WO2008031189A1

WO2008031189A1 - Failure resistant capacitor structure

Info

Publication number: WO2008031189A1
Application number: PCT/CA2007/001460
Authority: WO
Inventors: David A. Kelly
Original assignee: Kelly David A
Priority date: 2006-09-13
Filing date: 2007-08-21
Publication date: 2008-03-20
Also published as: WO2008031189B1; CA2560027A1

Abstract

A failure resistant capacitor, using ceramic as a part of the dielectric structure. The capacitor is made using at least one failure resistant electrode forming one polarity of electrode in capacitor. The dielectric layers separating the electrodes are composed at least partly of a high K ceramic material. Each layer of the capacitor has an electrode on one side of a dielectric layer, which is then assembled such that there is at least one alternating failure resistant electrode with at least one dielectric layer separating an adjacent opposite polarity electrode. The failure resistant electrode is designed to be capable of disconnecting a defect in the dielectric layer from the rest of the capacitor structure. Alternately, the capacitor may be constructed with an electrode structure that limits the energy discharged through a defect in the dielectric layer to an amount predefined by the electrode construction. The dielectric layer may be composed of fused ceramic dielectric layers or from a ceramic polymer dielectric.

Description

FAILURE RESISTANT CAPACITOR STRUCTURE

FIELD OF THE INVENTION

The field of the invention relates to a capacitor construction where at least part of the dielectric consists of a high K ceramic material, with special electrodes that are resistant to failure and provide isolation, to predetermined amount, of capacitor defects from external circuits. The dielectric layer is often a ceramic polymer mixture or alternately a fused structure principally composed of a high K ceramic. The resistant to failure electrode structure is well suited to capacitors specifically designed for high energy density and energy storage.

BACKGROUND OF THE INVENTION

Traditionally, batteries of many different types and construction has filled the role of electric energy storage devices, but they suffer from a limited life and a slow rate of recharge. The development and demand by the public for pure electric or hybrid cars, electric scooters and renewable energy sources such as solar or wind power has created the need for an inexpensive, long lived, fast to recharge electric storage device. The development of various super capacitor technologies has tried to fill the need for such an electrical device. Each of the various super capacitor technologies developed have specific technical limits to their operation. Lower cost super capacitor designs are constantly being researched with the goal of developing and meeting the public's requirement for such an inexpensive device.

Various industries require the continued development of inexpensive capacitors and electric energy storage devices using high K dielectric materials, where 'K' refers to the dielectric constant. For example research into Relaxor Ferro-Electric ceramics, has lead to the discovery of materials with properties that are well suited for use in a capacitor, with dielectric constants up to 100,000 but, a number of the most promising materials are not compatible with current ceramic capacitor manufacturing technology. Further, problems have been recognized with existing ceramic super capacitor technology such represented by US7,033,406, where a short circuit across a dielectric layer between oppositely charged electrodes results in sudden destruction of the capacitor and at times the destruction of the capacitor assembly being used as an ESU (Energy Storage Unit). Another problem with ceramic capacitors is the development of internal cracks, across the dielectric insulating layers, caused by thermal shock, impurity, voltage surge, mechanical stress from improper handling and the manufacturing process. These cracks and defects represent weak spots within the dielectric insulating layer, often the location where an electrical short circuit develops during normal operation. To reduce the risk of an electrical short circuit manufacturers have to substantially increase the thickness of the dielectric layer making the ceramic capacitor larger and more expensive than a failure resistant capacitor structure would require.

A ceramic super capacitor energy storage device, manufactured using the traditional ceramic capacitor method of construction, often uses hundreds of capacitors connected in a parallel arrangement, with each capacitor having tens to hundreds of insulating dielectric layers. This means that each energy storage device contains tens of thousands of insulating dielectric layers where a short in a single layer would result in the discharge of the whole energy storage device into a single capacitor, often destroying the capacitor. To reduce the threat of destruction of a ceramic super capacitor energy storage device, by such a common failure mode, the addition of external current limiting or fuse element to each capacitor or group of capacitors is required. The purpose of the fuse device is to disconnect the failed capacitor from the energy storage device in such a way that the energy storage device will continue to function, even though one or more elements have failed. The use of thick dielectric layers in a ceramic super capacitor in addition to external fuse devices increase the size and expense of an energy storage device using conventional design practices.

