Bond and interface failures
Failures at the cladding interface. Most critical — usually means the supplier used electroplating or weak cladding.
| Failure mode | Detection | Root cause | Prevention |
|---|---|---|---|
| Delamination during bending | 90° bend test, visual | Electroplating instead of cladding | Specify metallurgical cladding in RFQ |
| Peel strength < spec | Peel test per ASTM B566 | Insufficient cladding ratio or weak bond | Audit cladding process, require ≥60 MPa |
| Interface voids | Cross-section microscope | Dirty raw material or poor cleaning | Verify cleaning step in process audit |
| Resistance rise after TC | Thermal cycling + resistance | Diffusion barrier failure | Request diffusion barrier alloy if needed |
Mechanical failures
Failures during stamping, bending, winding, or vibration. Often related to temper or edge condition.
| Failure mode | Detection | Root cause | Prevention |
|---|---|---|---|
| Cracking at bend radius | Bend test per application | Temper too hard | Specify softer temper or annealed condition |
| Burr formation in stamping | Visual + micrometer | Slitting tool wear or wrong edge | Specify edge condition, audit tooling |
| Springback in forming | Dimensional check post-form | Yield strength too high | Specify yield strength range, not just temper |
| Fatigue in vibration | Vibration test per ISO 16750 | Surface defects or inclusions | Request surface inspection report |
Electrical and surface failures
Failures in conductivity, solderability, contact resistance. Often related to coating or surface contamination.
| Failure mode | Detection | Root cause | Prevention |
|---|---|---|---|
| Conductivity below spec | Resistance bridge | Cladding ratio below spec | Verify % IACS on every lot cert |
| Poor solderability | Wetting balance test | Coating oxidized or too thin | Specify coating thickness + shelf life |
| Contact resistance high | mΩ meter at connection | Surface contamination or oxide | Request cleaning + protective packaging |
| Corrosion in damp heat | DH1000 visual + resistance | Cladding too thin at edges | Specify min cladding at narrowest point |
PV ribbon specific failures
Failures specific to PV ribbon in module manufacturing. These cause stringer downtime and module reliability issues.
| Failure mode | Detection | Root cause | Prevention |
|---|---|---|---|
| Stringer feeding instability | Stringer yield log | Camber or spool tension out of spec | Specify camber ≤1 mm/m, audit winding |
| Cell cracks after soldering | EL imaging | Ribbon yield strength too high | Specify yield strength ≤80 MPa for thin cells |
| Low peel strength | Peel test per IEC 61215 | Coating wrong alloy or low temp | Match coating to stringer temperature |
| Hot spot in module | IR thermography | Resistance variation across ribbon | Specify resistance Cpk ≥1.33 |