JPS61288495A - Manufacture of 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 [Field of Industrial Application] The present invention relates to a method for manufacturing a multilayer circuit board.

[Conventional technology]

In a multilayer circuit board in which multiple wiring layers are provided on a metal substrate such as aluminum with insulating layers interposed therebetween, one method for establishing electrical conduction between the wiring layers is by using so-called through holes.

That is, as shown in Fig. 4, a copper foil (11 (1 m) is laminated on both sides of an aluminum substrate O1, in which through holes (!l) have been formed in advance, via an insulating layer (ta all), and then the through holes are (Drill a through hole (14) through the copper foil at the part 111 (C in the same figure), and then form a metal plating layer inside the through hole by chemical plating or electrolytic plating, and fill it with copper paste etc. to make it conductive. As another method, as shown in FIG. 5, an insulating layer (
A conductive paste (11 (11...) is printed and laminated in a desired pattern via an insulating layer (1) (la...), and the conductive paste connects each circuit at a predetermined portion. There are some that are designed to conduct.

[Problem that the invention seeks to solve]

Each of the above-mentioned methods has its own features, but (i) the above-mentioned through-hole method achieves the original aim of using a metal substrate such as an aluminum plate, namely, its excellent heat dissipation, workability, and rigidity. For example, there is a risk of damage due to the installation of through holes on the board, the presence of double-sided insulating layers, etc., and it will be difficult to install leadless IC components, which are expected to become mainstream in the future, if solder printing is not legal. In the printed lamination method, since a resin binder is used as the conductive material, the conductivity is generally low and soldering is difficult. There were problems such as the possibility that the wet processing at the time could destabilize product quality.

[Means for solving the mamyo point]

The inventors have completed this invention as a result of intensive studies to solve these problems.

That is, the present invention provides a multilayer circuit board in which two or more conductive wiring layers are provided on an insulating layer provided on a metal substrate such as aluminum or iron, with the insulating layer interposed therebetween. This is done by laminating metal foil or patterning the wiring by a desired method, and then holes are made at desired positions in the resulting multilayer wiring layer, starting from the top and ending at the lowest wiring layer, and the chain holes are filled with conductors or plated. This method of manufacturing a multilayer circuit board is characterized in that conduction between each wiring layer is achieved by depositing a conductor layer using the above method or by using both of these methods in combination.

[For production]

In this invention, two or more wiring layers are provided on a metal substrate, a hole is made from the top layer to the bottom layer, and a conductor is filled in the chain hole to provide interlayer conduction.
The heat dissipation properties, rigidity, etc. inherent to the metal substrate are not impaired.

In addition, solderability is maintained, and quality instability is hardly caused.

〔Example〕

The present invention will be explained in detail below with reference to the drawings.

In FIG. 1(a), (1) is a metal substrate made of aluminum or the like, and a first steel foil wiring layer (3a) and a second insulating layer (2a) are formed on the upper surface of the substrate via a first insulating layer (2a). A second copper foil wiring layer (3b) is laminated via a conventional method.

Next, as shown in FIG. 1 (bl), the first wiring layer (2a)
Drill a precision hole of the desired diameter from the top until it reaches hole (4).
form.

This hole (4) is actually formed using an end mill or router.
A hole (4) terminating in the first wiring layer (2a) described above is obtained using a drill or a laser beam in the following manner.

In other words, use an NC drill machine, (i) apply a weak voltage between the first wiring layer (3b) and the drill, and drill the hole by adjusting the descending amount of the drill starting from the point of contact between the two. The depth of the hole is determined by controlling with an NC device. (ii) The first wiring layer (3) is
The height of a) is stored in the NC device of the drill body, and the depth of the hole is determined by controlling the descending stop point of the drill using this stored amount. Next, as shown in Figure 1 (el), the height of the chain hole (4 ) to the metal conductor (5
) is embedded or a conductor is attached by plating to make the rewriting layers (3a) and (3b) conductive.

FIG. 2 shows another embodiment of the invention.

First, as shown in Figure 1a, drill a hole (6) slightly wider than the hole (6) in the substrate (1) at a position corresponding to the above-mentioned conduction hole.
6) Embed the insulating material (7) and finish it smooth with the substrate (1).

Next, in the same manner as in the above embodiment, two wiring layers are provided as shown in FIG. 3(b).

Then, a hole (4) is made in the same way, accurately positioned in the insulator buried portion (7), and a conductor (5) is filled in the hole to establish conduction between the rewriting layers (3a) and (3b).

In this method, the positional accuracy of the through hole is required to be quite high, but the depth is somewhat loose, and a drill other than the above-mentioned drill may be used as appropriate.

When a conductive paste is used as the above-mentioned conductor, air is removed and fired in a vacuum furnace as usual.

Alternatively, as shown in Figure 3, a hole is previously etched in the second wiring layer (3b) at the position where a via hole is required (Figure 3a), and then the center of the hole is aimed. Laser light (YAG laser - 0rCO2
It is also possible to form a hole that reaches the first wiring layer 3(a) using a laser (eg, laser), and then control its position by changing the amount of reflected light, etc. (FIG. 2(b)).

In both cases, the subsequent second layer pattern formation is carried out as usual.
Work such as etching resist and protection processing is performed to commercialize the product.

〔Effect of the invention〕

As is clear from the above description, the present invention provides a multilayer circuit board having two or more conductor wiring layers, in which the conductor wiring layers are formed by laminating metal foils or by patterning the wiring by a desired method. A hole is made from the upper wiring layer to the lowest wiring layer, and conduction between each wiring layer is achieved by burying a conductor in the chain hole, depositing a conductor layer by plating, or using a combination of both. The heat dissipation properties of the material are sufficiently maintained, the rigidity is not impaired, and there is little risk of deterioration of various properties of the product, so that the above-mentioned problems can be almost eliminated.

[Brief explanation of the drawing]

1, 2 and 3 are process diagrams of an embodiment of the method of the present invention, and FIGS. 4 and 5 are explanatory diagrams of a conventional method, respectively. 1... Board, 2m, 2b・=-absolute side L3 a, 3b-
Wiring layer, 4...hole, 5...conductor. Figure 1 Figure 2 Figure 3m Figure 4 Figure 5 Group only 1゜

Claims (1)

[Claims] When obtaining a multilayer circuit board in which two or more conductive wiring layers are provided on an insulating layer provided on a metal substrate such as aluminum or iron with an insulating layer in between, the formation of the conductive wiring layer is performed by laminating metal foils. Alternatively, wiring patterning may be performed by a desired method, and a hole may be formed at a desired position in the resulting multilayer wiring layer from the top to the bottom wiring layer, and a conductor may be embedded in the hole or a conductor layer may be attached by plating. Alternatively, a method for manufacturing a multilayer circuit board characterized in that conduction between each wiring layer is achieved by using both of these in combination.