I think I'm going to join you in kind :-). It's a Campary time :-)

Vladimir
SENTEC
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca


-----Original Message-----
From: Inge <[log in to unmask]>

Date:         Sun, 5 Jul 2009 20:06:04 
To: <[log in to unmask]>
Subject: Re: [TN] Weird solder joints


Vlad - Joyce : 3 - 1
.....aaaahh....wife came with a drink...Famous Grouse+Martini+Dubonnet + 
ice......see yo 2morrou ..
Inge


----- Original Message ----- 
From: "Vladimir Igoshev" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, July 05, 2009 6:51 PM
Subject: Re: [TN] Weird solder joints


> Joyce,
>
> First of all there is no "free" Ag in SACs with less than 3.5 Ag and 
> secondly it is impossible to see ANY segregation at grain boundaries with 
> the techniques commonly used in the industry. Thirdly, I'm not aware of 
> any techniques which would allow segregation exclusively at triple 
> junction (and in essence it's just a dot in 2D !!!!).
>
> Sunday :-)
>
> Vladimir
> SENTEC
> 11 Canadian Road, Unit 7.
> Scarborough, ON M1R 5G1
> Tel: (416) 899-1882
> Fax: (905) 882-8812
> www.sentec.ca
>
>
> -----Original Message-----
> From: Joyce Koo <[log in to unmask]>
>
> Date:         Sun, 5 Jul 2009 12:12:46
> To: <[log in to unmask]>
> Subject: Re: [TN] Weird solder joints
>
>
> Too much brain on grain?  SAC has ag sagrigation in grain boundary and 
> some ppc paticles of minor additives, assume add by vendor as grain growth 
> inhibitor, in triple junction.  To assessing grain structure is possible 
> in some of the SAC I believe.  Silly brain, go back to holiday mode.  Left 
> side is shutting down.  Zzzz.
> --------------------------
> Sent using BlackBerry
>
>
> ----- Original Message -----
> From: TechNet <[log in to unmask]>
> To: [log in to unmask] <[log in to unmask]>
> Sent: Sun Jul 05 11:47:18 2009
> Subject: Re: [TN] Weird solder joints
>
> Vladimir, Gaby, Inge, Mike - People!!!  This is Sunday!!  Are we trying to
> start the work week a day earlier??
>
> It is really close for Ingemar already!
>
>
> Maybe this is the weekend troubleshooting crew!  Kind of like the weekend 
> TV
> anchor team...
>
>   I can just imagine how Dewey's response to 'grains' might be related to
> beverages.
>
>
> Gaby - At least it appears that you have gotten a fair amount of 
> information
> already this weekend - making your Monday a bit more efficient.
>
> I enjoyed the calm winds and 68-70°F temps to go flying this morning. 
> From
> the micro to the macro.  A pleasant change in perspective
>
> Enjoy the remainder of your Sunday
>
> Steve C
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
> Sent: Sunday, July 05, 2009 10:20 AM
> To: [log in to unmask]
> Subject: Re: [TN] Weird solder joints
>
> Thank you inge,
>
> Even though I believe I know a few things, a person can not know 
> everything
> :-). That is why I asked the question.
>
> Honestly, I'm still almost confused every time I hear someone referring to
> the grain structure in solder joints. I know  it's pain in the neck to
> reveal the real grain structure in solders (and even more so in Pb-free
> world, than in the eutectic one), meaning it's not a practical thing to 
> do.
>
> Therefore  I always ask the same question: "what do you mean by "grain
> structure" and almost always it turns out to be the phase (not grain)
> structure, which makes much more sense to me.
>
> Honestly, I'm not even sure whether the grain structure (which would 
> mainly
> their size inside the individual phase) plays a role in reliability of
> solder joints.
>
> In fact, a few years ago we deliberately tried to grow Sn grains in one of
> the SAC alloys and ended up with nothing - the original grain size (a few
> microns) never changed. I thought it was very interesting.
>
> Regards,
>
