I�m aware of no such standard. There may be something in Euroland [ie, IEC, etc.]
TM-650 �Test Methods Manual� has procedures for measuring various types of contamination, such as: * 2.2.25 �Detection Of Ionizable Surface Contaminants� * 2.2.27 �Cleanliness Test � Residual Resin� * 2.2.28 �Ionic Analysis Of Circuit Boards, Ion Chromatography Method� * 2.2.38 �Surface Organic Contamination Test� * 126.96.36.199 �Surface Insulation Resistance, Fluxes�
The level of these contaminants SB such that the do not compromise the product performance, er words to that effect. Various test labs; such as CSL, Trace, Robisan; help their customers develop guidelines for allowable levels of various contaminants, based on the end-product use, type of test, the manufacturer of the test equipment, and whatnot.
Points to consider: * �Dull� appearance alone is not an indicator of solder connection quality. Dewetting certainly is. Taken together, they indicate something nasty is going on with your assembly. * Some alternate solderability protection materials: - Appear different from SnPb lead solderability protection. - Require soldering profiles different from SnPb solderability protection. [For instance, TI�s site has information of their Pd solderability protection. http://www.ti.com/sc/docs/asl/palladm/index.htm] * Some combinations of board and component lead solderability protection require profile adjustments.
Questions are: * If the component is the problem, why did the board dewet, rather than the component? * What is the coating of the component of concern? Who is the supplier? What does the supplier say about the appearance of the lead solderability protection? * What is the solderability protection of the bare board of concern? * What is the temperature profile taken on the dewetted lead? * What is this component? * What is your process prior to noticing the problem?