JPS63137498A - Manufacture of through-hole printed 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] [Technical Field] The present invention relates to a printed wiring circuit board on which electronic components such as semiconductor elements, resistors, and capacitors are mounted and used to configure various electronic and electrical devices. In particular, the present invention relates to printed wiring boards in which circuits are configured in multiple layers and require through-hole connections for electrical connections between layers.

[Background technology]

In recent years, electronic devices have become smaller and more sophisticated, and lower costs are being pursued. Along with this, printed wiring has been strongly required to have higher density, higher reliability, lower cost, and the like.

The density of printed wiring boards can be increased by making the wiring finer and multilayering the wiring, but in reality, the through-hole connection method between multilayer circuits has the following drawbacks.

(1) In order to plate through-hole portions, electroless plating and electrolytic plating must be used in combination, which requires a large number of steps and is complicated.

Furthermore, since the surface circuit is formed after through-hole plating, the thickness of the copper layer to be etched (copper foil thickness (ten plating thickness)) is thick, making it impossible to form fine circuits.

(2) On the other hand, a method called the full additive method requires fewer steps because it is possible to form through-hole areas and surface circuits at the same time by electroless plating. The physical properties of plated copper are unstable, and the reliability of through-hole connections is low.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a method of manufacturing a printed wiring board with high reliability of through-hole connections and a simple process at a low cost.

[Disclosure of the invention]

In the present invention, a metal electrode plate whose other side is sealed with an insulator is closely attached to one side of a circuit board in which through-hole holes are formed so that at least the through-hole holes are covered with the metal electrode plate, and then the metal electrode plate is The present invention provides a method for manufacturing a through-hole printed board, characterized in that electrolytic plating is performed using the board as a negative electrode, and plating metal is deposited in the through-holes.

Hereinafter, the present invention will be explained based on the drawings. FIG. 1 is a schematic diagram for explaining the present invention in detail. FIG. 1(a) shows the state before electrolytic plating, and FIG. 1(b) shows the state after electrolytic plating. In this figure, 1 is a circuit board, 2 is a conductor circuit, 3 is an electrode substrate, 4 is an insulating seal attached to the electrode substrate, 5 is a through hole, and 6 is a metal pillar. As shown in these figures, the gist of the present invention is to perform electrolytic plating to form metal pillars 6 as conductors within the through holes 5, and for this purpose, the metal pillars 6 formed around the through holes 5 are The electrode substrate 3 is brought into close contact with the W-body circuit 2, and plating is performed to deposit a metal column within the through hole 5. The electrode substrate 3 used in this case is provided with an insulating seal 4 on the surface opposite to the through-hole 5 side to prevent metal deposition on that surface.

By doing the above, both sides of the circuit board can be connected with the conductor.

Note that the present invention includes the following embodiments.

In other words, a circuit board with through-holes is
A metal layer necessary for forming a circuit or a circuit has already been formed on at least one side of the substrate.

The metal electrode plate may be formed in a single layer or in multiple layers, or may be formed so that its surface is partially conductive. Further, the metal electrode plate may be surface-treated to improve releasability from the plating layer.

Furthermore, the metal electrode plate may include a case in which a part of the metal electrode plate is intended to ultimately constitute a part of a printed wiring board.

The through-holes and the metal electrode plate may be brought into close contact with each other mechanically or temporarily or semi-permanently by using an adhesive, an adhesive, or the like.

Hereinafter, a detailed explanation will be given based on examples.

(Example 1) FIG. 2 shows a process diagram of this example. The explanation will be given below according to this figure.

Adhesive sheet 1 is placed on both sides of a double-sided copper clad plate 7 with a thickness of 0.4 m.
After attaching the glass base material and the epoxy resin laminate (not shown), a through hole 9 of 0.5 wΦ is formed by drilling, and then one side is insulated and sealed 14, and the other side is sealed. A stainless steel plate 13 plated with 2 to 3 μm of copper plating 12 was bonded to one side. FIG. 2(a) shows this state. Note that here, 8 indicates a copper foil, and 11 indicates an electrode plate.

This laminate was then heated in a copper pyrophosphate plating bath for 2 to 5 minutes.
Electrolytic plating was performed using the electrode plate 11 under the condition of "A/100 cm" until the plated copper pillar 15 reached the opening surface of the through hole 9. FIG. 2(b) shows this state.

After washing with water, the electrode plate 11 was peeled off at the interface with the copper plating layer 12, and then soft etching and peeling of the adhesive sheet IO were performed to obtain a double-sided copper-clad plate 16 with completed through-hole connections. FIG. 2(C) shows this state.

Next, both sides were etched using a conventional method to form a circuit 18. FIG. 2(f) shows this state. - The through-hole reliability of the obtained printed board was good. The copper thickness to be machined and notched was sufficient to be 18μ, making it possible to form a circuit with a width of 50μ.

(Example 2) FIG. 3 explains the process of this example. here 19
20 is paper base-phenolic resin single-sided copper clad plate, 20 is copper foil,
21 is an adhesive sheet, 22 is an epoxy resin adhesive, 23 is a copper foil treated to strengthen adhesion, and 24 is a plated copper pillar. This will be explained below.

