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1.Platinum resistance introduction 2.The reference for types 3.Product picture

Platinum resistance introduction I. integrative sinter outward type platinum-ceramic resistance       This product is a new type platinum resistance. As the wire-wound platinum resistance has the characters of better anti overload ability, low spontaneous heating, conforming the metrology requirement etc., our factory director, Mr. Yang Zhonglin, combining the characters of platinum-chip resistance like small volume, antivibration, quick response and so on, carried out a integrity design, many times testing and put it into production.    The character of integrative sinter outward type platinum-ceramic resistance (patent number: ZL02210746-0)    In the structure of this platinum resistance (refer to the figure), the leads is sintered together with resistance at opposite side, and drill though the resistance, no tensile stress on the leads and pottery at the position of sinter, therefore, the lead is ruggedization, and the sinter is not easy to break under force; another advantage is that the platinum wire is sintered on the surface of the resistance and covered by pottery which makes them together and the response speed of components is fast; as the platinum wire is on the surface of the resistance, the effective area of dissipation is big, the cover is thin, the thermolysis is fast, therefore, the spontaneous heating coefficient is low; as the platinum wire is closed in the rigid body of pottery, its antivibration ability, stability and life are all good; as the sintering temperature is high (class -200℃-500℃will be sintered under 800℃, class -200℃-700℃ will be sintered under 900℃) the expansion coefficient of platinum wire is higher than pottery, under the sintering temperature, the platinum wire get the max. volume, as the temperature goes down, the pottery is solidified and form a shell around the platinum wire, from microcosmic view in the application temperature range, one wire has one hole, and the all the wires are at the condition of no tensile stress. If there is a strong current, the wire still stay in the shell after volumetric expansion for heating, the shell can not be broken and the inherence parameter of the component will not be changed. That’s why this type of platinum resistance can be use by hot-wire type flow sensor. (refer to hot-wire type flow sensor) 1. Compare with inner wire platinum-ceramic resistance, the aspects of anti overload ability, antivibration ability, response speed, stability have obvious advantages, and the spontaneous heating coefficient are similar. 2. Compare with platinum-chip resistance, it has the characters of super anti overload ability, low spontaneous heating, and the stability and linearity is better than platinum-chip resistance, the antivibration ability is similar, but the volume is bigger than platinum-chip resistance, the response speed is slower. Under the condition needs rapid response the components of min. Φ0.55mm can also meets the requirement, such as hot-wire type air flow meter anemometer etc. 3. it is safe in the indicated range ability, no false reported range ability, which makes it develop a school of its own in temperature range of 300℃～700℃. 4. the voluntary standards is “Industry Standard of the People's Republic of China” JB/T 8622-1997, this standard confirm with the resistance-temperature relationship formula and graduation form of IEC751:1983.

