Electronics Forum | Tue Jul 15 16:30:57 EDT 2008 | boardhouse
Hi Aj, Recommended Immersion gold thickness would be 3-5 Micro inches over 140 -200 micro inches of Nickel. Thicker Immersion gold than 5 micro inches can cause solder joint embrittlement. Gold readily dissolves in molten solder and will be present
Electronics Forum | Wed Nov 17 10:03:29 EST 2010 | scottp
Instead of a minimum thickness, we require no exposed copper or SnCu intermetallic. We've been having a lot of trouble lately with suppliers of SN100 HASL boards giving us pads with very irregular solder deposits with areas of exposed intermetallic.
Electronics Forum | Mon May 18 13:18:25 EDT 1998 | Chrys
I'm reviewing my board fab spec. It calls for a minimum SnPb thickness of 50 microinches on HASL PWB's. I've looked at other specs that call out anything from 30 to 80 microinches, and others that just say the copper pad must be covered and soldera
Electronics Forum | Tue Sep 09 18:07:18 EDT 2003 | davef
We would be very wary of allowing 50 uinches, because this will likely result in reduced shelf life due to intermetallic growth. As a guesstimate, at least 10 uinches of that 50 uinches, and maybe more, is already intermetallic when you receive the b
Electronics Forum | Wed Sep 10 12:56:09 EDT 2003 | davef
Intermetallic compounds [IMC]: * Form during the alloying process of some metals. In soldering these are Sn, Ni, Ag, Cu, Au. * Do not accept solder. * Increase in depth in logarithmic proportion to both time and temperature. [So during the solder
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 | Mon Feb 19 18:57:49 EST 2001 | davef
Expanding on the limit of the portion of gold acceptable in a solder connection [mentioned in an earlier post]: The embrittlement culprit, AuSn4, is 29 weight percent gold. So even if one had 100% tin as the solder alloy and 10% gold were dissolved
Electronics Forum | Thu Feb 15 19:41:38 EST 2001 | davef
What do you mean by "But after performing temperature cycle test, the former aging rate (from the shear strength ) seems faster than the latter."? Comments are: I can't recall having heard the term "precipitation hardness" [not that that means anyt
Electronics Forum | Tue Feb 20 16:31:49 EST 2001 | davef
Let�s be basic. The two most common causes of BGA opens that we talk about here are: 1 Gold thickness and 2 Black pad. Given the thickness of gold that you talking about, it�s reasonable to consider thickness as the first alternative to investigat
Electronics Forum | Mon May 18 13:30:15 EDT 1998 | Earl Moon
| I'm reviewing my board fab spec. It calls for a minimum SnPb thickness of 50 microinches on HASL PWB's. I've looked at other specs that call out anything from 30 to 80 microinches, and others that just say the copper pad must be covered and solde
