Assuming it is a wave soldering process, a Pealable Solder Mask placed
over the TH on the wave side could work.
Consult your PWB manufacturer for dimensions and process compliance.
Mickey
_____
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Friday, November 28, 2008 5:08 PM
To: TechNet E-Mail Forum; weiner, mickey
Subject: Re: [TN] Tenting of vias and spare PTH
Tenting the vias could inpact testability and reduces the ability to
clean.
The safest solution is to use a batch cleaner with Kyzen or Envirogold
316 flux cleaner 5% with Di water. These saponifers reduce the surface
tension of water and are excellent cleaners. The boards must be cleaned
in the aqueous cleaner within ten minutes to remove the caustic soap.
Kyzen in Manchester NH makes this cleaner and sells the Kyzen
saponifier. The use of the batch cleaner allows you to use the existing
aqueous cleaner and not contaminate the cleaner with saponifers that
cloud the glass windows and require down time to descale the heaters of
the tank with the saponifier.
John Goulet
Sr Manufacturing Engineer
-------------- Original message --------------
From: "weiner, mickey" <[log in to unmask]>
> Bogert
> What is the final finish of this board
>
>
> Mickey
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of - bogert
> Sent: Thursday, November 27, 2008 5:05 PM
> To: [log in to unmask]
> Subject: [TN] Tenting of vias and spare PTH
>
> We have an existing design PWA with socket mounted parts. The
design
> has vias under the sockets as well as PTH under the sockets
that were
> intended for use as spares to facilitate future design
changes. The
> sockets are of the open construction frame type (an H
configuration), or
> otherwise are body-less sockets. We are considering removing
all
> sockets and direct soldering the compo nents into the existing
PTH using
> ORL0 type flux.
>
> We are concerned about flux residue and other forms of
contamination
> such as from the PWB manufacturing process and the PWA
assembly process
> getting into the open via and spare PTH and not being removed
by the
> in-line cleaning system.
>
> We are considering having the vias and spare PTH tented in
some fashion.
> We need to retain use of the tented spare PTH for future use
if needed.
> What method do folks recommend to tent vias on equipment that
was
> already designed with un-tented vias and spare PTH?
>
> On a go forward basis, we are considering mandating that if
vias are
> used under components, they must be tented and we will not
allow spare
> PTH under any component. Allowing spare PTH under open frome
or
> bodyless sockets was a dumb idea.
>
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