Why Choose Tiangeng
Professional Production
We are a company specializing in the design, development, and production of precision series resistors, precision sampling resistors, precision shunts, precision resistor dividers, non-inductive resistors, and power resistor.
Strict Management System
We implement a high-tech enterprise quality management system and strictly follow ISO9001 service management standards and work processes. We will establish detailed product files for customers, respond to customer service requests on time, and assist customers in solving problems.
Advanced Equipment
We have advanced production equipment, such as precision photolithography machines, high and low temperature testing equipment, Agilent 3458A and other precision instruments, digital high-resistance calibrators, high-temperature sintering equipment, heat treatment equipment, etc.
Wide Application
The products produced are widely used in sensors, scales, rail transit, ships, new energy, precision automation control, power instruments, medical equipment, power automation control, precision instruments, measuring instruments, automobiles, electromechanical railways, communications and other fields.
What is Precision Foil Resistance?
Precision resistors built on unique Bulk Metal® Foil technology provide very low temperature coefficient of resistance (TCR) and exceptional long-term stability even in extreme temperatures. The devices provide a wide range of resistance values, with any resistance value within their given range available at any tolerance with no additional cost or lead time effect. On top of this specific “as required” values can be supplied at no extra cost or delivery.
Wiring a resistor in a circuit will reduce the current by a precise amount. If you look at resistors from the outside, they most likely look the same. However, if you break it open, you'll see an insulating ceramic rod running through the middle with copper wire wrapped around the outside. Resistance depends on those copper turns. The thinner the copper, the higher the resistance since it's harder for the electrons to pass through it. As we've found out, it's easier for the electrons to flow in some conductor materials than insulators.
George Ohm studied the relationship between resistance and the size of the material that was used to make the resistor. He proved that the resistance (R) of a material increases as its length increases. This means that the longer and thinner wires offer more resistance. On the other hand, resistance decreases as the thickness of wires increases.
Note: Conductors have much lower resistivity than insulators. At room temperature, aluminum comes in at about 2.8 x 10-8 -Ωm, while copper is significantly lower at 1.7 x 10-8 Ω-m. Silicon has a resistivity of about 1000 Ωm and glass measures about 1012 Ω-m. Resistivity varies for different materials.
Characteristics of Precision Foil Resistance
Foil resistors achieve a low TCR by taking advantage of two characteristics of the foil. The resistance of the foil naturally increases as temperature increases. The resistor is manufactured so that rising temperature causes compression of the foil. This makes the resistance drop as temperature rises. The total effect is one of very little resistance change as temperature changes.
PCR is a measure of how resistance changes as the resistor heats up due to current flow through it. Foil resistors have a very low PCR value.
Thermal stabilization refers to the speed at which resistor reacts to changes in current flow and ambient temperature. The same composition and manufacturing characteristics that give foil resistors their low TCR also provide quick thermal stabilization. These resistors can have stabilization times of less than a second, as opposed to standard resistors, which may have times measured in minutes.
This parameter tells how close to the nominal value of resistance an actual resistor will be. For example, a company may sell resistors that are advertised to be 100 ohms with a tolerance of 1 percent. This means that the actual value of one of these resistors may range from 99 ohms to 101 ohms. Foil resistors can be made to have tolerances as low as 0.001 percent.
In many circuit applications, noise generated within the circuit is to be avoided as much as possible. Audio systems are a prime example of this. The crystaline properties of the metal alloy in a foil resistor combined with special manufacturing techniques allow current to flow through these resistors with low noise generation.
Some resistors, particularly those of carbon composition, will display changing resistance in response to changing voltage. Foil resistors are constructed so that this effect is virtually non-existent.
Reasons to Use Precision Foil Resistors
01.Accuracy
02.Stability
03.Low Temperature Coefficient
04.Low Noise
05.Low Inductance and Capacitance
06.High Power Handling Capability
Difference Between Precision Resistors and Ordinary Resistors
Difference in Material Performance
Within a certain temperature range, the tolerance of precision resistors is much smaller than that of ordinary resistors.
Substantial Difference
The temperature stability of the materials used to make precision resistors is higher than that of ordinary resistors. For example, the temperature tolerance of ordinary resistors is 1% - 5%, while the tolerance of precision resistors is only 0.1% or less.
Difference in Cost
Because precision resistors use materials with higher temperature stability, they are much more expensive than ordinary resistors.
Difference in Digital Models
Ordinary resistors are labeled with 3 digits, the first two are valid numbers, the latter is the power. For example: 152 means 15 * 102= 1500 ohm. Precision resistors are labeled with 4 digits, the first three are significant figures, the latter is the power, for example, 1502 means 150 *102 = 15000 ohm.
