Doug Yes and I can! Bergendahl, C.G. and Dunn, B.D. Evaluation of Test Equipment for the Detection of Contamination on Electronic Circuits, European Space Agency Technical Memorandum ESA-STM-234, Paris (1984) Brian [log in to unmask] wrote: > > Brian, > Was the ESTEC study you refer to ever published? If so, can you provide > the reference? > > Doug Pauls > > > *Brian Ellis <[log in to unmask]>* > Sent by: TechNet <[log in to unmask]> > > 08/25/2009 01:17 AM > Please respond to > TechNet E-Mail Forum <[log in to unmask]>; Please respond to > Brian Ellis <[log in to unmask]> > > > > To > [log in to unmask] > cc > > Subject > Re: [TN] ROSE Equivalency Factors > > > > > > > > > I agree with Doug. The European Space Agency (ESTEC) did a profound > study with 4 different makes of tester and (I think) 6 different types > of flux, cleaned according to manufacturers' recommendations and found > there was absolutely zero correlation between them. It was impossible to > determine a so-called equivalency factor (aka as fiddle factor or fudge > factor) for any given instrument, as it varied greatly with different > fluxes and different cleaning processes. The whole notion was dreamt up > by NAFI in a nightmare; their testing was unscientific as they > determined it for instruments very different for those used today with > uncleaned boards, using a reference method that is, in itself, > unscientific and imprecise. > > Forget the whole notion of equivalence because none exists and the > figures were, in any case, determined for instruments that were marketed > a quarter of a century ago and whose only resemblance to todays' ones is > that they may bear the same name. The ONLY way of using ionic > contamination testers is, during qualification, to determine the mean > and the standard deviation of the residual contamination on assemblies > deemed safe for the intended purpose, individually for each type of > board you make, using YOUR instrument under standardised conditions. > During manufacture, the mean should fit within the Gaussian curve > determined during qualification. If it deviates in either direction, > then you know that your process has changed somewhere along the line > between goods-in and cleaning. > > If you have a certain book, Chapter 20 explains the danger of using > equivalence factors and the use of mean/standard deviation for > determining SAFE process control. > > Brian > > Richard Kraszewski wrote: > > Can someone please refresh my memory and tell me which document has the > > equivalency factors for the various ROSE testers? I seem to think that > > it was the IPC TR 583, but I don't see them there. Believe it may have > > been a Military document. > > > > Thanks > > > > Rich Kraszewski > > > > > > --------------------------------------------------- > > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > > 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 or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > > Search the archives of previous posts at: > http://listserv.ipc.org/archives > > Please visit IPC web site > http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 > ext.2815 > > ----------------------------------------------------- > > > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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 or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site > http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 > ext.2815 > ----------------------------------------------------- > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------