CN116994845A - Internal silica gel-coated piezoresistor and preparation method thereof - Google Patents

Internal silica gel-coated piezoresistor and preparation method thereof Download PDF

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Publication number
CN116994845A
CN116994845A CN202311030835.7A CN202311030835A CN116994845A CN 116994845 A CN116994845 A CN 116994845A CN 202311030835 A CN202311030835 A CN 202311030835A CN 116994845 A CN116994845 A CN 116994845A
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CN
China
Prior art keywords
silica gel
piezoresistor
coated
ceramic chip
chip
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Pending
Application number
CN202311030835.7A
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Chinese (zh)
Inventor
王鹏鹏
周荣林
袁海兵
朱莉
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Nanjing Xianzheng Electronics Co ltd
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Nanjing Xianzheng Electronics Co ltd
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Priority to CN202311030835.7A priority Critical patent/CN116994845A/en
Publication of CN116994845A publication Critical patent/CN116994845A/en
Pending legal-status Critical Current

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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C7/00Non-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
    • H01C7/10Non-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
    • H01C7/12Overvoltage protection resistors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C1/00Details
    • H01C1/02Housing; Enclosing; Embedding; Filling the housing or enclosure
    • H01C1/034Housing; Enclosing; Embedding; Filling the housing or enclosure the housing or enclosure being formed as coating or mould without outer sheath
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C1/00Details
    • H01C1/08Cooling, heating or ventilating arrangements
    • H01C1/084Cooling, heating or ventilating arrangements using self-cooling, e.g. fins, heat sinks
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C1/00Details
    • H01C1/14Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/142Terminals 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 coated on the resistive element
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C1/00Details
    • H01C1/14Terminals or tapping points or electrodes specially adapted for resistors; Arrangements of terminals or tapping points or electrodes on resistors
    • H01C1/144Terminals 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
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C17/00Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/006Apparatus or processes specially adapted for manufacturing resistors adapted for manufacturing resistor chips
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C17/00Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/02Apparatus or processes specially adapted for manufacturing resistors adapted for manufacturing resistors with envelope or housing
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C17/00Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/28Apparatus or processes specially adapted for manufacturing resistors adapted for applying terminals
    • H01C17/281Apparatus or processes specially adapted for manufacturing resistors adapted for applying terminals by thick film techniques
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01CRESISTORS
    • H01C17/00Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/30Apparatus or processes specially adapted for manufacturing resistors adapted for baking

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermistors And Varistors (AREA)

Abstract

The application discloses an internally-coated silica gel type piezoresistor and a preparation method thereof, and relates to the technical field of piezoresistor preparation. According to the application, the piezoresistor is welded and then internally coated with the silica gel, so that the insulation effect can be effectively achieved, the reduction of the electrical performance of the piezoresistor caused by carbonization of epoxy resin is prevented, meanwhile, the internally coated silica gel has the characteristics of strong heat conduction capability and insulation and voltage resistance, the lightning surge resistance of the resistor can be improved, the service life of the resistor is prolonged, and under the double-layer protection of the internally coated silica gel and the epoxy resin, the piezoresistor has a stable working environment in a circuit, and the hidden trouble that the whole circuit is burnt out due to failure breakdown of a chip is avoided.

