JPH06188560A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To easily obtain a double-sided printed wiring board with highly reliable through hole jumper part by a simple process using thermoplastic resin as an insulating base sheet. CONSTITUTION:This manufacturing method is composed of a process in which circuit patterns 2a' and 2b', consisting of the required conductive metal layers 2a and 2b, are formed on both main surfaces of a thermoplastic resin sheet 1, and a process in which the thermoplastic resin sheet 1, on which circuit patterns 2a' and 2b' are formed, is heated up, the corresponding part of the circuit patterns is selectively press-inserted and deformed into the thermoplastic resin sheet 1 by press-bonding the prescribed region of the circuit patterns 2a' and 2b' from one main surface side, and the circuit patterns 2a' and 2b' on both main surfaces are connected (5).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a double-sided printed wiring board using a thermoplastic resin as an insulating base material.

[0002]

2. Description of the Related Art As is well known, double-sided printed wiring boards have been widely put to practical use in various electronic devices and electric devices. A double-sided printed wiring board of this type is generally manufactured as follows. That is, on both sides of the insulating substrate such as glass / epoxy resin,
For example, a base plate to which a conductive metal foil such as a Cu foil is attached is first prepared, and a through hole is formed at a place where conduction is made between both surfaces by drilling, for example. Next, a chemical plating process and an electroplating process are sequentially performed to deposit and form a conductive metal layer on the inner wall surface of the formed through hole, and electrical conduction is established between both surfaces. After that, the Cu foil stuck on both sides is subjected to so-called photo-etching treatment,
A double-sided printed wiring board is obtained by forming a required circuit pattern.

[0003]

However, the following inconveniences are recognized in the above-mentioned method for manufacturing the double-sided printed wiring board. That is, in order to connect the circuit patterns on both surfaces with each other, the steps of drilling and plating are required. In addition, not only an expensive drilling device is required for drilling, but also burrs are generated on the wall surface of the drilled hole, so a good plating layer (highly reliable conductive metal layer) can be formed. There are also things that cannot be formed. On the other hand, in the plating process, there is a problem that a large amount of plating solution is used, large-scale equipment is required due to different usage of plating solution, and additional equipment is required for processing the used plating solution. .

In addition, with respect to the obtained double-sided printed wiring board, the plating layer that conducts between the circuit patterns on both sides is broken due to thermal stress due to the difference in thermal expansion coefficient from the insulating base material. However, there is a problem that the electrical connection reliability is poor.

The present invention has been made in view of the above circumstances, and facilitates a double-sided printed wiring board having a highly reliable through-hole connecting portion using a thermoplastic resin as an insulating base material in a simple process. The object of the present invention is to provide a manufacturing method that can be obtained.

[0006]

A method of manufacturing a printed wiring board according to the present invention comprises a step of forming a circuit pattern composed of a required conductive metal layer on both main surfaces of a thermoplastic resin base material, and the circuit. The thermoplastic resin base material on which the pattern is formed is heated, and a predetermined area of the circuit pattern is pressure-bonded from at least one main surface side to selectively press-fit or deform the corresponding circuit pattern on the thermoplastic resin base material. , And a step of connecting circuit patterns on both main surfaces.

[0007]

In the method of manufacturing a printed wiring board according to the present invention, the thermoplastic resin forming the main part of the insulating base material having the required circuit patterns formed on both main surfaces is heated and slightly softened. Selectively pressurize and crimp a predetermined area of the pattern. Due to this selective pressure bonding, in other words, local pressure, the corresponding portions of the conductive metal layer are selectively bent and deformed easily toward the softened thermoplastic resin-based material side to correspond to each other. The areas to be contacted are brought into contact with each other to achieve an electrical connection. In other words, the circuit patterns on both sides form a highly reliable electrical connection by partially deforming and press-fitting, and the cost and productivity are greatly improved and improved.

[0008]

Embodiments of the present invention will be described below with reference to FIGS. 1 (a) to 1 (d).

FIGS. 1 (a) to 1 (d) are sectional views schematically showing an embodiment of the present invention. First, an insulating base material mainly composed of a thermoplastic resin, for example, a thickness cut to a required size. A Cu foil sticking film (material) 3 is prepared by sticking Cu foils 2a and 2b having a thickness of 35 μm on both sides of a thermoplastic polyimide resin film 1 having a thickness of 50 μm (FIG. 1 (a)). Then, the double-sided Cu foils 2a and 2b of the Cu foil-attached film 3 are each subjected to photoetching treatment which is a conventional method,
The required circuit patterns 2a 'and 2b' are formed (FIG. 1 (b)).

