CN1030842A - Electrical overstress protection material and technology - Google Patents
Electrical overstress protection material and technology Download PDFInfo
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- CN1030842A CN1030842A CN87105596A CN87105596A CN1030842A CN 1030842 A CN1030842 A CN 1030842A CN 87105596 A CN87105596 A CN 87105596A CN 87105596 A CN87105596 A CN 87105596A CN 1030842 A CN1030842 A CN 1030842A
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Abstract
A kind of in order to prevent that the rise time is shorter than the material of several nanoseconds or the transition of shorter electricity overload.This material by the coating that separates the conductor material particulate of insulating material and the matrix that the semi-conducting material particle mixture forms constitute; form particle chains in the substrate; along the separating distance between the particulate of chain less than the hundreds of dust; thereby allow that electric word is with the transition of high energy electricity, the particulate intercropping quantum tunneling that is separating.
Description
The present invention relates to generally prevent the electricity overload of electronic device, particularly the protection electronic device exempts from the transition overload that the rise time is extremely short and peak power is very high.
As everyone knows, must prevent that circuit from surpassing the transient voltage and the power supply appearance of its capacity permission.This electric transition may damage circuit, also can cause the misoperation of circuit.Particularly, prevent the interference of electricity overload to hyundai electronics communication and control system.Because of the solid microelectronic element of these systems, be extremely responsive to super-high-current and too high voltages.
Having known has various Apparatus and method fors that the limited protection that electricity is transshipped can be provided.Fundamental method normally adopts the method shielding of chassics earth line, makes electronic device not be subjected to the influence of electromagnetism transition.But this shielding measure can not make electronic device exempt from via connecting the transition interference that lead penetrates the circuit of conductively-closed.Disturb in order to make circuit exempt from this transition overload, normally use separately or combine and use various protection devices.These devices comprise: fusible link, discharger, rheostat, Zener diode, Transzorbs, thin-film device, shunt capacitance, inductor and filter.These elements voltage of doing commonly used suppresses or voltage limitator, still, and so-called electricity overload (EOS) protection device.In use, the EOS protection device is connected between the circuit and ground to be protected, or be connected and lead and ground that circuit to be protected links between.Its purpose is, before the circuit of the energy possibility injury protection that transition produces, the EOS transition is switched to ground.
For this purpose, the EOS transition is defined as: can damage or the transient voltage or the electric current of interfered circuit operate as normal.The transition of actual electricity deeply concerned overload may be from electromagnetic pulse (EMP), lightning or Electrostatic Discharge.These transitions can rise to maximum amplitude to a few microsecond in the time at several nanoseconds, and may occur repeatedly.Hereinafter, these EOS transitions also are known as pulse or surge sometimes.
The common example of ESD overload transition is in the office of having spread carpet, and the personnel of dress insulation clothes occur when having accumulated static on one's body.This ESD transition, voltage can surpass 20,000 volts when discharge, and electric current can surpass 40 peaces.The element of computer and other electronic equipments can be disturbed or damage to this transition.The ESD transition can reach crest discharge voltage immediately in several nanoseconds, and also faster than the action of common protection from transients device.
Lightning is the another example that can play the EOS transition of illeffects to electronic circuit.Nearly lightning thunderbolt to several miles is radiation-curable to go out considerable electromagnetic energy, produces the pulse amplitude of thousands of volts on power transmission line.Representationally be, the time that the lightning transition reaches peak value is several microseconds, and even so, this transition is also than slow thousands of times of ESD transition.
The EMP transition is produced by nuclear weapon or other directed high-energy rigs.For example, a nuclear explosion can produce the electric field that surpasses 50,000 volts/rice in radius surpasses 600 miles circumference.This kind electric field can reach peak amplitude in several nanoseconds.The EOS transition that is produced can make communications service and other electronic equipment not work.
The EMP that produces is threatening microelectronic element, particularly junction field effect transistor and microwave diode.H.R.philipp and L.M.Levinson are being stated from J.App.Phys.50(7) (July 1979), be entitled as existing argumentation the in one piece of article of " Nbo Devices for Subnanosecond Transient Protection ".The author points out emphatically: common device is to be used for protecting power supply or low-frequency channel to exempt from lightning or switching surge, and fails to provide sufficient protection to very short EMP transition of rise time.(" rise time " speech refers to transition and reaches the required time of maximum amplitude).
The example of a kind of simple Devices of protection electrical interference is a fusible link commonly used, and it is responsive to the electric current that flows through on the power transmission line.Under big current conditions, heating reaches striking point, and after the disconnection, fusible link causes open circuit.Because heating needs time enough, so fusible link is unsuitable for the situation that need respond extremely rapidly, for example, it is that several nanoseconds EOS transition is reacted that fusible link was not enough to the rise time.In addition, fusible link can not be used for repeatedly the occasion of electrical overstress protection, because after EOS is reacted, fusible link is irreversibly to damage fusing, so the fusible link that must more renew.Wish that fusible link to after EOS protection from transients, can have this better performance of recovering its protective capability automatically.
In fact, this ability that automatically restores to defencive function is in many overload protection devices commonly used, and particularly rheostat possesses this ability to a certain extent.Rheostat generally has the characteristic that is called as " clamper " voltage.When applied voltage was lower than the clamper value, rheostat had high resistance, so play a kind of open circuit effect in fact.On the contrary, for the applied voltage that surpasses the clamper value substantially, rheostat has resistance haply and is reduced to the low resistance that the electric transition of high amplitude is switched to ground.Thereby when a rheostat was connected on the line that is loaded with signal, rheostat can not influence the original voltage on the holding wire.But can disturb the EOS of high amplitude, quite long EOS of some rise time be disturbed bypass to I haven't seen you for ages.
