Murata has not provided us with that bit of information. They will only tell us that we're not to exceed 275 degrees C for a maximum of 4 seconds. We've ran experiments at much higher temps and exposure times and have yet to destroy a component. That's why it's so hard for me to believe that our standard repair process is responsible for the failure... Leland -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Honsowetz, Eric Sent: Thursday, April 24, 2008 10:13 AM To: [log in to unmask] Subject: Re: [TN] Crystal Damage Question - Failure Mode Just wondering what temperature would the crystal withstand before it depolarized...? Perhaps Murata could provide this information. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Tuesday, April 22, 2008 1:50 PM To: [log in to unmask] Subject: Re: [TN] Crystal Damage Question - Failure Mode If the original rework was due to an electrical test failure such as would be seen if some other component failed, the crystal may have been electrically overstressed. In that case, the assembly may still contain the issue that caused this to happen. The rework may have been incidental, but possibly the voltage or current overstress is what caused the original component to fail, not necessarily the heat from the rework. You may wish to check the assembly to see if a wrong value cap or resistor was installed in the same (driver) circuit as the crystal location that was replaced and failed again. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall Sent: Tuesday, April 22, 2008 12:26 PM To: [log in to unmask] Subject: Re: [TN] Crystal Damage Question - Failure Mode Folks, I just went over the vendor's analysis report. In it, we were told that: "The crystal failed to oscillate in the initial check. The impedance-phase characteristics were checked, and we confirmed the impedance response was small due to the anti-resonant point being close to the resonant point. We confirmed that the piezoelectric characteristics became bad, and such were caused by depolarization. This can be caused by the application of excessive heat. Had this condition been present before shipment, our electrical characteristics sorting process would have been rejected this component, so we think the failure was caused after shipping from Murata." That's all the info I have. Thanks again for your help. Leland -----Original Message----- From: Stadem, Richard D. [mailto:[log in to unmask]] Sent: Tuesday, April 22, 2008 12:26 PM To: TechNet E-Mail Forum; Leland Woodall Subject: RE: [TN] Crystal Damage Question Was the crystal open, exhibiting wrong frequency, shorted, or what? Was there any test analysis/troubleshooting data? We need that in order to hazard a guess as to how the rework may have affected the part or suggest a failure analysis strategy. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall Sent: Tuesday, April 22, 2008 10:16 AM To: [log in to unmask] Subject: [TN] Crystal Damage Question Technetters, We recently had a Murata SMD crystal to cause a failure in the field. This particular unit had been to Repair and the component was manually replaced during the manufacturing process. The vendor analysis reported the component saw excessive heat during the rework and caused internal depolarization which led to failure. We made 10 attempts to re-create this condition and were unsuccessful in doing so. We used dual soldering irons, had the temps cranked as far as they would go, and gave them excessive exposure times. Could the vendor analysis have been incorrect, or was their explanation a real possibility? Why were we not able to replicate this? 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