Polymer film capacitors of current manufacture are relatively mature, efficiently utilize available dielectric material, are low cost to manufacture and may be designed to be failure resistant, such that an internal dielectric short circuit clears in such a manner that the capacitor continues to function as intended. The mechanical and electrical performance of polymer film capacitors are ideal in all ways except the dielectric constant of polymer film is only 1/2000 that of a high K ceramic material.

There are many different patents that provide information about current state of the art in capacitor design and manufacture such as US 6,426,861 for polymer, US6,544,651 for ceramic polymer and US 7,027,288 for ceramic. US7,033,406 is an example of an ESU (Electrical Storage Unit) that uses state of the art ceramic capacitor technology in its manufacture. The ceramic capacitor used in the ESU have no mention of fuse elements or other electrode technology to provide a degree of failure resistance. The capacitor design relies on a void free ceramic glass matrix where the structure is about 10% by volume a special glass. The absence of any form of failure resistant or fuse element in the ceramic structure makes the capacitor at risk of melting or become severely damaged, should a dielectric layer fail. The use of ceramic glass composite matrix improves some properties but still leaves the capacitor sensitive to cracking if subjected to mechanical stress. US4, 247,881, 7,027,288 and 7,099,141 demonstrate two different methods of failure resistance, should an insulating dielectric layer fail.

SUMMARY OF THE INVENTION

The present invention provides a new capacitor construction and method of manufacture where the insulating dielectric material is composed principally of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where the ceramic powder comprises as much as 95% by volume, of the resulting electrically insulating dielectric matrix. The polymer compound for example may be based on an epoxy, silicone, polyurethane, polyamide etc. base, using either addition or thermal cure to change from a liquid to solid phase. The polymer compound often uses many types of additives to slow the cure process, solvents to reduce the viscosity of the ceramic polymer mixture, adhesion promoters to improve the bonding strength of the polymer to the ceramic particles and substrate.

Another aspect of the invention where an electrically insulating dielectric layer is composed principally of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where the ceramic powder comprises as much as 95% by volume, is subjected to heat and pressure, perpendicular to the plane of the electrodes during the curing or setting up process of the polymer compound, where after the curing process has completed remaining voids have been removed or contain gas at a high pressure, increasing the remaining void breakdown voltage.

Yet another aspect of the invention where a capacitor electrically insulating dielectric layer is composed principally of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where the polymer compound is a soft elastic compound such as a silicone gel, acrylic or other adhesive that adheres to the ceramic powder after curing.

An aspect of the invention where an electrically insulating dielectric layer is composed principally of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where the polymer compound is diluted with a solvent compatible with both the ceramic powder and polymer compound to make the electrically dielectric insulating material easier to form into layers during manufacture and the solvent is evaporated from the solid matrix during the manufacturing process. An aspect of the invention where an electrically insulating dielectric layer is composed principally of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where: the electrically insulating dielectric material is stacked with alternating electrode layers, where a number if not all the electrodes are connected to one of at least two common electrodes located on different sides of the capacitor, and each common electrode is electrically isolated from each other and comprise one part of the capacitor electrical circuit.

One aspect of the invention that may be applied to the new method of ceramic polymer and conventional ceramic capacitors design where at least one set of electrodes are purposely made to be high resistance, lkilo to lMega ohm per square, to limit the energy applied to a dielectric short circuit. In the circumstance where the short circuit is permanent, the high resistance electrode will limit the power the capacitor draws from the external power source. Another embodiment of the invention that may be applied to the new method of ceramic polymer capacitor construction and conventional ceramic capacitors design is, where at least one set of electrodes are made from a PTC (Positive Temperature Coefficient) high resistance material lkilo to lMega ohm per square, which limits the current applied to a dielectric short circuit. If the short circuit is permanent, the highly resistive PTC electrode will greatly increase in resistance as the electrode increases in temperature, as power is dissipated in the short circuit, limiting the power dissipated by the shorted capacitor to a safe or predetermined value.

