Faked Parts Detection
2010-08-22

Faked Parts Detection  

PoorBest Written by Lawrence W. Kessler and Thomas Sharpe   
      Thursday, 03 June 2010 18:46
      New Techniques to ID Counterfeit ICs
      Acoustic micro imaging can reveal whether the die and lead frame are
      genuine.

      SMT Corp. is an independent component distributor. To prevent counterfeit
      plastic-encapsulated ICs from reaching its customers, it uses multiple
      detection technologies, including visual inspection, light microscopy,
      digital stereo microscopy, resistance to solvents testing (RTS), scanning
      acoustic micro imaging, real-time x-ray, acid etch and mechanical
      decapsulation for die verification, solderability testing, BGA coplanarity
      inspection, scanning electron microscopy (SEM), energy dispersive
      spectroscopy (EDX), and x-ray fluorescence (XRF) inspection. Components
      identified by SMT as suspect-counterfeit are either turned over to federal
      law enforcement, government agencies, the IP holder, or ground up onsite
      and environmentally disposed.

      A practical necessity in any method of counterfeit identification is the
      availability of known genuine components of the same type. Except in
      instances of truly outlandish components (misspellings on the label, no
      die in the package, etc.), having genuine parts for comparative analysis
      makes counterfeit identification much easier, especially in components
      where some features fall in a gray area. (Are those delaminations
      extensive enough to prove counterfeiting, or are they just unusually
      sloppy work by the OEM?)

      Component users encounter two different types of counterfeit parts. By far
      the most common is the ※recycled§ ICs that began life, generally five to
      15 years ago, as a new, genuine component from a legitimate component
      manufacturer. Eventually the circuit board it resided on was scrapped and
      shipped offshore, where the entire component population was burned off for
      refurbishment, remarking, repackaging and reintroduction as new into the
      global supply chain. SMT Corp. estimates recycled ICs comprise 80 to 90%
      of all counterfeits currently in circulation worldwide.

      A small percentage of counterfeit components are ※made-from-scratch§ 每 or
      knock-offs. A foreign counterfeiter with component manufacturing
      capability finds it worthwhile to replicate the entire component
      altogether 每 and does so without the permission of the original IP holder.
      The chip and other internal features may be nonfunctional or even absent,
      or 每 worse yet 每 functional!

      The vast majority of recycled counterfeits undergo a process something
      like this: The board is heated in an uncontrolled harsh environment
      (usually an open-flame fire) until solder reflows, at which time the board
      is smacked against a hard surface to remove the components. The components
      from hundreds or even thousands of similar boards are collected and washed
      (sometimes in a nearby river, sometimes outside in the rain) to remove
      residue from the high-heat removal process, and then sun-dried. Most are
      then rough-sorted by sifting and then hand-sorted by part number or
      similar package style. In many cases, components of different
      manufacturers, vastly different functions and electrical characteristics
      wind up in the same finished counterfeit lot, as long as they have the
      same number of leads and the same package dimensions.

      The original component part markings are then removed (generally by
      rubbing the component by hand against sandpaper tacked to a table). A
      ※blacktop§ coating that more or less approximates the texture and color of
      the original mold compound surface is painted or sprayed onto the
      component*s top surface to cover the sanding marks. Last, the top surface
      is reprinted (remarked) with a legitimate-looking manufacturer*s logo,
      part number and more recent lot/date code. They are then packaged in what
      looks like (and may actually be) authentic original component manufacturer
      (OCM) packaging and offered for sale as new product direct from the
      manufacturer.

      The longevity of functioning counterfeits is, of course, questionable
      indeed. It should be pointed out, given the huge volume of containers
      recycled each year, that it is perfectly possible for the same component
      to be recycled multiple times. For the successful counterfeiter, external
      appearance of authenticity at the point of sale is what matters most;
      downstream functional issues become someone else*s problem.

      The efforts of counterfeiters to mimic the appearance of genuine
      components involve considerable innovation. While some methods are still
      crude, many are not.
      In July 2009, SMT Corp. was the first to identify a new, harder to detect
      blacktopping material that, when applied carefully, looked almost
      identical to the OCM*s top coating. Traditionally the paint-like
      blacktopping material has easily been identified by a solvent swab of pure
      acetone, or even a much milder 75/25% mixture of mineral spirits and
      alcohol. These solvents would dissolve the traditional blacktop coatings
      and reveal visual evidence left behind by the counterfeit process of
      removing original part markings.

      This new advanced blacktop material is harder to distinguish visually from
      the surface of a genuine part, and is not affected whatsoever by
      traditional RTS test methods. An engineer applying traditional solvent
      testing would conclude it to be a genuine part. SMT believes this advanced
      blacktop material is made from the dust ground off components and then
      mixed with a heat-activated epoxy compound before being sprayed on and
      heat-cured for hardness and durability. In September 2009, Honeywell
      Aerospace shared its process using a heated solvent called ※Uresolve§
      (made by Dynaloy) that proved effective in removing the new blacktop
      coating from counterfeit components. The only major drawback to the
      process was it also could remove the topcoat that OCMs put on the majority
      of authentic components. (Factory-applied topcoats, like the blacktopping
      that counterfeiters use, can be scraped off with a razor, but they hide no

      sanding marks.)

      In January, SMT Corp. further refined that process using a different
      Dynaloy product called DynaSolve 750. After considerable experimentation
      on a wide range of counterfeit and authentic parts, a temperature/duration
      process was identified that completely removed the new blacktop (exposing
      the sanding marks below) 每 yet had no effect on the factory-applied
      topcoats of all authentic components tested. The refined process required
      the DynaSolve be preheated to 105∼C and the suspect component to be
      half-immersed for 45 min. (Figure 1).


