Stephane, Whisker growth in tin and even some other metals (copper, aluminum and silver have been reported top grow whiskers) is a result of compressive stress. This stress can arise from high organics in the deposit, plating factors causing stress, contamination of the plating solution, and a deposit which is too thin. A rule of thumb is keep the organics as a %carbon less than 0.05% by weight, and plate a minimum of 200 microinches. Of course, if the tin is alloyed even with a small percentage of another metal like bismuth, the whisker effect should not appear. Good luck, Mike Carano -----Original Message----- From: Stephane Menard [SMTP:[log in to unmask]] Sent: Friday, September 03, 1999 9:30 AM To: [log in to unmask] Subject: [TN] Whiskers Problem on Leadframes Hi everybody !! I have a question regarding the well known problem of whiskers generation on leadframes. With the concept of lead free deposit and the investigation of several alternatives (Sn-Bi, Sn-Ag, Pure Tin, etc..) to Tin-Lead, we need to study the risk of generation of whiskers with those substitutes. It is generally agreed that Tin alloys (even at low percentage in the other metal) are not prone to this problem whereas pure Tin deposits are. However, does anybody have a recognized method (electrochemical, physical, etc...) which could help in predicting the apparition, or not, of this problem (besides the standard aging test which sometimes can be quite doubtful !) ? I am looking forward to your answers and comments. Sincerely, Stephane Menard Micropulse Plating Concepts [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 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 ##############################################################