JPH1079575A - Printed wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control conductive paste in amount for filling it uniformly into through-hole which are densely disposed so as to improve conduction holes in reliability by a method, wherein voids are provided to a conductor circuit or a land pattern adjacent to the densely disposed through-holes and varied in size. SOLUTION: Voids 6a are provided to land patterns 5, adjacent to the inner circumferences of through-holes 4a to 4c respectively, and other voids 6b of prescribed size are provided onto the land patterns 5. The voids 6a and 6b provided to the through-holes 4a to 4c are lessened in number and area in a printing direction S. Concentric voids 6c to 6e are provided adjacent to the through-holes 4a to 4c, so as to adjust the amount of sliver paste filled into the through-holes 4a to 4c. By this setup, even if silver paste is excessively discharged, silver paste which is filled into the through-holes 4a to 4c can be controlled in amount by varying voids in size, so that nonconformity of billing solved can be.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board used for various electronic devices and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, printed wiring boards, which are widely used in various electronic devices and the like, have been required to have higher wiring density and higher reliability as electronic devices have become smaller and more multifunctional. ing. In particular, in recent years, there has been a remarkable demand for improved productivity and cost reduction of printed wiring boards, and copper through-holes for interlayer connection by electrolytic copper plating have been used to fill the through holes with silver paste as a conductive material from printed wiring boards. A so-called silver through-hole printed wiring board for performing interlayer connection has attracted attention.

A conventional silver through-hole printed wiring board will be described below with reference to the drawings. 4 (a) to 4 (c)
FIGS. 5A and 5B are cross-sectional views illustrating a method for manufacturing a conventional silver through-hole printed wiring board, and FIGS. 5A and 5B are cross-sectional views illustrating problems of the conventional silver through-hole printed wiring board. FIG.
5A and 5B, 21 is a printed wiring board, 22 is a base material, 23 is a conductor circuit, and 24a to 24c.
24c is a through hole, 25 is a land pattern for both-side conduction,
26 is a solder resist, 27 is a silver paste, 28 is a conduction hole, 29 is a silver land, 31 is an insulating film, 32 is a small diameter defect of the silver land 29, 33 is a defective filling of the silver paste 27, 3
4 indicates that the silver land 29 does not protrude.

[0004] First, copper foil is laminated on both surfaces of the base material 22 and through holes 24a to 24c are formed by drilling in a substrate cut to a predetermined size, and then etched as shown in FIG. The land pattern 25 and the conductive circuit 23 are formed by resist printing and copper foil etching, and the printed wiring board 21 on which the solder resist 26 is formed to protect the conductive circuit 23 is obtained. Next, as shown in FIG. 4B, a silver paste 27 containing silver powder, an epoxy resin and a curing agent as main components is applied on the land pattern 25 and through holes 24a to 24a.
24c is printed and filled, and the silver paste 27 is heated and hardened in a hot air furnace to form a conduction hole 28 and a silver land 29. Thereafter, as shown in FIG. 4C, an insulating film 31 for preventing migration of silver is formed on the exposed conductive holes 28 on the land pattern 25 and the silver lands 29.

[0005]

In the manufacture of a printed circuit board having silver through holes, if there are continuously dense through holes 24a to 24c provided in a power supply circuit or an earth circuit portion, the through holes 24a to 24c are formed. The filling amount of the silver paste 27 in the printing direction S tends to be insufficient due to a shortage in the printing direction S, and quality such as a small diameter defect 32 of the silver land 29 and a defective filling 33 of the silver paste 27 as shown in FIG. An unstable state occurs, and in an extreme case, the resistance value increases. In order to solve this problem, there has been a method in which a printing jig or a printing bed of a printing press is conventionally improved and a printing pressure is adjusted at the time of filling for printing.
Conversely, when the filling amount was increased, a defective protrusion 34 of the silver land 29 as shown in FIG. 5 (b) occurred, and the silver land 29 was not completely eliminated.

Further, as disclosed in Japanese Patent Application Laid-Open No. 7-99376, a method has been proposed in which the diameter of through holes that are continuously dense is changed to adjust the filling amount of silver paste into the through holes. It was not a preferable method for dealing with the wiring design of a silver through-hole printed wiring board.

[0007] As a means for solving the problem of printing and filling the continuous dense through-holes in the above-mentioned conventional method for manufacturing a printed wiring board, the above-mentioned method such as examination of printing conditions and ink has been considered. Is difficult to control as desired, and has not been completely solved.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and solves the problem of filling of a conductive paste into a continuous densely packed through hole in the production of a printed wiring board by filling with a conductive material. It is an object of the present invention to provide a high-quality and highly reliable printed wiring board.

