JPH02275695A - Multilayer printed circuit board - Google Patents

Abstract

PURPOSE:To prevent burr from generating and to improve reliability of electric connection by forming front and rear pads having inner layer through holes or front and rear wirings at the hole as a starting point. CONSTITUTION:Circular front surface pad 1 and rear surface pad 2 are formed at points A, B as centers on forming part of a through hole 7 on the main surface of both-side printed circuit board 10. Inner layer through holes 3 electrically connected to the pads 1, 2 are formed at points A', B' near the pads 1, 2. In this case, the position of the hole 3 is deviated from the position of the through hole, and the pads 1, 2 and the hole 3 are formed in a 8 shape. Thus, the pad 1 is electrically connected to the pad 2 via the hole 3. Thus, it can prevent burr to improve an electric connection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multilayer printed wiring board, and more particularly to patterns and through-holes of an inner layer double-sided printed wiring board for signals in a multilayer printed wiring board in which a plurality of double-sided printed wiring boards are laminated.

[Conventional technology]

Conventionally, when manufacturing a multilayer printed wiring board by laminating a plurality of double-sided printed wiring boards, the inner layer double-sided printed wiring board for signals has a land and an inner layer for electrical inspection of the trailing portion of the outer layer through-hole of the double-sided printed wiring board for signals. It was necessary to provide a through hole.

[Problem to be solved by the invention]

However, in the case of a multilayer printed wiring board using such a double-sided printed wiring board for signals, there are the following drawbacks.

(1) Since the through holes in the outer layer overlap the through holes in the inner layer double-sided printed wiring board, [burrs] are likely to occur when forming the through holes in the outer layer. This Paris may cause short-circuit accidents, etc.

In order to solve the above-mentioned problems, a structure has been developed in which only pads are provided in the trailing portion of the outer layer through-holes of double-sided signal printed wiring boards without providing inner layer through-holes, but this case has the following problems.

(1) When electrically inspecting an inner layer double-sided printed wiring board, there is a fee for applying a probe from both sides, but since there are no inner layer through holes, it is extremely difficult to create a jig for electrical inspection.

Furthermore, as a common drawback of the above two conventional structures, (r1+
) Since the electrical connection between the double-sided printed wiring board for No. FG and the outer layer through-hole is carried out only at the intersection of 1/- of the land or pad of the signal double-sided printed wiring board of the circumference of the outer layer through-hole, the electrical This may result in insufficient follow-up.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and provide a multilayer printed wiring board that does not generate flash and has good electrical continuity.

[Means for solving problems]

The structure of the multilayer printed wiring board of the present invention includes a double-sided wiring board having a plurality of first through holes as an inner layer, a plurality of second through holes penetrating both the front and back main surfaces, and the second through holes penetrating the double-sided wiring board. A pad is provided on each of both main surfaces of the front double-sided wiring board, and a first pad electrically connected to the pad is provided in the vicinity of the pad so that the opening portion does not become heavy.
It is characterized by having a through hole.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1(a) is a plan view seen through the surface showing the relationship between the signal double-sided printed wiring board and the through-holes of a multilayer printed wiring board according to an embodiment of the present invention. -m
1(C) is a sectional view taken along line -m', and shows a situation in which the double-sided printed wiring board for signals shown in FIG.

In FIGS. 1(a), (b), and (c), in this embodiment, the wiring between the through-hole 7 at point A and the through-hole 7 at point B of the multi-node printed wiring board 20 is first wired for signal. A case is shown in which the wiring board 10 with markings on both sides is used.

In a portion of the double-sided printed wiring board 10 where the through-hole 7 is to be formed, a circular front pad 1 and a back pad 2 having a diameter larger than that of the through-hole 7 are formed centered on points A and B. Further, in the vicinity of the surface pad 1 and the surface pad 2, an inner layer through hole 3 electrically connected to the pads 1.2 is formed at points A'+B'. On this occasion,
The hole position of the inner layer through hole 3 is shifted from the hole position of the through hole so that the hole inner wall part (cylindrical shape) of the through hole 7 does not become N to the hole inner wall of the inner layer through hole 3. For this reason,
Surface pad 1. Back pad 2. and inner layer through hole 3
The shape was a gourd shape as shown in Figure 1(a).

As a result, the surface pads 1 and 2fK surface pads 2 are electrically connected to each other through the inner layer through-holes 3. This is done by the front circuit 4 and the front circuit 5 through the peer hole 6, but the front circuit 4 and the back circuit 5
This may be followed by the front pad 1 or the back pad I at point A, or by the inner layer through hole 3.

