201120922 六、發明說明： 【發明所屬之技術領域】 本發明係有關一種高分子熱敏電阻電流承载率之提 升方法’目的在降低整體PPTC熱敏電阻之電阻，以提升 PPTC熱敏電阻之電流承载奉。 【先前技術】 為防止電路發生過電流(oveivcurrent)或是過高溫 • (over-temperature)現象的過電流保護元件，隨著目前可攜式 電子產品（例如手機、筆記型電腦、手提攝影機及個人數 位助理器等）的廣泛應用，其重要性也愈來愈顯著。 一般利用正溫度係數之導電性高分子聚合物(p〇lymer Positive Temperature Coefficient，PPTC)材料所製作之高分 子正溫度係數熱敏電阻元件（以下稱PPTC熱敏電阻）之電阻 值對溫度變化的反應相當敏銳，在PPTC熱敏電阻於正常使 用狀況時，其電阻可維持極低值，使電路得以正常運作。 • 但是’當發生過電流或過高溫的現象而使溫度上升至一臨 界溫度時，其電阻值會瞬間彈跳至一高電阻狀態（例如1〇4 ohm以上），而將過量之電流反向抵銷，以達到保護電池或 電路元件之目的。因此，該PPTC熱敏電阻已見整合於各式 電路元件中，以防止過電流的損害。 習知之過電流保護裝置10的結構如第一圖所示，其包 含一電流感測層11、兩内電極層12、兩絕緣層14、兩防焊 漆層15及兩外電極層16。該兩内電極層12分置於該電流感 測層11之上、下表面以形成一類似三明治結構之電流感測 201120922 元件13。由於該電流感測層11包含PPTC材料，因此該電流 感測元件13係可為PPTC熱敏電阻。該絕緣層14分別設置於 該電流感測元件13之上、下表面’作為導熱及絕緣之用。 該防焊漆層15及外電極層16設於該絕緣層14之表面，分別 作為與外部電路板焊接時之防焊及黏著墊片。 PPTC熱敏電阻係由導電填充材（一般為碳黑、金屬粉 末、導電性粒子等等）、高分子材料、以及添加劑等所組成， 該導電填充材均勻分散在絕緣性的高分子材料中形成導電 鏈，而成為一導電（低阻抗)狀態，而發生過電流或過高溫 的現象而使溫度上升至一臨界溫度時，例如聚合物熔點 (melting point)附近，因為結晶性高分子材料熔融時產生劇 烈的體積膨脹導致導電鏈被打斷而形成一絕緣（高阻抗）狀 態，以阻斷電流，藉以保護電路或元件，而當溫度或電流 的狀況解除後，元件電阻抗值恢復到原先之低阻抗狀態， 是以高分子正溫度係數熱敏電阻元件亦可稱為“可回復式 元件”’即高分子聚合物切換開關之意，主要用於小功率電 子設備的短路及過電流保護。 其中，該PPTC熱敏電阻要提高其電流承載率唯一之 方式是降低電阻，而電阻之關係式為R = pL/A(p為電阻係 數，L為元件的長度，a為元件的截面積），故要降低電阻 可以有幾種方式：（1)降低PPTC之電阻係數；（2)降低PPTC 熱敏電阻之長度；（3)增加ppTc熱敏電阻之截面積；而關 於PPTC熱敏電阻之長度及截面積部份，一來可降低長度 之範圍有限，無法大為降低電阻，二來增加截面積勢必增 加整體PPTC熱敏電阻之體積違反輕薄短小之產品要求， 201120922 故較佳的方式只能藉由降低PPTC熱敏電阻之電隊係麩來 降低整體PPTC熱敏電阻之電阻。 一般而言，PPTC熱敏電阻中所含有之碳黑其表命奚 凹凸狀，與聚烯烴類聚合物的附著性較佳，所以具有隹的 電阻再現性。然而，碳黑所能提供的導電度較金屬賴雜你’ 而金屬顆粒比重較大’分散較不均勻且易被氧化而造成’ 阻升高。為有效降低過電流保護元件的電阻值且避免氧 化，逐漸趨向以陶瓷粉末作為低阻值導電複合材料之導電 籲 填料。但由於陶瓷粉末不似碳黑具有凹凸表面，與聚烯烴 類等聚合物的附著性較碳黑差，所以其電阻再現性也較難 控制。為增加聚婦烴類聚合物及金屬顆粒之間的附著性， 習知以陶竟粉末為導電填料之.導電複合材料會另添加·一偶 合劑（coupling agent)’例如：酐類化1合物或是矽炫類化合 物（silanes) ’以加強聚烯烴類聚合物與金屬顆粒之間的附著 性’然而加入偶合劑後卻不能有效地降低整體之電阻值。 1 【發明内容】 本發明之主要目的即在提供一種高分子熱敏電阻電 流承載率之提升方法，目的在降低整體PPTC熱敏電阻之電 阻’以提升PPTC熱敏電阻之電流承載率。 為達上揭目的，本發明係於pptc熱敏電阻組成物中 另外添加石墨烯（graphene)或奈米碳管，而該石墨烯或奈 米碳管之重量百分比係小於或等於、纟且成物之1 〇 wt%，由該 石墨烯較為優異之導電特性，以大為降低整體PPTC熱敏 電阻之電阻，以增加PPTC熱敏電阻之電流承載率。 201120922 【實施方式】 本發明之特點，可參閱本案圖式及實施例之詳細說明 而獲得清楚地瞭解。 本發明「高分子熱敏電阻電流承載率之提升方法」， 至少包含有下列步驟： 步驟a、提供石墨烯或奈米碳管，可控制石墨烯或奈 米碳管表面官能基之數目，來調整與樹脂的相容性，例如： 若欲與極性樹脂相容，該石墨烯表面所具有之官能基數目 較多’若欲與非極性樹脂相容，該石墨烯表面所具有之官 能基數目較少；或者該石墨烯可進一步經由回火來產生導 電級的石墨烯；而該一般級或導電級的石墨烯可以形成母粒 (masterbatch)或粉體(dry power)形式； 步驟b、將石墨烯或奈米碳管與樹脂混合以形成石墨 烯母粒或奈求碳管母粒，而該石墨烯或奈米碳管與樹脂之 混合比例為1 : 20 ’其中該樹脂可以為非極性之高密度聚 乙烯(HDPE); 步驟c、於混合完成之石墨烯或奈米礙管與樹脂中加 入•黑’則完成PPTC熱敏電阻組成物，其中該碳專之重 量百分比係為組成物之50〜60%，而該石墨稀之重量百分比 係小於或等於組成物之10%。 另一方法係於步驟a中提供粉體形式之石墨烯或奈米 碳管，再直接與樹脂及碳黑混合則完成pPTC熱敏電阻組 成物。 而在適當溫度下將該PPTC熱敏電阻組成物混煉 201120922 (compouriding)後經雙螺桿壓出機壓出製作呈連續式片狀 (sheet)、利用上下兩金屬箔板（一般為鎳板、鍍鎳銅板或鎳 銅合金）加熱壓合（lamination)成三明治的片狀組成物，再 經過各式後加工技術而形成上述具有金屬箔板的兩上下電 極的PPTC熱敏電阻元件。該ppTC熱敏電阻元件可製作成 單層PPTC熱敏電阻元件，亦可形成類似印刷電路板的雙 層或多層的堆疊(stack)封装方式來達到多層PPTC熱敏電 阻。 值得一提的是，本發明相較於習有熱敏電阻係具有下 列優點： 1、 藉由石墨烯或奈米碳管較為優異之導電特性，大為 降低整體PPTC熱敏電阻之電阻係數，於相同電阻長度(l) 及截面積(A)條件之下（R=pl/A)，該電阻係數(p)降低時， 則電阻(R)亦降低，可提高PPTC熱敏電阻之電流承載率。 2、 隨著碳黑的體積電阻降低，碳黑的添加量（1〇ading) 可以询時降低’可增加現有組成物配方的流動性，及碳黑 於樹脂中的分散性，與均勻性，並降低產品不良率。 3、 可依照樹脂之極性來控制石墨烯或奈米碳管表面官 能基之數目，以調整與不同樹脂的相容性。 4、 藉由簡單回火步驟則可產生導電級石墨稀或夺米碳 皆與且此回火步驟製成的，，導電級，，石墨埽或奈求碳管相較 匕：還原法（cheimcaUy reduced)製成的導電級石墨稀，導電 度兩10倍。 可進—步同時增加電子元件的截面積作法，以同時 降低電子元件的電阻，以提高電子元件的電流承载率。 201120922 6、不需要改變既有產品設計、既有製程、與後續加工， 與現有製程相容(compatible)。 本發明之技術内容及技術特點已揭示如上，然而熟悉 本項技術之人士仍可能基於本發明之揭示而作各種不背離 本案發明精神之替換及修飾。因此，本發明之保護範圍應 不限於實施例所揭示者，而應包括各種不背離本發明之替 換及修飾，並為以下之申請專利範圍所涵蓋。 【圖式簡單說明】 第一圖為一般過電流保護裝置之結構示意圖。 