New Counterfeiting Blacktopping Technique

By Sanjay Chawla On Feb. 24, 2010 Site: Electronics Design Engineering Lounge (Public) Type: Blog - Tags: Electronics - # of views: 11182

SMT closely studied the new blacktopping material surfaced on counterfeit Xillinx parts sent by a North American broker to them and identified following:

1. Visual Appearance - the visual appearance of the counterfeit blacktop compound is almost identical to a known good Xilinx that was just purchased from an Authorized Franchised Distributor.
2. Surface Texture - although similar visually, the texture of the new blacktop material has a slightly rough "sharkskin" or "orange peel" gritty texture to it as compared to the smoother feel of an authentic component surface.
3. Resistance to Solvents - pure acetone has zero affect on the blacktop compound.
4. Resistance to Heat - very high heat resistance to open flame - similar to surface of known authentic part.
5. X-Ray Fluorescence (XRF) - very similar readings in analytical mode although Bismuth was found in amounts 4-6 times higher in the blacktopped part (Bismuth is highly resistant to solvents and heat. Although it has many other uses, it is commonly used in semiconductors and paints.)
6. Energy Dispersive Spectroscopy (EDS) - the element makeup of the new blacktop material surface displayed in EDS color mapping mode is very similar to the surface composition of the known authentic part.
7. C-mode Scanning Acoustic Microscopy (C-SAM) - the 50 MHz surface scans of both components produced an interesting contrast variation on the counterfeit top surface only.

After closely observing the particles scraped from the surface of the blacktopped part, it suspect that the blacktopping compound is manufactured by retaining the sanding dust generated from sanding the top surfaces off the components and then blending it with a heat activated bonding compound - containing Bismuth among other things. (Using the dust over again to create a new top-coating would significantly replicate the similar results gotten from both surfaces in the XRF & SEM-EDS testing.)

By the looks of the evenly-applied coating and overspray particles found on the counterfeit devices, the blacktop material must be being applied with a powder-coating type spray gun apparatus and then immediately baked to permanently bond it to the sanded surface of the chip. This process would make it virtually immune to removal by any solvent swipe testing.

When this blacktopping is carefully applied in such a way that leaves the component free of any overspray and the Pin-1 dimples clean and free of blacktop material as well, you end up with a blacktopped surface that many if not most QC technicians will miss after it stands up to an acetone swipe.

Bear in mind after viewing that this can just as easily be applied to new parts that have factory-fresh leads or possibly new parts from the same product families that are much older, rated at slower speeds or only rated for commercial applications. The real threat here has to do with the fact that the vast majority of quality inspection technicians are currently hanging their hats on a vigorous acetone swipe test.

Please view the detailed PowerPoint presentation attached. There is a lot of very good information here that I am sure you will find quite interesting - and most concerning.

Attachments:

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	Engineered-Blacktop-Material-Analysis-SMT-Corporation-PP-08-27-09.pdf 9.21 MB