JPH0669656A - Manufacturing method of multilayer printed wiring board using component having lead wire for continuity - Google Patents

Abstract

PURPOSE:To provide a highly reliable multilayered printed wiring board manufacturing method by which soldering can be easily and accurately performed in a through hole connecting circuits to each other by piling up outer-layer printed boards and fixing the boards to each other. CONSTITUTION:The outside diameters of the connection lands 12 and 13 of the inner-layer printed wiring board 30 of inner- and outer-layer printed wiring boards 30, 40, and 50 are made larger than the diameters of the through holes 17 and 18 of the connection lands 14 and 15 of the boards 40 and 50 and, at the same time, the diameters of the holes 16, 17, and 18 are made larger on the boards 40 and 50 sides against the board 30 side. In addition, the boards 30, 40, and 50 are piled up and fixed to each other with a plurality of screws 20. Then, after installing a conical lead wire 20 for continuity composed of a plurality of thin wires 21 in the each hole 16, 17, and 18, the holes 16, 17, and 18 are filled up with solder 22 by utilizing the capillary actions of the wires 21 so as to electrically connect the boards 30, 40, and 50 to each other. Thus the title board is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art In recent years, with the increase in the density of printed wiring circuits and the miniaturization of printed wiring boards themselves,
In order to meet the demand, a printed wiring board has been developed from a double-sided board to a multilayer board and has been put into practical use.

However, in the manufacture of a multilayer printed wiring board, the inner layer forming, laminating, through-hole, exterior forming and subsequent steps shown in FIG. 4 are carried out.

[0004]

According to the method for manufacturing a multilayer printed wiring board described above, when laminating each layer, a prepreg or an adhesive is used between the layers, and complicated processing such as heating and pressing is performed. Has been given.

Further, as a means for conducting each layer, a connection method via a through hole is adopted, and
Usually, the method of conducting is performed by through-hole plating, that is, electroless copper plating and electrolytic copper plating.

However, in such a method for manufacturing a multilayer printed wiring board, the lamination process is complicated, and in the method using through-hole plating, the plating apparatus itself is large-scaled, so that the equipment cost increases and at the same time the working environment is increased. Unfortunately, there are many strict requirements for the management of the plating solution itself and many environmental problems such as wastewater treatment. Therefore, an object of the present invention is to provide a method for manufacturing a multilayer printed wiring board which can solve the above problems.

[0007]

In order to achieve the above object, the present invention is to stack printed wiring boards, and to provide a required circuit of each printed wiring circuit through a through hole formed in each printed wiring board. In a method for manufacturing a multilayer printed wiring board that is electrically connected, among the printed wiring boards that form each of the layers, the outer diameter of the connection land of the printed wiring board located in the inner layer is connected to the printed wiring board located in the outer layer. The inner diameter of the through hole formed in each printed wiring board is larger than that of the inner layer side, and the inner layer printed wiring board and the outer layer printed wiring board are overlapped to form a plurality of holes. The printed wiring boards are laminated by fixing them with screws, and the conical conductors consisting of multiple thin wires are placed in the through holes of the laminated printed wiring board. After charging the use lead wires, filled with solder by capillary action of the thin line in the through hole, characterized in that to produce the required circuit of the printed circuit plates are electrically connected.

[0008]

According to the method of forming a part having a lead wire for conduction and the through hole and the printed wiring board of the present invention, an inner layer printed wiring in which printed wiring circuits are formed on the front and back surfaces of a substrate can be used as a method of molding the printed wiring board. Since the printed wiring boards are laminated by stacking the board and the outer printed wiring board having the printed wiring circuit formed on one surface of the board and fixing the printed wiring boards with screws, each layer can be easily fixed.

Further, in order to electrically connect a required circuit of each printed wiring circuit through a through hole formed in each printed wiring board, a lead wire for conduction formed in a conical shape by a thin wire is provided in the through hole. Since it is charged into the through hole, it is possible to suck the solder into the through hole and fill the through hole by the capillary phenomenon of the thin wire.

