OrCAD X Resources

When Your Component Is Unavailable: Alternates, Last Buys, and Counterfeits 4 www.cadence.com The following stages apply to medium and high-risk alternate qualifications. Stage Actions and acceptance criteria 1. Datasheet comparison Compare all parametric values against primary source. Flag any deviations. Assess whether deviations affect the specific circuit application. Do not approve if critical parameters diverge. 2. Physical verification Obtain samples. Verify physical dimensions against footprint. Check lead finish, marking, and date code. Verify package dimensions against manufacturer datasheet. 3. Assembly sample Assemble a small batch using the production assembly process and solder profile. Inspect solder joints using AOI and cross-section one joint per package type. Verify solder joint geometry is within IPC-610 acceptance criteria. 4. Functional testing Test assembled boards across the full functional test suite. For analog or RF circuits, include parametric measurements at the boundary conditions of the design specification, not just at nominal conditions. 5. Environmental stress For production-intent alternates, subject assembled boards to thermal cycling and any other environmental tests that apply to the product. Duration and stress levels should be proportional to the application and industry requirements. 6. Documentation Document the qualification results in a format that can be used to update the component database and BOM. Include the test conditions, sample size, results, and the specific lot of parts tested. Note any conditions or restrictions on the approved alternate. 1.3 PCN Response and the Requalification Decision A Product Change Notification (PCN) is not an End-of-Life notice. A PCN signals a manufacturer change to a component that is still in production: a process change, raw material substitution, package revision, die shrink, or factory relocation. Unlike an EOL event, a PCN does not immediately threaten availability. The question it raises is different: does this change affect how the component behaves in your specific application, and does it require requalification? Most engineers treat PCN response reactively. A notification arrives, they review it, and they make a judgment call on whether to act. The problem with that approach is that the judgment call is made without a consistent framework, which means similar changes get different responses depending on who receives the notification and how much pressure the team is under at the time. PCN categories and their default response Not all PCNs require engineering action. The appropriate response depends on what changed and how critical the component is in the application: PCN type Default response Factory relocation, no specification change Documentation review only. Verify the new site is the same manufacturer entity and update the approved supplier list if required. No sample testing required unless the application is life-safety-critical. Raw material substitution within specification Review the specific materials changed. For passive components, verify the substituted material does not affect temperature coefficient, aging characteristics, or dielectric properties. Request updated material declarations for compliance records. Package revision with same footprint and pin-out Physical verification. Obtain samples and verify the revised package against the footprint in use. Check for changes to thermal pad size, lead finish, coplanarity specification, or moisture sensitivity level. Die shrink or process node change Functional requalification required. A die shrink within the same product family stays within datasheet limits by definition, but analog behavior, noise characteristics, and leakage current can change measurably. Test at application boundary conditions, not just nominal conditions.

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