> Vladimir
> SENTEC
> SENTEC
> 11 Canadian Road, Unit 7.
> Scarborough, ON M1R 5G1
> Tel: (416) 899-1882
> Fax: (905) 882-8812
> www.sentec.ca
>
>
> -----Original Message-----
> From: Inge <[log in to unmask]>
>
> Date:         Sun, 5 Jul 2009 10:42:49
> To: <[log in to unmask]>
> Subject: Re: [TN] Weird solder joints
>
>
> Vlad,
>
> 1. the alloy members have solidified evenly all through the ball
> 2. the distribution of phases are even
> 3. the grains are fine
>
> you'd know it well, being a guru yaself
>
> Inge
>
>
> ----- Original Message ----- 
> From: <[log in to unmask]>
> To: "TechNet E-Mail Forum" <[log in to unmask]>; "Inge"
> <[log in to unmask]>
> Sent: Saturday, July 04, 2009 11:06 PM
> Subject: Re: [TN] Weird solder joints
>
>
>> Inge,
>>
>> Could you elaborate on what you mean by "good grain structure"?
>>
>> Thanks,
>>
>> Vladimir
>> SENTEC
>> SENTEC
>> 11 Canadian Road, Unit 7.
>> Scarborough, ON M1R 5G1
>> Tel: (416) 899-1882
>> Fax: (905) 882-8812
>> www.sentec.ca
>>
>>
>> -----Original Message-----
>> From: Inge <[log in to unmask]>
>>
>> Date:         Sat, 4 Jul 2009 20:48:31
>> To: <[log in to unmask]>
>> Subject: Re: [TN] Weird solder joints
>>
>>
>> Gaby,
>> solder joints are often expected to be perfect and according to the 
>> school
>> book, but in the real world they are more or less imperfekt.
>> Plus:
>> good geomtry
>> good wetting
>> good surface formation
>> no big dendrites
>> no big voids
>> good nickel barrier
>> good grain structure
>>
>> Minus
>> flux inclusions wich have not have time enough to withdraw to the 
>> surface.
>> I think you have got a too dry paste. I've seen similar solder joints and
>> we had no problems. If we had, some boards ought to show up after years
>> of operation.
>>
>> I can't see any reason to panic, your solder joints are rather normal. Do
>> this: take the polished
>> crossection samples and put then in a jar with a flux remover. Place the
>> jar
>> in a water filled ultrasonic tank and let go for a minute. If the 'dark'
>> streaks disappear, it's certainly flux.
>>
>> It's  good for all to know how strong and longlasting solder joints can 
>> be
>> despite numerous 'anomalies' as brother Creswick call them.I've tested
>> solder joints with up to 50% voids...and they have been nearly as good as
>> normal ones. Because the metallurgical properties have been good.
>>
>> Finally, judging solder joints from light microscope images demands a 
>> very
>> experienced eye. If I were you , i.e. young and sweet and uncertain , I'd
>> fine polish the samples, etch in a weak solution for a minute and have
>> them
>> placed in a SEM. Does not take many minutes to get a safer platform for
>> determination.
>>
>>
>> Inge
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Gabriela" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Saturday, July 04, 2009 9:54 AM
>> Subject: [TN] Weird solder joints
>>
>>
>>> Dear all,
>>> By cross sectioning BGA solder joints on a failed assembly, I found that
>>> the
>>> suspected joints are not uniform and that they contain unusual 
>>> separation
>>> areas.
>>>
>>> I suspect mixed assembly and/or bad reflow profile.
>>>
>>> Steve was so kind and enabled me to send the links.
>>> Please may I have your opinion?
>>> http://stevezeva.homestead.com/files/small.jpg
>>>
>>>
>>>
>>> <http://stevezeva.homestead.com/files/small1.jpg>
>>> http://stevezeva.homestead.com/files/small1.jpg
>>>
>>>
>>>
>>> <http://stevezeva.homestead.com/files/small2.jpg>
>>> http://stevezeva.homestead.com/files/small2.jpg
>>>
>>> http://stevezeva.homestead.com/files/small3.jpg
>>>
>>> <http://stevezeva.homestead.com/files/small4.jpg>
>>> http://stevezeva.homestead.com/files/small4.jpg
>>>
>>>
>>>
>>>
>>> Gaby
>>>
>>>
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