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May 2003

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Subject:
From:
Mike Fenner <[log in to unmask]>
Reply To:
Date:
Tue, 13 May 2003 11:24:07 +0100
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This is an it depends question. With respect to the board only I would be
thinking on these lines:

When soldering HASL you are really reflowing a pre-made joint, so the solder
on the board just has to coalesce with the solder in the paste.

When you are soldering ENIG the gold has dissolve as you say and then you
have to wet the nickel. The energy time required to do this is more/longer
than a simple coalescence (and more than for soldering to copper).

So the "it depends" comes in when considering how much margin there is in
your existing profile/paste or combination. If the profile is just enough
for HASL you might have to up it a bit for ENIG.

Overall: you are also making joints to component leads as well, and these
will have a variety of finishes which your profile will be accommodating so
the picture is not quite as clear cut, what you have done for those will
likely encompass to a greater or lesser extent the ENIG.

You need to be aware anyway, that even if you don't have to change anything,
your operating window closes a little from HASL to ENIG



Regards

Mike Fenner

Applications Engineer, European Operations
Indium Corporation
T: + 44 1908 580 400
M: + 44 7810 526 317
F: + 44 1908 580 411
E: [log in to unmask]
W: www.indium.com
Leadfree: www.Pb-Free.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of
[log in to unmask]
Sent: Tuesday, May 13, 2003 1:14 AM
To: [log in to unmask]
Subject: Re: [TN] ENIG reflow profile vs HASL


Hi, Chris,

Not sure how you've arrived at your information that ENIG boards require
higher temperatures than HASL boards - after all, it's the solder you're
melting, not the plated finish. The profile used by our CEM takes board
temp up to 208 C for both HASL and ENIG.

Peter



Chris Murphy <[log in to unmask]>    13/05/2003 07:32 AM
Sent by: TechNet <[log in to unmask]>

Please respond to "TechNet E-Mail Forum."; Please respond to Chris Murphy

              To:  [log in to unmask]
              cc:  (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
              Subject: [TN] ENIG reflow profile vs HASL








Hi Technetters,

looking through the Technet archives on the differences between HASL and
ENIG
boards, I notice that higher temeperatures are required for soldering ENIG
boards.

Presumably this is because the gold layer firstly has to be dissolved, and
we are
dealing with a Ni/Sn intermetallic rather than a Cu/Sn intermetallic.

Does anyone have any recommendations on what differences have to be made to
the
reflow profile (e.g. different times above 183 deg C or 200 deg C)?  Or can
the same
profile be used for the same board regardless of whether it is HASL or
ENIG?

Thanks in advance for any replies.

Regards,

Chris Murphy,
Production Engineering,
Tait Electronics

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