inductor for HV flyback supply

In article <o4f058$9lu$1@dont-email.me>,
Tim Williams <tiwill@seventransistorlabs.com> wrote:
>"Tim Wescott" <seemywebsite@myfooter.really> wrote in message
>news:6PmdnYJ2pPNFQPfFnZ2dnUU7-cudnZ2d@giganews.com...
>> Is it just the fact that it's an acid that melts at soldering
>> temperatures that does it (like, could I use some other flux)?  Or is the
>> fact that it's asprin that's special?
>
>Yes and yes.  First, an organic melt helps to dissolve and loosen things
>(it's a solvent).  An acid helps, combining with oxides (and carrying them
>away in the liquid).  Acetylsalicylic acid will help further because the
>acetyl- part hydrolyzes relatively easily (even if you're not putting water
>into it, it's probably a prime part of decomposition products), giving a
>much stronger acid to dissolve crusty deposits.  (Acetic acid also forms a
>complex with copper ions, giving extra solubility over, say, nitric acid.
>Not that you'd use that for soldering.)

By far the most important aspect is that the enamel has affinity with
the aspirin, dissolving in it. The pristine copper layer underneath
the enamel then takes up solder like the best. On the other hand
with rosin you can't get through the enamel.

>
>The boiling/decomposition temperature sounds a little low, though, if it's
>sputtering and boiling away immediately.

Having done this time and again, I can't see what you mean. Are you arguing
that a tried and proven method doesn't work on theoretical grounds?

>
>That's a downside to ~pure organic compounds: the melting and boiling points
>are sharp.  Rosin is a mixture of heavier organic acids, so it's a bit
>milder (depending on "activation"), and different compounds evaporate first,
>leaving the metal protected even if the remaining goo isn't very active.

You still need rosin. The aspirin takes care of the enamel that is hard
to remove mechanically, especially on the 0.1 mm (that is 4 mil for those
imperialist) wire.

>
>Tim

P.S Oops, imperialist don't measure wire in inches, they use wire
gauge like #34.

Groetjes Albert
-- 
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
albert@spe&ar&c.xs4all.nl &=n http://home.hccnet.nl/a.w.m.van.der.horst

"Albert van der Horst" <albert@cherry.spenarnc.xs4all.nl> wrote in message 
news:o5qnlk$r2m$1@cherry.spenarnc.xs4all.nl...
>>The boiling/decomposition temperature sounds a little low, though, if it's
>>sputtering and boiling away immediately.
>
> Having done this time and again, I can't see what you mean. Are you 
> arguing
> that a tried and proven method doesn't work on theoretical grounds?

Duh.  Theory is always right.  You dare argue that? :^)

That was more about the observation that someone else had.  Which was 
probably the wrong technique.  Your mention above (just tapping it briefly) 
sounds more plausible.

FWIW, I've soldered steel using ZnCl2 and HCl before -- they evaporate 
rapidly, but the metal remains clean long enough to be wetted.  Similar 
idea!

> You still need rosin. The aspirin takes care of the enamel that is hard
> to remove mechanically, especially on the 0.1 mm (that is 4 mil for those
> imperialist) wire.

If you didn't buy Soldeaze (or whatever), I don't really know what to say; 
it's your own fault. :-p

I've never had a problem with the #37 (uh, 4.5 mil?) wire I've got, which is 
of the solderable kind.


I've also used molten potassium nitrate or chlorate, to burn away some 
rather more annoying enamels.  I think that wire is so old, it's from the 
days when they used literal enamel.

You melt some salt in a spoon, dip the wire, then quench the wire in water 
to freeze and dissolve the salt immediately.  Shiny pink copper remains!

Oh, and just don't get anything even marginally organic in the molten salt. 
Or even just a catalyst (like MnO2), in the potassium chlorate case.

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com