How to find out exposed copper windings with missing wire coating in DCP021212DU?

DCP additional high (HV) isolation resistance meter (2000Mohm/1KV and 200Mohm/500V) test will only degrade the internal wire. Each test must be limited to 1 sec and degraded by at least 20% .The primary reason for wire degradation can occur if the DCP is exposed to a high humidity environment followed by high temperature exposure, such as solder re-flow temperatures. Any additional  HV voltage tests after reflow process for greater than 1 sec can force the unit  to degrade the wire.  

1. Once the MSL 3 package is open, it must be used within defined shelf life of 168 hours. . Prior to the next reflow processing, any remaining -unused converters must be dry packed and pre-baked (typically for 16 hours at 125°C when removed from the reel) for maximum reliability prior to the next reflow process. . The package must then   resealed with sufficient desiccant bags to maintain the MSL-3 level control at all times and prior to the next reflow process. any storage temperature30°C and or  humidity >60%  when not stored in compliance with MSL-3 requirements  requires new prebake per Jst 033C. Your units will require a prebake of at least 23 -30days at 40°C(humidity ≤5% in the T/R pack prior to reflow.
2. The additional additional high (HV) isolation resistance meter (2000Mohm/1KV and 200Mohm/500V) test has likely  degraded the  wire with the h possibility of new failures after reflow installation.
3. Tom

JiaHuag:

All DCP series components are 100% tested for leakage prior to exiting the factory. The High-pot 1kV for 1 second  leakage test  insures  the transformer  isolation barrier between  secondary to primary windings. This test confirms  primary to secondary windings are isolated by their individual magnet wire coating.

If the transformer  leakage  (High Pot) manufacturing final test  across the isolation  barrier is @>30nA /@>50pF capacitance indicates the isolation primary to secondary is bridged  and it is rejected and destroyed.

Passing the HV test confirms the primary and secondary magnet  wire coating  does  not have   bridging between  windings .

Tom

Tom

JiaHuang:

I do not recommend  the HV high pot test  1second method  for any reason.

TI’s DCx series of DC/DC converters are all 100% production tested at their stated dielectric Voltage withstand test for 1 second .   

Repeated high-voltage isolation testing of a barrier component can degrade the isolation capability, depending on materials, construction, and environment. The DCx series of dc-dc converters have toroidal, enameled, wire isolation transformers with no additional insulation between the primary and secondary windings.

1.  However, if it is absolutely required, reduce the voltage by 20% from specified test voltage with a duration limit of one second per test.
2. 1. Once the MSL 3 package is open, it must be used within defined shelf life of 168 hours. . Prior to the next reflow processing, any remaining -unused converters must be dry packed and pre-baked (typically for 16 hours at 125°C when removed from the reel) for maximum reliability prior to the next reflow process. . The package must then   resealed with sufficient desiccant bags to maintain the MSL-3 level control at all times and prior to the next reflow process. any storage temperature30°C and or  humidity >60%  when not stored in compliance with MSL-3 requirements  requires new prebake per Jst 033C. Your unit will reuire a prebake of at least 23 -30days at 40°C in the T/R pack prior to reflow.
   2. Tom

JiaHuag:

Each DCP021212U is shipped from TI  with no damage to the transformer.

Any additional HV tests when installed and not complying with all MSL-3 controls and and procedures  prior to solder reflow processing may  protentially damage the.converters.

Repeated high-voltage isolation testing of a barrier component can degrade the isolation capability, depending on materials, construction, and environment. The DCx series of dc-dc converters have toroidal, enameled, wire isolation transformers with no additional insulation between the primary and secondary windings.

1.  However, if it is absolutely required, reduce the voltage by 20% from specified test voltage with a duration limit of one second per test.

1. Once the MSL 3 package is open, it must be used within defined shelf life of 168 hours. . Prior to the next reflow processing, any remaining -unused converters must be dry packed and pre-baked (typically for 16 hours at 125°C when removed from the reel) for maximum reliability prior to the next reflow process. . The package must then   resealed with sufficient desiccant bags to maintain the MSL-3 level control at all times and prior to the next reflow process. any storage temperature30°C and or  humidity >60%  when not stored in compliance with MSL-3 requirements  requires new prebake per Jst 033C. Your unit will reuire a prebake of at least 23 -30days at 40°C in the T/R pack prior to reflow.

Tom