JP3794064B2 - Printed wiring board and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board used for various electronic devices and a manufacturing method thereof.
[0002]
[Prior art]
2. Description of the Related Art In recent years, printed wiring boards that are widely used in various electronic devices and the like have been required to have high reliability along with higher wiring density as electronic devices have become smaller and more multifunctional. In particular, the demand for improved productivity and cost reduction of printed wiring boards has been remarkable in recent years. By filling the through-holes with silver paste as a conductive material from copper through-hole printed wiring boards that achieve interlayer connection by electrolytic copper plating A so-called silver through-hole printed wiring board that performs interlayer connection has attracted attention.
[0003]
A conventional silver through-hole printed wiring board will be described below with reference to the drawings.
FIGS. 4A to 4C are cross-sectional views showing a conventional method for producing a silver through-hole printed wiring board, and FIGS. 5A and 5B show problems of the conventional silver through-hole printed wiring board. It is sectional drawing. 4 (a) to 4 (c) and FIGS. 5 (a) and 5 (b), 21 is a printed wiring board, 22 is a base material, 23 is a conductor circuit, 24a to 24c are through holes, and 25 is a land for double-sided conduction. Pattern, 26 is a solder resist, 27 is a silver paste, 28 is a conduction hole, 29 is a silver land, 31 is an insulating coating, 32 is a small diameter defect of the silver land 29, 33 is a poor filling of the silver paste 27, and 34 is a silver land 29 Is not protruding.
[0004]
First, after copper holes are laminated on both surfaces of the base material 22 and through holes 24a to 24c are provided by drilling on a substrate cut to a predetermined size, etching resist printing and printing are performed as shown in FIG. The land pattern 25 and the conductor circuit 23 are formed by etching the copper foil, and the printed wiring board 21 on which the solder resist 26 is formed as a protection of the conductor circuit 23 is obtained. Next, as shown in FIG. 4B, the silver paste 27 mainly composed of silver powder, epoxy resin and curing agent is printed and filled on the land pattern 25 and the through holes 24a to 24c, and the silver paste 27 is heated in a hot air oven. The conductive hole 28 and the silver land 29 are formed by curing. Thereafter, as shown in FIG. 4C, an insulating film 31 for preventing silver migration is formed on the exposed conduction holes 28 on the land pattern 25 and the silver lands 29.
[0005]
[Problems to be solved by the invention]
In the production of the silver through hole printed wiring board, when there are continuously dense through holes 24a to 24c provided in the power supply circuit and the earth circuit part, the filling of the through holes 24a to 24c with respect to the printing direction S is performed. The amount of filling of the silver paste 27 is insufficient and tends to be non-uniform, resulting in an unstable quality state such as a small diameter defect 32 of the silver land 29 and a filling defect 33 of the silver paste 27 as shown in FIG. In extreme cases, the resistance value increased. In order to solve this problem, there has been a conventional method in which the printing jig and the printing bed of the printing machine are improved and the printing pressure is adjusted at the time of filling the printing. However, if the filling amount of the silver paste 27 is increased, conversely, As shown in FIG. 5B, the protrusion 34 of the silver land 29 occurred, and it was not completely eliminated.
[0006]
Further, as disclosed in Japanese Patent Laid-Open No. 7-99376, a method for adjusting the filling amount of the silver paste into the through holes by changing the hole diameter of the continuously dense through holes has been proposed. It cannot be said that it is a preferable method in the correspondence in the wiring design with the hall printed wiring board.
[0007]
Although the above-mentioned methods such as the examination of printing conditions and ink have been considered as means for solving the problems in the printing and filling of the continuous dense through holes in the conventional method for producing a printed wiring board, an ink coating amount is desired. Thus, it was difficult to control and was not completely solved.
[0008]
The present invention solves the above-mentioned conventional problems, eliminates the problem of filling the conductive paste into the continuous densely packed through-holes in the production of printed wiring boards, eliminates the problem of filling the conductive paste, and is inexpensive, high quality and An object of the present invention is to provide a printed wiring board having excellent reliability.
[0009]
[Means for Solving the Problems]
In order to achieve this object, the present invention provides a printed circuit board in which conductor circuits and land patterns are formed, conductive paste is printed and filled in through holes, and both sides are electrically connected to a power circuit and a ground conductor circuit. A notch is provided in the inner periphery of the conductor circuit or land pattern in the vicinity of the formed through hole, and the size of the notch is changed. With this configuration, it is possible to obtain a printed wiring board having a high-quality conduction hole by printing and filling a conductive paste in a conductor circuit or a land pattern and a through hole.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, in the printed wiring board conductive duplex print filling conductive paste into the through-hole to form a conductor circuit and land patterns, continuous densely the conductive circuits of the power and ground provided lacking portion on the inner peripheral portion of the conductive circuit or land patterns in the vicinity of the provided through hole, which has a printed circuit board with varying size of the cut-off parts, lacking the inner peripheral portion By providing a section, the filling amount of the conductive paste in the densely packed through holes can be adjusted by the size of the notch on the conductor circuit or land pattern, and the filling amount of the conductive paste in the through holes can be easily adjusted. Therefore, the non-uniform filling is eliminated and the reliability of the conduction hole is improved .
