CN100472674C - Overcurrent protection component - Google Patents
Overcurrent protection component Download PDFInfo
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- CN100472674C CN100472674C CNB2005100931625A CN200510093162A CN100472674C CN 100472674 C CN100472674 C CN 100472674C CN B2005100931625 A CNB2005100931625 A CN B2005100931625A CN 200510093162 A CN200510093162 A CN 200510093162A CN 100472674 C CN100472674 C CN 100472674C
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- over
- protecting element
- current protecting
- element according
- ptc layer
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Abstract
The over current protection component includes two pieces of metal foil, and a material layer with Positive Temperature Coefficient (PTC). Being between two pieces of metal foil, the PTC material layer includes multiple crystalline high molecular polymers, a conducting ceramic stuffing and a non-conducting stuffing. Grain size of the said conducting ceramic stuffing possesses a specific distribution. Volume resistance of the said PTC material layer is smaller than 0.1 ohm /cm.
Description
Technical field
The present invention relates to a kind of over-current protecting element; more specifically; the over-current protecting element that relates to a kind of PTC of having conducing composite material, described over-current protecting element have preferred volume resistance value and resistance reproducibility, are particularly suitable for the power protection of mobile communication equipment.
Background technology
Owing to have positive temperature coefficient (Positive Temperature Coefficient; PTC) resistance of the conducing composite material of characteristic has the sharp characteristic of variations in temperature reaction, can be used as the material of current sensing element, and has been widely used on over-current protecting element or the circuit element at present.Because the resistance of PTC conducing composite material under normal temperature can be kept utmost point low value, makes circuit or battery be able to normal operation.But when circuit or battery generation overcurrent (over-current) or when crossing the phenomenon of high temperature (over-temperature), its resistance value can be brought up to a high resistance state (at least 10 moment
4More than ohm), and with excessive current reversal payment, to reach the purpose of protection battery or circuit element.
Generally speaking, the PTC conducing composite material has crystalline polymer by one or more and conductive filler is formed, and described conductive filler is scattered in the described polymer equably.Described polymer is generally polyolefin polymers, for example: polyethylene.And conductive filler is generally carbon black, metallic particles or anaerobic ceramic powders, for example: titanium carbide or tungsten carbide etc.
The electrical conductivity of described conducing composite material is decided on the kind and the content of conductive filler.Generally speaking, because the black carbon surface concave-convex surface is better with the tack of polyolefin polymers, so have resistance reproducibility preferably.Yet the electrical conductivity that carbon black can provide is lower than metallic particles, and metallic particles proportion is bigger, disperses more inhomogeneous and easily oxidized and cause resistance to raise.For effectively reducing the resistance value of over-current protecting element and avoiding oxidation, tend to gradually with the conductive filler of ceramic powders as the low resistance conducing composite material.But because ceramic powders has convex-concave surface unlike carbon black, with the tack of polymer such as TPO than carbon black difference, so the also difficult control of its resistance reproducibility.For increasing the tack between polyolefin polymers and the metallic particles, the conducing composite material that with the ceramic powders is conductive filler routinely can add a couplant in addition, for example: compound anhydride or silane compound, with the tack between reinforcement polyolefin polymers and the metallic particles, yet but can't reduce whole resistance value effectively after adding couplant.
The PTC conducing composite material of low resistance (about 20m Ω) of having on the market at present be with nickel (Ni) as conductive filler, its voltage that can bear is 6V only.Wherein, if nickel is protected and air insulation without tight, oxidation easily after a period of time so causes resistance to rise.In addition, described conducing composite material is through triggering (trip) afterwards, and its resistance reproducibility is bad.
Summary of the invention
Main purpose of the present invention provides a kind of over-current protecting element; have conductive filler and the low-melting crystalline polymer polymer of at least one tool that specified particle diameter distributes by adding one, and make described over-current protecting element have defencive function, voltage-resistent characteristic and the resistance reproducibility of excellent low-resistance value, low temperature rapid triggering (trip).