Description

Internal silica gel-coated piezoresistor and preparation method thereof
Technical Field
The application relates to the technical field of piezoresistor preparation, in particular to an internally-coated silica gel type piezoresistor and a preparation method thereof.
Background
The piezoresistor is a voltage limiting type protection device. By utilizing the nonlinear characteristic of the piezoresistor, when the overvoltage occurs between two poles of the piezoresistor, the piezoresistor can clamp the voltage to a relatively fixed voltage value, so that the protection of a subsequent circuit is realized.
The common piezoresistor is a resistor body prepared by welding and encapsulating a chip, after the resistor is subjected to multiple lightning surge impacts in a circuit, the epoxy resin is carbonized gradually due to the high temperature generated by the piezoresistor, the leakage current of the resistor is gradually increased, a large amount of heat is generated during the working of the piezoresistor, and failure phenomena such as breakdown, burnout and the like are easy to occur.
Disclosure of Invention
(one) solving the technical problems
Aiming at the defects of the prior art, the application provides the internally coated silica gel piezoresistor and the preparation method thereof, which can solve the problems that after the conventional resistor is subjected to multiple lightning surge impacts in a circuit, the epoxy resin is carbonized gradually due to the high temperature generated by the piezoresistor, the leakage current of the resistor is increased gradually, a large amount of heat is generated during the working of the piezoresistor, the breakdown, the burnout and other failure phenomena are easy to occur, and the stability and the reliability of the electrical performance of the piezoresistor can be improved.
(II) technical scheme
In order to achieve the above purpose, the application is realized by the following technical scheme:
an internally coated silica gel type piezoresistor and a preparation method thereof, comprising
The ceramic chip, the lateral part of ceramic chip adheres to the silver electrode, just the surface of silver electrode is equipped with the tin soldering lug, the inside welding of tin soldering lug has the lead wire, the outside cladding of welding lead wire has epoxy, just epoxy is the chip welding back internal coating at ceramic chip surface, ceramic chip internal surface sets up the internal coating silica gel.
Preferably, the welding lead is a tinned copper steel covered wire, and the tin soldering sheet is a lead-free soldering tin material.
Preferably, the ceramic chip is in a disc structure, and the diameter of the ceramic chip is 10mm-25mm.
A silica gel-coated piezoresistor and a preparation method thereof, the preparation steps are as follows:
step one: preparing a ceramic chip, pulping and grinding metal oxide in a ball milling tank, spraying and granulating, and sintering after molding to obtain the ceramic chip;
step two: preparing a ceramic resistor chip, brushing silver on the outer part of the ceramic chip, then firing silver to form a silver electrode, and testing the electrical performance parameters such as voltage-sensitive voltage, leakage current, voltage ratio and the like of the resistor;
step three: preparing a piezoresistor, welding a lead on the surface of the ceramic resistor chip through a tin soldering lug, internally coating silica gel, and coating by using an epoxy resin encapsulation layer to form the piezoresistor;
step four: and testing the piezoresistor, marking the outer surface of the piezoresistor after encapsulation and solidification by using laser, spraying and printing specification and model, retesting the voltage-sensitive voltage, leakage current, voltage ratio and other electrical performance parameters of the tested resistor, and selecting the appearance and cutting pins.
Preferably, the metal oxide is prepared by firing one or more oxides of zinc oxide, bismuth trioxide, nickel oxide, cobalt oxide, chromium oxide, manganese carbonate, antimony trioxide and the like.
Preferably, the sintering temperature is 1020-1180 ℃.
Preferably, the silver electrode is prepared by screen printing molecular silver paste, and reducing at 560-600 ℃ to make the ceramic chip compatible with the molecular silver layer.
Preferably, the internal coating silica gel is a polymer silicone rubber composite material, and has good heat conduction performance, flame retardance, moisture resistance, insulation and pressure resistance.
Preferably, the internal coating silica gel mainly comprises silicone resin and solvent, and comprises the following components in percentage by mass: the content of the silicon resin is 40-50%, and the balance is solvent.
(III) beneficial effects
According to the application, the silica gel is internally coated after the piezoresistor is welded, so that the insulation effect can be effectively achieved, the reduction of the electrical performance of the piezoresistor caused by carbonization of epoxy resin is prevented, meanwhile, the internally coated silica gel has the characteristics of strong heat conduction capacity and insulation and voltage resistance, the lightning surge resistance of the resistor can be improved, the service life of the resistor is prolonged, the failure rate of the product is reduced, and the reliability and stability of the product are improved. Under the double-layer protection of the internal coating silica gel and the epoxy resin, the piezoresistor has a stable working environment in the circuit, and the hidden trouble that the whole circuit is burnt out due to the failure breakdown of the chip is avoided.
Drawings
The foregoing description is only an overview of the present application, and is intended to provide a better understanding of the present application, as it is embodied in the following description, with reference to the preferred embodiments of the present application and the accompanying drawings.
