Summary of No-Clean
Technology Review

The major findings of this review include:

• No-clean fluxes have been proven to be a technical viable alternative to fluxes that require post-solder cleaning for both wave and oven reflow soldering. Performance of electrical assemblies manufactured with no-clean fluxes have been shown to meet the specifications of many manufacturers.

• Many no-clean fluxes leave behind a visible residue that, while not impeding performance, does affect visual cosmetics. Manufacturers and customers must be willing to relax visual criteria if they are going to use many of the no-clean fluxes available on their products.

• Using a no-clean flux does not necessarily eliminate all cleaning in the solder area. The screen printing equipment and any mis-screened boards still require cleaning. It is also possible to use spot-cleaning after soldering for aesthetic reasons.

• Use of an inert atmosphere, such as nitrogen or, in some special cases, a reactive hydrogen atmosphere, can improve the no-clean soldering process by reducing residue and, in some cases, decreasing certain types of defects.

• At this time, implementation of no-clean soldering requires a significant effort on the part of the manufacturer to conduct tests and product trials. This requirement should lessen over time as the technology becomes better understood, making no-clean soldering more widely available to smaller electronics manufacturers that do not have research budgets.

• It is typically very economical to convert from cleaning-based soldering to no-clean soldering since the entire post-solder cleaning process can be eliminated, and it is often possible to use the no-clean flux with existing flux application and wave or oven reflow soldering equipment. However, there are potential increased costs due to increased inspection of incoming components and the need for increased process control.

• More detailed cost assessments of converting to no-clean fluxes would be useful to manufacturers, researchers, and technical assistance providers working on no-clean conversions.

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