WO2022178763A1 - Surface mount metal oxide varistor device - Google Patents

Surface mount metal oxide varistor device Download PDF

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Publication number
WO2022178763A1
WO2022178763A1 PCT/CN2021/077912 CN2021077912W WO2022178763A1 WO 2022178763 A1 WO2022178763 A1 WO 2022178763A1 CN 2021077912 W CN2021077912 W CN 2021077912W WO 2022178763 A1 WO2022178763 A1 WO 2022178763A1
Authority
WO
WIPO (PCT)
Prior art keywords
mov
device body
leads
lead frame
contact tab
Prior art date
Application number
PCT/CN2021/077912
Other languages
English (en)
French (fr)
Inventor
Dongjian Song
Werner Johler
Liang Gu
Libing LU
Xiaolong GONG
Original Assignee
Dongguan Littelfuse Electronics Company Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Dongguan Littelfuse Electronics Company Limited filed Critical Dongguan Littelfuse Electronics Company Limited
Priority to EP21927203.6A priority Critical patent/EP4298649A1/en
Priority to JP2023548896A priority patent/JP2024507178A/ja
Priority to PCT/CN2021/077912 priority patent/WO2022178763A1/en
Priority to CN202180094665.1A priority patent/CN116888691A/zh
Publication of WO2022178763A1 publication Critical patent/WO2022178763A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/144—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors the terminals or tapping points being welded or soldered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/28—Apparatus or processes specially adapted for manufacturing resistors adapted for applying terminals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
    • H01C7/102—Varistor boundary, e.g. surface layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
    • H01C7/12—Overvoltage protection resistors
    • H01C7/126—Means for protecting against excessive pressure or for disconnecting in case of failure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/14—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/148—Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors the terminals embracing or surrounding the resistive element

