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2 % Silver: When a silver alloy is recommended?
The 2% silver is required when soldering to silver or silver plated
components/leads. The small percent of silver in the solder prevents
the silver on the leads from migrating into the solder resulting in a
weak or brittle solder connection.
Pin Holes: Pin holes often appear on the surface of solder joints.
How are they formed?
Pin holes are formed as a result of moisture entrapment. All that is
required is a tiny amount of moisture. When the solder comes in
contact with the through-hole, component lead, wire or whatever is
being soldered, the water boils and it forms a gas bubble that will
either escape or be trapped as the solder solidifies.
Sn60 vs. Sn63: When is the use of one of these two alloys more
appropriate than the other?
The Sn60Pb40 has a plastic range and puts down a slightly thicker
coating of solder. Sn60 is often preferred for lead tinning and other
solder coating applications. Sn63Pb37 is eutectic and as such has no
plastic range. Generally it flows better than the Sn60 and is the
preferred alloy for wave soldering and surface mount applications.
Gold Colored Solder: Assemblers are often concerned when they see a
gold color on the surface of a solder pot.
The gold color is tin oxide. When the surface of the molten solder is
exposed to air it oxidizes and turns gold; sometimes the tin oxide is
a purple-blue color. This is normal and can only be prevented by
using an anti-oxidant powder or pellet. The discoloration is a
cosmetic defect and in no way degrades the reliability of the solder.
Kester offers the #5744 Dross eliminator for this purpose.
On Jul 21, 2014, at 3:54 PM, Steve Gregory wrote:
> Hi Dick!
>
> Got your picture posted, it's here:
>
> http://stevezeva.homestead.com/Blue_Colored_Solder_Joints.JPG
>
> Steve
>
>
> On Mon, Jul 21, 2014 at 1:22 PM, Richard Krug <[log in to unmask]>
> wrote:
>
>> Steve - Please post sample picture of blue colored solder joints.
>>
>> Dick Krug, CSSBB, CSMTPE
>> Lead Process Engineer
>> Sparton Brooksville, LLC
>> 30167 Power Line Road
>> Brooksville, FL 34602-8299
>> p (352) 540-4012 (Internal Ext. 2012)
>> [log in to unmask]
>>
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
>> Sent: Monday, July 21, 2014 2:31 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] Blue Colored Solder Joints - Possible Causes
>>
>> Hi Dave!
>>
>> Got your "Barney Boards" presentation and it's posted here:
>>
>> http://stevezeva.homestead.com/Case_studies_Barney_boards.ppt
>>
>> Steve
>>
>>
>> On Mon, Jul 21, 2014 at 11:00 AM, David Hillman <
>> [log in to unmask]> wrote:
>>
>>> Hi Steve - here is Doug's and my picture of purple solder joints
>>> out
>>> of one of our ppts you can post:
>>>
>>> Dave
>>>
>>>
>>> On Mon, Jul 21, 2014 at 10:43 AM, Steve Gregory <[log in to unmask]>
>>> wrote:
>>>
>>>> Hi Dick!
>>>>
>>>> I've seen that too after cleaning with some really good DI water. I
>>>> had solder joints that turned purple on me one time, but they
>>>> weren't
>>>> wave soldered, and it was on a ENIG board and I was using a water
>>>> soluble SAC
>>>> 305 paste. Here are some pictures of what I was experiencing:
>>>>
>>>> http://stevezeva.homestead.com/Trippy_Solder.jpg
>>>>
>>>> http://stevezeva.homestead.com/Trippy_Solder_Close.jpg
>>>>
>>>> I could "Buff" the purple color away with a stiff bristled solder
>>>> joint just as long as I polished the surface well. Here are some
>>>> before and after pictures of that:
>>>>
>>>> http://stevezeva.homestead.com/Before_Buffing.jpg
>>>>
>>>> http://stevezeva.homestead.com/After_Buffing.jpg
>>>>
>>>> It wasn't a residue, because I measured the cleanliness with an
>>>> omegameter and it was negligible, and the solder appeared the same.
>>>>
>>>> Then a fellow Technetter; George M. Wenger of Failure Signature &
>>>> Characterization Lab graciously offered to analyze this for me and
>>>> here's his report:
>>>>
>>>> http://stevezeva.homestead.com/FSC-5178.ppt
>>>>
>>>> Steve
>>>>
>>>>
>>>> On Mon, Jul 21, 2014 at 8:29 AM, Richard Krug <[log in to unmask]>
>> wrote:
>>>>
>>>>> We have recently discovered some CCA's with a distinctive,
>>>>> transparent blue color on the solder joints. Viewed perpendicular
>>>>> to the solder
>>>> joint
>>>>> surface, surface looks normal. The solder surface appears blue
>>>>> when
>>>> viewed
>>>>> at an angle. I see no residues at up to 30x magnification.
>>>>> Boards
>>>>> were wave soldered using Sn63Pb37 solder with ORH1 flux, then
>>>>> in-line water washed with a low concentration of a saponifier as
>>>>> one of our common assembly processes.
>>>>>
>>>>> Any ideas of what the condition is or what caused it?
>>>>>
>>>>> Dick Krug, CSSBB, CSMTPE
>>>>> Lead Process Engineer
>>>>> Sparton Brooksville, LLC
>>>>> 30167 Power Line Road
>>>>> Brooksville, FL 34602-8299
>>>>> p (352) 540-4012 (Internal Ext. 2012) [log in to unmask]
>>>>>
>>>>> __________________________________________________________________
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>>>>> ___
>>>>>
>>>>
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