JPH0369192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION The present invention relates to a method for manufacturing printed wiring boards by electroplating with over-deposited through-hole connections.

"Prior Art" In a double-sided printed wiring board, when it is necessary to connect front and back conductors, so-called through-hole connection is used. To explain this conventional method, a double-sided copper-clad board with through holes is electrolessly copper plated, copper is deposited and adhered to the through holes, and the copper foils on the front and back are short-circuited.
This technique then completes the short circuit by attaching a plating layer of copper or the like to the copper inside the through hole by electroplating.

"Problems to be Solved by the Invention" However, these conventional techniques require complicated processes and associated special chemical management during electroless plating, making it difficult to stabilize quality and reduce costs. Furthermore, in order to deposit plating in areas other than the through-hole areas, it is necessary to increase the thickness of the thin body in the part that will become the circuit, and remove excess copper by etching when forming the circuit, as well as impairing the bending performance of the copper foil in the circuit part. There was a problem.

The present invention aims to solve the problems of the prior art and to simplify the process and increase cost reduction effects.

"Means for Solving the Problems" The present invention includes a process of forming masking layers on both sides of a double-sided copper-clad board, and making a hole through the masking layer in the masked double-sided copper-clad board to form a through hole. Forming process and 2 in the through hole
A process of applying excessive electroplating by concentrating the plating metal on the ring-shaped surface of the copper foil exposed in the area, and pressing the electroplated double-sided copper-clad board in the direction of its thickness. The method for manufacturing a printed wiring board includes the step of pushing the overly attached pinning metal toward the center in the thickness direction and electrically connecting the pinning metal to each other.

In addition, with the solder attached to the plated metal, press the double-sided copper-clad board in the thickness direction to push the plated metal and solder toward the center of the thickness, and then melt the solder. This is a method for manufacturing printed wiring boards that incorporates technology to make electrical connections.

"Function" By these means, the adhesion of the plating metal concentrates on the copper foil slightly exposed in the unmasked through hole, increasing the excessive adhesion of the plating metal. The overly adhered plating metal or solder is pressed into the center of the substrate in the thickness direction and brought into electrical contact.

By melting the solder, electrical connection is induced using the surface tension of the molten solder.

"Embodiment" Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 3.

1A to 1G are diagrams showing the order of the manufacturing process of a printed wiring board, FIG. 2 is a schematic diagram showing an example of an apparatus suitable for applying the present invention, and FIG. 3 is a flowchart of the manufacturing process. .

"Material supply (S1)" A double-sided copper-clad substrate 1 whose base film 1a has a thickness of usually 200 μm or less is fed out as shown in Fig. 2, and a masking material 2 such as masking tape is fed out on both sides. .

"Masking layer forming step (S2)" These are pasted together using a pair of rolls 3 shown in FIG. 2, etc., so that masking layers 4 are formed on both sides of the double-sided copper-clad substrate 1.

"Through-hole formation process (S3)" Double-sided copper-clad substrate 1 covered with masking layer 4
A through hole 6 is formed by punching the hole using the press (punching) 5 shown in FIG. 2 or an N/C drilling machine. By forming this through hole 6, as shown in FIG. It will be exposed in two places.

"Electroplating process (S4)" Double-sided copper-clad substrate 1 covered with masking layer 4
When the substrate 1 is sent to the electroplating device 7 shown in FIG. A phenomenon occurs in which the adhesion of the plating metal 8 is concentrated on the ring-shaped surface of the copper foil 1b (the state shown in FIG. 1B). If this plating is continued, the plating metal 8 will swell in the thickness direction of the substrate 1, as shown in FIG. 1C, resulting in excessive adhesion. Furthermore, when excessive adhesion of plating metal 8 is promoted, as shown in FIG. As the phenomenon of rising outward from the through hole 6 occurs, the plating metal 8 crosses the exposed surface of the adhesive layer 1C in the through hole 6 and reaches the exposed surface of the base film 1a, as indicated by X in FIG. 1D. , the phenomenon that the top and bottom finally come into contact occurs.

``Solder plating process (S5)'' The board 1 that has been electroplated in this way is
The substrate 1 is sent to a soldering device 9 shown in the figure, and solder 10 is applied to the through holes 6 of the substrate 1. In this process, the molten solder 10 has the property of penetrating into narrow areas due to the capillary phenomenon, so even if the plating metal 8 has a gap above and below, it fills the gap and creates the state shown in FIG. 1E, for example. It can be done.

