I believe the apparent contradiction results from IPC-SM-840 being a _Soldermask_ Performance and Qualification Spec. not a board/assembly spec-- it doesn't apply directly to PWBs or PWAs. Just because you put on a mask that meets IPC-SM-840 doesn't mean your board will meet IPC-6012, or the assembly will meet IPC-A-610, etc. You also have to have proper surface prep, cure, etc. Tim Reeves ECD > ---------- > From: Tom Burek > Sent: Tuesday, May 23, 2000 12:55 > Subject: Help! Interpret IPC-SM-840C and IPC-A-61 > > Hello, > Can one of you experts out there or perhaps someone from IPC interprets > what appears to be a contradiction. > IPC-SM-840C 3.5.2 Adhesion states that per table 2 a high reliability > Rigid PCB that has a surface finish of Gold or Nickel can have a maximum > 5% loss allowed on solder mask over a coupon per TM 2.4.28.1 of IPC-TM-650 > (Tape test). > IPC-A-610 , 7.2 Coatings states a Non-conforming Defect- Class 1,2,3 > Degradation of the mask film that permits solder bridging or exposed basis > metal. > > Can someone kindly differentiate the meanings? > > Thank You, > Tom Burek > Product Engineer > [log in to unmask] > ############################################################## 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 ##############################################################