[0009]

SUMMARY OF THE INVENTION In order to achieve this object, the present invention provides a printed circuit board in which a conductive circuit and a land pattern are formed, a conductive paste is printed and filled in a through hole, and both sides are electrically connected. A notch is provided in the conductor circuit or land pattern near the through hole provided by
The size of the missing portion is changed. With this configuration, a printed circuit board having a high-quality conductive hole can be obtained by printing and filling the conductive circuit or the land pattern and the through hole with the conductive paste.

[0010]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, a printed circuit board in which a conductive circuit and a land pattern are formed, a conductive paste is printed and filled in a through-hole, and both sides of the printed circuit board are electrically connected. The printed circuit board is characterized in that a cutout portion is provided on a conductor circuit or a land pattern in the vicinity of the provided through hole and the size of the cutout portion is changed. The amount of the conductive paste filled in the holes is adjusted by the size of the notched portion on the conductor circuit or the land pattern, and the effect of improving the reliability of the conductive holes by eliminating non-uniform filling is achieved.

According to a second aspect of the present invention, there is provided a printed wiring board characterized in that a notch is provided in an inner peripheral portion of a conductor circuit or a land pattern, and a conductor near a through hole is provided. Providing the notched portion on the inner peripheral portion of the circuit or land pattern has an effect that the filling amount of the conductive paste in the through hole can be easily adjusted.

According to a third aspect of the present invention, there is provided a printed wiring board in which a cut portion is gradually reduced in accordance with a print filling method. By reducing the amount of the conductive paste, the filling ratio to the through-hole is increased, thereby ensuring a uniform filling amount and improving the reliability of the conduction hole.

According to a fourth aspect of the present invention, there is provided a printed wiring board in which a conductive paste is printed and filled in a through-hole of a base material having a conductive circuit and a land pattern formed on both sides and cured to form a conductive hole. In the manufacturing method, a conductive circuit or a land pattern having a cutout having a different size is provided in the vicinity of a continuously densely provided through hole, and the conductive circuit or the land pattern and the through hole are printed and filled with a conductive paste. A method of manufacturing a printed wiring board, characterized in that a conductive paste is inserted into a notched portion of a different size provided in a conductor circuit or a land pattern in the vicinity of a continuously dense through-hole to penetrate through. Adjusting the filling amount in the holes has the effect of eliminating non-uniform filling and improving the reliability of the conduction holes.

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are plan views showing a land pattern and a shape of a conductor circuit of a silver through-hole printed wiring board according to an embodiment of the present invention.
(A)-(c) is sectional drawing which shows the manufacturing method of the printed wiring board in one Embodiment of this invention.

1, 2 and 3 (a) to 3 (c), 1 is a printed wiring board, 2 is a base material, 3 is a solder resist,
4a to 4c are continuously dense through holes, 5 is a land pattern, 6a and 6b are missing portions on the land pattern 5, 6c to
6e is a cutout on the conductor circuit, 7 is a conductor circuit, 8 is a silver paste, 9a to 9c are conduction holes, 10 is a silver land, and 11 is an insulating film.

First, as shown in FIG.
Are a plurality of notches 6a in the inner peripheral portion near the through holes 4a to 4c and a plurality of notches 6b of a predetermined size on the land pattern 5.
The notched portions 6a and 6b have a configuration in which the surface of the base material 2 is exposed. In the through holes 4a to 4c which are continuously dense, the number of the cutout portions 6a and 6b decreases along the printing direction S, and the area of the cutout portions 6a and 6b on the land pattern 5 is reduced. Also, as shown in FIG. 2, concentric circles are formed near the through holes 4a to 4c provided in the conductor circuit 7 such as a power supply and a ground as shown in FIG. It is desirable to provide the removing parts 6c to 6e. The width of each of the cutouts 6c to 6e is 0.12 mm, and the width of each of the cutouts 6c to 6e is 0.1 mm.
80 mm, 0.40 mm, along the printing direction S, the notch 6 c-
6e is reduced.

Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described in detail with reference to FIGS. First, as shown in FIG. 3 (a), copper foils are laminated on both surfaces of the base material 2 and through holes 4a to 4c which are continuously densely formed by drilling on a substrate cut to a predetermined size. FIG.
An etching resist is formed and etched on the copper foil by a known screen printing method or photographic development method using a screen plate or a mask film on which a conductor circuit pattern as shown in FIG. 6
Then, the printed circuit board 1 on which the solder resist 3 is formed as the protection of the conductor circuit 7 is obtained. At this time, the conductor circuit 7 has the cutout portions 6c to 6e, and the lower surfaces of the cutout portions 6c to 6e have a structure in which the base material 2 is exposed.

