Authors: Asif R. Chowdhury, Jin Seong Kim, Young Duck Yoon Date Published: 1/17/2006
Pan Pacific Symposium
Abstract: Camera module production has increased dramatically in the recent years due to wide scale adoption of cameras in mobile phones. It is expected that over 250 million camera modules will be shipped in mobile phones in 2005. Driven by small size and flexibility requirements, most of these camera modules are attached to flexible circuits. Camera modules for mobile phones predominantly use plastic lens elements as part of its optics. The use of plastic lenses in camera modules poses challenge for the flex circuit attach process. Plastic lens can not withstand the high reflow temperatures of standard SMT process commonly used for flex attach. Hot-bar is an alternate method that is used for flex attach to camera modules. However, hot-bar process can also adversely affect camera module optical performance. Evaluations were done to find the best hot-bar process parameters and process flow with respect to the modules optical performance and the solder joint integrity between the camera module and the flex circuit. This paper describes these evaluations, the results and provides a solution for optimal hot-bar process. It also provides examples and brief evaluation summary of three other methods for camera module flex circuit attach.