Apparatus for automatic lapping control
First Claim
1. Control apparatus for a machine for lapping wafers, having at least one piezoelectric wafer, comprising:
- a. at least a first and second electrode means in and isolated from said lapping plate, said first and second electrode means being spaced in close proximity to each other and being faced with a solid dielectric material with a relative dielectric constant larger than 10 and positionable toward the lapping surface;
b. means for sensing the resonance frequency of piezoelectric wafers and means for terminating lapping when said resonance frequency reaches a predetermined relationship with a target frequency.
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Abstract
Apparatus for automatic lapping control, based on imbedding an electrode of special construction in a lapping plate of a lapping machine, including at least one piezoelectric wafer in the lapping load, sensing the resonance frequency of the piezoelectric wafers as they pass by the electrode, and automatically terminating the lapping when the resonance frequency equals or exceeds a target frequency; the special electrode construction comprising a facing of a dielectric material with a high dielectric constant and surrounded by an insulator having a low dielectric constant and an average wall thickness larger than its wall thickness at the surface of the lapping plate.
40 Citations
6 Claims
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1. Control apparatus for a machine for lapping wafers, having at least one piezoelectric wafer, comprising:
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a. at least a first and second electrode means in and isolated from said lapping plate, said first and second electrode means being spaced in close proximity to each other and being faced with a solid dielectric material with a relative dielectric constant larger than 10 and positionable toward the lapping surface; b. means for sensing the resonance frequency of piezoelectric wafers and means for terminating lapping when said resonance frequency reaches a predetermined relationship with a target frequency. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification