A counterfeit semiconductor is usually bought for a reason that sounds sensible — a price below the market, a part in stock when nobody else has it — and the counterfeit is revealed by clues that are visible before the part ever powers up. The price gap, the packaging inconsistencies, and the electrical data all give the part away, and the receiving inspection that looks for them is the defense. This article frames the price window, walks the packaging and marking clues, covers the electrical cross-checks, names the authenticity tools, and closes with a receiving-inspection standard a team can adopt.
The Price Window: When Cheap Is a Red Flag
The counterfeit is usually introduced through a price advantage, and the price window is the first and simplest screen. A genuine part has a market price set by real manufacturing, test, and distribution costs; a counterfeit is cheaper because it skips those costs.
The price window is the gap between the market price and the offered price. A small discount — the normal negotiation of a legitimate distributor — is within the window and is not a flag by itself. A discount beyond the window — a part offered far below the market, or below what the same part costs everywhere else — is the classic remarking signal, because the only way to sell below the real cost is to have skipped the real cost. The counterfeit verification article and the buyer education article document the price-and-supply red flags, and this article frames them as the receiving screen.
The price window is not a precise number because markets vary, but the direction is stable: a price that breaks the window, a source with no history, and a part in stock when the genuine article is back-ordered are the signals that compound. The price is the first clue, and the packaging and the data follow.
Packaging Clues: Mold, Marking, and Date-Code Consistency
The second screen is the packaging and marking, and the clues are the physical evidence a counterfeit cannot fully fake. The mold, the marking, and the date code each carry a consistency that a remarking operation struggles to reproduce.
The mold is the package’s physical character: the finish, the edge, the lettering style, the lead shape. A genuine part has a consistent mold quality; a remarked or repackaged part shows inconsistencies — a different finish, a rubbed or re-struck marking, a lead that does not match the genuine geometry. The marking is the printed identity: the font, the spacing, the part number, and the logo, which a re-marking operation attempts to reproduce and usually gets subtly wrong. The date code is the consistency test: a lot of parts with wildly varying or impossible date codes, or a date code that does not match the part’s production history, is a strong clue. The counterfeit verification article and the incoming inspection article document the packaging checks, and this article makes them a receiving checkpoint.
The packaging screen works because the counterfeit is made by people who are good at making parts look close and bad at making them look identical. The mold, the marking, and the date code are the details that separate the genuine from the close.
Electrical Cross-Checks: VF, Leakage, and Curve Walk
The packaging screen catches the visual clues, and the electrical cross-check catches the parts that look right and behave wrong. A counterfeit can copy the marking and the mold, but it cannot easily copy the electrical behavior of a genuine die.
The electrical cross-check measures the parameters the design depends on: the forward drop, the reverse leakage, and the breakdown voltage, on a sample from the lot. The screen is more than a pass-fail against the datasheet; it is a curve walk, comparing the shape of the measured curves to the genuine part’s shape. A remarked part may pass the headline number and still deviate from the curve at the operating points — the leak that is higher, the knee that is shifted, the drop that moves with temperature. The incoming inspection article and the datasheet comparison article document the curve comparison, and the diode testing article covers the measurement protocol.
The electrical cross-check is the defense against the good-looking fake: the packaging says “genuine” and the curve says otherwise. A lot that passes the visual screen and fails the curve walk is a counterfeit that the packaging could not fully fake, and the curve is the evidence.
The electrical cross-check also carries the temperature dimension that the packaging screen cannot see. A genuine part holds its leakage and its forward drop within a defined temperature envelope; a remarked or counterfeit die, built from a different process or a recycled part, drifts out of that envelope as it warms. The receiving inspection that reads the curve at both the room temperature and a heated point catches the deviation that the cold bench misses. The diode forward voltage article documents the temperature behavior of the forward drop, and the datasheet comparison article covers the temperature-condition discipline that the curve walk applies.
The same temperature dimension explains why the counterfeit is a field risk, not just a purchasing cost. A part that looks and bench-tests genuine can still fail in the field when it runs hot, because its internal die was never built or tested for the operating temperature. The counterfeit that passes the cold screen and the packaging screen is exactly the part most likely to fail in the mission, which is why the receiving standard’s electrical stage is not optional – it is the screen that catches the part whose real behavior does not match its label.
Authenticity Tools and Where to Confirm
Beyond the bench, the authenticity tools and the confirmation sources close the loop, and the tools give the receiving team the authority to reject a lot with evidence.
The tools include the manufacturer’s own verification channels — the authentic datasheet, the part-number cross-reference, and, where available, the manufacturer’s authentication or traceability service. The milliscope and microscopy tools examine the package and the die at the level the naked eye cannot, revealing the internal structure that separates a genuine die from a fake. The confirmation sources are the manufacturer’s official documentation and the qualified-distributor records, against which the suspect lot is compared. The counterfeit verification article and the audit article document the authenticity and traceability sources, and the power discrete package testing article covers the microscopy and internal inspection.
The tools give the screen its authority: a receiving team that can point to the manufacturer’s documentation and the internal inspection has evidence, not an accusation. The tools are what turn a suspicion into a rejection with a paper trail.
The receiving standard is best shown as the table the team runs per lot:
| Stage | Check performed | Pass / fail | Disposition on fail |
|---|---|---|---|
| 1 Price and supply | Price window, source history | Normal price, known source | Flag and verify |
| 2 Packaging | Mold, marking, date-code consistency | Consistent with genuine | Reject with evidence |
| 3 Electrical cross-check | VF, leakage, breakdown, curve walk | Curves match genuine | Reject and quarantine |
| 4 Authenticity | Manufacturer docs, traceability | Confirmed genuine | Reject and report |
| 5 Disposition | Evidence recorded | Accepted or rejected | Record and report |
The table is the standard in one view: each stage names the check, the pass criterion, and the disposition on failure, which is exactly the sequence the team runs on every incoming lot. The counterfeit verification article and the incoming inspection article provide the underlying methods each stage’s pass criterion draws on.
Building a Receiving-Inspection Standard for Counterfeit Checks
The article closes with the receiving-inspection standard, and the standard is the deliverable that turns the clues into a repeatable process. A team without a standard checks parts by mood; a team with a standard checks them by a defined sequence.
The standard has five stages. First, the price and supply screen: flag any lot whose price breaks the window or whose source has no history. Second, the packaging inspection: check the mold, the marking, and the date-code consistency against the genuine reference. Third, the electrical cross-check: measure the VF, leakage, and breakdown on a sample, and walk the curves against the genuine. Fourth, the authenticity confirmation: use the manufacturer’s documentation and the traceability tools to confirm the lot. Fifth, the disposition: reject the lot with the evidence recorded, quarantine it, and report it. The counterfeit verification article and the incoming inspection article provide the underlying methods, and this article turns them into the standard.
The receiving standard is the durable output of the article: the five stages, run on every incoming lot of power parts, are the defense that keeps the counterfeit off the board. The standard, the tools, and the evidence are what make the screen more than a hope.
The counterfeit is bought for a price and revealed by the clues. The price window flags the too-good discount; the packaging and marking catch the physical inconsistencies; the electrical cross-check catches the good-looking fake; the authenticity tools give the screen authority; and the receiving standard makes the whole process repeatable. A team that runs the five-stage standard on every lot has spent the receiving inspection where it matters, and the counterfeit never makes it to the board. The general rectifier category and the sourcing strategy article complete the sourcing and verification picture.