This guide covers: the AS6171 standard framework for counterfeit detection (CONTEXT), visual inspection with marking and package criteria (POINT 01), X-ray inspection — 2D and 3D CT (POINT 02), electrical characterisation testing (POINT 03), decapsulation methods and die verification (POINT 04), chemical analysis techniques — XRF, EDS, FT-IR (POINT 05), acoustic microscopy (C-SAM) and thermal analysis (POINT 06), the four-level inspection prioritisation framework (POINT 07), and incoming inspection process management (POINT 08).
AS6171 is the SAE International standard suite governing test methods for detection of counterfeit electronic parts. It defines the technical basis for inspection programmes across aerospace, defence, industrial, and high-reliability commercial supply chains — and provides the testing methodology that AS6081-certified independent distributors are required to apply. The standard is structured as a base requirements document with specific test-method sub-parts covering every major detection technique.
AS6171/1
General requirements — programme structure and documentation
AS6171/2
Visual inspection — marking, package, leads, dimensions
AS6171/3
X-ray fluorescence (XRF) — elemental composition
AS6171/4
DPA — destructive physical analysis
AS6171/5
Radiological — 2D X-ray and 3D CT
AS6171/6
Acoustic microscopy (C-SAM)
AS6171/7
Raman spectroscopy
AS6171/8
FT-IR (Fourier transform infrared)
AS6171/9
Thermal analysis (DSC, TGA)
AS6171/10
Electrical testing (DC, AC, functional)
AS6171/11
Decapsulation — die exposure and inspection
Detection philosophy: No single test method reliably identifies all counterfeit types. A sophisticated counterfeit may pass visual inspection, X-ray, and even basic electrical testing while failing chemical analysis or die inspection. The systematic approach is to begin with non-destructive tests (which can be applied to all samples) and escalate to destructive tests (applied to samples) when anomalies are found at any non-destructive stage. The objective is to accumulate corroborating evidence across multiple independent tests — multiple consistent anomalies make a definitive determination even without a confirmed genuine reference sample for direct comparison.
Visual inspection is the first line of detection — fast, zero-cost for basic examination, and effective at identifying common counterfeit types including re-marked (relabelled), resurfaced, and cloned components. The core technique is side-by-side comparison of suspect parts against confirmed genuine reference samples under magnification (10× to 40× for initial screening; up to 200× for detailed marking examination).
Marking Anomalies — What to Look For
Blurred or inconsistent text weight — genuine laser-marked text is sharp and uniformly engraved; ink-printed marks on re-marked parts are often blurred or uneven
Incorrect font style or character spacing — manufacturer fonts are proprietary and consistent across genuine lots; cloned parts often use similar but not identical fonts
Overlapping markings — re-marked parts often show traces of the original marking beneath the new one, visible under angled lighting or UV
Date code implausibility — any component with a date code predating the device's introduction year is definitively suspect; lot code format not matching manufacturer convention
Markings that rub off — genuine laser engravings are permanent; ink applied over a resurfaced package will smear under light friction with a cotton swab and acetone
Sanding or polishing marks on package surface — re-marking requires removal of the original marking, which leaves micro-scratches visible under magnification and raking light
Package and Lead Condition
Examine the package body for: inconsistent mould finish quality (genuine packages from a single lot have identical surface texture; mixed sources show variation), mismatched gloss level between body and mould lines, coating or paint applied over the original surface, and inconsistent package dimensions or weight versus datasheet specifications.
Lead and pin inspection: re-plated leads have a characteristically different surface texture, colour, and reflectivity compared to original plating. Residual solder on leads indicates prior board mounting — the component was desoldered and reprocessed. Lead oxidation inconsistent with the claimed age and storage conditions indicates either long open-air exposure or prior use.
Scanning Electron Microscopy (SEM) extends visual inspection to the micron scale — revealing engraving depth, plating grain structure, and surface treatment features that optical microscopy at practical magnifications cannot resolve. SEM is used for detailed confirmation of visual anomalies found at lower magnifications, not as a primary screening tool.
