Here are some things that I would look for: 1. Good solder paste "Brick" on both pads of 805, if one is less in volume. After reflow if component is missing then there should be solder bumps were pads are. 2. Is one side of 805 connected to large thermal mass area, meaning temperature on one side of compnent is liquifying faster than other, causing the Tombstone. 3. I have seen some component especially resistors, loose or have their end metalization missing, this will not allow the component end to solder. 4. Just check Reflow Profile, if #2 is suspected, place thermocouples at those points to measure the acutal temperatures. 5. Span or footprint of 805 may be issue, if 805 is just making connection, when Solder joint relows, then surface tension will pull component to one pad or other. Hope this may help if I think of some more I will send it your way Tom B. -----Original Message----- From: Becerra Alejandro [SMTP:[log in to unmask]] Sent: Wednesday, May 10, 2000 11:09 AM To: [log in to unmask] Subject: Re: [TN] Tombstoning and missing parts on 0805 Resistors The problem is after reflow soldering -----Original Message----- From: Tom Braswell [mailto:[log in to unmask]] Sent: Wednesday, May 10, 2000 3:15 PM To: 'TechNet E-Mail Forum.'; Becerra Alejandro Subject: RE: [TN] Tombstoning and missing parts on 0805 Resistors Are components present or skewed prior to Reflow Soldering, Just after palcement. -----Original Message----- From: Becerra Alejandro [SMTP:[log in to unmask]] Sent: Wednesday, May 10, 2000 10:27 AM To: [log in to unmask] Subject: [TN] Tombstoning and missing parts on 0805 Resistors Hi Technetters, We are having some problems with tombstoning and missing parts on 0805 resistors. We think that the problem is related to the component, since we only detect the problem in some specific codes of the material. Could you please tell me what can I look in the components? Thanks in advance Alejandro Becerra MSC Phone (915)841-8518, Fax (915)841-8401 [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 ############################################################## ############################################################## 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 ##############################################################