5 In an embodiment of the invention the high resistive PTC electrodes in a ceramic polymer capacitor are made from a very small amount of polymer combined with a fine electrically conductive PTC high resistance ceramic.

Yet another embodiment of the invention uses a floating electrode made of high resistance PTC material lkilo to lMega ohm per square, divided into two parts connected

) together by a very thin section where the thin section is convoluted to simulate a long section. The long thin interconnection section increases the resistance and voltage blocking capability during a fault condition.

Yet another embodiment of the invention uses a floating electrode made of high resistance material lkilo to lMega ohm per square, divided into two parts connected together by

> a very thin section that is capable of acting like a fuse, where the thin section is convoluted to simulate a long section. The long thin interconnection section increases the resistance and facilitates the fusing action providing a higher voltage blocking capability during a fault condition.

Another embodiment of the invention uses an output electrode made of high resistance

⁾ PTC material lkilo to lMega ohm per square, divided into two parts where the outer end that provides an external electrical connection is separated from the rest of the electrode by a thin convoluted section that adds additional resistance between the outside connection and the inner part of the electrode. The long thin interconnection section increases the resistance and voltage blocking capability during a fault condition. Another embodiment of the invention uses an output electrode divided into two parts where the outer end that provides an external electrical connection is separated from the rest of the electrode by a thin convoluted section, often made from a material that is capable of acting like a fuse, that adds additional resistance between the outside connection and the inner part of the electrode. The long thin interconnection section increases the voltage blocking capability of the fusible section during a fault condition.

In specific embodiments of the invention, applied to the new method of ceramic capacitor construction and conventional ceramic polymer capacitor design, the electrically insulating dielectric layer between opposite polarity electrode layers, is broken into at least two intermediate insulating layers, where each intermediate insulating layer has an isolated floating electrode made of high resistance material lkilo to lMega ohm per square often with PTC properties, such that a short or failure of one intermediate insulating layer doesn't create a short circuit through the whole insulating dielectric structure. The breaking up of a single electrically insulating layer into multiple intermediate layers provides a form of failure resistance for the capacitor so long as the remaining electrically insulating dielectric layer(s) is capable of carrying the full voltage applied across it. The advantage of this specific embodiment is applicable to capacitors operating at high voltages and will allow the thickness of the dielectric layers to decrease, reducing size, manufacturing cost and improve the reliability of the capacitor. In another specific embodiments of the invention, applied to the new method of capacitor construction and conventional ceramic capacitors design, where the electrode is purposely made of suitable high resistance material often lkilo to lMega ohm per square and comprised of a material that will fuse or change into an electrically insulating material if high temperatures are applied to it, such as experienced during a dielectric short circuit, acting like a fuse isolating the area of electrically shorted dielectric area from the rest of the capacitor. The purpose of this construction is to provide a failure resistance capability to the capacitor, improving reliability and allowing the use of thinner dielectric material that will reduce the cost of manufacture. Further, in other specific embodiments of the invention, applied to the new method of capacitor construction where an electrically insulating dielectric layer is composed of up to 95% of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where the electrically insulating dielectric material is first formed into tapes with an electrode structure formed on one side by suitable means, then the tapes are stacked, where a number, if not all the electrodes, are connected to one of at least two common electrodes located on different sides of the capacitor, where each common electrode is electrically isolated from each other and comprise one part of the capacitor electrical circuit.

In other specific embodiments of the invention, applied to the new method of capacitor construction, where an electrically insulating dielectric layer is composed of up to 95% of a ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound, where the electrically insulating dielectric material is directly deposited by a method that produces an insulating layer with the required mechanical and electrical properties on top of a proceeding layer followed with an electrode structure directly deposited by a method that produces a conductive layer with the required mechanical and electrical properties. The process is repeated forming a layered structure comprising of alternating electrically insulating dielectric layers followed by an electrode layer where a number if not all the electrodes are connected to one of at least two common electrodes located on different sides of the capacitor, where each common electrode is electrically isolated from each other and comprise one part of the capacitor electrical circuit.

