Yannick,
ISO does not guarantee quality so I wouldn't be trying to satisfy ISO as
much as I would like to manage the quality of the end product. If the end
product quality is good, you can document your process, follow the
documentation and fully satisfy ISO.

Depending on the importance of time and money you can do a full analysis of
every jar of incoming paste and also a full analysis of used paste to insure
its condition. This is probably not feasible.

My initial stance on incoming paste quality is to have the supplier provide
a Certificate of Conformance. If the solder always performs you don't have
to do any testing yourself. When the paste does not meet expectations you
can include your supplier in the analysis and corrective action as part of
your quality system.

As far as used paste I would try to use a simple system of time. In other
words define "usage" time frames that maintain the paste's performance based
on experience, document, train and follow procedures.

This is a very simplistic approach that I have used successfully for the
past 10 years. I satisfy the ISO requirements and produce quality product.
Others may disagree and suggest more sophisticated procedures.

Joel Mearig
Delta Tau Data Systems, Inc.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Yannick Brisson
Sent: Thursday, November 10, 2005 11:57 AM
To: [log in to unmask]
Subject: [TN] Solder paste control

Hi,

        I had a question from our ISO guy asking me how I know that the
paste we use is in good condition?  The problem is that he saw our operator
put some old paste back in a empty jar to reuse it the next day. So his
question is how do you know the paste has been on the stencil below the
maximal hour wrote in the datasheet?  Do you know any measure than I can
take to certify that the paste in good? like viscosity or something else?
And how I do that?  Because I'm pretty sure that is next question will be
how I know the new paste we just receive is good too.

Thank You

Yannick


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