X-ray inspection transmits radiation through the package and creates an image of the internal metallic structures — the die, lead frame, bond wires, and any metallic features inside the encapsulant. It is the most information-rich non-destructive technique available and should be part of standard incoming inspection for any component from a non-authorised distribution source.
2D X-RAY
Projection imaging of internal structure
Standard 2D X-ray produces a projected image through the package showing die, lead frame, and bond wires. Capable of very high throughput with automated systems. Compare against reference X-ray images of confirmed genuine parts for the same part number — anomalies in die size, bond wire count, or lead frame design are immediately apparent in side-by-side comparison.
Detects: absent die, wrong-sized die, wrong bond wire count or routing, incorrect lead frame design, internal metal mass anomalies, previous-mounting solder residue inside.
3D X-RAY CT
Volumetric tomography — full 3D reconstruction
3D computed tomography acquires images from multiple angles and reconstructs a volumetric model of the component interior. Enables cross-sectional analysis at any plane — including features obscured in 2D projection. Slower and more expensive than 2D; applied to specific items where 2D findings are inconclusive or where the package geometry requires volumetric analysis.
Detects: BGA solder ball internal voids and cracks, multi-layer package internal structure, complex 3D wire routing anomalies, delamination not visible in 2D projection.
Building a reference X-ray library: The most effective use of X-ray inspection requires comparison against reference images of confirmed genuine parts. Maintain a reference library of X-ray images for every high-criticality part number in your BOM — sourced from the authorised distributor's first delivery. Without a reference, X-ray findings must be evaluated on absolute criteria (die present/absent, bond wire count matches datasheet) rather than the more sensitive comparative assessment that reveals subtle differences in die dimensions and lead frame design.
Electrical testing confirms whether a component performs to its datasheet specification — which is the functional definition of authenticity for most applications. Counterfeit parts frequently fail electrical testing even when they pass visual and X-ray inspection, particularly cloned parts using inferior die or downgraded components remarked to a higher specification.
DC CHARACTERISATION
Static electrical parameters vs datasheet
Measures fundamental DC parameters against datasheet specifications: supply current, input/output voltage thresholds, leakage currents, breakdown voltages, on-state resistance, and any other DC parameters specified in the component's absolute maximum ratings and recommended operating conditions.
Detects: significantly inferior die substituted for original, out-of-specification devices remarked to higher spec, parameter degradation from electrostatic damage or prior use.
AC / DYNAMIC TEST
Switching speed, frequency response, noise
Measures dynamic parameters: propagation delay, rise/fall times, frequency response, output slew rate, phase noise (for oscillators), and any timing parameters specified in the datasheet. AC parameters are harder to counterfeit than DC — a substitute die from a different process node or manufacturer will typically fail AC specifications even if it passes DC characterisation.
Detects: wrong-technology die (different process node), speed-graded devices remarked as faster, timing anomalies from process differences.
FUNCTIONAL TEST
Protocol, instruction set, full operation verification
Exercises the component's defined functions at operational conditions: memory read/write across all address/data combinations, MCU instruction execution, communication IC protocol compliance (I²C, SPI, UART, CAN), signal processing functions for DSPs. Functional discrepancies between the component's behaviour and its datasheet specification are strong evidence of either a different device or a deliberately impaired device.
Detects: different device from different manufacturer in same package, partially functional die, software-locked or region-locked devices, reprogrammed parts.
TEMPERATURE TEST
Verify rated operating temperature range
Tests all relevant parameters across the full rated temperature range — at minimum, at the low temperature extreme, at room temperature, and at the high temperature extreme. A commercial-grade device remarked as industrial or automotive grade will fail specifications at the extended temperature limits even if it passes room-temperature testing. Temperature testing is essential for parts being used in automotive or industrial applications.
Detects: commercial-grade parts remarked as industrial/automotive/military grade, devices with inadequate temperature compensation, thermal failure modes below rated maximum temperature.
