Electronics Forum | Thu Oct 17 23:25:53 EDT 2002 | redmary
We generally etch the copper back slightly using a 50/50 mix of 3% Hydrogen Peroxide and laboratory grade Ammonium Hydroxide. Swab for about 5 seconds, then rinse. and etch the tin in the solder to further delineate the intermetallic layer that shou
Electronics Forum | Fri Sep 12 09:10:23 EDT 2003 | Norm Morikawa
Around 1989 I had this probelmm with a SMT CCA that would not solder in one area consistently. I had it cross sectioned by the bare board supplier and found that under their metallurgical microscope the thickness of this HASL bare board could not be
Electronics Forum | Fri Feb 11 01:36:22 EST 2005 | brown
OK I am counting someone knowing this. True or False, if my touch-up operators touch-up the smt solder joints too many times will this make the joint weaker? if yes why? and what happens to my intermetalic layer? I have insisted if it looks good don
Electronics Forum | Thu Oct 20 23:01:12 EDT 2005 | davef
A highly activated flux will allow intermetallics to form, because the hydrogen halide gas that formes at operating temperature will react with the refractory nickel oxide. Refractory nickel oxide is what makes SS "stainless". This will be worse wit
Electronics Forum | Fri Nov 25 12:12:46 EST 2005 | pjc
To state whether an oven can or cannot "do lead free" very much depends on what type of product you need to solder. High thermal mass products are problems for 4 and 5 zones ovens becauase they typically cannot follow the solderpaste mfrs. profile, u
Electronics Forum | Fri May 12 12:07:10 EDT 2006 | solderiron
The kester better known as KY'd Sn/Cu has more copper intermetallic growth over time, dissolves copper from the board faster so repairing and touchup can damage board. Bridges more than SN100c. Does not thermal cycle well. Has shrink cracks that can
Electronics Forum | Tue Jul 18 21:48:15 EDT 2006 | davef
We assume by "solder hole" you mean void. We believe void formation is driven by the thermal recipe that you've chosen to use. Search the fine SMTnet Archives for further discussion. There is a tremendous amount of current industry discussion on v
Electronics Forum | Wed Dec 20 16:30:40 EST 2006 | CK the Flip
I've seen smaller components have a "charred" appearance and a lack of wetting up the component termination. Also, extended heat exposure may introduce excessive IMC (intermetallic) formation - the bad kind, that is. That's where your IMC layer wil
Electronics Forum | Thu Apr 12 17:34:05 EDT 2007 | carsan
We are running RoHS compliant & non RoHS compliant assemblies. We buy our bare boards from one supplier that only manufactures RoHS compliant boards using a Sn100 finish. Is there any known issues running leaded solder on a Tin finish? Does normal
Electronics Forum | Thu May 10 08:09:52 EDT 2007 | davef
There is no standard for time above liquidus. It is described rather broadly by the solder paste supplier. Reflow Zone: If the temperature is too high, boards may char or burn. If the temperature is too low, cold and grainy solder joints will resul
