TWI781418B - Ceramic overvoltage protection device with low capacitance and improved durability and method of making the same - Google Patents

Abstract

The present invention provides an improved overvoltage protection element. The overvoltage protection device comprises at least one ESD protection coupler comprising discharge electrodes in a plane, a gap insulator between the discharge electrodes, an overvoltage protection of the discharge electrodes parallel to the plane An element, wherein the overvoltage protection element includes a conductor and a second material. The overvoltage protection element also includes a first insulator located between the discharge electrode and the overvoltage protection element.

Description

Ceramic overvoltage protection device with low capacitance and improved durability and method of manufacturing the same

This application is a continuation-in-part of co-pending U.S. Patent Application Serial No. 16/165,159, filed November 19, 2018, the contents of which are incorporated herein by reference.

The present invention relates to a ceramic overvoltage protection device that provides improved control of trigger voltage, has low leakage current and does not breakdown due to repeated overvoltage pulses.

In modern electronics, there is an ever-increasing need to protect semiconductors, integrated circuits, and other components from electrostatic discharge (ESD) and fast electronic transients. ESD can exceed 30kV, which is far beyond what the core processor can withstand. ESD is a major cause of failure in integrated circuits and is a particular problem with the miniaturization of electronic devices where it has proven difficult to reliably provide adequate protection.

The need for ESD protection has increased the available space in devices dedicated to ESD protection. Apart from the function of the device, the occupation of space is countered by the constant demand for miniaturization of components and devices. In addition to taking up space in the ESD protection devices on the die, they also limit the speed and amount of data that can be processed. Therefore, there is a need for off-chip protection, especially separate components that can provide ESD protection without slowing down processing speed, without taking up valuable real estate within the circuit design or device.

Multilayer ceramic capacitor (MLCC) devices have an established role in ESD protection. The higher capacitance levels of MLCCs absorb charge from ESD or transient events. Unfortunately, high capacitance can compromise signal integrity in high-speed data applications. If MLCC If the capacitance decreases, the ability to absorb ESD or transient events will decrease because the absorbed charge Q depends on the capacitance C and the voltage V depends on the relationship Q=CV. It can thus be seen that if the capacitance is reduced by 50%, the voltage the capacitor must withstand must be increased by 50% to maintain the same ability to absorb a Coulomb charge Q. In practice, it is impossible to increase the withstand voltage capability of a low-capacitance MLCC to such an extent without compromising its capability. Furthermore, when using a protection device such as a varistor, leakage current to ground can be a major drain on the standby time of a battery powered device when the device is not operating. Any parasitic losses on the battery are undesirable, so protection devices with high leakage current and high capacitance are less desirable.

To meet the demands of modern circuits, an ideal ESD protection device preferably has low capacitance and negligible leakage current to ground in its non-operating state. When exposed to elevated voltage or current due to an ESD event, an ESD protection device should respond quickly, for example within <1 ns, to transfer potentially harmful transient energy to ground through a low resistance path. After the ESD event subsides, the ESD protection device should return to its previous non-working state. Additionally, an ESD protection device should be able to withstand multiple ESD or transient events while reverting to its original non-operating mode pre-proximity capacitance and pre-proximity leakage current characteristics. Meeting all of these criteria has proven difficult, especially in high-voltage applications, because modern circuit designers lack suitable ESD protection.

This article provides an improved ESD protection device that meets the advanced needs of modern circuits.

The present invention relates to an improved overvoltage protection device and a method of forming the improved overvoltage protection device.

It is an object of the present invention to provide an overvoltage protection device with low capacitance, low leakage current and the ability to withstand many ESD pulses.

A particular feature of the present invention is the ability to manufacture the overvoltage protection device using standard manufacturing techniques for MLCC capacitors.

Another feature of the present invention is that it allows high ESD protection to be combined with low capacitance multilayer ceramic capacitors so that the combined device can protect against high transient voltages while preserving capacitance for signal filtering while only Take up the smallest available space.

As will be appreciated, these and other embodiments are provided in overvoltage protection devices. The overvoltage protection device comprises at least one ESD protection coupler, the ESD protection coupler comprises discharge electrodes in a plane, a gap insulator between the discharge electrodes, an overvoltage protection element parallel to the discharge electrodes of the plane, wherein the overvoltage The voltage protection element includes a conductor and a second material. The overvoltage protection element also includes a first insulator between the discharge electrode and the overvoltage protection element.

Another embodiment provides a method of forming an overvoltage protection device. The method comprises the steps of: producing on a first insulator precursor at least one first layer comprising a second insulator precursor and an overvoltage protection component precursor; forming at least one second layer on an internal insulator precursor , the internal insulator precursor includes a pair of discharge electrodes and a gap insulator precursor between the discharge electrodes; the at least one first layer is laminated on the at least one second layer, and the covering aligning the gap insulator precursor with the overvoltage protection element precursor to form a stack; and heating the stack to form a stack comprising: a discharge electrode on a plane; a gap an insulator between the discharge electrodes of the plane; an overvoltage protection element parallel to the discharge electrodes; and a first insulator between the discharge electrodes and the overvoltage protection element.

Yet another embodiment provides a dual function overvoltage protection device. The overvoltage protection device includes at least one ESD protection coupler, the ESD protection coupler includes discharge electrodes in a plane, a gap insulator between the discharge electrodes, overvoltage protection elements parallel to the discharge electrodes, and A first insulator between the electrode and the overvoltage protection element. The dual-function overvoltage protection device also includes a capacitive coupler.

