JPS62230093A - Double-sided wiring board and manufacture of the 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 Field of Industrial Application The present invention relates to a double-sided wiring board used in a wide variety of electronic devices and a method for manufacturing the same.

2. Description of the Related Art In recent years, as the demand for lighter, thinner, and shorter electronic devices has increased, increasing the density of these electronic circuits has become an essential requirement.

Under these circumstances, the demand for high-density printed wiring boards, especially double-sided wiring boards, is rapidly increasing in many fields of electronic equipment.

A conventional double-sided wiring board has a structure as shown in FIG. 6.

In FIG. 6, 1 is an insulating substrate, 2&, 21) is a circuit conductor layer, 3 is a through hole, and 4 is a through hole conductor layer. This double-sided wiring board is usually a through-hole type,
The circuit conductor layers 2a and 2b provided on both the front and back surfaces of the insulating substrate 1 are electrically connected by making the through holes 3 conductive.

A method for manufacturing such a through-hole connection type double-sided wiring board uses a so-called copper-clad laminate in which electrolytic copper foil is adhered to both the front and back surfaces of an insulating substrate 1 made of a synthetic resin substrate such as paper phenol or glass epoxy. After making the inner wall surface of the through hole 3 electrically conductive by successively performing steps such as hole processing, activation treatment, electroless copper plating treatment, and electrolytic copper plating treatment, the desired circuit is formed by photoetching or the like. It is made by the method of forming the conductor layers 21L and 2b.

Problems to be Solved by the Invention However, in such a through-hole connection type double-sided wiring board, the through-hole plating process is extremely complicated, which not only makes it uneconomical, but also lacks the reliability of the through-hole connection. Also, since the through-hole requires a large space, it is difficult to increase the density of the circuit.

Means for Solving the Problems In order to solve the above-mentioned problems, the double-sided wiring board according to the present invention is provided with circuit conductor layers on both the front and back layers of a plate-shaped resin molded body with metal wires embedded in predetermined positions. Wires electrically connect circuit conductor layers.

Function: With this configuration, a double-sided wiring board is obtained in which the circuit conductor layers on both sides are electrically connected using metal wires embedded in synthetic resin, and the reliability of the connection is improved compared to through-hole connection types. This makes it possible to easily increase the density of wiring circuits and to realize an economical double-sided wiring board.

EXAMPLES Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a sectional view of essential parts of a double-sided wiring board according to an embodiment of the present invention. In FIG. 1, 6 is a metal wire;
is a synthetic resin layer, and 72L and 7b are circuit conductor layers (conductive metal layers).

The manufacturing method of the double-sided wiring board having the above structure will be explained in detail below.

The double-sided wiring board according to the present invention is manufactured by first embedding a plurality of metal wires 5 having arbitrary wire diameters in a synthetic resin 6 at predetermined intervals as shown in FIG. 2, and then hardening the synthetic resin 6. Make a columnar resin molded body.

In this case, it is desirable that the metal wire 6 has a small electrical resistance, but in this embodiment, the diameter is 0.1 to 1.010.
A copper wire coated with an insulation coating having an Iφ range was used. As a method of arranging the copper wires at predetermined intervals, a guide plate with through holes having approximately the same dimensions as the metal wires 6 is used in advance at predetermined positions, and a mold having an arbitrary volume is filled with the synthetic resin 6. After the metal wire 6 was inserted into the mold and the synthetic resin 6 was cured, the mold was removed to produce a columnar resin molded body.

On the other hand, the synthetic resin 6 for casting into which the metal wire 5 is embedded has not only excellent electrical insulation properties but also heat resistance, moisture resistance, and chemical resistance.

Solvent Resistance 9 It is necessary to have excellent properties such as mechanical strength and processability, and epoxy resin is a synthetic resin material that satisfies these properties.

Phenolic resin, melamine resin, unsaturated polyester resin, polybutadiene resin, xylene resin.

In addition to thermosetting resins such as silicone resin, polyimide resin, polyurethane resin, and sialphthalate resin, there are thermoplastic resins such as polysulfone, and in this example, epoxy resin is used, and silica, alumina, etc. The metal wire 5 was embedded using an acid anhydride-based or amine-based curing agent.