Other specific embodiments of the invention, applied to the new method of capacitor construction, where an electrically insulating dielectric layer is composed of any amount of ceramic dielectric powder, typically smaller than 1 micron in size, bound together into a void free solid matrix with a polymer compound using special electrode construction as required to meet the requirements of the intended application.

In all specific embodiments of the invention high resistance conductive electrodes may be made greater than 1 Mega ohm per square.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a number of different capacitor electrode structures;

FIG. 2 represents commonly used alternating arrangement of dielectric and electrode layers in a capacitor;

5 FIG. 3 represents a failure resistant alternating arrangement of dielectric and electrode layers in a capacitor;

FIG. 4 represents another failure resistant alternating arrangement of dielectric and electrode layers in a capacitor;

)

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment, not shown in any figure, in accordance with the present invention is the fabrication of a capacitor dielectric layer, using a mixture consisting of a high K ceramic powder typically 1 micron in diameter or less, polymer compound with curing agent, compatible solvent and other additives to modify the viscosity to the desired value and improve adhesion of the polymer to the ceramic powder and substrate. Typically but not limited to, the dielectric has up to 95% high K ceramic material by volume. The polymer agent fills any voids that may be present and acts like an adhesive to bind the ceramic material together and to neighbouring layers with it often having elastic properties throughout the life of the capacitor. During capacitor manufacture solvent is removed from the dielectric layer(s) as well as trapped gas. Appropriate pressure, process temperature are applied after the capacitor is assembled and during the curing process.

The polymer compound for example may be based on an epoxy, silicone, polyester, polyurethane, polyamide etc. base, using either an addition or thermal cure to change it from a liquid to solid phase. The polymer compound often uses additives to slow the cure process, solvents to reduce the viscosity of the ceramic polymer mixture, adhesion promoters to improve the bonding strength of the polymer to the ceramic particles and substrate. Compounds or additives that disperse the ceramic particles evenly throughout the polymer are desirable in the preferred embodiment.

The dielectric made in this preferred embodiment has polymer content often more than 5% by volume, bonds to the ceramic particles with an electrical breakdown no less than the ceramic powder and has high corona resistance. If a dielectric failure should occur the polymer compound in conjunction with the ceramic powered do not evolve high volumes of free gas but chemically react forming an electrically insulating, inert solid with a similar volume to the original ceramic polymer mixture.

The side views in all FIGURES are greatly exaggerated for clarity where dielectrics are 1 to 10' s of microns thick, the thicker layers used for higher working voltages and the electrode is typically 0.01 to 1 micron thick.

The embodiment in FIG. 1 in accordance with the present invention provides representative details about the various electrode structures that are used in combination each other to form various types of capacitor structures, some of which offer a degree of failure resistance. In FIG. 1 numbers 100, 103, 107, 110, 115, 120, 130 and 140 represent different layers that maybe used in a ceramic polymer and conventional ceramic capacitor construction. Layer 100 is shown with both a top and a side view of the structure, where 101 represents a dielectric material of ceramic or ceramic polymer construction with electrode 102 formed on the dielectric with no outside electrical connection. Layer 103 is shown in both a top and side view of the structure, where 105 represents a dielectric material of ceramic or ceramic polymer construction with two isolated electrodes 104,106 shown exaggerated in thickness. The electrodes are often formed by screen-printing, spraying or any other suitable method of deposition directly on the dielectric with both electrodes having separate outside electrical connections. Layer 107 is shown in both a top view and side view of the structure, where 109 represent a dielectric material of ceramic or ceramic polymer construction with an isolated electrode 108 formed as before, on the dielectric with an outside electrical connection. Layer 115 is shown in both a top view and side view of the structure, where 117 represents a dielectric material of ceramic or ceramic polymer construction with an electrode 116 formed, as described before, on the dielectric with an outside electrical connection. Substrate 110 is shown in both a top view and side view of the structure, where 112 represents a substrate of material which a capacitor stack may be formed on top of, where the substrate is typically a ceramic or ceramic polymer construction with electrically isolated electrodes 111 and 113 formed on top and around the substrate ends. Electrodes 111, 113 provide an electrical connection to the capacitor electrodes, in the above electrode layers and with an external electrical circuit.

