JPS5857782A - Circuit board and method of producing same - 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 The present invention relates to a wiring board and a method for manufacturing the same, and more particularly, the present invention relates to a wiring board and a method for manufacturing the same, and more particularly, to a wiring board and a method for manufacturing the same, and more particularly, to fabricate a desired circuit pattern of insulated wires on an insulated substrate. The present invention relates to a wiring board that does not stick and a method of manufacturing the same.

In recent years, a conductor pattern such as copper foil is formed on an insulating substrate as necessary, and a desired circuit pattern of insulated wire is fixedly wired via an insulating adhesive layer (hereinafter referred to as the adhesive layer). After that, a through hole is drilled at a desired position, a metal conductor layer is formed on the wall of the through hole, and it is connected to the core wire of the insulated wire.A wiring board is used in which the butter 7 is electrically connected. It's starting to look like this.

Generally, this type of wiring board has the following characteristics. Since insulated wires are used as signal circuits, it is possible to intersect the signal circuits on the same plane, and patterns for two sides of a normal printed wiring board can be accommodated on one side. This eliminates the need for through holes, so-called via holes, for connecting the front and back sides. Furthermore, since via holes are not required, the number of channels that can be wired increases using the automatic needle method that determines wiring routes, allowing for higher wiring accommodation and higher packaging density. In addition, original circuit pattern drawings and photographs become unnecessary. In particular, if the circuit pattern needs to be changed, it is only necessary to partially change the take of the wire wiring frame for fixing the insulated wire, reducing the cost and time of recreating original drawings and photographs.

A typical example of this type of conventional wiring board will be described with reference to FIG. 1 and FIG. If necessary, on the insulating substrate containing the electroless plating catalyst as shown in Fig. 1(a),
For example, a patterned copper foil layer 2 is formed on one or both sides so that it can be used as a power supply layer or a ground island,
Next, as shown in FIG. 1(b), after forming an adhesive layer 3 containing an electroless plating catalyst in contact with the insulating substrate 1 and the copper foil layer 2, as shown in FIG. A desired circuit pattern of the transverse wire 4 is adhered to the adhesive layer 3 using, for example, a numerical IIJ type automatic wiring machine, and then the pattern shown in FIG.
In order to protect the circuit pattern formed by the insulated wire 4 fixed to the wiring as shown in d), and to ensure the fixation, a prepreg containing a catalyst for electroless plating is laminated and bonded to make it catalytic for electroless plating. An insulating layer 5 is formed. Furthermore, after forming a non-conforming mask layer (hereinafter referred to as a mask layer) 6 that does not have catalytic properties against electroless plating on the outer surface, insulated wires and copper are placed at desired positions as shown in FIG. 1(e). A through hole 7 is bored across the foil layer 2, and at least a portion of the insulated wire 4 and the copper foil layer 2 are patched onto the inner surface of the through hole 7, and then immersed in a no-solution plating solution. A metal conductor layer 8 was formed on the wall surface of the through hole 7 to form a through hole, and the mask 6 was removed as shown in FIG. 1 (0) to form a wiring board as shown in FIG. 2.

On the other hand, with the recent increase in the density of electronic devices such as ICs and LSIs, the wiring density required for wiring boards, that is, the number of wirings per unit area, is rapidly increasing. This is based on the idea that a through hole is drilled in a conventional wiring board, a conductive layer is plated on the hole wall, and the conductor patterns on the front and back sides are electrically connected. Therefore, it is necessary to switch to the idea of establishing electrical connections by providing micro-diameter holes at desired locations on the front and back surfaces, without making through connections. However, it has been extremely difficult to drill holes with a conventional hole diameter of, for example, 0.1 mm, using a conventional hole puncher due to the problem of drill breakage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new wiring board and a method for manufacturing the same, which eliminates the drawbacks of the conventional wiring board as described above.

According to the present invention, in a wiring board in which a desired circuit pattern of insulated composite wires is laid on an insulated substrate having a circuit pattern and an insulating resin layer is formed to cover the insulated wires, at least the insulated wires There is obtained a wiring board characterized in that a hole reaches the surface of the core conductor, and a conductor layer is provided on the inner wall surface of the hole and the surface of the core conductor. In addition, there are a step of depositing an insulating adhesive layer on the insulating substrate, a step of wiring and fixing the insulating coated wire on the insulating adhesive layer, a step of providing an insulating resin layer in which the insulated wire is multinucleated, and a step of providing the insulating resin layer with the insulating bonded wire. A process of forming a mismatched mask layer made of an insulator without catalytic properties by electroless plating on the surface of the layer, and a step of forming a mismatched mask layer and an insulating resin by irradiating a laser beam from above the mismatched mask layer. The process of providing a hole that penetrates a part of the layer to reach the conductor of the insulated wire is inconsistent with the process of forming a conductor layer by electroless plating on the inner wall surface of the hole and the conductor surface of the insulated wire. A method for manufacturing a wiring board is obtained, which comprises a step of removing a mask layer.

The present invention will be explained below with reference to FIGS. 3 and 4. FIG. 3 is a sectional view showing one embodiment of the present invention. Third
FIG. 1(a) shows the conventional example shown in FIGS.
This figure shows the state of a wiring board manufactured in an intermediate process in the same manner as in Figure (C). The upper and lower surfaces of a structure in which a desired number of prepregs having catalytic properties for electroless plating are stacked on both the front and back surfaces of a wiring board are held between flat plates (not shown) having sufficient rigidity and made of stainless steel, for example. , heat this plane.