10:ESD protection device

11: Dual function ESD device

12: Discharge electrode

14: Gap insulator

16:Overvoltage protection element

18: The first insulator

2:ESD protection coupler

20: Second insulator

22: External insulator

23: capacitor ceramic

24: Internal insulator

25: Internal electrode

26: External terminal

28: Second external terminal

30:Discharge gun

31: Floating electrode

32:ESD protection device

34: Sensitive components

36: High voltage pulse generator

38: Power supply capacitor

4: capacitive coupler

40: charging resistor

41: Floating Electrode Capacitive Coupler

42: switch

44: Discharge resistor

100: position

102, 102 ' : layers

104: layers

104A: Location

104B: location

105: position

106: position

108: position

110: position

112: position

114: position

T _C : separation distance

T _OVP : Separation distance

T _FLO : Separation distance

Fig. 1 is a schematic cross-sectional view of an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of an embodiment of the present invention.

Fig. 3 is an enlarged cross-sectional view of an embodiment of the present invention.

Fig. 4 is an enlarged cross-sectional view of an embodiment of the present invention.

Fig. 5 is a schematic top view of an embodiment of the present invention.

Fig. 6 is a flowchart of an embodiment of the present invention.

7 and 8 are graphs showing the advantages of the present invention.

9 and 10 are schematic circuit diagrams illustrating the advantages of the present invention.

The present invention relates to an improved electrostatic discharge (ESD) protection device that has low capacitance and low leakage current in the inactive state, has a fast response time when an ESD event occurs, and can withstand many ESD events without loss of capacitance, leakage current or functionality. More specifically, the invention relates to a layered structure comprising a separate insulator layer as a laminate between a discharge electrode and an overvoltage protection element. This structure provides optimization of the trigger voltage, which is the threshold voltage at which transient energy is transferred to ground potential. The invention also relates to an ESD protection device further comprising a capacitive coupler suitable for signal filtering below a threshold voltage beyond which transient energy is diverted to ground potential.

During normal operation, the ESD protection coupler of the ESD protection device is passive or does not provide any function for the circuit, so by design, the ESD protection coupler should exhibit low capacitance, so that the distortion of high-speed signals can be minimized. However, during an ESD event, the ESD protection coupler effectively acts as a switch, allowing excess voltage to spread to ground potential.

The invention will now be described with reference to the accompanying drawings which form an integral, non-limiting component of the invention. Throughout the specification, like elements will be numbered accordingly.

An embodiment of the present invention will be described below with reference to FIG. 1 , wherein the ESD protection coupler 2 is schematically shown in a cross-sectional view. In FIG. 1 , the discharge electrodes 12 are preferably coplanarly separated by a gap insulator 14 . A first insulator 18 extends on the discharge electrode in a planar manner, thereby forming a laminated structure. An overvoltage protection element 16 is separated from each discharge electrode by the first insulator 18 . A second insulator 20 preferably surrounds the overvoltage protection element at the layer containing the overvoltage protection element. In a preferred but non-limiting embodiment, for ease of manufacture, the gap insulator, the first insulator and the second insulator are the same material. The ESD protection coupler functions during a transient event by the overvoltage protection element conducting pulse energy between the discharge electrodes. In a transient state, it passes through the first insulator. In a particularly preferred embodiment, the width of the overvoltage protection element 16 is not greater than the width of the gap insulator 14 , so that the overlapping of the overvoltage protection element and the discharge electrode 12 is minimized.

The following will describe the embodiment of the present invention with reference to the cross-sectional schematic diagram shown in FIG. 2 . In FIG. 2 , an ESD protection device 10 includes a plurality of ESD protection couplers 2 arranged in a layered or stacked structure. An optional but preferred inner insulator 24 may be located between adjacent ESD protection couplers. An external insulator 22 is located on the outside of all ESD protection couplers. For ease of manufacture, the outer and inner insulators are preferably the same material made, but not limited to. Those skilled in the art will appreciate that the external terminals 26, which are in electrical contact with the discharge electrodes 12, allow the ESD protection device to be electrically connected to an electrical circuit.

In another embodiment of the present invention, the aforementioned ESD protection device can form a dual-function ESD protection device with a capacitive coupler. A capacitive coupler may consist of at least two stacked electrodes of opposite polarity, or a capacitive coupler may employ floating electrodes. When incorporating a capacitive coupler, it is desirable to minimize the overlap area between the discharge electrode and the overvoltage protection element to reduce stray capacitance, thereby maintaining a low capacitance for the combined components. For ease of manufacture, the first insulator and the dielectric of the capacitor element are the same material. In this case, the thickness of the dielectric separating the capacitor electrodes must exceed the thickness of the first insulator.

