Oups, Ian ; by the sound of it you're in a jam ; don't get crossed if I see in my crystal ball (one) something what does not agree with your hard facts : 1) Somewhere; I think in one of Werner's papers I've read anything less than 6mm of ceramic on FR4 stands the dilatation's . That should not be it ; I presume the "problem" is plain crack ; even without reliability cycling . 2) Circular cutter ( CAB in V ?) ; or more so still the handling is more likely ( as you've guessed as well = 0.6 mm end of pad from blade is highly inconsiderate to the senior cap in question ; I have to say ; you design fellow likely does not know the blade diagonal stresses in travel ; levered by the size of that thing is sure recipe for crack . You have my sympathy > hey ; keeps us in job ! 3) The remedy would likely be : a] Abandon the circular blade ; it will stress the "design" even if your operator will feed the panel through on feathers . Or change the design = move the cap in ; the corner is A brutal place . b] If (likely) you can not do anything about design ; than shear ( yes, a very good guillotine ) will help . AND feather support ; obviously ; terrified gentle gender is much more suitable than "confident" handy man . May I suggest subsequent use of the French Instrument consequently utilizing design lad's voluntary cooperation . c] break the biscuits PRIOR assembly . See you Ian Paul Klasek colleague on the other side http://www.resmed.com > ---------- > From: Ian Squires[SMTP:[log in to unmask]] > Sent: Wednesday, 4 November 1998 5:34 > To: [log in to unmask] > Subject: [TN] 2220 ceramic cap failure > > All > Well here it is! my monthly poser for the forum. > This is one that has come back to haunt me a little, in my first few > weeks with my current employer i was asked to look at a Small gating > circuit with a production 'eye'. > I was unhappy about several of the design features and said so.....but > being 'johnny come lately' was largely ignored. > So....we have a board 28mm x 9mm x 0.9mm, populated both sides with > 0805's, 0603's, SOT23's and a ceramic cap 2220. > guess what the problem is??? yep the LARGE cap > > Cte mismatch between the ceramic and the FR4 in my opinion is too > much.....agree/disagree? > The component has one pad running parallel with the long side of the > PCB 2mm inboard. The other pad runs parallel with the other long side > of the PCB....0.6mm inboard. > The boards (50 to a panel) are populated, reflowed both sides and then > cut out using a circular cutter. > Pad distance from edge and likely vibration damage are surely > wrong...agree/disagree??? > Any other possible problems or areas of note would also be appreciated > as design are still refusing to accept any of this (assuming i am on > the right track), hard evidence or IPC related docs would be > appreciated. > Meanwhile we have a line stoppage and our subcontractor is being > blamed for poor manufacture. Anyone want to fight their corner with > me??? > > > Regards > Ian Squires > Senior Production Engineer > ------------------------------------------------------- > > Graseby Dynamics Ltd > A Smiths Industries Company > Park Avenue, Bushey, Watford, Herts, WD2 2BW > Web Site: www.gradyn.co.uk > Phone: 01923-228566 xt 295 > Fax: 01923-221361 > E-mail: [log in to unmask] > > Registered in England no. 480992 > Registered office: > 765 Finchley Road, London, NW11 8DS > ------------------------------------------------------- > > ################################################################ > TechNet 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 TechNet <your full name> > To unsubscribe: SIGNOFF TechNet > ################################################################ > 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 > ################################################################ > ################################################################ TechNet 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 TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ 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 ################################################################