Here, presenting high resistance being lower than clamping level voltage, and present low-resistance characteristic being higher than clamping level voltage, be called nonlinear resistance (NLR).Known many materials have the NLR characteristic.Common example is a zinc oxide.This material is used to for example, usually make rheostat with zinc oxide fine particles in the multiple overload protective device.When this material presents high-impedance state, claim this material to be in " OFF state "; When this material presents low resistive state, claim this material to be in " ON state ".
Rheostat available on the market has enough abilities can satisfy the overload protection of sizable transient energy (as the impact of lightning, surge).But this rheostat has individual shortcoming, is exactly that electric capacity is bigger, has postponed the response time.At " The Transient Voltage Suppressions Manual " (fourth edition, published in 1983 by General Electric Company have introduced this rheostatic structure and operation principle in U.S.A).According to above-mentioned handbook, rheostat is dealt with and is flow through electric current up to 6,000 peaces, the ability of energy up to 200 joules.The fine structure of rheostat material by sintering oxide powder crystal grain form, its voltage drop on grain boundary has the characteristics of approximate constant, generally each grain boundary knot is not about 2～3 volts, and has nothing to do with grain size.
British patent NO 4,103, and 274 have proposed a kind of rheostat material of special use.By this patent, use the polycrystalline metal oxide, particularly the mixed-metal oxides ceramic particle is made rheostat in plastic resin matrix.
Many other devices that are usually used in circuit all have the NLR effect, and have been used for electrical overstress protection.The representative instance of these devices is semiconductor diodes, transistor and Zener diode.Particularly Zener diode had before applied voltage reaches threshold value, and resistance is near infinitely great; After reaching threshold value, the character that its resistance reduces rapidly.Though the response time of Zener diode is faster than other overload protection devices, it still presents some electric capacity, thereby when running into the EOS transition of nanosecond or shorter rise time, it still has significant time delay.And actual Zener diode working range is quite limited, does not also possess the ability of the macro-energy of bearing.
Zener diode and other are usually used in the device of EOS protection, when running into such as the fast transient that caused by EMP, also often present significant " overshoot "." overshoot " speech was meant that before device changes conducting into transient voltage surpasses the numerical value of overload protection device clamp voltage.For example in diode, " overshoot " needed time of can being discharged by the P-n knot diffusion layer of the inductance of lead and diode causes.Because the circuit that links to each other with an overload protection device may be between overshoot period damaged, should reduce the amplitude and the time that continues of overshoot usually as far as possible.
Discharge device also has sizable energy ability to bear to be used for the EOS protection.In the course of the work, the sparkover conduction, owing to form strong ionization conductive channel, its resistance almost can be ignored.Because discharger is for absorbing enough energy to produce this kind passage, the required time can be up to several nanoseconds, so discharger also presented significant overshoot phenomenon before changing strong conduction into.And after discharge device changed low-resistance into, it can make the protective circuit short circuit.
Can comprise multiple loose solid material for the thin-film device of EOS protection, circulation in the electric current very narrow passage within it.Typical channel sized has only sub-micron to arrive micron, so before corresponding thermal limit, can only absorb very a spot of energy.In fact, thin-film device also presents significant overshoot, after few several times reaction is made in transition to this kind, may lose its recovery performance.
Filter is usually by resistor, capacitor, inductor and constitute such as class solid-state components such as diode, transistor and operational amplifiers.Filter has limited to the application in the rapid EOS protection from transients, because by definition, filter only allows some frequency to pass through, and blocks other frequency.For example, electric capacity allows high-frequency signal to pass through, and stops low frequency signal.Because the transition of many fast rise times contains the frequency band of broad, comprise very high or very low frequency component, common filter is unsuitable for doing the EOS protection.
From the above mentioned, can understand that common device and material are not suitable for the rise time and are shorter than several nanoseconds, the protection that the electric transition of wide spectrum is disturbed.In addition, the overload protection device of discrete type respectively has self shortcoming, particularly runs into after the EOS transition of recurrent high energy fast rise time, can't the recovery and protection function.
Primary and foremost purpose of the present invention and advantage provide a kind of improved nonlinear resistance material, and it is several nanoseconds the weak point or the infringement of shorter recurrent transition that protective circuit exempts from the rise time.
Particularly, objects and advantages of the present invention provide and have the nonlinear resistance performance to the ability that the transition of nanosecond fast rise time responds repeatedly, have minimum and controlled overshoot, and bear the electrical overstress protection material than the macro-energy ability.
Especially, objects and advantages of the present invention are to provide a kind of nonlinear resistance material of above-mentioned characteristic, can select different component or geometry, 5～10, in 000 volt the clamp voltage scope, are selected preparation.
In a word; the invention provides a kind of nonlinear resistance material with electrical overstress protection; by size approximately less than the loose particles of the electric conducting material of hundreds of micron; size is approximately less than the loose particles of the semi-conducting material of hundreds of micron and be coated in the material that the insulating material on these particulates that separate is formed, normally mixture uniformly.These particulates mix with matrix equably, and so that unnumbered particle chains to be provided, and the distance between particulate is sufficiently little, so that the electronics between particulate is realized significant electron conduction by means of quantum tunneling.In a preferred embodiment, material of the present invention further comprises a kind of adhesive or packing material, and conductor material and semi-conducting material are mixed fully equably therein.
