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FA dude
Guest	Posted: Mon Jun 20, 2026 11:35 am    Post subject: Failed @ -5C, Intermittent @ 25C, Passed @ 75C   Dear fellow engineers, Have you ever come across a unit, tested @ time 0 (no stress test or anything), Failed @ -5C, Intermittent @ 25C, Passed @ 75C? ATE datalog showed disastrous result, most of the tests show zero voltages and currents, when device failing at -5C. X-Ray showed normal wire-dressing, lead fingers, and die-pad. CSAM showed no delam. Anything you can share is deeply appreciated
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Polgi-Wan
Joined: 08 Jun 2026 Posts: 18 Location: CV	Posted: Mon Jun 20, 2026 2:32 pm    Post subject:   hi FA dude, which test (or tests) are failing on bench/ATE? how many rejects/good parts do you have? have you looked into golden/standard/reference units? kind regards.
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FARel Engr
Joined: 20 Jun 2026 Posts: 76	Posted: Mon Jun 20, 2026 5:46 pm    Post subject:   Quote: Failed @ -5C, Intermittent @ 25C, Passed @ 75C I'm almost pretty sure that what you have is an intermittent wirebond problem, i.e., any of the following: lifted first or second bond, neck break, or heel break. You will not see these in Xray or CSAM because the fractured surfaces are still touching each other (held in place by the molding compound), except at low temp. Decap the part with intermittent bonds and do a visual inspection on the wire. Note that the issue can either be at the first or second bond. Are you seeing a delam in the affected pin? If yes, then the delam probably caused the lifting or breaking.
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Guest
	Posted: Wed Jun 22, 2026 10:04 am    Post subject:   Hi FArel Engr, how can you be so sure that it is a wirebond problem without looking into the failure mode? Some devices failed because the failure mechanism are temperature sensitive. Could be fab-related defects or sometimes are non-visual.
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FA dude
Guest	Posted: Wed Jun 22, 2026 5:01 pm    Post subject: Failed @ -5C, Intermittent @ 25C, Passed @ 75C   Polgi-Wan wrote: hi FA dude, which test (or tests) are failing on bench/ATE? how many rejects/good parts do you have? have you looked into golden/standard/reference units? kind regards. I'm glad you asked. The device is a hard-drive controller. The failures at ATE/bench are zero servo, write, and read voltages and currents (at -5C). It's like no activity at all. But the register bits are alive. Device is working normal at 75C. Golden units work normal at all temps.
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FA dude
Guest	Posted: Wed Jun 22, 2026 5:05 pm    Post subject: Failed @ -5C, Intermittent @ 25C, Passed @ 75C   FARel Engr wrote: Quote: Failed @ -5C, Intermittent @ 25C, Passed @ 75C I'm almost pretty sure that what you have is an intermittent wirebond problem, i.e., any of the following: lifted first or second bond, neck break, or heel break. You will not see these in Xray or CSAM because the fractured surfaces are still touching each other (held in place by the molding compound), except at low temp. Decap the part with intermittent bonds and do a visual inspection on the wire. Note that the issue can either be at the first or second bond. Are you seeing a delam in the affected pin? If yes, then the delam probably caused the lifting or breaking. Thanks for the advice, FARel Engr. That's exactly what I thought in the first place, but this unit had no delam. X-Ray was also clean. OK, I'll try to decap and see. It could be fab-related, temp-dependent problem also. We'll see...
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El-Kid-de-Sparc
Joined: 23 Jun 2026 Posts: 7 Location: Espana	Posted: Thu Jun 23, 2026 10:07 am    Post subject:   hmm. . . . could be a design issue (temp-sensitive) especially if this is a new product. if this is a legacy (old) product, go ahead with FA. . . . good luck!
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FARel Engr
Joined: 20 Jun 2026 Posts: 76	Posted: Thu Jun 23, 2026 3:38 pm    Post subject:   Quote: Hi FArel Engr, how can you be so sure that it is a wirebond problem without looking into the failure mode? Hi, I believe FA Dude described his failure as catastrophic: Quote: ATE datalog showed disastrous result, most of the tests show zero voltages and currents, when device failing at -5C. FA Dude, do you have a curve tracer? It is important that you curve trace first at -5C and 25C to see that the affected pins are really open before you decap. If you are seeing breakdown voltages at -5C, then your problem is not intermittent bonds. If you're seeing open pins at 5C, then I'm really almost sure that you have intermittent bonds.
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Guest
	Posted: Mon Jul 04, 2026 1:33 pm    Post subject:   I believe you can't have zero output on both voltage and current on a single output! if it is 0V the pin could be open, if 0A it could be short. I hope FA dude could share the outcome of his analysis.
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FARel Engr
Joined: 20 Jun 2026 Posts: 76	Posted: Mon Jul 04, 2026 6:24 pm    Post subject:   Hi Guest, I think it's the other way around: if the pin is open, then you'll get 0 A for all values of voltage applied to the pin; if the pin is shorted; then you'll get 0 V for all values of current (there will be huge currents too). In this FA, FA Dude needs to confirm if the pin is open, so he'll check if the curve tracer will display a purely horizontal line passing through 0 A at -5 deg C. This would indicate that at -5 deg C, the fractured bond or wire separates, resulting in an open pin. FARel Engr
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