Tuesday, December 14, 2010 | Tom Adams, Consultant, Sonoscan, Inc.
Editor's Note: This article was originally published in the October issue of SMT Magazine.
BGA component (Figure 1) that is the subject of this article was
purchased from an open-market supplier by SMT Corporation, an
independent stocking distributor in Sandy Hook, Connecticut, as a
pre-purchase lot/date code sample of a much larger lot quantity being
considered. As part of SMT's robust counterfeit mitigation process,
technicians perform this pre-screening whenever possible to determine
authenticity and overall quality of a lot sampling before the full order
quantity is placed. If this component had passed the initial
pre-screening process, and if a full quantity order had been purchased,
all testing processes would have been repeated, even though the initial
lot samples had already been inspected.
Figure 1: The sample BGA that turned out to be counterfeit. Note the lot/date code information at the bottom.
walking through SMT's facility might easily conclude that the company
really consists of a series of well-equipped component inspection lab
areas surrounding large, spotless, humidity controlled warehouses. In
fact, the company is an independent stocking distributor that has been
forced by the increasing amount of counterfeit electronic components
being dumped into the open market to invest heavily in the latest test
and inspection technologies to protect customers.
are several main types of counterfeit components, by far the most
abundant are components that have been stripped off used PCBs (E-scrap),
refurbished, resurfaced and re-marked to reflect a newer single
lot/date code. They are then misrepresented and resold as original
factory-new product. Another common source for counterfeits is component
product that has been scrapped by the component manufacturer and that
has somehow made it into the hands of the counterfeiter. These
counterfeits may harbor internal surprises, such as missing or broken
die and bond wires.
are working harder to copy the new, original appearance of the
component manufacturers' surface finishes and part markings. In recent
years, these efforts have become much more sophisticated and difficult
to spot without expensive test equipment and proper training.
main market focus is supplying electronic components to the
hi-reliability industry needs of defense and aerospace, medical, energy,
telecom and other critical technology applications. It has in stock
over 120,000 line items of obsolete, hard-to-find and DMS-type component
products. SMT also serves as an authentication and quality lab for
OEMs, CMs and other open-market suppliers.
The various SMT laboratories use these methods to identify counterfeit components:
- Visual inspection: Light and hi-res microscopy;
- Data-sheet comparison, including mechanical measurements;
- Real-time X-ray;
- X-ray fluorescence (XRF);
- Energy dispersive spectroscopy (EDX);
- Scanning electron microscopy (SEM);
- Scanning acoustic microscopy (SAM);
- Automated solderability testing;
- Automated BGA co-planarity measurement;
- Resistance to solvents (RTS), including heated solvent testing;
- Acid-etch and mechanical decapsulation for die verification; and
- Electrical testing.
Sonoscan C-SAM® acoustic microscope system is a recent addition, useful
because ultrasound is reflected from internal interfaces between
materials—a capability that lets it image telltale internal signs of
counterfeiting. In its work with counterfeit plastic parts, Sonoscan has
imaged such items as misplaced die (in a made-from-scratch counterfeit)
and die face delaminations (in a "recycled" component that is near the
end of its useful life). In one part, it was the precise location of
wire bonds on a plastic-encapsulated die that revealed the counterfeit.
For decades Sonoscan's work has focused on finding internal defects,
characterizing materials and the like, but, in recent years, the menu
has expanded to include the identification of counterfeits.
first step in the SMT inspection of a component is visual inspection,
chiefly performed with visual inspection and light microscopy. Visual
inspection sounds simple enough, but technicians have learned so many of
the "red flags" that counterfeit parts exhibit that the check-off list
for light-microscopy visual inspection contains 23 distinct areas of
The first look at the BGA in Figure 1 raised a few
questions. Although the genuine National Semiconductor part had been
fabricated as a plastic package with a nickel top, the top surface of
the sample component had a color and texture that closely resembled
silver/gray paint. (Counterfeiters often resurface or "blacktop" a
component with a paint-like substance before re-marking it.)
inspection of the edges of the BGA raised suspicions even higher. When a
used component is spray-painted by the counterfeiter, some of the paint
typically winds up on the upper areas of the sides of the component.
2: Very strong evidence that the top surface has been spray-painted.
Excess paint can clearly be seen extending part of the way down the side
of the component.
At this point there was
essentially no possibility that this BGA was a genuine new component.
But it was worthwhile to continue the inspection process to find out
more about the counterfeit process used on the component and to try to
determine what its original identity had been. Figure 3: DynaSolve safely removed the paint applied by the counterfeiter.
next step was to immerse part of the component in a heated solvent
called DynaSolv™ (Figure 3). DynaSolve has the ability to remove
overlying paint or urethane coatings to expose the sanded surfaces
below. Figure 4: This SEM image clearly shows sanding marks on the plated nickel top of the BGA.
scanning electron microscope image made after the heated DynaSolve™
treatment and showing, at high magnification, the nickel surface of the
component and the adjacent bubbled-up edge of the remaining paint.
multiple scratch marks on the surface of the nickel are a clear
indication that the original component part markings were hand-sanded
off before the counterfeiter resurfaced the part with paint and then
remarked it with an ink-marking process.
