First of all many thanks for feedback on OSP and Immersion gold as finish -HASL Alternatives. I am looking for info on another problem. The description is as follow: We are using HASl finish on a board using 15.7 mils and 0603 components. (That is why I asked opinion on Finish earlier). The board is having all the untested vias solder masked on pads. In recent lots from One board vendor, our inspectors have observed black residue or coloration on a portion of via . Some of the masked vias are having black residue.It appears to be molten mask -turned black from its original green color. Some other places, the greenish tinge is reduced in intensity and thiose are places where it is affected to lesser degree. If we probe or smear gently the blackish portion, the mask comes off (peel off) very easily exposing the copper.The material is tacky, paste like . Anybody there who can help us what it could be. The board manufacturer is saying that the residue is non-ionic . My question is: - Anybody came across this / similar problem ?Is it common problem with masked vias with hole open ?The solder pad is 25 mils and hole is 12 mils ( 1 mil = one thousandth of an inch). - the concern for reliability is valid or not --even if the black residue --flux or solder mask or any contamination --is passing the ionic test.Do you have any suggestions on other tests which we can suggest board vendor to carry out ? e.g. SEM ?? Please post your replies on IPC Technet . thanks ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################