Mercury probe and method
AssigneeMSI Electronics Inc.
InventorCarl Shulman
Life of this patent
Estimating the term…
Abstract
The disclosed mercury probe has a mercury reservoir and one or more passages extending from the reservoir to an aperture plate for engaging a test wafer. Dross that tends to form at the wafer-contact end of the mercury passage(s) is removed by returning all of the mercury in the passage(s) into the reservoir, where the dross is captured. Means is provided to introduce air into the passage(s) between the reservoir and the aperture(s) of the aperture plate, for disconnecting the mercury-probe segment(s) of the mercury from the reservoir and, where there are plural mercury-probe segments, for disconnecting them from each other.
Claims17
The method of operating mercury probe apparatus of the type having at least one contact aperture in an aperture plate for engagement with a test wafer, a mercury reservoir and passage means between said aperture and the reservoir, the passage means having an opening into the reservoir below the level of the mercury therein, the contact aperture being above the level of the mercury in the reservoir so that the mercury is normally retracted from the contact aperture by gravity, said method including the steps of applying a pressure difference between the contact aperture and the upper surface of the mercury in the reservoir for thereby shifting mercury from the reservoir to the aperture to form at least one mercury-probe contact, electrically testing the wafer, and terminating said pressure difference for thereby allowing mercury in the passage means to descend from the contact aperture, said method including the further step of adjusting the level of the mercury in the reservoir so that said opening of the passage means into the reservoir is not deeper than about the level at which the buoyant force of the mercury at said opening tending to cause mercury to enter the passage means is balanced by the surface tension of the mercury across the opening whereby, when the pressure difference is terminated, mercury is expelled from the passage means into the reservoir for retention therein with any dross that may have entered said aperture.
Mercury-probe apparatus including an aperture plate having an aperture therein for defining a mercury-probe contact to a test wafer placed against the aperture plate, means including mercury when present in said aperture for making electrical test connection to a test wafer, a mercury reservoir, passage means between the aperture and the reservoir, and means operable sequentially for causing mercury to shift from the reservoir to said aperture preparatory to performing tests on the wafer and operable after the tests for causing the mercury in the passage means to shift reversely until it has been emptied into the reservoir together with dross that may have entered said aperture, an end of said passage means having an opening into the reservoir at a level below the surface of the mercury therein, said opening being limited to a depth not greater than about that at which the buoyant force tending to cause the mercury to enter the passage means is balanced by the surface tension of the mercury across said opening.
Mercury-probe apparatus including an aperture plate having an aperture therein for defining a mercury probe contact to a test wafer, a mercury reservoir, passage means between the reservoir and said aperture including an opening of the passage means into the reservoir below the level of the mercury in the reservoir, at least a portion of said passage means being a segment of insulation, means for developing a pressure difference between the reservoir and the aperture for causing the passage means to fill with mercury from the reservoir, means including mercury when present in the passage segment extending to the aperture for providing electrical test connection to the wafer, and means for inserting electrical insulation in the mercury in the insulation segment of the passage means for disconnecting the reservoir electrically from the mercury in said passage segment extending to said aperture, said apparatus comprising means for emptying the passage means of mercury so that mercury from the reservoir reaches said aperture as aforesaid in each succeeding test.
Dependencies are inferred from the claim text.