Jacob,  all responsible engineering involves trade offs.  the trick is
not throwing out the baby with the bath water, eh?  If things are
working well with the immersion AU, why switch?  While it's true that
"nothing solders like solder", your motives to switch should require
more than a claim.  Your particular design may or may not lend itself to
the HASL process.  If it does, the cost savings could be significant.
But, be prepared for some flexability in the quality area, as the
acceptability criteria will be less cut and dried than AU.  We have seen
specs from "coverage" to one mil. depending on design and process
compatability.  Don't forget that the "real" issue is Solderability. One
size does not fit all and your mileage may vary.

Mark Simmons, V-Score Central

"" wrote:

>
>
> Technetter,
>
> Recently, we're asked to change our boards finishing from immersion
> gold to HASL due to to some claims that HASL finishing is better in
> sense of joint adhesion for the BGA & QFP component. How true is that?
>
> To my knowledge, HASL boards is troublesome too as it has surface
> coplanarity issue.
>
> Is it right to say that the coplanarity of the solder is measured
> using the solder thickness measurement from 250 microinch to 750
> microinch.
>
> Regards,
>
> JACOB PAO KING HING
> Supplier Quality Engineer,