US3789263A - Rf filters with glass on a substrate - Google Patents

Rf filters with glass on a substrate Download PDF

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Publication number
US3789263A
US3789263A US00223624A US3789263DA US3789263A US 3789263 A US3789263 A US 3789263A US 00223624 A US00223624 A US 00223624A US 3789263D A US3789263D A US 3789263DA US 3789263 A US3789263 A US 3789263A
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United States
Prior art keywords
filter
substrate
dielectric layer
glass
filament
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00223624A
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English (en)
Inventor
N Sanders
W Fritz
J Tiley
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TE Connectivity Corp
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AMP Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
    • H01R13/66—Structural association with built-in electrical component
    • H01R13/719—Structural association with built-in electrical component specially adapted for high frequency, e.g. with filters
    • H01R13/7197—Structural association with built-in electrical component specially adapted for high frequency, e.g. with filters with filters integral with or fitted onto contacts, e.g. tubular filters
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
    • C04B35/465—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates
    • C04B35/468—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates
    • C04B35/4682—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates based on BaTiO3 perovskite phase
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/215—Frequency-selective devices, e.g. filters using ferromagnetic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
    • H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
    • H01R13/66—Structural association with built-in electrical component
    • H01R13/719—Structural association with built-in electrical component specially adapted for high frequency, e.g. with filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H1/00—Constructional details of impedance networks whose electrical mode of operation is not specified or applicable to more than one type of network
    • H03H1/0007—Constructional details of impedance networks whose electrical mode of operation is not specified or applicable to more than one type of network of radio frequency interference filters