Further, since the lead wire for conduction having a conical shape has a thin tip, it can be easily inserted into the through hole, and the conical surface surely contacts the connection land in the through hole, and It is hard to come off.

As described above, it is possible to provide a multilayer printed wiring board which has a simple lamination method, solves various drawbacks caused by through-hole plating, and has a low cost and high reliability.

[0012]

1 is a partially enlarged sectional view of a multilayer printed wiring board showing an embodiment of the present invention. The printed wiring circuits 4, 5, 6, and 7 are formed on the front and back surfaces of the inner layer substrate 1 and on one surface of the outer layer substrates 2 and 3 by a normal method.

Connection lands 12, 13, 14 and 15 for electrically connecting the required wiring circuits to each other are formed on the inner layer substrate 1 and the outer layer substrates 2 and 3, respectively. Through holes 16, 17, and 18 are drilled in the central portions of 13, 14, and 15 by a method such as drilling.

Then, the connecting lands 12, 13, 14,
The inner layer printed wiring board 30 and the outer layer printed wiring board 40 are subjected to steps such as outer diameter processing, surface treatment, and flux application, except for the surface of 15 where the solder is welded, and solder resists 8, 9, 10, 11 and marking are applied. And 50 are formed. The through holes 16, 17, 18
Makes the diameters of the through holes 17, 18 on the outer printed wiring boards 40 and 50 side larger than the diameter of the through holes 16 on the inner printed wiring board 30 side.

The inner layer printed wiring board 3 having the above structure
0 and the outer layer printed wiring boards 40 and 50 are superposed, and fixed by a plurality of screws 20 through a plurality of reference holes 19 formed in each of the printed wiring boards 30, 40 and 50, respectively. The plate 60 is formed.
The numbers of the plurality of reference holes 19 and the plurality of screws 20 are not limited.

In the through holes 16, 17, 18 of the multilayer printed wiring board 60 laminated as described above, a lead wire 29 for conduction is formed in a conical shape with a plurality of fine wires 21 made of a conductive material such as copper. Is charged and the multilayer printed wiring board 60 is dipped in a solder bath (not shown) filled with molten solder, so that the solder 22 is separated by the capillary phenomenon of the lead wire 29 for conduction which forms a conical shape with a plurality of thin wires. It is sucked into the through holes 16, 17, and 18.

As shown in FIG. 2, the conductive lead wire 29 forming the conical shape is formed on the left and right surfaces of the main body portion 27 made of an insulating material such as ceramics or resin.
The wires 28 made of conductors are inserted independently so that their ends do not contact (conduct) with each other.

The other end is bent downward and the lead wire 29 for conduction is formed at the tip of the other end so that the lead wire 29 for conduction is formed.
And a component 25 having

The conducting lead wire 29 has, for example, a small-diameter end located at the tip end of 0.5 mmΦ, a large-diameter end located at the other end of 1.0 mmΦ, and a length of 2,0 to 3,5.
A thin wire 21 that has a conical shape of mm and forms a conical shape.
Is smaller than the diameter of the through holes 16, 17, and 18, for example, if the diameter of the through hole 16 is 0.8 mm, the diameter of the thin wire 21 is about 50 to 100 μmΦ, and the surface thereof is flux treated. However, it is preferable that a large number of fine wires 21 are gathered to form a conical shape, and
It is easy to insert it inside 6, 17, and 18. As the thin wire 21, the product name "Wicking Wire CP-
1515 "(manufactured by Taiyo Sangyo Co., Ltd.) can be used.

The number of wires 28 fixed to the main body portion 27 may be a plurality of wires such as two wires or three wires,
As an example thereof, FIG. 3 shows a component 26 in which three wires 28 are fixedly mounted on the lower surface of a main body portion 27 and a lead wire 29 for conduction is provided at each end.

The molten solder in the solder bath is about 260
The temperature is maintained at ° C, and soldering is performed by immersing the multilayer printed wiring board 50 for about 5 seconds (immersion time within a range that prevents thermal damage).

