JPS589600B2 - Method for manufacturing high-density wiring boards using wires in the required wiring patterns - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-density wiring board using wires for necessary wiring patterns.

For general printed wiring boards, the subtract method, in which a copper-clad laminate is used and unnecessary parts are dissolved and removed using chemicals to form a wiring pattern, has become mainstream.

On the other hand, an additive method in which electroless plating is deposited on necessary parts using a non-copper-clad laminate is becoming popular.

In both of these methods, the wiring is formed on a plane, so it is not possible to cross the wiring on the same plane.For crossing wiring, different planes are used, a through hole is created between the plane areas, and the through hole is electroless plated. etc., to make interlayer connections.

To improve these shortcomings, we have created a wiring board (hereinafter referred to as "wiring board") in which an adhesive layer is provided on an insulating substrate, and the insulated wires are held in the adhesive layer, as a high-density wiring board suitable for high-mix, low-volume production. Abbreviated as multi-wire wiring board (Hitachi Chemical Co., Ltd. product name).

). A wiring board that uses wires for such necessary wiring patterns (multi-wire wiring board) is a wiring board that uses wires for the necessary wiring patterns (multi-wire wiring board). ) Sometimes, a thermosetting adhesive that maintains thermoplasticity is laminated or coated, and insulated wires (wires) covered with a heat-resistant resin such as polyimide resin are laid using a numerically controlled wiring machine and then pressed. The wire is manufactured by fixing the wiring wire with a wire, etc., opening a through hole across the wire at the end of the wire, exposing the cut end of the wire on the peripheral wall of the through hole, and forming an electroless metal layer on the inner wall of the through hole to connect with the cut end of the wire. There is.

Since the multi-wire wiring board uses insulating coated wires, it has high insulation even if the wirings intersect or are placed in parallel in close proximity, making it suitable for high-density wiring.

However, in this multi-wire wiring, when the wiring pitch becomes high density and dense to about 2 to 3 times the diameter of the insulated wire, it becomes difficult to hold the intersecting wires with the adhesive layer as shown in Figure 1. As a result, it can easily be torn off or cannot hold its position with sufficient accuracy.

In FIG. 1, 1 is an insulated wire, 2 is an adhesive layer, and 3 is an insulated substrate.

Additionally, there is a problem in maintaining adhesion between wires that are wired adjacently at high density.

As a high-density wiring board that solves these problems, there is a multilayer multi-wire wiring board that increases the number of wiring layers.
The wiring housed inside the wiring board cannot be seen with the naked eye from the surface because the adhesive layer is opaque, making inspection difficult and making changes to the wiring extremely difficult.

In order to conduct high-density wiring up to twice the diameter of the wire, it is necessary to have multiple wiring layers (wire is routed twice), and in order for the wiring to be visible with the naked eye, , a portion of the initially laid wire must be exposed through the opaque adhesive layer.

In order to simultaneously satisfy these two conditions, in the present invention,
After wiring the wire on the adhesive, a film adhesive thinner than the diameter of the wire was heated and pressed to cover the wiring surface, thereby forming the adhesive so that the top of the wire was exposed.

Next, further wiring (wiring) is performed, but at this time, the wiring positions must be as if they were laid on the same plane, and overlapping of the wiring must be avoided.

After wiring is completed, the wiring is fixed by heating and pressing using a transparent overlay.

FIG. 2 shows a cross-sectional view of a multi-wire wiring board produced by the method of the present invention, in which 1 is an insulated wire, 2 is an adhesive layer, 3 is an insulated substrate, and 4 is a second adhesive layer.

In a multi-wire wiring board manufactured by such a method, the wiring can be seen from the surface with the naked eye as if they were wired on the same plane, and the wiring is high-density and easy to inspect and change the wiring.

Example 1 Copper-clad glass-epoxy laminate (Hitachi Chemical Co., Ltd., trade name MCL-E-1 6 1) thickness: 1. A base substrate having a power layer on one side and a ground layer on the other side was prepared by etching a 6 mm thick layer using a conventional method.

Multi-wire adhesive prepreg HN is applied to this base board.
-05G (Hitachi Chemical Co., Ltd. product name) heated to a temperature of 15
Lamination and bonding were carried out by hot pressing at 0°C, pressure of 20 kg/cm2, and heating time of 10 minutes.

Next, insulated wires with a wire diameter of 0.14 mm were wired at a pitch of 0.508 mm using a multi-wire wiring machine.

This substrate was removed from the wiring machine, multi-wire adhesive HA-05 was applied onto the polypropylene film, and a dried film adhesive (thickness: 0.1 mm) was laminated and bonded under the above conditions.

On this board, wiring was further performed using a wiring machine at a pitch of 0.508 mm and with a position shift of 0.254 mm from the first wiring.

As a result, the total of the first and second wiring is 0.25
The pitch was 4mm, and high-density wiring was achieved.

Moreover, the wiring pattern could be visually confirmed even for the first wiring, making it easy to inspect and correct the wiring.

Example 2 1 Copper-clad glass-epoxy laminate MCL-E-168
(Product name of Hitachi Chemical Co., Ltd.) A base substrate having a thickness of 1.6 mm and having one side as a power layer and the other side as a ground layer was prepared by a conventional method.

Multi-wire adhesive prepreg HA is applied to this base substrate.
-05G with a thickness of 0.25 mm was laminated and bonded on both sides by hot pressing.

Next, insulated wires with a wire diameter of 0.10 mmφ were wired at a pitch of 0.406 com using a multi-wire wiring machine.

This substrate was removed from the wiring machine, multi-wire adhesive agent HA-05 was applied onto the polypropylene film, and a dried film adhesive (thickness: 0.06 mm) was laminated and bonded using a hot press.

On this board, wires with a deviation of 0.203 mm from the existing wires were added by 0.4
This was done at a pitch of 0.06 mm.

As a result, the total of the first and second wiring is 0.20.
With a pitch of 3mm, we were able to achieve high-density wiring.

All wiring patterns could be visually confirmed and inspection and wiring corrections possible.

As explained above, the following effects have been achieved in the present invention.

(1) By using two adhesive layers, the minimum wiring pitch can be halved compared to the conventional one, making it possible to pass three to four wires between IC terminals at a pitch of 2.54 mm.

This makes it possible to mount components at twice the density compared to conventional wiring boards.

(2) Since the wiring can be observed from the surface, it is easy to inspect and correct the wiring.

[BRIEF DESCRIPTION OF THE DRAWINGS] 1. The drawings show cross-sectional views of multi-wire wiring boards, with FIG. 1 showing the conventional one and FIG. 2 showing the one according to the present invention. Explanation of symbols, 1... Insulated wire, 2...
Adhesive layer, 3... Insulating substrate, 4... Second adhesive layer.

Claims (1)

[Claims] 1. It consists of forming an adhesive on an insulated substrate, placing an insulated wire on the adhesive, simultaneously adhering it to form a wiring pattern, drilling a through hole across the insulated wire, and metallizing the inside of the through hole. In the manufacturing method of wiring boards using wires for the required wiring pattern, after the insulated wires are laid on the adhesive and bonded at the same time, a second adhesive is applied so thick that the tops of the insulated wires are exposed. A high-density wiring board using wires for a necessary wiring pattern, characterized in that an insulated wire is further laid on top of a second adhesive and bonded at the same time to form a wiring pattern. Manufacturing method.