Tom, Another thing to check is finish metallization of the leads. Is it Alloy 42 or palladium? If so, that could contribute to wetting issues. Thanks, Robert Furrow SMT Process Engineer Lucent Technologies 978-960-3224 [log in to unmask] <mailto:[log in to unmask]> -----Original Message----- From: Jeffery L. Hempton [SMTP:[log in to unmask]] Sent: Tuesday, July 18, 2000 11:56 AM To: [log in to unmask] Subject: Re: [TN] (TN) Reflow Issue Tom, I agree with Ioan, check to see if pins are not bent "up" and are able to touch the paste before reflow. Almost every instance I have had with "pillowing", i.e. leads sit on top of solder and solder has good reflow, but forms under the lead (looks like, you know, a pillow!) has been due to old/oxidized leads that are not wetting. Some tests I ran in the past demonstrated that solder pastes with 2% silver actually increased the wetting properties of these oxidized leads, but that is a longer term fix (requalification of paste). We use paste with 2% silver partly for this reason. I would perform some solderability tests, then push this problem back to your device supplier if they are within shelf life. good luck, Jeff Hempton United Technologies Electronic Controls ______________________________ Forward Header __________________________________ Subject: Re: (TN) Reflow Issue Author: "Tempea; Ioan" <SMTP:[log in to unmask]> at CARMAIL Date: 07/18/2000 12:31 PM Tom, the first thing to check is the date code on the components. Most likely they are old and the leads are oxidized, hence the dewetting you describe. What to do with the bad components, this is the question. I dont think you should try tinning them, since with their fine pitch you'll end up with tons of shorts. If you are using more sorts of solder paste, try one with a stronger flux for these assemblies. Or maybe the leads are not oxidized, but only not coplanar, so some of them don't even touch the paste, so they will not form a joint. Good luck, Ioan > -----Original Message----- > From: Thomas Han [SMTP:[log in to unmask]] > Sent: Tuesday, July 18, 2000 12:17 PM > To: [log in to unmask] > Subject: [TN] Reflow Issue > > Hi all, > > I have been noticing on our last batch of boards that we ran, some of the > tsop flash chips were not reflowing properly. I am not getting very good > toe fillets on the chips and some appear as though they are just sitting > on > top of the reflowed solder. This board has a good component mix(i.e. BGA, > QFPs, PLCCsocket, SOICs, total(325-350)). Other components reflow fine, > but for some reason these TSOPS are not. Is there something that we are > overlooking? > > Your input would be greatly appreciated. Thanks in advance > > Tom > > ############################################################## > 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 ############################################################## ############################################################## 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 ##############################################################