The embodiments of the present invention will be described below with reference to the schematic diagram of the expanded section shown in FIG. 3 . A dual function ESD device 11 is shown in FIG. 3 . The dual function ESD device comprises at most n ESD protection couplers 2, where n is the number of ESD protection couplers in the device. The figure shows at least m capacitive couplers 4, where m is the number of capacitive couplers in the dual function ESD device. The capacitive coupler comprises parallel internal electrodes 25 of alternating polarity, wherein adjacent internal electrodes terminate in different external terminals 26 and are separated by a capacitor ceramic 23 . The inner insulator 24 may preferably be located between adjacent ESD protection couplers 2 . Preferably, the capacitor ceramic 23 is in alternating layers between adjacent internal electrodes 25 such that each set of adjacent internal electrodes forms a capacitive coupling, so that the number of capacitive couplers acts as a single capacitor. For ease of manufacture, capacitor ceramic 23, outer insulator 22, inner insulator 24, gap insulator 14 and first insulator 18 are preferably the same material. When the first insulator and the capacitor ceramics use the same composition, it is preferable that the distance between the overvoltage protection element 16 and the discharge electrode 12 is represented by _TOVP , which is smaller than the distance between the adjacent internal electrodes 25. Separation distance T _C . The separation distance of the ESD protection coupler 2 is smaller than that of the capacitive coupler 4 , which can prevent the capacitive coupler from being subjected to permanent electrical breakdown when encountering an ESD event. More preferably, T _C is twice T _OVP .

The following will describe the embodiment of the present invention with reference to the schematic diagram of the expanded section shown in FIG. 4 . In FIG. 4 is shown a dual function ESD device 11 which is similar to the device shown and described in FIG. 3 . In FIG. 4 , the dual-function ESD device includes m floating electrode capacitive couplers 41 . The floating electrode capacitive coupler includes coplanar inner electrodes 25 of opposite polarity, each terminating in opposing outer terminals 26 . A floating electrode 31 is parallel to the coplanar inner electrode and is separated from the plane of the coplanar inner electrode by capacitor ceramic 23 . When the first insulator and the capacitor ceramic are of the same composition, preferably the spacing between the overvoltage protection element 16 and the discharge electrode 12, denoted T _OVP , is smaller than the spacing between the coplanar internal electrode 25 and the floating electrode T _FLO . The separation distance of the ESD protection coupler 2 is smaller than that of the capacitive coupler 41 , which can improve the temporary electrical breakdown capability of the ESD protection coupler before the capacitive coupler suffers permanent electrical breakdown.

Preferably, the ESD protection device has a capacitance of at least 0.1 to no more than 23,000 pF. When the ESD protection device further comprises at least one capacitive coupler, the ESD protection device preferably has a capacitance of at least 100 pF and more preferably at least 1000 pF. When the ESD protection device does not comprise a respective capacitive coupler, the capacitance of the ESD protection device is preferably not greater than 100 pF, preferably not greater than 10 pF, even more preferably not greater than 2 pF.

The ESD protection device may be a two-terminal device in which a single external terminal is in electrical contact with adjacent coplanar discharge electrodes, as shown in FIG. 2 . Alternatively, the overvoltage protection elements may be collectively or individually terminated and electrically contacted to the second external terminal to form a multi-terminal device, such as a four-terminal device, as shown in FIG. 5 , but not limited thereto. In FIG. 5 , the second external terminal 28 may be in electrical contact with the same ESD protection coupler, a separate ESD protection coupler or a capacitive coupler as described with respect to FIGS. 3 and 4 .

The number of ESD protection couplers in the ESD protection device is not particularly limited. For functionality, at least one ESD protection coupler is necessary, hundreds of are within the scope of the present invention. Beyond about 20 ESD protection couplers, the benefits do not justify the cost and manufacturing complexity associated with a large stackup. Below about 3 ESD protection couplers, there is not enough redundancy. Preferably, having about 3 to about 10 ESD protection couplers is preferred, this number being a balance between manufacturing efficiency, cost, cumulative device capacitance, and benefit.

The number of capacitive couplers in the dual-function ESD protection device is not particularly limited. For function at least one capacitive coupler is necessary, hundreds are within the scope of the invention. When the number of capacitive couplers exceeds about 100, the benefits do not justify the cost and manufacturing complexity associated with the large number of stacks. Below about 3 capacitive couplers, the resulting capacitance in the allotted space is insufficient. It is preferred to have about 10 to about 20 capacitive couplers, which number is a balance between manufacturing efficiency, cost, and effectiveness.

Incorporating an insulating material, preferably an insulating dielectric material, as a first insulator between the discharge electrode and the overvoltage protection element maintains an ineffective capacitance in passive mode to minimize signal distortion and low leakage current to the electrical connection status. The first insulating material is preferably sufficiently insulating to minimize leakage currents. Particularly preferably, the leakage current of the ESD protection coupler is not greater than 5000nA, more preferably not greater than 2000nA, even more preferably not greater than 1000nA, even more preferably not greater than 50nA, even more preferably not greater than 5nA, and most preferably Not greater than 1nA. Furthermore, the first insulator is preferably capable of withstanding the operating voltage without degradation, thereby allowing the ESD protection component to return to passive mode without degradation after the transient event subsides. Even after many ESD events, especially the first insulator has no degradation condition, which improves capacitance stability and leakage current stability.

Using conventional MLCC fabrication techniques, the discharge electrode and overvoltage protection element precursor layers can be deposited directly onto a carrier film of ceramic dielectric precursor material to fabricate an ESD protection device. These layers can then be stacked into aligned sheets, pressed and sintered to form a single ceramic monolithic component. In this way, the overvoltage protection element It is separated from the discharge electrode by an insulating material of predetermined thickness, so that its thickness and composition can be controlled by the choice of carrier film material. The ability to control the thickness of the first insulator, coupled with the ability to control the composition, predictably controls the trigger voltage. Alternatively, the insulator may be applied in liquid or film form to form an insulating film layer, such as a stack of polyimide or other insulators, preferably polymers.

