What was the duration and ramp times on your 1812 capacitor tests? ---------- From: TechNet-request To: TechNet Subject: Re: ASSY:FAB:Des: Joint Cracking LCCCC Date: Friday, September 13, 1996 11:45AM Bob, I have seen serious cracking in tests on 1812 capacitors in -55 to +125C test. They are a good bit smaller and the TCE mismatch not so bad so I am not at all surprised at what you are seeing. I would treat 1206's as the limit in kit that is going to see those sorts of temperatures (-55) regularly in service, unless measures are taken to reduce the problem. David Whalley >I have been looking at some 20 pin Leadless Ceramic Chip Carriers which have >exhibited cracks. They are mounted on standard FR4 and thermal cycled between >-55 +80 for 1000 hours. > >Cracking is a problem with this device as we know but not at these low lead >counts. Many uses in their design rules make 28 pin devices the limit and then >incorporate the use of matched substrate to reduce differential expansion. > >I would appreciate any feed back on failure that people have seen on testing of >low lead count devices or even feed back on where people see the limit on pin >count and the need for special substrates. *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************