I find it interesting that the use of tap water is still being proposed. Let's look at the residues in tap water in industrial regions. High levels of chloride, sulfate and and sodium and processing  through sand filtration creating soluble silica globules that hold concentrated pockets of contaminants.  This approached worked with rosin based fluxes in the 90s.  But lets look at the level of circuit sensitivity of today's hardware (where a half meg ohm drift will shut down a critical circuit and maybe the entire system) and the effect of residues that are moisture absorbing and conductive are creating performance problems. I propose that we run a series of evaluations comparing tap water, to RO water to DI water. Then i propose that we evaluate the results by ion chromatography using both the C3 localized extractions and bag extractions of our Umpire 2 SIR test board. Using the IPC SIR conditions of 40C/93% with continuous monitoring to assess the residue effects. Oh yes it's true that the resistivity drops to nothing but not due ionic contamination that is found in tap water but the absorption of CO2 that has no residual effect on the active circuitry. Oh and if you paid attention I suggested the the board be rinsed with DI water steam and not tested in my lab so how much simpler can that be. 

Terry Munson
Foresite Inc
765-457-8095


On Jan 8, 2012, at 8:11 PM, "Robert Kondner" <[log in to unmask]> wrote:

> Before you go through the expense and effort of doing DI to clean and rinse
> try doing a tap clean and rinse WITH a blow off cycle. Have some ionic
> contamination tests run afterwards, they will be very clean if you have a
> good blow off.
> 
> Washing with Di water is kind of silly, how long does Di water remain DI
> after a wash of dirty boards start?  Maybe 100 ms? Wash with tap.
> 
> Rinse in DI might help but a blow off of tap water leaves only tiny amounts
> of material even with very hard tap water. It really depends on water
> entrapment issues and then even a rinse is questionable.
> 
> Try something simple and measure.
> 
> Bob K.
> 
> 
> 
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Terry Munson
> Sent: Saturday, January 07, 2012 7:44 PM
> To: [log in to unmask]
> Subject: Re: [TN] Cleaning water soluble flux‏
> 
> They should look at DI water steam to clean and rinse.  We have effectively
> cleaned 2331-ZX flux. With stop steam cleaning. Call me at 765-457-8095.  
> 
> Terry Munson
> Foresite
> 765-457-8095
> 
> 
> On Jan 7, 2012, at 6:36 PM, Gary Bremer <[log in to unmask]> wrote:
> 
>> I am presently working as an contractor for the next few months then back
> to unemployment, last place I worked was Jet Propulsion Laboratory on the
> Mars Science Laboratory.  These are lighted panels for various aircraft and
> the company policy is for J-STD-001/IPC-A-610 Class 3  The failure is with
> miniature T-1 lamps that stop working after going through an baking process.
> Other boards that use these lamps but use RMA flux do not have this problem,
> I suspect the cleaning process and the flux.  They do not check ionic
> contamination and handle the boards with bare hands and the operators even
> know when components are ESD sensitive or not.  I have recommended they
> change the cleaning process to an Aqueous type batch cleaner but this cost
> money which they do not wish to spend.  Their process person believes that
> their process is fine and something else is causing the problem (bad lamps,
> forming lamp leads, etc.).  This goes against all my knowledge and training.
>> 
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