Drilling depth test method for multilayer circuit board

Abstract

The invention provides a multilayer circuit board drilling depth test method. The multilayer circuit board drilling depth test method includes the steps that parallel circuit modules and series circuit modules are manufactured on a plurality of conductive layers of a multilayer circuit board, and a plurality of pairs of testing bonding pads are formed on the conductive layers on the outer layer, wherein each pair of bonding pads respectively correspond to one of the conductive layers; via holes are respectively formed in the positions where the testing bonding pads are located, and the testing bonding pads are electrically connected with the parallel circuit modules of the conductive layers corresponding to the testing bonding pads and the series circuit modules of the conductive layers corresponding to the testing bonding pads respectively through the via holes; drill holes are formed the parallel circuit modules of the conductive layers on the outer layer and the series circuit modules of the conductive layers on the outer layer respectively; continuity of the testing bonding pads corresponding to a target conductive layer of the drill holes is detected, and the drilling depth is judged according to the detecting result of the continuity.

Description

technical field [0001] The invention relates to a circuit board testing technology, in particular to a method for testing the drilling depth of a multilayer circuit board. Background technique [0002] In the production process of multi-layer circuit boards, there are high requirements on the drilling process, including the control of the drilling depth of the finished board. Customers' precision requirements for drilling depth are generally limited by layers plus or minus a few mils (mil, a commonly used length unit in the circuit board industry, 1 mil = one-thousandth of an inch), that is, from the pressed multi-layer circuit Counting from the surface of the board, it is required to drill holes from the surface to the first layer of the board. When drilling, the depth to which the drill bit reaches the inside of the circuit board is precisely controlled by the parameters of the drilling machine, but due to the difference between the interlayer thickness of the circuit boa...

AI Technical Summary

Problems solved by technology

When drilling, the depth to which the drill bit reaches the inside of the circuit board is precisely controlled by the parameters of the drilling machine, but due to the difference between the interlayer thickness of the circuit board and the theoretical value during the pressing process, it is also subject to tolerances in the production process. The impact of the drilling depth parameters set according to the theory often cannot meet the customer's requirements

Usually the industry uses a depth gauge to test the drilling depth, but the accuracy of the depth gauge is low. Generally, it can only measure an approximate depth value, which cannot meet the technical requirements for high-precision drilling depth control.

Another test method is to slice and analyze the drilled part of the finished board and then use a microscope to measure the depth of the hole. This method is very accurate, but the efficiency is low, and the finished board will be destroyed, resulting in waste of cost.

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