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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, David Hillman <[log in to unmask]>
Date:
Tue, 23 Jan 2018 09:58:58 -0600
Content-Type:
text/plain
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text/plain (120 lines)
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.
>>>
>>>

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