Another preferred embodiment, typically but limited to conventional ceramic capacitors, that uses structures similar to FIG. 1, has the conductive electrodes made from a highly resistive material lkilo to lMega ohm per square, preferably with a highly PTC (Positive Temperature Coefficient) property. Such a ceramic capacitor would be fabricated using conventional manufacturing methods except the electrode structures are preferably made from a high resistive PTC semi-conductor ceramic rather than a metal alloy. The purpose of the highly resistive electrode is to limit the dielectric short circuit power dissipation to a level that the capacitor structure can tolerate. Alternately, one or all of the electrodes may be formed from an electrically conductive high resistance material that turns into an inert insulating solid after being subjected to high temperatures for prolonged periods of time. The purpose of the fusible electrode is that the heating of the dielectric due to the short circuit will convert the normally conductive electrode material into an electrically insulating material disconnecting the short area from the rest of the capacitor.

For example, a capacitor with a PTC high resistance, lkilo to lMega ohm per square electrode structure, a capacitance value of 0.001 Farad, made up of 100 layers has a capacitance of 10 microfarad per layer. The capacitor is used for bulk energy storage where it is subjected to the charging and discharging in intervals of greater than 10 seconds. The use of highly resistive electrodes giving a combined R x C (resistance times capacitance) time constant of 1 second would add much less than 0.1% of additional charging time. The allowed electrode resistance can be calculated as follows

R x C = Time in this case = 1 second; where C = 10 microfarad. (1)

Solving for R we get R= 100,000 ohms

Preferably the capacitor electrodes are made from a material such as doped BaTiO₃ a commonly used ceramic PTC material, with a resistance of 100,000 ohm at 100 Celsius increasing quickly by 10,000 times at 150 Celsius. Such a material property is discussed in a paper by Duk-Hee Kim, Woo-Sik Um and Ho-Gi Kim titled 'Electrical breakdown of the positive temperature coefficient of resistively barium titanate ceramics' the Journal of Materials Research, Vol. 11, No. 8 Aug 1996. An example of the manufacture of a suitable ceramic PTC semiconductor material is described in detail in patent US 4,222,783. The capacitor electrode structure is often screen printed using a mixture containing a fine powder of PTC semiconductor ceramic, typically 1 micron particle size or less in combination with a suitable solvent with additives in a similar manner as a metal electrode would have been constructed. The temperature at which the PTC rapidly changes its resistance can be changed to much lower temperatures for example 100 Celsius.

Example 1: Working voltage of the capacitor is 3,500 volts, an electrode resistance of 100 kilo-ohm would limit the fault current to

I = V/R where V= 3500 volt, R = 100,000 ohm (2)

I = 0.035 ampere

Power Dissipation

Power = V x V / R for the above values (3)

Power = 120 Watt (4)

At 150 Celsius, the resistance increases to R = 1,000,000,000

I = 0.0000035 ampere and

Power = 0.012W significantly lower (5)

If the charge and discharge time of the Capacitor was greater than 60 seconds then an initial electrode resistance value 6 times larger could be used. In practice electrode resistance values of 1,000,000,000 at 150 Celsius are not likely to be achieved due to secondary leakage currents between the thin dielectric layers, often used in ceramic capacitors.

