Blind hole uncapping method using laser

Abstract

The invention relates to a blind hole uncapping method using laser. The blind hole uncapping method comprises the steps that grooving laser beams are irradiated to a surface layer conducting layer ofa to-be-uncapped circuit board substrate, laser etching is carried out on the surface layer conducting layer of the to-be-uncapped circuit board substrate according to a preset track, and an annular groove is formed; and heating laser beams are irradiated to the annular groove and a to-be-uncapped surface layer conducting layer area on the inner side of the annular groove, heating is carried out,the surface layer conducting layer of the circuit board substrate on the inner side of the annular groove becomes loose and drops off by heating, the blind hole uncapping is finished, and a primary blind hole is formed. According to the blind hole uncapping method using the laser, the surface layer conducting layer of a circuit board is subjected to closed-loop grooving using the grooving laser beams, the annular groove is obtained, the annular groove and a conducting area in the annular groove are heated using the heating laser beams, under the action of plasma shock waves generated by actionof heating laser light spots and substance in the groove, the surface layer conducting layer of a blind hole to-be-uncapped protecting area becomes loose and drops off, the blind hole uncapping is finished, the primary blind hole is formed, and the blind hole uncapping problem is ingeniously solved.

Description

technical field [0001] The invention relates to the technical field of laser processing, in particular to a method for uncapping a laser blind hole. Background technique [0002] At present, carbon dioxide laser circuit board drilling occupies an absolute position in the field of blind hole drilling of hard boards and rigid-flex boards. Because carbon dioxide lasers do not absorb copper foil well, many of them use copper on the surface of the circuit board to open windows to expose the underlying layers. The insulating layer of the glass fiber cloth layer and the adhesive layer allows the carbon dioxide laser to directly act on the insulating layer until the lower layer is exposed to complete the blind hole drilling function. [0003] In this process, the action of removing the upper layer of copper is called blind hole uncapping. The basic requirement for blind hole uncapping is to reliably remove the surface copper skin, and it is required not to damage or evenly remove a ...

AI Technical Summary

Problems solved by technology

[0003] In this process, the action of removing the upper layer of copper is called blind hole uncapping. The basic requirement for blind hole uncapping is to reliably remove the surface copper skin, and it is required not to damage or evenly remove a part of the lower insulating layer, which is beneficial to the subsequent carbon dioxide laser. Evenly remove the corresponding insulating layer. If the corresponding insulating layer is removed unevenly during the blind hole opening process, then the blind hole processed by carbon dioxide is likely to be uneven, and there will be damage to the bottom copper or residual glue on the bottom copper. These are all poorly processed blind holes. , is absolutely not allowed

The existing blind hole capping generally adopts the method of scanning the spiral line after focusing the ultraviolet laser to remove the surface copper skin to complete the blind hole capping. Uniform removal affects the stability of subsequent carbon dioxide laser processing of blind holes

[0004] Why does the use of ultraviolet laser helical scanning of copper skin have the hidden danger of uneven removal of the interlayer insulation layer? Because only the copper skin is removed and the intermediate insulating layer is damaged as little as possible, it is necessary to control the UV laser in a suitable laser power state. If the surface of the circuit board is uneven, it is necessary to increase the UV laser processing power to a certain extent. In some area, the laser material removal ability is high, and excess ultraviolet rays will cut into the intermediate insulating layer, resulting in different thicknesses of the insulating layer in each blind hole area to be processed, leaving hidden dangers for the stability of subsequent carbon dioxide laser drilling

[0005] The traditional laser blind hole uncapping uses a laser beam to spirally clear the conductive layer on the surface of the blind hole to be opened, which has low efficiency, poor thickness uniformity of the insulating layer at the bottom of the blind hole, and easy delamination of the blind hole wall when heated. shortcoming

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