Where do you lease them? How much?
What is the range of measurement you make and how sensitive are the scales?
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, January 09, 2012 10:02 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning water soluble fluxþ
Every quarter or so, I lease a precision balance and perform moisture
removal charting per the methods we outlined in IPC 1601 on new bare PWBs in
order to determine the optimum bake time. I do not currently have the leased
scale.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Monday, January 09, 2012 8:52 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning water soluble fluxþ
Karen,
Got a scale?
Ob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen
Sent: Monday, January 09, 2012 9:36 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning water soluble fluxþ
It's been my experience that I get better SIR measurements when I clean my
SIR coupons with good DI water that when I wash the coupons with water form
DI tanks that need replacing. While a hot tap water wash, followed by a
compressed air blow off, followed by a room temperature DI rinse and
another compressed air blow off may adequately clean this flux residue from
this circuit and leave an electrochemically reliable circuit, it is my
opinion that the final rinse using good DI water (1 M ohm cm or better) is
needed for this operation.
Karen Tellefsen - Electrical Testing
[log in to unmask]
Re: [TN] Cleaning water soluble fluxþ
Robert Kondner
to:
TechNet
01/09/2012 08:36 AM
Sent by:
TechNet <[log in to unmask]>
Please respond to rkondner
Terry,
You pooh-pooh tap water but failed to state two important parameters:
1. Dissolved content in tap water. Let's assume it is all ionic in nature.
(500mg / L Seems like worst case)
2. Amount of water that remains on a board (average per sq. inch) after
blow off.
I would love to see the results of a test as you propose. Let us not argue
like CAD Monkeys, let us do an experiment.
I would ask that you weight the PCB after the final blow off of tap water
and then after a hot air dry, the difference being retained tap water
residue. I am very curious as to the weight of tap water contained on a
board after blow off. That should directly relate to final ionic residue and
water ionic content.
I do not have a scale here that is sensitive to where I can measure the
difference. I hope you do.
Does ANYONE on this list have a PCB, water, air gun, oven and sensitive
scale?
Can anyone suggest a sensitive scale I can buy for not too much money? Is
so I will buy one and test.
Thanks,
Bob Kondner
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Terry Munso
Sent: Sunday, January 08, 2012 10:51 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning water soluble fluxþ
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 fluxþ
>
> 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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