Next, as shown in FIG. 3, the columnar resin molded body with the metal wire 6 buried in a predetermined position is cut in the thickness direction to a desired thickness, and the fractured surface of the metal wire 6 is cut into a desired thickness. A plate-shaped resin molded body was made with a structure in which the resin was exposed on both the front and back sides.

As cutting methods in this process, we tried using a metal cutter rotated at high speed, a diamond force cutter, and a laser processing method.

The plate-shaped resin moldings obtained by cutting using these methods were polished on both the front and back surfaces using sandpaper, if necessary, to give the surfaces smoothness.

Then, as shown in FIG. 4, the metal wire 5 is buried in a predetermined position, and the entire main surface of the plate-shaped resin molded body with its both ends exposed is coated by electroless plating, vacuum evaporation, sputtering, etc. Conductive metal layer 71L such as copper or nickel
, 7b is deposited, and then, as shown in FIG. 6, unnecessary portions of the conductive metal layer 7& are formed by a method such as a photoetching method.

7b was removed to form desired circuit conductor layers 7a and 7b.

In forming the circuit conductor layers a and 7b, as described above, the conductive metal layer 7 is formed on the entire main surface of the plate-shaped resin molded body.
? In addition to the method of removing unnecessary parts of the conductive metal layer after depositing L and 7b, it is also possible to directly deposit the conductive metal layer in the required circuit diagram shape by electroless plating on both the front and back layers of the plate-shaped resin molded body. It may also be carried out by a so-called additive method.

Furthermore, as a simpler circuit forming method, there is a method in which a conductive resin is directly applied to the required circuit diagram shape by screen printing and then baked, but in the present invention, any of the above-mentioned methods may be used.

Effects of the Invention As is clear from the above explanation, the double-sided wiring board according to the present invention has a desired circuit conductor layer formed on both the front and back layers of a plate-shaped resin molded body in which metal wires are embedded in predetermined positions. It has a structure in which circuit conductor layers are connected on both sides via metal wires.

Therefore, the double-sided wiring board according to the present invention can reduce the connection resistance of the front and back circuits, and also improve the reliability of the connection, compared to the so-called through-hole connection type, which connects both sides by making the through holes conductive. In addition to this, since there are no through holes, the degree of freedom in circuit design increases and high-density circuits can be formed.

On the other hand, the double-sided wiring board according to the present invention does not require complicated processes such as through-hole plating, and can achieve double-sided connection in an extremely simple process, making it possible to realize a low-cost double-sided wiring board and making surface connection without lead wires possible. The double-sided wiring board is suitable for mounting molded chip components to create high-density electronic circuits.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of a double-sided wiring board according to the present invention, FIG. 2 is a perspective view of a columnar resin molded body for explaining a method of manufacturing a double-sided wiring board according to an embodiment of the present invention, and FIG. Similarly, FIGS. 4 and 5 are perspective views of the plate-shaped resin molded body, sectional views for explaining the process of forming circuit conductor layers on both the front and back surfaces of the plate-shaped resin molded body, and FIG. 6 is a conventional example. FIG. 2 is a sectional view of essential parts of a double-sided wiring board. 5...Metal wire, 6...Synthetic resin layer, 7
1,7b... Conductive metal layer. Name of agent: Patent attorney Toshio Nakao and 1 other person5-
Gold A-Roku Figure 2

Claims (2)

[Claims] (1) A double-sided wiring board having a structure in which circuit conductor layers are provided on both the front and back layers of a plate-shaped resin molded body in which metal wires are embedded in predetermined positions, and the circuit conductor layers are electrically connected by the metal wires. (2) A columnar resin molded body with multiple metal wires embedded in predetermined positions is made, and the resin molded body is cut in the thickness direction to form a plate-shaped resin molded body with the broken surfaces of the metal wires exposed on both the front and back layers. 1. A method for manufacturing a double-sided wiring board, comprising: forming a desired circuit conductor layer on both the front and back surfaces of the plate-shaped resin molded body.