Technetters,

    I would really appreciate comments and experiences from the Technet users on
the topic of unplugged vias. The situation is a PWB with .010 vias, unplugged,
but later wave soldered. It is a double sided SMT assembly. The first step is to
screen print and convection reflow the top side SMT parts, then invert, glue
dot, place, cure, invert and wave the glue dotted chip caps. At the same time we
will be filling the .010 vias, some of which are under SMT components.

    Is cleanliness an issue with a solvent based heated cleaner? Is cleanliness
an issue with a Westkleen saponified in-line cleaner? The flux is RMA. We are
not ready for alternative fluxes here yet.

    Might the flow in the via leave a residual pressure on the topside SMT
components? Are there other concerns I haven't imagined yet?

    The vias will be used as test points because the application, according to
the EEs, cannot handle all the antenae that using traces to test pads would
provide.

    Any comments are most welcome.

    And, thank you.

Stu Korringa
Smiths Industries
Grand Rapids, Mi.
[log in to unmask]
616-241-8189

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