Hi Rob,
I must take issue with your statement �By definition, no clean solder can be not-cleaned�.
All no-clean fluxes can be cleaned. Whether or not one cleans no-clean depends on a variety of factors. More than eighty percent of all post reflow flux residues being cleaned today are no-clean. Although that sounds like a strange irony, there is a logical reason.
While many applications do not require cleaning, some do. Many contract assemblers operate a no-clean line and just clean the assemblies that require cleaning due to customer, application, or environmental demands. Rather than running two lines, one no-clean and the other water soluble or RMA, all assemblies are reflowed (or wave or hand soldered) with no-clean pastes. The assemblies that require defluxing are then cleaned.
Exfo� Cleaning is never a waste of time. A no-clean process leaves some degree of ionic residue. That is a fact. Eliminating ionic residues will make your board (and application) no reliable. Cleaning either reduces or eliminates ionic and other forms of contamination. The big question is whether your specific application will be negatively effected by the level of ionic contamination left behind on the board. While is true that many applications are not negatively effected by residual contamination, it is likewise true that all high reliability applications (military, flight, space, medical, etc) require cleaning and not-to-exceed levels of contamination.
I am not suggesting that your boards require cleaning. In fact, they may not. But you need to realize that by not removing the flux, you are leaving ionic residue on the boards. You need to determine if this level of residue can cause a failure. Then, you need to determine the cost of a failure. That will determine the value (or lack thereof) of cleaning.
Michael Konrad Aqueous Technologies www.aqueoustech.com konrad@aqueoustech.com
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