Soldering iron tips (UK: bits) are usually of made hardened copper. Copper
dissolves fairly rapidly in solder so modern tips are electroplated with
iron. Iron dissolves much more slowly in solder than copper but is harder to
wet. Thus the manufacturer will "tin" the tips with a very strong flux. In
use it is important not to remove the solder from this wetted area by over
wiping or whatever as it will be very difficult to re-tin with the low
activity assembly fluxes used in electronics. Some tip manufacturers plate
the non working areas of the tip with nickel to control the size of the
wetted area and help prevent the back end of the tip from sticking in the
soldering iron itself.
The canning industry only has to tin the steel once and doesn't keep it at
high temperatures thereafter. Similarly they can use any type of chemical
and any type of cleaning process they like - they don't have to worry about
SIR and stuff.
Best 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: http://Pb-Free.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian
Sent: Monday, October 22, 2001 7:34 PM
To: [log in to unmask]
Subject: Re: [TN] tin on iron and solder on iron
OK, let me try saying this a different way:
it "seems" that the canning industry has an easy time putting tin on can
steel. Why do I have trouble getting solder to stick to a properly
preheated 100% iron surface? Is it just a matter of flux strength? Or
something else?
Bev Christian
Research in Motion
-----Original Message-----
From: Mel Parrish [mailto:[log in to unmask]]
Sent: October 22, 2001 4:17 PM
To: [log in to unmask]
Subject: Re: [TN] tin on iron and solder on iron
Dr Bev,
Not sure what your question is but for discussion. Many of the common
component lead frames contain significant amounts of iron which is plated to
enhance solderability, limit corrosion, etc.. Seems that there should be
some metallurgists out there that can lead us to understanding the
solubility characteristics but my text books discuss FeSn intermetalics
although the rate is slower that that of tin gold or tin copper. Also seems
to me that the Nickel content is important to the solder interface.
Mel Parrish
Soldering Technology International
102 Tribble Drive
Madison, AL 35758
256 705 5530
256 705 5538 Fax
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Bev Christian
Sent: Friday, October 19, 2001 2:01 PM
To: [log in to unmask]
Subject: [TN] tin on iron and solder on iron
OK, here is a general question for all you met guys. But I am not sure I
can explain it well enough to be understood!
We all know that tin can be put on iron or we wouldn't have "tin" cans. I
also know it is difficult to put solder on iron. So my question is this: if
one has a tinned iron surface and it is put into molten solder the tin will
be dissolved into the molten solder. I presume when the piece of iron is
withdrawn from the pot, solder will be well adhered to the iron. Is this
because there is a solderable tin/iron intermetallic? What is the main
difference between the tin can process and putting solder directly on iron
that makes one easy to do and the other difficult? This may be a "first
grade" met question, but I don't know the answer. Thanks.
Bev Christian
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