[0011]
According to a second aspect of the present invention, in a printed wiring board in which a conductor circuit and a land pattern are formed, a conductive paste is printed and filled in a through-hole, and both sides are electrically connected, the conductor circuit is continuously concentrated on a power supply or ground conductor circuit. A printed circuit board is provided in which a notched portion is provided in a conductor circuit or land pattern in the vicinity of the provided through hole, and the size of the notched portion is gradually reduced in the print filling direction . By reducing the amount of conductive paste that enters the missing portion along the printing filling direction, increasing the filling ratio to the through holes ensures a uniform filling amount and improves the reliability of the conduction holes Has an effect .
[0012]
According to a third aspect of the present invention, there is provided a printed wiring board manufacturing method in which a conductive paste is printed and filled in a through hole of a base material having a conductor circuit and a land pattern formed on both sides and cured to form a conductive hole. A conductor circuit or land pattern having a cut-out portion having a different size is provided on the inner peripheral portion in the vicinity of a through-hole provided continuously and densely in a power supply or ground conductor circuit, and the conductor circuit or land pattern and through-hole are provided. It is a method for manufacturing a printed wiring board in which a conductive paste is printed and filled, and in the lacking portions of different sizes provided in the inner periphery of the conductor circuit or land pattern in the vicinity of the densely packed through holes, By having the conductive paste enter, the filling amount in the through hole is adjusted, thereby eliminating the non-uniform filling and improving the reliability of the conduction hole .
[0013]
According to a fourth aspect of the present invention, there is provided a printed wiring board manufacturing method in which a conductive paste is printed and filled in a through hole of a base material having a conductor circuit and a land pattern formed on both sides thereof and cured to form a conductive hole. A conductor circuit or land pattern having a notch portion gradually reduced in size in the print filling direction is provided in the vicinity of a through-hole provided continuously and densely in a power supply or ground conductor circuit; land patterns and are in a conductive paste into the through-hole that the method for manufacturing a printed wiring board to be printed and filled, size toward the printing filling direction provided in the conductor circuit or land patterns in the vicinity of the through holes continuous dense By adjusting the filling amount in the through-hole by inserting the conductive paste into the cut-out part where the diameter is gradually reduced, the non-uniform filling is eliminated. It has the effect of improving the reliability.
[0014]
(Embodiment 1)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0015]
1 and 2 are plan views showing the land pattern and the shape of a conductor circuit of a silver through-hole printed wiring board according to one embodiment of the present invention, and FIGS. It is sectional drawing which shows the manufacturing method of the printed wiring board in embodiment.
[0016]
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 continuous dense through holes, 5 is a land pattern, 6a and 6b Is a notch on the land pattern 5, 6c to 6e are notches 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. .
[0017]
First, as shown in FIG. 1, the land pattern 5 is configured by providing a plurality of notched portions 6 a on the inner peripheral portion in the vicinity of the through holes 4 a to 4 c and a plurality of notched portions 6 b having a predetermined size on the land pattern 5. In addition, the lacking portions 6a and 6b are configured such that the surface of the base material 2 is exposed. The through-holes 4 a to 4 c that are continuously densely packed have a reduced number of the notched portions 6 a and 6 b along the printing direction S, thereby reducing the areas of the notched portions 6 a and 6 b on the land pattern 5. In addition, as a shape that allows easy adjustment of the filling amount of the silver paste 8 in the through holes 4a to 4c, a concentric circle is not formed in the vicinity of the through holes 4a to 4c provided in the conductor circuit 7 such as a power source or ground as shown in FIG. It is desirable to provide the removal parts 6c-6e. The widths of the notched portions 6c to 6e are 0.12 mm, 0.80 mm, and 0.40 mm, respectively, and the areas of the notched portions 6c to 6e are reduced along the printing direction S.
