Method for directly drilling blind hole by laser using carbon dioxide

Abstract

The invention provides a method used for directly drilling blind holes by using CO2 laser; two or more different diaphragms are used to carry out direct laser boring, which is also called dual-diaphragm or multi-diaphragm mode; the method comprises the steps: 1) according to the diameter of the hole to be processed, a diaphragm is selected, the dimension of laser pulse dot is controlled, a pulse is used for ablating the copper layer on the surface of the processing plate so as to lead the copper layer to form an opening; 2) another diaphragm is selected, the dimension of the laser pulse dot is changed and less than that of the laser pulse dot in the step 1); one or more pulses are used to ablate the medium layer below the opened copper layer on the surface of the processing plate, thus forming a blind hole on the processing plate. The method can generate good laser hole shape, reduces copper slag at the circumference of hole, increases the taper of the hole, avoids the defects in electroplating process, is especially applicable to electroplating hole filling process after boring, and leads the electroplating liquid medicine easy to be replaced and the fovea to be reduced; furthermore, after electroplating, no hollow defects are generated, the preparation process is simple and the cost is low.

Description

technical field [0001] The invention relates to a method for directly drilling a blind hole by using a carbon dioxide laser. Specifically, different apertures are used to change the size of the laser pulse spot, ablate the copper layer and the dielectric layer respectively, reduce the hanging copper at the hole, and improve the shape of the blind hole. Background technique [0002] In the production process of high-density interconnected printed circuit boards and semiconductor packaging substrates, in order to realize the interconnection between layers, carbon dioxide laser drilling blind holes is often used, and the method of electroplating conductive layers is used to achieve. [0003] There are two methods of carbon dioxide laser drilling blind holes: opening copper windows and direct drilling. Since the untreated copper foil has a very low absorption rate of carbon dioxide laser energy with a fixed wavelength, the method of opening copper windows is required for laser ...

AI Technical Summary

Problems solved by technology

[0010] Micro-etching after direct laser drilling refers to micro-etching the copper layer of the printed board with chemical potion after drilling, which can etch away part of the hanging copper at the hole, but this method is costly, and the process is difficult to control, and it is easy to The copper layer at the bottom of the hole causes micro-etching and is not used much

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