JP2629917B2 - Multilayer printed wiring board and method of manufacturing the same - Google Patents

Description

The present invention relates to a multilayer printed wiring board and a method for manufacturing the same, and more particularly, to a multilayer printed wiring board in which a plurality of double-sided printed wiring boards are stacked and a method for manufacturing the same.

[Conventional technology]

Conventionally, when a multilayer printed wiring board is manufactured by laminating a plurality of double-sided printed wiring boards, as a signal inner layer double-sided printed wiring board, lands and It was necessary to provide an inner layer through hole.

[Problems to be solved by the invention]

However, a multilayer printed wiring board using such a double-sided printed wiring board for a signal has the following disadvantages.

(A) Since the through-hole of the outer layer overlaps the through-hole of the inner-layer double-sided printed wiring board, burrs are easily generated when forming the through-hole of the outer layer.

In order to solve the above problem, a method of providing only a pad without providing an inner layer through hole at a through hole connecting portion of a signal double-sided printed wiring board has been performed. However, in this case, the following problem occurs.

(B) It is extremely difficult to prepare a jig for electrical inspection because it is necessary to apply probes from both sides when performing electrical inspection on the inner layer double-sided printed wiring board.

Further, common drawbacks of the above two conventional methods are as follows: (c) The electrical connection between the signal double-sided printed wiring board and the through-hole is one of the lands or pads of the signal double-sided printed wiring board around the through-hole. There is a problem in the reliability of the connection because the connection is performed only at the intersection of the layers.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer printed wiring board having a highly reliable connection and an electrical inspection of an inner layer double-sided printed wiring board, and a method of manufacturing the same.

[Means for solving the problem]

The multilayer printed wiring board of the present invention has a pad on both the front and back surfaces of the electrical connection portion with the through-hole of the inner layer double-sided printed wiring board,
In the vicinity of the pad, there is a connection inner layer through hole electrically connected to the pad on both the front and back surfaces of the inner layer double-sided printed wiring board, and further, the space between the pad and the front and back connection inner layer through hole is It is wired on both sides of the inner layer double-sided printed wiring board.

The method for manufacturing a multilayer printed wiring board according to the present invention includes the following steps.

(A) a step of providing a through hole in an insulating plate having copper foil on both surfaces and then plating the entire surface to form a conductive layer; (b) printing and etching the conductive layer on the surface of the insulating plate;
A step of forming an inner layer through-hole and a conductive circuit on both front and back sides to form a double-sided printed wiring board for signals; (c) in the step of forming the double-sided printed wiring board for signals,
A step of arranging pads on both front and back surfaces of a portion to be electrically connected to the through through hole, arranging the inner layer through hole near the pad, and arranging wiring on both front and back surfaces between the pad and the inner layer through hole (D) a step of electrically inspecting the conductive circuit of the double-sided printed wiring board for signals (e) printing-etching of a copper foil of an insulating plate having copper foils on both front and back surfaces to form a double-sided printed wiring board for power grounding; Step (f) A copper foil or an insulating plate having a copper foil formed on one side is disposed on an outer layer with the copper foil on the outside, and the double-sided printed wiring board for signal and the double-sided printed wiring board for power ground are connected via a pre-breg. Step of forming a laminated body by thermocompression bonding (g) After providing a through hole in the laminated body, performing copper plating on the entire surface, forming a surface conductor layer, and then printing the surface conductor layer.
Step of forming a through-hole and the outermost layer circuit on the surface by etching to obtain a multilayer printed wiring board [Example] Next, an example of the present invention will be described with reference to the drawings.

FIGS. 1 (a) to 1 (c) are a plan view and a sectional view of a double-sided printed wiring board for signal according to a first embodiment of the first invention, and the double-sided printed wiring board for signal is incorporated in a multilayer printed wiring board. It is sectional drawing of the multilayer printed wiring board explaining a situation.

FIGS. 1 (a) to 1 (c) show a first embodiment of the first invention.
First, a case is described in which the wiring between the through-hole 9 at point A1 and the through-hole 9 at point B1 of the multilayer printed wiring board 30 is performed via the double-sided printed wiring board 20 for signals, as shown in FIG.

A circular surface pad 1 and a back surface pad 2 having a diameter larger than the diameter of the through-hole 9 are formed at portions where the through-hole 9 is to be formed at the points A1 and B1 of the double-sided printed wiring board 20. A1
Inner layer through-holes 3 are formed at points A2 and B2 near points B1 and B1. Surface pad 1 and inner layer through hole 3
Is wired by the front surface drawing circuit 4, and between the back surface pad 2 and the inner layer through hole 3 is the back surface drawing circuit 5.
Is wired. The two inner layer through holes 3 are wired by the front surface conductive circuit 6 and the rear surface conductive circuit 7 via the via hole 8 formed at the point C. As a result, the wiring of the signal line between the through-holes 9 is separated from the inner wall of the through-hole 9 by the surface pads 1 and the back pads 2, the surface drawing circuit 4 and the surface drawing circuit 5, the inner layer through hole 3, the surface conductive circuit 6, and the via hole. 8, back side conductive circuit 7, inner layer through hole 3,
The operation is performed to the front surface drawing circuit 4 and the rear surface drawing circuit 5, the front surface pad 1 and the rear surface pad 2, and the inner wall of the through hole 9. (A-A1-CB1-B).

2 (a) to 2 (f) are sectional views shown in the order of steps for explaining the manufacturing method of the first embodiment of the second invention.

In the manufacturing method of the first embodiment, first, as shown in FIG. 2A, an insulating plate 12 having a copper foil 11 on its surface is prepared, and a through hole 13 is formed.

