A via pad which has no clearance flash in the soldermask. It is "tented"
by the soldermask. Typically this is done on both sides of the via. It
is considered poor practice to tent one side only due to the high
probability of entrapment of corrosive materials during fabrication and
assembly. The usage of tented vias provides insulation between the via
pad and a stationary conductive surface (typically on an electrical
component or an adhesive mounted heatsink) which would otherwise create
an electrical short. Since the polymer based material of soldermask is
not chafe resistant, such a provision should seldom be relied upon for
stationary components and never be relied upon for any component subject
to vibration.
When employing tented vias beneath adhesive mounted heatsinks, consider
the application of powder coating your heatsink with H.B. Fuller Light
Gray Epoxy PN IF-870. This technique insures electrical isolation of
conductors on the heatsink mounting side of your PCB.
Chris Taylor
Senior Printed Circuit Designer
LXE, Inc.
125 Technology Parkway
Norcross, GA 30092
voice: (770) 447-4224 X3242
fax: (770) 447-6928
e-mail: [log in to unmask]


>----------
>From:  Craig M. Lang/AEC[SMTP:[log in to unmask]]
>Sent:  Monday, January 12, 1998 7:57 AM
>To:    [log in to unmask]
>Subject:       [DC] Tented Via?
>
>The last posts on 'Question on Plated Holes' have led me to ask what a
>'tented via' is.  Thanks to all who can tell me!
>
>
>Sincerely,
>
>Craig M. Lang, Engineer
>Applied Electro-Optics Corporation
>E-mail: [log in to unmask]
>
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