MF72功率型NTC热敏电阻器
产品简介
MF72功率型NTC热敏电阻器是以过渡金属氧化物为主要原料制成的半导体陶瓷元件。
属于负温度系数热敏电阻器的范畴。
为了避免电子电路中在开机的瞬间产生的浪涌电流，在电源电路中串接一个功率型NTC热敏电阻器，能有效地抑制开机时的浪涌电流，并且在完成抑制浪涌电流作用以后，由于通过其电流的持续作用，功率型NTC热敏电阻器的电阻值将下降到非常小的程度，它消耗的功率可以忽略不计，电压几乎均加到后面设备从而保证线路的正常工作，所以，在电源回路中使用功率型NTC热敏电阻器，是抑制开机浪涌保护电子设备免遭破坏的最为简便而有效的措施。
应用范围
适用于转换电源、开关电源、UPS电源、各类电加热器、电子镇流器、各种电子装置电源电路的保护以及各类显像管、显示器、白炽灯及其它照明灯具的灯丝保护。
特点
1.体积小，功率大，抑制浪涌电流能力强。
2.反应速度快。
3.材料常数（B值）大，残余电阻小。
4.寿命长，可靠性高。
5.系列全，工作范围宽。
传感器SENSORSSENSOR MANUALTEMPERATUREMEASUREMENTCONTROLSHANGHAI BENMU INDUSTRY CO., LTD.上海本牧实业有限公司QUICK LINKSCONNECTINGSENSOR TECH电阻值耗散常数ResistanceThermal dissipation constantB值热时间常数B constantThermal time constant热敏电阻的电阻值R和绝对温度T之间，有以下近似关系。
Between resistance R and absolute temperature T, there is the following approximate relationship.11T1T2根据公式、可以求证任意温度T时的热敏电阻R。
Thermistor resistance R at any temperature T can be calculated from equation (1)R1: Resistance (Ω) at absolute temperature T1 (K)绝对温度T1 (K) 时的电阻值R2: Resistance (Ω) at absolute temperature T2 (K)绝对温度T2 (K) 时的电阻值A thermistor is "a thermally sensitive resistor"that is a semiconductor whose resistance varies significantly with temperature.In general,there are two types thermal senstive resistor.One is PTC (Postive Temperature Coefficient);the resistance increases as temperature increases.The other is NTC (Negative Temperature Coefficient);the resistance decreases as temperature increases.The following description is applicable only to NTC thermistors.热敏电阻是应用于信息系统与控制系统的敏感元件，主要用于对温度的测量、控制、保护及用作加热器。
Important Information on the Use ofNTCLE Leaded NTC ThermistorsMOUNTING INSTRUCTIONS1. SOLDERINGLeaded thermistors comply with the solderability requirements outlined in IEC 60068-2-20. To prevent damage when soldering leaded NTC thermistors, care must be taken to prevent excessive heat from being conducted through the leadwires or directly to the thermistor body. The maximum process temperatures, the maximum time of exposure, and the minimum distances that need to be respected also depend on the material used for the leadwires. For dip, wave, and iron soldering of RoHS-compliant NTC thermistors, the combined solder conditions listed below should be followed:The use of resin-type flux or non-activated flux is recommended. Failure to follow the above soldering conditions may result in thermal-electrical damage to material and permanent resistance changes. NTCLE thermistors are not designed for reflow soldering processes. If a heat shrink tube is applied to an NTCLE thermistor, the heating temperature of the shrink tube must not exceed the mentioned reflow soldering temperatures and times. Use of the coating outlets as product stops should be avoided, as lacquer may enter the PCB holes and prevent solder flow and the minimum distance required between the solder joint and thermistor body cannot be reached. Excessive heating can cause the internal solder junction to melt.2. COLD JOINING AND WIRE BENDINGCold joining techniques such as crimp splicing can be applied to NTCLE thermistors for connector applications and making cable wire extensions. When crimp splicing, care should be taken to avoid causing intermittent contacts. The robustness of the termination leads meet the requirements of IEC 60068-2-21. During bending or separating of the leads, there should be no mechanical stress at the outlet of the coated sensor, and the leads may not be bent closer than 4 mm from the outlet of the coated body. The bending radius should be at least 3 x the wire diameter or a minimum of 5 x the insulated wire diameter. The part should not be exposed to mechanical stresses, including tensile, torsion or vibration forces, during normal operation in the application. For shrink tube fixation of the thermistor body and wires, see the “Soldering” section (1) of this document.3. STORAGE - SHELF LIFENTCLE thermistors need to be stored in their original packing containers. The storage location and package containers need to be maintained within following limits:Thermistors must not be stored in corrosive or deoxidizing atmospheres (Cl 2, H 2S, NH 3, NO x , SO x , etc.). Avoid storage in heat or direct (UV) sunlight. The presence of ozone or ionizing radiation must be avoided all times. H umidity, temperature, and container materials are critical factors that can influence the solderability of the parts. Touching the exposed metal leadwires may change their soldering properties.Shelf life: properly packaged and stored NTCLE thermistors have a