Definitions

  • ABSTRACT A low pass RF filter for high voltage feed-through to the filament of a magnetron.
  • the filter comprises a ferrite substrate in the form of a sleeve with the outer surface of the sleeve carrying a dielectric layer comprising a lead oxide glass.
  • the dielectric layer also comprises aluminum oxide to provide a rough surface for metal plating without increasing the coefficient of thermal expansion of the dielectric layer relative to the ferrite substrate.
  • This invention relates to low pass RF filters and more particularly to low pass RF filters having a substrate carrying a dielectric material.
  • This invention also relates to low pass filters for high voltage feed-through applications.
  • the filament of the microwave oven magnetron is supplied with a high voltage from the filament transformer. Unless a low pass RF filter is utilized, it is possible for rnicrowave energy to be propagated back to and along the power supply line creating a risk of radiation as warned by the Department of Health, Education and Welfare.
  • a dielectric layer comprising barium titanate is carried by a ferrite substrate in the form of a tube or sleeve.
  • the barium titanate is particularly desirable since it is relatively low cost and corrosion resistant.
  • it may be electrophoretically deposited on the substrate to assure a uniform self-leveling dielectric layer.
  • barium titanate makes it ill-suited for many high voltage feed-through applications, e.g., a microwave filter for use with the high voltage filament of a magnetron in a microwave oven.
  • Tests on barium titanate indicate that it will undergo a breakdown with sustained use at a voltage of 600 to 700 volts which is the operating range of the magnetron filament on a microwave oven.
  • many materials which could conceivably be substituted for the barium titanate exhibit leakage at the high ambient temperatures generated by the microwave oven. Other materials do not provide the desired electrical characteristics and other properties which are exhibited by the filter disclosed in the aforesaid Fritz application.
  • a low pass RF filter of one specific embodiment comprises a ferrite substrate carrying a dielectric layer comprising glass.
  • the glass is characterized by low leakage at ambient temperatures in excess of 200C.
  • a lead oxide glass is particularly well suited for this purpose since it is characterized by low leakage due to a low migration of sodium ions at these ambient temperatures.
  • the ferrite substrate is in the form of a tube and the dielectric layer including the glass is carried on the outer surface of the tube.
  • the dielectric layer further comprises aluminum oxide (A1 0 so as to provide a dielectric layer with a rough surface permitting metal plating thereon. Since aluminum oxidehas a coefficient of expansion less than the ferrite substrate, the addition of aluminum oxide does not adversely affect the compressive force between the glass and the ferrite substrate.
  • the dielectric layer is uniformly applied to the substrate without pin holes through the dielectric layer. This is accomplished by the electrophoretic deposition of the dielectric layer.
  • the central opening in the tube of the filter receives a connector pin associated with the high voltage filament of a magnetron which may be used as a source of microwave energy in a microwave oven.
  • the filter is effective to prevent the microwave energy from the magnetron from propagating back to and along the power supply line for the oven at the high ambient temperatures and operating voltages encountered in this particular application.
  • FIG. 1 is an axially sectioned view of a filter constructed in accordance with the present invention
  • FIG. 2 is an axially sectioned view of a connector assembly utilizing the filter of FIG. 1;
  • FIG. 3 is a schematic diagram of a magnetron system wherein the filter of FIGS. 1- and 2 is utilized in conjunction with the magnetron filament.
  • a filter constructed in accordance with this invention will now be described with reference to FIGS. 1 and 2.
  • a substrate in the form of an extruded ferrite 10 carries a dielectric layer 12 comprising a glass characterized by low electrical leakage at ambient temperatures of 200 to 300C and operating voltages of 600 to 700 volts.
  • Metal plating 14 is applied to the glass 12 and the ferrite 10 along its axial opening 6. Gaps 18 and 20 are left in the metal plating 14 to isolate the pin 22, which is received in the axial opening 6, from the ground plane 24.
  • a lead oxide glass may be utilized in the dielectric layer 12 to obtain the desired low leakage at high ambient temperatures.
  • a soft, Gl2 glass such as the KGl2 manufactured and sold by Owens-Illinois and 0120 glass manufactured and sold by Corning Glass Works may be utilized. These glasses are particularly advantageous since they are corrosive resistant at ambient temperatures of 200C to 300C and are also commercially available at a relatively reasonable cost.
  • a lead oxide glass such as G12 which is a low sodium glass displays the necessary low leakage characteristics at ambient temperatures of 200C 300C since there is little sodium ion migration through the glass.
  • the glass of the dielectric layer 12 is characterized by a coefficient of thermal expansion which is only slightly less than the coefficient of thermal expansion for the ferrite substrate 10, 90x10" per C as compared with 100 10" to ll 10"" per C at room temperature. These relative coefficients of thermal expansion establish a compressive force between the dielectric layer 12 and the ferrite substrate to improve the mechanical strength of the glass.
  • the dielectric layer 12 includes aluminum oxide (Al- 0 which provides a rough outer surface to permit adhesion of the metal plating l4, e.g., silver, to the dielectric layer 12.
  • Aluminum oxide is particularly desirable since it too has a coefficient of thermal expansion which is less than the ferrite substrate so as not to adversely affect the compressive force between the dielectric layer 12 and the ferrite substrate 10.
  • the dielectric layer 12 is uniformly applied to the substrate 10 without any pin holes through the layer 12. This is accomplished by ball milling the glass for some 16 hours and then passing the glass through a 200 mesh screen. This is followed by the electrophoretic deposition of the glass and aluminum oxide using a slurry made with an organic solvent which will not adversely affect the glass components of the slurry to any appreciable degree. Ethyl acetate has been found to be particularly wellsuited for use as the organic solvent when utilized. in accordance with the electrophoretic deposition process described in the Senderoff et al. U.S. Pat. No. 2,843,541. The filter is then fired in a suitable atmosphere such as nitrogen, argon or air and at a temperature sufficient to fire the glass particles into a smooth dense layer. However, the firing temperature must not be too high to avoid damaging the ferrite.
  • a suitable atmosphere such as nitrogen, argon or air
  • ferrite substrate has been described, it will be understood that other high magnetic permeability, resistive substrates may be utilized.
  • a doped semiconductive ceramic materialmight be utilized as disclosed in the aforesaid application Ser. No.
  • the electrical characteristics of a filter constructed in accordance with this invention compare quite favorably with the excellent electrical characteristics of the filter described in the-aforesaid Fritz application Ser. No. 88,042.
  • the filter of this invention exhibits an attenuation of 20dB at 915 MI-L. which is more than adequate to prevent any microwave radiation hazard due to the propogation of microwave energy from the magnetron filament back to-the power supply line.
  • FIGS. 1 and 2 The filter of FIGS. 1 and 2 will now be described as part of a source of microwave energy which is particularly well suited for use in a microwave oven.
  • a system comprises a magnetron 26 with a high voltage input circuit 28 and a filament 30.
  • the filament 30 is supplied by a filament transformer 32 through a low pass RF filter means 34 constructed in accordance with this invention.
  • the filter means 34 which is a distributed impedance filter is so illustrated.
  • each line 36 of the filament 30 employs a filter assembly such as that shown in FIG. 2.
  • a pin 22 of the assembly shown in FIG. 2 is connected between each line 36 and one terminal of the filament transformer 32.
  • ground as shown in FIG. 3 is established by the ground plane 24 as shown in FIG. 2.
  • An RF low pass filter for use in a high temperature environment comprising:
  • a dielectricv layer comprising glass characterized by low electrical leakage at ambient temperatures of 200C to 300C, wherein said substrate is in the form of a tube and said dielectric layer is carried directly by the exterior surface of said tube, said dielectric layer being characterized by a coefficient of thermal expansion which is less than the coefi'icient of thermal expansion for said substrate,
  • a microwave system for use in an ambient of high temperature comprising:
  • a distributed low pass RF filter means for feeding said high voltage through to said filament while preventing microwave energy of said magnetronx from being propogated back to the input of said filament which is less than the coefficient of thermal expantfansfol'mel'
  • Said Substrate is in the form of a tube and ment transformer inserted within the metal plated said dielectric layer is carried directly by the exteaxial Opening of said Substrate in electrical rior surface of said tube, said dielectric layer being 10 Pl g r n th

