TWI441202B - Low capacitance multilayer chip varistor and overvoltage protection layer being used within the same - Google Patents

Description

Low-capacitance laminated wafer varistor and overvoltage protection layer used therefor

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a low capacitance stacked type wafer varistor, and more particularly to a low capacitance layered wafer varistor having a capacitance value of less than 0.3 pF at 1 MHz and for suppressing overvoltage, endurance of electrostatic shock, and protection of electronic circuits.

As shown in FIG. 1, a varistor 10 for use in a high frequency range includes a ceramic body 11, a pair of surface electrodes 12a and 12b, a pair of terminal electrodes 13a and 13b, and an insulating layer 20. Wherein, the surface electrodes 12a and 12b are formed on the same plane of the outer layer or the inner layer of the ceramic body 11 by a thin film technique, and the end electrodes 13a and 13b are respectively covered on both ends of the ceramic body 11, And electrically connected to the surface electrodes 12a and 12b, respectively; moreover, the insulating layer 20 fills the gap 14 between the surface electrodes 12a and 12b.

The insulating layer 20 is an insulating material having an overvoltage protection characteristic, and its microscopic structure, as shown in FIG. 2, is a substrate of a polymer material (or polymer) 21 as an insulating material (matrix) 22, in the microstructure of the polymer substrate 22, a micron-sized conductor having a particle diameter of 0.1 to 100 μm and semiconductor fine particles 23 are uniformly dispersed therein by first dispersion, and are dispersed in a first-order dispersed micron-sized conductor or Between the semiconductor fine particles 23, a nano-conductor having a particle diameter of 1 to 100 nm and semiconductor fine particles 24 are dispersed therebetween by a second dispersion to reduce the micro-scale conductor and the semiconductor fine particles 23 and the nano-conductor and the semiconductor. The spacing between the particles 24.

The varistor 10 has a very low capacitance value of less than 0.3 pF at 1 MHz, and when subjected to an abnormal overvoltage, the micron-sized conductor and the semiconductor fine particles 23 in the polymer substrate 22 of the insulating layer 20 and the nano-scale The distance between the conductor and the semiconductor fine particles 24 is extremely small, and electrons are tunneled between the conductor and the semiconductor fine particles, and have excellent suppression of overvoltage and static electricity resistance, so that they can be used as a protective element in a high frequency line.

However, the varistor 10 has the disadvantage that the insulating layer 20 is composed of the polymer material 21, and the material is carbonized due to high heat. When the varistor 10 is used as a protection element for suppressing an overvoltage in a high frequency line, the polymer substrate 22 of the insulating layer 20 is often carbonized by the high heat generated by an electrostatic shock or a surge overvoltage, thereby causing The varistor 10 is electrically conductive and loses protection of the electronic circuit or component. Therefore, the varistor 10 has a short life of electrostatic shock resistance. If it is directly impacted by 8KV static electricity, it can only withstand 500 impacts at a time, and a failure will occur.

In addition, as shown in FIG. 1 and FIG. 3, the ceramic body 11 of the other varistor 15 is made of an overvoltage protection material having a microporous structure 19, and the microstructure thereof has a relatively high proportion of porosity, including 3 to 50% by weight. An inorganic glass composition and 50 to 97 wt% of semiconductor or conductor particles 16 having a particle diameter of more than 0.1 μm; wherein the surface of the semiconductor or conductor particles 16 is coated with an inorganic glass film 17, and the inorganic glass film 17 is Submicron or nano-sized semiconductor particles or conductor particles 18 having a secondary dispersion and having a particle size of less than 1 micron.

The disadvantage of such a ceramic body 15 is that the ceramic body 11 contains a high content. The semiconductor or conductor particles 16 are expensive, and because the microporous structure 19 is easily wetted, the varistor 10 is electrically conductive without a protective function, which is disadvantageous for use in a high-humidity environment.