Also have, the present invention also provides a kind of manufacture method that the rise time is the nonlinear resistance material of several nanoseconds weak point or shorter electric transition of protecting.Comprise that the preparation particle size is approximately less than the step of the conductor material and the semi-conducting material particulate of hundreds of micron; Apply the step of each particulate respectively with insulating material, the thickness of insulation coating is no more than the hundreds of dust; The conductor material particulate that applied is mixed mutually with the semi-conducting material particulate that applied, closely adjacent to form particulate, the matrix step of uniform unnumbered particle chains is convenient to a large amount of electronics with powering up transition outward substantially, moves at adjacent microparticles intercropping quantum tunneling.
The advantage of a uniqueness of overstress protection material of the present invention is; for with various Electrical and Electronic devices; comprise being connected of antenna, Electrical and Electronic circuit, interconnecting lead, printed circuit board (PCB) and integrated circuit component,, all can make easily though shape is ever-changing.
For those of ordinary skill in the art, from following description and accompanying drawing, pass through the preferred embodiment of the invention that provided, can understand fully further purpose of the present invention and advantage.
Fig. 1 is the schematic cross-section that material of the present invention has amplified.
Fig. 2 is the view that the fragment of material shown in Figure 1 further amplifies.
Fig. 3 is to the conductor material weight ratio of the specific components of material shown in Figure 1 and the graph of relation of clamp voltage.
Fig. 4 is another specific components to material shown in Figure 1, the curve chart of OFF resistance and polymer content (weight).
Fig. 5 is applied to various overload protection devices and material, comprises the voltage and the time relation curve of material of the present invention.
Fig. 6 is the overload protection device schematic diagram with material shown in Figure 1.
Fig. 7 is a schematic diagram of explaining the voltage drop at particles of material shown in Figure 1 two ends.
As shown in Figure 1; according to electrical overstress protection material of the present invention; comprise the host material that a conductor particulate 11 and a semiconductive particles 13 by mutual isolation adjacent one another are of representing with label 9 mixes arbitrarily, but structurally separate by insulating material 15.Insulating material 15 extremely thin can permissions between particulate 11 and 13 have the quantum mechanical tunnel of electronics to exist.In the gap between conductor particulate 11 and semiconductive particles 13, fill with jointing material 19.The cross section of composite material 9 as shown in Figure 1 is contained in up and down between the flat metal electrode 21 and 23.Size that it should be noted that the host material between separated two electrodes 21 and 23 only surpasses particulate 11 and 13 sizes several times.And the shape of electrode 21 and 23 is a theme of design alternative.
In order usually to understand the function of host material 9, suppose that electrode 21 is connected on the circuit of EOS transition to be protected, and electrode 23 is connected to the ground of system.So host material 9 becomes the mediator of electrode 21 and 23.
The characteristic of host material 9, the high resistant when being included in OFF state is (usually greater than 10
9Ohm/cm) and the low-resistance during ON state (about 1 to 1000 ohm/cm usually).And host material 9 is to respond the EOS transition with subnanosecond rise time in less than 1 nanosecond cycle, and from the OFF state to the ON state.This host material tangible overshoot can not occur.In addition, host material 9 has surprising ability, after the high energy transition up to 50,000 volts of voltages that stands repeatedly, still can keep its switching capability.
In host material 9, the size of conductor particulate 11 is used under the situation of carbon black powders approximately less than 100 microns, can be little of 100 dusts.As the preferred particle size scope of semiconductive particles 13, be about 0.1 micron to 100 microns usually, and particle size quite few outside this scope.In fact, granule amount above this range limit is minimized, because bulky grain tends to form independent conductive path, this path influences the characteristic of host material conversely, particularly lasting transition repeatedly also may cause catastrophic dielectric breakdown.
Best structure as shown in Figure 2, electrically conductive particles 11 and semiconductive particles 13 are coated with insulating material 15 respectively and apply.In fact insulating material 15 may be made up of to the particulate of 300 dusts 70 dusts itself.Therefore, the insulation particulate approximately be coated conductor particulate and semiconductive particles 13 sizes 1/10th to one thousandth.
In fact, conductor particulate 11 is preferentially formed by carbonyl nickel, is formed by INCO type 255 carbonyl nickel powders specifically.Yet the electrically conductive particles 11 that in host material 9, uses, may be by as directed ramet, titanium carbide, nickel, also have carbonyl nickel, tungsten carbide, boron carbide, zirconium carbide, carbon black, graphite, red copper, aluminium, molybdenum, silver, gold, zinc, brass, cadmium, bronze, iron, tin, beryllium, lead in addition, the material of practical conduction such as boride and mu-metal (Mu-metal) is formed.
The conductor material that constitutes conductor particulate 11 should have about 10
-1Ohm/cm to 10
-6The resistivity of ohm/cm, some suitable resistivity of material are as follows:
1 * 10
-4The ohm/cm titanium carbide
7 * 10
-5The ohm/cm niobium carbide
2 * 10
-5The ohm/cm ramet
1 * 10
-5The ohm/cm tungsten carbide
6 * 10
-5The ohm/cm zirconium carbide
In some application facet, it is favourable forming conductor particulate 11 by metal silicide, because these materials have the resistivity and the high-temperature stability of metalloid.Many metal silicides that are fit to do conductor particulate 11 are set out in " Silicides for VLST Applications " (S.P Murarka(Academic Press, 1983), PP.30～31) in.
