Back drilling depth control method

Abstract

The invention relates to the technical field of PCBs, and discloses a back drilling depth control method. The method comprises the following steps: providing a multilayer board, wherein the multilayer board comprises a first metalized through hole with a first conductive layer on the hole wall, a second metalized through hole with a second conductive layer on the hole wall, and a third conductive layer; controlling a drilling tool to perform back drilling at the position of the first metalized through hole, wherein the composite drilling tool comprises an insulated outer insulation part located on the outer surface of the cutting front end and a conductive outer conductive part located on the outer surface of the cutting rear end, the outer conductive part is electrically connected with the middle electric connection unit, and the outer conductive part, the third conductive layer, the second conductive layer, the middle electric connection unit and the outer conductive part are sequentially connected to form a switch control loop; and in the back drilling process, when the switch control loop is switched from the open circuit state to the short circuit state, controlling back drilling to be stopped. According to the embodiment of the invention, by controlling the stop of the back drilling when the state of the switch control loop is identified to be converted, the depth of the back drilling can be accurately controlled, and the control precision of the drilling depth is effectively improved.

Description

technical field [0001] The invention relates to the technical field of PCB (Printed Circuit Board, printed circuit board), in particular to a back drilling depth control method. Background technique [0002] With the development of wireless network communication technology, the signal transmission rate is getting higher and higher. PCB is an important part of signal transmission, and the Stub (excess hole copper) length of the signal hole is one of the key indicators. [0003] The stub is like an extra "tail" in the transmission line, which acts as a notch filter; when there are two such stubs in the signal transmission line, an oscillation section will be formed. Whether it is filtering or oscillation, it will damage the transmission of high-speed signals and distort the signal. Therefore, it is very important to improve the back-drilling accuracy and shorten the length of the stub. [0004] At present, the following two methods are usually used for back drilling: [000...

AI Technical Summary

Problems solved by technology

However, the above two back-drilling methods both use the same command to control the back-drilling depth to produce back-drilled holes with the same preset theoretical drilling depth, without considering the aforementioned plate thickness difference phenomenon, resulting in stubs in each back-drilled hole. There is a large deviation

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