Definitions

  • the present disclosure relates generally to the field of voltage suppression devices and relates more particularly to a surface mount metal oxide varistor device that is temperature resistant, space saving, and amenable to high speed manufacturing and installation processes.
  • MOVs Metal oxide varistors
  • a conventional MOV device includes a metal oxide ceramic chip (the MOV) having electrodes disposed on opposite sides thereof. Conducive wire leads may be connected (e.g., soldered) to the metal electrodes to facilitate electrical connection of the MOV device within a circuit.
  • the MOV, the metal electrodes, and portions of the leads that are connected to the electrodes are typically coated with epoxy to protect these components from environmental contaminants and to prevent interference with surrounding electrical devices.
  • MOV devices of the type described above are associated with several shortcomings.
  • the wire leads of a conventional MOV device are inserted into through holes in a printed circuit board (PCB) .
  • the wire leads must then be soldered to both the frontside and the backside of the PCB, making the installation procedure incompatible with pick and place processes necessary for achieving high speed, automated assembly.
  • conventional MOV devices stand quite tall on a PCB, which may necessitate an undesirably large form factor in a completed electronic device.
  • the protective epoxy coating of a conventional MOV device cannot withstand the high operating temperatures (e.g., up to 125 degrees Celsius) necessary for meeting the AEC-Q200 stress resistance standard.
  • MOV device amenable to installation using high speed, pick and place processes. It is further desirable to provide such an MOV device having a compact form factor compared to conventional MOV devices. It is further desirable to provide such an MOV device capable of withstanding high operating temperatures (e.g., up to 125 degrees Celsius) necessary for meeting the AEC-Q200 stress resistance standard. It is with respect to these and other considerations that the present improvements may be useful.
  • An exemplary embodiment of a metal oxide varistor (MOV) device in accordance with the present disclosure may include a MOV chip having first and second electrodes disposed on opposing side thereof, a first lead frame portion including a first contact tab electrically connected to the first electrode and a first lead contiguous with the first contact tab and extending away from the MOV chip for connecting the MOV device within a circuit, a second lead frame portion including a second contact tab electrically connected to the second electrode and a second lead contiguous with the second contact tab and extending away from the MOV chip for connecting the MOV device within a circuit, and a device body encasing the MOV chip, the first contact tab, the second contact tab, and portions of the first and second leads, wherein the first and second leads extend out of the device body and are bent into flat abutment with a bottom surface of the device body.
  • MOV metal oxide varistor
  • FIG. 1 Another exemplary embodiment of a MOV device in accordance with the present disclosure may include a MOV chip having first and second electrodes disposed on opposing side thereof, a first lead frame portion including a first contact tab electrically connected to the first electrode and a first lead contiguous with the first contact tab and extending away from the MOV chip for connecting the MOV device within a circuit, a second lead frame portion including a second contact tab electrically connected to the second electrode and a second lead contiguous with the second contact tab and extending away from the MOV chip for connecting the MOV device within a circuit and a plastic device body encasing the MOV chip, the first contact tab, the second contact tab, and portions of the first and second leads, wherein the first and second leads extend out of the device body and are bent into flat abutment with a bottom surface of the device body, with portions of the first and second leads disposed within complementary recesses formed in the bottom surface.
  • An exemplary embodiment of a method of manufacturing a metal oxide varistor (MOV) device in accordance with the present disclosure may include stamping first and second lead frame portions out of a sheet of metal, the first and second lead frame portions being “L” shaped and extending from respective first and second frame members, separating the first lead frame portion from the second lead frame portion, bending the first and second leads frame portions to define respective first and second contact tabs, arranging the first and second leads frame portions in a mirror image relationship with the first contact tab of the first lead frame portion disposed in a confronting, parallel relationship with the second contact tab of the second lead frame portion, placing a MOV chip between the first and second contact tabs and electrically connecting the first and second contact tabs to respective first and second electrodes of the MOV chip, overmolding a device body onto the MOV chip, the first and second contact tabs, and portions of first and second leads of the first and second lead frame portions, cutting the first and second leads away from the first and second frame members, and bending the first and second leads into flat a
  • FIG. 1A is a perspective top view illustrating a MOV device in accordance with an exemplary embodiment of the present disclosure
