Chemical Testing and Decapsulation for Counterfeit Detection

Where Chemical and Destructive Testing Sit in the Inspection Process

The AS6171 counterfeit detection standard organises test methods from least to most invasive. Visual inspection and X-ray are non-destructive and applied first. Electrical and parametric testing follows where risk warrants it. Chemical analysis and decapsulation are the final stage: more costly, and in the case of decapsulation, destructive. They are applied when earlier methods have not provided a conclusive result, or when the application risk is high enough to require die-level verification regardless of the earlier findings.

This sequencing is deliberate and economically rational. Not every lot warrants decapsulation. The decision to commission destructive testing is a risk-proportionate one: the higher the consequence of a missed counterfeit in the application, the further down the inspection sequence it is worth going.

Non-Destructive Chemical Methods

Before opening a component, several chemical analysis techniques can be applied to the exterior of the device and its leads. These are non-destructive and provide useful information about material authenticity without consuming the part.

X-ray Fluorescence (XRF) XRF is the most widely used non-destructive chemical technique in incoming inspection. It directs X-rays at the surface of the component and measures the fluorescent X-rays emitted by the elements present. The result is an elemental composition profile of the surface finish and termination materials. XRF is routinely used to verify RoHS compliance (detecting lead in supposedly lead-free terminations or vice versa) and to identify surface finish fraud. A component with tin-lead terminations sold as lead-free, or with a plating composition inconsistent with the manufacturer's specification, will be identified at this stage. XRF is fast, requires no sample preparation, and can be applied to the full lot without destructive consequence.

Fourier Transform Infrared Spectroscopy (FTIR) FTIR analyses the molecular composition of organic materials by measuring how the sample absorbs infrared light. Applied to component inspection, it is used to characterise the mold compound (the epoxy resin that forms the package body) and the die attach adhesive. A counterfeit component assembled from mismatched materials, or re-moulded in a different epoxy compound, may show a different FTIR signature from a genuine part. FTIR is also used to detect black topping: the additional epoxy layer used in remarking has a different chemical composition from the original mold compound and produces a distinct spectral result.

Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS) SEM provides high-resolution surface imaging at the microscopic level. EDS, used in conjunction with SEM, identifies the elemental composition of specific points on the surface. Together they are used to examine lead finish morphology, solder joint microstructure, and surface contamination in detail that optical microscopy cannot resolve. On an intact component, SEM-EDS can reveal evidence of re-tinning, abraded or re-applied markings, and surface treatment inconsistencies.

Decapsulation: Opening the Package

Decapsulation is the process of removing the IC package to expose the silicon die inside. Once the die is exposed, it can be examined visually under a microscope and compared against known-good die reference images to verify authenticity.

Chemical decapsulation uses fuming nitric acid, sulfuric acid, or a mixture of both to dissolve the epoxy mold compound without damaging the die or wire bonds. The acid reacts with the organic epoxy, removing it layer by layer until the die surface is exposed. The process requires controlled conditions, appropriate safety equipment, and handling by trained laboratory personnel. It is the standard method for plastic encapsulated devices (the majority of commercial ICs).

Mechanical decapsulation uses precision milling or grinding to remove the package material. It is used for ceramic packages and for devices where chemical decapsulation would attack the die surface or bond wires. Mechanical methods require more precision than chemical decapsulation and are applied less frequently.

Once the package is opened, the die is examined for the following:

Die markings and lot codes Authentic dies carry laser-marked identifiers: a part number, fabrication lot code, date code, and in some cases a foundry identifier. These markings are applied at the wafer level and are distinct from the package markings on the exterior. A counterfeit assembled from a different die will show markings inconsistent with the claimed part. A die with no markings, or with markings that do not correspond to the manufacturer's known format for that product family, is a strong indicator of fraud.

Die size and geometry Every semiconductor product has a characteristic die size determined by the circuit it implements and the process node it was fabricated on. An experienced analyst examining a decapsulated device can compare the die dimensions and layout geometry against reference data for the claimed part. A lower-specification product placed in a higher-specification package will typically have a visibly different die size and layout.

Die surface condition A recycled die that has been removed from a used component and repackaged shows characteristic surface degradation: bond wire stubs where the original connections were broken, surface contamination, and oxidation. These are visible under magnification and are not present on a genuine unused die.

Auger Electron Spectroscopy: Surface Elemental Analysis

Auger Electron Spectroscopy (AES) provides elemental analysis at the very surface of a material, with depth resolution in the nanometre range. Applied to decapsulated dies, AES can analyse the metallisation layers (the aluminium or copper interconnects visible on the die surface) and verify that their composition is consistent with the claimed fabrication process. It is used in specialist investigations where the surface chemistry of the die itself is in question, typically in high-stakes defence and aerospace applications where the suspicion is that a genuine die has been subjected to post-fabrication modification.

When to Commission Chemical and Destructive Testing

Not every procurement warrants decapsulation. The decision should be proportionate to the application risk, the supply source confidence level, and the findings of earlier inspection stages.

Chemical testing (XRF, FTIR) is appropriate as a routine layer for higher-risk purchases where material composition fraud is a concern: RoHS-critical applications, tin-lead process requirements, or lots where the package condition raises questions about remarking.

Decapsulation is warranted where earlier tests have identified anomalies but not provided a conclusive determination, where the application is safety-critical and die-level verification is required as a matter of policy, or where specific intelligence about known counterfeit types for that part number suggests die-level fraud is the likely risk.

A laboratory that routinely decapsulates every lot as a first step is applying destructive methods disproportionately. A laboratory that never decapsulates is not equipped to catch the most sophisticated counterfeits. The right approach is a structured sequence that escalates to destructive methods when the risk or the findings justify it.

What a Chemical or Destructive Test Report Should Include

A competent test report for chemical analysis or decapsulation should specify the method used and the conditions under which it was applied, the reference data used for comparison (known-good die images, manufacturer specifications, or published process parameters), the specific findings including photographic documentation of the die surface, markings, and any anomalies observed, the sample size tested, and a clear pass or fail determination per sample and per lot.

Photographic documentation of the decapsulated die is not optional. It is the evidence that the determination is based on what was actually observed, not an assertion. Before commissioning decapsulation, ask the laboratory for a sample report from a comparable investigation. A report without die photographs is not a credible counterfeit determination.

How Maketronics Applies Destructive Testing

For higher-risk requirements, Maketronics Assurance can commission chemical analysis and, where the risk profile warrants it, decapsulation through qualified inspection laboratories. We determine the appropriate level of testing based on the component type, the known counterfeit risk for that part, and the findings of earlier inspection stages. Results are documented before any shipment recommendation is made.

Sourcing a component from secondary channels where die-level authenticity matters? Talk to the Maketronics team about what Maketronics Assurance covers and when destructive analysis is the right step.