Indeed. There are three platings we avoid: bright tin, bright nickel and
bright gold. As all know the disadvantage with these already, I don't echo.
/Inge


----- Original Message -----
From: "Mike Fenner" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, July 01, 2010 11:57 AM
Subject: Re: [TN] Bright tin


> Third, fourth ....next
> My general rule/experience is that anything plated that is bright and
> shiny
> is pretty but not necessarily solderable. Shiny is not an intrinsic
> property
> of plated metals, but comes from all sorts of organic stuff  - none of
> which
> are solderable, and additionally may lead to out-gassing etc.
>
> Plating Sn onto Ni instead of Cu is thought to reduce stress in the
> plating
> and therefore whiskers. This is somewhat ironic:  harder to solder Nickel
> replaces easy to solder copper to avoid a problem which is introduced by
> the
> finish intended to conserve solderability.
>
> This finish is usually suggested because it suits a specific PCB supplier,
> rather than to improve your manufacturing or in-service reliability etc
>
> Regards
>
> Mike
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Wenger, George M.
> Sent: Thursday, July 01, 2010 12:14 AM
> To: [log in to unmask]
> Subject: Re: [TN] Bright tin
>
> Dave,
>
> I'll be the second dissenter right behind you.
>
> Regards,
> George
> George M. Wenger
> Senior Principal FMA  / Reliability Engineer
> Andrew Corporation - Wireless Network Solutions
> 40 Technology Drive, Warren, NJ 07059
> (908) 546-4531 Office (732) 309-8964 Mobile
> E-mail: [log in to unmask]
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
> Sent: Wednesday, June 30, 2010 5:27 PM
> To: [log in to unmask]
> Subject: Re: [TN] Bright tin
>
> Hi Rudy - I guess I'll be the voice of dissent but I would run as far away
> from bright tin as fast as possible. The industry studies demonstrating
> bright tin's ability to initiate and growth tin whiskers making a plated
> object look like a chia pet are numerous. Additionally, the co-deposited
> organic materials in a bright tin plated finish typically result in
> outgassing during soldering resulting in poor solder joints of
> questionable integrity. Steve G. had a picture several months back of  the
> result of trying to solder a bright tin plated connector. Finally, bright
> tin has poor solderability shelf life issues (as you detailed) due to
> oxidation issues. I recommend not allowing the use of bright tin on pwbs.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
>
> R Sedlak <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 06/30/2010 01:05 PM
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> R Sedlak <[log in to unmask]>
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> Re: [TN] Bright tin
>
>
>
>
>
>
> Cedric:
> Bright Tin is definitely electroplated, and as such can be much thicker
> than the more common immersion Tin, however, since it is electroplated, it
> covers the top of the pad, and there may be exposed Copper on the sides of
> the pad.
>
> Bright Tin is high in organics, which should minimize, but not eliminate,
> Tin whiskers.
>
> Nickel is normally not used under Bright Tin, although it MIGHT help shelf
> life.  Shelf life of Bright Tin finish is more controlled by oxide
> formation on surface of Tin, rather than by intermetallic formation,
> because the Tin is usually so thick.
>
> Hope this assists.
> Rudy Sedlak
> RD Chemical Company
>
> --- On Wed, 6/30/10, Cedric ORAIN <[log in to unmask]> wrote:
>
> From: Cedric ORAIN <[log in to unmask]>
> Subject: [TN] Bright tin
> To: [log in to unmask]
> Date: Wednesday, June 30, 2010, 10:03 AM
>
> Hello all,
>
> I've been proposed Bright Tin as PCB finishing. It is the first time I've
> heard about this plating for PCB.
>
> Is someone is familiar with this process and could expose drawbacks and
> benefit?
>
> Do you confirm that it is an electroplating process? Do I need to specify
> a
> Nickel barrier or something lie that underneath the tin layer? Is the
> thickness of tin is critical and has to be monitored carefully?
>
> I'm also concerned about tin whiskers with bright tin as it as been banned
> from the plating of connectors and components due to its propensity to the
> growth of whiskers.
>
> Ok, it's a lot of questions!  I just want to be advised on what is
> important
> to know about that subject.
>
> Thanks in adavance for your bright advice.
>
> Cedric ORAIN
>
>
>
>
>
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