  • FIG. 1B is a perspective bottom view illustrating the MOV device shown in FIG. 1A;
  • FIG. 2A is a perspective top view illustrating the MOV device shown in FIG. 1A with the device body removed;
  • FIG. 2B is a bottom view illustrating the MOV device shown in FIG. 1A with the device body removed;
  • FIG. 3 is a flow diagram illustrating an exemplary method of manufacturing the MOV device shown in FIG. 1A;
  • FIGS. 4-8 are a series of view illustrating various processes performed in accordance with the manufacturing method set forth in FIG. 3.
  • MOV metal oxide varistor
  • FIGS. 1A and 1B perspective top and bottom views of an exemplary embodiment of a metal oxide varistor (MOV) device 10 (hereinafter “the device 10” ) in accordance with the present disclosure are shown.
  • the device 10 metal oxide varistor
  • terms such as “front, ” “rear, ” “top, ” “bottom, ” “up, ” “down, ” “above, ” “below, ” etc. may be used herein to describe the relative placement and orientation of various components of the device 10, each with respect to the geometry and orientation of the device 10 as it appears in FIGS. 1A and 1B.
  • Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.
  • the device 10 may include a plastic device body 12 having a generally monolithic outward appearance.
  • Electrically conductive first and second leads 14, 16 may extend from opposing sides (e.g., front and rear sides) of the device body 12 and may be folded or bent around an underside of the device body 12, with end portions of the first and second leads 14, 16 being disposed within complementary recesses 22, 24 formed in the bottom surface 26 of the device body 12.
  • bottom surfaces of the first and second leads 14, 16 may be substantially coplanar with the bottom surface 26.
  • the device 10 may include a MOV chip 28 having first and second electrodes 30, 32 disposed on opposite sides thereof. Only one side of the MOV chip 28 is visible in FIG. 2A, but it will be understood that the second electrode 32 on the opposing side of the MOV chip 28 that is not within view may be substantially identical to the first electrode 30.
  • the MOV chip 11 may be formed of any MOV composition known in the art, including, but not limited to, zinc oxide granules embedded in ceramic.
  • the first and second electrodes 30, 32 may be formed of any suitable electrically conductive material, including, but not limited to, aluminum, copper, aluminum covered with copper, silver, tin, nickel, etc.
  • the MOV chip 28 and the first and second electrodes 30, 32 are depicted as being circular or disc-shaped, but this is not critical. It is contemplated that one or more of the MOV chip 28 and the first and second electrodes 30, 32 may have a different shape, such as rectangular, triangular, irregular, etc. without departing from the scope of the present disclosure.
  • the device 10 may further include first and second lead frame portions 36, 38, of which the above described first and second leads 14, 16 are parts, respectively.
  • the first and second leads 14, 16 may be bent or folded to define a “C” shape that extends away from the MOV chip 28, out of the device body 12 and around a bottom of the device body 12 (see FIGS. 1A and 1B) .
  • the first and second lead frame portions 36, 38 may include first and second contact tabs 40, 42 that are contiguous with the first and second leads 14, 16.
  • the first and second contact tabs 40, 42 may be bent or folded to extend around opposing sides of the MOV chip 28 and are secured to the first and second electrodes 30, 32, respectively, such as with high temperature solder.
  • the present disclosure is not limited in this regard.
  • first and second contact tabs 40, 42 may be bent or folded to define respective first and second kinked portions 44, 46 located adjacent the edges of the MOV chip 28.
  • the first and second kinked portions 44, 46 increase the distance between the first and second contact tabs 40, 42 and the opposing first and second electrodes 30, 32 along the surfaces of the MOV chip 28 (i.e., relative to a configuration in which the first and second contact tabs 40, 42 are entirely planar and extend unkinked along the sides of the MOV chip 28 to the edges of the MOV chip 28) . This increase in distance mitigates the risk of flashover between the first and second contact tabs 40, 42 and the opposing first and second electrodes 30, 32.
  • the gaps between the first and second contact tabs 40, 42 and the respective, adjacent first and second electrodes 30, 32 may measure about 0.70 millimeters to about 0.90 millimeters, for example.
  • the present disclosure is not limited in this regard.
  • the MOV chip 28, first and second electrodes 30, 32, and the first and second contact tabs 40, 42 of the first and second lead frame portions 36, 38 may be entirely encased within the device body 12 (see FIG. 1A and 1B) , with the first and second leads 14, 16 extending out of, and around a bottom surface 26 of, the device body 12 as described above.
  • the device body 12 may be formed of heat-resistant polymer that provides a good humidity barrier and that has high flowability when melted (e.g., during molding) . Examples of such polymers include liquid-crystal polymers (LCPs) and polyphenylene sulfide (PPS) .
  • LCPs liquid-crystal polymers
  • PPS polyphenylene sulfide
  • the device 10 may have a substantially planar bottom surface 26, with the bottom surfaces of the first and second leads 14, 16 being substantially coplanar with the bottom surface 26.