In order to achieve the above object, the present invention discloses a kind of over-current protecting element, and it comprises two tinsels and a ptc layer.Described tinsel contains the outstanding rough surface of warty (nodule), and contacts with described ptc layer direct physical.Described ptc layer is between described two tinsels and comprises a plurality of crystalline polymer polymer, an anaerobic conductivity ceramics powder (that is conductive filler) and a non-conducting filler.The particle size of described anaerobic conductivity ceramics powder is between 0.01 μ m to 30 μ m, the preferable particle size size is between 0.1 μ m to 10 μ m, the volume resistance value of described anaerobic conductivity ceramics powder is less than 500 μ Ω-cm, and is dispersed among described a plurality of crystalline polymer polymer.Described a plurality of crystalline polymer polymer can be selected from: high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene, polyvinyl fluoride and co-polymer thereof.In order to reach the defencive function of low temperature rapid triggering (trip), comprise the crystalline polymer polymer that a fusing point is lower than 115 ℃ in the described ptc layer at least.
For the safety of protecting lithium ion battery to overcharge; the over-current protecting element that is used in lithium ion battery must just can produce triggering (trip) reaction at lower temperature; therefore ptc layer is selected more low-melting macromolecular material for use: as low density polyethylene (LDPE); and can select one or more polymeric materials for use, but the minimum fusing point in each polymer must be lower than 115 ℃.Described low density polyethylene (LDPE) can form with traditional Z iegler-Natta catalyst or with the Metallocene polymerization catalyst, also can form via vinyl monomer and other monomer (for example: butylene (butene), hexene (hexene), octene (octene), acrylic acid (acrylic acid) or vinylacetate (vinyl acetate)) combined polymerization.
Anaerobic conductivity ceramics powder used in the present invention is selected from (1) metal carbides (for example: titanium carbide (TiC), tungsten carbide (WC), vanadium carbide (VC), zirconium carbide (ZrC), niobium carbide (NbC), ramet (TaC), molybdenum carbide (MoC) and hafnium carbide (HfC)); (2) metal boride (for example: titanium boride (TiB
2), vanadium boride (VB
2), zirconium boride (ZrB
2), niobium (Nb) boride (NbB
2), molybdenum boride (MoB
2) and hafnium boride (HfB
2)); Or (3) metal nitride (for example: zirconium nitride (ZrN)).
The shape of anaerobic conductivity ceramics powder used in the present invention can present the particle of multiple different patterns, for example: ball-shape (spherical), square build (cubic), sheet type (flake), multiangular or column type etc.Generally speaking, because of the hardness of conductivity ceramics powder is quite high, manufacture method is different from carbon black or metal dust, so that its shape also is different from the metal dust of carbon black or some high structures (high structure).The shape of anaerobic conductivity ceramics powder particle is that its particle diameter is less than 10 μ m based on low structural type (low structure), and aspect ratio (aspect ratio) is less than 10.
Non-conducting filler used in the present invention is selected from the inorganic compound with flame retardant effect or arc resistant effect, for example: zinc oxide, antimony oxide, aluminium oxide, silica, calcium carbonate, magnesium sulfate, barium sulfate and the compound (for example: magnesium hydroxide, aluminium hydroxide, calcium hydroxide, barium hydroxide etc.) that contains hydroxy (OH).Its particle size of this non-conducting filler is mainly between 0.05 μ m to 50 μ m, and its weight ratio is between 1% to 20%.
Since anaerobic conductivity ceramics powder volume resistance value very low (less than 500 μ Ω-cm) so that composite ptc material can reach the volume resistance value that is lower than 0.5 Ω-cm.Generally speaking; ptc material is difficult for reaching the volume resistance value that is lower than 0.1 Ω-cm; even when ptc material can reach the volume resistance value that is lower than 0.1 Ω-cm; regular meeting is because of the too low characteristic that loses proof voltage of resistance, yet the ptc layer in the over-current protecting element of the present invention can be less than 0.1 Ω-cm and can bear the voltage of 12V to 40V and smaller or equal to 50 amperes electric current.