The thickness of the first insulator, or the distance between the discharge electrode and the overvoltage protection element, denoted T _OVP in FIGS. 3 and 4 , can be much smaller than the typical electrode spacing in spark gap type ESD devices. Conventional spark gap type ESD devices typically have a spacing between electrodes of at least about 6 μm (micrometers), and may exceed 50 μm. For the ESD protection device of the present invention, the distance between the discharge electrode and the overvoltage protection element is preferably not greater than 10 μm, so that the 8kV pulse wave maintains the trigger voltage when it is transiently transferred to less than 5000V. A thickness of about 1 μm for the first insulator is suitable as an example of the present invention.

The trigger voltage is the voltage below which the capacitive coupler (if present) performs the filter capacitor function and the ESD protection coupler is passive. At or above the trigger voltage, the ESD protection coupler shunts excess current to ground potential. The trigger voltage depends on the composition and thickness of the first insulator and the composition of the overvoltage protection element. As the thickness of the first insulator increases, the trigger voltage increases with the given first insulator and overvoltage protection element. Those skilled in the art will understand that by initially preparing a series of multiple ESD protection devices with a first insulator thickness, and then conducting tests to determine the optimum first insulator thickness, the desired first insulator composition and overvoltage protection element can be obtained. required trigger voltage. The trigger voltage is preferably at least 20% higher than the working voltage designed by those skilled in the art for different applications.

With no direct contact between the discharge electrode and the overvoltage protection element, the insulation resistance is several orders of magnitude higher than that of an ESD device made of direct contact between the overvoltage protection material and the discharge electrode. Discrete insulator layers are used as a stack to help maintain low leakage current performance for repeated ESD pulses in non-active mode. The modular multi-layer nature also provides another Advantage, because many ESD protection couplers can be stacked to form the protection element of the assembly, thereby increasing the ability of the device to withstand multiple ESD pulses before performance degradation.

In another embodiment of the device, the discharge electrode layers shown may be stacked alternately to provide capacitive couplers within the assembly as described above. It should also be noted that it is preferable to use a dielectric with a higher dielectric constant ("K") than the dielectric constant of the spark gap element capacitor used between the terminals, as this can add capacitance to the component depending on the speed of signal transmission . By controlling the capacitance of the capacitive coupler, the ESD protection device can suppress certain noises at lower transmission speeds.

In order to keep the capacitance of the ESD protection coupler low, it is desirable to reduce the overlap area between the overvoltage protection element and the discharge electrode. This is because the first insulator is relatively thin. For the same reason, it is desirable for the insulator to have a low dielectric constant, preferably less than 100. This can be explained by applying the general capacitance equation to the discharge electrode coupling through the first insulator, where: C=K*K ₀ *A* _n /t where: C=capacitance; K=dielectric of the first insulator constant; K ₀ = dielectric constant of free space (8.854 x 10 ^-12 F/m); A = overlapping area of discharge electrode and overvoltage protection element; n = number of layers of discharge electrode and overvoltage protection element; and t = thickness of the first insulator. Therefore, at a given overlap, as the thickness of the first insulator decreases, the capacitance increases, which can be overcome by reducing the overlap area. The overlay protection element itself may comprise a material with a relatively high dielectric constant, such as barium titanate, in order to minimize the overlay area.

An advantageous characteristic of the ESD protection device of the present invention is the superior ability of the characteristics of the materials used in the device to function at high operating temperatures and voltages. can be prepared An ESD protection device capable of continuous operation at high voltage (eg 500V) and high temperature (eg 200°C).

The first insulator, the second insulator and the gap insulator are respectively selected from materials having a low dielectric constant, and preferably each individually or comprise insulating ceramics or glass. Low dielectric constant dielectrics are preferred, and preferably the dielectric constant of the insulating ceramic is no greater than 100, and preferably no greater than 50. COG dielectrics are particularly preferred. Particularly preferred materials for _the first insulator, second insulator, gap insulator, and capacitor ceramic include calcium zirconate, non-stoichiometric barium titanium oxides such as _{Ba2Ti9O20 ; BaTi4O9} ; containing _neodymium or Barium rare earth oxides, titanium dioxide doped with various additives, calcium titanate, strontium titanate, zinc magnesium titanate, zirconium tin titanate and combinations thereof. As is known to those skilled in the art, the materials used for the first insulator, second insulator, gap insulator and capacitor ceramic must be thermally compatible with the discharge electrode to avoid degradation of the discharge electrode during sintering of the ceramics.

The inner and outer insulators are not particularly limited because their materials can be selected based on cost and compatibility with other materials. In one embodiment, the inner and outer insulators are the same material as at least one of the first insulator, the second insulator layer or the gap insulator for ease of manufacture.