Decapsulation is the removal of an IC package's outer encapsulant to expose the semiconductor die inside. It is a destructive test — the component cannot be returned to service after decapsulation — so it is performed on samples rather than 100% of a lot. It is, however, the most definitive technique available short of full die reverse engineering: no counterfeit manufacturer has access to the authentic die design, making the die itself the highest-confidence authentication token.
Three Decapsulation Methods
METHOD 1
Mechanical decap
Progressive grinding of the package material while leaving the lead frame intact and accessible. Lower technical barrier than chemical decap. Risk of die mechanical damage during grinding if layer depth is misjudged. Appropriate for initial screening where die surface markings only are needed.
METHOD 2
Chemical decap (acid)
Concentrated sulfuric acid or fuming nitric acid dissolves the epoxy encapsulant selectively while leaving metallic die and lead frame intact. Requires specialist safety infrastructure and process control. Produces cleaner die exposure than mechanical decap for optical and SEM examination. Most widely used in professional test labs.
METHOD 3
Plasma decap
Oxygen plasma selectively removes organic encapsulant material at the molecular level without the acids, temperatures, or physical forces of the other methods. Minimal die surface damage — preferred when the die surface condition is critical (e.g., for electrical re-probing after decap). Higher equipment cost; slower throughput than acid decap.
What to Examine on the Exposed Die
After exposure, examine the die under optical microscopy (100×–500×) and SEM as required:
🔬Die markings — manufacturer logo, part number, revision, lot
The die surface of genuine parts carries the manufacturer's logo, part or internal revision code, and often a manufacturing date or lot code — placed during wafer fabrication and impossible to replicate without access to the original mask set. A die bearing the wrong manufacturer name, a different internal code, or no markings is definitive evidence of counterfeiting.
📐Die dimensions and overall shape
Measure the die length and width and compare against reference values from confirmed genuine samples or published die size information. A counterfeit using a substitute die will almost always show a dimension difference — die sizes are determined by the circuit layout and cannot be adjusted without mask redesign.
⚡Circuit layout topology
The high-level circuit layout visible at optical magnification — pad ring arrangement, internal block structure, power routing topology — is unique to each device and can be compared against reference images. Major layout differences are visible even without the detailed transistor-level analysis of full reverse engineering.
🔗Bond wire number and routing
Count and map the bond wires connecting die pads to lead frame pins and compare against reference. The bonding map for a genuine device is defined and consistent. Incorrect wire count, non-standard routing, or wires connecting unexpected pad positions are diagnostic of a substitute die.
XRF
X-ray fluorescence — elemental composition
Irradiates the component surface with X-rays; analyses emitted secondary X-rays to determine elemental composition. Non-destructive. Provides bulk composition of the analysis area (typically 1–5 mm). Applied to lead plating, package surface, and any metal feature accessible for measurement.
Detects: re-plated leads with different metal composition, lead (Pb) presence in components claimed as RoHS-compliant, solder residue composition from prior use indicating board-pulled components.
EDS / SEM-EDS
Energy dispersive X-ray — localised elemental mapping
Combines with SEM to provide elemental composition analysis at the micron scale — mapping elemental distribution across a specified area or point-analysing a specific feature. More spatially precise than XRF, enabling analysis of individual plating layers, bond wire composition, die metallisation, and contamination at specific locations.
Detects: plating layer composition differences at bond pad interfaces, wire bond material anomalies (Al vs Au vs Cu wire), die metallisation material differences indicating a different manufacturing process.
FT-IR
Fourier transform infrared — organic material identification
Measures infrared absorption spectrum of organic and polymer materials, identifying chemical functional groups and enabling material identification by library matching. Applied to package encapsulant, lead coating materials, adhesives, and any organic surface coating. Non-destructive for surface measurements; requires a small sample for transmission measurement of bulk material.
Detects: wrong encapsulant resin formulation (different manufacturer or grade from genuine), coating applied over the original package surface, adhesive material mismatch indicating previous rework or repackaging.
