As I suspected, Mil-P-55110 is inactive and the latest revision was MIL-PRF-55110F(1) dated November 1998. It was replaced by MIL-PRF-31032/4 which is active. Again, this is a spec covering the product and not the supplier. A glance through does not reveal the acceptability or otherwise of so-called "white residues". I would be suspicious of any company stating they are a 55110-qualified board manufacturer: a) they are not with it and b) the spec covers only the products. Do they mean that their products may be made to conform to the spec, on request? Brian > Bogert wrote: > > 3/30/002 > > Folks, we have an OEM who purchased FR-4 printed wiring boards from a > MIL-P-55110 qualified board manufacturer. The OEM wave soldered > the PWAs using HF1189A water washable, organic flux and cleaned the > assemblies using DI water in an in-line cleaning process. Subsequent > Omegameter 600 ionic cleanliness testing passed. However, almost all > of the solder side of the PWAs exhibited white residue. Basically it > looks like a water mark. While you can remove the residue > using abrasion, such as by a pencil erasure, it comes back, even after > several subsequent baking operatioins and additional in-line > cleaning. The OEM sent out samples for outside chemical evaluation > and found minute traces of carbon. The OEM traced the problem to > incomplete curing of the LPI solder mask. The white residue only > appears on the solder side of the PWA. There is no evidence of the > residue on the component side of the assembly. > > The OEM proposes that a sample assembly be sent out for SIR testing, > and that if the test passes, they will request us to accept the > condition as is. My concern is that over time in a humid environment, > we may experience leakage current paths that cound cause operasting > failures. The OEM has 20 PWAs that are part of the lot. However, > only 6 experience this condition. It appears that I should reject all > PWAs that show evidence of the white residue. I am concerned with the > presence of carbon, even in trace amounts. The OEM noted that almost > everything will show traces of carbon, so not to worry. > > Bottom line is, is there any technical concern if the white residue is > present? Any input on this topic wo\uld be appreciated. --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------