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Microwave Tubes (AREA)
  • Filters And Equalizers (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Glass Compositions (AREA)
  • Filtering Materials (AREA)
US00223624A 1972-02-04 1972-02-04 Rf filters with glass on a substrate Expired - Lifetime US3789263A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US22362472A 1972-02-04 1972-02-04

Publications (1)

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US3789263A true US3789263A (en) 1974-01-29

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US00223624A Expired - Lifetime US3789263A (en) 1972-02-04 1972-02-04 Rf filters with glass on a substrate

Country Status (8)

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US (1) US3789263A (US06235095-20010522-C00021.png)
JP (1) JPS5747565B2 (US06235095-20010522-C00021.png)
BR (1) BR7300765D0 (US06235095-20010522-C00021.png)
CA (1) CA983134A (US06235095-20010522-C00021.png)
GB (1) GB1413021A (US06235095-20010522-C00021.png)
HK (1) HK20879A (US06235095-20010522-C00021.png)
IT (1) IT1046682B (US06235095-20010522-C00021.png)
SE (1) SE387494B (US06235095-20010522-C00021.png)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4100463A (en) * 1975-11-05 1978-07-11 Hitachi, Ltd. Magnetron, power supply, and fan integral assembly
US4104561A (en) * 1975-11-28 1978-08-01 New Nippon Electric Co., Ltd. Magnetron operating circuit
US4164685A (en) * 1976-09-14 1979-08-14 Tokyo Shibaura Electric Co., Ltd. Magnetron device
EP0025367A1 (en) * 1979-08-31 1981-03-18 The Bendix Corporation Filter connector
US4652842A (en) * 1983-03-21 1987-03-24 Amp Incorporated Stamped and formed filter pin terminal having an aperture for preventing solder wicking
US4698605A (en) * 1982-11-04 1987-10-06 Murata Manufacturing Co., Ltd. Monolithic LC feed-through filter having a ferrite body with a re-oxidized capacitive layer
US4992060A (en) * 1989-06-28 1991-02-12 Greentree Technologies, Inc. Apparataus and method for reducing radio frequency noise
EP0583809A1 (en) * 1992-07-20 1994-02-23 General Motors Corporation Ferroelectric-ferromagnetic composite materials
US5382928A (en) * 1993-01-22 1995-01-17 The Whitaker Corporation RF filter having composite dielectric layer and method of manufacture
EP0690528A2 (en) 1994-06-27 1996-01-03 General Motors Corporation Filter elements having ferroelectric-ferromagnetic composite materials
US5604405A (en) * 1993-07-07 1997-02-18 Hitachi, Ltd. Magnetron with feed-through capacitor having a dielectric constant effecting a decrease in acoustic noise
US5838212A (en) * 1996-01-11 1998-11-17 Eev Limited High frequency transition arrangement
US6346865B1 (en) 1999-04-29 2002-02-12 Delphi Technologies, Inc. EMI/RFI filter including a ferroelectric/ferromagnetic composite
US9269797B2 (en) * 2011-04-27 2016-02-23 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of semiconductor device
CN107919518A (zh) * 2017-11-13 2018-04-17 西安电子工程研究所 基于旋磁型带状传输线的高重频宽谱高功率微波振荡器

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5978724U (ja) * 1982-11-18 1984-05-28 株式会社村田製作所 Ｌｃフイルタ
FI101329B (fi) * 1996-08-29 1998-05-29 Nokia Telecommunications Oy Menetelmä tukiaseman summausverkon virittämiseksi
FI101330B1 (fi) * 1996-08-29 1998-05-29 Nokia Telecommunications Oy Menetelmä tukiaseman summausverkon virittämiseksi