The overvoltage protection element comprises a conductor which is preferably selected from a metal and a second material which is not a conductor. The second material preferably includes at least one of ceramics, glass or semiconductors. Insulating materials reduce conductivity, thereby minimizing leakage currents in ESD protection devices. Where it is desired to minimize capacitance, the overvoltage protection element preferably does not overlap significantly with the discharge electrode. In some embodiments, the overvoltage protection element is porous. The overvoltage protection element may include at least one of La, Ni, Co, Cu, Zn, Ru, Ag, Pd, Pt, W, Fe or Bi. Particularly preferred insulating ceramics include barium titanate or tantalum nitride. To illustrate the invention, an overvoltage protection element consisting of 75% by volume of Ni in combination with 25% by volume of barium titanate is suitable. The metal content must be higher than 50% by volume and not more than 90% by volume. Below 50% by volume, the conductivity is insufficient to be used as an overvoltage protection element, Whereas, above 90% by volume, the electrical conductivity is too high to achieve sufficiently low leakage. Preferably, the metal content is at least 70% to no more than 80% by volume and the second material comprises at least 20% to 30% by volume.

The discharge electrodes and internal electrodes can be made of any noble or base metal, preferably a base metal that burns in air. Preferred base metals are selected from nickel, tungsten, molybdenum, aluminium, chromium, copper, palladium, silver or alloys thereof. Most preferably, the discharge electrode comprises nickel.

ESD protection devices can be manufactured in a manner similar to the manufacture of multilayer ceramic capacitors, which is well documented and well known to those skilled in the art, in which a large separation layer comprising a printed pattern of the active layer is laminated in alignment, by Pressed, diced, fired and terminated to form a monolithic component. In the present invention, the active layers are the overvoltage protection element, the discharge electrode, the internal electrode and the floating electrode. Those skilled in the art of MLCC fabrication will appreciate that the top and bottom of the device may be formed with capping layers of blank dielectric to form the external insulators described herein to insulate the components of the component from the external surfaces. External terminals can be plated and surface mounted components using conventional techniques and materials.

An embodiment of the present invention will be described above with reference to FIG. 6 , which is a flow chart showing the manufacturing process of the ESD protection device. In Fig. 6, a series of layers are prepared at positions 100 indicated. Layers 102 and 102 ' comprise a precursor to an outer insulator and are prepared according to standard fabrication procedures known in the art for ceramic layers in MLCC capacitors. Layer 104 is the layer representing the ESD protection coupler formed when sites 104A and 104B are brought together and sintered. In a preferred embodiment, at location 104A, a coating comprising the overvoltage protection element precursor and the second insulator precursor is formed on the first insulator precursor layer. At location 104B, a layer comprising a precursor to the discharge electrode and a gap insulator on the precursor to the inner insulator is formed. If capacitive couplers are to be included, alternating layers including internal electrodes on the ceramic dielectric precursor are formed at location 105 . A floating electrode can be formed by aligned lamination of alternating layers used to form internal electrodes and ceramic, or it can include different printed patterns on a ceramic dielectric precursor as is known in the art. These layers are stacked in alignment at position 106 so that the discharge electrode, insulator layer precursor and overvoltage protection element are aligned in the same manner as discussed and shown elsewhere herein as the precursor to the internal electrode to form Aligned stacks. When the precursor of the overvoltage protection element is aligned, the gap insulator is covered, as can be understood from FIGS. 1 and 2 . The aligned stack is pressurized and heated at location 108 to the extent necessary to bond the insulator precursors, thereby forming the insulator, and bond adjacent layers together to form the composite laminate. The composite laminate is diced at station 110 to provide isolated ESD protection device precursors, which are then heat treated at station 112 . Finishing steps are performed on the ESD protection device precursor at location 114, including adding external terminals, capping if required, to form the ESD protection device, which may also include testing and packaging.

example

A series of 0603 EIA size ESD protection devices were produced using a Class I COG dielectric mainly composed of calcium zirconate with a dielectric constant of approximately 32 as gap insulator, primary insulator, secondary insulator, inner insulator and outer insulator. ESD protection devices were fabricated with different thicknesses of the first insulator. The overvoltage protection component mainly includes nickel titanate and barium titanate with a volume ratio of 3:1. The overvoltage protection element is made with 3 or 10 pairs of coplanar discharge electrodes, each pair having an overvoltage protection element with a discharge electrode separated by a first insulator. The overvoltage protection element is co-fired inside the device. According to the test procedure IEC 61000-4-2 of the International Electrotechnical Commission, an 8kV ESD pulse wave is applied to the ESD protection device, and the response to the pulse wave is analyzed. A typical test setup includes a Noiseken ESS S3011/GT30R ESD simulator (150pF 330 ohms combined) and a Keysight MSOS 804A high-definition oscilloscope with appropriate high frequency bandwidth attenuation.

ESD protection devices with 3 pairs and 10 pairs of nickel-based discharge electrodes with a thickness of 9 μm were prepared and evaluated. As shown in Table 1, an ESD protection device with 10 protection layers will trigger The voltage drops to about 20%, while the leakage current remains below 1nA when using 3 pairs of discharge electrodes. In addition, increasing the number of ESD protection couplings can reduce the trigger voltage from 1.7kV to 1.3kV in 1000 8kV pulses.

Figure 7 shows the response voltage versus time for an 8kV ESD pulse. In addition to reducing the peak voltage, parts with additional ESD protection coupling have better robustness in terms of voltage response after 1000 repeated 8kV ESD pulses, as shown in Figure 8, which graphically represents 1000 8kV ESD pulses Average voltage vs. time after an ESD pulse.

As mentioned above, it is desirable to achieve a low trigger voltage while maintaining stability and continuous low leakage current after exposure to multiple pulses. To test the effectiveness of the first insulator, an ESD protection device with three pairs of nickel discharge electrodes having different thicknesses of the first insulator was fabricated.

