On Sat, 30 Aug 2003 08:34:08 +0100, Leon Heller <
leon_heller@...>
wrote:
>
> ----- Original Message ----- From: "mumin55555" <MUMIN55555@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, August 29, 2003 2:12 PM
> Subject: [Homebrew_PCBs] but is "soldering paste" ok to use?
>
>
>> hallo again!
>> i read your answers, thanks a lot. but here, in israel there are
>> almost no electronics stors, and the ones existing, do not have a
>> lot of stuff. so what is flux? is "electronics
>> solder" is the same as "solder paste" that i can get here?
>
> Electronic solder is like wire (made from a tin/lead alloy-usually 60%
> tin
> and 40% lead) with a flux (typically resin) core. The flux core melts
> with
> the solder when the soldering iron is applied and cleans the metal of
> oxides
> etc. helping the solder to flow properly and wet the parts to be joined.
> Resin flux leaves a residue which can look a bit messy. It may be removed
> by
> scrubbing with a brush and solvent, like iso-propyl alcohol. You can also
> get 'low-residue' solder which uses a different flux, which mostly
> evaporates when soldering, and doesn't need cleaning. It doesn't work as
> well as resin, in my experience.
>
> Solder paste consists of solder powder mixed with flux and is applied to
> PCBs when assembling surface mount components.
>
> Leon
> --
> Leon Heller, G1HSM
> leon_heller@...
> http://www.geocities.com/leon_heller
but washing of proper flux (colophony) is only for making it look better.
it doesn't corrode the metals and it is not conductive (at least with non-
critical circuits).
maybe when doing hf work of very sensitive high impedance circuits wash it
off.
most time when i make boards only for me i don't wash it of. too lazy.
it may be a good idea to test the circuit before cleaning it. (to avoid
recleaning).
i have also seen big differences in flux used.
sometimes it makes a real mess, dark brown stuff everywhere, sometimes
it is not darker than the pcb.
this depends of soldering speed, flux type used in the wire, amount of
flux,
and also it depends very of the iron temperature.
if it is too hot you get darker (more burnt) flux residue.
if i make a nice clean circuit on a fresh pcb with new components there is
not too much mess.
if you solder it quick and have the right temperature is doesn't get ugly.
but when doing repairs (desoldering components, solder another in again
etc.)
most time it needs cleaning afterwards.
i think the flux residue is no disadvantage. it prevents corrosion and
helps when you need to get the part out of the pcb again...
i hope you find a supplier for what you need.
Austria is a small country too but within the EU i can get things easy.
most time from germany if i can't find them here.
but there are plenty of mail order companies and even some small stores in
big cities which carry these things.
st
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