Printed circuit board processing technology

Abstract

The invention provides a printed circuit board processing technology. The printed circuit board processing technology includes the steps: step 1, making via holes on a to-be-processed multi-layer board, namely drilling the via holes and making copper layers I on the inner walls of the via holes requiring back drilling; step 2, drilling backdrill holes on the multi-layer board obtained at the step 1; and step three, making copper layers II on the basis of the copper layers I on the inner walls of the via holes subjected to back drilling at the step 2. Making the copper layers on the inner walls of the via holes requiring back drilling includes a pre-backdrilling stage and a post-backdrilling stage, so that the thickness of the copper layers on the inner walls of the via holes is smaller than the final thickness required by the technology due to the procedure arrangement, metal chips generated during back drill are effectively reduced in terms of the amount and size as compared with those in the prior art, and the backdrill holes are less prone to blockage. The copper layers on the inner walls of the via holes subjected to back drilling are thickened to the thickness required by the technology, so that the requirements of the technology are met.

Description

technical field [0001] The invention relates to a printed circuit board processing technology, in particular to a printed circuit board processing technology requiring back drilling. Background technique [0002] In the manufacturing process of the PCB board, through holes are needed to realize the electrical connection between the layers of the inner circuit board. The through holes are usually drilled by a drilling machine, and the processing accuracy requirements are high. A conductive layer is formed in the via to achieve electrical connection. However, the ends of some plated through holes are not connected, which will cause the signal to fold back, and the resonance will also be reduced, which will cause reflection, scattering, delay, etc. of signal transmission, which will bring "distortion" to the signal. This requires further processing of the plated through holes, ie back drilling. The function of back drilling is to drill out the through-hole section that does n...

AI Technical Summary

Problems solved by technology

[0004] At present, communication continues to develop, and communication 3G, 4G, and 5G have appeared one after another. High-frequency communication backplanes require smaller and smaller hole spacing to meet the high capacity per unit area, and the accompanying back-drilling hole diameter continues to decrease. The corresponding technical difficulty of small hole back drilling is that the back drilling is blocked but difficult to break through

[0005] The back-drilling blockage refers to that in the process of back-drilling, due to the debris under the back-drilling, especially copper shavings, tin shavings, and resin shavings in shapes such as massive and filamentous shapes, the via holes are blocked, and the chemical solution during etching It cannot be exchanged, the back drill hole becomes a blind hole, and the liquid medicine is easy to remain in it, which brings great hidden dangers to the follow-up process and product quality.

[0006] For example: the copper of the back-drilled hole is generally more than 25 μm, plus a tin protective layer of about 5 μm, the metal thickness is more than 30 μm, for holes of 0.25 mm and smaller, it is very easy to cause via hole blockage

[0007] Therefore, in order to solve the above technical problems, most of the existing processes adopt secondary drilling and other schemes to dredge the blocked via holes. Such processing technology is very complicated and cumbersome.

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