit boards laminated under pressure and heat, and through-hole conductors 6 are formed in the through holes 5 by electroless copper plating and electrolytic copper plating. Then, a printed circuit board with a built-in metal core is formed.

[Problems to be Solved by the Invention]

By the way, the copper plate that will be the metal core of the printed circuit board 1
The thickness of A, 1B, 1C, 1D is about 0.5 mm, and when these copper plates 1A, 1B, 1C, 1D, the prepreg 3 and the copper foil 4 are pressure laminated, FIG. As shown in, the volume occupied by the resin extruded from the glass cloth under pressure from the prepreg in the clearance hole 2 is not 40% to 50 μm thin copper foil as the intermediate layer It is larger than the multi-layer printed circuit board.

Since the coefficient of thermal expansion of the resin that oozes out from the glass cloth of the prepreg at the time of this lamination is larger than the coefficient of thermal expansion of the copper plate 1, the printing at the time of soldering for mounting electronic components on the subsequent printed circuit board is performed. Due to the temperature difference between when the board is heated and when the printed circuit board is at room temperature, a difference in thermal expansion coefficient between the copper plate 1 and the resin causes a problem that cracks are generated inside the resin in the clearance hole 2. .

The present invention eliminates the above-mentioned problems, and when a metal core having a large thickness is used as in a metal core-embedded multi-layer printed circuit board, the resin in the clearance hole portion of the metal core is cracked. An object of the present invention is to provide a method for manufacturing a printed circuit board with a built-in multi-layered metal core, which is prevented.

[Means for Solving the Problems]

The method for producing a printed circuit board of the present invention to achieve the above object, a prepreg formed by impregnating a glass nonwoven fabric with a material obtained by kneading a glass filler and a resin is formed on both surfaces of a metal core by press-heating and laminating. It consists of.

[Action]

In the method for producing a printed circuit board of the present invention, a glass non-woven fabric is formed as a prepreg by impregnating a material obtained by kneading a glass filler and a thermosetting resin, and the prepreg is pressure-heated and laminated on both surfaces of a metal core having clearance holes. As a result, the clearance hole of the metal core can be easily and reliably filled with the material in which the glass filler and the thermosetting resin are kneaded.

Then, the value of the coefficient of thermal expansion of the mixture of the glass filler and the thermosetting resin exuded from the glass nonwoven fabric at the time of lamination,
The coefficient of thermal expansion is lower than the coefficient of thermal expansion of the resin itself, and is close to the coefficient of thermal expansion of the metal core.Therefore, the resin in the clearance hole part of the metal core during soldering work when mounting electronic components Less cracking.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a multi-layer printed circuit board with a built-in metal core according to the method of the present invention.

As shown in the figure, the clearance hole 11 is formed on both surfaces of the metal core 12 made of a copper plate having a thickness of about 0.5 mm, and the glass nonwoven fabric of the present invention is impregnated with a kneaded material of a glass filler and a thermosetting resin. The formed prepreg 13 is installed, the copper foil 14 is installed on the uppermost layer and the lowermost layer of these prepregs 13, and the metal core 12, the prepreg 13 and the copper foil 14 are laminated under heating and pressure to form a metal core built-in multilayer. A printed circuit board is formed.

This prepreg is manufactured by impregnating a glass non-woven fabric (glass filler is not woven in the form of glass paper) with a material obtained by kneading the glass filler with a thermosetting resin. There is. This glass filler is a crushed glass filament and has a diameter of 5 to 5.
It has a shape of 9 μm and an average length of 40 μm. The surface is chemically treated and treated with a silane coupling agent to improve adhesion with the resin.
Further, it is formed by using E glass which has a low dielectric constant and is called a unit E in the Jis standard.

Further, as in the conventional case, a glass woven cloth is used, and the reason why the glass nonwoven cloth is used instead of the prepreg in which the glass woven cloth is impregnated with the epoxy resin is that the glass filler is dispersed in the glass woven cloth during pressure lamination. This is because it is difficult to prevent the function of the filter that occurs when the glass woven fabric is used.

By doing so, the clearance hole 11 of the metal core
The resin in the part is a resin in which glass filler is mixed and dispersed, and its thermal expansion coefficient is close to that of the metal core 12.Therefore, the printed circuit board is heated at the time of soldering work when mounting components. Even if it is cooled to room temperature after that, cracks are less likely to occur in the clearance holes.

Since the glass filler is mixed and dispersed in the resin,
The mechanical strength of the printed circuit board formed is also improved.

〔The invention's effect〕

As is clear from the above description, according to the present invention, a highly reliable multi-layer printed circuit board with a built-in metal core, which does not cause thermal distortion in the clearance hole portion at the time of soldering work at the time of mounting electronic components, is obtained. It is effective.

[Brief description of drawings]

FIG. 1 is a sectional view of a printed circuit board of the present invention, and FIGS. 2 (a) to 2 (c) are explanatory views of a conventional printed circuit board manufacturing process. In the figure, 11 is a clearance hole, 12 is a metal core, 13 is a prepreg, and 14 is a copper foil.

Claims (1)

[Claims] 1. A metal core (1) having a clearance hole.
On both sides of 2), prepreg (13) formed by impregnating a glass nonwoven fabric with a material obtained by kneading glass filler and resin,
A method for manufacturing a multi-layer printed circuit board with a built-in metal core, comprising laminating under pressure and heating, and filling the kneading material into the clearance hole.