I am using an inline cleaner, initially supplied with fresh DI water in tank
1, 2 & 3. The PWB then passes through an air knife drying process. How
"clean" does my DI need to be? I initially measure the resistivity but it
obviously becomes "conductive" as the water is processed. So what would be a
resistivity that one could say is "too conductive" - or is there such a
number? I do periodically perform a ROSE test with good results. Is the
purity of the DI water used in cleaning up to me to determine, as long as I
pass the ROSE test?
Doug
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas O. Pauls
Sent: Thursday, March 17, 2005 10:59 AM
To: [log in to unmask]
Subject: Re: [TN] DI Water
I would agree with Joe. I would use at least 2 megohm-cm (0.5 uS/cm)
resistivity water. I would not go higher than 10 megohm-cm because the
water starts to get too "hungry" can can start to attack stainless steel.
I do not know of any IPC specifications on water quality, but we will be
starting on revisions to the J-STD-001 Handbook and perhaps we can fold that
in. Keep in mind that cleaning is a solubility equation. It is not just
water quality that is important but temperatures, pressure, flow rates, etc.
Doug Pauls
Joe Russeau
<jrusseau@PRECISI
ONANALYSTS.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
03/17/2005 09:39 Re: [TN] DI Water
AM
Please respond to
TechNet E-Mail
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; Please respond
to
Joe Russeau
<jrusseau@PRECISI
ONANALYSTS.COM>
Hello,
Obviously the higher the resistivity of the DI water the more effective the
cleaning. Using water in the 2-10 Megohm-cm range is usually sufficient for
water purity. We usually recommend leaning towards the higher end of that
range for better cleaning, but it depends on your water system and set-up as
to the level of quality that can be reached.
As far as specs, I am not aware of any industry specs or guidelines for DI
water quality, but that does not mean that none exist. Some of the other
Tech guru's may have more information on that front.
Best Regards,
Joe Russeau
Process Analyst
Precision Analytical Laboratory
----- Original Message -----
From: "SUBSCRIBE TechNet Doug" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, March 17, 2005 9:26 AM
Subject: [TN] DI Water
> How "clean" does my DI water need to be for cleaning water soluble
> flux from PWB assemblies? Is there an industry minimum guideline?
>
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