Fig. 1 and Fig. 2 have expressed the irregular structure that conductor particulate 11 and semiconductive particles 13 have many cusps and spicule usually.In fact, these shapes have some advantage.The material that spicule is arranged, for example carbonyl nickel strengthens the electric field between particulate, increases the conductivity of host material 9.Strengthening the particular advantage of electric field, is when response has the EOS transition of fast rise time, increases the conversion speed of host material 9 between ON state and OFF state.
Semiconductive particles 13 can be made of any common semi-conducting material.In these preferable material, comprise the based semiconductor of carborundum, beryllium carbide, calcium oxide, chalcogenide, doped silicon, niobium oxide, vanadium oxide, indium antimonide, iron oxide, boron carbide, selenium, vulcanized lead, cadmium sulfide, zinc sulphide, silver sulfide, titanium dioxide boron, selenium, tellurium, germanium and vanadium carbide and also can use by the organic semiconductor of liquid gel technology manufacturing.
Among Fig. 3, represent of the influence of the different component of host material 9 to clamp voltage by the percentage of conductor material and semi-conducting material.Stand the effect repeatedly that 1000 deep-sited pulses are dashed, measure clamp voltage.Certain material as test is made up of the nickel and the semi-conductive carborundum of conductor.Result of the test shows that before the percentage of conductor material was increased to greater than 10%, clamp voltage was near adding the transition amplitude.If the percentage of conductor material is increased to more than 50%, it is several that then clamp voltage just drops to zero point of applying pulse amplitude.
In general, coated fine particles 11 and 13 insulating material 15 must be made quite thinly, so that between adjacent microparticles, quantum tunneling can be arranged, but calamitous dielectric breakdown (use therein term, the catastrophic dielectric breakdown meaning is meant: form irreversible short circuit by its material 9) can not appear.Can provide appropriate insulation material 15 with fine particles or the form that is similar to film coating.For example, a kind of similar film coating can be provided, by under oxygen atmosphere, reacting with conductor particulate 11, make microparticle surfaces generate metal oxide layer (certainly, such reaction, finish before should in host material 9, mixing conductor particulate 11), and, insulating material 15 also must be a kind of can be in host material 9 not with host material in the material of other material chemically reactive.
In fact, the silicon dioxide that insulating material 15 is a kind of preferred fumings for example can be used Cab-O-Sil board silicon dioxide.Other materials that are fit to comprise kaolin, kaolinite, three aquation aluminium, feldspar, various silicide, bead, calcium carbonate, barium sulfate, calcium sulfate and various oil.
A kind of effect of insulating material 15 is that closely controlled structural isolation is provided between conductor particulate 11 and semiconductive particles 13.For the superperformance of satisfactory realization host material 9, a large amount of conductor particulate 11 and partly lead particulate 13 and should be spaced from each other, the scope of the distance that separates approximately from 50 dusts to the hundreds of dust.Best particulate depends on the element that forms conductor and semiconductive particles at interval, also depends on the electric field that the phase of giving adds.In any case the spacing between most of particulates should be very little, press the mean value of material in the body, allow between adjacent the conductor particulate 11 and semiconductive particles 13, can be by the quantum tunneling conduction of electronics, to respond electric transition.
Under the situation that lacks insulating material 21, host material 9 can not recover high-impedance state, but form a quite lasting bypass of low-resistance over the ground after the high energy overload is disturbed.Host material 9 and high energy transition react, and return to high-impedance state then, can be referred to as " persistence ".Another purpose of insulating material provides the sufficient each other physical isolation of conductor particulate 11, and high OFF resistance is provided.Under the situation that lacks insulating material 15, adjacent conductor particulate 11 may form the conductor chains by host material 9, causes that host material 9 OFF state volume resistances make us and can not reduce with allowing.
The material ranges that jointing material 19 can be used all has up to fluid (gas or liquid) from solid-state material.Under solid-state or semisolid, jointing material 19 is in order to the spacing between the maintenance particulate, and the space between the filling particulate 11 and 13.Though the solid state bonds material can form the combination of machinery between particulate, this effect is not crucial, but is convenient to host material 9 is made into different shape and size, is connected with element required for protection.When between particulate, not having mechanical bond, 9 one kinds of structural container of host material must be arranged.The pattern of container or packing is the theme of a design alternative, also may use always.The packaging material that share comprise pottery, epoxy resin, polyester, paint, oil and metal etc., but be not limited thereto.A kind of container of typicalness, the electrode with appropriate intervals is in order to contact reliably with the host material 9 of packing into.
In general, jointing material is that a kind of resistivity is from 10
12To about 10
15The insulating material of ohm/cm.In fact, jointing material 19 is heat curing copolymer preferably, comprises epoxy resin, thermoplastic rubber or polymer alloy and admixture.Jointing material 19 also can be made up of the electrical insulating material of routine, in the material that is suitable under different situations, includes pottery, oil, fuming silicide, even water, air, vacuum and N
2And SF
6Such gas.