In the case of this embodiment, the electrical continuity between the through-hole 7 and the same soil is as follows: through-hole 7 (point A) → front pad 1 and back pad 2 (point A) → inner layer through-hole 3 (point A') → surface circuit 4 → Pier hole (0 points) → Back circuit 5 → Pier hole 6 (Point D) → Clothes circuit 4 → Inner layer through hole 3 (Point B')
→ The front pad 1 and the back pad 2 (point B) → the through hole 7 (point B).

Next, FIGS. 2(a) to 2(0) show a method of manufacturing the multilayer printed wiring board of the above embodiment.

In FIG. 2(a), an insulating plate 12 having a copper foil 11 on its main surface is prepared, and a through hole 13 is formed by drilling. Next, the entire surface of the insulating plate 12, including the inner wall of the through hole 13, is subjected to ordinary catalyst treatment, electroless copper plating, and electric steel plating to form a copper plating 14 (see FIG. 2(b)).
). Next, the copper foil 11 and the copper plating 14 are etched on the insulating plate 12 by the usual printing-etching method ζ, and the front surface pad, the back pad 2, the inner layer through hole 3, the front surface circuit 4, and the back surface circuit 5 are simultaneously formed. A double-sided printed wiring board IO for signals was prepared (FIG. 2(C)). Next, from the main surface of this double-sided printed wiring board 10, 'electrical inspection probe 1
5 and conduct an electrical inspection (Fig. 2(d)).

Next, between the insulating plates 170 having the copper foil 16 on one side, the above-mentioned double-sided printed wiring board 10 for signals, two double-sided printed wiring boards 19 for power/ground with conductor patterns formed on both sides in advance, and the prepreg 18 are placed. A laminate 21 was obtained by arranging them one on top of the other and heat-pressing them (FIG. 2(e)). Next, through-holes are provided in the through-hole portions of the laminate 210, and the entire surface is formed as shown in FIG. 2(b).

After copper plating was performed in the same manner as in (c), the surface was printed and etched to form through-holes and the outermost layer circuit 8, thereby obtaining a multilayer printed wiring board 20.

The multilayer printed wiring board 20 obtained in this way has a gap between the double-sided printed wiring board for signals 10 and the through-hole 7, which is generated when the through-hole 3 of the double-sided printed wiring board for signals is destroyed by a drill. Good through hole 7
and the pads 1.2 on the front and back sides of the double-sided signal board were obtained.

By the way, as another embodiment, the structure of the multilayer printed wiring board is the same as that of the above embodiment except that the front pad 1 and the back pad 2 of FIG. 1 (ω) are not circular but polygonal. A multilayer printed wiring board was obtained using the same manufacturing method.

In this example, as in the previous example, there was no occurrence of cracks in the through-hole, and a good shape and subsequent condition of the through-hole were obtained.

〔Effect of the invention〕

As explained above, the present invention provides, when wiring between through-holes of a multilayer printed wiring board is carried out using a double-sided printed wiring board in an inner layer, pads on the front and back sides having inner-layer through-holes are provided in the trailing portions of the through-holes, By performing wiring on the front and back using these front and back pads or inner layer through-holes as starting points, it is possible to prevent the occurrence of flashing caused by the through-holes of the inner layer double-sided printed wiring board being destroyed by drilling the through-holes, and also to Electrical inspection can be easily performed by simply applying the probe from the front or back side, and furthermore, since the through-hole is followed by both the front and back pads, subsequent reliability can be greatly improved. effective.

[Brief explanation of drawings]

FIG. 1 (ω is a plan view seen through the main parts of a multilayer printed wiring board according to an embodiment of the present invention, FIG. Figure 1 (d)
Figure 1 (cross-sectional view of the product manufactured with the inner layer of the double-sided board), Figure 2
Figures (a) to 2(f) are cross-sectional views sequentially showing a method of manufacturing a multilayer printed wiring board according to an embodiment of the present invention. 1...Front surface pad, 2...Back surface pad, 3...Inner layer through hole, 4...Surface circuit, 5...Back side Circuit, 6...Pier hole, 7...Through hole, 8...
・Outermost layer circuit, 10...Double-sided printed wiring board for signals, 11.16...Steel foil, 12.17...
...Insulating plate, 13...Through hole, 14...
・Pure plating, 15...Gloves for electrical inspection, 1
8...Prepreg, 19...Double-sided printed wiring board for electromagnetic and grounding, 20...Multilayer printed wiring board, 21...Laminated body. Agent Patent Attorney Susumu Uchihara He He He Bee ′＊ Groan

Claims (1)

[Claims] A multilayer printed wiring board comprising a double-sided wiring board having a plurality of first through-holes as an inner layer and a plurality of second through-holes penetrating both the front and back principal surfaces, wherein the double-sided wiring board is penetrated by the second through-holes. A multilayer, characterized in that a pad is provided on each of both main surface portions, and a first through hole is provided in the vicinity of the pad and electrically subsequent to the pad so that the opening portion does not become heavy. Printed wiring board.