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2820720A (en) * 1954-09-15 1958-01-21 Hughes Aircraft Co Glass-bonded ferrite
US3425004A (en) * 1963-11-29 1969-01-28 Mc Donnell Douglas Corp Radio frequency energy attenuator
US3456151A (en) * 1966-07-27 1969-07-15 Gen Electric Crossed-field discharge device and coupler therefor and microwave circuits incorporating the same
US3588758A (en) * 1969-04-28 1971-06-28 Itt Electrical connector filter having dielectric and ferromagnetic tubes bonded together with conductive electrode layers and having nonintegral connecting spring

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2820720A (en) * 1954-09-15 1958-01-21 Hughes Aircraft Co Glass-bonded ferrite
US3425004A (en) * 1963-11-29 1969-01-28 Mc Donnell Douglas Corp Radio frequency energy attenuator
US3456151A (en) * 1966-07-27 1969-07-15 Gen Electric Crossed-field discharge device and coupler therefor and microwave circuits incorporating the same
US3588758A (en) * 1969-04-28 1971-06-28 Itt Electrical connector filter having dielectric and ferromagnetic tubes bonded together with conductive electrode layers and having nonintegral connecting spring

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4100463A (en) * 1975-11-05 1978-07-11 Hitachi, Ltd. Magnetron, power supply, and fan integral assembly
US4104561A (en) * 1975-11-28 1978-08-01 New Nippon Electric Co., Ltd. Magnetron operating circuit
US4164685A (en) * 1976-09-14 1979-08-14 Tokyo Shibaura Electric Co., Ltd. Magnetron device
EP0025367A1 (en) * 1979-08-31 1981-03-18 The Bendix Corporation Filter connector
US4275945A (en) * 1979-08-31 1981-06-30 The Bendix Corporation Filter connector with compound filter elements
US4698605A (en) * 1982-11-04 1987-10-06 Murata Manufacturing Co., Ltd. Monolithic LC feed-through filter having a ferrite body with a re-oxidized capacitive layer
US4652842A (en) * 1983-03-21 1987-03-24 Amp Incorporated Stamped and formed filter pin terminal having an aperture for preventing solder wicking
US4992060A (en) * 1989-06-28 1991-02-12 Greentree Technologies, Inc. Apparataus and method for reducing radio frequency noise
US5856770A (en) * 1992-07-20 1999-01-05 General Motors Corporation Filter with ferroelectric-ferromagnetic composite materials
EP0583809A1 (en) * 1992-07-20 1994-02-23 General Motors Corporation Ferroelectric-ferromagnetic composite materials
US5512196A (en) * 1992-07-20 1996-04-30 General Motors Corporation Ferroelectric-ferromagnetic composite materials
US5382928A (en) * 1993-01-22 1995-01-17 The Whitaker Corporation RF filter having composite dielectric layer and method of manufacture
US5604405A (en) * 1993-07-07 1997-02-18 Hitachi, Ltd. Magnetron with feed-through capacitor having a dielectric constant effecting a decrease in acoustic noise
US5497129A (en) * 1994-06-27 1996-03-05 General Motors Corporation Filter elements having ferroelectric-ferromagnetic composite materials
EP0690528A2 (en) 1994-06-27 1996-01-03 General Motors Corporation Filter elements having ferroelectric-ferromagnetic composite materials
US5838212A (en) * 1996-01-11 1998-11-17 Eev Limited High frequency transition arrangement
US6346865B1 (en) 1999-04-29 2002-02-12 Delphi Technologies, Inc. EMI/RFI filter including a ferroelectric/ferromagnetic composite
US9269797B2 (en) * 2011-04-27 2016-02-23 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of semiconductor device
US20160163544A1 (en) * 2011-04-27 2016-06-09 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of semiconductor device
US9543145B2 (en) * 2011-04-27 2017-01-10 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of semiconductor device
US9911767B2 (en) * 2011-04-27 2018-03-06 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of semiconductor device comprising oxide semiconductor
US10249651B2 (en) 2011-04-27 2019-04-02 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of semiconductor device
CN107919518A (zh) * 2017-11-13 2018-04-17 西安电子工程研究所 基于旋磁型带状传输线的高重频宽谱高功率微波振荡器

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Publication number Publication date
IT1046682B (it) 1980-07-31
GB1413021A (en) 1975-11-05
HK20879A (en) 1979-04-06
JPS5747565B2 (US06235095-20010522-C00021.png) 1982-10-09
CA983134A (en) 1976-02-03
BR7300765D0 (pt) 1973-09-20
AU5130273A (en) 1974-07-25
JPS4889646A (US06235095-20010522-C00021.png) 1973-11-22
SE387494B (sv) 1976-09-06

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