[sdiy] Odp: Tantalum manufacturing / assembly failures OT?
modular at go2.pl
Thu Nov 15 07:15:51 CET 2018
I've only used couple of thousands SMD tantalums ever, so this may not be so reasonable quantity to say anything, but I remember only once it failed from unknown reason, at first power up. There were aslo few other incidents in products working for some time, but it was always because connecting power in reverse. I switched to ceramics as replacement some time ago, but with current price/shortage situation I may welcome tantalums back soon. Roman Dnia 14 listopada 2018 18:51 Richie Burnett < rburnett at richieburnett.co.uk > napisał(a): Since we're discussing Tantalum capacitors, has anyone else who manufactures things in reasonable quantities, (either hobby, SDIY or in their day job,) had problems with SMD Tantalum capacitors failing short or partially shorted due to excessing heat during reflow? I've had a bunch of boards made by a well known UK PCB fab and population company, and several off them had 100uF/25V Panasonic SMD Tantalums fail short-circuit within about 10 seconds of powering up the board. Just to rule out a design issue, the two capacitors that were failing only saw 15VDC from a well regulated power supply, and charge slowly through a resistor so there is no significant inrush current or AC ripple current either. And they weren't installed with incorrect polarity! The two devices that failed on each board are right next to a D2PAK SMD power device that is clearly discoloured from excessive temperature during assembly, so I can only suspect that the use of a hot-air pencil during assembly is the culprit! I haven't used SMD tants that extensively in electronics, so would be interested to hear others experiences, either on list or via PM. -Richie, ______________________________ Synth-diy mailing list Synth-diy at synth-diy.org synth-diy.org synth-diy.org
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