Stress on the ceramic polymer or ceramic capacitor during failure of a dielectric layer is proportional to the power applied to the small area of damage. In most ceramic capacitors the peak temperature across the damaged dielectric layer exceeds 1500 Celsius, often sufficient in magnitude to melt the ceramic with the localized sudden temperature causing the ceramic to explosively expand, cracking neighbouring layers propagating the short circuit even further. Usually capacitors have individual electrode impedance of only 1 to 1000 ohms per square so when the dielectric fails as in the above example, the applied power to a dielectric short is

5 Power = V x V / R where V =3,500, R = 10 from (3) above

Power = 1,225,000 Watts (6)

The weight of the dielectric material in the area of the short is often just a few 10's of micrograms, where the total energy required to melt the dielectric would be about 1.0 Joule. If the applied power is 1,225,000 Watts (6) above, the time required to melt the dielectric material

0 in the area of the short circuit would be less than 1 micro-second, nearly instantaneous not allowing the neighbouring ceramic layers time to conduct the heat away. Using a highly resistive electrode as in the above example, the power initially dissipated in the shorted area would be 120W (4) would take over 8 milli-second to melt the ceramic in this area, providing the neighbouring layers time to conduct a substantial amount of the power away from the fault

.5 further increasing the amount of time to melt the ceramic well beyond 8 milli-second. With the neighbouring layers quickly heated by the short circuit, the temperature of the surrounding electrode made from PTC material will exceed the temperature at which it increases in resistance, eventually dropping the power to 0.012W (5). If during the rapid heating a neighbouring layer is also damaged then the heating causes its electrode to increase in resistance.

10 The result is only one or two damaged layers, with the dissipated power in the area of the short limited to levels that stop propagation of the damage further. Ideally, the PTC material in the area of the shorted dielectric would chemically react with its self or the surrounding dielectric material, turning permanently into an electrical insulator isolating the short circuit from the rest of the capacitor, healing the damaged area. The use of a highly resistive electrode structure such

J5 as provided in the above example increases substantially the amount of time that the electrode would have to chemically react and become an inert material before damage to neighbouring layers could occur. The use of a high resistive electrode material, preferably with PTC properties that is capable of turning into an electrical insulator, when subjected to high fault power would make the all ceramic or ceramic polymer capacitor failure resistant. Such a capability would

50 greatly improve product safety and reduce manufacturing costs through higher yields during the manufacturing process.

The above example shows that the fault power to the defect is limited to a peak of 120W (4) and as the damaged part quickly heats up drops to less than 0.012W (5) at 150 Celsius. If the capacitor in example 1 was part of a 50kW-hour, 31 Farad, 3,500-volt energy storage unit then the failed part would discharge 90 percent of the energy in

Time = R x C where R = 1000 Mega-ohm and C = 31 Farad

Time = 980 years

The discharge of the energy storage unit because of a short circuit in a capacitor layer would be negligible in relation to the rate of self-discharge of an individual capacitor.

FIG. 1 reference 150 shows a greatly exaggerated section of electrode that is used to further increase the resistance of the electrode, made from PTC or other material. The electrode convolutions are often only a few microns in width with the spaces similar in dimension. The thin convoluted sections increase the resistance of the electrode, improve voltage-blocking capability and facilitate fusing of the electrode, if the electrode is made from a fusible material. This example shows 2 convoluted sections in parallel which may in practice be any number from none and up. Reference 120 shows the convoluted section 122 being placed in the middle of a floating electrode, splitting it into two parts 121 and 123. Reference 130 and 140 places the convoluted section 131 and 141 respectively at the electrode end just prior to the part making connection outside of the structure.

FIG. 2 is a typical capacitor construction used for the manufacture of capacitors and is applicable to ceramic polymer capacitors, where 205 are individual conductive surfaces connecting the individual electrodes 203 one side and 202 the opposite polarity electrodes to their respective end electrodes 200 and 204. Where 201 is the dielectric material. This structure is made up using FIG.l layers 107, 115 and 110. In a preferred embodiment at least one electrode is made from a high resistance 1 kilo to 1 Mega ohm per square material often with PTC characteristics using electrode structures such as FIG.l 130 and 140.