Because jointing material 19 is a kind of electrical insulators, it can influence the clamp voltage of host material 9.For example, by the semiconductive particles 13 of identical weight percentage component and the host material of conductor particulate 11 formations, owing to use different types of jointing material 19 can obtain different clamp voltages.This effect mainly is that the dielectric constant of jointing material 19 works.Therefore, if host material needs the low electric capacity of tool, so, the benefit that forms jointing material 19 by polymer is to reduce the total dielectric constant of host material 9, and the dielectric constant of this material must be little usually.If desired the host material of high capacitance (host material 9 is used for the occasion of circuit element design, for example, strip line, PCB material, cable.Coaxial connector spare or other devices, this transmission line impedance are important places), can increase the dielectric constant of jointing material 19 targetedly, make it to have required condensance.
Jointing material 19 also influences the OFF state impedance of host material 9.So Fig. 4 has expressed the functional relation (longitudinal axis that should be noted that Fig. 4 be logarithmic coordinates) of OFF resistance as the percentage by weight of polymeric material 19.For the OFF resistance that obtains host material 9 significantly changes, the content of jointing material 19, by weight percentage, typical scope is approximately greater than 10% to 35%, is increased to approximately 30% up to jointing material content, and host material 9 still relatively can conduct electricity.
In order further to control OFF state and ON resistance, can be added to plasticizer and coupling agent in the jointing material 19.In fact we find, add 1～5% plasticizer by weight, arrive in the 1000CPS scope 20, cause that the OFF resistance of host material 9 changes up to 6 orders of magnitude.
A special case of host material 9 components by weight, is 2%Cab-O-Sil, 12% carbonyl nickel, 30% epoxy resin and 56% carborundum.Another representative instance of host material 9 components is: 22.5% carbonyl nickel, 43% carborundum, 2.5%Cab-O-Sil and 32% epoxy resin.In these components, conductor particulate 11 is formed by carbonyl nickel, and semiconductive particles 13 is formed by carborundum, and insulating material 15 is formed by Cab-O-SiL, and jointing material is to be formed by epoxy resin.In the typical component, host material 9 generally will contain about 1% to 50% conductor particulate 11.
According to material of the present invention, shown the outstanding effect of response electricity overload transition, the rise time of this transition can be as short as below 0.5 nanosecond.To rise to time to peak longer than 0.3 nanosecond when response, and during than the EOS transition of 1～2 nanosecond of weak point, the host material 9 of different component has all reached does not have tangible overshoot.Fig. 5 represents the typical characteristics of host material 9 when the transition of the about erg-ten energy of response.Situation when Fig. 5 also expresses and is applied to other conventional overload protection devices with identical transient condition.For example, the curve among Fig. 5 " S " expression is added to the voltage pattern at discharge device two ends with identical overload transition.Curve " V " presents a typical rheostat and stands identical transition, the change in voltage situation at two ends.Equally, when curve " E " expression suffers same transition, the voltage at typical Zener diode two ends.In Fig. 5, host material " M " becomes the function that is bordering on constant that equals clamp voltage Vc soon.Should be noted that clamp voltage Vc depends on the component of host material, the characteristic of EOS transition, and the load of being protected by host material 9.In general, the transition that is added on the host material 9 is big more, and clamp voltage is just high more.It should be noted that also other protection from transients device also approaches clamp voltage in Fig. 5, just approach clamp voltage so soon not as host material 9.And the clamp voltage that these other devices approach might not have the size the same with Vc.
For conventional overload protection device among Fig. 5, discharge device demonstrates maximum overshoot, surpasses nearly 1,000 volt of clamp voltage.Secondly maximum overshoot is a rheostat, surpasses clamp voltage more than 400 volts.In contrast to this, the overshoot of host material 9 can be ignored.
Response EOS transition arrives the required time of clamp voltage, can be described as " clamping operation ", and can be determined with clamping operation by the protection effect that overcurrent device provides.In Fig. 5, the clamping operation of zener device is near 2 nanoseconds.Can see that host material 9 had than other protection device and material shorter clamping operation, thereby was more effective.About this respect of Fig. 5, should point out emphatically, as host material, same applied voltage is added on the conventional device, and those conventional devices of selecting for use, in fact as the device representative of using under the analogue.Thereby Fig. 5 shows the respective performances of the conventional device of comparing with host material 9.
Fig. 6 represents to be made of the host material according to invention, usually with the conductor lines 51 of the device protection of label 53 expressions.Conductor lines should be understood to any transmission of electric signals or electric power to the conductor that needs the EOS protecting network.In the embodiment that Fig. 6 represents, device 53 is that column host material cross section, a hollow garden is inserted between conductor lines 51 and the garden post shell, and garden post inner surface of outer cover and lead 51 contact, and the outer surface of garden cylindrical cross-section radially links to each other with ground.
About the working condition of device shown in Figure 6, under normal circumstances, conductor lines 51 transmits signals to a Circuits System to be protected.Under normal electrical potential difference between conductor lines 51 and the ground, the resistance of host material is very high, and the electric current that flows through host material can be ignored.Yet, disturbing owing to high energy EOS occurs, the voltage on the conductor lines 51 significantly increases, and the resistance of host material 9 just sharply reduces, and is enough to form to ground from conductor lines 51 bypass of an electricity.The electric current that flows through host material is owing to the electric current summation of passing through conductor 51 on the electric current of EOS interference and the effect owing to host material and ground short circuit.So host material 9 energy that bears is transition and the 51 energy summations that are dissipated that flow into materials from the electric system to the line.As long as the potential difference of conductor 51 surpasses the host material clamp voltage, by-pass current just constantly continues flowing.
