hi, in our particular case, the pwbs are 10 layer/48 mils thick and 8 layer/39 mils thick; the smallest via is 13 mils. we have experienced no via failures with copper in the vias. some people would add nickel plating if they thought there were going to be z-axis expansion problems. phil -----Original Message----- From: Louis, Edwin @ CSE [mailto:[log in to unmask]] Sent: Tuesday, March 07, 2000 11:28 AM To: [log in to unmask] Subject: Re: [TN] Alloy 42 Leaded TSOPS Do you know how to over come the enhanced Z-axis CTE and the problem of cracked vias? -----Original Message----- From: Phil Crepeau [mailto:[log in to unmask]] Sent: Friday, February 18, 2000 4:41 PM To: [log in to unmask] Subject: Re: [TN] Alloy 42 Leaded TSOPS hi, i think that thermount (random kevlar fiber) reinforced epoxy or polyimide laminate would be a reasonable choice. there's no weight penalty to pay. does your design have other parts that are plastic packaged? if so, what would you do about them? phil -----Original Message----- From: Louis, Edwin @ CSE [mailto:[log in to unmask]] Sent: Friday, February 18, 2000 11:11 AM To: [log in to unmask] Subject: [TN] Alloy 42 Leaded TSOPS We have a sole source for TSOP components, in which, they are only available with alloy 42 leads. The vendor refuses to build the parts with Copper leads because the CTE of alloy 42 better matches the die CTE and as result they have fewer component failures and defects. Does any one know of a PWB material that would better match the CTE of alloy 42 leaded TSOPs? ############################################################## 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 ############################################################## ############################################################## 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 ############################################################## ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ############################################################## ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################