The main object of the present invention is to provide an over-voltage protection material, which is applied to a porous ceramic material as a substrate, and is applied between positive and negative electrodes of a high-frequency electronic circuit, and has an overvoltage (or transient surge voltage) and a resistance of several thousand. More than 8KV electrostatic shock capability, the composition consists of 10~30 wt% porous ceramic substrate, 65~80 wt% micron-sized conductor with 0.1-100 μm particle size and semiconductor particles and 5~10 wt% particle size. a nano-conductor or a semiconductor microparticle of 1 to 100 nm; and the microstructure of the porous ceramic substrate is covered with fine openings, and the micro-scale conductor and the semiconductor microparticle are uniformly dispersed in a first-order dispersion in the structure of the porous ceramic substrate The nano-scale conductor and the semiconductor fine particles are dispersed in a two-stage dispersion between the fine openings and between the first-order dispersed micro-scale conductors or semiconductor fine particles.

The porous ceramic substrate of the overvoltage protection material may be selected from one or more of corundum sand, tantalum carbide, cordierite, alumina, zirconia or calcium silicate.

The micron-sized and nano-sized conductor particles of the overvoltage protection material may be selected from the group consisting of platinum (Pt), palladium (Pd), tungsten (W), gold (Au), aluminum (Al), silver (Ag), and nickel. One or more of (Ni), copper (Cu), or an alloy thereof.

The micron-sized and nano-sized semiconductor microparticles of the overvoltage protection material may be selected from the group consisting of zinc oxide, titanium oxide, tin oxide, antimony, bismuth, niobium carbide, bismuth-tellurium (Si-Ge) alloy, One of indium antimonide, gallium arsenide, indium phosphide, gallium phosphide, zinc sulfide, zinc selenide, zinc telluride, barium titanate or barium titanate.

Another object of the present invention is to provide a low-capacitance laminated wafer varistor with excellent electrostatic protection effect and surge suppression capability, which is suitable for use in a high-humidity environment or/and a high-frequency circuit, and has a capacitance value less than 1 MHz. 0.3 pF, comprising a ceramic body, a pair of opposing inner electrodes, a pair of terminal electrodes and an overvoltage protection layer, wherein the ceramic body has excellent compact structure and no microporous structure, so it is not easily damp; The opposite inner electrodes are disposed on the same plane of the inner layer of the ceramic body or on different planes staggered up and down, and are spaced apart from each other by a gap, and are formed by filling the gap with the voltage protection material of the present invention. The voltage protection layer has the capability of resisting high temperature, suppressing overvoltage and resisting 8KV electrostatic shock of several thousand times or more; the pair of end electrodes respectively covering the left and right end portions of the ceramic body, and corresponding thereto One of the internal electrodes constitutes an electrical connection.

In the low-capacitance laminated type wafer varistor of the present invention, since the over-voltage protective layer used is completely sealed and coated by the ceramic body excellent in compactness of the structure, the low-capacity laminated type wafer varistor of the present invention is high. No protection is lost in wet or / or high frequency circuits.

The ceramic body is made of a low dielectric material and has no microporous structure, and may be selected from the group consisting of silicate glass, strontium aluminate glass, borate glass, phosphate glass, lead phosphate glass, aluminum oxide or carbonization. One of the crucibles; the inner electrode of the ceramic body may be made of platinum (Pt), palladium (Pd), gold (Au), silver (Ag) or nickel (Ni).

The terminal electrode of the ceramic body may be made of silver (Ag), copper (Cu) or silver-palladium alloy.

Another object of the present invention is to provide an array type low capacitance varistor having the same structure as the low capacitance varistor, comprising a ceramic body, a pair of opposite inner electrodes, a pair of terminal electrodes, and an overvoltage protection layer. Wherein each pair of opposing inner electrodes of the ceramic body are disposed on the same plane of the inner layer of the ceramic body, and are arranged side by side with each other; each pair of opposing inner electrodes are spaced apart from each other by a gap, and the invention is used The voltage protection material fills the gap to form the overvoltage protection layer, and has the capability of resisting high temperature, suppressing overvoltage and resisting 8KV electrostatic shock of several thousand times or more; the pair of terminal electrodes respectively covering the ceramic The left and right end portions of the body are electrically connected to the corresponding side-by-side internal electrodes.

