Kevin,

That depends on the class product you are building/repairing and what kind
of environment your boards are used in.

I have used water-soluble flux and then a rosin or no-clean flux afterwards
for touch-up work and it really comes down to cleanliness.  If the
water-soluble flux residue is removed thoroughly, then it should not be a
problem using a different flux for touch up, but as it has been said, it
depends (sorry for any copyright infringement).

What I recommend is do your own tests.  Examine any field failures which
have been previously reworked and look for any corrosion or residues in the
reworked areas.  Although the reworked area may appear to be clean (using a
microscope), sometimes any undesired residues are not seen until a unit has
been in the field for a while.


The gurus with the chemical degrees and the millenia of experience can
probably explain it better.

Ramon, you're a sharp cookie with a lot of experience, care to chime in?

David


>From: Kevin <[log in to unmask]>
>Reply-To: TechNet E-Mail Forum <[log in to unmask]>,              Kevin
><[log in to unmask]>
>To: [log in to unmask]
>Subject: [TN] Mixing Fluxes: Water Sol and Rosin
>Date: Mon, 3 Oct 2005 11:34:53 -0500
>
>Is it acceptable to mix flux types on a single piece of hardware?  I have
>background in MIL/AERO requirements of the "rosin only" creedo.  My past
>experience is with rosin types only, to avoid all the emotional customer
>issues and testing requirements.  However, I am now working for a company
>and their SOPs dictate use of WS at first solder, followed by water
>clean.  They then dictate rosin for any touchup, with hand clean only.  Is
>there a risk in mixing water sol and rosin on a single piece of hardware?
>What about resin and rosin?
>
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