Re: Hydrobromic Acid
Most fluxes which list Hydrobromic acid as an ingredient also contain Hydrazine. The reason why Hydrobromic is used is that it is one of the few acids which forms soluble salts with Hydrazine. When the Hydrobromic and Hydrazine are mixed, a compound called Hydrazine Hydrobromide is formed, and this compound is not a known carcinogen, so if it is present at levels less than 1%, it does not need to be listed on the MSDS.
I mention this because at temperature, the Hydrazine Hydrobromide breaks down, and volatilizes, and is not something I would recommend inhaling too much of. Although, you can emulate a former US president, who "did not inhale"!
Rudy Sedlak
RD Chemical Company
--- On Fri, 9/18/09, Paul Edwards <[log in to unmask]> wrote:
From: Paul Edwards <[log in to unmask]>
Subject: Re: [TN] Black Pad
To: [log in to unmask]
Date: Friday, September 18, 2009, 9:38 AM
This effect can also appear if the PCBs have been baked...
Then good luck soldering to the PCBs with anything other than hydrobromic acid...
Paul
Paul Edwards
Surface Art Engineering
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, September 18, 2009 6:54 AM
To: [log in to unmask]
Subject: Re: [TN] Black Pad
Hi Rudy - actually, if the copper and tin form an intermetallic phase
during your first pass thru the reflow oven (which they should) then you
would have solderability issues during subsequent soldering operations.
Dave Hillman
Rockwell Collins
[log in to unmask]
R Sedlak <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
09/18/2009 08:44 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
R Sedlak <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Black Pad
Linda:
Actually, it is quite possible to get black immersion Tin. It comes from
running a bath with an excess of Cupric Copper in it. I wrote a article
on how to monitor Cupric Copper in immersion Tin baths to avoid this in a
recent PCD&F magazine.
The black color should not affect solderability, as it is actually
immersion Copper on top of the Tin.
Rudy Sedlak
RD Chemical Company
--- On Fri, 9/18/09, Linda Langley <[log in to unmask]> wrote:
From: Linda Langley <[log in to unmask]>
Subject: [TN] Black Pad
To: [log in to unmask]
Date: Friday, September 18, 2009, 3:12 AM
I know we have had this subject many times before so I did go to the
archives and still can't find an answer. My question, is Black Pad only
associated with ENIG? Is it possible with immersion Tin?
Linda Langley CIT
Training Specialist
Jabil Circuit
248-292-6176
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