In electronic circuit design, choosing resistors can sometimes be quite confusing, especially for critical positions such as current detection and sampling. Many people may ask: Are alloy resistors necessarily better than thick film resistors? Today we will talk about this topic.
Simply put, alloy resistors are indeed superior to thick film resistors in many key performance aspects, but they may not be suitable for all scenarios. Which one to choose depends on your specific needs.
What are the core differences?
Although both are called resistors, their 'inside' is completely different.
Alloy resistors, as the name suggests, use alloys such as manganese copper and constantan as their core materials. You can imagine it as a 'solid alloy' with a solid structure. This material determines its characteristics: the resistance is usually very low (milliohm level), it can withstand high currents, and the temperature drift is small. For example, the MI series alloy resistors launched by Fenghua High Tech can achieve a minimum resistance of 0.5m Ω, and their thickness and volume are reduced by half compared to traditional products, making them very suitable for today's compact circuit designs.
Thick film resistors, the process is more like "printing". It is made by printing a layer of metal oxide slurry (such as ruthenium based) on a ceramic substrate and then sintering it. This process has low cost, high efficiency, and a particularly wide range of resistance values. Like the AS series thick film resistors newly released by Fenghua High Tech, the temperature drift can be controlled within ± 25ppm/℃ with an accuracy of ± 0.1%, which is already a quite high level.
Practical scenario competition
To give you a more intuitive understanding, let's take a look at a few real-life scenarios:
High current sampling: the absolute domain of alloy resistors
For example, in areas such as lithium battery protection boards, motor drives, and fast charging, the current can easily reach 10A, 20A, or even hundreds of amperes. At this point, thick film resistors are usually not very effective.
Surge resistance: The surge current during the initial startup of the device is very high. Alloy resistors, because they are alloy blocks, can easily withstand them. However, the internal structure of thick film resistors is uneven, and sudden high currents can easily cause local overheating and direct burning.
Low temperature drift: When the current is high, the resistor itself heats up severely. The temperature drift of alloy resistors can reach 50ppm/℃ or even lower, and the resistance value changes very little with temperature, so the measured current is accurate. The temperature drift of ordinary thick film resistors is often above 100ppm/℃, and the error will be much larger.
High precision sampling: alloy resistors outperform
In applications such as BMS battery management systems and servo control that require precise control, sampling accuracy directly affects the control effect. The accuracy of alloy resistors can easily achieve ± 1% or even ± 0.5%, coupled with low-temperature drift characteristics, they can maintain high accuracy throughout the entire operating temperature range. Although thick film resistors can achieve high precision, they are limited by temperature drift and long-term stability, and may be inferior in harsh environments.
High voltage and universal scenarios: Thick film resistors also have advantages
This is not to say that thick film resistors are useless. The advantages of thick film resistors are reflected in high-voltage division and general signal circuits.
High voltage resistance: In the 800V high-voltage platform or photovoltaic system of new energy vehicles, it is necessary to monitor voltages up to several hundred or even thousands of volts. At this point, multiple high-voltage thick film resistors need to be connected in series for voltage division detection. Thick film resistors perform well in high voltage resistance and sulfur resistance.
Cost effectiveness: If the requirements for sampling accuracy are not high, or if it is only used for ordinary current limiting and voltage division, then cheap and universal thick film resistors are of course the most economical choice.
Summarize
Pursuing ultimate performance, choose alloy resistors: If your project requires detecting high currents (over tens of amperes), high precision, and large current surges in the circuit environment, don't hesitate to directly install alloy resistors. It is the preferred high-performance solution.
Pay attention to cost-effectiveness and choose thick film resistors: If you are sensitive to cost in the fields of consumer electronics, general power supplies, etc., and the current is not large (within a few amperes), or require high voltage sampling, then mature thick film resistors can fully meet your needs.
Where can I find these resistors?
It is important to find a reliable channel for both high-performance alloy resistors and mature and reliable thick film resistors.
You can look for Shenzhen Shunhai Technology Co., Ltd. They represent a wide range of brands and categories, and can provide products such as alloy resistors and fuses.
In addition, you can also browse vertical e-commerce platforms such as Huanian Mall, directly screen parameters, compare prices and take samples online, which will greatly improve the efficiency of finding goods.