FIG. 3 is a type of failure resistant capacitor construction where 306 are individual conductive surfaces, connecting the individual electrodes 303 one side and 302 the opposite polarity electrodes to their respective end electrodes 300 and 305. Where 301 is the dielectric material. At least one floating electrode 304 is placed between every other electrode 302 and 303. The floating electrode divides the dielectric layer into two parts, such that a failure in one part leaves the remaining part to support the voltage between electrodes 302 and 303. Normally electrodes 304 are at half the potential of 302 and 303 but if one of the dielectric layers fails the remaining dielectric layer will support the voltage difference between electrodes 302 and 304. Additional layers of isolated floating electrode 304 may be used to further divide the dielectric structure into smaller sections. This structure is made up using FIG.l layers 100, 107, 115 and 110. In a preferred embodiment at least one electrode is made from a high resistance 1 kilo to 1 Mega ohm per square material often with PTC characteristics using electrode structures such as FIG. 1 120, 130 and 140.

FIG. 4 is a failure resistant capacitor construction where 406 are individual conductive surfaces connecting the individual electrodes 401 one side and 402 the opposite polarity electrodes to their respective end electrodes 400 and 405. Where 403 is the dielectric material. One electrode 404 is placed between every other electrode 401 and 402 and prevents a hard short circuit in the event of a dielectric layer failure, so that normally, the electrodes 404 are at half the potential of 401 and 402 but if one dielectric layer shorts the remaining dielectric layer will hold off the potential difference between electrodes 401 and 402. This structure is made up using FIG.l layer 100, 103 and 110. In a preferred embodiment at least one electrode is made from a high resistance 1 kilo to 1 Mega ohm per square material often with PTC characteristics using electrode structures such as FIG. 1 120, 130 and 140.

Although the invention has been described in connection with a preferred embodiment, it should be understood that various modifications, additions and alterations may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A multi-layer ceramic capacitor comprising; and a) ceramic deposited in layers to form dielectric volumes and dielectric surfaces; and b) a first set of high resistance electrically conductive electrodes deposited on every second dielectric layer; and c) a second set of electrically conductive electrodes offset from the first, deposited on the dielectric layers that are without the first electrodes; and d) forming an alternating structure of first dielectric layer followed by a first electrode, then another dielectric layer followed by a second electrode; and e) the structure is repeated in said sequence until the desired number of layers have been formed; and f) where the first electrodes are electrically connected together to form one polarity of a capacitor; and g) the second electrodes are electrically connected together to form a second polarity of a capacitor and are electrically isolated from the first electrodes.

2. As in claim 1 but the second electrodes are made from a high resistance electrically conductive material same as the first electrodes.

3. As in claim 1 but the first set of electrodes are made using a high resistance PTC electrically conductive material.

4. As in claim 1 but all electrodes are made using a high resistance PTC electrically conductive material.

5. As in claim 1 but the first electrode is made from a fusible high resistance conductive material that when subjected to the high temperatures of a short circuit, converts in the area of the fault to a much higher resistive electrically conductive material, reducing the electrical energy conducted in to the area of the short circuit.

6. As in claim 1 except the first electrode is made from a fusible high resistance conductive material that converts into an electrical insulating material and no longer conducts electrical energy from the capacitor into the area of the short circuit.

7. As in claim 1 but the first high resistance electrode is split into an outer electrode providing an external electrical connection separated by a thin convoluted section to an inner electrode, where the purpose of thin convoluted section is increase further the resistance of the inner electrode portion from the external electrical connection.

8. As in claim 1 but the first electrode is made from a high resistance fusible electrically conductive material and is solit into an outer electrode orovidinε an external electrical connection separated by a thin convoluted section to an inner electrode, where the purpose of thin convoluted section is to increase further the resistance of the inner electrode portion from the external electrical connection and to convert permanently to a much higher resistive material when conducting the energy of a short circuit to the inner portion of the electrode through it from outer portion of the electrode.

9. As in claim 1 but the first electrode is made from high resistance PTC electrically material and is split into an outer electrode providing an external electrical connection separated by a thin conductive convoluted section to an inner electrode, where the purpose of thin convoluted section is to increase further the resistance of the inner electrode portion from the external electrical connection and to convert to even a higher resistance material when conducting the energy of a short circuit to the inner portion of the electrode through it from outer portion of the electrode.