Proceed from the reality, require the energy carried ability big more, the volume of required host material is also just big more aspect the EOS protection.If the product of protection is single microelectronic element, for example, the volume of required host material is very little.On the other hand, if a circuit to be protected comprises a huge antenna, so, required volume will be sizable.As a rule of design, according to host material of the present invention, every cubic centimetre of transmission approximate (10) or more Joule energy.But this ratio depends on the material of forming host material and remarkable change can be arranged.In fact, host material transmission 0.5 depends on the quality of host material to the energy of hundreds of joule.
Describe the working condition of host material now in detail.At first supposition the suitable host material 9 of quality be connected and electronic component to be protected or the conductor that is connected therewith between.Next supposes that high energy EOS transition occurs, and it threatens circuit to be protected.When host material was passed in transition, the very fast rising of the electric field that is associated with transient state also was applied on the material, and corresponding electric field also just raises and is applied on each particulate and in the material on the knot or potential barrier between each particulate.These electric fields cause several conductive mechanisms simultaneously, and various transport phenomena, after transition begins, may As time goes on play an important role.For example, electric current can flow through the host material 9 between the adjacent microparticles 11 or flow through knot between the adjacent semiconductor particulate 13, or the knot between adjacent semiconductor and the conductor.Therefore, need only the clamping level of EOS transient voltage greater than host material 9, many current paths are present in any part of host material along the interchain of particulate 11 and 13.
With regard to conductor particulate 11, electric field can not enter conductor microsome inside, and the electric field of these increases all is added to semiconductive particles and is added to tying of insulator.At conductor particulate 11 place of cusp is arranged, further increase electric field.Like this, enough hour of the resistance on the chain of adjacent conductor particulate 11, the electric current that flows through this chain meets the relation of conductor particulate Ohmic resistance rate and extra electric field intensity.
Can be interpreted as independent nonlinear resistive element to semiconductive particles 13.When electric field being applied on the semiconductive particles 9, the composition of semi-conducting material is arranged the change of single particulate conductivity, leads change so the electricity of chain that electric current flows through the semiconductive particles 13 of host material 9 is undertaken in domination.In other words, the number of semiconductive particles 13 and composition are determining the volume resistance of host material 9 usually.Be applied to the voltage drop on the barrier junction that constitutes by insulating material 15, must contribution be arranged the ON state volume resistance of host material 9.So total electricity of host material 9 is led directly the voltage drop string of the barrier junction that forms with conductor particulate 11, semiconductive particles 13 and by insulating material 15 and jointing material 19 and the summation that connects.
In Fig. 7, the voltage drop on the semiconductive particles 13 is expressed as V
SC, the voltage drop on the conductor particulate 11 is expressed as V
MAnd the voltage drop on the insulating material 15 that two particulates separate is expressed as V
B(barrier potential is poor) therefore, can be interpreted as Fig. 7 the chain (two particulate) of the host material 9 interior parts that explain through diagrams.Along total potential difference of this chain V just
SC, V
BWith V
MThree's sum.
Further with regard to Fig. 7, the overlay that people can notice insulating material 15 has point deformation at particulate 11 in abutting connection with the place of particulate 13.In fact, the mixture of particulate is in order to forming host material 9, or directly contacts semi-conducting material in another particulate because of unsuitable particulate overlay has caused conductor material in the direct contact semiconductor material of conductor material or the particulate directly to contact conductor material in another particulate or the semi-conducting material in particulate sometimes.Suchlike irregular, as long as they have suitable insulation situation, the characteristic of induced damage resistive host material 9 not just.
After being begun by the quantum tunneling electron transport, another transport mechanism begins to play a significant role, and for example, the thermionic emission of electronics almost occurs simultaneously with tunnelling.And, the electron transport effect can both appear by snowslide, Zener breakdown and field emission.Have under the situation that the transition of fast rise time produces in existence, the result that above-mentioned electron transport mode accumulates makes host material 9 have the nonlinear resistance property of height.
When the electric field that produces when the EOS transition reduces, between conductor particulate 11 and semiconductive particles 13, tie the energy barrier height, relatively increased with the electron energy of attempting to pass through this potential barrier and (in Fig. 7, tied energy barrier with V
BBe mark).As a result, in case the transition amplitude reduces, host material 9 just promptly is varied to, and the material of very big resistance is arranged, and the bypass effect of material also reduces rapidly.
A main purpose making host material 9 is to provide the unnumbered chain of being made up of adjacent microparticles, should be fully little along chain adjacent microparticles spaced apart distance, so that electronic energy transports by the insulating material 15 that separates particulate, played a major role at first by the quantum tunneling of electronics.In other words, insulating material 15 apart from spaced conductors particulate 11 and semiconductive particles 13, forms the knot between the particulate of chain or net with very little, strictly says, can be described as " tunnel junction ".For this purpose, can be defined as tunnel junction less than the spacing between the particulate of hundreds of dust.During extra electric field, electronics even tie the energy that the theoretic energy barrier that has is higher than some electronics at least, transports electric current but electronics still can pass potential barrier by insulating barrier 15 on tunnel junction.For above-mentioned characteristic is described, depend on the probability statistics model of electronic characteristic.It is because quantum tunneling works that said electronics passes potential barrier, and and the energy of unprovoked electronics surpass the height of potential barrier.Because producing tunnelling current almost takes place simultaneously with the electric field that applies above minimum value, so should believe, 9 response times of host material are because the result that the quantum tunneling of electronics transports very soon, when extra electric field is that effective barrier width high, insulating material 15 is enough thin, and semiconductive particles 13 is that quantum tunneling will occur under the little situation.In addition, the conduction that the transport phenomena that quantum tunneling compares increases is important to the response time aspect of host material 9 not only, but also has promoted the durability (promptly reduced to puncture and lost efficacy) of material.