minimum shelf life of 24 months after their manufacturing date (DC). Thermo-electrical functionality will not be influenced after longer storage time under the conditions described above. The solderability of exposed leads should be checked before using parts that have been stored for more than 24 months storage after their manufacturing date.LEADED NTC THERMISTORS: NTCLEWITH Cu WIRESØ < 0.65 mmWITH Ni OR STEEL WIRES Ø < 0.55 mm Wave or Dip SolderingMaximum bath or wave temperature260 °C 260 °C Maximum soldering time3 s 5 s Minimum distance from thermistor body6 mm 3 mm Solder Iron (Manual or Robot)Maximum solder tip temperature340 °C 340 °C Maximum soldering iron wattage30 W 30 W Maximum soldering time2 s3 s Minimum distance from thermistor body6 mm 3 mm PiP / PiH Reflow SolderingNot recommended Not recommended Maximum thermistor body temperature T pToper. Maximum +15 °C Toper. Maximum +25 °C Maximum exposure time to T p max.30 s 30 sStorage temperature:10 °C to 40 °CRelative humidity (without condensation):10 % to 70 %4. HANDLINGNTCLE thermistors must not be dropped. When handling the devices, chip-offs or any other damage must be avoided. Do not touch components with bare hands; gloves are recommended to prevent contamination of thermistor surface during handling. Rough handling of NTCLE thermistors may result in coating adhesion failures or coating cracks. For non-insulated NTCLE thermistors, please refer to the “Visual” paragraph of “Inspection Measuring” section (7) of this document.5. SEALING AND POTTINGNTCLE thermistors may only be sealed, potted, or overmolded in suitable resins if it is clearly mentioned and allowed in their respective datasheets. The following series cannot be potted: the NTCLE100 standard precision, and NTCLE101 and NTCLE203 accuracy lines. Sealing or potting can affect the reliability of the component. The potting material must be compatible with the use of electronic components, electrically non-conductive, and chemically stable across the whole operating temperature range. Potting or overmolding in polyamide-based resins is not recommended. When sealing, potting, or overmolding is permitted according to the datasheet, there must be no mechanical stress exerted on the component due to thermal expansion or compression during the production process (curing / overmolding) or in the final application. There must be no residual forces or stress on the device during normal operation. The upper category operating temperature of the thermistor must not be exceeded. Ensure that the materials used are chemically neutral and stable at the maximum operating temperature. If using a ceramic adhesive / potting or filling material, avoid phosphate-based binders. As thermistors are temperature-sensitive components, molding and sealing will affect the thermal surrounding and will influence the response time, power dissipation, and thermal gradient. Extensive testing is encouraged in order to determine whether overmolding or potting influences the functionality and / or reliability of the component.6. CLEANINGCleaning processes can affect the reliability of the component. If cleaning is necessary, mild cleaning agents are recommended. Cleaning agents based on water are not allowed. Washing processes may damage the product due to the possible static or cyclic mechanical loads (e.g. ultrasonic cleaning). They may cause cracks, which might lead to reduced reliability and / or lifetime. Intensive spraying may lead to coating damage.7. INSPECTION MEASURINGResistance Versus TemperatureNTC thermistors exhibit a large resistance change depending on the changing surrounding temperature. The change of resistance can be as high as -8 % per degree Celsius. When measuring or inspecting resistance values of precision NTC thermistors, it is advisable to immerse the thermistor body and its connecting leads in a good thermal conductive homogeneous medium. Such a medium is preferably silicone oil or PFPEs non-reactive, per-fluorinated liquid polymers. Water is not recommended, because of its electrical conductivity. In any case, the measured parts should be cleaned and dried before further use or be discarded. The liquid medium should be measured with a calibrated thermometer and referenced close to the NTC thermistor body. Measuring NTC thermistors in air can and will be influenced by many parameters, including radiated heat and cold / heat flows from surrounding bodies. Measuring currents that can be