Platinum resistance Knot the composition

Specification table of resistance core 　 Graduation No. Size(mm) Application temperature range for use Precision Inspection current Material of lead Purpose B A Super A Pt100 φ2.2×10 -200℃ ～500℃ V V   0～3mA φ0.4 Silver wire For industrial use mostly Pt100 φ1.8×6 -200℃ ～500℃ V V   0～3mA φ0.4 Silver wire For industrial use mostly Pt100 φ1.8×8 -200℃ ～500℃ V V   0～3mA φ0.4 Silver wire For industrial use mostly Pt100 φ1.6×8 -200℃ ～500℃ -200℃ ～800℃ V V   0～3mA φ0.2 platinum wire Used for industrial armoured resistance mostly Pt100 φ3.2×20 -200℃ ～800℃ V V V 0～10mA φ0.4 platinum wire Used for high stability metrology products Pt1000 2×10×1 -50℃ ～300℃   A   0～1mA   Made in German and for industrial use mostly Pt20 φ1.6×12 ≤200℃         φ0.20 platinum wire Used for gas flow sensor and assay and analysis apparatus Pt20 φ2.4×22 ≤200℃         φ0.4 platinum wire Used for gas flow sensor Pt20 φ2.8×22 ≤200℃         φ0.4 platinum wire Used for gas flow sensor Pt20 φ3.1×22 ≤500℃         φ0.4 platinum wire Used for high temperature gas flow sensor Pt20 φ3.1×22           φ0.15 Silver platinum alloy Used for automobile air-flow meter, anemometer teaching appliances etc.The recommence speed is about 10ms      II. Platinum-isinglass resistance, platinum-glass resistance and platinum-ceramic resistance     1. The platinum-isinglass resistance and platinum-glass resistance are all outward type, they have advantages of simple technics and low production cost as well as the disadvantages of not antivibration and easy to become failure under high temperature. The main reason for the failure is the thermal expansion coefficient of the framework is far less than that of platinum wire, under high temperature, the clearance between the framework and platinum is too big, say, looseness, together with the external vibration, the framework is lose the restriction for platinum wire, therefore, the turn to turn short circuit is caused; furthermore, after long time vibration, even in the low temperature, the platinum wire also can be worn and torn by framework and the increasing of numerical value of resistance or turn off will be caused. There is a blank wall for this structure, that is, as the temperature change, the platinum will be elongated or shortened, as time passes, the numerical value of resistance will be increased obviously.     2. Platinum-ceramic resistance, it has advantages of simple technics and good out looking as well as the disadvantage of can not be competent for the vibration conditions under fairly low temperature (ex. -200℃). In its structure, the platinum wire is made into spring form, and drill through the fine porcelain tube with 2 holes or 4 holes, the platinum wires of different holes are in series connection and leaded out by leads at one side. The reasons for not antivibration are: its internal winding just like hanging electric stove wire, under high temperature, it just like the electric stove wire is electrified, after electric stove wire electrified, the wore becomes weak, as the time passes, the turn to turn distance of upper wires will be increased, and the turn to turn distance of will be shortened, this kind of effect will be more obvious as the stronger of the current and the higher of the temperature, and under this condition, if there is any vibration, the turn to turn short circuit will be caused. The reason why the antivibration ability of platinum-ceramic resistance is inversely proportional to temperature is just like this. In order to solve this problem, the pottery granules are filled into the holes to restrict the platinum wire, but as the matter of fact, after the edges and corners of the pottery granules are worn off, the above problems will be happened again. Therefore, in order carry out measure under high temperature with vibration, Pt100 or Pt10 made by platinum wire with thicker diameter were adopt, and they worked, but as the diameter is thicker than before, whatever under high temperature or low temperature, their rigidity are increased. Although this way woks but couldn’t solve the problem radically. Further more, there is a problem for platinum-ceramic resistance, that is the winding is always grind with framework whatever under high temperature and low temperature, as the time passes, the numerical value will be increased or the turnoff will be caused. III. Platinum-chip resistance      Platinum-chip resistance overcomes the disadvantagels of above three platinum resistance completely, but as the amount of metal is too less (the thickness of common chip is 3μM, the thickness of thick chip is 7μM), its anti overload ability is not good enough, during jointing, the current pass through the resistance body and form loop in error, and the original precision will be changed. Furthermore, as the wires of 100Ω are collected on a ceramic wafer of 3.2×1.6mm too much, and only single side heated, which made its spontaneous heating coefficient increase, so its inspection current must be under 0.5mA, however, the inspection current provided for primary element of secondary instrument used and produced by our country is 1~5mA (3mA commonly), therefore, the temperature will beyond the criteria for the inspection current of primary element is too strong. Otherwise, the corrugation distortion is easy to be formed on platinum-chip resistance which can change the numerical value, the thermal expansion coefficient of platinum is much bigger than that of ceramic wafer, after long time to-and-fro the resistance is worn out and the corrugation distortion will be formed, under this circumstance, the chip is not connected with ceramic wafer completely, the length and numerical value are all increased. That is the main reason when the platinum-chip resistance woks under 300℃ the turnoff is easy to be happened and the numerical value is not stable. Most of people think it is suitable for the class of ≤100℃B     The spontaneous heating phenomena of platinum-chip resistance is always ignored by people. For example, if it is used in multi-path polling system, people will find the numerical value of every path will be always increased gradually, some people thinks that is for the bad quality of the meter or temperature of the system is not stable, but as the matter of fact it is not so, the reason is: before display, temperature of platinum resistance for the displaying path is same with the inspection environmental temperature, and there is no inspection current for this component, but when the path is displayed, the inspection current will be connected to the platinum resistance of the displaying path by analog switch, the thermal effect of Q＝0.24I2Rt will be produced (that is spontaneous heating). As the volume of chip component is small, so its heating effect is obvious, the numerical value increase process of meter is the temperature increase process of chip component. The requirement for the precision of the inspection current of components with big spontaneous heating coefficient is restricted, so it is not suitable for the high precision measure. Wire-wound platinum resistance is better for it has bigger volume and area of dissipation, its thermal capacity is bigger as well, the chose of the component is just according your concrete requirement, it depends on which aspect you need.      Generally, in the same apparatus (the inspection current is 2-3mmA commonly), under the same temperature, and the temperature is measured by wire-wound platinum resistance and platinum-chip resistance simultaneously, the result from platinum-chip resistance is 1-2℃ higher than that of the wire-wound platinum resistance. Linkman: Yang Zhonglin tel：0416-2327769,0416-2390220，13009333651　fax：0416-2362201