Generally speaking, when ptc material reaches the volume resistance value that is lower than 0.1 Ω-cm, Chang Wufa bears the voltage that is higher than 12V, therefore the present invention is in order to promote proof voltage, add non-conducting filler in the ptc material, mainly containing the inorganic compound of hydroxy (OH), and the thickness of control ptc layer makes described low-resistance P TC material can significantly promote the voltage that can bear greater than 0.2mm.The non-conducting filler of this inorganic compound also has the function of controlling resistance reproducibility, usually can be with resistance reproducibility ratio (trip jump) R
1/ R
iBe controlled at less than 3.R wherein
iBe initial resistance, R
1For being returned to room temperature measured resistance after a hour after triggering once.
Because ptc layer has quite low volume resistance value, so the area of PTC chip (that is the required ptc layer of over-current protecting element of the present invention) can be narrowed down to less than 50mm
2, and still can reach the low-resistance purpose of element, finally can production cost be reduced from producing more PTC chip with every ptc layer of area.
Over-current protecting element of the present invention; wherein said two tinsels can with two other metallic nickel sheet (promptly; metal electrode film) is bonded into an assembly (assembly) by tin cream (solder) through reflow or by the spot welding mode, normally becomes the element of an axial lead type (axial-leaded), radial lead type (radial-leaded), terminal type (terminal) or surface adhesion type (surface mount).Over-current protecting element of the present invention; wherein said tinsel up and down can be connected in power supply and form a galvanic circle (circuit) (in another embodiment; then can be connected in power supply and form a galvanic circle) by described two metal electrode films; ptc layer operates under the situation of overcurrent, and reaches the function in protection loop.
Description of drawings
Fig. 1 illustration over-current protecting element of the present invention; And
Another embodiment of Fig. 2 illustration over-current protecting element of the present invention.
Embodiment
The two kinds of compositions (embodiment one and embodiment two) and the manufacturing process of over-current protecting element of the present invention below are described.
The composition of the employed ptc layer of over-current protecting element of the present invention and weight (unit: g) as shown in Table 1.
Table one
| LDPE-1 | HDPE-1 | HDPE-2 | Mg(OH) 2 | TiC | |
| Embodiment one | 12.66 | 0.50 | ---- | 5.04 | 92.60 |
| Embodiment two | 11.20 | ---- | ---- | 5.04 | 93.60 |
| Comparative example | ---- | 3.16 | 12.65 | 4.20 | 90.90 |
Wherein LDPE-1 is a low-density crystallinity polyethylene (density: 0.924g/cm
3, fusing point: 113 ℃); HDPE-1 is a high density crystallinity polyethylene (density: 0.943g/cm
3, fusing point: 125 ℃); HDPE-2 is a high density crystallinity polyethylene (density: 0.962g/cm
3, fusing point: 131 ℃); Mg (OH)
2For with the magnesium hydroxide of 96.9wt% purity and contain 0.50% CaO, 0.85% SO
3, 0.13% SiO
2, 0.03%Fe
2O
3, 0.06% Al
2O
3Deng minor compound and titanium carbide (TiC) conductive filler.Wherein the average grain diameter size of titanium carbide (TiC) is 3 μ m, and particle diameter aspect ratio (aspect ratio) is less than 10.
Manufacturing process is as follows: will criticize formula mixing roll (Hakke-600) feeding temperature and fix on 160 ℃, feed time is 2 minutes, the charging program is for pressing the weight shown in the table 1, add quantitative crystalline polymer polymer, stirred for several second, add anaerobic conductivity ceramics powder (titanium carbide, its particle size is between 0.1 μ m to 10 μ m) and non-conducting filler again.The rotating speed of mixing roll rotation is 40rpm.After 3 minutes, its rotating speed is brought up to 70rpm, continue blanking after mixing 7 minutes, and form a conducing composite material with ptc characteristics.