In making the selection process of host material 9, the conductor particulate is that each ground is coated with by insulating material and applies, and is same, and semiconductive particles also each ground is coated with insulating material 15 and applies.(can think in the context of the present invention: the oxide layer that forms on the conductor particulate 11 is also included within the step of " coating ".) then, coated conductor particulate 11 mixes mutually with jointing material 19, again the semiconductive particles 13 that has applied is added in the mixture.(in this case, utilizing jointing material 19 also is a kind of suitable insulator, and conductor particulate 11 can be coated with by the mixture that has jointing material and apply.) determine that according to jointing material 19 perhaps the cured condition is necessary.When making host material 9, importantly mixed conductor particulate 11 and semiconductive particles 13 equably.Under the situation of inhomogeneous mixing, the many continuous conductors and the chain of semiconductive particles may extend to another surface from a surface of host material, have consequently damaged properties of materials.General in a section of host material 9, nearly 25 to more than 500 conductors and semiconductive particles separate two relative faces of host material.
Above though the situation that host material 9 is used to protect the EOS transition has only been described, this material also can be applicable to protect the speed-sensitive switch of high-power circuit.
Though described the present invention with most preferred embodiment, above-mentioned disclosure should not be interpreted as being only limited to this.Various changes and modification after the content of having read above-mentioned disclosure, undoubtedly will be obvious for the person of ordinary skill of the art.Therefore, the applicant attempts to illustrate that with belonging to claim all various embodiment are included among spirit of the present invention and the scope.
Claims (36)
1, a kind of nonlinear resistance material that electrical overstress protection is provided is as short as several nanoseconds or shorter electric transition to prevent the rise time, and said material comprises a kind of matrix that is formed by following mixture:
A) most particle size is approximately less than the conductor material particulate of the separation of hundreds of micron;
B) most particle size is approximately less than the semi-conducting material particulate of the separation of hundreds of micron;
C) be coated on the particulate of conductor material particulate and semi-conducting material, so that form particle chains in the substrate, along the spacing distance between the particulate of this chain on average approximately less than the hundreds of dust, to allow with the transition of high energy electricity, electronics produces the insulating material of significant non-linear conduction owing to quantum tunneling between particulate in said chain.
2, a kind of material according to claim 1 comprises that further said particulate is the jointing material that is suspended in equably wherein substantially.
3, a kind of material according to claim 1, the size of conductor material particulate wherein is approximately less than 100 microns.
4, a kind of material according to claim 3, the size range of semi-conducting material particulate wherein are approximately from 0.1 micron to 100 microns.
5, a kind of material according to claim 4, wherein less than the semiconductive particles number oversize far away of size range lower limit number greater than the semiconductive particles of range limit.
6, a kind of material according to claim 1, conductor particulate wherein comprises the carbonyl nickel particulate.
7, a kind of material according to claim 1, conductor particulate wherein comprises titanium carbide, nickel, tungsten carbide, boron carbide, zirconium carbide, carbon black, graphite, red copper, aluminium, molybdenum, silver, gold, zirconium, brass, cadmium, bronze, iron, tin, beryllium, lead, boride, ramet and mu-metal (Mu-metal), some materials in this group material.
8, a kind of material according to claim 5, the scope about 10 of conductor resistance rate wherein
-1To 10
-6Ohm/cm.
9, a kind of material according to claim 2, the percentage by weight of conductor particulate wherein be approximately greater than 1%, and approximately less than 45%.
10, a kind of material according to claim 2, jointing material wherein is an electrical insulator.
11, a kind of material according to claim 10, jointing material wherein is a polymer.
12, a kind of material according to claim 10, jointing material percentage by weight wherein are approximately greater than 10 (10%) of host material.
13, a kind of material according to claim 10, jointing material wherein is selected from thermosetting polymer, thermoplastic, this group material of rubber, mixture of polymers and admixture.
14, a kind of material according to claim 1, conductor particulate wherein has a plurality of cusps, strengthens with the field that forms between particulate.
15, a kind of material according to claim 1, insulating material wherein each be coated on each semiconductive particles.
16, a kind of material, insulating material wherein according to claim 15 comprise fuming silicon dioxide.
17, a kind of material according to claim 6, fuming wherein silicon dioxide comprise Cab-O-Sil.
18, a kind of material according to claim 1, the insulating material that coated fine particles is wherein used comprises: fuming silicon dioxide, kaolin, kaolinite, three aquation aluminium, feldspar, silica, bead, calcium carbonate, barium sulfate, calcium sulfate or the oil of multiple shape.
19, a kind of material according to claim 2, the electrical resistivity range of jointing material wherein is approximately from 10
-12To 10
-15Ohm/cm.
20, a kind of material, conductor particulate, semiconductive particles and insulating material wherein according to claim 1 be for the clamp voltage that reaches hundreds of volts selected.
