Yes, but after it is ACTIVATED it becomes inert, but never completely. Solder paste flux residues are pretty inert after going through reflow. Liquid benchtop fluxes are still active if left on because not all of the flux is activated by the heat from a soldering iron, and thus inerted.
Flux residues never heated are still very active.
Flux residues from cored wire solder are so concentrated that they are fully heated during soldering, thus are activated, and when finished soldering are pretty much inert but again, no flux is ever 100% activated/inerted by a thermal cycle.
-----Original Message-----
From: Robert Kondner [mailto:[log in to unmask]]
Sent: Thursday, April 26, 2012 3:36 PM
To: 'TechNet E-Mail Forum'; Stadem, Richard D.
Subject: RE: [TN] Cleaning non-clean paste
Well,
1 You heat flux to ACTIVATE flux. (Activate as in make chemically active for oxide film removal.)
2 Not heating a No Clean flux does not leave activated chemicals. If so No Clean wire solder would be useless as hand soldering does not chemically react all the flux in the solder. RMA wire solder is a good example.
If anyone can site a manufacturers data sheet or any No Clean flux product that requires cleaning after use that would be serious input to this discussion.
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Thursday, April 26, 2012 4:23 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning non-clean paste
May I amend that a little bit?
Here is what I would say:
Ideal scenario would be to either use a flux meant to be cleaned, then clean, or to not clean a no-clean flux, PROVIDED IT HAS BEEN SUBJECTED TO HEAT TO INERT (DE-ACTIVATE) IT.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of R Sedlak
Sent: Thursday, April 26, 2012 3:09 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning non-clean paste
Fabien: All replies so far have been excellent. I want to underline that a no-clean flux, being formulated to not require cleaning, will by its nature be much more difficult to clean than a flux meant to be cleaned, so it is highly probable you are leaving at least some flux residue on the board. Ideal scenario would be to either use a flux meant to be cleaned, then clean, or to not clean a no-clean flux.
Rudy Sedlak
RD Chemical Company
--- On Thu, 4/26/12, Fabien Guizelin <[log in to unmask]> wrote:
From: Fabien Guizelin <[log in to unmask]>
Subject: [TN] Cleaning non-clean paste
To: [log in to unmask]
Date: Thursday, April 26, 2012, 6:40 AM
Hi,
Can you summarize the risks linked to cleaning a non-clean paste ?
I am concerned by incomplete cleaning of the non-clean leaving active residue on the board.
We are using Inudium 5.1 (non-clean, Pb free), cleaned with Vigon A250.
We are using non-clean because of experience of that paste (internally and at EMS shop) and we are cleaning to promote underfill bonding.
Thanks,
Fabien
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