Tenison, If you have checkout pad geometry, stencil aperture geometry, and your placement process, the problem may reside in the reflow process. Have you taken a thermal profile of the process? If so, look to see that you have proper preheating of the assembly. If that all looks good, check the solderability of the components. Try both sides of the components. It is unlikely that this will be the problem, but it couldn't hurt to check it out. What you are looking for is anything that might cause an uneven wetting force on one side of the component. This isn't a complete list, but it should get you started in the right direction. If you want to talk about this, feel free to give me a call. Hope this helps John Guy ACI / EMPF 714 N. Senate Ave. Indianapolis, IN 46202-3112 voice: (317) 655-EMPF ext.130 fax: (317) 655-3699 e-mail: [log in to unmask] -----Original Message----- From: Tenison Stone [SMTP:[log in to unmask]] Sent: Monday, November 24, 1997 2:41 PM To: [log in to unmask] Subject: [TN] tombstoning I have having trouble with tombstoning on a large flat with lots of 0402 parts. I have investigated pad geometry, stencil aperture geometry, and recalibrated placement equipment. Can anyone help with this problem? Tenison Stone Telex Communications ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ############################################################## ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################