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Publication numberUS2411298 A
Publication typeGrant
Publication dateNov 19, 1946
Filing dateFeb 12, 1945
Priority dateFeb 12, 1945
Publication numberUS 2411298 A, US 2411298A, US-A-2411298, US2411298 A, US2411298A
InventorsShore Sidney X
Original AssigneePhilips Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Piezoelectric crystal
US 2411298 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

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.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2493461 *May 4, 1944Jan 3, 1950Harvey Wells Communications InMeans and method of forming piezo-electric crystals
US2746918 *Feb 13, 1953May 22, 1956Collins Radio CoApparatus for electrolytically tuning an end wire fixture
US2767067 *Nov 4, 1953Oct 16, 1956Arthur C PrichardCrystal detwinning
US2785322 *Aug 4, 1953Mar 12, 1957Bell Telephone Labor IncStable liquid electrodes
US3107188 *Nov 21, 1960Oct 15, 1963Pacific Semiconductors IncProcess of etching semiconductors and etchant solutions used therefor
US3122817 *Feb 4, 1963Mar 3, 1964Bell Telephone Labor IncFabrication of semiconductor devices
US3150021 *Jul 25, 1961Sep 22, 1964Nippon Electric CoMethod of manufacturing semiconductor devices
US3158517 *Oct 27, 1960Nov 24, 1964Telefunken GmbhProcess for forming recesses in semiconductor bodies
US3227952 *Dec 22, 1960Jan 4, 1966IbmDevice for controlling a process representable by electrical oscillations and including digital conversion means
US3276106 *Jul 1, 1963Oct 4, 1966North American Aviation IncPreparation of multilayer boards for electrical connections between layers
US3276927 *Jul 1, 1963Oct 4, 1966North American Aviation IncSmoothing of mechanically drilled holes
US3291640 *May 27, 1963Dec 13, 1966Chemclean CorpUltrasonic cleaning process
US3593125 *Jul 16, 1969Jul 13, 1971Shover Harry TCrystal testing apparatus for use with an oscilloscope
US3975678 *May 19, 1975Aug 17, 1976American Micro-Systems, Inc.Crystal ranging apparatus for determining range within which resonant frequency of crystal lies
US4255228 *Jan 5, 1979Mar 10, 1981The United States Of America As Represented By The Secretary Of The ArmyMethod of growing quartz
US5942100 *Aug 25, 1997Aug 24, 1999Transat CorporationCrystal etch monitor
US20120103520 *Sep 23, 2011May 3, 2012Ah-Ram LeeApparatus of etching glass substrate
Classifications
U.S. Classification29/25.35, 331/171, 366/127, 333/141, 324/727, 216/90, 310/318, 331/158, 310/312, 324/76.41
International ClassificationH03H3/04, H03H3/00
Cooperative ClassificationH03H3/04
European ClassificationH03H3/04