Method for testing PCB pad bonding strength

Abstract

A disclosed method for testing PCB pad bonding strength comprises the following steps: 1) presetting a solder ball at one end of a test pull pin, and arranging a first soldering-flux wrapping layer on the surface of the solder ball; 2) arranging a second soldering-flux wrapping layer on a PCB sample pad; 3) enabling the test pull pin and the target PCB sample pad to be in vertical centering relationship; 4) enabling the first soldering-flux wrapping layer on the preset solder ball and the second soldering-flux wrapping layer on the pad to be contacted with each other; 5) fusing the preset solder ball on the test pull pin with the target PCB sample pad, so as to form a new welding point; 6) finishing welding between the test pull pin and the target PCB pad; 7) vertically pulling the test pull pin upwards, recording the maximum peeling force and drafting a pull curve; and 8) repeating the steps 1)-7), so as to obtain the pad cratering failure mode, the maximum peeling force and the pull curve of multiple target PCB sample pads and realize evaluation on the PCB pad bonding strength. The method possesses the advantages of concise steps and high operationality, and is relatively beneficial for realizing full-automatic on-line quality detection.

Description

technical field [0001] The invention relates to a quality detection technology of a printed circuit board, in particular to a method for testing the bonding strength of a PCB pad. Background technique [0002] The use of halogen-free substrates and lead-free solders for printed circuit boards (PCBs) is an inevitable direction for the development of microelectronics manufacturing. In the process of PCB manufacturing and use, multiple reflow soldering and rework processes will cause the interface layer between the PCB pad and the substrate fiber to withstand multiple thermal stresses. In addition, in order to adapt to the lead-free process, the PCB design has also been improved accordingly. These changes not only make the printed circuit board more brittle and more prone to breakage, but also cause the interface layer at the bottom of the PCB pad to withstand higher thermal stress, which is prone to the common phenomenon of PCB pad cratering. As stated in the academic paper ...

AI Technical Summary

Problems solved by technology

Aiming at the cost problems of existing methods in terms of consumables, equipment, and fixtures, the publication number is CN104181103A "A Pull-out Test Method and Device for Evaluating Bonding Strength of PCB Pads" which discloses a new pad strength testing method However, on the one hand, some steps of the method require manual intervention in the test, and the test process cannot be automatically controlled; on the other hand, before the test, the PCB sample of the method needs to undergo a reflow soldering process, so that the pad Subjected to a thermal shock, affecting the estimation of the actual pad quality

Images