Hi Bob - the primary disadvantage for HASL is flatness and secondary is long term solderability. For automated SMT reflow, the immersion finishes ((ImAg, ImSn, ENIG) have a flatness advantage that is good for fine pitch BGA, flip chip and small resistor/capacitor (0402s, 0201s, 01005s, etc.) assembly. And some HASL are better than others so there have been long term solderabilty issues documented. Again, both tin/lead or lead-free HASL are not bad finishes, they have applications where they work great and other applications not so great. Dave On Tue, Jan 23, 2018 at 9:48 AM, rkondner <[log in to unmask]> wrote: > Bev and John, > > Thank you. So that is two votes for flatness issues. > > Any others? > > Thanks, > Bob > > > On 1/23/2018 10:27 AM, John Burke wrote: > >> >> >> >> >> I believe this is referring to “random highs” where most >> of the pads are relatively flat but on some the solder is still on the pad >> typically high in the direction of the air knife >> >> >> >> Sent from my iPad Pro >> >> >> >> >> >> On Tue, Jan 23, 2018 at 7:18 AM -0800, "BEV CHRISTIAN" < >> [log in to unmask]> wrote: >> >> >> >> >> >> >> >> >> >> >> Bob, >> Please explain what in your case you mean by “warts”. Did you mean that >> literally or as you using the term as Wayne was? HASL is by its nature is >> not flat. >> >> I would contend that HASL flatness CAN be an issue that solder paste is >> not always going to fix. >> >> Regards, >> Bev >> HDPUG >> >> Sent from Mail for Windows 10 >> >> From: rkondner >> Sent: Tuesday, January 23, 2018 10:08 AM >> To: [log in to unmask] >> Subject: Re: [TN] soldering problems >> >> Hi, >> >> Can someone explain to me the warts associated with HASL? I know some >> would say flatness but since solder paste goes on all my boards that is >> not am issue. >> >> I am an EE and I typically run 5 to 25 boards for protos. A run of 100 >> or 250 is a big job for me. I cannot keep up with validating every >> vendor. I cannot run and verify coupons for every run. >> >> HASL has been very good to me even with low cost vendors and simple >> board storage. What am I missing. (Other than soldering problems! :-) >> >> Thanks, >> Bob K. >> >> >> On 1/22/2018 7:25 PM, Wayne Showers wrote: >> >>> IAg is not a horrible idea for a surface finish, but it does come with >>> its own warts. >>> 1) Creep Corrosion: DFR Solutions has done much research on this. >>> Primary recommendation to mitigate it is to paste all component pads >>> whether populated or not. >>> >>>> https://link.springer.com/article/10.1007/s11664-004-0025-x >>>>> >>>> 2) Move away from WS fluxes. Because RMA fluxes utilize the Rosin as a >>> suspension agent, you will get must less secondary issues with the flux >>> penetrating into unwanted areas which include under the solder mask, >>> between plating layers (This is critical for immersion silver as the silver >>> immersion process creates micro-voids and micro-pitting of the underlying >>> copper.) >>> >>> 3) Storage and Handling: Always wear clean cotton or latex gloves >>> (preferred). Cotton can trap oils and if the gloves are cleaned, many >>> detergents and fabric softeners have phosphor and sulfur compounds in them. >>> And Silver saver paper is a must. Silica desiccant and IAg are not >>> compatible. >>> >>> And as a final aside, unfortunately the days of Tin-Lead are limited >>> thanks to the tail wagging the dog over in the EU with Electronics as the >>> target. In 22 years of Electronics Manufacturing, I have had 4 issues with >>> bad ENIG or ENEPIG plating, and Roughly 40-50 issues with flux penetration >>> or entrapment including 1 recall that totaled over $1.5 Million Dollars. >>> >>>