Contractual Yield Indemnification Mechanics in Surface Mount Device Subcontracting
Contractual SMT yield indemnification defines financial remedies for scrap exceeding baseline thresholds by isolating line defects from component defects.
Non-Wetting Attribution
Defect Diagnosis
The systematic identification of the root cause of solder failing to adhere to a printed circuit board pad or a component lead distinguishes assembly errors from material quality issues. Conducting non-wetting attribution determines whether the soldering failure stems from oxidized finishes, contaminated boards, or insufficient process temperature. This analysis is critical for deciding whether the board manufacturer, component supplier, or assembler holds responsibility for the yield loss.
Surface Contamination
Microscopic examination and surface analysis methods like energy-dispersive X-ray spectroscopy identify the presence of unwanted elements on the solderable surfaces. If the analysis reveals organic residues, nickel oxides, or silicone oil on the pads, the fault lies with the board manufacturer’s plating process. Conversely, if the solder paste failed to melt or did not reach the correct activation temperature, the assembler’s reflow oven settings are the primary cause of the non-wetting defect.
These findings help resolve disputes between the parties and direct the engineering team to the correct corrective actions.
Preventive Action
Establishing incoming solderability testing of both components and boards reduces assembly line defects. When a lot fails to wet properly during the test, it is rejected and returned to the supplier before assembly. This prevents costly rework and scrapped assemblies.