10. A multi-layer ceramic capacitor comprising; and a) ceramic deposited in layers to form dielectric volumes and dielectric surfaces; and b) a first set of high resistance electrically conductive electrodes deposited on every third dielectric layer; and c) a second set of electrically conductive floating electrodes, that have no electrical connection outside the capacitor structure and have no electrical connection to any other electrically conductive layer, deposited on every third dielectric layer following the first electrodes; and d) a third set of electrically conductive electrodes offset from the first, deposited on the remaining dielectric layers that are without the first or second electrodes; and e) forming an alternating structure of first dielectric layer followed by a first electrode, then another dielectric layer followed by a second floating electrode, another dielectric layer followed by a third electrode offset from the first electrode; and f) the structure is repeated in said sequence until the desired number of layers have been formed; and g) where the first electrodes are electrically connected together to form one polarity of a capacitor; and h) the third electrodes are electrically connected together to form a second polarity of a capacitor and are electrically isolated from the first and second electrodes.

11. As in claim 10 but only the electrically isolated floating second electrodes are made from a high resistance electrically conductive material.

12. As in claim 10 but all electrodes are made from the same material as the first electrode.

13. As in claim 10 but at least one set of electrode are made using a high resistance PTC electrically conductive material.

14. As in claim 10 but all electrodes are made using a high resistance PTC electrically conductive material.

15. As in claim 10 but the at least one set of electrodes are made from a fusible high resistance conductive material that when subjected to the high temperatures of a short circuit, converts in the area of the fault to a much higher resistive electrically conductive material, reducing the electrical energy conducted in to the area of the short circuit.

16. As in claim 10 except at least one set of electrodes is made from a fusible high resistance conductive material that converts into an electrical insulating material and no longer conducts electrical energy from the capacitor into the area of the short circuit.

17. As in claim 10 but the first electrode is made from electrically conductive high resistance material and is split into an outer electrode providing an external electrical connection separated by a thin convoluted section to an inner electrode, where the purpose of thin convoluted section is increase further the resistance of the inner electrode portion from the external electrical connection.

18. As in claim 10 but the first electrode is made from a high resistance fusible electrically conductive material and is split into an outer electrode providing an external electrical connection separated by a thin convoluted section to an inner electrode, where the purpose of thin convoluted section is to increase further the resistance of the inner electrode portion from the external electrical connection and to convert permanently to a much higher resistive material when conducting the energy of a short circuit to the inner portion of the electrode through it from outer portion of the electrode.

19. As in claim 10 but the first electrode is made from a high resistance PTC electrically conductive material and is split into an outer electrode providing an external electrical connection separated by a thin convoluted section to an inner electrode, where the purpose of the thin convoluted section is to increase further the resistance of the inner electrode portion from the external electrical connection and converts to a higher resistance material when conducting the energy of a short circuit to the inner portion of the electrode through it from outer portion of the electrode.

20. As in claim 10 but the first electrode is a low resistance conductive material with the inner floating electrode made from a high resistance electrically conductive material and it is split into two equal areas separated by a thin convoluted section, where the purpose of the thin convoluted section is to increase further the resistance between the two half floating electrode and converts to a higher resistance material when conducting the energy of a short circuit between one half of the floating electrode through it to the other half of the floating electrode.

21. As in claim 10 but more than one electrically isolated floating electrodes are placed between the electrodes with external electrical connections.

22. As in claim 1 except a ceramic polymer material is used instead of ceramic for the dielectric layers.

23. As in claim 1 except a ceramic polymer material is used instead of ceramic for the dielectric layers and a polymer based PTC material is used for the electrodes.

24. As in claim 10 except a ceramic polymer material is used instead of ceramic for the dielectric layers.

25. As in claim 1 except a ceramic polymer material is used instead of ceramic for the dielectric layers and a polymer based PTC material is used for the electrodes.

26. As in claim 1 except the high resistance conductive electrodes are greater than 1 Mega ohm per square.

27. As in claim 10 except the high resistance conductive electrodes are greater than 1 Mega ohm per square.