Karen, In reply to your questionairre:
1 No
2 No
3 Yes: On behalf of others who are experiencing these problems.
4 Almost. Keep watching this space
5 Maybe
If you apply too much solder flux to an assembly that is not then cleaned,
there MAY well be serious reliability problems.
However, of FAR GREATER concern, is the unpredictable reaction, at and below
the surface, between the solder flux and the solder resist, much less the
other chemistries the assembly may see!
I would be very interested to hear of your results.
Graham Naisbitt
Concoat Ltd Email: [log in to unmask]
Alasan House, Albany Park Tel: +44 (0)1276 691100
Camberley, Surrey GU15 2PL UK Fax: +44 (0)1276 691227
-----Original Message-----
From: TechNet On Behalf Of Karen Tellefsen
Sent: Thursday, October 09, 1997 9:41 PM
To: [log in to unmask]
Subject: [TECHNET] ASSY - Questionnaire - High frequency and solder paste
and flux residues
The electronics industry, particularly communications, has
been moving to higher frequencies and PCB's with denser circuitry.
To best of my knowledge, most manufacturers of high frequency
circuits clean after soldering to remove flux residues and
any possible deleterious effect they may have on high frequency /
high speed signals. Recently, my coworkers and I have been asked
by customers what effects certain flux residues have on high frequency
circuits, and my best answer is they have effects, but we haven't
quantified them.
I have been asked to measure the high frequency effects of solder
paste and flux residues so that Alpha Metals can provide useful
physical data on technical bulletins for flux and solder paste
products. I've been trying to educate myself by reading elementary
textbooks on RF circuits. However, I'm still not sure what kind of
physical properties of flux residues assemblers/designers of high
speed circuits want to have or how to measure them, including
electrical measurement equipment, test coupons and methodology.
I really don't want to spend > 40K on a network analyzer or a TDR
unless I am sure it will provide useful information for customers.
For these reasons, I am submitting the following questionnaire to
TechNet Any information you provide will be appreciated.
Karen Tellefsen
Alpha Metals, Inc
Jersey City, NJ
1. Do you assemble RF high frequency / high speed circuit boards?
2. If yes, what generic kind of data concerning solder paste and
flux residues would you find helpful in designing or assembling
high frequency / high speed circuits? If possible, be specific,
e.g. residue dielectric constant, microstrip TDRs with and without
residues, etc.
3. Do you measure the effects of solder paste or flux residues on
high speed circuits? If yes, how do you measure it, if no, do you
have any ideas how to measure it?
4. Do you know of any published work concerning the effect of
solder paste and flux residues on high frequency circuits? I am
particularly interested in measurement techniques, but data would
be useful also.
5. Would you like to collaborate with me on this project?
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