Steve, When you OSP coat your board fiducials is there anything special you have to do for your Pick & Place (Zevatech) machine to see it? Thanks in advance, Kathy Palumbo Viking Components > ---------- > From: Stephen R. Gregory[SMTP:[log in to unmask]] > Sent: Friday, February 20, 1998 1:24 PM > To: [log in to unmask] > Subject: Re: [TN] gold over entire board > > I'd like to add to David's comments too...I tend to agree with him on > his > point about OSP's. In order of preference, the board finishes I'd > `druther see > on SMT boards that I'd have to build are 1. OSP, 2. Flash Gold, and 3. > HASL. > > A few more good things that I've observed with OSP's in addition to > what David > said are; 1. Less solder bridges on fine pitch - The solder seems to > stay > right where it's printed during reflow on a OSP coated board...it's > like the > flux has to use some of it's activity to go through the OSP before it > reaches > the pad surface and does it's thing, and all that is confined to the > area > where the paste actually is. It's almost like the OSP coating that's > in > between the pads acts like a little "dam" if you will, preventing the > molten > solder from easily crossing over to an adjacent pad. 2. No heat used > applying > OSP's - Less board warping... > > There's a couple of caveats with the board houses that say they > can do > OSP's. I've run across a few that say they do OSP's, because it's easy > to say > that. Only because one can go out and buy gallons of the chemical, > pour it in > some sort of tank to dip the boards in, and voila'...you're doing OSP > board > finishes. But that's really not the best way to apply the coating. The > thickness of the coating needs to be controlled. It may not be a big > deal if > you're in a water soluble process and use flux so active that you can > solder > to dirt, but when you're using a no-clean / low activity flux, you'll > have a > hard time soldering if the coating is too thick. > > One more board house problem I've run across is that they've done the > bed-of- > nails testing (or bare board test) after they've applied the > coating...that's > a no-no. The probes will break thru the coating and compromise it's > integrity. > OSP's are meant to be applied and stay in an unbroken layer until it's > ready > to be soldered, that's how it protects the copper from the oxidizing. > > -Steve > Gregory- > > ################################################################ > 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 web site (http://jefry.ipc.org/forum.htm) for > additional information. > For the technical support contact Dmitriy Sklyar at [log in to unmask] or > 847-509-9700 ext.311 > ################################################################ > ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################