It is steel plate that above-mentioned conducing composite material is inserted skin with symmetric mode up and down, and interior thickness is in the mould of 0.35mm, and mould is respectively put the not imperial release cloth of one deck iron, first precompressed 3 minutes, precompressed operating pressure 50kg/cm up and down
2, temperature is 180 ℃.Carry out pressing after the exhaust, pressing time is 3 minutes, and pressing pressure is controlled at 100kg/cm
2, temperature is 180 ℃, repeats the one step press action afterwards again, and pressing time is 3 minutes, and pressing pressure is controlled at 150kg/cm
2, temperature is 180 ℃, forms a ptc layer 11 (referring to Fig. 1) afterwards.The thickness of described ptc layer 11 is 0.35mm or 0.45mm.
Described ptc layer 11 is cut into 20 x 20cm
2Square, utilize pressing that two tinsel 12 direct physical are contacted with the upper and lower surface of described ptc layer 11 again, it covers tinsel 12 in described ptc layer 11 surfaces in regular turn with symmetric mode up and down.Described tinsel 12 contains the outstanding rough surface of warty (nodule) and contacts with ptc layer 11 direct physical.Pressing dedicated buffering material, the not imperial release cloth of iron and steel plate and form a sandwich construction.Described sandwich construction carries out pressing again, and pressing time is 3 minutes, and operating pressure is 70kg/cm
2, temperature is 180 ℃.Afterwards; shaped like chips over-current protecting element 10 with mould die-cut formation 3.4mm x 4.1mm or 3.5mm x 6.5mm; again two metal electrode films 22 are connected in up and down on described two tinsels 12 by the reflow mode with tin cream (solder paste), make the current protection element 20 (ginseng Fig. 2) of a shape formula.
In addition, the volume resistance value (ρ) of described ptc layer 11 can be calculated according to formula (1) and get:
Wherein R is the resistance value (Ω) of ptc layer 11, and A is the area (cm of ptc layer 11
2), L is the thickness (cm) of ptc layer 11.With Ri (Ω) value (0.0069 Ω) substitution with table 2 of the R in the formula (1), A is with 6.5 x 3.5mm
2(=6.5 x 3.5 x 10
-2Cm
2) substitution, (=0.045cm) substitution can be tried to achieve ρ=0.0349 Ω-cm to L, is significantly less than 0.1 Ω-cm with 0.45mm.
The current protection element 20 of axle shape formula placed under 80 ℃ the ambient temperature; voltage and testing current through 6V/0.8A; situation when battery is warming up to 80 ℃ under 6V/0.8A overcharges environment with imitation; the current protection element 20 of described axle shape formula must can trigger so that cut-off current, to reach the purpose of protecting battery.
Table 2 shows that embodiment one and embodiment two all can trigger, and can reach the purpose of protection battery; Yet comparative example but can't trigger, thereby can't reach the purpose of protection battery.In addition, the current protection element 20 of axle shape formula is also shown in the table 2 in the surface temperature that (that is, under overcurrent protection triggering state) under the voltage of 6V, 12V and 16V triggers.Wherein, the surface temperature of comparative example surpasses 100 ℃, than the surface temperature high at least 10 ℃ (surface temperature of embodiment two all is lower than 100 ℃) of embodiment two.Therefore the over-current protecting element among the embodiment two can trigger at lower temperature, and is rapider than comparative example to the reaction of temperature, and because of using conductivity ceramics powder, its initial resistance (R
i) less than 0.010 Ω.
Table two
Over-current protecting element of the present invention; have conductive filler and at least one crystalline polymer polymer that specified particle diameter distributes by adding one with low melting point (below 115 ℃); via the result of table 2 as can be known, over-current protecting element of the present invention can reach really and have excellent initial resistance value (R
iLess than 20m Ω), the intended purposes of defencive function, voltage-resistent characteristic and the resistance reproducibility of low temperature (80 ℃) rapid triggering.
