Frank, Could you elaborate a little more on item 2: orientation of components? What kind of forces would be causing damage? Thanks, Peter > -----Original Message----- > From: Kimmey, Frank [SMTP:[log in to unmask]] > Sent: Tuesday, September 22, 1998 10:54 AM > To: [log in to unmask] > Subject: Re: [DC] SMD Capacitors Cracking > > Hi John, > We too had the 1206 cap problem. > Ours was a .33uF, 50V, Z5U > We found many attributes causing failure. > List is not in order of occurrence: > > 1. position of cap on PCB (close to edge) > PCB flex from depanelization caused micro-cracks (some showing at > test, mostly field failures) > 2. orientation of components (we found stress when parallel to > direction > of flow) > 3. Vendor compatability (we found some vendors parts to be borderline) > 4. Profile (temperature ramp-up and cool-down can significantly > effect) > > Also you may want to research John Maxwell's articles on cap failures. > Please feel free to call me and we can discuss further. > Hope this helped! > FNK > > > Frank N Kimmey C.I.D. > EM Designer > C&K Systems, Inc > 916-353-5366 > [log in to unmask] > > ---------- > > From: John Olivier[SMTP:[log in to unmask]] > > Reply To: DesignerCouncil E-Mail Forum.;John Olivier > > Sent: Tuesday, September 22, 1998 7:40 AM > > To: [log in to unmask] > > Subject: [DC] SMD Capacitors Cracking > > > > I was very interested to see that there are a number of people who > > have > > the same problem as we are experiencing regarding SMD capacitors. > > > > We have found a number of our 100 NF 50 Volt ceramic de-coupling > > capacitors are going short circuit after 9 months or more. The > > capacitors are not a dead short, but are pulling down the VCC line. > > > > We are using Kemet X7R 1206 caps. The caps are connected VCC to > > Ground. > > Once the cap or caps have been replaced the units work. > > > > The printed circuit board is FR4 and is 1.6 mm x 15 cm x 6 cm. The > > boards go through 2 soldering stages ie. one for the SMD components > > and > > then for the conventional components. > > > > The printed circuit board once completed is coated with a urethane > > MS472N conformal coating. > > > > I would appreciate any information or suggestions you could offer. > > > > > > Thanks Very Much > > > > John Olivier > > > > Quality Assurance Manager > > > > ################################################################ > > DesignerCouncil E-Mail Forum 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 DesignerCouncil <your full name> > > To unsubscribe: SIGNOFF DesignerCouncil > > ################################################################ > > Please visit IPC's web site (http://www.ipc.org) "On-Line Services" > > section for additional information. > > For technical support contact Hugo Scaramuzza at [log in to unmask] or > > 847-509-9700 ext.312 > > ################################################################ > > > > ################################################################ > DesignerCouncil E-Mail Forum 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 DesignerCouncil <your full name> > To unsubscribe: SIGNOFF DesignerCouncil > ################################################################ > Please visit IPC's web site (http://www.ipc.org) "On-Line Services" > section for additional information. > For technical support contact Hugo Scaramuzza at [log in to unmask] or > 847-509-9700 ext.312 > ################################################################