|Publication number||US2411298 A|
|Publication date||Nov 19, 1946|
|Filing date||Feb 12, 1945|
|Priority date||Feb 12, 1945|
|Publication number||US 2411298 A, US 2411298A, US-A-2411298, US2411298 A, US2411298A|
|Inventors||Shore Sidney X|
|Original Assignee||Philips Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (17), Classifications (14)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Nov. 19, 1946. s, x SHQRE I 2,411,298
PIEZOELECTRIC CRYSTAL Filed Feb. 12, 1945 .STANDIIP SIDNEY X SHORE 'INVENTOR Biffi/wwf# aci agee crystal wafer for vibrating the same at a supersonic frequency thereby producing supersonic agitation of the etching solution. Electrical connections to the etching solutions are made by electrode plates iS--l6, for example, of copper. The crystal wafer i3 is completely immersed in the etching solution and to minimize direct electrical conduction between the compartments the barrier formed by the crystal wafer is preferably supplemented by means of an insulating masking element il of hard rubber which barrier extends beyond the surface of the etching solution.
In carrying out the process yin accordancewith the invention, a crystal .Wafer it is cut to the de.. sired shape and to a thickness greater than the thickness corresponding to the desired resonant frequency. 'lire rough cut wafer may then be machine lapped to a thickness value corresponding to or greater than the thickness at which heretofore the manual processing of wai-'ei' was initiated.,
For vibrating the crystal wafer at a supersonic frequency the wafer is coupled to an oscillator, for example, of the type shown in Fig. 2. The oscillator shown comprises a discharge tube 2@ having a cathode iii, a control grid 22 and an anode 2t connected in feedback relationship in known manner to an inductance-capacitance tuned circuit 2li-25 having a resonant frequency in the supersonic range, i. e.`, a resonant frequency greater than about 25 kilocycles. A selfregulating operating bias voltage for the tube 2K9 is provided by means of a grid-leak resistor 2t. Ammeter 2l serves as a grid-current indicator during operation of the oscillator. The crystal Wafer to be processed is connected across the resonant circuit 2l-25 by means of conductors aixed to the electrode plates ib-ld (see Fig. 1).
The 'cutting of the wafer from the mother crystal and the subsequent lapping thereof produces a substantial amount of disordered crystal line material in microscopic form which remains on the surface of the wafer and/or within the microscopic cavities produced by the crystalline elements protruding from the surface of the crystal, Bly immersing the wafer in an etching solution agitated at supersonic frequency the wafer is subjected simultaneously to chemical action and to the action of the kinetic energy forces iinparted to the solution by the supersonic agitationl and it is found that the disordered crystalline material is substantially completely removed as Well as those microscopic crystals which are only partially etched out by the chemical action and thus non-permanently secured to the crystal wafer.
In the preferred arrangement of my invention, the constants of the tuned circuit ffii-25 are so selected that the resonant frequency of the tuned circuit approximates the resonant frequency of the crystal Wafer whereby the crystal wafer vibrates at its resonant frequency and becomes the 1 frequency determining element of the oscillator.
frequency of the wafer compared with a signal voltage of the desired frequency derived from a frequency standard 3i. The beat frequency produced by detector St is applied to a frequency meter 3l and the etching of the wafer is terminated when the resonant frequency of the wafer f attains a predetermined value With respect to the Siti frequency of the standard 3i as indicated by the frequency meter 32.
While I have described my invention by means of specific examples and in specific embodiments I do not wish to be limited thereto for obvious modications will occur to those skilled in the art without departing from the spirit and scope Qf the invention.
What I claim l. En the manufacture of piezo-electric eiements the steps comprising immersing a crystal element in an etching solution and etching the surface of the element so immersed while similitaneously vibrating eiement and agite-.ting said solution at a supersonic frequency.
