When to use gloves

We manufacture low volume, high reliability assemblies (class 3) that are conformal coated. Up until now we have been cleaning after SMT, then after through hole, then immediately prior to coating with test, formal inspection, etc. between cleaning processes.

The new philosophy is to eliminate cleaning immediately prior to coating and to "keep it clean" through the various processes after "final" through hole cleaning. This implies the use of nitrile gloves for any handling after the "final" cleaning (we currently do not use gloves at all).

The questions are: 1. Is it possible to keep the assemblies clean as they go through their processes assuming the use of gloves? 2. If so, when should gloves be mandated? Only after the final cleaning and how do they know when that is? During bare board handling at SMT? Prior to reflow (consider dexterity for hand placing some larger SMT parts or using tweezers)? After reflow when moving to the cleaner? During hand soldering or rework when you know it is going to be cleaned anyway? 3. Is it better to mandate gloves and the overhead associated with it or just accept the cost of a final cleaning immediately prior to conformal coating? 4. How many cleaning processes do your assemblies go through? 5. Is it practical to keep it clean AND not mandate gloves by simply handling by the edges?

I would be interested in your experience (how do you do it) and any document or standard that addresses this. Thank you.

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