Lei,
1) I  would say that "Dip and Look" is not the preferred method of
solderability testing for fine pitch devices.  Probably the preferred method
could best be described as: "let's not look and hope it works".  In partial
defense of this "method", if you drop your bad suppliers, work with the
so-so ones to get them up to where the good ones are, you can avoid a lot of
testing.  I still don't believe you can eliminate it.

2) I believe that a round robin study conducted by the J-004 solderability
sub-committee showed that the reproducibility of wetting balances was not
the best, but not bad enough to throw them all out the window either.  These
are tricky little suckers, not liking uncontrolled room conditions,
especially air drafts.  Variations from part to part also make comparison
studies difficult.  If they are talking about problems getting proper
readings from hanging static weights then I would question whether or not
someone has bent the shaft going through the transducer (been there, done
that).

We use the wetting balance quite a bit, but you have to live with a pretty
good spread of data.

regards,
Bev Christian
Nortel
> ----------
> From:         Tumibay, Aleli[SMTP:[log in to unmask]]
> Sent:         Tuesday, October 20, 1998 7:59 PM
> To:   [log in to unmask]
> Subject:      [TN] Solderability Test for SMT: Dip and Look or Wetting
> Balance?
>
> Hello to all the people in this list.  I hope you can help me.
>
> 1. Now that the direction the industry is taking is towards the
> development of packages with reduced lead widths (primarily because of
> the shrinking package size),  is the "Dip and Look" method still the
> preferred test for Solderability Test?
>
> 2. I have asked around other assembly companies and those who purchased
> the Wetting Balance system told me that they are unable to qualify the
> machine because of  "calibration problems" and never got to use it since
> it was purchased.   Do we have somebody here who encountered similar
> problems?  Was it ever resolved?  How?
>
> If there are suppliers of various Solderability Testers here, kindly
> e-mail me privately ([log in to unmask]).   Thanks a lot.
> Best Regards,
>
>
>
> Lei Tumibay
> Lead Finish Group - Assembly Engineering
> Analog Devices - General Trias
> Cavite, Philippines
> E-mail: [log in to unmask]
>
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