【主要元件符號說明】 過電流保護裝置10 電流感測層11 内電極層12 電流感測元件13 絕緣層14 防焊漆層15 外電極層16201120922 VI. Description of the Invention: [Technical Field] The present invention relates to a method for improving the current carrying capacity of a polymer thermistor, which aims to reduce the resistance of the overall PPTC thermistor to improve the current carrying of the PPTC thermistor Feng. [Prior Art] Overcurrent protection components to prevent over-current (over-temperature) or over-temperature (over-temperature) of the circuit, with current portable electronic products (such as mobile phones, notebook computers, portable cameras, and individuals) The widespread use of digital assistants, etc., is becoming more and more important. Generally, a resistance value of a polymer positive temperature coefficient thermistor element (hereinafter referred to as a PPTC thermistor) made of a positive temperature coefficient conductive polymer polymer (PPTC) material is used for temperature change. The response is quite sensitive. When the PPTC thermistor is in normal use, its resistance can be kept at a very low value, allowing the circuit to operate normally. • However, when an overcurrent or overheating occurs and the temperature rises to a critical temperature, the resistance value will instantaneously bounce to a high resistance state (for example, 1〇4 ohm or more), and the excess current will be reversed. Pin for the purpose of protecting the battery or circuit components. Therefore, the PPTC thermistor has been integrated into various circuit components to prevent damage from overcurrent. The structure of the conventional overcurrent protection device 10 is as shown in the first figure, and includes a current sensing layer 11, two internal electrode layers 12, two insulating layers 14, two solder resist layers 15, and two outer electrode layers 16. The two inner electrode layers 12 are placed on the lower surface of the current sensing layer 11 to form a sandwich-like current sensing 201120922 element 13. Since the current sensing layer 11 contains a PPTC material, the current sensing element 13 can be a PPTC thermistor. The insulating layer 14 is disposed on the upper surface and the lower surface of the current sensing element 13 for heat conduction and insulation. The solder resist layer 15 and the outer electrode layer 16 are provided on the surface of the insulating layer 14 as solder resist and adhesive pads when soldered to an external circuit board. The PPTC thermistor is composed of a conductive filler (generally carbon black, metal powder, conductive particles, etc.), a polymer material, and an additive, and the conductive filler is uniformly dispersed in an insulating polymer material. Conductive chain, which becomes a conductive (low-impedance) state, and an overcurrent or over-temperature phenomenon occurs to raise the temperature to a critical temperature, such as near the melting point of the polymer, because the crystalline polymer material melts. The violent volume expansion causes the conductive chain to be broken to form an insulating (high-impedance) state to block the current, thereby protecting the circuit or component, and when the temperature or current condition is removed, the component electrical resistance value is restored to the original state. In the low-impedance state, the polymer positive temperature coefficient thermistor element can also be called “recoverable element”, that is, the polymer polymer switch, which is mainly used for short-circuit and over-current protection of low-power electronic equipment. Among them, the only way to increase the current carrying capacity of the PPTC thermistor is to reduce the resistance, and the relationship of the resistance is R = pL/A (p is the resistivity, L is the length of the component, a is the cross-sectional area of the component) Therefore, there are several ways to reduce the resistance: (1) reduce the resistivity of the PPTC; (2) reduce the length of the PPTC thermistor; (3) increase the cross-sectional area of the ppTc thermistor; and regarding the PPTC thermistor The length and cross-sectional area can be reduced in a limited range, which can not greatly reduce the resistance. Secondly, increasing the cross-sectional area will increase the volume of the overall PPTC thermistor in violation of the light and short product requirements. 