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 | Wed May 03 22:14:29 EDT 2006 | davef
We think well done carbon ink and well done ENIG are equally reliable [maybe 1M operations]. If the gold is pourous [not all that an uncommon], ENIG is far less reliable than carbon ink.
Electronics Forum | Thu Dec 14 12:18:01 EST 2000 | genny
Hello all, Our company has always used HASL finish on our products. Recently however, we have a had a problem on a couple of boards that I have been told cannot be avoided with HASL, and we should switch to ENIG(electroless nickel immersion gold).
Electronics Forum | Fri Dec 15 13:57:46 EST 2000 | genny
It is only after the reflow heating process that the peaks may show up, as the solder build up in some vias(due to HASL'ing) might drip down during reflow. I don't think I've ever heard of it being desirable to have a bare copper surface that will ox
Electronics Forum | Sat Nov 03 11:08:24 EDT 2012 | anvil1021
We have experience with this alloy, but with enig and we did start with PB HASL, none of our PCBs would of course pass thermal cycling at normal temperatures with the HASL so we went to ENIG. we could thermal cycle at 100-115C with no issues. We foun
Electronics Forum | Wed Jan 24 10:08:36 EST 2007 | electronhose
Immersion Silver, ImAg, is becoming the finish of preference. This is due to it having similar process limits vs. SnPb HASL. There were some early concerns about shelf life, but new chemistries have extended finish shelf life to 12 months+. Many boar
Electronics Forum | Thu Dec 14 19:38:28 EST 2000 | Dave F
OK, now let me ask the really dopey question ... so if the irregularity of the HASL surface is punching holes in the thermal gasket and causing shorts to the heat sink, why are you putting solder on that surface? I wonder how the thermal conductivit
Electronics Forum | Mon Jul 26 09:19:57 EDT 2004 | davef
Both imm silver and ENIG provide flat surfaces that are better for fine pitch placement and reflow than HASL. We know of nothing that makes BGA locations different than other locations when using ENIG solderability protection. More broadly, the pri
Electronics Forum | Sat Dec 22 01:34:26 EST 2018 | sara_pcb
My BGA is 0.5mm pitch with Sn66Pb36Ag2 ball. My PCB finish is HASL. Want to do reflow using Eutectic Sn-Pb reflow paste. My Assembly is IPC Class 3 product. 1. Is there any long term reliability issues with 2% Ag in BGA Ball. 2. If the PCB finish
Electronics Forum | Sat Jul 28 08:37:52 EDT 2007 | davef
There is no good choice. Board Finishes: Industrial/Battelle Class 3 Environment [Reliability Knowledge Gaps: For use of Pb-free solders in High Reliability Applications, J Smetana, iNEMI Availability of SnPb-Compatible BGAs Workshop, March 1, 2007,
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