Difference in Color Wheel Reading
The color wheel reading of ordinary resistors and precision resistors are almost the same. The first two digits of ordinary resistors are numbers. For precision resistors, the first three digits are numbers, the fourth ring is multiplying power and the fifth wheel is the tolerance, so the precision resistor is also called the five-color ring resistor.
Difference in Application
Compared to ordinary resistors, precision resistors are more costly, so they are mainly used in high-precision circuits of signal conversion, bridge circuits, sampling circuits, precision voltage division circuits, and so on.
Applications of Precision Foil Resistance
4mA to 20mA Current Loops
Entire production batches have been lost or suffered reduced reliability when critical parameters were not kept within narrow limits. The precision resistor used in the analog sensor has a major impact on the performance and reliability of monitoring and control circuits. The resistor's long-term stability, robustness against ESD, and resistance to moisture are all factors that need to be taken into consideration. Foil precision resistors are the devices of choice to meet these requirements.
Bridge Networks
This application calls for four resistors in total; three need to be built on the most stable technology available, while the fourth works as a bridge completion sensor detecting the output from the function being measured. The resistors are matched as closely as possible and mounted in such a way that they can be kept at a common temperature in service. This function is best served by foil precision resistors, which have a remarkably low temperature coefficient, low thermal EMF, fast response to current change, and/or low power coefficient of resistance.
Current Sensing
A very low-value resistor with a four-terminal connection allows the current to pass through the resistor with minimum power loss and still measure the IR drop to monitor the current. Current sensing of very large amounts of current requires a correspondingly large resistor with a suitable heatsink to draw away the heat generated. Foil resistor technology lends itself uniquely to this application because the flat foil is bonded to a thin ceramic backing, which can dissipate considerable heat to the sink below. The resistors’ very low-temperature coefficient prevents any error drift as a result of self-heating due to high currents.
Differential Amplifiers
The gain of an amplifier needs to be as constant as possible, with minimal influence from the outside world. The feedback and sense resistors used in these applications have different heat dissipation and self-heating characteristics. In a differential amplifier, we are balancing not just two resistors but four or more; and this means all these devices need to exhibit near-identical behavior over a wide range of values. Foil resistors satisfy these requirements better than any other resistive technology.
Gyro Navigation Controls
Electrostatic gyros use electronic controls to realign the gyro during orientation changes. Other gyro technologies have equally critical dependence upon precision resistors. The electronics are most often in the form of resistor networks defining the various functions of “on-off detector,” “azimuth control,” and so forth. These functions are critical to the transfer of information, for which airborne and outer space missions typically provide only one opportunity for success. This is just one reason that the unequaled precision and stability of foil resistors is a must for gyro navigation applications.
Lithium Ion Battery Chargers
Li-ion battery chargers are complex and challenging circuits. They require accurate current and voltage settings and monitoring, as well as a constant current and voltage. If these accuracy requirements are not met, the charger will fail to completely charge the battery and reduce battery life, or otherwise permanently reduce battery performance. Selection of the proper current sense resistors can help prevent this from happening, in airplanes and elsewhere. Foil resistors deliver the high accuracy required.
General Tips for Selecting the Right Resistor
Select the resistance
The electrical property of a resistor is the resistance. It is the resistance that will oppose or limit current flow. It is identified on a unit ohm (Ω). Current measurement resistors generally have impedance values in the range of several milliohms. To reduce impedance the resistor's solder pads are also often located on the long sides of the component.
Resistor Power Rating selection
The Resistor Power Rating (sometimes called the Resistor Wattage Rating) is defined as the amount of heat that a resistive element can dissipate for an indefinite period of time without degrading its performance. Therefore one should take care to choose a resistor with sufficient power rating, selecting 0.5W when 1W may be needed will result in failure in time.
Select the resistor voltage
Another important classification to consider when choosing the resistance is the voltage value. Datasheets give limits to the maximum working voltage. This is the actual voltage applied over the resistor.
Select the resistor tolerance
There is no perfect resistance, so tolerance must also be taken into account when choosing the resistance. Resistors come from different tolerances such as 10%, 5%, 1%, 0.1% and so on.
Choose the resistor temperature
When selecting the resistor, do not forget the operating temperature range. The temperature coefficient is also stated in the data sheet.
Resistor mounting Style and Physical Size
The mounting style is also a factor in the choice of resistors. You may need surface mounting device or a through hole component. The decision for this is sometimes determined by the application, the power or the availability of the part. Physical size is also an important consideration, especially in products where the space is critical.
Our Factory
Based on many years of producing various precision resistors, our company designs, develops, and produces various resistor cabinets, coaxial resistors, and metal foil standard resistors.
Company Honor
Based on the high-tech enterprise quality management system, we strictly follow ISO9001 service management standards and work processes.
Frequently Asked Questions
We're well-known as one of the leading precision foil resistance manufacturers and suppliers in China. If you're going to buy or wholesale high quality precision foil resistance made in China, welcome to get more information from our factory.
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