Next, as shown in FIG.
The entire surface including the inner wall of 13 is subjected to ordinary catalytic treatment, electroless copper plating and electrolytic copper plating to form copper plating 14.

Next, as shown in FIG. 2 (c), the copper foil 11 and the copper plating 14 are etched on the insulating plate 12 by a normal printing-etching method, so that the surface pads 1, the back pads 2, and the inner layer through holes are formed.
3, Front drawing circuit 4, Back drawing circuit 5, Surface conductive circuit
6, and the backside conductive circuit 7 were formed at the same time, and a signal printed wiring board 20 was formed.

Next, as shown in FIG.
An electrical inspection is performed by applying an electrical inspection probe 16 from the surface of the substrate.

Next, as shown in FIG. 2 (e), double-sided printed wiring boards 20 and 21 for signal, double-sided printed wiring 22 for power ground and prepreg 19 are arranged between insulating plates 18 having copper foil 17 on one side. The laminate 15 was obtained by heat compression.

Next, as shown in FIG. 2 (f), a through-hole is provided in the through-hole portion of the laminated body 15, copper plating is performed on the entire surface by the same method as in FIG. 2 (b), and the surface is printed. Etching to form the through-hole 9 and the outermost circuit 10;
A multilayer printed wiring board 30 was obtained.

The multilayer printed wiring board 30 thus obtained has no burr generated between the double-sided printed wiring board for signal and the through-hole of the double-sided printed wiring board for signal when the through-hole is broken by a drill. As a result, a good shape of the through-hole and a good connection shape between the through-hole and the pads on the front and back layers of the double-sided signal board were obtained.

The second embodiment of the first invention is the same as the first embodiment of the first invention except that the front surface pad 1 and the back surface pad 2 in FIG. 1A are not circular but square or polygonal. A multilayer printed wiring board having exactly the same structure as that of the embodiment and having the same manufacturing method was obtained, but burrs were generated in the through-holes as in the first embodiment of the first invention. Not,
Good through-hole shape and connection shape were obtained.

〔The invention's effect〕

As described above, the present invention provides front and back pads at a connection portion with a through through hole when wiring between through through holes of a multilayer printed wiring board is performed by an inner double-sided printed wiring board. By performing wiring on the front and back with the nearby through hole as a base point, it is possible to prevent the occurrence of burrs due to the breakage of the inner layer through hole of the inner layer double-sided printed wiring board by drilling through holes, There is an effect that the electrical inspection can be easily performed only by applying the probe from the front or the back.

Further, since the connection with the through-hole is made by both the front surface pad and the back surface pad, there is an effect that the reliability of the connection can be greatly improved.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (c) are a plan view and a sectional view of a double-sided printed wiring board for signals according to a first embodiment of the first invention, and a double-sided printed wiring board for signals is incorporated in a multilayer printed wiring board. FIGS. 2A to 2F are cross-sectional views of a multilayer printed wiring board for explaining the situation.
FIGS. 6A to 6C are cross-sectional views illustrating a manufacturing method according to a first embodiment of the present invention in a process order. DESCRIPTION OF SYMBOLS 1 ... Front pad, 2 ... Back pad, 3 ... Inner layer through hole, 4 ... Front drawing circuit, 5 ... Back drawing circuit, 6 ... Front conductive circuit, 7 ... Back conductive circuit, 8
... via hole, 9 ... through through hole, 10 ... outermost layer circuit, 11 ... copper foil, 12 ... insulating plate, 13 ... through hole, 14
…… Copper plating, 15… Laminated body, 16… Electric inspection pro
, 17 ... copper foil, 18 ... insulating plate, 19 ... prepreg, 2
0,21 ... double-sided printed wiring board for signal, 30 ... multilayer printed wiring board.

Claims (2)

(57) [Claims] 1. A connection for electrically connecting pads on both front and back surfaces of an electric connection portion with a through hole of a double-sided printed wiring board on the inner layer, and the pads on both front and back surfaces of the double-sided printed wiring board in the vicinity of the pad. A multilayer printed wiring board, comprising: an inner layer through-hole; and wiring between the pad and the inner / lower side through hole for front / back connection on both the front and back surfaces of the double-sided printed wiring board. 2. A method of manufacturing a multilayer printed wiring board in which a plurality of double-sided printed wiring boards are laminated and then a through hole and an outer layer circuit are formed, comprising the following steps: Method. (A) a step of providing a through hole in an insulating plate having copper foils on both sides and then performing copper plating on the entire surface to form a conductor layer; (b) printing and etching the conductor layer on the surface of the insulating plate;
A step of forming an inner layer through-hole and a conductive circuit on both front and back sides to form a double-sided printed wiring board for signals; (c) in the step of forming the double-sided printed wiring board for signals,
A step of arranging pads on both front and back surfaces of a portion to be electrically connected to the through through hole, arranging the inner layer through hole near the pad, and arranging wiring on both front and back surfaces between the pad and the inner layer through hole (D) a step of electrically inspecting the conductive circuit of the signal double-sided printed wiring board; (e) printing and etching of an insulating plate copper foil having the same foil on both front and back surfaces to form a power ground double-sided printed wiring board; Step (f) A copper foil or an insulating plate having a copper foil formed on one side is arranged on an outer layer with the copper foil on the outside, and the double-sided printed wiring board for signal and the double-sided printed wiring board for power ground are heated by a plurality of prepregs. Step of forming a laminate by pressure bonding (g) After providing a through-hole in the laminate, performing copper plating on the entire surface to form a surface conductor layer, and then printing the surface conductor layer.
Etching to form a through-hole and the outermost layer circuit on the surface to obtain a multilayer printed wiring board