A novel pin-pull tester and its application on PCB pad cratering assessment

The pin-pull test is appealing because it can obtain a very high percentage of laminate cracking failures. In this paper, a pin-pull tester using a promoted soldering method is designed and manufactured. The improved pin soldering process is provided based on a method proposed in previous study. First, the requirement to form solder ball on the printed circuit board (PCB) pad is canceled, and in addition the activation flux is utilized in the material preparation step instead of applying in soldering process. Second, A solder ball on the pin is required enough weight such that the liquid solder ball can drop down from a short distance during soldering step; herein, the enough weight is defined as that the gravity of liquid solder is bigger than the upward wetting force produced by the liquid solder to the heating pin. The software for the testing procedure has been developed for the tester too. Finally, the developed pin-pull tester is utilized to assess the strength susceptibility among three types of PCB pads. Following the promoted process, the pin can be soldered on the pad easily and effectively while the flux coating is activated. The manufactured pin-pull tester, assisting with the promoted testing procedure, can perform the testing successfully. The capability to perform the pin-pull testing automatically is the unique advantage of this developed tester. The test results indicate that large number of traces attached to the pad may significantly increase the pad´s strength such that resistance to the pad cratering is improved. The pin-pull tester is expected to be improved continuously, and used in many phases, such as pad designing, PCB material out quality control (OQC) & Incoming quality control (IQC) and quality control in product line.