As shown in FIG. 4 and FIG. 5, the low-capacitance laminated wafer varistor (hereinafter referred to as a low-capacitance varistor) 30 of the present invention is produced by a multilayer technology and then sintered at a high temperature, and includes one. The ceramic body 31, a pair of opposing inner electrodes 32a and 32b, a pair of terminal electrodes 33a and 33b, and an overvoltage protection layer (or overvoltage protection material) 40.

The opposite inner electrodes 32a and 32b are arranged in two ways, one of which is arranged on the same plane on the same plane as the inner layer of the ceramic body 31, as shown in FIG. a gap 34; another arrangement, as shown in FIG. 5, is formed on the inner layer of the ceramic body 31, but the upper and lower staggered are not on the same plane, and are spaced apart from each other by a gap 35; the end electrode 33a and 33b respectively covering the left and right ends of the ceramic body 31, and electrically connecting with the inner electrodes 32a and 32b, respectively; and, the overvoltage protection layer 40 fills the inner electrodes 32a and 32b Between the gaps 34 and 35.

The ceramic body 31 is made of a low dielectric material and may be selected from the group consisting of silicate glass, strontium aluminate glass, borate glass, phosphate glass, lead phosphate glass, aluminum oxide or tantalum carbide. Moreover, the ceramic body 31 is excellent in compactness after high-temperature sintering, has no microporous structure, can withstand high heat generated by electrostatic shock or surge overvoltage, and has an undesired generation of stray capacitance in the circuit. The effect of suppression is suitable for use in high humidity environments or/and high frequency circuits.

The internal electrodes 32a and 32b may be metal materials such as platinum (Pt), palladium (Pd), gold (Au), silver (Ag), or nickel (Ni).

The terminal electrodes 33a and 33b may be metal materials such as silver (Ag), copper (Cu) or silver palladium alloy.

The overvoltage protection layer 40 is a porous insulating material with overvoltage protection characteristics, and the composition thereof comprises 10 to 30 wt% of porous ceramic material 41, 65 to 80 wt% of micron-sized conductors having a particle diameter of 0.1 to 100 μm and The semiconductor fine particles 44 and 5 to 10 wt% of nano-conductor or semiconductor fine particles 45 having a particle diameter of 1 to 100 nm; moreover, the voltage protective layer 40 is applied between positive and negative electrodes of an electronic circuit or an electronic component, and has suppression Transient surge voltage and the ability to withstand electrostatic shock.

The porous ceramic material 41 may be selected from one or more of corundum sand, tantalum carbide, cordierite, alumina, zirconia or calcium silicate, and has the characteristics of high temperature resistance, high pressure resistance, acid resistance, alkali resistance and resistance. Corrosion and long service life, especially after high temperature After sintering, its structure will have a high proportion of fine openings due to changes in thermal expansion and contraction.

The micron-sized conductor particles 44 and the nano-conductor particles 45 may be selected from the group consisting of platinum (Pt), palladium (Pd), tungsten (W), gold (Au), aluminum (Al), silver (Ag), and nickel (Ni). One or more of copper (Cu) or an alloy thereof.

The micron-sized semiconductor microparticles 44 and the nano-semiconductor microparticles 45 may be selected from the group consisting of zinc oxide, titanium oxide, tin oxide, antimony, bismuth, antimony carbide, antimony-tellurium (Si-Ge) alloy, indium antimonide, gallium arsenide. One of indium phosphide, gallium phosphide, zinc sulfide, zinc selenide, zinc telluride, barium titanate or barium titanate.

As shown in FIG. 6, the microstructure of the overvoltage protection layer 40 is a matrix 42 having a porous ceramic material 41 as an insulating material, and the porous ceramic substrate 42 has a high proportion of micro-opening in the structure of the porous ceramic substrate 42. The holes 43, and including the first dispersion of the micron-sized conductors and the semiconductor particles 44 are uniformly dispersed therein, and the secondary dispersion of the nano-scale conductors and the semiconductor particles 45 are dispersed in the first-order dispersed micro-scale conductors or semiconductors. Between the particles 44.