In another example, a series of 0603 EIA sizes were produced using a Class I COG dielectric consisting primarily of calcium zirconate with a dielectric constant of approximately 32 as the gap insulator, first insulator, second insulator, inner insulator, and outer insulator. similar ESD protection devices. ESD protection devices were fabricated with different thicknesses of the first insulator. Manufacture of a set of ESD protection devices consisting of an overvoltage element mainly consisting of nickel and titanate in a volume ratio of 3:1 and an overvoltage element consisting mainly of nickel and tantalum nitride in a volume ratio of 3:1 Build another set of ESD protection. The overvoltage protection element is co-fired inside the device. According to the test procedure IEC 61000-4-2 of the International Electrotechnical Commission, an 8kV ESD pulse wave was applied to the five ESD protection devices of each structure, and the response to the pulse wave was analyzed. A typical test setup includes a Noiseken ESS S3011/GT30R ESD simulator (150pF 330 ohms combined) and a Keysight MSOS 804A high-definition oscilloscope with appropriate high frequency bandwidth attenuation.

As shown in Table 2, increasing the thickness of the first insulator can reduce the leakage current after 1000 8kV pulses. It can also be seen from Table 2 that when tantalum nitride is used as the second material in the overvoltage protection element, when the trigger voltage is maintained, the leakage current is still very small after 1000 pulses.

To determine the ability of an ESD protection device to protect sensitive electronic components such as integrated circuits (ICs) from high-voltage ESD pulses, a test circuit was designed in which the ESD protection device and sensitive components were mounted in a parallel circuit configuration and subjected to ESD pulse. The ESD pulse generator used for the test is NoiseKen ESS-S3011A, which has a GT-30RA discharge gun and is configured to generate the ESD current pulse described in the EIC 61000-4-2 specification. The ESD pulse generator has a 150pF supply capacitor, a 1M ohm charging resistor and a 330 ohm discharging resistor. Fig. 9 is a schematic circuit diagram.

In FIG. 9 , an ESD discharge gun 30 provides pulses to an ESD protection device 32 connected in parallel with a sensitive component 34 . In FIG. 10 , a high voltage pulse generator 36 charges a power supply capacitor 38 through a charging resistor 40 , and a switch 42 is closed during the charging cycle and opened during the test pulse. After charging is complete, the switch opens during the charge cycle and closes as a test pulse, discharging the capacitor through the discharge resistor 44 and applying a pulse to the ESD protection device 32 and sensitive components 34 . An ESD discharge gun typically includes a high voltage pulse generator 36 , a power supply capacitor 38 , a charging resistor 40 and a switch 42 as integrated devices.

To perform the test, the supply capacitor in the ESD gun is charged to this test voltage and then discharged through the discharge resistor into the test circuit. The voltage between the ESD protection device and sensitive test components increases until the ESD protection device trigger voltage is reached, at which point the ESD protection device shunts the excess voltage to ground, protecting sensitive components from damage. Sensitive components can be damaged by the voltage pulse if the ESD protection device's voltage is higher than the voltage capability of the sensitive component, or if it fails to shunt enough current to ground.

An ESD protection device consisting of an overvoltage protection element made of barium titanate and another containing tantalum nitride as a second material was evaluated using the test circuit shown in Figure 9 to determine that the ESD protection device can protect sensitive components from 8kV ESD The ability of pulse influence. The sensitive components chosen for testing were two EIA 0603 C0G type MLCCs with Arranged in series, when the ESD discharge gun is charged to 2000V, it will fail after about 100 ESD pulses. Identify the failure of sensitive components by measuring the insulation resistance after a series of ESD pulses. Typically, the insulation resistance of the sensitive components used is greater than 100G ohms. It is determined that the damaged capacitor is a capacitor with an insulation resistance of less than 100M ohms. Additionally, two commercially available ESD protection components were tested for comparison.

Table 3 lists test results demonstrating the ability of ESD protection components to protect sensitive components from damage. Each test contains samples of five components. It can be seen from Table 3 that, compared with commercially available ESD protection components, the ESD protection components manufactured using the ceramic material and process described in the present invention can provide excellent ESD pulse protection capability.

The present invention has been described with reference to preferred embodiments, but is not limited thereto. Those skilled in the art will recognize other embodiments and modifications within the scope of the invention not specifically described herein but more particularly set forth in the appended claims.

12: Discharge electrode

14: Gap insulator

16:Overvoltage protection element

18: The first insulator

2:ESD protection coupler

20: Second insulator

Claims (79)

