A Study on Repetitive Drop Test Method and for Electronic Component

In recent years, mobile phones have been miniaturized, so electronic components with high I/O count have been changed from QFP/SOIC to BGA/LGA. However BGA/LGA tends to have weak reliability for drop impact, and the drop reliability needs to be improved. For that, board level drop reliability has an important role in order to evaluate drop reliability for electronic components excluding influence from phone mechanics. This study focuses on the characterization of the test methods using experimental test, strain analysis and FEM simulation. In this paper, board level drop test shows drop a fixture with a component assembled on PWB. The drop test using a fixture with a flat bottom lacked of repeatability of failed drop count, and it was improved by adding hemisphere at the center on fixture bottom to reduce the influence by variation of falling posture angle, and strain analysis and the drop experimental proved it, too. The deformations of the fixture influence the test results, because the deformation of fixture caused high stress on solder joints. For that, the method to exclude the influence of fixture deformation was studied, and it was found that the influence can be decreased by supporting condition of PWB with a free-sliding end or the new design of the fixture. On the other hand, the effect of height of drop, mass of fixture, and supporting condition on the drop test, can be thought as the acceleration factors for the dropping load conditions. The drop tests were done in many load conditions. The results were analyzed by strain analysis and FEM simulation. As a result, an accelerating ratio can be evaluated by predicting the effect of these factors, and effective dropping test can be conduct without increasing the dropping height exceedingly.