Ok, here's one for discussion... We have a 68 ceramic leadless chip carrier that routinely yields insufficient solder at the corner locations. The details are: 10 mil stencil 1:1 apertures (stencil to board) Rounded apertures, rounded solder pads Sn63 solder paste (water soluble flux) Pretinned components (Sn63) Reflowed in air Observations are: Uniform pretinning solder volume Uniform HASL on boards Perfect solder deposits Perfect component placement Clean apertures after deposition Minute solder balls after reflow (nothing out of the ordinary) Here's the kicker... we use this same component on another board without the occurrences of insufficient solder. The difference is that on this design the solder pads and stencil apertures are rectangular, not rounded ends. I know that your first reaction is going to be "Well, it's obvious, rounded apertures deposit less solder paste than rectangular ones, thus the insufficient solder." I'd say "correct" except that the insufficient joints appear predominantly on the corners! BTW, the apertures are the same size throughout the component. Any ideas? Jim Marsico Senior Engineer Production Engineering AIL/Electronics Systems Group An EDO Company [log in to unmask] <mailto:[log in to unmask]> --------------------------------------------------------------------------------- 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 the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------