FIG. 1 is a half-sectional view of a silica gel-coated varistor according to the present application.
Legend description: 1. internally coating silica gel; 2. a silver electrode; 3. a tin soldering lug; 4. an epoxy resin; 5. a lead wire; 6. and a ceramic chip.
Detailed Description
According to the embodiment of the application, the problem of high-temperature heat dissipation in the prior art is solved by providing the internally coated silica gel type piezoresistor and the preparation method thereof, so that the piezoresistor has a stable working environment in a circuit under the double-layer protection of the internally coated silica gel and the epoxy resin, and the hidden trouble that the whole circuit is burnt out due to the failure breakdown of a chip is avoided.
Example 1
The technical scheme in the embodiment of the application aims to solve the problem of heat dissipation of the chip, and the overall thought is as follows:
aiming at the problems existing in the prior art, the application provides an internal coating silica gel type piezoresistor, which comprises
The ceramic chip 6, silver electrode 2 is attached to the lateral part of ceramic chip 6, just silver electrode 2's surface is equipped with tin soldering lug 3, tin soldering lug 3 is leadless soldering tin material, the inside welding of tin soldering lug 3 has lead 5, welded lead 5 is tinned copper steel wire.
The outside of the welding lead 5 is coated with epoxy resin 4, the epoxy resin 4 is internally coated on the outer surface of the ceramic chip 6 after chip welding, and the inner surface of the ceramic chip 6 is provided with internally coated silica gel 1. The ceramic chip 6 has a disc structure.
A silica gel-coated piezoresistor and a preparation method thereof, the preparation steps are as follows:
step one: preparing a ceramic chip 6, pulping and grinding metal oxide in a ball milling tank, spraying and granulating, and sintering after molding to obtain the ceramic chip 6;
step two: preparing a ceramic resistor chip, brushing silver on the outer part of the ceramic chip 6, then firing silver to form a silver electrode 2, and testing the electrical performance parameters of the resistor, such as voltage-sensitive voltage, leakage current, voltage ratio and the like;
step three: preparing a piezoresistor, welding a lead 5 on the surface of the ceramic resistor chip through a tin soldering lug 3, internally coating silica gel, and coating by using an epoxy resin encapsulation layer 4 to form the piezoresistor;
step four: and testing the piezoresistor, marking the outer surface of the piezoresistor after encapsulation and solidification by using laser, spraying and printing specification and model, retesting the voltage-sensitive voltage, leakage current, voltage ratio and other electrical performance parameters of the tested resistor, and selecting the appearance and cutting pins.
The metal oxide is prepared by firing one or more of zinc oxide, bismuth trioxide, nickel oxide, cobalt oxide, chromium oxide, manganese carbonate, antimony trioxide and the like, and the sintering temperature is 1020-1180 ℃.
And (3) after the silica gel 1 is coated on the inner surface of the welded ceramic chip, encapsulating the epoxy resin 4, and then preserving the heat for 1-2 hours at the temperature of 150-160 ℃ for curing to obtain the ceramic chip.
The silver electrode 2 is prepared by screen printing molecular silver paste, and reducing at 560-600 ℃ to make the ceramic chip 6 compatible with the molecular silver layer.
The internal coating silica gel 1 is made of a high molecular silicon rubber composite material, and the internal coating silica gel 1 has good heat conduction performance, flame retardance, moisture resistance, insulation and pressure resistance.
The internally coated silica gel 1 mainly comprises silicon resin and a solvent, and comprises the following components in percentage by mass: the content of the silicon resin is 40-50%, and the balance is solvent.
The diameter of the ceramic chip 6 is 10mm-25mm, the diameter of the piezoresistor is 10mm, the voltage-sensitive voltage is 562V, the green epoxy resin encapsulation layer 4 is encapsulated, no silica gel is coated after the chip is welded, and the rest structure is unchanged.
Example 2
The diameter of the piezoresistor is 10mm, the voltage-sensitive voltage is 562V, the green epoxy resin encapsulation layer 4 encapsulates the piezoresistor, the chip is internally coated with silica gel after being welded, and the rest structure is unchanged.
Example 3
The diameter of the piezoresistor is 14mm, the voltage-sensitive voltage is 685V, the green epoxy resin encapsulation layer 4 is encapsulated, no silica gel is coated after the chip is welded, and the rest structure is unchanged.
Example 4
The diameter of the piezoresistor is 14mm, the voltage-sensitive voltage is 685V, the green epoxy resin encapsulation layer 4 is encapsulated, the chip is internally coated with silica gel after being welded, and the rest structure is unchanged.
The die-bonding of example 1 and example 3 was performed without internally coating silica gel 1, and the die-bonding of example 2 and example 4 was performed with a varistor internally coated with silica gel 1, and the lightning current impulse performance test results are shown in the following table:
according to the table, the varistor with the silica gel is coated can be enabled to have small leakage current change after lightning current surge, and in lightning current surge performance, the varistor has better performance than the common varistor encapsulated by epoxy resin.
It is apparent that the above examples are only illustrative of the present application and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present application.