applied to the NTC thermistor should be low enough to prevent any self-heating or be limited in time. Preferably, electrical power induced by the measuring current should be lower than 10 % of the specified dissipation factor, or generate a temperature increase of less than 0.1 °C. For many NTCLE thermistors, a measuring current of 10 μA to 100 μA will not induce any self-heating. Some ohm meters or DMMs measure resistance values with measuring currents of 1 mA or higher. These currents can heat up some NTCLE thermistors by more than 10 °C.DimensionalAll production batches of NTC thermistors are controlled dimensionally on a statistical basis in order to guarantee compliance with specifications. When designing an NTC in your application, please verify that the application conditions will not induce any compression stress on the coated thermistor body. For example, if the component must be inserted into a tube, the tube’s minimum inner diameter must be larger than the specified maximum thermistor body dimension. Bulk packed NTCLE thermistors have no fixed pitch between the wires and the wires can be in a deviating position.VisualSmall vesicles — sharp edges or micro-cracks on the coated leadwires of liquid epoxy coated, non-insulated NTCLE100, NTCLE101, and NTCLE203 series thermistors — are cosmetic and do not impact the reliability of the parts.8. OPERATIONUse thermistors only within the specified operating temperature range. Never use NTC thermistors in constant voltage mode or outside the specified maximum or derated power. Overpowering a NTC thermistor can cause thermal runaway and fire ignition, short circuits, or open circuit failures. Environmental conditions must not harm the thermistors. Avoid operation of NTCLE thermistors in corrosive or deoxidizing atmospheres (Cl2, H2S, NH3, NO x, SO x, etc.) unless specified. Only use the thermistors under normal atmospheric conditions or within the specified conditions. NTCLE thermistors may not be used in vacuums, or at very low or high air pressure. Avoid any contact with water or electrically conductive liquids, unless specified in their respective datasheets. It must be ensured that no water enters the NTC thermistors (e.g. through terminals). For measurement purposes, see the “Inspection Measuring” section (7). Avoid dew formation and condensation unless the thermistor is specified for these conditions. During operation, any bending, twisting or movement of the cables or wires should be prevented.NTCLE thermistors are non-insulated unless a minimum insulation dielectric withstanding voltage is clearly specified in the datasheet. For non-insulated thermistors, any contact with a metallic or conductive surface could result in a leakage current, disruption, short circuit, or a malfunctioning of the component. Insulated thermistors should not be used above their specified dielectric withstanding voltages. The following series are non-insulated and not recommended for applications in which they are exposed to thermal shocks: NTCLE100 standard precision, and NTCLE101 and NTCLE203 accuracy lines.9. FAILURE MODESFor safety critical applications, be sure to provide an appropriate fail-safe or redundancy function in the circuit to prevent secondary (product) damage caused by a malfunctioning or failed NTC thermistor. For every use of Vishay thermistors, it is the customer’s responsibility to consult and respect the Vishay disclaimer notice, which is part of every Vishay product datasheet. If you have any doubt as to the possible failure modes in your application, consult Vishay.This list of guidelines and information does not claim to be complete, but represents the experiences of Vishay and may be supplemented, adapted, or enhanced at any time.。
NTC Thermistors - Disc and Chip StyleTemperature Measurement and Control Thermistors DISC and CHIP StyleDISC & CHIP NTCSTYLE NTC THERMISTORFeatures•Wide Ohmic Value Range•Accurate & Stable•Fast ThermalResponse Time•Tight Tolerances•High SensitivityNTC ThermistorsNegative Temperature Coefficient (NTC) thermistors are thermally sensitive semiconductor resistors which exhibit a decrease in resistance as absolute temperature increases. Change in the resistance of NTC thermistor can be brought about either by a change in the ambient temperature or internally by self-heating resulting from current flowing through the device. Most of the practical applications of NTC thermistors are based on these material