Hi Dan, can you give the exact dimensions of the round land pattern? Thanks, Ioan > -----Original Message----- > From: Dan R. Johnson [SMTP:[log in to unmask]] > Sent: Wednesday, April 10, 2002 10:22 AM > To: [log in to unmask] > Subject: Re: [TN] 0402 tombstone problem > > Steve, > I use round pads to decrease pad size (increase circuit density). A side > benefit seems to be less chance of skew, I don't have numbers on > tombstoning/drawbridging, but product hasn't yelled. I have also been > tinkering with the idea of other geometries just haven't come across the > right application yet. > Dan > > ----- Original Message ----- > From: [log in to unmask] <mailto:[log in to unmask]> > To: [log in to unmask] <mailto:[log in to unmask]> > Sent: Tuesday, April 09, 2002 8:12 PM > Subject: Re: [TN] 0402 tombstone problem > > I just heard something not too long ago, that round pads for 0402's > are the way to go. > > Never heard of that before, but just recently received a board for > quote that uses round pads for the 0402 components...anybody else ever > heard of this? > > Guess I'll find out how it works inna little while, while pondering > why a round pad would work better than a square pad.... > > -Steve Gregory- > > > > > Edward, > > When we do everything correct on 0402 and 0201 and still > have components > standing-up, we often look to the component terminations and > find poor > plating. > > Good luck > Dave Fish > > ----- Original Message ----- > From: "Edward S. Wheeler" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Tuesday, April 09, 2002 10:59 AM > Subject: [TN] 0402 tombstone problem > > > > Hi folks, we are running a new board with 0402 parts on > it. It seems that > > we are having a tombstone problem as well as a problem > with parts not > > staying centered on the pads. We are currently using 20 > mil square pads on > > the board, with 20 mils of spacing between them. Our > stencil is 6 mils > > thick, laser cut and electro polished. The trapezoidal > walled apertures > are > > slightly reduced, 17 mils square, and centered on the > pads. It appears the > > chip shooter is placing the parts perfectly. We are using > eutectic solder > > paste with an OA flux, and reflowing the parts using the > recommended > profile. > > > > Are there any suggestions any of you might have concerning > this size of a > > part? Is there a better stencil design, reflow profile, or > pad design that > > could help us out? I would appreciate any suggestions. > > > > Thanks. > > > > Ed > > > > --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------