There is now no
question about the history of this BGA. It was undoubtedly shipped from
the U.S., or another country, to China, packed in one of many containers
that deliver used PCBs (E-scrap) every day. The board, along with
hundreds or even thousands of other identical boards, then traveled to a
town such as Shantou, where workers toiling for low wages in primitive
conditions try to turn scrap electronic components into
cosmetically-acceptable fakes that can be passed off as new,
The process of removing used
components from scrap PCBs typically entails a worker holding a board
over an open flame or other heat source until the solder re-flows. At
this point, the board is slammed down on a hard flat surface causing the
components to drop off. Other workers gather up the components and take
them to the next process—washing to remove the soot residue from the
heating step. Incredibly, most components are washed by dunking them
into nearby rivers and streams or spreading them on sidewalks in the
rain. Later they are sorted, often by young children and elder women.
Sorting is carried out according to the specific package type of a
component and the number of leads. What this means is that all ICs
having the same x-y dimensions and having, for example, 16 leads go in
the same pile. After washing, the components are taken into multi-story
buildings that double as homes, where the sanding and remarking process
take place prior to resale. (In a 2008 trip to China, Tom Sharpe, Vice
President of SMT Corporation, photo-documented these crude processes
first-hand while touring the counterfeiting districts of Shantou.)
are undoubtedly vast differences in the die revisions, year of original
manufacturer, performance capabilities and overall functional lifespan
of these parts, but after their cosmetic rebirth they will all carry the
same lot/dc labeling and will be represented and sold as though they
were a new, unused homogenous lot.
5: An optical close-up view of the BGA after heated DynaSolve™
treatment. Most of the paint has been removed, and the shiny, sanded
surface of the nickel plated top is visible.
original labeling on this component, it turns out, was applied by laser
etching. In the upper part of Figure 5, a small part of the counterfeit
ink-printed logo is visible to the right, and to its left an etched
portion of the original logo is still faintly visible in the nickel. The
purpose of sanding was clearly to grind off enough nickel plate to
remove the traces of the original laser etch part marking. It is
possible that the worker doing the sanding was told to remove the
etching, but not to go much deeper because he would then create a
component that was suspiciously thin (SMT mechanically measures
component critical body dimensions with digital calipers as part of
their counterfeit mitigation process), although the paint that will be
applied after sanding will increase the thickness. As it turned out, the
worker did not go quite deep enough and, by doing so, left behind
additional evidence for investigators. The optical image in Figure 5
shows some of the laser-etched logo in the nickel, but the copyright and
lot/dc that are normally seen at the bottom of the part in Figure 1 are
no longer visible to the naked eye.
This is where acoustic
microscopy came in handy. An acoustic microscope pulses VHF or UHF
ultrasound into a part from a raster-scanning transducer. The distance
to internal features in the part is short and the speed of ultrasound is
high, with the result that return signals (echoes) can be received from
thousands of x-y locations per second. The return signals can be
processed in various ways, but most often the amplitude of the signal
determines the color of the pixel in the acoustic image.
acoustic image can also be confined vertically to a desired depth within
the component. In general component inspection work, for example, this
might be the die face depth, the die attach depth or the lead frame
depth—all of which include material interfaces. It even images, from the
back side of advanced flip chips, cracks in the exceedingly thin low-k
dielectric layers. If required, the return echoes can provide images of
up to 100 different depths from the same scan.
At any point in
the scanned depth, there are three possibilities: 1) ultrasound
encounters no material interface and sends back no echo; the pixel is
black; 2) ultrasound encounters a bonded interface between two
materials; the pixel is some shade of gray; 3) ultrasound encounters the
interface between a solid and a gap such as a crack; the pixel is
In the case of this BGA a
single, somewhat unusual depth was selected, ranging from the top
surface of the nickel to a fraction of a millimeter below the top
6: Acoustic microscopy of the sanded surface and immediate subsurface
shows that the lot/date code information ink-printed on the BGA (Figure
1) was a fake.
As it turned out, sanding
removed visual evidence of the original markings, but not acoustic
evidence. Most likely the original manufacturers' laser etch process
changed the acoustic properties of the nickel beneath the laser cut
itself, with the result that ultrasound encountered two slightly
different materials: unaltered nickel and altered nickel. The bottom
image in Figure 6 shows an acoustic image containing the originally
marked copyright and manufacturing on the top line, followed on the
bottom line by manufacturing codes denoting country of assembly, lot/dot
code, wafer lot and die-revision among other things. The top image in
Figure 6 shows the similar paint re-marking code that was selected by
the counterfeiter for this particular lot from Figure 1. Rectangles show
the critical difference between the two. The genuine lot/dot code and
wafer lot revision was "302AF;" the counterfeited version has been
changed to "251AH." (For reference, "302" is the year/week code of
manufacturer—2003, second week of the year, while the "AF" stands for
the wafer lot the die contained inside was taken from. The "A2" at the
end is the die revision.)
This was a somewhat unusual
application of acoustic imaging, which more often looks deeper into
components to analyze internal features. But acoustic microscopes can
use ultrasound in other ways; for example, to characterize a mold
compound by measuring its acoustic impedance, or to nondestructively
cross-section a component. Dr. Lawrence Kessler, President of Sonoscan,
notes that the company's SonoLabs have already compiled a list of
internal acoustically visible features that are specific to
counterfeits. The list is somewhat parallel to, and about the same size
as, SMT's list of 23 items for visual inspection. For the inspection of
this BGA, acoustic imaging uncovered the original specific identity that
the counterfeiters had worked so hard to conceal.
Sonoscan is a registered trademark of Sonoscan, Inc. DynaSolve™ is a trademark of Ellsworth Adhesives.