201120922 The resistance of the overall PPTC thermistor can be reduced by reducing the bristle of the PPTC thermistor. In general, the carbon black contained in the PPTC thermistor has an uneven appearance and excellent adhesion to a polyolefin-based polymer, and therefore has electrical resistance reproducibility. However, carbon black can provide a higher conductivity than metal, and the metal particles have a larger specific gravity, and the dispersion is less uniform and oxidized to cause an increase in resistance. In order to effectively reduce the resistance value of the overcurrent protection component and avoid oxidation, ceramic powder is gradually used as a conductive filler for the low resistance conductive composite. However, since the ceramic powder does not have a concave-convex surface like carbon black, and the adhesion to a polymer such as a polyolefin is inferior to that of carbon black, resistance reproducibility is also difficult to control. In order to increase the adhesion between the polycondensate polymer and the metal particles, it is known that the ceramic powder is used as a conductive filler. The conductive composite material is additionally added with a coupling agent', for example: an anhydride type 1 The substance or silanes 'to enhance the adhesion between the polyolefin polymer and the metal particles', however, the addition of the coupling agent does not effectively reduce the overall resistance value. SUMMARY OF THE INVENTION The main object of the present invention is to provide a method for improving the current carrying capacity of a polymer thermistor, aiming at reducing the resistance of the overall PPTC thermistor to increase the current carrying capacity of the PPTC thermistor. In order to achieve the above object, the present invention additionally adds graphene or carbon nanotubes to the pptc thermistor composition, and the weight percentage of the graphene or carbon nanotubes is less than or equal to, and is The material has a conductivity of 1% 〇wt%, which greatly reduces the resistance of the overall PPTC thermistor to increase the current carrying capacity of the PPTC thermistor. 201120922 [Embodiment] The features of the present invention can be clearly understood by referring to the detailed description of the drawings and the embodiments. The method for improving the current carrying capacity of a polymer thermistor comprises the following steps: Step a: providing a graphene or a carbon nanotube, which can control the number of surface functional groups of graphene or carbon nanotubes, Adjust the compatibility with the resin, for example: If it is to be compatible with the polar resin, the graphene surface has a large number of functional groups. 