Paper base material with a thickness of 0.8 mm - phenolic resin single-sided copper clad board (
After roughening the resin substrate surface of the copper foil (18μ), an epoxy resin adhesive was coated on the surface and cured to B stage. Next, after laminating a plating-resistant adhesive sheet on the copper foil, a 0.8nΦ through hole was formed by drilling, and then a 35μ copper foil with one side treated to strengthen adhesion was placed so that the treated side overlapped the adhesive side. The copper foil was bonded to a single-sided copper foil plate that had been laminated with through-holes using a low-pressure hot press. Next, the adhesive sheet was laminated onto the surface of the bonded 35 μm copper foil, and then the copper foil was used as an electrode, and electrolytic plating was performed in the same manner as in Example 1 until the plated copper reached the opening surface of the through hole.

After washing with water, the adhesive sheets on the surfaces of both copper foils were peeled off to obtain a double-sided copper-clad plate with completed through-hole connections. Next, the copper foils on both sides were etched using a conventional method to obtain a printed wiring board.

(Example 3) FIG. 4 outlines this example. here 25
26 is a copper foil, 27 is an adhesive sheet, 28 is an adhesive sheet, 29 is a stainless steel plate, 3o is a copper plating layer, and 31 is a plated copper pillar.

This will be explained below.

A glass base material with a thickness of 0.411 mm - an epoxy resin single-sided copper-clad board (copper foil 18 μm), a plating-resistant adhesive sheet was pasted on the copper foil surface, and an epoxy adhesive sheet was pasted on the substrate surface. After that, a through hole with a diameter of 0.8 mm was processed using a drill.

One side is insulated and sealed with an adhesive sheet, and the other side is approximately 10μ
The copper-plated plate was laminated on the copper-plated surface of a stainless steel plate whose surface had been blackened so that the adhesive sheet surfaces faced each other, and the two were bonded together by low-pressure hot pressing. Next, the laminate was electrolytically plated in a plating solution in the same manner as in Example 1, and then the stainless steel plate was coated with a copper plating layer (10μ).
A double-sided copper-clad board with completed through-hole connections was obtained. Etch the copper foil on both sides using a conventional method,
A printed wiring board was obtained.

(Example 4) FIGS. 5(a), (b), (C), and (d) are diagrams explaining the steps of this example. Here, 32 is the glass base material -
Epoxy resin single-sided copper clad plate, 33 conductor circuit, 34 adhesive sheet, 35 through hole, 36 stainless steel plate, 37 copper plating layer, 38 plating-resistant adhesive sheet, 3
9 is a photosensitive resist image, 40 is a plating circuit, 41 is a solder resist, and 42 is a plated copper pillar. This will be explained below.

After etching a 0.4 mm thick glass substrate-epoxy resin single-sided copper-clad board (copper foil 18μ) to form a conductor circuit, an epoxy resin adhesive sheet was pasted on the board surface. , drill through-hole hole (0
, 5 cranes Φ) were formed (Figure a).

On the other hand, a stainless steel plate (1
A photosensitive resist image having a pattern opposite to the desired circuit pattern was formed by a conventional method on a copper plating layer having a thickness of 0.7 m. Next, the stainless steel plate was subjected to electrolytic plating in a plating bath to form a plating circuit having approximately the same thickness as the resist image thickness (Figure b).

After blackening the surface of the plated circuit on the stainless steel plate, the circuit board is laminated and aligned so that the through-hole part of the adhesive sheet surface faces the plated circuit,
Both were bonded together by low pressure heating. Next, a solder resist is applied onto the etched circuit on the surface except for at least the through-hole areas, and after hardening, the laminate is electrolytically plated again in a plating bath under the same conditions using the stainless steel substrate as an electrode. Then, a plated column was formed inside the through hole until it was integrated with the etched circuit on the surface (Figure C).
.

After washing with water, the stainless steel plate was peeled off at the interface with the copper plating layer, and then soft etched to obtain a through-hole printed wiring board with circuits formed on both sides (Figure d).

(Example 5) Through-hole printing was performed in the same process as in Example 4, except that laser plating was performed as a condition for electrolytic plating inside the through-holes! I got avi.

All of the printed wiring boards obtained in Examples 1 to 5 had good through-hole connection reliability in the thermal shock test.

Further, as for circuit formation on the surface, an etching circuit with a width of 50 μm was formed in Examples 1 to 3, and a fine plating circuit with a width of 30 μm was formed in Examples 4 to 5.

[Effects of the Invention] The present invention is characterized in that a metal electrode plate, the other side of which is sealed with an insulator, is tightly attached to one side of a circuit board in which through-hole holes are formed so that at least the through-hole holes are covered with the metal electrode plate. Then, electrolytic plating is performed using the metal electrode plate as a negative electrode, and the plated metal is deposited in the through holes. Therefore, the reliability of the through hole connections can be increased, and the printed wiring board can be manufactured using a simple process. It has the effect of being able to be manufactured at low cost.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the outline of the process of this invention, Figure 2,
FIG. 3, FIG. 4, and FIG. 5 are diagrams for explaining the present invention in detail. 1...Circuit board 2...Conductor circuit 3...Electrode substrate 4...Insulating seal 5...Through hole 6...Plated metal column

Claims (1)

[Claims] (1) In the method of manufacturing a through-hole printed board, a metal electrode plate whose other side is sealed with an insulator is placed on one side of a circuit board with through-hole holes formed so that at least the through-hole holes are covered with the metal electrode plate. 1. A method for manufacturing a through-hole printed board, comprising the steps of bringing the metal electrode plate into close contact with each other, and then performing electrolytic plating using the metal electrode plate as a negative electrode to deposit plating metal within the through-hole.