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January 2012

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Subject:
From:
"David D. Hillman" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Wed, 25 Jan 2012 07:15:43 -0600
Content-Type:
text/plain
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Hi Inge - actually we are on the same page in a big picture sense. Bob and
I have been discussing the bulk water topic in terms of water quality and
volume but one data point that we probably should have injected is why the
drying segment of a cleaning process is important. Any pwb cleaning
process not only needs to focus on the type of water used but how is that
water applied and how is the water removed. I don't think anyone of the
Technet community would disagree that a cleaning process should adequately
remove the cleaning chemistry formulation (water or solvent) in such a
manner that if any of the chemistry remains, it would not cause any
degradation of the pwb. As you described, cleaning chemistry that is
trapped in certain locations on a pwb can cause big issues regardless of
quality of the solution. The bulk water topic is an equation with a number
of variables and as our discussions have demonstrated, different variables
in the equation are more important than others for some folk's
process/product.

Dave



Inge Hernefjord <[log in to unmask]>
01/24/2012 04:54 PM

To
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
cc

Subject
Re: [TN] Bulk water discussion






I am wth you and against you, David.
dipping in clean water - no harm
dipping in the Mississippi river- not recommended
However,
there is a special case, which we have suffered from water droplets
problem, namely, narrow spaces and absorbent contaminations  under
components. In such a situation, closed-in water can take many, many hours
of drying before all water has been removed.

Inge

On 24 January 2012 18:06, David D. Hillman <[log in to unmask]>
wrote:
Hi Bob - the reason that no one is commenting on the amount of water left
on the board is that the amount of water left on the board doesn't matter.
Bulk water, regardless of water type, represents a shorting risk but not
much else. The key parameter is how does that water, whether its a ounce
or a gallon, interact with the circuit board. If the water is clean (aka
DI water) but it allows for ionic materials to be leached out of the
components/laminate it is in contact with, then there could possibly be a
product issue. If the water contains ionic materials (aka Tap water) and
those ionic materials interact with the components/laminate then there
could possibly be a product issue. The amount of water only comes a
consideration if it plays a role in the ionic transport/exchange
reactions. That is why there is such a diverse set of responses to this
subject - depending on your type of water, the interaction it initiates
and the type of circuitry on the board, you may or may not have  product
issues.

Dave Hillman
Rockwell Collins
[log in to unmask]



Robert Kondner <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
01/24/2012 09:57 AM
Please respond to
<[log in to unmask]>


To
<[log in to unmask]>
cc

Subject
Re: [TN] The iPhone Economy (from NY Times)--BACKGROUND FACTS & HISTORY
FIRST






Karen,

 No one is talking about weighing the material left behind on the board.

We are talking about weighting the amount of RINSE WATER left on an
assembled  board.

 No doubt a final ionic contamination test is desired, but let us first
figure out if the amount of rinse water left on a board represents a
significant contamination source. You can rinse in DI water but flux might
be trapped under parts. So there are several things going on and remaining
rinse water is so easy to measure with a sensitive scale.

 There seems to be so many "Analytical Folks" on this list but not a
single
person has yet to report on the amount of rinse water expected to remain
on
a loaded PCB assembly. It is shocking to say the least.

Bob K.



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen
Sent: Tuesday, January 24, 2012 10:47 AM
To: [log in to unmask]
Subject: Re: [TN] The iPhone Economy (from NY Times)--BACKGROUND FACTS &
HISTORY FIRST

Of course analysis is need to supply data when analyzing processes;
however
it's important to chose the correct analysis technique.  When it comes to
the small amount of deleterious materials left behind on a circuit after
water washing, weight gain is not a particularly sensitive analysis tool.
IPA/water extraction followed by ion chromatography would provide better
data with regard to materials on the circuit that may cause circuit
failure.
Applying elevated temperature and humidity with power on the circuit to
determine whether electrochemical failures occur may also indicate that a
circuit is not clean enough.  If a circuit board washed in tap water with
a
blow-off passes the temperature humidity power test, then it's likely that
tap water wash is good enough; if not, it might be wise to use DI water
during the wash process.

Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069






  Re: [TN] The iPhone Economy (from NY Times)--BACKGROUND FACTS & HISTORY

  FIRST


  Robert Kondner
                 to:
                   TechNet
                                                       01/24/2012 10:10
AM




  Sent by:
         TechNet <[log in to unmask]>
  Please respond to rkondner









When it comes to selecting someone to help analyze a company's processes I
will take the "Fresh Out of School" MBA over an experienced electronic
technician any day.

 When I asked about rinsing in tap water followed with a water blow off so
many folks said "Must Use DI" without even considering an analysis. A
fresh
out of school MBA might think about it longer. Hmmm I think I will pay
them
more money.

 What would they do in China? Put in a DI system of blow off tap water
with
an air gun? Hmmm, sounds like China knows the value of a dollar!

Bob K.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pete
Sent: Tuesday, January 24, 2012 9:18 AM
To: [log in to unmask]
Subject: Re: [TN] The iPhone Economy (from NY Times)--BACKGROUND FACTS &
HISTORY FIRST

There seems to be two types of MBAs.  Those that start with an undergrad
degree and get their MBA as they, and those that get their MBAs before
entering the real world.  The problem came in the 80's, when every company
wanted to hire those freshly minted MBAs right out of school.  About the
same time that share price became the only barometer.   So began a cycle
of
formulatic answers because the textbook said so.  Profits temporarily
down?
Reduce the workforce.  Wnat more profits?  Send it to China.  The MBAs
with
real experience knew better, wouldn't go for the instant gratification
ideas, so they aren't the ones who got promoted to positions to make
significant business decisions.  Part of the reason American companies
seem
to be stuck in a ditch is because we're now starting to see the long term
effects of short term efforts to prop up that share price.

I could show rather convincingly how moving some R&D workforce to China
because they bill 1/3 is costing us twice as much, and losing us market
share.  But I don't have the right letters after my name, I don't get to
go
to those meetings.

Pete

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