DSC / TGA
Thermal analysis — material characterisation
DSC (Differential Scanning Calorimetry) measures heat flow as a function of temperature, identifying glass transition temperature (Tg), melting points, and cure state of polymer materials. TGA (Thermogravimetric Analysis) measures mass loss with temperature, characterising decomposition behaviour and filler content. Both are destructive — applied to small material samples extracted from the package.
Detects: wrong encapsulant material with different Tg, incorrect resin formulation, moisture content inconsistent with storage history, material substitution detectable through different thermal decomposition profile.
C-SAM — Scanning Acoustic Microscopy
C-SAM (C-mode Scanning Acoustic Microscopy) uses focused ultrasound — typically in the 15–300 MHz range — to image internal interfaces within the component package. Ultrasound reflects at every interface between materials with different acoustic impedance, and at voids where no material exists. The reflected signal is mapped to produce a 2D image of internal interface condition at any selected depth.
C-SAM: WHAT IT FINDS
Delamination, voids, cracks, and moisture damage
C-SAM detects separation (delamination) between the die attach layer and lead frame, between die and encapsulant, or between internal package layers. It also detects voids in the encapsulant or die-attach material, and microcracking from thermal or mechanical stress. These defects are invisible in visual inspection and X-ray but show clearly in acoustic images.
Detects: board-pulled components with internal delamination from prior solder reflow, moisture-induced popcorning damage from improper handling, cracking from previous thermal stress cycles — all characteristic of recycled or reworked components.
C-SAM: BEST USE CASE
Identifying recycled or board-pulled components
Components desoldered from boards and reprocessed for resale as new frequently carry internal damage from the desoldering thermal cycle that is undetectable by visual inspection, X-ray, or electrical testing — but clearly visible in C-SAM images as delamination at the die-attach interface or fine cracks in the package encapsulant. C-SAM is non-destructive and can be applied to 100% of a suspect lot before electrical testing, protecting test sockets from damaged parts.
Identifies recycled/board-pulled components that would otherwise pass visual, X-ray, and basic electrical testing.
Die Reverse Engineering — Definitive Authentication at Maximum Cost
Full die reverse engineering — layer-by-layer delayering (layer stripping) with SEM imaging of each exposed layer, followed by circuit extraction and comparison against the known authentic die topology — is the most definitive authentication technique available. It confirms not just that a die is present and correctly sized, but that its internal circuit architecture is identical to the genuine device.
Layer delayering uses chemical etching or ion beam milling to progressively remove each metal and diffusion layer, photographing each layer before removal. The resulting stack of layer images is compared against reference layer images from confirmed genuine parts. This process takes several days to weeks and costs thousands of dollars per component — justified for high-value, safety-critical, or high-volume components where definitive authentication has a proportionate ROI.
Die reverse engineering services are provided by specialist semiconductor analysis companies (Chipworks/TechInsights, Fraunhofer, and others). For most procurement organisations, it is an outsourced capability used for definitive resolution when other tests produce inconclusive results.
Applying every available test to every component lot is neither practical nor cost-effective. The four-level framework below matches inspection depth to risk profile — source risk, component criticality, and anomalies found at lower levels all drive escalation to more intensive testing.
L1
MANDATORY — EVERY LOT
Visual Inspection, Dimensions, and Weight
Marking examination under magnification (10×–40×) with reference comparison, package surface condition, lead/pin condition and oxidation state, dimensional verification against datasheet, weight measurement versus specification. No specialised equipment required beyond an optical microscope and micrometer. Zero part consumption. Takes 5–15 minutes per sample set. Any anomaly at Level 1 triggers escalation to Level 2 or directly to Level 3 for clearly significant findings.
L2
STANDARD — ELECTRONIC COMPONENTS
X-Ray Imaging and DC Electrical Characterisation
2D X-ray inspection comparing die presence, size, bond wire count, and lead frame design against reference images. DC electrical parameter measurement against datasheet specifications. Non-destructive — applicable to all sampled components before any destructive testing. Standard for any component from independent distributor or broker source. Any anomaly at Level 2 triggers escalation to Level 3.
