Wednesday, January 16, 2013

USBid Counterfeit Alert - HA7-5137A-5

During the past few months, USBid has purchased several lots of an Intersil, Low Noise Op-Amp, p/n HA7-5137A-5, from different sources - two of the three orders included counterfeit product mixed in with good devices. This report will describe the detection methods used to discover the fraudulent product and summarize the findings.


Overview

Per the data sheetthe HA7-5137A-5 is a precision op-amp from a family that includes HA7-5127, 37 and 47 devices; all are offered in 8 pin Ceramic DIPs with identical pin outs, performance similar to an OP270, with the following specifications:
   Parameter
Slew Rate Gain Bandwidth Offset     Voltage    Noise
Device (Volts/uSec)      (MHz)   (uVolts) (nV/Rt Hz)
HA-5127A      10      8.5      10      3.0
HA-5137A      20      63      10      3.0
HA-5147A      35      120      30      3.2




Test and Inspection


Initial product purchased from an approved vendor appears below and was subjected to a complete suite of AAA Component Test Lab Inspection and Test Services, including electrical testing of all 100 units.
Figure 1. HA-5137A Purchased from Approved Vendor

The product passed and was sent to the customer with no reported problems. The second batch of product came from another source and went through the same procedure. The visual appearance was similar to the above and visual inspection and Resistance to Solvent tests found no non-conformities.
Figure 2. HA-5137A Purchased from Unapproved Vendor

During electrical testing however, ~ 25% product began to fail and a physical decapsulation of several of the passing and failed dice from the ceramic DIP revealed two different devices. We didn't expect to see two different  passing devices - usually the passing de-capped units are consistent in appearance....


Figure 3.  HA-5137A Device 1

Figure 4. HA-5137A Device 2
Subsequent evaluation of the obvious visual differences between the two failed devices showed that the die in Figure 3 was actually a HA-5127 as seen in Figure 5.


Figure 5. "HA-5137A" was actually a HA-5127 device.

The die photo in Figure 4 was similar to the photo from the approved supplier we previously purchased product from and closer inspection revealed expected HA-5137 die markings as shown in Figure 6.
Figure 6. Failed HA-5137A Die Markings Up Close

So we now have multiple problems - counterfeit HA-5137A and authentic devices that both pass and fail pin correlation testing.  How do we sort out the defective product? How do we cull the HA-5127's that pass pin correlation testing?  The first step was to develop a comprehensive DC functional test that distinguishes HA-5127's from HA-5137's. From the Parameter Table above, the Gain Bandwidth spec was the most drastically different parameter between these two devices. This test would remove all devices of both part types that didn't meet this specification.

Once the Gain Bandwidth testing was done, the passing parts were subjected to another round of pin correlation testing - a small percentage (<1%) still failed the test. The  pin correlation test was set up to match our customers incoming test procedures - if the parts failed their test they were rejected regardless of data indicating otherwise. 


Conclusion

Pin Correlation testing provides certain insights to gross functionality performance but can also produce incorrect assumptions that functional testing can alleviate. To satisfy customer requirements, USBid pulled (and assumed liability for) the "failed" parts from the pin correlation testing and shipped the rest. The customer reported 0% incoming failures and 0% final product failures for these parts. Further analysis of the counterfeit HA7-5137A's (i.e. - the ones with the HA-5127 die) revealed that the bottom markings shown in Figure 2 were all from a few specific date codes that didn't match Intersil's nomenclature.


Happy Customer = Happy Ending


About USBid
USBid is an independent distributor of electronic components located in Palm Bay, Florida, USA. Since 1998, we have been helping customers locate and purchase hard-to-find and long lead time components. We are AS9120:2009 and ISO 9001:2008 certified and ESD S20.20-2007 compliant. We provide comprehensive visual, physical, and chemical analysis of all orders including electrical parametric testing to manufacturer datasheet specifications when applicable. For more information, checkout our USBid Overview on YouTube.





2 comments:

Anonymous said...

Thanks for the notice on these parts....Has USBid seen more of these counterfeits?

Gary Heyes said...

Not that same part, no, but we did see some counterfeit HA7-5147A-5. De-cap showed them to be HA-5127A die.