Method for improving PCB (Printed Circuit Board) solder resist via hole blockage

Abstract

The invention discloses a method for improving PCB (Printed Circuit Board) solder resist via hole blocking. The method comprises the following steps: pre-processing; carrying out white screen silk-screen printing; pre-baking is performed; performing alignment exposure for the first time through a preset film; developing for the first time; performing alignment exposure for the second time through a preset film; developing for the second time. According to the method, an exposure and development process is added after PCB solder mask exposure and development, so that the solder mask layer needing to be reserved is fully photo-cured, and residual ink in the hole is flushed under the condition that solder mask edge lateral erosion is not affected when development is carried out again, so that the purpose that the via hole is not blocked is achieved.

Description

technical field [0001] The invention relates to the technical field of PCB production, in particular to a method for improving the plugging of PCB solder resist via holes. Background technique [0002] At present, there are many batches, models, and types of PCB manufacturers on the market. The solder mask is made by white screen screen printing. White screen screen printing is easy to cause the small hole ink to enter the hole and block the hole. After the film is exposed to the position, the remaining solder mask ink is bright After curing, the non-retained solder mask is blocked by film and is not exposed to light, and then the non-photosensitive ink is washed away by developing weak alkali. With the development of PCB and the improvement of corresponding quality, the function of via holes not only stays in conduction, but some via holes also carry functions such as functional testing and heat dissipation, which requires that these holes cannot be soldered and blocked . ...

AI Technical Summary

Problems solved by technology

[0004] 1. For boards with copper thickness ≥ 2OZ or via holes < 0.35mm, due to the high pressure of silk screen printing, more oil enters the via holes, and the normal development and flushing is done once, but the flushing is not clean;

[0005] 2. Prolonging the development time can rinse the ink in the via hole, but it is easy to appear that the solder mask covered area and the non-covered area are connected and the amount of side erosion of the solder mask layer increases (excessive development), resulting in the solder mask bridge falling off and PAD after surface treatment Functional defects such as edge resistance soldering and oil loss

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