JPH05320927A - Device for masking printed board - Google Patents

Abstract

PURPOSE:To make the thickness of a plating film uniform by clamping the lower end of a printed board with a belt and moving a mask up and down in accordance with the height of the board to cover the upper end. CONSTITUTION:A printed board 4 is clamped by a belt conveyor 3, the contact part of the conveyor 3 with the board 4 is made of titanium and used as a cathode, and the riser part is also used as a lower mask. The upper part of the board 4 is masked with a mask 7 in a treating vessel 1, dipped in a plating soln. and covered with an anode 6 from both sides. The board 4 is moved in the treating vessel 1 by the conveyor 3 and plated. The mask 7 is moved up and down in accordance with the height of the board 4 to cover the upper end of the board 4, and hence the plating film thickness is made uniform.

Description

Detailed Description of the Invention

[0001]

[Industrial application] When performing plating treatment while carrying the bottom edge of a printed circuit board with a pair of belts,
The present invention relates to a masking device for a printed circuit board for averaging the plating film thickness.

[0002]

2. Description of the Related Art Conventionally, when a printed circuit board is plated, the peripheral edge of the printed circuit board is held by a large number of clips or engaging pieces on the inner periphery of a frame-shaped rack. There is a problem that the quality of the product deteriorates because a so-called dogbone phenomenon occurs in which the current concentrates on the part and the plating film thickness on that part increases abnormally.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to arrange a mask at an appropriate position according to the size of a printed board and average the plating film thickness.

[0004]

According to the present invention, there is provided a treatment tank having an anode, and a conductive substrate which is held in a vertical posture in the treatment tank while the lower end edge portion of the print substrate is connected to the negative electrode and which has a conductive contact via a belt. A belt conveyor with a pair of belts,
A masking device for a printed circuit board, comprising a vertically movable mask that covers an upper edge portion of the printed circuit board according to the height of the printed circuit board.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 in FIG. 1 is a processing tank (plating tank), a belt conveyor 3 consisting of a pair of belts 2 and 2a, and a low printed circuit board 4 whose lower end edges are sandwiched by both belts 2 and 2a. Group (lot) or a group of high printed circuit boards 4a pass through, a positive electrode 6 that covers the printed circuit board 4 in both sides of the processing tank 1 from both sides, and a printed circuit board 4 in the processing tank 1. And an upper mask 7 that can move up and down to cover the upper edge of the. A pipe (not shown) for replenishing the plating solution leaking from the slit 5 is connected to the processing tank 1, so that the prints 4 and 4a of any size are in a state of being immersed in the plating solution in the processing tank. Become. Reference numerals 9 and 9a denote driving drums that are driven in the arrow A direction and the opposite A direction, respectively.
Reference numeral 10 denotes a pair of racks whose lower ends are fixed to the upper surface of the mask 7 and is supported only for lifting and lowering. Pinions 11 mesh with both racks 10, and a shaft 12 integrated with the pinion 11 is supported only for rotation. Moreover, the front end is connected to the output shaft 14 of the drive motor 13 which can rotate in the forward and reverse directions. The mask 7 is provided with downwardly facing ribs 15 on both left and right edges of the lower end surface, and a groove 16 at the center thereof that faces (may be fitted into) the upper end edge of the printed circuit board 4, and is made of a corrosion-resistant resin. There is.

In FIG. 2 showing the internal cross section of the processing tank 1, the belts 2 and 2a are integrally provided with a backup titanium belt 16 on their inner peripheral surfaces (left and right side surfaces in FIG. 2), and the thickness of the lower half of the belts 2 and 2a is integrated. The outer peripheral surface of the pressure contact surface 17 is in pressure contact with the pressure contact surface 17, and the upper end of the pressure contact surface 17 is continuous with the substrate holding surface 19 via the step portion 18 that supports the lower end surface of the printed circuit board 4. At the substrate holding surface 19, the tip end surface of the titanium brush 20 is exposed at intervals in the longitudinal direction of the belts 2 and 2a (direction perpendicular to the paper surface of FIG. 2), and the base end portion of the titanium brush 20 is connected to the titanium belt 16. is doing. The belts 2 and 2a are slidably fitted in a fixed back plate 21 having a U-shaped cross section, and a corrugated plate 22 made of electrically conductive titanium, tantalum, or the like which is contracted between the back plate 21 and the titanium belt 16. Due to the elastic force, the titanium brush 20 and the substrate holding surface 19 are lightly pressed against the lower edge of the side surface of the printed circuit board 4. Reference numeral 23 denotes a plurality of negative electrodes, each of which penetrates the hole of the back plate 21 and is connected to the corrugated plate 22 so that the printed circuit board 4 can be energized from as many points as possible. Reference numeral 24 is a sponge-like elastic body that presses the corrugated plate 22 against the titanium belt 16.

FIG. 3 is a specific example of an overall sectional view including the portion shown in FIG. 2. Another flat plate-shaped lower mask 25 is fixed to the upper surface of the back plate 21 by a plurality of bolts 26. 27
Is a hole connected to a pressurized air supply source (not shown), and a large number of nozzles 28 extending upward from the hole 27 through the back plate 21 and the lower mask 25 are provided close to the printed circuit board 4. . Therefore, during the plating process, the nozzle 2
The pressurized air jetted upward from 8 vigorously agitates the plating solution in the vicinity of both side surfaces of the printed board 4, increasing the chances of contact of the plating solution with the printed board 4.

On the lower surface of the mask 7, a large number of guides 30 (protrusions) project from the ribs 15 on both sides toward the center part, and the upper edges of the printed circuit board 4 are held by the guides 30 on both sides. ing. The guide 30 acts so that the printed circuit board 4 maintains a vertical posture as much as possible.

When plating a lot of low printed circuit boards 4, the upper mask 7 is driven by the drive motor 13.
Is lowered to a preset height, and the upper edge of the printed circuit board 4 is covered with respect to the anode 6. As a result, it is possible to prevent an abnormal increase in the plating film thickness due to current concentration on the upper and lower edges of the printed circuit board 4. When the plating process of the low printed circuit board 4 is completed and the lot of the next high printed circuit board 4a is detected to approach the processing tank 1, the drive motor 13 rotates in the opposite direction and the mask 7 is suitable for the printed circuit board 4a. Raise to height and wait.

[0010]

According to the present invention, the printed circuit boards 4, 4a are
Since the lower edges of the belts are held by the belts 2 and 2a and are conveyed with reference to the lower position, the belt conveyor 3 also serves as the lower mask, and the upper mask 7 is automatically moved up and down by the controller according to the size of the printed circuit board. Since the upper edge of the printed board is covered, the plating film thickness can be averaged. The position of the upper mask 7 can be automatically determined by simulation.

[Brief description of drawings]

FIG. 1 is a perspective view of the device.

FIG. 2 is a partial sectional view taken along the line II-II of FIG.

FIG. 3 is a specific example of an overall cross-sectional view including the portion of FIG.

[Explanation of symbols]

 1 Processing Tank 2 Belt 2a Belt 3 Belt Conveyor 4 Printed Circuit Board 6 Anode 7 Mask 17 Pressure Contact Surface 18 Step 23 Negative Terminal 24 Elastic

Claims (1)

[Claims] 1. A pair of belts having a treatment tank having an anode and a vertically-arranged print substrate held in the treatment tank in a state where a lower end edge portion of the print substrate is connected to a negative electrode and having a conductive contact via a belt. A masking device for a printed circuit board, which comprises a belt conveyor provided with the above, and a mask which is movable up and down to cover the upper edge of the printed circuit board according to the height of the printed circuit board.