What is the cleanliness criterion for flux residues as per IPC-A-610?

The cleanliness criterion for flux residues as per IPC-A-610 states that residues must not exceed specified levels. This is crucial because flux residues can potentially impact the reliability and performance of electronic assemblies if left unchecked. The IPC-A-610 standard acknowledges that although some flux residues may be allowable, they must adhere to clearly defined limits to ensure they do not interfere with the electrical, mechanical, or thermal performance of the assembly. By establishing specified levels, the standard helps manufacturers maintain quality control and protect the longevity of the products they produce. Cleanliness is not solely about having no residues at all, but rather managing their presence to ensure that they remain within tolerable limits for the assembly's effectiveness.