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A test vehicle and qualification test for proving out process changes.

IPC J-STDF-001G states, “Unless otherwise specified by the User, the Manufacturer shall [N1D2D3] qualify soldering and/or cleaning processes that result in acceptable levels of flux and other residues.  Objective evidence shall [N1D2D3] be available for review.”1 (Ed.: N1D2D3 means no requirement has been established for Class 1, and the condition is a defect in Classes 2 and 3.)

In a qualified manufacturing process (QMP), manufacturing materials and processes used to produce electronics hardware are benchmarked and validated against electrical performance in hot/humid conditions.2 Characterizing chemical residues that exist on a manufactured assembly, and assessing the impact of those residues on electrical performance, has much to do with the end-use environment in which the hardware will operate. The other important factor is the circuit density and component types. Leadless and bottom-terminated components are more susceptible to residue challenges due to low standoff gaps, tight pitch, high solder mass, and blocked outgassing channels.

Here, we assess the impact of process residues on electrical performance to qualify electronics hardware and the manufacturing process. The qualification methodology will determine the acceptability of the residue condition at the point of the manufacturing process just prior to the application of conformal coating.

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