Z. in the manufacture of piezo-electric elements the steps comprising predimensioning a crystal element to a resonant frequency greater than about 25 kilocycles, immersing the predimensioned element in an etching solution, and etching the surface of said element so immersed while simultaneously'vibrating the element and agitating said solution at the resonant frequency of the element.,
3. The method of manufacturing a piezo-electric element having a predetermined resonant y frequency, comprising predimensioning a crystal Wafer to a resonant frequency greater than about 25 kilocycles, immersing the predimensioned element in an etching solution, etching the surface of said element so immersed while simultaneously vibrating the element and agitating said solution at the resonant frequencyiof the element, measuring the resonant frequency of the element, and terminating said etching when the, resonant frequency of the element equals the said predetermined resonant frequency.
d. Apparatus for processing piezoelectric elements, comprising a. vcontainer for an etching solution, means to so position the element in the container that the major surfaces of the element are exposed to the etching solution and the ele ment divides the container into two compart ments, and means to electrically connect the etching solution in each of said compartments to a source of electrical potential.
5.` Apparatus for processing piezo-electric elements, comprising a container for an etching solution, means to so position the element-in the container that the major surfaces of the element are exposed to the etching solution and the ele- Yment divides the container into two compartments, and means coupled to said element. through the etching solution to vibrate the velement at a super-sonic frequency.
6. Apparatus for processing piezo-electric elements, comprising a container for an etching solution, means to so position the element in the container that the major surfaces of the elementare exposed to the etching solution and the element divides the container into two compart' ments, means coupled to theelement through the .SENEY X, SHURE.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2493461 *||May 4, 1944||Jan 3, 1950||Harvey Wells Communications In||Means and method of forming piezo-electric crystals|
|US2746918 *||Feb 13, 1953||May 22, 1956||Collins Radio Co||Apparatus for electrolytically tuning an end wire fixture|
|US2767067 *||Nov 4, 1953||Oct 16, 1956||Arthur C Prichard||Crystal detwinning|
|US2785322 *||Aug 4, 1953||Mar 12, 1957||Bell Telephone Labor Inc||Stable liquid electrodes|
|US3107188 *||Nov 21, 1960||Oct 15, 1963||Pacific Semiconductors Inc||Process of etching semiconductors and etchant solutions used therefor|
|US3122817 *||Feb 4, 1963||Mar 3, 1964||Bell Telephone Labor Inc||Fabrication of semiconductor devices|
|US3150021 *||Jul 25, 1961||Sep 22, 1964||Nippon Electric Co||Method of manufacturing semiconductor devices|
|US3158517 *||Oct 27, 1960||Nov 24, 1964||Telefunken Gmbh||Process for forming recesses in semiconductor bodies|
|US3227952 *||Dec 22, 1960||Jan 4, 1966||Ibm||Device for controlling a process representable by electrical oscillations and including digital conversion means|
|US3276106 *||Jul 1, 1963||Oct 4, 1966||North American Aviation Inc||Preparation of multilayer boards for electrical connections between layers|
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|US3291640 *||May 27, 1963||Dec 13, 1966||Chemclean Corp||Ultrasonic cleaning process|
|US3593125 *||Jul 16, 1969||Jul 13, 1971||Shover Harry T||Crystal testing apparatus for use with an oscilloscope|
|US3975678 *||May 19, 1975||Aug 17, 1976||American Micro-Systems, Inc.||Crystal ranging apparatus for determining range within which resonant frequency of crystal lies|
|US4255228 *||Jan 5, 1979||Mar 10, 1981||The United States Of America As Represented By The Secretary Of The Army||Method of growing quartz|
|US5942100 *||Aug 25, 1997||Aug 24, 1999||Transat Corporation||Crystal etch monitor|
|US20120103520 *||Sep 23, 2011||May 3, 2012||Ah-Ram Lee||Apparatus of etching glass substrate|
|U.S. Classification||29/25.35, 331/171, 366/127, 333/141, 324/727, 216/90, 310/318, 331/158, 310/312, 324/76.41|
|International Classification||H03H3/04, H03H3/00|