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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