Coupon for detecting depth and alignment precision of back drilling hole

Abstract

The invention provides a coupon for detecting the depth and the alignment precision of a back drilling hole. The coupon used for detecting the depth and alignment precision of a back drilling hole comprises a back drilling face, a layer needing to be drilled, a layer incapable of being drilled, a layer adjacent to the layer incapable of being drilled and a non-back drilling face, the layer needing to be drilled is located below the back drilling face, the layer incapable of being drilled is located below the layer needing to be drilled, the layer adjacent to the layer incapable of being drilled is located below the layer incapable of being drilled, the non-back drilling face is located below the adjacent layer of the layer incapable of being drilled, the layer needing to be drilled, the layer incapable of being drilled and the layer adjacent to the layer incapable of being drilled are sequentially distributed between the back drilling face and the non-back drilling face from top to bottom, and the back drilling face is matched with the non-back drilling face. The coupon for detecting the depth and the alignment precision of the back drilling hole has the advantages that the alignment precision level is measured more accurately, the alignment precision is tested synchronously, and the utilization rate of jointed boards is reduced.

Description

technical field [0001] The invention relates to the technical field of back-drilling detection, in particular to a coupon for detecting the depth and alignment accuracy of back-drilling holes. Background technique [0002] With the development of 5G high-speed products, the requirements for signal transmission quality are getting higher and higher. In order to reduce signal bypass and interference, back drilling is often used to control the stub of the via. More and more, in order to obtain the alignment accuracy and depth accuracy of back drilling more accurately, an auxiliary test coupon is often made on the edge of the graphics. Generally speaking, back drilling refers to further processing of PCB boards that have completed multi-layer lamination. Through the process of "mechanical drilling through holes - controlled depth drilling - glue removal - copper sinking - electroplating - tin plating - back drilling - back drilling detection", the impact of the accuracy of the P...

AI Technical Summary

Problems solved by technology

[0003] However, in the prior art, when the step hole is processed, the drilling accuracy is affected. The alignment of the drilling machine in the industry is calculated according to Six Sigma (+ / -3σ), and the hole position accuracy is + / -0.075mm. Therefore, the general depth control Holes and back drilled holes are 0.075-0.125mm larger than through holes on one side. Although the diameter of back drilled holes is larger than that of through holes, it can completely ensure that the copper in small holes is removed, but when it is as large as the controlled deep hole, there are some defects as follows , when the back drill is offset relative to the controlled deep hole, follow the conventional back drill stub control, the customer requires the stub length to be less than 0.254mm, and the general board edge test attachment strip controls the stub at a median value of 0.127mm, according to the conventional control, when the board There is no deviation between side back drilling and controlled depth drilling. When there is a deviation in a certain part of the graph, there may be reliability risks such as solder ring open circuit. In order to avoid the risk of stepped back drilling, more precise depth control is required. The knife can cover the influence of the deviation of the drilling hole position. The main factors affected are the extremely poor plate thickness. After testing the section of the coupon, confirm that the stub is greater than the extremely poor plate thickness to ensure that there will be no risk of open circuit. However, for stepped back drilling, except The plate thickness is extremely poor, and there is a risk of partial open circuit caused by hole deviation

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