More importantly, the material properties of the porous ceramic substrate 42 of the overvoltage protection layer 40 do not undergo physical changes due to high heat, and thus can endure the high heat generated by electrostatic shock or surge overvoltage; The porous ceramic substrate 42 has a high proportion of finely dispersed micropores 43 and a high content of micron-sized conductors and semiconductor microparticles 44 uniformly dispersed therein, and has a high content of two-stage dispersed nano-scale conductors and The semiconductor fine particles 45 are uniformly dispersed between the fine openings 43 or between the fine openings 43 and the micro-scale conductors and the semiconductor fine particles 44. Especially, when The voltage protection layer 40 is applied between the positive and negative electrodes of the circuit, and is subjected to an abnormal overvoltage because of the microvias 43 in the structure, the microvias 43 and the nanoscale conductors and The spacing between the semiconductor particles 45 or between the nano-conductor and the semiconductor particles 45 is extremely small, which facilitates strong tunneling of electrons, so that the over-voltage protection layer 40 of the present invention has excellent suppression of overvoltage and Resistant to static electricity and long life.

As shown in FIG. 4 and FIG. 5, the low capacitance varistor 30 of the present invention is characterized in that the inner electrodes 32a and 32b on the left and right sides are arranged on the same plane of the inner layer of the ceramic body 31 which is excellent in density and is not easily damp. On the upper or upper and lower staggered planes, and the overvoltage protection layers 40 of the inner electrodes 32a and 32b and the gaps 34 and 35 filled between the inner electrodes 32a and 32b are received by the ceramic body 31 together. Completely sealed, this structure will allow the overvoltage protection layer 40 to withstand high heat and be completely unaffected by changes in the surrounding environment.

Therefore, the low-capacitance varistor 30 of the present invention has a very low capacitance characteristic, and has a capacitance value of less than 0.3 pF at 1 MHz, and particularly has an 8 kV electrostatic shock resistance of several thousand times or more, after thousands of electrostatic shocks, Maintaining the original function is ideal for protecting against overvoltage and suppressing electrostatic shock in high-humidity environments or/and high-frequency lines.

As shown in FIG. 7, another array type low capacitance varistor 50 of the present invention has the same material, structure and function as the low capacitance varistor 30, but will be disposed on the same plane of the inner layer of the ceramic body 31. The upper left and right inner electrodes 32a and 32b are modified by a pair of inner electrodes 32a and 32b into two or more pairs of inner electrodes side by side. 32a and 32b, and both use the overvoltage protection layer 40 to fill the gap 34 between each pair of inner electrodes 32a and 32b.

The effects of the present invention will be clarified by the following examples and comparative examples, but the scope of the invention is not limited to the scope of the examples.

Examples 1-3 and Comparative Examples 1-3

The overvoltage protection materials of Examples 1-3 and Comparative Examples 1-3 were prepared according to the composition of Table 1, and were respectively applied to the gaps between the internal electrodes 32a and 32b of the same-sized low capacitance varistor 30 having the structure shown in FIG. 34. Further, the ceramic body 31 of the low capacitance varistor 30 has a structure in which pores are not formed, and the overvoltage protection material used is completely sealed and coated.

During the test, the varistor of Examples 1-3 and Comparative Examples 1-3 were connected in parallel between the positive and negative electrodes in the same high-frequency circuit, and the measurement items included a breakdown voltage, a maximum clamp voltage, and a capacitance. The value of (Capacitor), and the breakdown voltage offset after 1000 times of electrostatic shock by 8KV, the results are shown in Table 2.

result

According to the test results of Examples 1-3 and Comparative Examples 1-3 of Table 2, the following conclusions can be obtained:

1. The breakdown voltage change (ΔV/V _1mA ) of the low capacitance varistor of Example 1-3 does not exceed 10% after 1000 times of electrostatic shock of 8 kV; and the breakdown voltage of the low capacitance varistor of Comparative Example 1-3 ( ΔV/V _1mA ) exceeds 10%.

