CN-122002709-A - Laser ablation welding-resisting process

Abstract

The invention discloses a process method for laser ablation solder resist, and belongs to the technical field of PCB manufacture. The method comprises the steps of preprocessing a PCB substrate, silk-screen printing photosensitive solder resist ink, pre-baking, character spraying, post-baking to enable the ink to be completely crosslinked and solidified, and selectively removing the solder resist layer by laser beam ablation according to a preset pattern path. The invention does not need exposure and chemical development, does not involve developing solution, realizes dry-type and digital processing, is suitable for high-precision solder resist bridges, bonding pad windowing and the like, and obviously improves precision and environmental protection.

Inventors

• Xiong Yukang
• CHEN ZHONGJUN
• WANG GUO
• LI YANGUO

Assignees

• 泰和电路科技（惠州）有限公司

Dates

Publication Date

20260508

Application Date

20260311

Claims (9)

1. 1.A process for laser ablation solder resist, comprising the steps of: pre-processing the PCB substrate with the circuit manufactured; silk-screen printing photosensitive solder resist ink on the surface of the PCB substrate; pre-baking the PCB substrate subjected to silk printing; printing characters on the pre-baked PCB substrate in a spraying manner; post-baking the printed PCB substrate to completely crosslink and solidify the solder resist ink; and ablating the PCB substrate after post baking by using a laser beam according to a preset graphic data path, and selectively removing the solder mask layer in a preset area.
2. 2. The process of claim 1, wherein the pre-treatment step comprises physical or chemical cleaning of the PCB substrate to form a clean copper surface with a certain roughness.
3. 3. The process of claim 1, wherein in the screen printing step, solder resist ink is uniformly applied to the surface of the PCB substrate to cover the entire circuit area.
4. 4. The process of claim 1 wherein the temperature and time of the pre-bake step are set to partially volatilize the solvent in the solder mask ink to the extent that the ink dries to a set.
5. 5. The process of claim 1, wherein the character jet printing step is performed after the pre-bake step and before the post-bake step.
6. 6. The process of claim 1 wherein the post-bake step is at a temperature and for a time sufficient to fully crosslink and cure the solder mask ink to form the final solder mask layer.
7. 7. The process of claim 1, wherein in the laser ablation step, the laser beam is focused on the surface or inside of the solder mask layer, and the solder mask material is removed by photo-thermal or photochemical action.
8. 8. The process of claim 1 wherein the formation of the solder resist pattern does not include exposure and chemical development steps.
9. 9. The process according to any one of claims 1 to 8, wherein the process is used for making solder resist bridges, solder pad windowing or test point windowing on PCB boards.

Description

Laser ablation welding-resisting process Technical Field The invention relates to the technical field of Printed Circuit Board (PCB) manufacturing, in particular to a process method for processing a solder mask by adopting a laser ablation technology. Background In PCB manufacturing, a solder resist layer is used to protect the wiring, prevent solder shorting, and improve insulation reliability. The traditional solder resist process generally comprises the steps of pretreatment, silk screen printing, pre-baking, exposure, development, character, post-baking and the like. The exposure and development depend on photosensitive ink and chemical developer, so that the problems of edge side etching, solder resist bridge falling, development residues and the like exist, and the use of the chemical developer brings environmental protection pressure. With the development of electronic products to high density and high precision, the requirements of refinement, flexibility and green manufacturing are difficult to meet by the traditional process. Therefore, it is of great importance to develop a dry type solder resist processing method without mask and chemical development. Disclosure of Invention The invention aims to provide a process method for laser ablation resistance welding, which solves the problems of low precision, poor environmental protection and the like caused by chemical development in the prior art. In order to achieve the above purpose, the present invention provides the following technical solutions: a process method of laser ablation solder resist, comprising the following steps: pre-processing the PCB substrate with the circuit manufactured; silk-screen printing photosensitive solder resist ink on the surface of the PCB substrate; pre-baking the PCB substrate subjected to silk printing; printing characters on the pre-baked PCB substrate in a spraying manner; post-baking the printed PCB substrate to completely crosslink and solidify the solder resist ink; and ablating the PCB substrate after post baking by using a laser beam according to a preset graphic data path, and selectively removing the solder mask layer in a preset area. Further, the pre-treatment step includes physical or chemical cleaning of the PCB substrate to form a copper surface that is clean and has a certain roughness. The treatment can enhance the adhesive force between the solder resist ink and the copper surface, and avoid the ink falling off in the subsequent processing. Further, in the silk-screen step, the solder resist ink is uniformly coated on the surface of the PCB substrate to cover all the circuit areas. Ensure the circuit to be completely protected and prevent short circuit. Further, the temperature and time of the pre-baking step are set to enable the solvent in the solder resist ink to be partially volatilized, and the ink reaches the degree of drying and shaping. This step prevents the ink flow from causing pattern distortion during subsequent printing of the character. Further, the character jet printing step is performed after the pre-baking step and before the post-baking step. The sequence ensures that the character is not damaged by post baking, and the character layer is firmly combined with the solder mask layer. Further, the temperature and time of the post-baking step are set to fully crosslink and cure the solder resist ink to form the final solder resist layer. The hardness, heat resistance and insulating property of the solder mask layer can be improved by full curing. Further, in the laser ablation step, a laser beam is focused on the surface or inside of the solder mask layer, and the solder mask material is removed by photo-thermal or photochemical action. The laser processing is non-contact, high in precision and stress-free, window opening of any shape can be realized according to a preset pattern, developing solution is not needed, and the environment is protected and clean. Further, in the process, the formation of the solder resist pattern does not include exposure and chemical development steps. Therefore, the defects of edge side etching, bridge dropping and the like are thoroughly eliminated, the flow is simplified, and the treatment cost of chemical waste liquid is reduced. Further, the method is used for manufacturing solder resist bridges, solder pad windowing or test point windowing on a PCB. The method is particularly suitable for manufacturing the bridge resistance between the pads with fine pitches and the requirements of high-precision windowing. Compared with the prior art, the invention has the following beneficial effects: (1) The laser direct ablation is adopted to replace the traditional exposure development, and the mask-free and chemical wet process is adopted, so that the problems of side etching and bridge dropping are avoided, and the pattern precision is obviously improved. (2) The dry processing does not generate development waste liquid, has high environmental protection pe