John,
I was thinking of 'cleaning' after the reflow process had been done, and
immediately before the carbon ink step. ... whatever the 'cleaning' step
might be. :-)
Steve
-----Original Message-----
From: John Burke [mailto:[log in to unmask]]
Sent: Friday, August 18, 2006 1:06 PM
To: '(Leadfree Electronics Assembly Forum)'; Creswick, Steven
Subject: RE: [LF] Immersion Silver and Conductive Carbon Ink
A word of warning, any attempt to "clean" a silver board in process to
make
the carbon ink "stick" will probably render it useless by the time it
gets
to being soldered at the assembly stage. There is indeed a co-deposited
material to prevent tarnish with most of those chemistries.
John
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Creswick, Steven
Sent: Friday, August 18, 2006 9:26 AM
To: [log in to unmask]
Subject: Re: [LF] Immersion Silver and Conductive Carbon Ink
Scott,
Along Lester's line of thought, are there preservatives / anti-tarnish
constituents, etc. still on the surface? Do they have the same problem
with virgin boards [before you reflow components on them, etc.]? Or is
it worse in the virgin state?
Can they argon plasma clean [as a test], or maybe a solvent wipe of some
nature ... Solvent as best suggested by potential platers out there.
Steve
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Lester Subrattee
Sent: Friday, August 18, 2006 11:07 AM
To: [log in to unmask]
Subject: Re: [LF] Immersion Silver and Conductive Carbon Ink
Hi Scott,
I don't have a solution for your problem except to say that
you're
depositing on metal and should have no issues if it is clean. Unless the
silver is actually lifting off. I think it could be a surface prep issue
or
contamination from either the PCB house or your fabricator in handling.
Get
the surface analyzed and cleaned, then retry.
That being said, there have been studies by some OEMs that
indicate
capability of Immersion Silver as a contactable surface in lieu of gold.
That is one of the reasons Immersion Silver's popularity has increased.
Unfortunately, I don't have the details and reports but someone on the
Forum
might.
Good Luck,
LS
-----Original Message-----
From: Douglas, Scott [mailto:[log in to unmask]]
Sent: Friday, August 18, 2006 10:41 AM
To: [log in to unmask]
Subject: Immersion Silver and Conductive Carbon Ink
Fellow list persons,
=20
I have a printed circuit board used in a remote control unit. We changed
the solder plating on the board to immersion silver for RoHS compliance.
Our fabricator is having a problem getting the conductive carbon ink to
stick to the immersion silver. Is anyone aware of this type of problem?
We are trying to figure out if we just have a vendor problem or is there
some issue with the immersion silver and conductive carbon ink
combination. Any suggestions as to changes or corrective actions?
=20
As always, thank you in advance for your comments.
Scott Douglas, NCE=20
Staff Technical Specialist
Harman Specialty Group=20
3 Oak Park Drive=20
Bedford, MA 01730=20
Phone: (781) 280-0406=20
Email: [log in to unmask]
Web: www.harmanspecialtygroup.com=20
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