JPS59117290A - Flexible copper-lined printed printed 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 the Invention The present invention relates to a flexible copper-clad printed circuit board that can be used as a printed wiring board for electronic equipment.

Conventional configurations and their problems In recent years, the electronic equipment industry has been moving toward high-density mounting of high-power semiconductor components such as transistors on printed wiring boards, and in order to make them smaller, lighter, and thinner. It is required to use a printed circuit board with excellent thermal conductivity as a wiring board. In particular, as electronic devices become smaller, lighter, and thinner, flexible printed wiring boards with flexibility are being used as printed wiring boards for high-density mounting. Due to the trend toward higher density, there is a high demand for flexible copper-clad printed circuit boards with excellent thermal conductivity.

A conventional flexible copper-clad printed circuit board will be described below with reference to the drawings. Fig. 1 is a cross-sectional view of a flexible copper-clad printed circuit board with a conventional single-sided copper-clad structure, in which a printed circuit board copper foil 1 with a thickness of about 35 μm and a polyimide film substrate 2 with a thickness of 35 μm to 50 μm are bonded with resin. They are bonded together by pressure pressing using a laminator and heat aging via the agent 3, thereby forming a flexible copper-bonded printed circuit board with copper bonded on one side. FIG. 2 is a cross-sectional diagram of a conventional flexible copper-clad printed circuit board with steel on both sides, similar to FIG. 1. Center thickness 35μ
Copper foil 1' for a printed circuit board with a thickness of about 35 μm is bonded to both sides of a polyimide film substrate 2' with a thickness of m to 50 μm using a pressure press using a laminator and a heat aging method via a moe fat adhesive 3'. , consists of a double-sided steel printed circuit board.

The conventional flexible copper-bonded printed circuit board constructed as described above has the disadvantages that the adhesives 3 and 3' are made only of resin material, and that the substrate material is made of resin material such as polyimide film. When starting out as a flexible wiring board, there are limits to the direct mounting of semiconductors and printed resistors that require high power on the flexible wiring board in terms of thermal conductivity. Heat dissipation is a difficult problem.

OBJECTS OF THE INVENTION An object of the present invention is to provide a flexible copper-clad printed circuit board with improved thermal conductivity.

Structure of the Invention The flexible copper-clad printed circuit board of the present invention has at least two insulating layers formed on one surface of a silver foil base, at least one of which is a ceramic insulating layer. By interposing it, a flexible gold-plated printed circuit board with excellent heat conduction can be obtained.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figures 3 (8) and (B) are cross-sectional views showing the manufacturing process of a flexible copper-clad printed circuit board with one side copper-clad. First, conductor formation is performed by etching as shown in Figure 3 (8). Ceramics (for example, a water-soluble 1 bamboo-based paint manufactured by Nippan Research Institute, whose product name is Cerami-Ryoku) are made by using easy-to-use copper foil 4 for printed circuit boards, and the main ingredients are zirconia, silica, silicon nitride, silicon carbide, etc. A ceramic insulating layer 5 is formed by applying a super heat-resistant, corrosion-resistant ceramic coating agent, etc.

Next, as shown in FIG. 3(B), polyphenylene oxide, polysulfone,
A resin insulating layer 6 is coated with a paint made of a heat-resistant engineering plastic such as polyether sulfone, polyether ketone, polyamide-imide, or polyimide. As a result, a flexible copper-clad printed circuit board with copper on one side is obtained.

Next, FIGS. 4(8) and (B) are front views showing the manufacturing process of a flexible copper-clad printed circuit board based on a double-sided steel-clad structure. First, as shown in FIG. A ceramic insulating layer 8 is formed on the copper foil 7 for a printed circuit board, and then, as shown in FIG. A resin insulating layer 9 made of a similar heat-resistant engineering plastic is interposed and bonded.

Next, Figures 5 (8 to q) are cross-sectional views showing the manufacturing process of a flexible copper-clad printed circuit board with copper-clad structure on both sides of the tail, similar to Figure 4, but the differences from the embodiment shown in Figure 4 are as follows. The first point is that two ceramic insulating layers are provided, as shown in Fig. 5 [
Two printed circuit board copper foils 10, 10 as shown in
A ceramic insulating layer 11 and a ceramic insulating layer 11' are then formed on each layer 11 and 11' as shown in Fig. g5 (B).
, 11' facing inward is an adhesive sheet made of heat-resistant engineering plastic (which can be bonded by making adhesive into a sheet and hot pressing). As shown in FIG. 5 (q), they were bonded together by thermocompression.

Next, the structural features of the flexible copper-clad printed circuit boards of each embodiment configured as described above will be explained.

First, in order to improve thermal conductivity as a printed circuit board, a ceramic insulating layer is formed by coating a ceramic coating, and furthermore, in order to provide flexibility as a flexible copper-clad printed circuit board, the ceramic layer is A resin insulating layer is adhesively formed on at least one surface of the ceramic insulating layer, thereby eliminating the brittleness of the ceramic insulating layer. Further, as can be seen from the explanatory drawings of each of the above embodiments, the ceramic insulating layer is formed on the surface of the silver foil for the printed circuit board.

