You're correct that's a tough job.
If this phase of evaluating pastes, our test is a relative comparison of how
well pastes wet. It is not a measure of how well a component pad will wet
in production.
In the test:
* Clean (i.e., chemically or with abrasion) the tarnish from a sheet of bare
copper laminate.
* Print the paste on the laminate, using a stencil used in evaluating
pastes. [Check with Phil Zarro for a recommendation.]
* Reflow solder the laminate using the paste manufacturer's recommended
profile.
* Clean the laminate with isopropyl alcohol.
* Inspect the solder fillet at X10 magnification.
Dave Fish
----- Original Message -----
From: "Lou Hart" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, December 17, 2001 1:07 PM
Subject: [TN] Solder paste evaluation
> TechNetters, our production people want to investigate an alternative to
> the solder paste we are now using. My proposal was to perform a designed
> experiment to see if the candidate paste is better than, worse than, or
> equivalent to the present paste.
>
> Factors to consider in an experiment could, in my opinion, include the
> pastes themselves, solderability preservative, lead finish, stencil life,
> etc.
>
> A big question than comes to my mind is: what measurement do we use for
> soldering performance? Is there a variable measurement? I'd rather not
> use an attribute measurement, since that, as you know, requires a
> relatively large sample size. I don't like the prospect of using any
> subjective measurement, fearing gage uncertainty will be excessive.
>
> Any comments would be most welcome. Contact me off-line for discussions
if
> this topic is too narrow for the forum. Thanks to all. Lou Hart
>
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