Electronics Forum | Thu Mar 30 08:59:46 EST 2006 | Dan
Yes the balls are at the outer edge. The chips we have are not showing exposed copper, but the lead-free finish...
Electronics Forum | Tue Jul 07 08:42:49 EDT 2009 | ewchong
kpm, you are probably right. under magnification those two pads show some exposed copper which means that they were contaminated or had insufficient solder paste before reflow.
Electronics Forum | Wed Jan 26 14:33:14 EST 2011 | remullis
Exposed copper on the edges of boards is what I'm refering to. could be a potential shorting issue in your housings. Just depends on the application. We have cut into ours and use humiseal to dress them off. Rich
Electronics Forum | Sun Feb 23 21:19:08 EST 2020 | sssamw
Yes, this is for tin-lead profile. And for the QFN pins which has copper exposed that not required and not possible to have fillet on side surface as in IPC, see 8.3.13, in IPC-A-610-G
Electronics Forum | Mon Jul 11 19:32:27 EDT 2005 | fctassembly
Yes, there have been many issues with the fast dissolution of copper by the SAC305 alloy. In fact, there are companies who have disqualified it for repair operations due to loss/thinning of the pads. SN100C dissolves copper much slower than SAC305 an
Electronics Forum | Mon May 14 17:12:20 EDT 2001 | davef
Continuing along the path that Brian took ... IPC-7525 gives design guideline for stepped stencils. It goes something like: * Stepped area SB GT 25 thou from pads located on the greatest thickness of the stencil * Pads in stepped area SB GT 35 tho
Electronics Forum | Fri Jan 06 11:29:28 EST 2006 | mdemos1
Hi. I was curious what some common accept/reject criteria would be on copper wall thickness. For instance, if 1 ounce copper is used, I believe the IPC specification is 0.001" minimum thickness. Should the order be rejected if there is one measure
Electronics Forum | Thu Jan 08 14:33:50 EST 2004 | dwzeek
Toe fillets are not required per IPC. Toe fillets could be used as a process indicator, if you desire; I would not. Gull wing leads are typically cut off on the ends when manufactured; this exposes the non-plated material in the lead, typically coppe
Electronics Forum | Wed Dec 05 18:28:54 EST 2012 | cnotebaert
what type of part is this a micro BGA by chance? there is a mill spec (man I cant remember it right now), I'll get back to you! it provides acceptance criteria for chip/crack/gouges.... if it doesn’t expose the lead frame (inner workings of the devic
Electronics Forum | Wed May 24 11:21:32 EDT 2000 | Travis Slaughter
Its my understanding that so long as the paste is not exposed to air it is not going to be active, someone else might be more sure about this than I am. Be ready for lots of half soldered leads using this process. Its quick and easy but will not b
