A lot of these consumer products are getting good at meeting the intent of the mil/hi reliabilty requirements without a lot of the added expense. Most of the engineers I work with have never seen a mil spec, but they know that when a guy drops his GPS, it bounces off the boat and goes in the water. When the guy fishes it out he expects it to work again. Best Regards; Tom G. --- On Wed, 6/8/11, Andy Kowalewski <[log in to unmask]> wrote: > From: Andy Kowalewski <[log in to unmask]> > Subject: Re: [DC] Underfill for chip scale packages > To: [log in to unmask] > Date: Wednesday, June 8, 2011, 8:57 PM > Makes sense. So it (corner bonding) > would be applied to packages that are a > bit bulky (=heavier than normal) and maybe don't have so > many pins to absorb > drop shock? > > Thanks Steve. > > Cheers........ > > Andy Kowalewski > AdvantagePCB Pty Ltd > +61 (2) 9499 4853 > > -----Original Message----- > From: DesignerCouncil [mailto:[log in to unmask]] > On Behalf Of Steve > Gregory > Sent: Thursday, 9 June 2011 09:06 > To: [log in to unmask] > Subject: Re: [DC] Underfill for chip scale packages > > Hi Andy, > > Corner bonding, not underfill. It helps with surviving drop > shock without > having to go through all the trouble of underfilling. > Corner bonding is lots > > easier to do... > > Steve > > -----Original Message----- > From: Andy Kowalewski > Sent: Wednesday, June 08, 2011 6:53 PM > To: [log in to unmask] > Subject: [DC] Underfill for chip scale packages > > Just saw a web knock-down of the Barnes and Noble eBook > reader. The larger > Chip Scale Packages appear to have underfill applied to > each corner, which > has me intrigued. See > > > > http://www.techrepublic.com/photos/cracking-open-the-2011-barnes-noble-nook- > e-book-reader-wi-fi/6243892?seq=35 > <http://www.techrepublic.com/photos/cracking-open-the-2011-barnes-noble-nook > -e-book-reader-wi-fi/6243892?seq=35&tag=content;thumbnail-view-selector> > &tag=content;thumbnail-view-selector > > > > Does anyone know the criteria for this? Underfill is > applied in flipchip > assembly to prevent the silicon cracking because of the > thermal mismatch in > CTE between glass (3ppm/degree C) and pcb (FR4 at about > 16ppm/degreeC). I > guess the CSP might have a similar issue - no doubt the > silicon chip inside > the package also gets stressed as the package stresses, > which implies that > there isn't a lead frame to give compliance, or a FR4 > laminate interposer > like in bga packages that doesn't need stress relief. > > > > Cheers........ > > > > Andy Kowalewski > > AdvantagePCB Pty Ltd > > +61 (2) 9499 4853 > > > > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email > Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > ---------------------------------------------------------------------------- > ----- > DesignerCouncil Mail List provided as a free service by IPC > using LISTSERV > 16.0. > To unsubscribe, send a message to [log in to unmask] > with following text in > the BODY (NOT the subject field): SIGNOFF DesignerCouncil. > To temporarily stop/(restart) delivery of DesignerCouncil > send: SET > DesignerCouncil NOMAIL/(MAIL) > For additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ---------------------------------------------------------------------------- > ----- > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email > Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > > ______________________________________________________________________ > > ---------------------------------------------------------------------------- > ----- > DesignerCouncil Mail List provided as a free service by IPC > using LISTSERV > 16.0. > To unsubscribe, send a message to [log in to unmask] > with following text in > the BODY (NOT the subject field): SIGNOFF DesignerCouncil. > To temporarily stop/(restart) delivery of DesignerCouncil > send: SET > DesignerCouncil NOMAIL/(MAIL) > For additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ---------------------------------------------------------------------------- > ----- > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email > Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > > ______________________________________________________________________ > > --------------------------------------------------------------------------------- > DesignerCouncil Mail List provided as a free service by IPC > using LISTSERV 16.0. > To unsubscribe, send a message to [log in to unmask] > with following text in > the BODY (NOT the subject field): SIGNOFF DesignerCouncil. > To temporarily stop/(restart) delivery of DesignerCouncil > send: SET DesignerCouncil NOMAIL/(MAIL) > For additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > --------------------------------------------------------------------------------- > ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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