L3
SUSPECT LOTS OR HIGH-RISK SOURCE
Decapsulation, Chemical Analysis, Full Functional Test
Die exposure via decapsulation and comparison of die markings, dimensions, and circuit topology against reference. XRF lead plating composition analysis. FT-IR package material identification. Full functional electrical testing at rated operating conditions across the temperature range. C-SAM acoustic microscopy if recycled components are suspected. Applied when Level 1 or Level 2 anomalies are found, when the source is a new or unverified broker, or when the component is safety-critical.
L4
HIGHEST RISK / DEFINITIVE AUTHENTICATION
Full DPA, Layer Delayering, Die Reverse Engineering
Full destructive physical analysis (DPA) per AS6171/4 including complete internal documentation. Die layer delayering with SEM imaging of each layer, compared against confirmed genuine die topology. Reserved for: safety-critical components (aerospace, medical, automotive) where absolute authentication is contractually or regulatorily required, extremely high-value components where the cost of authentication is proportionate, or definitive resolution when lower-level tests produce inconclusive results.
Sampling Strategy
Full 100% inspection of every component in a lot is impractical for most organisations and for most test methods. Statistical sampling based on AQL (Acceptance Quality Limit) provides a defensible inspection framework — sampling size is determined by lot size and the acceptable quality level for the application. Standard electronics incoming inspection applies AQL 1.0 for critical components and AQL 2.5 for standard components per ANSI/ASQ Z1.4.
For destructive tests (decapsulation, chemical analysis): increase sample size for higher-value or higher-risk lots, but accept that sampling cannot provide 100% assurance — sampling detects population-level counterfeiting; a few counterfeit units seeded among genuine units in a large lot may escape sampling. Use source control and supplier qualification to reduce the probability that mixed lots enter the supply chain at all.
Internal Capability vs. Third-Party Laboratory
IN-HOUSE
Internal inspection capability
Appropriate for organisations with continuous high-volume inspection needs. Requires capital investment in equipment (X-ray system, optical microscopes, electrical test fixtures) and in-house expertise development. Provides lowest per-test cost at volume, fastest turnaround, and operational flexibility. Most organisations maintain in-house Level 1 and Level 2 capability; Levels 3 and 4 typically remain specialist outsourced capabilities.
3rd-PARTY LAB
Specialist testing laboratory
Appropriate for organisations with infrequent or complex inspection needs, or for Levels 3 and 4 testing beyond in-house capability. AS6081-certified test laboratories provide independent inspection with documented chain of custody — valuable for dispute resolution and regulatory compliance. Higher per-test cost than in-house but no capital investment or expertise maintenance required. Turnaround time: typically 1–3 weeks for comprehensive analysis reports.
⚠ Report confirmed counterfeits to industry databases: When a counterfeit component is confirmed, report the finding to ERAI (Electronic Resellers Association International), GIDEP (Government-Industry Data Exchange Program for defence/aerospace supply chains), or equivalent industry reporting databases. These platforms aggregate counterfeit findings to enable other organisations to identify at-risk part numbers and lot numbers before they enter their own supply chains. The intelligence network is only as effective as the reporting rate — confirmed findings that are not reported do not protect other buyers from the same lot.
Summary
Counterfeit detection requires a layered, escalating strategy — no single technique is sufficient, and each test method reveals a different class of counterfeit. Apply the AS6171 standard framework as the basis for a systematic inspection programme. Visual inspection under magnification with reference comparison is mandatory for every lot. X-ray imaging and DC electrical characterisation are standard for all non-authorised-distributor sourced components. Decapsulation, XRF, FT-IR, and functional testing are applied to suspect lots and safety-critical components. C-SAM acoustic microscopy is particularly effective for identifying board-pulled recycled components that pass other tests. Full die reverse engineering provides definitive authentication where the cost is justified. Scale inspection depth to source risk and component criticality using the four-level framework. Document all findings, quarantine non-conforming lots, and report confirmed counterfeits to industry databases to protect others in the supply chain.