Effect of Different Flex Materials to the Reliability of High Density FCOF (Flip Chip on Flex) Interconnection

摘要

The results from the evaluation of two different types of flexible substrates (polyimide and epoxy glass) for high-density flip chip application are presented in this paper. Cross section samples were made to analyze the possible failure mechanism of failed contacts. Two different test devices were used (contact areas 50x50μm and 50x90μm). The effective pitch was 80 μm in both samples and the number of contact was around 200. The matrix of the anisotropically conductive adhesive that was used was epoxy based and the conductive particles were isolated soft metal-coated polymer particles. The contact resistance was measured with four-point method and the series resistance with Daisy chain method. The reliability of the flip chip interconnections was tested in thermal cycling and humidity tests.