cleaning the boards

[Steve Harrison]

At 09:30 AM 1999-12-15 -0500, George Maier wrote:
>Kevin:
>A long time ago I took a NASA sponsored course in hand soldering
techniques.  I doubt that
>the basics have changed but you never know.  Anyway, their take (and mine
ever since) on
>cleaning boards and soldered connections in general has been to use 99%
pure isopropyl
>alcohol.  The stuff from the drug store is only 90% at best, and leaves
some residue.
>I've been able to find quart containers of the good stuff in electronic
parts stores.
>You'll need a box of Q-Tips and some alcohol brushes - you know, the ones
with a metallic
>grip, and fairly stiff bristles.

I agree. Actually, the best at the drug store is 91%; there's also 70%,
useless for nearly anything. I now keep a bottle of alcohol on my workbench
in one of those little reagent plastic squirt bottles. Another bottle has
water for the soldering iron sponge. Another is actual flux cleaner stuff,
which works marginally better than the alcohol but definitely leaves no
residue of its own.

Unfortunately, however, even the 99%-pure stuff can leave a board looking
really bad. I noticed some years ago that when a board was cleaned with
something (never figured out what it was) and then cleaned again later with
even a good flux remover spray, sometimes it would cloud up, looking
really, really bad. The cloudy film would appear all over EVERYTHING, even
components. Same thing sometimes happens with the alky. Nowadays, when I
need to clean a board with unknown history, I first start with just a small
area to see what happens. If it clouds up, I let it be. The white film
that's left, whatever it is, can be scraped off but seems to be impervious
to further cleaning by anything, stiff bristles or no.

I wonder if the drug store can order the 99%-pure alky (maybe even
available behind the counter)?? Should be a lot cheaper than from the
electronics stores, which don't like to carry it anyhow since they have
flux cleaners that are more expensive and so bring a higher profit, I
think. The stores of the 1990's no longer stock according to what the
CONSUMER wants to buy: they stock only what sells fast and brings the
highest profit. Hard to blame them: it's really easy to fall behind the
times and go bankrupt by carrying old, obsolete products whose value is
known and appreciated to only a few old-timers and which carry no "sex"
appeal to the youngsters. I think that's one reason the mail-order stores
still do a land-office business these days: they have stuffs the stores
flatly refuse to carry any longer.

73, Steve K0XP

Sponsored by the City of Tempe 

Listserver Submissions:  heath at listserv.tempe.gov
Listserver Subscription: listserv at listserv.tempe.gov - "subscribe heath 'name' 'call'"
Listserver Unsubscribe: listserv at listserv.tempe.gov - -"signoff heath"