  • the device 10 provides an advantage relative to conventional MOV devices in that the device 10 can be flatly disposed on a PCB using high speed pick and place processes, and the first and second leads 14, 16 can be soldered to a PCB (requiring soldering to the frontside of the PCB only) using reflow or wave soldering processes, for example.
  • the device 10 provides a further advantage in that it has a compact form factor (e.g., stands shorter on a PCB) compared to conventional MOV devices.
  • the device 10 provides a further advantage relative to conventional MOV devices in that the plastic device body 12 allows the device to withstand high operating temperatures (e.g., up to 125 degrees Celsius) necessary for meeting the AEC-Q200 stress resistance standard.
  • FIG. 3 a flow diagram illustrating an exemplary method for manufacturing the above-described MOV device 10 in accordance with the present disclosure is shown. The method will now be described in conjunction with the flow diagram shown in FIG. 3 as well as a series of views shown in FIGS. 4-8 illustrating various processes performed as part of the method.
  • first lead frame portions 36 1-4 and second lead frame portions 38 1-4 may be stamped or otherwise cut from a sheet of metal.
  • the first and second lead frame portions 36 1-4 , 38 1-4 may be “L” shaped and may define first and second leads 14 1-4 , 16 1-4 and first and second contact tabs 40 1-4 , 42 1-4 , respectively (as yet unbent in the manner described above) .
  • first and second lead frame portions 36 1-4 , 38 1-4 may extend from respective first and second frame members 50, 52 which may facilitate a continuous, reel-to-reel stamping process whereby large quantities of frame members (i.e., greater than the four pictured) may be rapidly a stamped from a continuous roll of sheet metal.
  • the first and second lead frame portions 36 1-4 , 38 1-4 may be separated from one another, and the first and second contact tabs 40 1-4 , 42 1-4 of each of the first and second lead frame portions 36 1-4 , 38 1-4 may be bent/folded into their final shape described above (only the first lead frame portions 36 1-4 are pictured in FIG. 5, but it will be understood that the second lead frame portions 38 1-4 are identical to the first lead frame portions 36 1-4 ) .
  • portions of the first and second contact tabs 40 1-4 , 42 1-4 proximate their corresponding first and second leads 14 1-4 , 16 1-4 may be bent to extend vertically upwardly, and portions of the first and second contact tabs 40 1-4 , 42 1-4 distal from their corresponding first and second leads 14 1-4 , 16 1-4 may be bent to extend horizontally away from their corresponding first and second frame members 50, 52, with respective first and second kinked portions 44 1-4 , 46 1-4 formed therein.
  • first and second lead frame portions 36 1-4 , 38 1-4 may include embossed ribs 39 1-4 (formed during the above-described stamping process) at junctures of the first and second leads 14 1-4 , 16 1- 4 and their respective first and second contact tabs 40 1-4 , 42 1-4 to provide the folds formed at such junctures with increased strength to withstand subsequent molding processes (described below) .
  • the first and second lead frame portions 36 1-4 , 38 1-4 may be arranged in a confronting, “mirror image” relationship, with the first contact tabs 40 1-4 of the first lead frame portions 36 1-4 disposed in a confronting, parallel relationship with the second contact tabs 42 1-4 of the second lead frame portions 38 1-4 .
  • MOV chips 28 1-4 may then be disposed between the confronting first and second contact tabs 40 1-4 , 42 1-4 , and the first and second contact tabs 40 1-4 , 42 1-4 may be soldered to the first and second electrodes 30 1-4 , 32 1-4 of the MOV chips 28 1-4 .
  • Each MOV chip 28 1-4 and its corresponding first and second contact tabs 40 1-4 , 42 1-4 are placed within a mold (not shown) , and the plastic device bodies 12 1-4 may be overmolded thereon, with the first and second leads 14 1-4 , 16 1-4 of each of the first and second lead frame portions 36 1-4 , 38 1-4 extending horizontally out of the device bodies 12 1-4 (and still attached to the respective first and second frame members 50, 52) .
  • the first and second leads 14 1-4 , 16 1-4 of each of the first and second lead frame portions 36 1-4 , 38 1-4 may be cut away from their respective first and second frame members 50, 52 and may be bent or folded around the undersides of their respective device bodies 12 1-4 and disposed within complementary recesses formed in the bottom surfaces of the device bodies 12 1-4 (e.g., as described above and as shown in FIG. 1B) to form the completed devices 10 1-4 .
  • recesses or slots 60 1-4 may be formed in the front and rear surfaces of the device bodies 12 1-4 directly above the areas where first and second leads 14 1-4 , 16 1-4 extend out of the device bodies 12 1-4 (only the slots 60 1-4 on the front surfaces of the device bodies 12 1-4 are visible in FIG. 8, but it will be understood that identical slots are formed in the rear surfaces of the device bodies 12 1-4 ) .
  • the slots 60 1-4 may have widths that are equal to or greater than the widths of the first and second leads 14 1-4 , 16 1-4 .
  • the slots 60 1-4 provide clearance above the first and second leads 14 1-4 , 16 1-4 so that, when the first and second leads 14 1-4 , 16 1-4 are bent or folded into their final configuration, the portions of the device bodies 12 1-4 directly above the first and second leads 14 1-4 , 16 1-4 are not subjected to stresses that could otherwise result in cracking of the device bodies 12 1-4 .