This is because the adhesion strength of the ceramic insulating layer is much greater when coating and adhering ceramic in the form of paint to the copper foil surface for the printed circuit board than when coating and adhering resin to the resin film surface. Rather than coating the surface of a hardened resin insulating layer, it is possible to form a ceramic insulating layer and then apply the resin as a coating. This is because the mutual adhesion strength is known to be higher when the artificial acid is used as a resin adhesive.

The thickness of the ceramic insulating layer required to construct the flexible steel-laminated printed circuit board of the present invention may be determined by the thickness of the ceramic coating agent, which is usually made of ceramic particles as thin as possible, but currently the maximum thickness is 6 μm to 1 mol. The situation is such that it is impossible to avoid the contamination of large diameter particles. In order to apply a ceramic coating agent containing this particle size and to produce a flexible copper-clad printed circuit board of the present invention with a smooth surface without bubbles or pinholes, the thickness of the ceramic insulating layer must be 5 μm or more. Requires. On the other hand, the thickness of the resin insulating layer is determined in relation to the thickness of the ceramic insulating layer, the flexibility of the flexible substrate, and the number of insulating layers.

Next, FIG. 6 shows a structure in which the thickness of the ceramic insulating layer 5 is 10 μm and the thickness of the resin insulating layer 6 is 40 μm in the flexible copper foil printed circuit board with the single-sided shell-bonded structure shown in FIG. 3(B). , a test piece board from which the copper foil 4 for printed circuit boards was removed by etching the entire surface, and a conventional flexible steel-clad printed circuit board with one side of copper cladding made of polyimide film with a thickness of 50 μm, in which the copper foil was removed by etching. Test heather substrates were prepared, and carbon/resin-based printed resistors were formed on the esonant surface of each substrate in a size of 3 μm square, and the heat dissipation characteristics were compared. FIG. 6 is a load-temperature characteristic diagram of the printed resistor at an ambient temperature of 20° C., in which a load was applied to the printed resistor and the temperature rise of the printed resistor was determined under each load condition.

As shown in the characteristic No. 13, the temperature of the printed resistor on the conventional single-sided flexible copper-clad printed circuit board increases by 80°C for a 1W load, whereas the temperature rise of the printed resistor on the conventional single-sided flexible copper-clad printed circuit board increases by 80°C for a 1W load. In this case, as shown in the characteristic No. 14, the temperature rise is only 2 degrees Celsius, and the temperature rise and fall can be caused by the Z dimension. This temperature rise can be reduced by increasing the thickness of the ceramic insulating layer, and it is possible to mount high-power printed resistors or high-power semiconductor elements such as transistors.

Effects of the Invention As is clear from the above explanation, the present invention provides a method in which at least two insulating layers are formed on one surface of a copper foil base for a printed circuit board, and at least one of the layers is made of a ceramic or other insulating layer. As a result, a flexible steel printed circuit board with thermal conductivity and flexibility can be obtained, and when used as a flexible wiring board, it has the excellent effect of being able to mount semiconductors and printed resistors that require high power. can get.

In addition, by coating the ceramic insulating layer with a thickness of 5 μm or more, it is possible to increase the thermal conductivity by p.
When producing a flexible steel-laminated printed circuit board, a smooth substrate without air bubbles can be obtained, and at the same time, a flexible steel-laminated printed circuit board without pinholes in the ceramic insulating layer can be manufactured.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views of a conventional flexible steel printed circuit board with one-sided body bonding and double-sided copper bonding; Figure 3 (8);
(B), Figure 4 (8), (B) and Figure 6 (8-p1
FIG. 6 is a cross-sectional view showing the manufacturing process of a flexible steel-laminated printed circuit board in each embodiment of the present invention, and FIG. 6 is a characteristic diagram of the flexible steel-laminated printed circuit board according to an embodiment of the present invention. 4, 7, 7', 10, 10'---Copper foil for mountain printed circuit board, 5, 8, 11.11'... Ceramic insulation layer, 6, 9.12... Resin insulation layer. Figure 1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) A flexible copper-bonded printed circuit board made by adhering two or more insulating layers consisting of a ceramic insulating layer and a flexible resin insulating layer to one side of an ice foil base. (2) A flexible copper-clad printed circuit board according to item (1) of Patent No. 1fl-1, in which the thickness of the ceramic insulating layer is 5 μm or more. (3) A flexible hook-attached printed circuit board formed by bonding two copper foil bases with two or more insulating layers interposed, each consisting of a ceramic insulating layer and a flexible resin insulating layer. (4) The flexible copper-clad printed circuit board according to claim (3), wherein the thickness of the ceramic insulating layer is 5 μm or more.