Guarded tub enclosure

1. A probe station comprising:

(a) a chuck surface for supporting a first surface of a device under test, said chuck surface having a chuck surface area;

(b) a support for a probe arranged to engage an opposed second surface of said device under test; and

(c) a conductive member interposed between and spaced apart from said chuck surface and said support, said conductive member coextensive with a major portion of said chuck surface area and including a portion constrained to move in conjunction with a lateral movement of said chuck surface, said conductive member further comprising a portion movable relative to said chuck surface and defining an aperture through which a probe can project to engage said device under test.

2. The probe station of claim 1 wherein said conductive member is coextensive with at least 60 percent of said chuck surface area.

3. The probe station of claim 1 wherein said conductive member is coextensive with at least 70 percent of said chuck surface area.

4. The probe station of claim 1 wherein said conductive member further comprises:

(a) a first plate member secured to move laterally in conjunction with said lateral movement of said chuck surface and including portions defining a first aperture; and

(b) a second plate member supported by and moveable relative to said first plate member and including a portion defining a second aperture, said probe projectable through a portion of said second aperture coincident with a portion of said first aperture.

5. The probe station of claim 4 further comprising a constraint to movement of said second plate relative to said support.

6. The probe station of claim 1 wherein a chuck comprising said chuck surface is, with the exception of said aperture, substantially enclosed by said conductive member and a tub affixed to said conductive member.