21, a kind of in order to prevent that the preparing process that the rise time is as short as the nonlinear resistance material of several nanoseconds or shorter electric transition from comprising:
(a) the preparation particle size is generally less than the conductor material particulate and the semi-conducting material particulate of hundreds of micron;
(b) apply each conductor material particulate and each semi-conducting material particulate with insulating material;
The conductor material particulate that (c) will apply mixes mutually with the semi-conducting material particulate that applied, to form the matrix that unnumbered adjacent microparticles chain is arranged substantially uniformly, to allow that a large amount of electronics is with adding the overload transition, conducted electricity between particulate by quantum tunneling, particulate wherein is insulated a layer distance that separates and is no more than the hundreds of dust.
22, a kind of technology according to claim 21, wherein further comprise the jointing material that is added to suspended conductor and semi-conducting material particulate.
23, a kind of technology according to claim 21, the particle size of conductor material wherein is approximately less than 100 microns.
24, a kind of technology according to claim 23, the size range of semi-conducting material particulate wherein is from 0.1 micron to 100 microns.
25, a kind of technology according to claim 21, conductor wherein and semi-conducting material particulate are coated with insulating material respectively and apply before mixing.
26, a kind of technology according to claim 25, the coating wherein conductor material particulate of associating mixes with jointing material, and then with the mixture mutually fusion of semi-conducting material particulate with jointing material and conductor material particulate.
27, a kind of technology according to claim 21, conductor material particulate wherein comprises carbonyl nickel.
28, a kind of technology according to claim 21, this class material of conductor particulate wherein comprises: titanium carbide, nickel, tungsten carbide, boron carbide, zirconium carbide, carbon black, graphite, red copper, aluminium, molybdenum, silver, gold, zinc, brass, cadmium, bronze, iron, tin, beryllium, lead, boride, ramet or mu-metal (Mu-metal).
29, a kind of technology according to claim 22, the percentage by weight of conductor particulate in material wherein is approximately greater than 1%, approximately less than 45%.
30, a kind of technology according to claim 22, jointing material wherein is an electrical insulator.
31, a kind of technology according to claim 30, jointing material wherein is a polymer.
32, a kind of technology according to claim 30, the percentage by weight of jointing material wherein are approximately greater than 10 (10%) of host material
33, a kind of technology according to claim 21, insulating material wherein is coated on the semiconductive particles separately.
34, a kind of technology, insulating material wherein according to claim 33 comprise fuming silicon dioxide.
35, a kind of in order to prevent that the rise time is as short as the varistor of several nanoseconds or the transition of shorter electricity overload, this device comprises;
A) by the conductor material and the semi-conducting material particulate that separate, the matrix of the nonlinear resistance material of forming with the unordered mixture that is coated in the insulating material on the semiconductive particles for insulated conductor material and semi-conducting material particulate, chain at conductor material and semi-conducting material particulate, because spacing is small enough to allow that electronics transships transition with electricity, at said particulate intercropping quantum tunneling;
B) electrode be used for host material be connected electrically in and wait to protect between the electric installation of transient electrical overload.
36, a kind of device according to claim 31 further comprises, the particulate of said separation roughly evenly is suspended in the insulating adhesive material,
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN87105596A CN1030842A (en) | 1987-07-16 | 1987-07-16 | Electrical overstress protection material and technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN87105596A CN1030842A (en) | 1987-07-16 | 1987-07-16 | Electrical overstress protection material and technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1030842A true CN1030842A (en) | 1989-02-01 |
Family
ID=4815381
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN87105596A Pending CN1030842A (en) | 1987-07-16 | 1987-07-16 | Electrical overstress protection material and technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1030842A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101071666B (en) * | 2007-06-22 | 2010-06-09 | 赑丰生技股份有限公司 | Low-capacitance layered wafer rheostat and overvoltage protection material thereof |
| CN101105993B (en) * | 2007-06-22 | 2011-08-10 | 赑丰生技股份有限公司 | Surge absorber material and method for manufacturing surge absorber by the material |
| CN105789420A (en) * | 2014-12-17 | 2016-07-20 | 黄文武 | LED (Light-Emitting Diode) ceramic substrate |
| CN110357634A (en) * | 2019-07-10 | 2019-10-22 | 中国科学院上海硅酸盐研究所 | A kind of application of boron carbide ceramics as pressure-sensitive ceramic material |
-
1987
- 1987-07-16 CN CN87105596A patent/CN1030842A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101071666B (en) * | 2007-06-22 | 2010-06-09 | 赑丰生技股份有限公司 | Low-capacitance layered wafer rheostat and overvoltage protection material thereof |
| CN101105993B (en) * | 2007-06-22 | 2011-08-10 | 赑丰生技股份有限公司 | Surge absorber material and method for manufacturing surge absorber by the material |
| CN105789420A (en) * | 2014-12-17 | 2016-07-20 | 黄文武 | LED (Light-Emitting Diode) ceramic substrate |
| CN110357634A (en) * | 2019-07-10 | 2019-10-22 | 中国科学院上海硅酸盐研究所 | A kind of application of boron carbide ceramics as pressure-sensitive ceramic material |
| CN110357634B (en) * | 2019-07-10 | 2021-08-31 | 中国科学院上海硅酸盐研究所 | Application of boron carbide ceramic as voltage-sensitive ceramic material |
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