From Wassink:
"At relatively low temperatures, the tin-nickel layers form about as rapidly
as the tin-copper layers do, but at higher tempertures thier growth rate is
distinctly lower. At 100°C a 2um layer is formed in 50 days, at 170°C within
two days. A 10um layer is formed at 170°C in 38 days. The appearance of the
imtermetallic layers, as well as their composition, depends on the
temperatuee at which they are formed."
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian
> Sent: Wednesday, October 24, 2001 3:39 PM
> To: [log in to unmask]
> Subject: [TN] Tin/gold Intermetallic
>
>
> OK, the last one was fun. Let's see what I can "provoke" this time!
>
> There are standards for gold thickness for ENIG, "rules" for the amount of
> gold in tin/lead solder joints (~4% for tensile, ~2% for shear),
> but I have
> not found, looking into the TechNet archives or in J. Hwang's or Rahn's or
> Manko's books I don't have the Wassink et al book ;( ), what is
> the range
> of acceptable/expected intermetallic thickness for tin/nickel
> intermetallic.
> I would appreciate your input - any references and results seen
> in your own
> work. Let the discussion begin.
>
> regards,
> Bev Christian
> Research in Motion
>
> -----Original Message-----
> From: Earl Moon [mailto:[log in to unmask]]
> Sent: October 24, 2001 6:21 AM
> To: [log in to unmask]
> Subject: Re: [TN] Antw: [TN] exposing intermetallic on BGA pads...
>
>
> Guenter,
>
> I cannot believe how much I am learning every minute about
> soldering and all
> comprising it. Not at all being negative or contrary, I must have ruined
> thousands of solder joints in my long life in this business
> notwithstanding
> all the rework I've done and taught others.
>
> All I've ever been taught, done, and taught others is to remove
> the solder,
> with whatever means that works without damaging pads or board materials,
> then print paste, place components, and reflow.
>
> I've never even heard of leaving on solder or removing intermetallics -
> especially with a glass brush. I finished my last contract, seemingly
> successfully, two months ago. Can the world and all its "wonderful"
> soldering technology all of a sudden be passing me by in such a
> short time?
>
> Jeez, a glass brush. Thanks again Guenter, but I must need more help than
> even you, Bob Willis, or all other experts can give.
>
> Earl
>
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