[SI-LIST] AW: Re: AW: Effects of flux on board performance

I found "Solder Flux Basics" contributed by Paul D. Stransky. See attached
.pdf
Don't leave flux residue. Resistance and capacitance varies with climate and
time.
No reliable data for calculations or simulations.

Thomas Beneken

-----Ursprüngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]Im Auftrag von Larry Miller
Gesendet: Dienstag, 18. Dezember 2001 16:17
An: 'beneken@xxxxxxxxxxxx'; emiguel@xxxxxxxxxx; 'Si-List (E-mail)'
Betreff: [SI-LIST] Re: AW: Effects of flux on board performance



Unfortunately, it depends on how much flux is trapped.

There are two aspects to this:

1. Contamination affects signal characteristics; analog circuits or anything
high impedance is most severely affected. The effect is crosstalk or leakage
and is mostly resistive. A/D converters and op amps are very much affected.

2. Long term (months to years) the flux residue is corrosive and will
destroy traces and connections.

The U.S. Military has very stringent requirements for flux removal, to the
extent of requiring use of de-ionized water and passing conductivity tests.

The general rule for leaving flux residue is: Don't.

Larry Miller


-----Original Message-----
From: Thomas Beneken [mailto:beneken@xxxxxxxxxxxx]
Sent: Tuesday, December 18, 2001 5:57 AM
To: emiguel@xxxxxxxxxx; 'Si-List (E-mail)'
Subject: [SI-LIST] AW: Effects of flux on board performance



IPC Institute for Interconnecting and Packaging Electronic Circuits
http://www.ipc.org/

-----Urspr=FCngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]Im Auftrag von Ed Miguel
Gesendet: Donnerstag, 13. Dezember 2001 19:34
An: Si-List (E-mail)
Betreff: [SI-LIST] Effects of flux on board performance



Hello,

I wonder if anyone can point me in a direction where I can find informati=
on
regarding the effect of flux residue left on PCB's?   I need to consider
the effects of flux trapped under a small BGA.  I am specifically looking
for some resistive or capacitance values.  If you have any suggestions
please let me know.

Thanks,

Ed

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