Pressure is applied to form an insulating layer 5 having catalytic properties for electroless plating as shown in FIG. 3(b). Next, as shown in FIG. 3C, a mask layer 6 is formed in contact with the insulating layer 5 by, for example, thermocompression bonding. Next, as shown in FIG. 3(d), a laser beam is irradiated onto a desired position of the conductor of the insulated composite wire 4, and the mask layer 6 is
A hole 9 is provided that penetrates the insulating layer 5 and contacts the core conductor of the insulated wire 4, so that the core conductor of the insulated wire 4 is exposed. As a laser beam that can be used for this drilling process, a YAG laser is used in the first embodiment. The laser beam generator used in the example includes a laser beam generator 21 as shown in FIG. 4, an introduction path 22 for guiding the laser beam close to the workpiece 24, and an aperture adjustment for the laser beam. It consists of 23 items. For example, a YAG laser with an output of 50 W, which is oscillating continuously, is oscillated by using a Q switch for a frequency of 1 to 5 kHz, for example, by 0.1 to 1.
Pulsed light having a pulse width of milliseconds was irradiated to obtain the aforementioned hole 9 having an inner diameter of approximately 0108 mm. A carbon dioxide gas laser is available as a laser of the second embodiment that can be used for this drilling process. The configuration of this laser beam generator is basically the same as that shown in FIG. 4, and starts with a carbon dioxide gas laser with a continuous oscillation of, for example, an output of 60 W, with a period of 0.1 to 1 second and a pulse width of 0.1 to 1. Pulse light was irradiated for 50 seconds to obtain the same hole 9 as described above having an inner diameter of about 0.13 wam.

Next, the inside of the hole 9 is cleaned with a high-pressure water stream having a pressure of, for example, 30 to 90 kg/ffl to remove unnecessary foreign matter.

Furthermore, when the coating layer of the insulating coated wire 4 is made of polyimide resin, a hydroxide alkali such as sodium hydroxide is added to the water 11 at a temperature [40
The entire surface is immersed and shaken in a solution maintained at a temperature of ~70°C, preferably 50~60°C to clean the wall surface of the hole 9 and at the same time expose the inside of the hole 9 of the insulated composite wire 4. Remove all remaining coating material to completely expose the core conductor. Next, the entire surface of the wiring board is immersed and shaken in an electroless plating solution to form a plating film 10 on the wall surface of the hole, the exposed surface of the adhesive layer 30, and the surface of the core wire conductor from which the insulation coating has been removed. When the hole 9 is provided at the intersection of the insulated wires 4, the respective core wire conductors are electrically connected through the plating film 10 at the intersection. Next, as shown in FIG. 3(e), the unnecessary mask layer 6 is removed, for example, by mechanically peeling it off.

As described above, according to the present invention, the wiring density can be significantly improved by providing separate tactile electrical connection holes on the front and back surfaces of the wiring board without drilling through holes in the wiring board.

Furthermore, since the electrical connection hole is not a through hole, there is an advantage that it can be processed regardless of the thickness of the wiring board. It goes without saying that the present invention can also be applied to wiring boards that use metal materials for the core material.

[Brief explanation of drawings]

Figure wJ1 is a cross-sectional view showing the manufacturing process of a conventional wiring board.
The figure is a cross-sectional perspective view of a conventional wiring board, Figure 3 is a cross-sectional view showing the manufacturing process of a wiring board according to an embodiment of the present invention, and Figure 4 is a visit to the laser drilling device used in the manufacturing process of the present invention. figure. Codes in the diagram: 1...Insulating substrate, 2...
Copper foil layer, 3...Adhesive layer, 4...Insulated horizontal wire, 5...Insulating layer, 6...Mask layer, 7... ... Through hole, 8 ... Metal conductor layer, 9 ... Hole portion, 10 ... Plating film, 21 ... Rator cursed part, 22・・・・・・
Laser introduction path, 23... Lens, 24...
...Workpiece. 5 Figure 1 Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) In a wiring board formed by wiring a desired circuit pattern of insulated wire on an insulated substrate, a hole that reaches at least the surface of the core conductor of the insulated wire; A wiring board characterized in that a conductor layer is provided on the surface of the core edge conductor. (2) a step of depositing an insulating adhesive layer on an insulating substrate; a step of wiring an insulated bonded wire on the insulating adhesive layer;
a step of providing an insulating resin layer to cover the exposed surface of the insulating coated wire; a step of forming a non-conforming mask layer having no catalytic properties for electroless plating on the surface of the insulating resin layer; and a step of applying a laser beam. a step of providing a hole to partially expose the conductor surface of the insulated wire by irradiation; a step of forming a conductor layer on the inner wall surface of the hole and a surface of the conductor; A method for manufacturing a wiring board, comprising a step of removing the wiring board. (3) The method for manufacturing a wiring board according to claim 2, characterized in that a YAG laser is used for the laser light source. (4) The method for manufacturing a wiring board according to claim 2, wherein a carbon dioxide laser is used as the laser beam.