Reliability of 80 mu m pitch flip chip attachment on flex

The interest toward flip chip technology has increased rapidly during last decade. Compared to the traditional packages and assembly technologies flip chip has several benefits, like less parasitics, the small package size an d the weight. These properties emphasize especially when hip chip component is mounted direct to the flexible printed board. In this paper flip chip c omponents with Kelvin four point probe and daisy chain test structure were bonded to the polyimide flex with two different types of anisotropically co nductive adhesive films and one anisotropically conductive adhesive paste. The reliability of small pitch flip chip on flex interconnections (pitch 80 mum) was tested in 85 degreesC/85% RH environmental test and -40 <----> +1 25 degreesC thermal shock test. According to the results it is possible to achieve reliable and stable ohmic contact, even in small pitch flip chip on flex applications. (C) 2001 Elsevier Science Ltd. All rights reserved.