'If there is a compatibility with the non-polar resin, the number of functional groups on the graphene surface Less; or the graphene may further generate conductive grade graphene via tempering; and the general or conductive grade graphene may form a masterbatch or dry power form; step b, Graphene or carbon nanotubes are mixed with a resin to form a graphene masterbatch or a carbon nanotube masterbatch, and the ratio of the graphene or carbon nanotube to the resin is 1:20 'where the resin may be non-polar High-density polyethylene (HDPE); Step c, complete the PPTC thermistor composition by adding black in the mixed graphene or nano tube and the resin, wherein the carbon specific weight percentage is a composition 5 0 to 60%, and the weight percentage of the graphite is less than or equal to 10% of the composition. Another method is to provide a graphene or carbon nanotube in powder form in step a, and then directly mix with the resin and carbon black to complete the pPTC thermistor composition. The PPTC thermistor composition is compounded at 201120922 (compouriding) at a suitable temperature, and then extruded through a twin-screw extruder to form a continuous sheet, using upper and lower metal foil sheets (generally nickel plates, The nickel-plated copper plate or the nickel-copper alloy is heated and laminated to form a sheet-like composition of the sandwich, and the PPTC thermistor element having the upper and lower electrodes of the metal foil plate is formed by various post-processing techniques. The ppTC thermistor element can be fabricated as a single-layer PPTC thermistor element or as a two- or multi-layer stack package similar to a printed circuit board to achieve multilayer PPTC thermistor. It is worth mentioning that the present invention has the following advantages over the conventional thermistor system: 1. The conductive property of the graphene or carbon nanotube is greatly improved, and the resistivity of the overall PPTC thermistor is greatly reduced. Under the same resistance length (l) and cross-sectional area (A) conditions (R=pl/A), when the resistivity (p) decreases, the resistance (R) also decreases, which can improve the current carrying capacity of the PPTC thermistor. rate. 2. As the volume resistance of carbon black decreases, the amount of carbon black added (1〇ading) can be reduced by 'inquiring time' to increase the fluidity of the existing composition formulation, and the dispersion of carbon black in the resin, and uniformity, And reduce product defect rate. 3. The number of surface functional groups of graphene or carbon nanotubes can be controlled according to the polarity of the resin to adjust the compatibility with different resins. 4, by a simple tempering step can produce conductive grade graphite thin or rice carbon are combined with this tempering step, the conductivity level, graphite crucible or carbon tube compared to the crucible: reduction method (cheimcaUy Reduced) The conductive grade graphite is made of thinner and has a conductivity of 10 times. It is possible to simultaneously increase the cross-sectional area of the electronic component to simultaneously reduce the resistance of the electronic component to increase the current carrying capacity of the electronic component. 201120922 6. There is no need to change the existing product design, existing process, and subsequent processing, and compatible with the existing process. The technical contents and technical features of the present invention have been disclosed as above, and those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention is not limited by the scope of the invention, and the invention is intended to cover various alternatives and modifications. [Simple description of the diagram] The first figure is a schematic diagram of the structure of a general overcurrent protection device. [Main component symbol description] Overcurrent protection device 10 Current sensing layer 11 Internal electrode layer 12 Current sensing element 13 Insulation layer 14 Solder resist layer 15 External electrode layer 16