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Re: gEDA-user: Isopropyl alcohol vs. ethanol

Karel Kulhavy wrote:
On Sun, Apr 23, 2006 at 10:51:43PM -0400, Marvin Dickens wrote:
Karel Kulhavy wrote:
Is it true that PCB's should be washed by isopropyl alcohol and not
ethanol because ethanol has small molecules that creep into the part
cases and wreak havoc there?

I've never heard of washing PCB's in ethyl alcohol or isopropyl alcohol. In fact, - Yuk.

Both isopropyl alcohol and ethyl alcohol are both reasonably flammable at 70% purity or above.
Further, isopropyl alcohol has a low vapor pressure. In the long term, without a well thought out
ventilation system, flash fires would occur (Not if- but when....).

We wash our boards in a mild solution of distilled water, clear ammonia and a mild surfactant.
This is followed with a wash with distilled water. The boards are then dried for several
hours in a drying oven.

But does ammonia dissolve rosin?
No. ammonia does not dissolve rosin.

But, that's OK: We don't use traditional rosin based solders (Rosin as in derived from pine trees and other conifers).
In fact, I don't know why anyone would use rosin based solders (Unless it is all that is available...). If you are using
solder that contains rosin, the product you are trying to remove is abietic acid that appears as a residue after soldering. Abietic acid is soluable in many alchohols.(As well as many other solvents...). Wtth that said, we use water soluable solder.
It's easier to work with and is more people/environmental friendly. Just so you know - Abietic acid is nasty.

Regarding water soluable solders, take a look at:

http://www.tselectronic.com/solder/solder.html?tse_Session=87ad1697d9d7666613a61c09428f3791

Water soluable solder paste is also readily available. In fact, water soluable solder products are available in
any form factor you can think of.



Best

Marvin