JPS59112693A - Method of plating printed board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to surface treatment in the manufacturing process of printed circuit boards used in electronic devices, etc., and particularly relates to a method of plating inside through-holes to be peeled. It is something.

(2) Background of the technology Printed circuit boards that must be densely packed with dense circuit networks and small, highly integrated components are made up of multiple layers of fine conductor patterns, and the conductor patterns in each layer are connected by through-hole plating. However, the perforation density of through-hole plating is high, the perforation diameter is small, and the perforation length is small, so the connectivity of the through-hole plating of such printed circuit boards is the main factor for the reliability of printed circuit board packages. Therefore, there is a need for a plating method that can provide high-quality through-hole plating.

(3) Prior Art and Problems FIG. 1 is a cross section of a printed circuit board on which through holes are to be formed, and FIG. 2 is a side view for explaining a conventional through hole plating method for a printed circuit board.

In Figure 1, 1 is a printed circuit board, 2 is a conductor pattern,
3 is a through hole for through hole coating. 4 is a through hole plating inside the through hole.

In FIG. 2, 5 is a plating tank, 6 is a plating solution, 7 is a transfer pump, 8 is an anode, and 9 is a power source.

As shown in FIG. 1, the multilayer printed circuit board 1 without through-hole plating has a plurality of conductor patterns 2 on the inner layer of the printed circuit board 1, and the connection of the conductor patterns 2 on the surface layer and between the layers is through holes passing through the conductor patterns 2. The inner walls of 3 are connected by forming through-pole plating 4 by electrodeposition of copper. However,
The circuit density that must be accommodated in recent printed circuit boards is high, the number of layers that make up the printed circuit board 1 is large, and the conductor pattern is narrow, so the perforation density of through-hole plating is high. The pore diameter A tends to be small and the pore length B tends to be large.

FIG. 2 shows a conventional plating method for a printed circuit board 1, in which the inner surface of the through hole 3 of the printed circuit board 1 to be through-hole plated is electrolessly plated, and then the plating solution 6 of the plating layer 5 is applied.
The electrolytic plating of copper is carried out by connecting the power source 9 and the plating solution 6. The plating solution 6 is refluxed by the cedar pump 7, and the through hole 3 is immersed facing the anode 8. Let it be distributed. Fortunately, if the perforation diameter A of the through hole 3 is small and the perforation length B is small, the flow resistance of the plating liquid 2 will be large, making it difficult for the plating liquid 6 to flow, and the plating liquid 6 will mainly be applied to the printed circuit board 1. The electrolytic copper in the center of the hole, where the plating solution is poorly metabolized, becomes inefficient, compared to the hole where the plating solution is metabolized relatively easily. The amount of plating was small, and the reliability of the connection of the conductive pattern 2 between each layer by the uneven through-hole plating 4 could not be obtained.

(4) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional art, the present invention provides a method for through-pole plating of printed circuit boards in which the diameter of the through-hole is small and the length of the hole is long, so that the amount of electrolytic copper deposited is uniform within the through-hole. The purpose of this invention is to provide a method for plating printed circuit boards.

(5) Structure and object of the invention According to the present invention, the plating tank is partitioned by a printed circuit board to be through-hole plated.
The suction port and the discharge port of the transfer pot are respectively connected, and the plating tank portion to which the discharge port is connected is closed using a partition wall of the printed circuit board to be plated through-holes, and the plating tank is pressurized by the transfer pump. This is achieved by allowing the plating solution to flow out into the plating tank connected to the suction port of the transfer pump through only the through-holes of the printed circuit board.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a diagram for explaining the method of plating a printed circuit board according to the present invention. In the figure, 51 is a pressure tank for the plating solution 6, 52 is a receiving tank for the plating solution 6, and 53 is a pressure tank for the plating solution 6. In the sealing mechanism, 71 is the suction port of the transfer bongua, and 72 is the discharge port of the transfer pump 7, respectively.

The plating tank 5 forms a sealed pressurized tank 51 with a sealing mechanism 53 and a partition wall made of a printed circuit board I in which through-holes 3 to be coated are formed, and is connected to the discharge lower 2 of the transfer pump 7, and a receiving tank 52 is connected to the plating tank 5. Connected to the suction lower 1 of the transfer pump 7.

The plating solution 6 is transferred to the pressurized tank 51 by the transfer pump 7 to form the plating solution 6 in a pressurized state, and is made to flow out into the receiving tank 52 only through the through hole 3 of the printed circuit board 1. The plating solution 6 constantly flows through the through hole 3 of the printed circuit board 1 without stagnation, and the plating solution is surely metabolized.

Furthermore, by providing the receiving tank 52 with a sealing mechanism similar to that of the tank 51, the direction in which the plating solution 6 is transferred by the transfer pump 7 is alternately reversed over time, and the plating solution flowing through the through hole 3 of the printed circuit board l is By reversing the flow direction of the liquid 6, more uniform electrodeposition of electrolytic copper can be obtained.

(7) Effects of the Invention As explained in detail above, the plating method for through-holes in printed circuit boards according to the present invention has a hole diameter of 0.4
mrr + ψ, hole length 5.5 mm, through-hole plating was performed, and the amount of electrodeposition at the plating liquid inlet of the through hole was 100.
Then, the value is 95 at the center of the hole length, and 90 at the outlet of the plating solution in the hole, and if the flow direction of the plating solution to the hole is reversed over time, each value is approximately 100.
becomes. On the other hand, in the conventional plating method, when the flow direction of the plating solution is reversed over time, when the amount of heavy coating at both ends of the through hole is 100, the weight at the center of the drilling length of the through hole is 30. ~40 electrodepositions, ↓) could not be done. In contrast, the present invention has an extremely uniform ``weighted value'' of the copper sheet! This is an effective through-pole plating method for through-hole plating, which has a hole diameter of 200 mm and a hole diameter of 200 mm and a longer drilling length. It is possible to ensure the reliability of the connection.

Furthermore, the plating solution distribution method of the present invention is also effective for processes other than plating, such as surface treatment inside through-holes.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a printed circuit board to which through-hole plating is to be performed, Fig. 2 is a side view for explaining a conventional through-pole plating method for printed circuit boards, and Fig. 3 is a printed circuit board according to an embodiment of the present invention. FIG. 3 is a side view for explaining a plating method. In the figure, 1 is a printed circuit board, 2 is a conductor pattern, 3 is a through-hole for through-hole plating, 4 is through-hole plating inside the through-hole, 5 is a plating tank, 52 is a receiving tank, 53 is a sealing mechanism, 6 is a plating solution, 7 is a transfer pump, 71 is a suction port,
Reference numeral 72 indicates a discharge port. Figure 1 Figure 8.2 Figure 3

Claims (2)

[Claims] (1) The plating tank is divided by a printed circuit board with through holes, one of the divided tanks is made into a sealed structure, and the plating solution is pumped into the tank with the sealed structure, and the plating solution is made to flow through the through holes. Characteristic printed circuit board plating method. (2) A patent characterized in that the divided plating tank is provided with a transfer pump having an inlet and a discharge port, and the transfer pump pumps the plating solution from the sealed tank to circulate the plating solution. A method for plating a printed circuit board according to claim 1.