The sealed variety of TACT switch that you are looking at is
manufactured by the company that I work for at the moment!!
These are superior in many ways to other TACT switches in
the market. I have some surface mount ones here that I used
on an project several months ago that have the silicon rubber
actuator. The photos below show this switch and its internals.
The leads that you see on the bottom are part of a two piece
lead frame that is moulded directly into the hard plastic of
the base piece. In the base piece there is a round cavity
where the dome switch sits. It contacts on the two outer
contacts that are shown. When the actuator is pushed the dome
snaps down and contacts on the center post. Note that the two
outer contacts are both part of one side of the lead frame
and are not using the dome disk to make the connections
beteeen the two common contacts on that side of the switch
package. In like manner the center post is connected to the
other two switch contacts via the other half of the two piece
lead frame.



Michael Karas