Claims (10)

1. An internally coated silica gel type piezoresistor is characterized in that: including ceramic chip (6), silver electrode (2) are attached to the lateral part of ceramic chip (6), just silver electrode (2)'s surface is equipped with tin soldering lug (3), tin soldering lug (3) inside welding has lead wire (5), the outside cladding of welding lead wire (5) has epoxy (4), just epoxy (4) are interior scribble at ceramic chip (6) surface after the chip welding, ceramic chip (6) internal surface sets up interior scribbles silica gel (1).
2. An internally coated silica gel varistor as claimed in claim 1, wherein: the ceramic chip (6) is of a disc structure, and the diameter of the ceramic chip (6) is 10mm-25mm.
3. An internally coated silica gel varistor as claimed in claim 1, wherein: the welding lead (5) is a tinned copper steel covered wire.
4. An internally coated silica gel varistor as claimed in claim 1, wherein: the tin soldering sheet (3) is made of lead-free tin soldering material.
5. The silica gel-coated varistor as claimed in claim 1, wherein the preparation method comprises the steps of:
step one: preparing a ceramic chip (6), pulping and grinding metal oxide in a ball milling tank, then spraying and granulating, and then sintering after molding to obtain the ceramic chip (6);
step two: preparing a ceramic resistor chip, brushing silver on the outer part of the ceramic chip (6), then firing silver to form a silver electrode (2), and testing the electrical performance parameters such as voltage-sensitive voltage, leakage current, voltage ratio and the like of the resistor;
step three: preparing a piezoresistor, welding a lead (5) on the surface of the ceramic resistor chip through a tin soldering lug (3), internally coating silica gel, and coating by using an epoxy resin encapsulation layer (4) to form the piezoresistor;
step four: and testing the piezoresistor, marking the outer surface of the piezoresistor after encapsulation and solidification by using laser, spraying and printing specification and model, retesting the voltage-sensitive voltage, leakage current, voltage ratio and other electrical performance parameters of the tested resistor, and selecting the appearance and cutting pins.
6. The silica gel-coated varistor of claim 5 and the method for making the same, wherein: the metal oxide is prepared by firing one or more of zinc oxide, bismuth trioxide, nickel oxide, cobalt oxide, chromium oxide, manganese carbonate, antimony trioxide and the like, and the sintering temperature is 1020-1180 ℃.
7. The silica gel-coated varistor of claim 6 and the method for making the same, wherein: and (3) after the silica gel (1) is coated on the welded ceramic chip, encapsulating the epoxy resin (4), and then preserving the heat for 1-2 hours at 150-160 ℃ to obtain the ceramic chip.
8. The silica gel-coated varistor of claim 2 and the method for making the same, wherein: the silver electrode (2) is prepared by screen printing molecular silver paste, and reducing at 560-600 ℃ to make the ceramic chip (6) compatible with the molecular silver layer.
9. The silica gel-coated varistor of claim 5 and the method for making the same, wherein: the inner coated silica gel (1) is a polymer silicon rubber composite material.
10. The silica gel-coated varistor of claim 9 and the method for making same, wherein: the internally coated silica gel (1) mainly comprises silicon resin and a solvent, and comprises the following components in percentage by mass: the content of the silicon resin is 40-50%, and the balance is solvent.
CN202311030835.7A 2023-08-16 2023-08-16 Internal silica gel-coated piezoresistor and preparation method thereof Pending CN116994845A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311030835.7A CN116994845A (en) 2023-08-16 2023-08-16 Internal silica gel-coated piezoresistor and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311030835.7A CN116994845A (en) 2023-08-16 2023-08-16 Internal silica gel-coated piezoresistor and preparation method thereof

Publications (1)

Publication Number Publication Date
CN116994845A true CN116994845A (en) 2023-11-03

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Family Applications (1)

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Country Status (1)

Country Link
CN (1) CN116994845A (en)

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