Then, when the multilayer printed wiring board 60 is pulled out from the solder bath, the situation in which soldering is completed to each land portion through the through holes 16, 17 and 18 is as follows.
As shown in FIG. 1, due to the capillary phenomenon of the thin wire 21, the solder 22 is sufficiently spread inside the through holes 16, 17, 18 and is welded to the surfaces of the connection lands 12, 13 and at the same time, Solder 22 forms raised shapes 23 and 24 on the surface and is welded and solidified so that required wiring circuits of printed wiring boards 30, 40 and 50 are electrically connected to each other through through holes 16, 17, and 18. It is possible to manufacture the multilayer printed wiring board 60 that is electrically connected.

The diameters of the through holes 16, 17, 18 are larger on the outer layer printed wiring board 40, 50 side than on the inner layer printed wiring board 30 side. By increasing the exposed area of the connection lands 12 and 13 between layers, the connection area is conventionally limited by the thickness of the copper foil of each circuit (in the case of connection by through hole plating). This facilitates soldering to the surfaces of the connection lands 12, 13.

According to this embodiment, the multilayer printed wiring board 6
In the laminating method of 0, since no prepreg or adhesive is used as in the conventional case, laminating can be performed by a simple fixing method without performing heating and pressure processing with a hot plate.

The conducting lead wire 29 of the present invention is also used.
Since the parts 25 and 26 having the same shape have the same shape as the current mounted parts and the length of each lead wire 21 can be made to correspond to the design grid of 2,54 mm, or the pitch of general parts, It can be mounted by a mounting machine, and since the conducting lead wire 29 has a conical shape, it can be easily inserted into the through holes 16, 17, and 18, and the lead wire 29 surely contacts different land diameters. It is hard to come out with.

Further, since it is easy to fill the inside of the through holes 16, 17 and 18 with the solder 13 and to easily solder the surfaces of the connection lands 12 and 13 located in the through holes 16, As a result, the reliability of conduction can be improved.

By using the soldering method of the present invention as a method of electrically connecting through the through holes 16, 17, 18, the facility cost is reduced and the work environment and management are reduced when the conventional plating method is used. It is possible to solve the problems of environmental improvement and environmental hygiene.

[0028]

According to the method for manufacturing a multilayer printed wiring board of the present invention, it is possible to simplify the manufacturing of this type of printed wiring board, reduce the cost, and improve the reliability of the product.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a multilayer printed wiring board according to a manufacturing method of the present invention.

FIG. 2 is an explanatory diagram of a component having a lead wire for conduction according to the present invention.

FIG. 3 is an explanatory view showing another example of a component having a conduction lead wire.

FIG. 4 is an explanatory view showing a conventional method for manufacturing a multilayer printed wiring board.

[Explanation of symbols]

 1 Inner layer board 2, 3 Outer layer board 4, 5, 6, 7 Printed wiring circuit 8, 9, 10, 11 Solder resist 12, 13, 14, 15 Connection land 16, 17, 18 Through hole 19 Jig hole 20 Screw 21 Fine Wire 22 Solder 23, 24 Raised Shape 26 Components with Lead Wire for Conduction 27 Main Body 28 Wire 29 Lead Wire

Claims (1)

[Claims] 1. Laminating each printed wiring board,
In a method for manufacturing a multilayer printed wiring board, in which a required circuit of each printed wiring circuit is electrically connected through a through hole formed in each printed wiring board, in each printed wiring board forming each layer, an inner layer is formed. The outer diameter of the connecting land of the printed wiring board located is made larger than the through hole diameter of the connecting land of the printed wiring board located in the outer layer, and the inner diameter of the through hole drilled in each printed wiring board is larger than that of the inner layer side from the outer layer side. The side is enlarged, and the inner layer printed wiring board and the outer layer printed wiring board are superposed and fixed by a plurality of screws to be laminated, and further, a plurality of thin wires are formed in the through holes of the laminated printed wiring board. After inserting a conical lead wire for conduction, fill the through hole with solder by the capillary phenomenon of the thin wire, Method for manufacturing a multilayer printed wiring board using a component having a conductive lead wires, characterized in that to produce electrically connecting the required circuit wiring plates.