Resuming answers to several questions: At this time development engineers are reconsidering pcb-case-terminal-solder CTEs interaction. Laboratory eng reported test cycling temperature didnt pass in no case +125°C Both pictures are from the same specimen under test. Due too solder connection displacement when "cracking" in one of them you cann´t see the golden surface of terminal just at the left side. Degolding was done from double pre-tinned Thermal cycling is: 100 cycles -50°C to +125°C . Ramp rate per each cycle is 45´ (-50 to +125°C) (I´m sorry for correction, engineer test laboratory at first time reported +50°C to +125°C) brgds,Ricardo >>> George Wenger <[log in to unmask]> 19/04/2016 10:02 >>> It also won't hurt to do an XRF measurement on the PCB surface finish to know how thick the ImmAu and EPd were on the PCB ----- Original Message ----- From: "David Hillman" <[log in to unmask]> To: [log in to unmask] Sent: Tuesday, April 19, 2016 8:31:22 AM Subject: Re: [TN] Solder Cracking After Thermal Cicling Hi Richard - Ricardo had mentioned the component leads were "double tinned" to remove the gold but it sure wouldn't hurt to do a simple cross section to confirm that gold embrittlement wasn't playing a role in the issue too. Dave On Tue, Apr 19, 2016 at 7:03 AM, Stadem, Richard D. < [log in to unmask]> wrote: > I agree with Dave, but with the addition that Steve may be on to something > in that the "before" picture shows some gold, the "after" picture does not, > so this may not be the same terminal. But that is irrelevant; what I am > adding here is that the gold may be contributing to the issue as well, in > the form of embrittlement. > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman > Sent: Monday, April 18, 2016 7:25 PM > To: [log in to unmask] > Subject: Re: [TN] Solder Cracking After Thermal Cicling > > Hi folks - this case isn't as complicated as it might look. Its a simple > case of CTE mismatch. The component lead is very very short with no strain > relief bend. And as Joyce mentioned, the lead base metal may be > accelerating the solder shear forces (i.e kovar or alloy 42). Add in the > influences of the board laminate, the component body construction and the > solder joint volume/pad size, you end up with the result shown in the > photos. > > Dave Hillman > Rockwell Collins > [log in to unmask] > > On Mon, Apr 18, 2016 at 5:05 PM, Ricardo Moncaglieri < > [log in to unmask]> wrote: > > > Jim, > > Temp cycle range is +50°C to +125°C. > > I dont have yet the temp ramp rate. > > brgds,Ricardo > > > > >>> "Maguire, James F" <[log in to unmask]> 18/04/2016 19:02 > > >>> > > What is temp cycle condition again? You have 50 to 125C but did you > > mean -50C to +125C? Also are you doing temp cycle or air/air temp > > shock (ie. what is ramp rate in chamber or better yet as measured on > > the product during temp cycle). > > > > > > Jim Maguire > > Intel Corporation > > ATD Q&R Stress Lab Operations > > Hawthorne Farms; Oregon > > Engineer > > Phone: 503-696-3309 > > Cell: 253-651-9373 > > > > -----Original Message----- > > From: TechNet [mailto:[log in to unmask]] On Behalf Of Ricardo > > Moncaglieri > > Sent: Monday, April 18, 2016 2:58 PM > > To: [log in to unmask] > > Subject: Re: [TN] Solder Cracking After Thermal Cicling > > > > Steve, > > Responding your question. > > > > Soldered connection is not put under vibration during temp cicling. > > > > This terminal belongs to a connector which is screwed on a case and > > its terminal passes through this metalic case and lyies on the pcb > > ENEPIG pad. > > So that there are following CTEs playing and intercating each other > > all > > together: > > > > PCB CTE > > Solder CTE > > Case CTE where is screwed the conector Terminal CTE > > > > brgds,Ricardo > > > > >>> Steve Gregory <[log in to unmask]> 18/04/2016 18:47 >>> > > Hi Ricardo, > > > > I finally have your pictures up, they are here: > > > > > > http://stevezeva.homestead.com/A15_Photos_of_pre__post_100_temp_cyclin > > g_CSC-10_SN12.pdf > > > > Boy, that looks like a big CTE mis-match. A question; are the boards > > going through ESS? Vibration along with the temp cycling? > > > > Steve > > > > On Mon, Apr 18, 2016 at 2:35 PM, Ricardo Moncaglieri < > > [log in to unmask]> wrote: > > > > > Steve, > > > Attached arethe pictures. > > > Thank you a lot. > > > Await for your comments. > > > brgds,Ricardo > > > > > > >>> Steve Gregory <[log in to unmask]> 18/04/2016 15:22 >>> > > > Hi Ricardo, > > > > > > The Technet server strips the attachments, send your photo directly > > to me > > > and I'll get it posted... > > > > > > Steve > > > > > > On Mon, Apr 18, 2016 at 11:43 AM, Ricardo Moncaglieri < > > > [log in to unmask]> wrote: > > > > > > > Dear colleagues; > > > > > > > > Steve Gregory, could you please upload the enclosed picture? > > > > > > > > Solder become perturbated / cracked after thermal cicling: > > > > > > > > This picture corresponds to a plane (not circular) conector > > terminal > > > > solded to a pcb pad ENEPIG finished. > > > > The connector terminal has been gold removed by twice pretin. > > > > Solder used is Sn63Pb37. > > > > Thermal cicling: 50°C to 125°C > > > > > > > > As picture showed there are stretch marks toward left direction > > and > > > > showed solder crack. > > > > > > > > Our provider reported temperature didnt pass over 125°C and solder > > used > > > > 63/37. > > > > > > > > Question: > > > > > > > > How could these kind of gooves or stretch marks have been produced > > > > > > taking into account they are just toward one direction (left) and > > of > > > > considerable length? > > > > Just mecanic stress? > > > > Temperature overpassing on any cicle? > > > > Need of use of different alloy, ie.: In, Bi etc? > > > > Provider reported the process is being useed from them since long > > ago > > > > (same solder alloy, temperature, pcb, terminal conector, thermal > > > > cicling) but this is the first time they faced with such a > > cracking. > > > > > > > > Do you have any comment in order to anlyse/solve this trouble. > > > > > > > > Appreciate your feedback we are in middle of a providing > > acceptance > > > > tests space quality level (IPC class 3). > > > > > > > > brgds,Ricardo > > > > > > > > > > > > > > > > > > ______________________________________________________________________ > > > > This email has been scanned by the Symantec Email Security.cloud > > service. > > > > For more information please contact helpdesk at x2960 or > > > [log in to unmask] > > > > > > ______________________________________________________________________ > > > > > > > > > > -- > > > > > > > > > This email and any attachments are only for use by the intended > > > recipient(s) and may contain legally privileged, confidential, > > proprietary > > > or otherwise private information. 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