A ceramic overvoltage protection device with low capacitance and improved durability, comprising: at least one electrostatic discharge (ESD) protection coupler, comprising: a planar discharge electrode located on a plane; a planar gap insulator located on the Between the discharge electrodes and on the plane of the discharge electrodes; an overvoltage protection element parallel to the discharge electrodes of the plane, wherein the overvoltage protection element includes a conductor and a second material; and a first An insulator positioned between the discharge electrode and the overvoltage protection element, wherein at least one of the first insulator or the gap insulator has a dielectric constant less than 100. Ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein the ratio of the conductor to the second material of the overvoltage protection element is at least 50% by volume to no more than 90% by volume %. According to the ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein the conductor system is selected from La, Ni, Co, Cu, Zn, Ru, Ag, Pd, Pt, W, A group consisting of Fe or Bi. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein the second material is selected from the group consisting of ceramic, glass and semiconductor. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 4, wherein the ceramic is selected from the group consisting of barium titanate and tantalum nitride. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein at least one of the first insulator or the gap insulator has a dielectric constant less than 100. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein the thickness of the first insulator is at least 1 μm to no more than 10 μm. A ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein said first insulation system is selected from the group consisting of calcium zirconate, non-stoichiometric barium titanium oxide; barium rare earth oxide; Titanium dioxide; the group consisting of calcium titanate, strontium titanate, zinc magnesium titanate, zirconium tin titanate and combinations thereof. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 8, wherein the non-stoichiometric barium titanium oxide is selected from Ba ₂ Ti ₉ O ₂₀ or BaTi ₄ O ₉ . 8. The ceramic overvoltage protection device with low capacitance and improved durability as claimed in claim 8, wherein said barium rare earth oxide comprises neodymium or nickel. The ceramic overvoltage protection device having low capacitance and improved durability according to claim 8, wherein the titanium dioxide is doped titanium dioxide. A ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, comprising no more than 20 electrostatic discharge (ESD) protection couplers. A ceramic overvoltage protection device with low capacitance and improved durability according to claim 12, comprising 3 to 10 of said electrostatic discharge (ESD) protection couplers. A ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, comprising an inner second insulator between adjacent said electrostatic discharge (ESD) protection couplers. According to the ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, wherein the discharge electrode comprises nickel, tungsten, molybdenum, aluminum, chromium, copper, palladium, silver, or an alloy thereof At least one metal in the group consisting of. The ceramic overvoltage protection device having low capacitance and improved durability according to claim 15, wherein the discharge electrode comprises nickel. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, further comprising external terminals. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, further comprising at least one capacitive coupler. The ceramic overvoltage protection device having low capacitance and improved durability according to claim 18, wherein said capacitive coupler comprises a floating electrode. According to the ceramic overvoltage protection device with low capacitance and improved durability of claim 18, the capacitive coupler has a capacitance of at least 1000 pF and no more than 23,000 pF. According to the ceramic overvoltage protection device with low capacitance and improved durability of claim 18, the capacitive coupler has a capacitance of at least 0.1 pF and no more than 23,000 pF. According to the ceramic overvoltage protection device with low capacitance and improved durability of claim 21, the capacitive coupler has a capacitance of at least 0.1 pF to no more than 100 pF. According to the ceramic overvoltage protection device with low capacitance and improved durability of claim 22, the capacitive coupler has a capacitance no greater than 10 pF. According to the ceramic overvoltage protection device with low capacitance and improved durability of claim 23, the capacitive coupler has a capacitance no greater than 2pF. The ceramic overvoltage protection device with low capacitance and improved durability according to claim 1, which has a trigger voltage at least 20% higher than an operating voltage. According to claim 1, the ceramic overvoltage protection device with low capacitance and improved durability has a leakage current not greater than 5000 nA. According to claim 26, the ceramic overvoltage protection device with low capacitance and improved durability has a leakage current not greater than 1000 nA. According to claim 27, the ceramic overvoltage protection device with low capacitance and improved durability has a leakage current not greater than 50 nA. According to claim 28, the ceramic overvoltage protection device with low capacitance and improved durability has a leakage current not greater than 5nA. According to claim 29, the ceramic overvoltage protection device with low capacitance and improved durability has a leakage current not greater than 1 nA. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability, comprising: manufacturing at least a first insulator precursor comprising a second insulator precursor and an overvoltage protection element precursor on a planar first insulator precursor one layer; forming at least one second layer on an inner insulator precursor comprising a pair of discharge electrodes and a planar gap insulator precursor between said discharge electrodes; will comprise said at least one laminating a first layer on said at least one second layer, and aligning a gap insulator precursor overlying said plane with said overvoltage protection element precursor to form a stack; and heating said stack to form a laminated structure comprising the following components: discharge electrodes on a plane; a plane gap insulator positioned between said discharge electrodes on said plane; an overvoltage protection element parallel to said discharge electrodes; and a planar first insulator located between the discharge electrode and the overvoltage protection element, wherein the dielectric constant of the first insulator is less than 100. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, wherein the overvoltage protection element comprises a conductor and a second material. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 32, wherein the ratio of the conductor to the second material of the overvoltage protection element is at least 50% by volume to no More than 90% by volume. According to the method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 32, wherein the conductor system is selected from the group consisting of La, Ni, Co, Cu, Zn, Ru, Ag, Pd, Pt , a group consisting of W, Fe or Bi. According to the method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability as claimed in claim 32, the second material is selected from the group consisting of ceramics, glass and semiconductors. The method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 35, wherein the ceramic is selected from the group consisting of barium titanate and tantalum nitride. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31 , wherein the dielectric constant is less than 50. The method of forming a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, wherein the thickness of the first insulator is at least 1 μm to no more than 10 μm. The method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, wherein said first insulator comprises an insulating ceramic. