Packaging Failure Analysis — When Something Goes Wrong, How Do You Find the Root Cause?

I. The Standard Failure-Analysis Workflow

Even a perfect process can occasionally go wrong — failure analysis (FA) is the “forensic examiner” of the packaging world, reconstructing the truth from the wreckage. The standard workflow has four steps:

Step 1: Failure confirmation and preservation— first reproduce the failure, then photograph and archive the failed unit; blind disassembly that destroys evidence is strictly forbidden.

Step 2: Non-destructive inspection— external microscope examination and X-ray views of the interior (broken bond wires, solder voids, and die cracks cannot hide), plus hermeticity retesting to locate leaks.

Step 3: Decapsulation analysis— open the lid mechanically or by laser and inspect the interior under the microscope: bond lift-off? Burned die? Metal migration?

Step 4: Root-cause localization— combine electrical tests, morphology, and process records to pin the failure on a specific process step and parameter.

II. Three Typical Cases: Different Symptoms, the Same Method

Case 1: a customer complained of falling optical-module output power. X-ray inspection found a neck fracture in a bond wire — the root cause was overly aggressive bonding parameters; the damaged neck later failed by fatigue.

Case 2: a batch failed hermeticity testing. Decapsulation revealed microcracks in the sealing glass — the cause traced back to an out-of-spec cooling rate; thermal stress cracked the glass.

Case 3: insulation resistance dropped after high-temperature storage. Analysis showed plating pinholes letting corrosion products bridge the pins — the root cause was drift in the electroplating process parameters.

All three cases point to the same conclusion: the value of failure analysis lies not in inspecting failed parts but in feeding the root cause back into the manufacturing process — which is exactly why Xuri’s quality system relies on closed-loop failure management and keeps every problem traceable.

[Series Complete] This series — from die attach and bonding, temperature-control design, and optical windows to package selection, thermal management, and failure analysis — together with the previous series on fundamental principles and process knowledge, has now covered the full chain of hermetic packaging from beginner level to practice.

[Glossary]

1. Failure Analysis: the systematic technical activity of determining failure modes and locating root causes

2. X-Ray Inspection: a non-destructive inspection method that uses X-rays to see the internal structure of a package

3. Decapsulation: an analysis technique that opens the package housing to inspect internal structures

4. Closed-loop Management: a quality-management method that feeds failure root causes back into the manufacturing process and verifies the improvement