The CTE of: Upilex S = 8 ppm/C Kapton HN = 18 ppm/C Kapton KN = 17 ppm/C Apical AV = 21 ppm/C Apical NP = 8 ppm/C at temperatures less than 100C The flex circuit material is typically a composite of polyimide film, adhesive, and copper in varying ratios. The CTE of Copper is 17 ppm/C, but the adhesive can exhibit a variety of CTEs depending on the formulation and temperature. To estimate a CTE for your particular composite flex structure you can use the flex analysis software I developed for Rogers some years back available at: http://www.geocities.com/CapeCanaveral/Launchpad/9641/program/program.html or at http://www.rogers-corp.com/cmu/software.htm Andy Magee - Flex Guru Senior Consultant, Bourton Group [log in to unmask] (937) 435-3629 Brett wrote, Does anyone know the CTE (coefficient of thermal expansion) of Upilex-S and Kapton flex circuit material? I have data sheets from Rogers, but they don't list CTE values. Thanks for the help! Brett Goldstein EVI, Inc. ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################