Technology contents of the present invention and technical characterstic are above being disclosed, yet one of ordinary skill in the art still may make all substituting and revising of spirit of the present invention that do not deviate from based on teaching of the present invention and announcement.Therefore, protection scope of the present invention should be not limited to the content that embodiment discloses, and should comprise various of the present invention the substituting and correction of not deviating from, and is contained by the aforesaid right claim.
Claims (17)
1. over-current protecting element is characterized in that comprising:
Two tinsels; And
One ptc layer, its be stacked between described two tinsels and the volume resistance value less than 0.1 Ω-cm, it comprises:
(i) a plurality of crystalline polymer polymer, it comprises the crystalline polymer polymer that at least one fusing point is lower than 115 ℃;
To between the 10 μ m, the volume resistance value is less than 500 μ Ω-cm between 0.1 μ m for a (ii) anaerobic conductivity ceramics powder, its particle size, and intersperses among among the described crystalline polymer polymer; And
A (iii) non-conducting filler.
2. over-current protecting element according to claim 1, the thickness that it is characterized in that described ptc layer is greater than 0.2mm.
3. over-current protecting element according to claim 1, the initial resistance value that it is characterized in that described ptc layer is less than 20m Ω.
4. over-current protecting element according to claim 1 is characterized in that the voltage that described ptc layer can bear is smaller or equal to 40 volts.
5. over-current protecting element according to claim 1, the area that it is characterized in that described ptc layer is less than 50mm
2
6. over-current protecting element according to claim 1 is characterized in that under overcurrent protection triggering state, its surface temperature is lower than 100 ℃.
7. over-current protecting element according to claim 1 is characterized in that resistance reproducibility ratio is less than 3.
8. over-current protecting element according to claim 1 is characterized in that described anaerobic conductivity ceramics powder is a titanium carbide.
9. over-current protecting element according to claim 1 is characterized in that it is a low density polyethylene (LDPE) that described fusing point is lower than 115 ℃ crystalline polymer polymer.
10. over-current protecting element according to claim 9 is characterized in that described low density polyethylene (LDPE) is to be formed by polymerization catalyst.
11. over-current protecting element according to claim 1 is characterised in that wherein stating non-conducting filler is one to contain the inorganic compound of hydroxy (OH).
12. over-current protecting element according to claim 11 is characterized in that described inorganic compound is a magnesium hydroxide.
13. over-current protecting element according to claim 1 is characterized in that described two tinsels contain the outstanding rough surface of warty and contact with described ptc layer direct physical.
14. over-current protecting element according to claim 1 is characterized in that comprising in addition two metal electrode films, itself and described two tinsels are bonded into an assembly.
15. over-current protecting element according to claim 1 is characterized in that described two tinsels can be connected in power supply and form a galvanic circle.
16. over-current protecting element according to claim 14 is characterized in that described two metal electrode films can be connected in power supply and form a galvanic circle.
17. over-current protecting element according to claim 1 is characterized in that the electric current that bears is smaller or equal to 50 amperes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100931625A CN100472674C (en) | 2005-08-19 | 2005-08-19 | Overcurrent protection component |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100931625A CN100472674C (en) | 2005-08-19 | 2005-08-19 | Overcurrent protection component |
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|---|---|
| CN1917101A CN1917101A (en) | 2007-02-21 |
| CN100472674C true CN100472674C (en) | 2009-03-25 |
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|---|---|---|---|
| CNB2005100931625A Expired - Fee Related CN100472674C (en) | 2005-08-19 | 2005-08-19 | Overcurrent protection component |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101728039B (en) * | 2009-12-31 | 2016-02-24 | 上海长园维安电子线路保护有限公司 | Over-current protecting element |
| CN102237164B (en) * | 2010-04-26 | 2015-11-25 | 聚鼎科技股份有限公司 | Over-current protecting element |
| CN114230894B (en) * | 2021-12-20 | 2022-10-04 | 东莞市贝特电子科技股份有限公司 | Manufacturing method for improving voltage resistance of PPTC product with ultralow resistance value |
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