      These same components showed other signs of counterfeiting as well. For
      example, the highly engineered blacktop material had been sprayed onto the
      top surface, and some had visibly coated the upper portion of the side of
      the component. In addition, the blacktop material had in some cases been
      sprayed into the pin-one cavities, with the result that the cavities in
      close optical view appeared roughly textured rather than perfectly flat
      and smooth. Figure 2 is a SEM image of a portion of one pin-one cavity
      that has been partly sprayed. Some cavities, however, were completely
      clean and resembled those found in genuine parts.


      EDX analysis compared the results of the new blacktop material with
      analysis of the top surface of known genuine components. The results
      (Figure 3), while not identical, suggest it is possible that the
      sprayed-on blacktop had its origins in the dust created by sanding genuine
      components.
      Another clue was found in the leads of the components. At left in Figure 4
      is a light microscope view of two leads from a genuine component. Because
      these leads were straight when coated, the forming process produced some
      cracking or scaling of the coating at the bend. This is an expected
      feature on genuine components. But counterfeiters apply coatings to leads
      that are already bent, so cracking and scaling are absent. The coating
      applied by counterfeiters also rounds off the lead ends and conceals the
      copper base metal visible in the cut-off lead ends on the genuine parts.

 

      Most acoustic methods developed by Sonoscan use VHF or UHF ultrasound
      reflected from material interfaces at a depth of interest such as the die
      surface, the lead frame of die paddle surface, or the die attach depth.
      For example, when imaged acoustically, both genuine and counterfeit
      components treated with DynaSolve at 105∼C show some internal
      delaminations at the lead finger depth not present beforehand, an
      indication that the test should be
      considered destructive.

      The same C-SAM acoustic micro imaging system that images internal features
      can also image surfaces acoustically. It can also characterize a material
      at the same time it is making an acoustic image.

      One of the oldest methods for spotting possibly counterfeit components is
      the simple application of a single pulse of ultrasound to determine the
      mold compound*s acoustic impedance (acoustic velocity times density, the
      product expressed in megarayls). If known genuine parts have an acoustic
      impedance of around 4.3 megarayls, and an incoming part has an acoustic
      impedance of 7.6 megarayls, the new part may be a counterfeit, or the
      legitimate supplier may be using a new mold compound. One recent
      development: Some made-from-scratch counterfeiters are selecting mold
      compounds that attempt to match the acoustic impedance of the genuine
      component.

      During acoustic imaging of components, it is customary to scan the top
      surface of the part by itself for reference. The surface image gives no
      information about features at depth, but it turns out to have value in
      identifying counterfeits when the bottom surface, which is ordinarily not
      of interest, is also imaged. In genuine components, both surfaces appear
      identical acoustically because they were formed from the same material
      during the same injection molding process. But in a recycled fake where
      the top has been blacktopped, the two sides often look very different.
      (Figure 5).

      When an acoustic micro imaging system targets a specific depth within a
      counterfeit, strange things are sometimes found. Figure 6 shows two
      outwardly identical components having the body dimensions, the same label
      and the same number of leads. But the acoustic image shows that the
      component at bottom is either a newer die revision from the manufacturer
      utilizing a smaller die or is from a different component manufacturer
      altogether and uses entirely different die and lead frame. It also has
      small delaminations (red and yellow) on nearly all of the lead fingers.


      One of the areas of interest in any acoustic image of a component is the
      percentage of delaminations or similar defects in the die attach material.
      For example, J-STD-020D, sec. 6.2.1.1, specifies that metal lead frame
      components may have ※no delamination/cracking >50% of the die attach area
      in thermally enhanced packages or devices that require electrical contact
      to the backside of the die.§ New, genuine components may have some
      percentage of delamination and be perfectly acceptable for most
      applications. Recycled components may show a relatively greater degree of
      delamination, presumably because of the thermal and mechanical stresses of
      prior use and of the counterfeiting process itself. Figure 7 shows the
      acoustic image of a known counterfeit component whose die attach
      delaminations (red areas) exceed the standard. Digital image analysis
      showed delaminations covered 57.12% of the die attach area.

      It may be difficult to tell whether a particular component with above
      average die attach voiding is simply an isolated item from a good OEM, or
      whether this component has been heated irregularly, smacked on the ground
      and washed in a river. Determining whether a part is counterfeit is easier
      if multiple questionable parts and multiple known genuine parts are
      available in order to look for patterns. One group of counterfeits seen in
      Sonoscan*s laboratory had varying delaminations, some covering only part
      of the die paddle, and some extending onto the die face. The corresponding
      group of known genuine parts all had smaller delaminations, all on the
      same corner of the die paddle.

      Collaboration between SMT and Sonoscan has resulted in the identification
      of internal features not previously seen acoustically in components.
      Figure 8 is the acoustic image of a pair of components. The genuine part
      at top shows minimal defects. The recycled counterfeit at bottom shows
      numerous delaminations (red, yellow) on the die paddle and on the tape.
      But it also shows a surprising feature: two over-bright regions (arrows)
      near the bottom edge. Something has happened along this edge to make the
      interface between the mold compound and the lead fingers appear brighter
      than elsewhere, and the upper edge of this phenomenon is marked by a dark
      line. Two possible explanations: Sanding may have altered the top edge of
      the component, causing the returning ultrasonic echoes to bend; or heat
      may have re-cured or otherwise altered the mold compound in this region,
      but without creating a gap (delamination), which would be red or yellow.
      Strange effects seem to occur when components are subjected to heat,
      mechanical shock and moisture in uncontrolled environments.
      
      This brief article has not covered all of the techniques currently
      available to identify counterfeit components, but it demonstrates what may
      be accomplished with the innovative use of technological resources. Since
      counterfeiters are actively responding to detection methods, new detection
      methods will continually be developed to keep counterfeit parts out of
      production.

 
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