characteristics.NTC Disc and Chip Style DevicesAmetherm manufactures Disc and Chip style thermistors in resistance values ranging from 1.0 ohm to 500,000 ohms. These devices are suitable for a range of resistance values and temperature coefficients from relatively low resistance and temperature coefficients to very high values. Precision resistance tolerances are available to 1%. Standard resistance tolerances are from 5% to 20%. All tolerances are specified at 25°C or may be specified at any temperature within the operating temperature range of the thermistor.Thermistor Terminology for Temperature Measurement & Control Devices•The dissipation constant (D.C.) is the ratio, normally expressed in milliwatts per degree C (mw/°C), at a specified ambient temperature, of a change in powerdissipated in a thermistor to the resultant change in body temperature.•The thermal time constant (T.C.) is the time required for a thermistor to change63.2% of the total difference between its initial and final body temperature whensubjected to a step function change in temperature under zero-power conditions and is normally expressed in seconds (S).•Alpha () or Temperature Coefficient or Resistance is the temperature coefficient of resistance is the ratio at a specified temperature, T, of the rate of change of zero-power resistance with temperature to the zero-power resistance of the thermistor.The temperature coefficient is commonly expressed in percent per degree C (%/°C).NTC DISC & CHIPSelectionConsiderations•Select Req'd. Resistance Value & Temperature Coefficient•Determine Accuracy Req'd.•Review Power Dissipation•Determine Operating Temperature Range•Review Thermal Time ConstantThermistor ApplicationsTime and temperature are two of the most frequently measured variables. There are numerous ways of the measuring temperature electronically, most commonly by thermocouples and negative temperature coefficient (NTC) thermistors. For general purpose temperature measurement, NTC temperature sensors can operate over a wide temperature range (-55 to +300°C). They are stable throughout a long lifetime, and are small and comparatively inexpensive. Typically, they have negative temperature coefficients between -3.3 and -4.9%/°C at 25°C. This is more than ten (10) times the sensitivity of a platinum resistance thermometer of the same nominal resistance. Ametherm's Disc & Chip style thermistors are used in many applications that require a high degree of accuracy and reliability.Some of the most popular applications of NTC thermistors include: •Temperature Compensation•Temperature Measurement & Control•Fan Motor Control•Fluid Level & Temperature SensorsNTC DISC & CHIP - Selection Process•Select R Value•Determine R @ T•Calculate DEV for R @ T•Evaluate Power Rating (D.C.)•Review T.C. RequirementsSelection considerations for NTC Disc and Chip DevicesPower dissipation is a common problem in the use of thermistors as they can only dissipate a certain amount of power.•If the power dissipated exceeds the dissipation constant (D.C.) rating of the sensor it is likely that it will exhibit self heating.1DA131J 130 A 0.1 0.06 3 10 28 0.07 1DA131K 130 A 0.1 0.06 3 10 28 0.07 1DA500J 50 A 0.1 0.03 3 6 28 0.07 1DA500K 50 A 0.1 0.03 3 6 28 0.07 1DB102J 1,000 B 0.1 0.06 3 10 28 0.07 1DB102K 1,000 B 0.1 0.06 3 10 28 0.07 1DB102K-EC 1,000 B 0.1 0.06 3 10 28 0.07 1DB501K 500 B 0.1 0.03 3 6 28 0.07 1DC103J 10,000 C 0.1 0.03 3 6 28 0.07 1DC103J-EC 10,000 C 0.1 0.08 4 12 28 0.07 1DC302J 3,000 C 0.1 0.08 4 12 28 0.07 1DC502J 5,000 C 0.1 0.08 4 12 28 0.07 1DC502J-EC 5,000 C 0.1 0.08 4 12 28 0.07 1DE104J 100,000 E 0.1 0.95 3 9 28 0.07 1DE104K 100,000 E 0.1 0.95 3 9 28 0.07 1DE104K-EC 10,000 E 0.1 0.95 3 9 28 0.07 2DA200J 20 A 0.2 0.05 7 20 24 0.1 2DA200K 20 A 0.2 0.05 7 20 24 0.1 2DA503J 50,000 A 0.2 0.05 7 20 24 0.12DB102J 1,000 B 0.2 0.025 7 18 24 0.1 2DB102J-EC 1,000 B 0.2 0.025 7 18 24 0.1 2DB102K 1,000 B 0.2 0.025 7 18 24 0.1 2DB151J 150 B 0.2 0.025 7 18 24 0.1 2DB151K 150 B 0.2 0.035 7 19 24 0.1 2DC102K 1,000 C 0.2 0.035 7 18 24 0.1 2DC302J 3,000 C 0.2 0.1 7 30 24 0.1 2DC302K 3,000 C 0.2 0.1 7 30 24 0.1 2DE103J 1,0000 E 0.2 0.04 7 17 24 0.1 2DE103K 1,0000 E 0.2 0.04 7 17 24 0.1 2DE503K 5,0000 E 0.2 0.04 7 17 24 0.1 3DA100J 10 A 0.3 0.06 8 48 24 0.1 3DA100K 10 A 0.3 0.06 8 48 24 0.1 3DB500J 50 B 0.3 0.025 8 35 24 0.1 3DB500K 50 B 0.3 0.025 8 35 24 0.1 3DE502J 5,000 E 0.3 0.025 8 35 24 0.1 3DE502K 5,000 E 0.3 0.025 8 35 24 0.1© 1998 -2013 Ametherm, Inc。
