The inspectors in the USBid, Inc. AAA Test Lab use a wide range of techniques to detect counterfeit parts. Some techniques are complicated with intricate testing procedures and specialized equipment like the solderability test or x-ray detection. Other techniques are often overlooked by other test labs because they are simple to do. However, even simple tests provide crucial data for inspection.
One such easy check is a mechanical inspection of the packaged device using a digital calipers.
Here’s how the mechanical inspection works.
Taking the Measurements
First, the inspector makes sure the inner measuring surfaces of the digital caliper device is free of any foreign matter and reads “0.000” when completely closed.
Next, the inspector measures the electronic component. At a minimum, the following six dimensions should be measured:
Length: The distance between ends or the long dimension of the component.
Width: The dimension from side to side.
Height: Measurement of total vertical distance.
Body Thickness: Vertical distance of the device body – diagonally and end to end.
Lead Pitch: The center-to-center distance between 2 leads.
Lead Width: The measurement of the width of 1 lead.
Compare the Measurements
Once the measurements have been taken, the inspector compares the measurements with the product data sheet. Most semiconductor manufacturers include the package dimensions on product datasheets and companies like Texas Instruments provide a detailed section of their website to physical package data.
The data should be compared to relevant data from the manufacturer; if the product has a 2006 date code, then the inspector compares it to a datasheet that precedes that date by as little as possible. The AAA Test Lab inspector compares the measurements taken with manufacturers specifications, incorporating the specified tolerances for each of the above parameters. If all measurements are within spec, the part conforms.
Watch for Thickness Variation
In addition to comparing the measurements to the data sheet, the inspector will also watch for thickness variations. When the inspector measures diagonally and from end to end, there should be (almost) no variation between the two. Any slope or unevenness in the thickness can be the result of sanding.
Counterfeit devices have been sanded to remove the original marking from the component, and then a thin layer of blacktop is applied to make the part appear shiny and prepare it for remarking. Remarking can be done to upgrade the part to a higher performance level, give the part a newer date code, or remark it as a completely different product with the same package type. If the inspector suspects the parts may be remarked, they will check at least 5% of total quantity. There should not be more than a 1% part to part variation between any of the six measurements.
Protect Your Project from Counterfeit Parts
Mechanical inspection, along with simple solvent tests, provide an effective, quick means to determine if the device being tested might be counterfeit and positive results (part fails test) from either can save you time and money. However, negative results are not necessarily grounds for assumption that the parts are authentic as much more rigorous testing is required. That’s why our inspectors perform so many different tests on every part in our online catalog. You can order with confidence from USBid, Inc. knowing that our attention to detail has qualified us for QTSL/QSLD certification.