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Manufacturing & Machinery (AREA)
  • Thermistors And Varistors (AREA)
  • Details Of Resistors (AREA)
PCT/CN2021/077912 2021-02-25 2021-02-25 Surface mount metal oxide varistor device WO2022178763A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP21927203.6A EP4298649A1 (en) 2021-02-25 2021-02-25 Surface mount metal oxide varistor device
JP2023548896A JP2024507178A (ja) 2021-02-25 2021-02-25 表面実装金属酸化物バリスタデバイス
PCT/CN2021/077912 WO2022178763A1 (en) 2021-02-25 2021-02-25 Surface mount metal oxide varistor device
CN202180094665.1A CN116888691A (zh) 2021-02-25 2021-02-25 表面贴装金属氧化物变阻器器件

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2021/077912 WO2022178763A1 (en) 2021-02-25 2021-02-25 Surface mount metal oxide varistor device

Publications (1)

Publication Number Publication Date
WO2022178763A1 true WO2022178763A1 (en) 2022-09-01

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ID=83047621

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Application Number Title Priority Date Filing Date
PCT/CN2021/077912 WO2022178763A1 (en) 2021-02-25 2021-02-25 Surface mount metal oxide varistor device

Country Status (4)

Country Link
EP (1) EP4298649A1 (zh)
JP (1) JP2024507178A (zh)
CN (1) CN116888691A (zh)
WO (1) WO2022178763A1 (zh)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2718744Y (zh) * 2004-05-28 2005-08-17 广东南方宏明电子科技股份有限公司 片式压敏电阻器
CN103098150A (zh) * 2010-06-21 2013-05-08 兴亚株式会社 表面安装压敏电阻
CN203085305U (zh) * 2012-12-28 2013-07-24 深圳顺络电子股份有限公司 一种压敏电阻
CN208189573U (zh) * 2018-03-16 2018-12-04 山东晶导微电子股份有限公司 一种半导体元器件封装结构
US20200343051A1 (en) * 2019-04-25 2020-10-29 Avx Corporation Integrated Component Including a Capacitor and Discrete Varistor
CN111968811A (zh) * 2020-09-15 2020-11-20 兴勤（常州）电子有限公司 一种贴片式压敏电阻及其制造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2718744Y (zh) * 2004-05-28 2005-08-17 广东南方宏明电子科技股份有限公司 片式压敏电阻器
CN103098150A (zh) * 2010-06-21 2013-05-08 兴亚株式会社 表面安装压敏电阻
CN203085305U (zh) * 2012-12-28 2013-07-24 深圳顺络电子股份有限公司 一种压敏电阻
CN208189573U (zh) * 2018-03-16 2018-12-04 山东晶导微电子股份有限公司 一种半导体元器件封装结构
US20200343051A1 (en) * 2019-04-25 2020-10-29 Avx Corporation Integrated Component Including a Capacitor and Discrete Varistor
CN111968811A (zh) * 2020-09-15 2020-11-20 兴勤（常州）电子有限公司 一种贴片式压敏电阻及其制造方法

Also Published As

Publication number Publication date
JP2024507178A (ja) 2024-02-16
CN116888691A (zh) 2023-10-13
EP4298649A1 (en) 2024-01-03

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