I forgot to mention two additional important factors; 11) Solder joint/pad size 12) Cool down rate after exiting the wave John Maxwell At 09:06 AM 8/17/01 -0400, you wrote: >Last thought on this topic: > >Over the past 18 months, CALCE has seen a significant increase in ceramic >capacitor failures (thermal shock cracks, flex cracks, manufacturer flaws) >among its customers. In terms of pure speculation, its possible that the >huge demand for capacitors during the boom may have lead to some relaxation >in process control. > >What this implies is that your process was borderline to begin with, and >then the addition of caps with larger flaws or a lower fracture toughness >simply lead to the introduction of failures where there were none before. > >Best Regards >Craig > > >-----Original Message----- >From: TechNet [mailto:[log in to unmask]]On Behalf Of Bartkowaik Christine >Sent: Friday, August 17, 2001 6:56 AM >To: [log in to unmask] >Subject: Re: [TN] To wave or not to wave, that is the question... > > >Kevin: > >We have no problem with 1uf caps (TANT). Thus I suspect: >1- thermal shock >2- too long a time in the wave >2 s > >I would not suspect moisture if the boards have already been thru a reflow >oven and have not sat long. > >Chris > > -----Original Message----- > From: Kevin Stokes [SMTP:[log in to unmask]] > Sent: Thursday, August 16, 2001 4:26 PM > To: [log in to unmask] > Subject: [TN] To wave or not to wave, that is the question... > > Old problem: mounting ceramic capacitors to the bottom side of an >assembly and your customer wants you to wave them on. > > We are having problems with 0805 0.22 uF and 0.1 uF caps going >through wave and cracking during the process. We are following all of the >standard protocols (preheat, etc.). My understanding is that 0805s are >typically capable of handling this process. > > Anyone got any ideas short of moving the cap to the top or doing a >double sided reflow? > > Kevin > > Kevin Stokes > Reliability Manager > Kimball Electronics Group > (812) 634-4207 > > >---------------------------------------------------------------------------- >----- >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 >---------------------------------------------------------------------------- >----- > >--------------------------------------------------------------------------- >------ >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 >--------------------------------------------------------------------------- >------ --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------