where the gold come from?  is it thicker than 0.1 micron plated  
form?  Is it immersion gold or electroless?  (the dissolution rate  
for plated/electroless/immersion are very different... not mention  
the organic complex exist on some of the surfaces)...
                                   jk
On Jan 16, 2008, at 5:24 PM, Bev Christian wrote:

> Dave,
> I only have 0.8 to 1.2% gold in the solder balls - as determined by  
> XRF.
> Bev
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
> Sent: Wednesday, January 16, 2008 5:06 PM
> To: [log in to unmask]
> Subject: Re: [TN] SV: [TN] SV: [TN] Solderability of Tin-Gold  
> Intermetallic
>
> Hi gang! Steve - I just sent you another set of photos showing a  
> solder
> joint that has gold embrittlement. Bev - if you have a solder joint  
> that
> contains the AuSn4 microstructure phase then you have an indication  
> that
> your overall composition has exceeded the "magical" 4% limit.  The
> presence of the AuSn4 platelets cause the solder joint to behave in a
> brittle manner when subjected to some use environments. The  
> formation of
> the AuSn4 phase isn't going to interfere with the formation of your  
> solder
> joint but they do result in solder joint integrity degradation. The
> pretinning of gold plated component leads is an attempt to replace the
> gold with a solder coating and lower the overall total percentage  
> of gold
> that would exist in the solder joint - the lower the overall solder  
> joint
> gold content, the lower the likelihood for the AuSn4 phase to form.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
>
> Steve Gregory <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 01/16/2008 03:35 PM
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> Steve Gregory <[log in to unmask]>
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> Re: [TN] SV: [TN] SV: [TN] Solderability of Tin-Gold Intermetallic
>
>
>
>
>
>
> Hi Inge ol' pal!
>
> I went back and looked on my pages, and am not sure if they're still
> there. But one of these might be:
>
> http://stevezeva.homestead.com/files/fracture_bad.jpg
>
> http://stevezeva.homestead.com/files/fracture_bad_2.jpg
>
>
> Steve
>
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord
> Sent: Wednesday, January 16, 2008 3:09 PM
> To: [log in to unmask]
> Subject: [TN] SV: [TN] SV: [TN] Solderability of Tin-Gold  
> Intermetallic
>
> Not really true, the Scottish blood in my veines tells me to be  
> careful
> with money, the kyrgise blood makes me crush the table, therefore,  
> noone
> can actually be under it.
>
> I think there are pictures from my large AuSn platelets somewhere on
> Gregory's wall. If not, I can probably dig them up again from some old
> report. If such crystals are abundant in a solder joint, the  
> components
> may just jump off the board when giving a mechanical shock.
>
> /Inge
>
> -----Ursprungligt meddelande-----
> Från: TechNet [mailto:[log in to unmask]] För Werner Engelmaier /*
> Skickat: den 16 januari 2008 20:30
> Till: [log in to unmask]
> Ämne: Re: [TN] SV: [TN] Solderability of Tin-Gold Intermetallic
>
> Hi Inge,
> As usual people are well advised not to argue with a (this) Swede;  
> 1) he
> usually knows what he is talking about, and 2) if not, he will  
> drink you
> under the table.
> The IMCs formed by Sn/Pb, and Sn/Ag as well, are platellet-shaped  
> crystals
> (in cross-section they may look like needles but are always  
> plateletts),
> and I have seen no evidence that they are solderable. Solderability  
> simply
> depends on how much Sn, or SnPb, to which you wet, is present. So the
> amount of these IMCs affect both solderability as well as
> Au/Ag-embrittlement.
> Inge, how is Gerd? I sure have not heard anything about him for  
> some time.
>
>
>
> Werner
>
>
>
> **************
> Start the year off right.  Easy ways to stay in shape.
>
> http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489
>
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