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 39, wherein said first insulation system is selected from the group consisting of calcium zirconate, non-stoichiometric barium titanium oxide; barium rare earth Oxides; Titanium dioxide; Calcium titanate, strontium titanate, zinc magnesium titanate, zirconium tin titanate and the group consisting of combinations thereof. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 40, wherein the non-stoichiometric barium titanium oxide is selected from Ba ₂ Ti ₉ O ₂₀ or BaTi ₄ O ₉ . A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 40, wherein the barium rare earth oxide comprises neodymium or nickel. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 40, wherein the titanium dioxide is doped titanium dioxide. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, comprising forming a stack comprising no more than 20 of said first layer and said second layer. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 44, comprising forming a stack comprising 3 to 10 of said first layer and said second layer. According to the method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, wherein the discharge electrode comprises a material selected from the group consisting of nickel, tungsten, molybdenum, aluminum, chromium, copper, palladium, silver, or at least one metal from the group consisting of alloys thereof. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 46, wherein the discharge electrode comprises nickel. The method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, further comprising forming external terminals. The method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 31, further comprising forming alternating layers of a capacitive coupler precursor prior to said forming said stack. A method of manufacturing a ceramic overvoltage protection device having low capacitance and improved durability according to claim 49, wherein said step of forming said laminate further comprises covering said capacitive coupler precursor prior to said heating Alternate layers. A method of manufacturing a ceramic overvoltage protection device with low capacitance and improved durability according to claim 49, wherein said alternating layers of said capacitive coupler comprise at least one floating electrode precursor. A ceramic overvoltage protection device with dual function low capacitance and improved durability comprising: at least one electrostatic discharge (ESD) protection coupler comprising: discharge electrodes in a plane; a gap insulator in a plane between said discharge electrodes in said plane; an overvoltage protection element parallel to said plane the discharge electrode; and a planar first insulator positioned between the discharge electrode and the overvoltage protection element, wherein at least one of the first insulator or the gap insulator has a dielectric constant less than 100; and a capacitive coupler. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52, wherein said overvoltage protection element comprises a conductor and a second material. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 53, wherein the ratio of the conductor to the second material of the overvoltage protection element is at least 50% by volume and not greater than 90% by volume. According to the ceramic overvoltage protection device with dual functions, low capacitance and improved durability according to claim 53, wherein the conductor system is selected from La, Ni, Co, Cu, Zn, Ru, Ag, Pd, Pt, A group consisting of W, Fe or Bi. According to claim 53, the ceramic overvoltage protection device with dual function, low capacitance and improved durability, wherein said second material is selected from the group consisting of ceramic, glass and semiconductor. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 56, wherein said ceramic is selected from the group consisting of barium titanate and tantalum nitride. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52, wherein said dielectric constant is less than 50. The ceramic overvoltage protection device with dual function low capacitance and improved durability according to claim 51, wherein the thickness of the first insulator is at least 1 μm to no more than 10 μm. According to the ceramic overvoltage protection device with dual function low capacitance and improved durability according to claim 52, wherein said first insulation system is selected from the group consisting of calcium zirconate, non-stoichiometric barium titanium oxide; barium rare earth oxide Titanium dioxide; calcium titanate, strontium titanate, zinc magnesium titanate, zirconium tin titanate and a group consisting of combinations thereof. A ceramic overvoltage protection device with dual function low capacitance and improved durability according to claim 60, wherein said non _- stoichiometric barium titanium _oxide is selected _{from Ba2Ti9O20} or _BaTi4O9 . 61. The ceramic overvoltage protection device having dual function low capacitance and improved durability as recited in claim 60, wherein said barium rare earth oxide comprises neodymium or nickel. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 60, wherein said titanium dioxide is doped titanium dioxide. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52 comprising no more than 20 electrostatic discharge (ESD) protection couplers. A ceramic overvoltage protection device with dual function low capacitance and improved durability according to claim 64 comprising 3 to 10 of said electrostatic discharge (ESD) protection couplers. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52, comprising an inner second insulator between adjacent said electrostatic discharge (ESD) protection couplers. According to claim 52, a ceramic overvoltage protection device with dual function, low capacitance and improved durability, wherein said discharge electrode comprises a material selected from the group consisting of nickel, tungsten, molybdenum, aluminum, chromium, copper, palladium, silver, or At least one metal from the group consisting of its alloys. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 67, wherein said discharge electrode comprises nickel. The ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52, further comprising external terminals. The ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52, wherein said capacitive coupler comprises a floating electrode. A ceramic overvoltage protection device with dual function low capacitance and improved durability according to claim 52 having a trigger voltage at least 20% higher than an operating voltage. According to the ceramic overvoltage protection device with dual function low capacitance and improved durability of claim 52, said capacitive coupler has a capacitance of at least 100 pF to no more than 23,000 pF. According to the ceramic overvoltage protection device with dual function low capacitance and improved durability of claim 72, said capacitive coupler has a capacitance of at least 1000 pF to no more than 23,000 pF. According to claim 52, the leakage current of the ceramic overvoltage protection device having dual functions, low capacitance and improved durability is not greater than 5000 nA. According to claim 74, the ceramic overvoltage protection device with dual function, low capacitance and improved durability has a leakage current of less than 1000 nA. According to claim 75, the leakage current of the ceramic overvoltage protection device with dual function, low capacitance and improved durability is not more than 50 nA. According to claim 76, the ceramic overvoltage protection device with dual function, low capacitance and improved durability has a leakage current not greater than 5nA. According to claim 77, the leakage current of the ceramic overvoltage protection device with dual function, low capacitance and improved durability is not more than 1 nA. A ceramic overvoltage protection device having dual function low capacitance and improved durability according to claim 52, wherein said first insulator is thinner than a minimum separation distance between internal electrodes of said capacitive coupler.

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