Nancy:

I agree with Allan.  IPC specs allow for loss of solder mask when applied over melting metals.
Many LPI solder mask suppliers will not recommend (at least will recommend avoiding) application
of their masks over melting metals.  Depending on your design, HASL and SMOBC or one of the
alternative finishes with SMOBC should be used.  If you are using surface mount components, I
strongly recommend against applying solder mask over melting metals.  The darned (substitute your
favorite pejorative) solder reflows during soldering (wave or reflow) and wicks paste down the
circuits (under the mask).  This makes solder joint volume control very difficult and raises
concerns about assembly reliability.

Don Vischulis
[log in to unmask]

Cash, Alan wrote:

> Are you really looking for a solder resist that will adhere to the molten
> metal surface?  I would not recommend solder resist over a meltable surface.
> Try SMOBC.
>                               Al Cash
> > ----------
> > From:         Byrns Nancy[SMTP:[log in to unmask]]
> > Reply To:     TechNet E-Mail Forum.;Byrns Nancy
> > Sent:         Wednesday, May 06, 1998 8:43 AM
> > To:   [log in to unmask]
> > Subject:      [TN] IPC-D-275 conductor width .100"
> >
> > Hi everybody
> >
> > We have Rigid Printed Board, class 3 for military we need to do.
> > We refer to IPC-D-275 paragraph 5.5.1 solder resist coating because we
> > have a conductor width 0.100" and the coating completely cover this
> > conductor.
> > We want to know which pattern we should use to have a good solder resist
> > coating adhesion to the melting metal surface??
> > Which pattern are normally use in production for those conductor width??
> >
> > Thanks you,
> > Nancy Byrns
> > Oerlikon Aerospace

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