Yep, your pictures are great evidence of brite acid tin outgassing during
soldering. I still use those photos in a couple of my ppts.

Dave

On Fri, Mar 6, 2015 at 9:38 AM, Steve Gregory <[log in to unmask]> wrote:

> Hi Dave!
>
> Ahh yes, remember a while back when I was working in Tulsa the time I had
> issues with a AMP Densipac connector that I had posted about that you
> answered for me? You were thinking that it was bright tin. Below are the
> photos and the email thread...
>
> Steve
>
> http://stevezeva.homestead.com/files/AMP_Connectors.jpg
>
> http://stevezeva.homestead.com/files/Connector_Blumpies.jpg
>
> ********************************************************
>
> Steve Gregory <[log in to unmask]
> <http://listserv.ipc.org/scripts/wa.exe?LOGON=A3%3Dind0906%26L%3DTECHNET%26E%3Dquoted-printable%26P%3D4384754%26B%3D--%26T%3Dtext%252Fplain%3B%2520charset%3Dus-ascii%26header%3D1>>
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> 06/23/2009 06:49 AM
> Please respond to TechNet E-Mail Forum <[log in to unmask]
> <http://listserv.ipc.org/scripts/wa.exe?LOGON=A3%3Dind0906%26L%3DTECHNET%26E%3Dquoted-printable%26P%3D4384754%26B%3D--%26T%3Dtext%252Fplain%3B%2520charset%3Dus-ascii%26header%3D1>>;
>
> Please respond to Steve Gregory <[log in to unmask]
> <http://listserv.ipc.org/scripts/wa.exe?LOGON=A3%3Dind0906%26L%3DTECHNET%26E%3Dquoted-printable%26P%3D4384754%26B%3D--%26T%3Dtext%252Fplain%3B%2520charset%3Dus-ascii%26header%3D1>>
>
>
> Subject [TN] "Blumpie" looking connector leads...
>
> Morning all!
>
> Trying to stay cool here! Broke 100 degrees yesterday and Sunday, and it's
> probably going to break 100 degrees today. Summer has come with a
> vengeance! Ran across something yesterday that I've never seen before. We
> build a board that uses this AMP Densipac SMT connector. We've built a lot
> of these boards before without any issues at all. This latest run we have
> something going on with these particular connectors.
>
> Here's a photo of them on the PCB:
> http://stevezeva.homestead.com/files/AMP_Connectors.jpg You can probably
> see that the leads have this "Blumpie" look to them...both bumpy and lumpy.
> This is fresh out of the reflow oven. Here's a closer look:
> http://stevezeva.homestead.com/files/Connector_Blumpies.jpg
>
> If you notice the two pins either side of the white line look fine. They
> are the anchor pins that are for mechanical strength for the
> connector...they are not I/O pins. The rest of the board looks absolutely
> fine too. Not a bit of problem. It's just the I/O pins. We have noticed
> that connectors with certain date codes don't have this problem. Also,
> before reflow the connectors look okay. Luckily we've only built a few
> boards, and we're stopping until we can get to the bottom of this... Have
> any of you ever seen "blumpie" connectors like these before?
>
> Steve
>
> *********************************************************
>
> From: [log in to unmask]
> <http://listserv.ipc.org/scripts/wa.exe?LOGON=A3%3Dind0906%26L%3DTECHNET%26E%3Dquoted-printable%26P%3D4384754%26B%3D--%26T%3Dtext%252Fplain%3B%2520charset%3Dus-ascii%26header%3D1>
> [mailto:[log in to unmask]
> Sent: Tuesday, June 23, 2009 7:22 AM
> To: TechNet E-Mail Forum; Steve Gregory Cc: [log in to unmask]
> <http://listserv.ipc.org/scripts/wa.exe?LOGON=A3%3Dind0906%26L%3DTECHNET%26E%3Dquoted-printable%26P%3D4384754%26B%3D--%26T%3Dtext%252Fplain%3B%2520charset%3Dus-ascii%26header%3D1>
>
> Subject: Re: [TN] "Blumpie" looking connector leads...
>
> Hi Steve - ah, the beauty of being a materials engineer is that the
> industry doesn't seem to learn from past material mistakes so I really
> don't need to learn anything new! I recommend you check with your connector
> vendor to confirm that the connector surface plating is bright acid tin.
> The photos appear to show a bright acid tin surface finish that has
> blistered during the solder reflow process due to excessive co-deposited
> organic material. Bright acid tin finishes (plated correctly) look very
> nice but have terrible solderability characteristics and are a known tin
> whisker generation source. It appears that you may have had a surface
> plating change from what you normally had been procuring. Good luck.
>
> Dave Hillman
> Rockwell Collins
>
>
>
> On Thu, Mar 5, 2015 at 9:01 PM, David Hillman <
> [log in to unmask]> wrote:
>
>> 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
>> >
>> >
>> >
>> >
>> >
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