This result confirms that the voltage protection material of the low capacitance varistor of Embodiment 1-3 is based on a porous ceramic material, has an electrostatic discharge resistant (ESD) impact capability, and can withstand an electrostatic shock or a transient surge voltage. High fever.

2. The low capacitance varistor characteristics of Embodiment 1-3, including a breakdown voltage of 200 to 800 V, a maximum clamping voltage of less than 150 V, a capacitance value of less than 0.3 pF at 1 MHz, and a breakdown voltage change after 1000 times of electrostatic shock of 8 KV (Δ) V/V _1mA ) does not exceed 10%.

In Examples 1-3, the low capacitance varistor characteristics of Examples 1-3 were relatively low in terms of breakdown voltage and maximum clamping voltage, and the variation of ΔV/V _{1 mA} did not exceed that of Comparative Examples 1-3. 10%, so the low capacitance varistor of Embodiment 1-3 is suitable for use as a protection element for suppressing transient surge voltage and electrostatic shock resistance in high frequency electronic circuits.

3. Example 3 Compared with Comparative Example 1, the difference between the voltage protection material is the use of a porous ceramic material or the use of a glass material as a substrate.

In the third embodiment, compared with the second comparative example, the voltage protective material of the comparative example 2 does not include the second-order dispersed nano-conductor and the semiconductor microparticle (hereinafter referred to as nanometer) except for the glass material. Grade particles).

According to the result of the comparison, the low capacitance varistor characteristic of Embodiment 3 is relatively low in terms of breakdown voltage and maximum clamp voltage. However, the low capacitance varistor of Comparative Example 2 has the worst characteristics.

This result confirms that the characteristics of the low capacitance varistor are related to the voltage protection material used, and the characteristics of the low capacitance varistor, the voltage protection material is preferably a porous ceramic material, and the glass material is inferior.

4. Compared with Comparative Example 3, Example 3 is only a difference in whether or not the porous ceramic material of the voltage protective material contains secondary dispersed nano-sized particles. However, the low capacitance varistor characteristic of Embodiment 3 is relatively low in terms of breakdown voltage and maximum clamping voltage.

This result confirms that the characteristics of the low capacitance varistor are related to whether or not the second-phase dispersed nano-sized particles are contained in the voltage-protecting material used, and according to the data of Examples 1-3, the porous ceramic material of the voltage-protecting material is The higher the content of the second-order dispersed nano-sized particles, the lower the breakdown voltage and the highest clamping voltage of the low-capacitance varistor, and the characteristics of the low-capacitance varistor are better.

10‧‧‧Resistor

11‧‧‧Ceramic body

12a, 12b‧‧‧ surface electrode

13a, 13b‧‧‧ terminal electrode

14‧‧‧ gap

15‧‧‧Resistor

16‧‧‧micron conductors or semiconductor particles

17‧‧‧Inorganic glass film

18‧‧‧Nano-scale conductors or semiconductor particles

19‧‧‧Porous structure

20‧‧‧Overvoltage protection materials

21‧‧‧ Polymer materials

22‧‧‧Substrate

23‧‧‧micron conductors or semiconductor particles

24‧‧‧Nano-level conductors or semiconductor particles

30‧‧‧Low capacitance laminated wafer varistor

31‧‧‧Ceramic body

32a‧‧‧ internal electrode

32b‧‧‧ internal electrode

33a‧‧‧ terminal electrode

33b‧‧‧ terminal electrode

34‧‧‧ gap

35‧‧‧ gap

40‧‧‧Overvoltage protection layer

41‧‧‧Porous ceramic materials

42‧‧‧Substrate

43‧‧‧Micro-opening

44‧‧‧micron conductor or semiconductor particles

45‧‧‧Nano-scale conductors or semiconductor particles

50‧‧‧Array varistor

Figure 1 is a schematic illustration of a varistor.

