Method for manufacturing depth-controlled metallized micropores in circuit board

Abstract

The invention relates to the technical field of printed circuit boards, in particular to a method for manufacturing depth-controlled metallized micropores in a circuit board. According to the invention, the back drilling processing is carried out after the electroless plating copper processing; the copper deposited on the first through hole in the copper deposition processing is very thin; the thickness of the copper layer is electroplated at one time to meet the design requirement of a final product; during back drilling, the hole diameter of the first through hole is relatively large; drilling slag can be guided out of the first through hole easily, the amount of the drilling slag, especially the amount of copper drilling slag, formed during back drilling can be reduced, meanwhile, the granularity of the copper drilling slag is small, large-particle copper drilling slag can be prevented from blocking the hole, the risk of hole blocking is reduced, and the reliability hidden danger inthe aspect of line conduction due to the fact that the copper drilling slag remains in the hole can be eliminated. According to the method, the processes of tinning and alkaline etching for removingthe copper drilling slag in the hole are reduced, the production process is shortened and simplified, the production efficiency is improved, and the production cost is reduced.

Description

technical field [0001] The invention relates to the technical field of printed circuit boards, in particular to a method for making depth-controlled metallized microholes on a circuit board. Background technique [0002] For multi-layer circuit boards, in order to transmit signals at high speed and meet impedance matching, etc., the mutual conduction between different layers is realized by making metallized holes. For some multi-layer circuit board products, it is necessary to set metallized holes with a small aperture and a certain depth on the board, that is, controlled depth metallized micro-holes. Due to the small aperture and large aspect ratio of the hole, it is difficult to make depth-controlled metallized micro-holes through the method of laser blind holes and electroplating filling holes. Generally, micro-back-drilled holes are produced by controlling the depth of the back-drilling process to achieve micro-metallized blind holes. function of the hole. Back drillin...

AI Technical Summary

Problems solved by technology

Using this method to make miniature back-drilled holes, especially for metallized through-holes with a diameter of less than 0.15 mm, the holes are likely to be unsmooth due to the formation of more and larger copper drilling slag during back-drilling. Drilling slag is led out from the hole to cause drilling slag to block the hole, and the drilling slag in the hole cannot be removed during alkaline etching, resulting in the etching potion and the potion in the subsequent wet process remaining in the hole, affecting the quality of the back-drilled hole, and even Lead to scrapping, and the copper drilling slag remaining in the hole will also affect the reliability of the line conduction