In this way, the required circuit pattern 2
After forming a ′ and 2b ′, the circuit patterns 2a ′ and 2b ′ are formed.
The thermoplastic polyimide resin film 1 supporting (supporting) is heated at a temperature of about 200 ° C. to be softened, and the predetermined regions (regions to be connected to each other) of the circuit patterns 2a ′ and 2b ′ are For example, a pair of 1mm diameter punches 4a,
Selectively press from both sides with 4b, for example, with pressure of about 200 kg / cm ² (Fig. 1 (c)). The circuit pattern 2a 'supported (carried) on the thermoplastic polyimide resin film 1 in the softened state by this selective pressurization and pressure bonding,
The Cu foil in the pressing / pressing area of 2b ′ is easily bent and deformed inside the thermoplastic polyimide resin film 1 and the areas corresponding to each other are in contact with each other and electrically connected (through hole connection).
To form. Then, selective pressurization and pressure bonding by the punches 4a and 4b are sequentially performed on the connection planned regions of the circuit patterns 2a 'and 2b', whereby a double-sided printed wiring board having a required through-hole connection 5 is obtained. (Fig. 1 (d)).

In the above embodiment, the insulating base material has a thickness of 50 μm.
Although a thermoplastic polyimide resin film of m was used, this thickness is not limited to 50 μm and is generally several μm.
It can be selected in the range of about m to several 100 μm, and further, for example, polyphenylene sulfide resin film, polysulfone resin, polycarbonate resin, polystyrene resin, polyether sulfone resin, polyacetal resin, polyether ketone resin, polyether imide resin, Thermoplastic resin film (thin plate) such as polyphenylene oxide resin, acrylic resin, polyethylene resin, ABS resin, polyamide resin, polyvinyl chloride resin, fluororesin, polyetheretherketone resin, or these thermoplastic resins and glass cloth or glass fiber It may be in the form of a thin plate obtained by combining and. Also, the circuit pattern is not limited to the Cu foil type, for example,
Other conductive metal such as AL foil type may be used, and the formation / form thereof may be a vapor-deposited metal layer or a screen-printed metal layer. Furthermore, the formation of through-hole connection may be performed simultaneously instead of individually. For example, a means for placing on a flat surface and heating / pressurizing / compressing from one main surface (one surface) side with a punch is adopted. Good. The formation of the through-hole connection is not limited to selective heating, pressurization, and pressure bonding, and may be performed while softening the insulating base material by, for example, ultrasonic welding or electric welding.

[0012]

As described above, according to the present invention, the work of making a hole in the insulating base material for wiring, and the work of forming the conductive layer by plating on the inner wall surface of the hole after making the hole are complicated. It is possible to easily obtain a double-sided printed wiring board in which circuit patterns on both surfaces are through-hole connected without requiring any steps. Since the through-hole connection is formed by the partial press-fitting / deformation of the circuit pattern, damage (breakage) due to the effect of thermal expansion of the insulating base material for wiring can be avoided, and highly reliable electrical connection can be achieved. Hold and exert. That is, there is a great advantage that a highly reliable double-sided printed wiring board can be mass-produced with high yield while simplifying the manufacturing process.

[Brief description of drawings]

FIG. 1 schematically shows an embodiment example of a method for manufacturing a printed wiring board according to the present invention, in which (a) is a cross-sectional view showing the structure of a Cu foil-bonded thermoplastic resin film as a material, (b) Is a cross-sectional view showing a state where the Cu foil on both sides is patterned into a circuit,
(c) is a cross-sectional view showing a state in which a required area of a double-sided circuit pattern is selectively heated, pressed, and pressure-bonded to form a through-hole connection,
(d) is a cross-sectional view of the manufactured double-sided printed wiring board.

[Explanation of symbols]

1 ... Thermoplastic resin-based insulating base material (film) 2a, 2b ...
Cu foil 2a ', 2b' ... Circuit pattern 3 ... Cu foil pasting film 4a, 4b ... Punch 5 ... Through hole connection

Claims (1)

[Claims] 1. A step of forming a circuit pattern composed of a required conductive metal layer on both main surfaces of a thermoplastic resin base material, and heating the thermoplastic resin base material on which the circuit pattern is formed to form a circuit. A predetermined area of the pattern is pressure-bonded from at least one main surface side to selectively press-fit and deform the corresponding circuit pattern of the thermoplastic resin base material to connect the circuit patterns on both main surfaces. A method of manufacturing a printed wiring board, comprising: