JPS62243397A - 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 the Invention The present invention relates to a printed circuit board having multilayer wiring.

Conventional technology A conventional multi-layer wiring board consists of forming a predetermined pattern of wiring on a copper foil conductor layer on an insulating substrate, coating a resin layer with openings on the wiring, and then coating the resin layer with conductive paint. A structure in which layers are formed and interlayer connections are made at the openings is known. Further, for this resin layer, an acid anhydride curing agent acid epoxy resin or a phosphate curing type melamine resin, which is suitable for printing and coating formation, has been used.

Problems to be Solved by the Invention In such a conventional structure, sufficient soldering strength to the conductive paint layer on the surface side cannot be obtained, resulting in low reliability in use. Furthermore, regarding the insulation properties of the resin layer, the withstand voltage characteristics were insufficient due to pinholes, impurity content, etc., and the resin layer lacked durability.

The present invention provides a multilayer wiring board that solves these problems.

Means for Solving the Problems The present invention has a first wiring layer with a predetermined pattern and a second wiring layer interposed between the flexible resin layer on an insulating substrate. This is a multi-wiring board in which the wiring layers are connected by a conductive paint layer through the openings of the flexible resin layer. The flexible resin layer is preferably made by impregnating Aramide fiber cloth with an epoxy resin containing an aromatic amine curing agent, and the second wiring layer is formed on the same resin layer by pressure bonding or aromatic adhesive. Those bonded by bonding with an amine hardening agent-containing epoxy resin are used.

According to the present invention, the first
A wiring resin layer having a second conductive layer on a flexible resin is laminated onto a wiring board having a conductive layer, and each of the first and second conductive layers is formed into a wiring pattern shape using a normal selective etching technique. None, and in the flexible resin existing between both conductive layers, a desired opening is formed using laser processing technology, and a conductive paint layer is further formed in the opening.
Since the through-hole connection is made between both conductive layers, high withstand voltage characteristics can be obtained, and the first and second
The conductive layer can be formed of copper foil, and soldering can be performed reliably.

Embodiment FIG. 1 is a cross-sectional view of a multilayer wiring board according to an embodiment of the present invention.
A first wiring layer 2 made of copper foil with a predetermined pattern on an insulating substrate 1
On top of this, a flexible resin layer 3 is formed, for example, by impregnating an aramid fiber cloth with a thickness of 0.025 to 0.1+nm with an epoxy resin containing an aromatic amine curing agent. Then, on this flexible resin layer 3, a second layer made of copper foil is formed.
The wiring layer 4 is laminated. The first wiring layer 2 made of copper foil and the second wiring layer 4 are connected by through-holes using a conductive paint layer 5 to achieve interlayer connection.

FIGS. 2a and 2b are cross-sectional views in the order of steps for forming a multilayer wiring board according to an embodiment of the present invention, and the manufacturing procedure thereof will be explained using these.

First, for the insulating substrate 1, a paper-based phenolic resin laminate, a paper-based epoxy resin laminate, a glass cloth-based epoxy resin laminate, or a glass cloth-based polyimide resin laminate is used, and on this, As shown in Figure 2 a, the thickness is approximately 0.03
A copper foil of 5m+n is arranged as the first wiring layer 2, and this first
The wiring layer 2 is formed into a predetermined wiring pattern by a well-known selective etching technique. Separately, a second wiring layer 4 made of copper foil with a thickness of about 0.035+mm is laminated on a flexible resin layer 3 made of a thin resin plate made of Aramide fiber cloth impregnated with an epoxy resin containing an aromatic amine hardener. This second wiring layer 4 is also prepared by forming a desired wiring pattern using a well-known selective etching technique. Then, these are stacked on top of each other, heated and pressurized, and bonded together as shown in Figure 2. The flexible resin layer 3 made of Aramide fiber cloth impregnated with an epoxy resin containing an aromatic amine curing agent has sufficient flexibility if it has a thickness of about 0.025 to 0.1 mm. Also, even if the same epoxy resin is already in a sufficiently cured state at the C stage, it is
Reheat to 0℃~170℃, 20~50kg/
cJ, when treated under pressurized conditions for 30 to 60 minutes, it adheres with good adhesion. When continuous pressurizing conditions cannot be obtained, the B stage cured state = 5- is applied to the back surface of the flexible resin layer 3 prepared in advance or the entire surface of the insulating substrate 1 having the first wiring layer 2. An epoxy resin layer containing an aromatic amine curing agent maintained at Processing may be performed.

Next, a desired opening 6 is formed in the flexible resin layer 3 using a so-called laser processing technique by laser beam irradiation. Aramid fiber cloth impregnated with an epoxy resin containing an aromatic amine curing agent does not show carbonization even when processed by laser, and a perfect opening can be achieved.

Then, by applying a silver powder-resin-based conductive paint to the opening 6 using, for example, a printing technique, and subjecting it to a predetermined curing treatment, for example, heat treatment at 145° C. for 30 minutes, the conductive paint shown in the first figure is coated. A paint layer 5 can be formed,
This allows through-hole connections between layers to be achieved.

The multilayer wiring board of this example was tested at 1,000M by pressure test (PCT) for 6 hours at 2 atmospheres.
It was confirmed that it maintains high insulation properties of Ω or more and has high voltage resistance.

Effects of the Invention According to the present invention, a first wiring layer on an insulating substrate and a wiring resin layer having a second wiring layer on a flexible resin are laminated and bonded together, and the flexible An opening is provided in the resin, and the conductive paint layer is applied through the opening to the first. Since both the second wiring layers are interlayer connected, the first wiring layer. Reliable soldering can be achieved for both second wiring layers, and the selection of the flexible resin, for example, a thin resin layer made of aramid fiber cloth impregnated with an epoxy resin containing an aromatic amine curing agent. By using this, it is possible to realize a multilayer wiring board with high insulation properties and high withstand voltage characteristics.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a multi-layer wiring board according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the steps of manufacturing the multi-layer wiring board according to an embodiment of the present invention. , 1... Insulating substrate, 2... First wiring layer, 3... Flexible resin layer, 4... Second
Wiring layer, 5... Conductive paint layer, 6... Opening.

Claims (2)

[Claims] (1) A second wiring layer is provided on an insulating substrate via a first wiring layer of a predetermined pattern and a flexible resin layer, and the flexible resin A multilayer wiring board with a conductive paint layer connected through the openings in the layers. (2) The multilayer wiring board according to claim 1, wherein the flexible resin layer is made of an epoxy resin containing an aromatic amine curing agent and containing Aramide fiber cloth.