Method for eliminating solder mask ink in via hole of printed circuit board

Abstract

The invention discloses a method for eliminating solder mask ink in a via hole of a printed circuit board, which comprises the steps of S1, cleaning a substrate and a conductive copper layer on the surface of the substrate, roughening the surface of the conductive copper layer through a polishing device, and cleaning the substrate and the conductive copper layer again; S2, carrying out silk-screenprinting, specifically, printing an ink layer with a preset color on the conductive copper layer; S3, conducting pre-baking, specifically, pre-baking the silk-screen printed circuit board; S4, performing primary exposure, specifically, performing alignment exposure by using a film, performing photocuring on the solder mask ink, and shielding the via hole and the periphery by using a shading partof the film; S5, developing for the first time, and removing the ink at the position shielded by the shading part of the film; S6, drying the circuit board. S7, performing secondary exposure, specifically, performing secondary alignment exposure by using a film, and performing secondary photocuring on the ink layer; S8, developing for the second time, and removing the residual solder resist ink inthe via hole; and S9, drying the circuit board. The solder mask ink in the via hole can be effectively eliminated, the integrity of an ink layer is ensured, and assembly welding bridge partition is prevented.

Description

technical field [0001] The invention belongs to the field of circuit board production, in particular to a method for eliminating solder resist ink in a through hole of a printed circuit board. Background technique [0002] In the production process of printed circuit boards, the ink will block the small-diameter via holes when printing with solder resist ink, and when the customer requires that there should be no residual ink in the via holes, the existing method is to print the screen on the screen. A baffle or a plug is set on the position corresponding to the via hole, but the production of the printing screen in this way is difficult and costly, and the position accuracy of the plug behind the baffle is not easy to control, and it is impossible to completely and effectively avoid the solder resist ink. Into the via hole, and this method can only be used for single-sided printing, and when making a double-sided circuit board, it is necessary to print on both sides separat...

AI Technical Summary

Problems solved by technology

[0002] In the production process of printed circuit boards, the ink will block the small-diameter via holes when printing with solder resist ink, and when the customer requires that there should be no residual ink in the via holes, the existing method is to print the screen on the screen. A baffle or a plug is set on the position corresponding to the via hole, but the production of the printing screen in this way is difficult and costly, and the position accuracy of the plug behind the baffle is not easy to control, and it is impossible to completely and effectively avoid the solder resist ink. Into the via hole, and this method can only be printed on one side, and when making a double-sided circuit board, it is necessary to print on both sides separately, and the production efficiency is low

Another method is to perform back development on the defective products with solder resist ink entering the via holes, and this method will lead to excessive development during the second development, showing such Figure 7 The state shown leads to the lack of ink at the edge of the via hole, and even the occurrence of undesirable phenomena such as the isolation of solder bridges between ICs, resulting in rework or scrapping of the circuit board

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