X-ray inspection study with PCB cavity press-fit connectors

Abstract

X-ray inspection on connectors becomes more and more important in these years as more connectors are mounted on PCBA due to their apparent benefits1-2. In this paper, we would like to share our studying experience for PCB Cavity Press-Fit connector on cavity PCB area. Our assembly with two press-fit connectors are inspected with the AXI, in order to make sure there is no broken pins enclosed inside the cavity, especially at the connector pins area. We have been working with AXI3, AXI5 and AXI6, and looking for good solutions for the last year. AXI3 is normal AXI (Automated X-ray Inspection); AXI5 and AXI6 are special AXI machines which have CT (Computed tomography) capabilities. Both AXI5 and AXI6 have capabilities to detect broken pin in cavity connector pins area with very clear X-ray images, and pass/fail judgments are independent of their operator skills. However AXI5 and AXI6 testing times are longer than AXI3. Finally we has developed good method to solve its issue at AXI after more than one year studying: the Algorithm and Threshold setting of AXI3 will be discussed in the paper. Recently AXI3 has capabilities to detect defect with PCB Cavity Press-Fit connector with very good balance between defects escaped percent and false call PPM. With joined studies and collaboration between Flextronics AXI team and AXI 3 R&D for eight months, outcome of the collaboration is very promising. Defects escaped rate has reduced from 20% to 0%, while false call PPM has reduced from >10,000 PPM to <500 PPM.