TECHNET Archives

March 2015

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
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:
Thu, 5 Mar 2015 22:01:05 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (62 lines)
Hi Guy - ok, here is the short list and yes, I have a HUGE dislike for
brite acid tin:

Brite acid tin (electroplated)
1) grows tin whiskers like a chia pet due to the co-deposited organics in
the plating. The same co-deposited organics "boil" during a soldering
process causing lots of voids and generally poor solder joints. Very short
shelf life - three months is not uncommon. Doug and I have some great
pictures of the bubbling in one of our tutorials

Matte tin (electroplated)
1) one of the most common component finishes on components today. Lacks
thermal excursion robustness but will pass JSTD-002/003 solderability
testing from good plating processes. Can also tin whisker, less prone than
brite acid tin, but also not zero tin whiskers. Good for corrosion issues
in some product use environments. Fewer soldering ability issues with
stronger fluxes

Immersion tin
1) Has poor thermal excursion robustness but will pass JSTD-003
solderability testing. Much less propensity to tin whisker when plating
formulation includes specific inhibitors. Good for corrosion issues in some
product use environments. Very flat and good for SMT assembly. Because it
is deposited by a galvanic reaction, typical much thinner than
electroplated tin systems. This plating system is covered by the IPC-4554
specification.

Take a look in the IPC AJ 820 or the IPC -7095 standards as they both have
good sections on surface finishes including some tin plating comparisons.
And remember, the initiation of tin whiskers is a characteristic of tin
itself so all pure tin finishes, regardless of their deposition process,
can have tin whisker issues. Hope this helps.

Dave Hillman
Rockwell Collins
[log in to unmask]

On Thu, Mar 5, 2015 at 7:51 PM, Guy Ramsey <[log in to unmask]> wrote:

> Can anyone give me a nutshell difference between immersion tin for a solder
> finish and electroplated tin?
> Advantages, disadvantages as a surface finish more than the chemical and
> plating process differences.
> Thanks,
> Guy
>
>
>
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

ATOM RSS1 RSS2