The number of counterfeit semiconductors being introduced into the supply chain is on the increase, and as the numbers increase, so does the sophistication of the counterfeiters themselves. Military and space OEMs and small volume manufacturers, faced with procuring obsolete or allocated devices via the open market, are now challenged with the problem of how to effectively detect counterfeit semiconductors. These companies are now compelled to put processes in place to ensure counterfeit devices do not make it to their production line. The processes defined must ensure detection, but also balance the cost and lead-time issues associated with destruction of precious components and non-recurring engineering (NRE) cost and testing. Devices can be either factory sealed, or repackaged. Generally, the inspection processes are not intended to inspect used parts. Used parts, sometimes known as “board-pulls”, are automatically suspect and will be rejected according to accepted inspection practices. Sophisticated counterfeits or OEM rejects cannot be detected by an external, physical inspection process. Advanced testing methods such as AC/DC electrical tests, or de-capsulation and die inspection are required to identify sophisticated counterfeits.
A first-line suite of tests has been identified by the EMPF which can be used to identify counterfeit integrated circuits for quick turn requirements. Using this procedure, limited qualification testing can be performed on suspected counterfeit ICs. The testing methods and inspection methodology that are currently being used for counterfeit detection are in part derived from the following documents:
- IDEA-STD-1010-A “Acceptability of Electronic Components Distributed in the Open Market”, The Independent Distributors of Electronics Association (IDEA)
- JESD22-B107C Marking Permanency Test, JEDEC Solid State Technology Association
- MIL-STD-883E Department of Defense Test Method Standard Microcircuits
Additionally, the EMPF provides more in-depth analysis of more sophisticated counterfeits including de-capsulation, die inspection by SEM/EDS, and electrical testing through industry partners. The following testing and inspection methods have been selected for the quick-turn counterfeit detection process.
A visual inspection is performed on a sampling of devices from a given lot. The magnification is adjusted as required to inspect certain features of the part. Device markings and dimensions are compared with the manufacturer’s datasheet for authenticity. The lead finish is examined for evidence of previous use or refinishing. The body of the device is examined for evidence of improper handling or previous use. With more sophisticated counterfeits, a visual inspection is often insufficient. Being able to look inside the package is often required. De-capsulation is destructive, but X-Ray inspection is non-destructive and can reveal many hidden features.
X-Ray inspection is performed on each device to confirm the presence of a die. Counterfeits are sometimes packaged without a die (Figure 6-1) or with a different die. Finding a different die does not necessarily indicate a counterfeit since manufacturers sometimes will institute a process change on a particular product, but the parts would not have the same date code. Note that the resolution of X-Ray imaging is not yet sufficient to resolve markings on the die surfaces to authenticate the device (Figure 6-2).
X-ray fluorescence inspection (XRF) is performed on the leads to confirm whether the material composition of the finish on the leads has lead or is lead-free. This technique is useful for determining if a counterfeit component has been marked ROHS compliant when it actually contains lead.
The purpose of this inspection is to find evidence that the devices have been remarked. Remarked parts sometimes make use of ink that does not withstand the solvents used in board assembly manufacturing processes (Figure 6-3 compared to Figure 6-4). The marking permanency test is used to determine if the IC ink marking is resistant to solvents. Remarking, using either laser marking or ink marking, requires resurfacing of the component to remove evidence of the original mark. The resurfacing test inspects for evidence of alterations to the component body. Evidence of sanding is often hidden by resurfacing. This test chemically cleans the body of the part and removes the resurfacing material. The part is visually inspected after cleaning for evidence of sanding. This is a destructive test.
Information from component vendors is required to perform the visual inspections of this process. Access to this information for an obsolete part is sometimes limited. A few on-line resources are available to help bridge this information gap.
- www.icphotos.org Free data base that has photos of many integrated circuits
- www.chipdocs.com Subscription service to a datasheet database
- www.datasheetcatalog.com Free datasheet database
- www.jedec.org JEDEC Solid State Technology Association
- www.gidep.org Government-Industry Data Exchange Program (GIDEP)
- www.erai.com Electronic Resellers Association International Inc., (ERAI)
- http://www.idofea.org The Independent Distributors of Electronics Association (IDEA)
The first-line suite of testing and inspection methods described above has been useful for a quick-turn counterfeit detection process. Using these procedures, limited qualification testing can be performed on suspected counterfeit ICs. The EMPF also provides more in depth analysis of more sophisticated counterfeits including de-capsulation, die inspection by SEM/EDS, and electrical testing through industry partners. If you are currently buying electronic components from independent brokers or from a new source, consider qualifying your orders to assure that you are not receiving counterfeit parts.