2 is a schematic view showing the microstructure of an overvoltage protection material used in the varistor of FIG. 1.

3 is a schematic view showing the microstructure of the ceramic body of the varistor of FIG. 1 in the A region.

4 is a partial cross-sectional view of the low capacitance varistor of the present invention, showing that the opposing inner electrodes are on the same plane with a gap therebetween.

5 is a partial cross-sectional view of the low capacitance varistor of the present invention, showing that the opposing inner electrodes are not on the same plane but are spaced apart from each other by a gap.

FIG. 6 is a schematic view showing the microstructure of the overvoltage protection material used in the varistor of FIG. 4 or 5.

Figure 7 is a partial cross-sectional view showing the array type low capacitance varistor of the present invention.

40‧‧‧Overvoltage protection layer

41‧‧‧Porous ceramic materials

42‧‧‧Substrate

43‧‧‧Micro-opening

44‧‧‧micron conductor or semiconductor particles

45‧‧‧Nano-scale conductors or semiconductor particles

Claims (7)

An over-voltage protection material, which is based on a porous ceramic material, is applied between positive and negative electrodes to suppress transient surge voltage and endure electrostatic shock, and is characterized in that it comprises 10~30wt% porous ceramic substrate and 65~80wt% particles. a micron-sized conductor or semiconductor microparticle having a diameter of 0.1 to 100 μm and 5 to 10 wt% of a nano-conductor or a semiconductor microparticle having a particle diameter of 1 to 100 nm; and the microstructure of the porous ceramic substrate is covered with fine openings The micron-sized conductor and the semiconductor microparticles are uniformly dispersed in the microstructure of the porous ceramic substrate in a first-order dispersion, and the nano-conductor and the semiconductor microparticles are dispersed in the second-order dispersion between the fine openings and the first-order dispersed micron-order Between conductors or semiconductor particles. The overvoltage protection material according to claim 1, wherein the porous ceramic substrate is one or more selected from the group consisting of corundum sand, tantalum carbide, cordierite, alumina, zirconia or calcium silicate. Composed of. The overvoltage protection material according to any one of claims 1 to 2, wherein the micron-sized and nano-sized conductor particles are selected from the group consisting of platinum (Pt), palladium (Pd), tungsten (W), and gold ( One or more of Au), aluminum (Al), silver (Ag), nickel (Ni), copper (Cu), or an alloy thereof. The overvoltage protection material according to any one of claims 1 to 2, wherein the micron-sized and nano-sized semiconductor microparticles are selected from the group consisting of zinc oxide, titanium oxide, tin oxide, antimony, bismuth, antimony carbide, antimony. - bismuth (Si-Ge) alloy, indium antimonide, gallium arsenide, indium phosphide, gallium phosphide, zinc sulfide, zinc selenide, zinc telluride, barium titanate or barium titanate. A low-capacitance laminated wafer varistor having a capacitance value of less than 0.3 pF at 1 MHz, comprising: a ceramic body, a structure having no micropores formed of a low dielectric material, and the low dielectric material selected One of self-borating glass, strontium aluminate glass, borate glass, phosphate glass, lead phosphate glass, aluminum oxide or tantalum carbide; one or more pairs of opposite inner electrodes, disposed on the ceramic body The inner layers are on the same plane or on the upper and lower staggered planes, and the opposite inner electrodes are spaced apart from each other by a gap; a pair of end electrodes are respectively covered on both ends of the ceramic body, and corresponding to each pair One of the electrodes constitutes an electrical connection; an overvoltage protection layer is made of the overvoltage protection material of claim 1 and fills the gap between each pair of internal electrodes of the ceramic body. The low capacitance laminated type wafer varistor according to claim 5, wherein the internal electrode is made of platinum (Pt), palladium (Pd), gold (Au), silver (Ag) or nickel (Ni). . The low-capacitance laminated type wafer varistor according to claim 5, wherein the terminal electrode is made of silver (Ag), copper (Cu) or silver-palladium alloy.