"Masking removal step (S6)" The masking layer 4 adhering to the surface of the soldered board 1 is removed by the peeling roll 1 shown in FIG.
1 to remove it from the surface of both copper foils 1b. By removing this masking layer 4,
The plating metal 8 and the solder 10 protrude vertically by the thickness thereof.

"Press step (S7)" Press the board 1 in the thickness direction using the press 12 shown in FIG. When compressed in the horizontal direction, the vertically protruding portions of the plating metal 8 and the solder 10 become
The substrate 1 is pushed into the center of the substrate 1 in the thickness direction.
Plated metal 8 and solder 1 at two locations in the thickness direction of
Copper foil 1 separated by contact with copper foil 1
b is brought into electrical connection.

"Reflow Step (S8)" The thus pressed substrate 1 is sent to the heating device 13 shown in FIG. 2, and the solder 10 is melted. Due to the surface tension in the molten state, the solder 10 can be brought into the state shown in FIG. 1G, further ensuring the electrical connection.

"Surface treatment process (S9)" After electrically connecting the upper and lower copper foils 1b, the board 1 is sent to the surface treatment device 14 shown in Fig. 2 to clean the surface of the board 1 and prepare it for the next process. After surface treatment, it is sent out.

"Pattern Forming Step (Sn)" Next, the pattern forming device 15 repeats each pattern forming step to form the required double-sided printed wiring board.

Note that each of the steps described above can also be performed using the following techniques.

In (S1), the masking material 2 is composed of dry film or liquid resist ink instead of masking tape.

In (S4), plating with plastic metal other than copper.

In (S5), instead of using a solder bath, cream solder is applied and adhered by screen printing, etc. In addition, in cases where the base film is thin, the step (S5) may be omitted as appropriate. Furthermore, a large amount of solder 10 is applied to the through hole 6.
to facilitate terminal connection or printing.

In (S8), heating is performed using ultrasonic waves or laser beams.

"Effects of the Invention" As explained above, according to the present invention, the following effects can be achieved.

Through-holes are formed with masking on both sides of a double-sided copper-clad board, and the plating metal is concentrated on the exposed copper foil at two locations inside the through-hole to perform excessive electroplating. Since the board is pressed and the overly attached plating metal is pushed toward the center of the thickness direction, the two plating metals are brought into electrical contact with each other. Electrical connection within the through hole can be achieved without requiring an electroless copper plating formation process, simplifying the process and reducing costs.

Electroplating is applied to the exposed copper foil inside the masked through-hole, so electroplating does not adhere to areas other than the through-hole, and the exposed copper foil The plating metal can be deposited in a concentrated manner, and an excess of the plating metal can be quickly deposited.

Furthermore, by depositing the plating metal in a concentrated manner, the plating power source can be made of a small capacity.

By adding a method to make an electrical connection by pressing the plated metal and solder toward the center of the thickness with the solder attached to the plated metal, and then melting the solder. , it is possible to further improve the electrical connectivity of the copper foils that were spaced apart in the through hole.

[Brief explanation of drawings]

1A to 1G are diagrams showing the order of the manufacturing process of a printed wiring board, FIG. 2 is a schematic diagram showing an example of an apparatus suitable for applying the present invention, and FIG. 3 is a flowchart of the manufacturing process. . DESCRIPTION OF SYMBOLS 1...Double-sided copper-clad board, 1a...Base film, 1b...Copper foil, 1c...Adhesive layer, 4...Masking layer, 6...Through hole, 8...Plated metal, 10...Solder.

Claims (1)

[Claims] 1. A step of forming masking layers 4 on both sides of the double-sided copper-clad substrate 1, and a step of forming a through-hole 6 in the masked double-sided copper-clad substrate by making a hole through the masking layer. , a step of applying excessive electroplating by intensively attaching plating metal 8 to the ring-shaped surface of the copper foil 1b exposed at two places in the through hole, and a process of applying electroplating to the double-sided copper cladding. A method for manufacturing a printed wiring board, comprising the step of pressing a board in its thickness direction to push the excessively attached mating metal toward the center in the thickness direction and electrically connecting the mating metals to each other. 2 With the solder 10 attached to the plating metal 8, press the double-sided copper-clad board in the thickness direction to push the plating metal and solder toward the center of the thickness, and then melt the solder. 2. The method of manufacturing a printed wiring board according to claim 1, wherein the printed wiring board is electrically connected by connecting the wires to each other.