Clarify what is being tested
In a PCB assembly project, burn-in usually refers to operating populated electronics for a defined period under specified conditions as part of a screening plan. A bare PCB electrical test checks a different object and does not substitute for operating the assembled circuit.
The term is also used in semiconductor testing, where a burn-in board can be a fixture that carries devices under test. State whether your inquiry concerns an assembled product, individual components or the fixture used to test them. ESPEC’s inspection equipment overview shows examples of equipment for these different testing tasks.
Start with the purpose and limits
Describe the faults the screening is intended to reveal and how the results will affect release. Define the product revision, operating modes, electrical loads, ambient conditions and permitted limits. The product and component requirements should govern the plan.
Burn-in, environmental qualification, thermal cycling and accelerated stress methods are not interchangeable labels. Avoid specifying a generic temperature and number of hours without an engineering basis. The test needs to exercise the relevant functions without introducing uncontrolled damage.
Make the test repeatable
- Assembly revision, firmware and unit or lot identification.
- Fixture, power supplies, loads, connections and software revisions.
- Conditions, duration, operating sequence and measurement intervals.
- Monitored quantities, pass/fail limits and automatic protection where required.
- Handling of interruptions, failures, retests and repaired units.
Check that the fixture and chamber loading allow the intended conditions at the assemblies. Distinguish a chamber setpoint from the temperature at a component or board location when that difference matters to the plan.
Use the results as evidence
Keep the results tied to the units tested. A useful record includes the procedure revision, conditions achieved, exceptions and disposition of failures. Investigate patterns rather than simply replacing failed units and counting the survivors.
Passing the screen demonstrates compliance with that screening procedure; it is not a general guarantee of field life. When requesting a quotation, provide the approved procedure or identify who will develop and approve it, along with the quantity and required reports.