Next, as shown in FIG. 3B, a silver paste 8 containing silver powder, an epoxy resin and a hardening agent as main components is slid and printed along the printing direction S into the through holes 4a to 4c which are continuously densely formed. The holes 4a to 4c are filled.

At this time, the through holes 4b and 4c which are continuously densely packed are formed.
Is one of the places where the filling amount of the silver paste 8 is insufficient in the printing direction and is likely to be non-uniform. In addition, the silver protrusion 8 that easily occurs in the through-hole 4a and the silver paste 8 penetrates into the relatively large notch 6c absorbs the excess silver paste 8 and can solve the protrusion defect. .

The through holes 4a to 4c thus continuously densely arranged
Of the silver paste 8 due to the presence of the notches 6c to 6e corresponding to
Even if the amount of coating is large, through holes 4
Since the amount of filling in a to 4c can be adjusted, non-uniform filling can be eliminated, and a uniform silver land 10 as shown in FIG. 3B can be formed.

Thereafter, as shown in FIG. 3C, the silver paste 8 is hardened in a hot-air drying oven to form conductive holes 9a to 9c and silver lands 10, thereby preventing silver migration and protecting the conductive holes 9a to 9c. Therefore, the insulating film 11 is formed on the silver land 10, and a high-quality silver through-hole printed wiring board can be obtained.

In the present invention, a method of manufacturing a silver through-hole printed wiring board is used as a reference example. However, a ceramic in which a conductive circuit is formed using a conductive copper paste on a green sheet having a through hole is used. By using the present invention in the manufacture of a substrate, it is also possible to improve the quality of the conduction hole.

[0024]

As described above, according to the present invention, when forming a pattern on a printed wiring board having silver through holes, through holes which are continuously densely formed by forming a cutout portion in a conductor circuit or land pattern near the through hole. By making the filling amount of the conductive material uniform, defects of small diameter of silver land and protrusion of silver land can be eliminated, and a high-yield, high-quality printed wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view showing the shape of a land pattern of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a plan view showing the shape of a conductor circuit of another example.

3A to 3C are cross-sectional views illustrating a method for manufacturing a printed wiring board according to an embodiment of the present invention.

FIGS. 4A to 4C are cross-sectional views illustrating a method for manufacturing a conventional silver through-hole printed wiring board.

5 (a) to 5 (c) are cross-sectional views showing problems of a conventional silver through-hole printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Base material 3 Solder resist 4a-4c Continuously dense through-hole 5 Land pattern 6a-6e Missing part 7 Conductor circuit 8 Silver paste 9a-9c Conducting hole 10 Silver land 11 Insulation coating

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[Procedure amendment]

[Submission date] November 8, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a plan view showing the shape of a land pattern of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a plan view showing the shape of a conductor circuit of another example.

3A to 3C are cross-sectional views illustrating a method for manufacturing a printed wiring board according to an embodiment of the present invention.

FIGS. 4A to 4C are cross-sectional views illustrating a method for manufacturing a conventional silver through-hole printed wiring board.

5 (a) and 5 (b) are cross-sectional views showing problems of a conventional silver through-hole printed wiring board.

DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Base material 3 Solder resist 4a-4c Continuously dense through-hole 5 Land pattern 6a-6e Missing portion 7 Conductor circuit 8 Silver paste 9a-9c Conducting hole 10 Silver land 11 Insulation coating

Claims (4)

[Claims] 1. A printed circuit board in which a conductive circuit and a land pattern are formed, a conductive paste is printed and filled in through holes, and both sides of the printed circuit board are electrically connected to each other. A printed wiring board in which a notch is provided and the size of the notch is changed. 2. The printed wiring board according to claim 1, wherein a notch is provided in an inner peripheral portion of the conductor circuit or the land pattern. 3. The printed wiring board according to claim 1, wherein the cut portion is gradually reduced along the printing filling direction. 4. A method of manufacturing a printed wiring board in which a conductive paste is printed and filled into a through-hole of a base material having a conductive circuit and a land pattern formed on both sides and cured to form a conductive hole. A method of manufacturing a printed wiring board, comprising: providing a conductor circuit or land pattern having a cutout portion having a different size in the vicinity of the through hole, and printing and filling the conductive circuit or land pattern and the through hole with a conductive paste.