[0018]
Hereinafter, the manufacturing method of the printed wiring board of this invention is demonstrated in detail using Fig.3 (a)-(c). First, as shown in FIG. 3 (a), after copper foil is laminated on both surfaces of the base material 2 and the through holes 4a to 4c that are continuously densely formed by drilling are formed on a substrate cut to a predetermined size, Using a screen plate or mask film on which a conductor circuit pattern as shown in FIG. 3B is drawn, an etching resist is formed and etched on the copper foil by a known screen printing method or a photographic development method. The printed circuit board 1 having the conductor circuit 7 having 6c to 6e and forming the solder resist 3 as the protection of the conductor circuit 7 is obtained. At this time, the conductor circuit 7 has the notched portions 6c to 6e, and the lower surface of the notched portions 6c to 6e has a structure in which the base material 2 is exposed.
[0019]
Next, as shown in FIG. 3 (b), silver paste 8 mainly composed of silver powder, epoxy resin, and curing agent is slidingly printed along the printing direction S in the through holes 4a to 4c that are continuously densely packed. Fill 4c.
[0020]
The filling of the through holes 4b and 4c, which are continuously dense at this time, is one of the places where the filling amount of the silver paste 8 is insufficient with respect to the printing direction and is likely to be non-uniform. 8 is increased more than usual to eliminate the small-diameter defect of the silver land 10 and the silver protruding defect which is likely to occur in the through hole 4a enters the relatively large notch 6c. Absorbs and can eliminate overhang defects.
[0021]
In this way, even when the amount of silver paste 8 applied is large due to the presence of the notched portions 6c to 6e corresponding to the densely packed through holes 4a to 4c, the filling amount to the through holes 4a to 4c depends on the size of the notched portion. Therefore, the nonuniformity of filling can be eliminated, and a uniform silver land 10 as shown in FIG. 3B can be formed.
[0022]
Thereafter, as shown in FIG. 3 (c), the silver paste 8 is hardened in a hot air drying furnace to form conduction holes 9a to 9c and silver lands 10, and silver land is used to prevent silver migration and protect the conduction holes 9a to 9c. An insulating coating 11 can be formed on 10 to obtain a high-quality silver through-hole printed wiring board.
[0023]
In addition, although the manufacturing method of the silver through-hole printed wiring board was used as a reference example in this invention, manufacture of the ceramic substrate which forms a conductive circuit and a conduction hole using a conductive copper paste on the green sheet which has a through-hole Also in this case, it is possible to improve the quality of the conduction hole by using the present invention.
[0024]
【The invention's effect】
As described above, the present invention provides a conductive material for through-holes that are continuously densely formed by forming a notch in a conductor circuit or land pattern in the vicinity of the through-hole when forming a pattern of a printed wiring board having silver through-holes. By making the filling amount uniform, it is possible to eliminate the small diameter defect of the silver land and the protrusion defect of the silver land, and to provide a high-quality printed wiring board with a high yield.
[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. c) Cross-sectional view showing a method for manufacturing a printed wiring board in an embodiment of the present invention. [FIG. 4] (a) to (c) Cross-sectional views showing a method for manufacturing a conventional silver through-hole printed wiring board. (A) , (b) Cross-sectional view showing problems of 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 Deletion part 7 Conductor circuit 8 Silver paste 9a-9c Conduction hole 10 Silver land 11 Insulation film

Claims (4)

In a printed wiring board in which a conductive circuit and a land pattern are formed and a conductive paste is printed and filled in the through hole and both sides are conductive, the conductor circuit or land in the vicinity of the through hole provided in a densely packed state in the power supply or ground conductor circuit A printed wiring board in which a notched portion is provided on the inner periphery of the pattern and the size of the notched portion is changed. In a printed wiring board in which a conductive circuit and a land pattern are formed and a conductive paste is printed and filled in the through hole and both sides are conductive, the conductor circuit or land in the vicinity of the through hole provided in a densely packed state in the power supply or ground conductor circuit A printed wiring board in which a notch is provided in a pattern, and the size of the notch is gradually reduced in the print filling direction . The method for manufacturing a printed wiring board to form the through hole with a conductive paste into the through hole of the base material forming a conductor circuit and land patterns on the double-sided printing filled cured to continuously densely the conductive circuits of the power and ground in the vicinity of the provided through-holes, the inner peripheral portion of the conductor circuit or land patterns having different lack portion sizes provided in the conductor circuit or land patterns and the through holes of the printed circuit board to print filled with a conductive paste Production method. The method for manufacturing a printed wiring board to form the through hole with a conductive paste into the through hole of the base material forming a conductor circuit and land patterns on the double-sided printing filled cured to continuously densely the conductive circuits of the power and ground Provide a conductor circuit or land pattern with a cutout part that gradually decreases in size in the print filling direction in the vicinity of the provided through hole, and print and fill the conductor circuit or land pattern and the through hole with conductive paste. A printed wiring board manufacturing method.

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