Leland,

There are actually several issues you need to be concerned with: The
first is actually ESD.  Humidity control is also a major component in
your ESD program.  As the humidity in your facility is reduced, the
propensity for charge generation and accumulation increases.  As per
ANSI 20/20 has the limits set at >30% RH < 70%.

The next issue is MSD.  From your statement I assume your facility never
exceeds 60%.  If it does then you have to take actions to correct and
derate all of the MSD components you have exposed to the environment.

And the third is your primary concern which is the control of your
solder paste.  This one there is no real industry standard that you need
to comply with so it is more results oriented.  If you are continuously
processing the paste and replenishing your supply you probably will not
see much change in your process.  If you are having issues with clogging
stencils, dry non-tacky paste, shifting components, etc. then you may
benefit from the added humidity.  Most print machines have an optional
humidity control system.  

If you need help justifying the expense I would suggest you add ESD and
MSD to list of reasons.  I require my EMS' to monitor and control
humidity for ESD and MSD and I recommend it for stencil printers but I
am results focused on that.  I hope this helps.  Good luck.

Russell Nowland
Alcatel-Lucent           
Advanced Manufacturing Engineer
Address: 14000 Quail Spring Parkway, Suite 300
Oklahoma City, OK 73134
email: [log in to unmask]
Desk: 405-302-1660
Cell: 405-203-0034
Fax: 405-302-1622

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: Wednesday, October 08, 2008 1:11 PM
To: [log in to unmask]
Subject: [TN] Controlled RH% Versus Screenprinting Results

Technetters,

A couple of folks in our firm are investigating several different brands
of humidification systems for possible installation at our facility.
These things aren't cheap, and can run close to 500K.

We see seasonal variation within our building of 15-20% in the winter
months, and may go as high as 55-60% in the summer.

Our paste manufacturer states their optimum printing parameter to be
50-60% RH.  Our process engineers think we'll see a vast improvement in
our screenprinting process if we pursue this project.

I'm trying to understand if this is really going to reap the rewards as
anticipated.

Does anyone have any prior experience(s) they might share?

Thanks in advance for your help!

Leland

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