Where is the future of shunt resistors?
Published time: 2019-11-29
Resistors are one of the most used components of various electronic products. With the passage of time, electronic products have shown a trend of diversification, which has also led to great changes in resistors. Among them, chip resistors are the most popular in the market, with a market share of 90%, which are mainstream resistance products.
From the technical development trend of chip resistors, according to ROHM's statistics, the most used resistors in the world are still 0402 packaged resistors, which is 1.0 × 0.5mm. This ROHM was in 1989 The first mass-produced resistor is still the most widely used resistor in the world. In addition, resistors such as 0201 and 0603 account for about 85% of total shipments, which is also the current major shipment.
In the field of chip resistors, the larger the package, the higher the power that the chip resistor can handle. But today's market is increasingly demanding ever smaller electronic product sizes, which means the need for smaller components. The continuous reduction in the size of standard electronic devices has resulted in higher power consumption in a smaller PCB space. Therefore, chip resistors must be able to handle higher power per square inch.
At present, the demand for miniaturization is more and more vigorous, and the demand for 0201 and smaller 01005 package resistors has gradually increased year by year. At the same time, the demand for 0603 resistors with larger packages will gradually decrease. It can be seen from the overall market demand that miniaturization is an inevitable technological development trend.
With the demand for miniaturized resistors, a number of new application scenarios have emerged, which also brings new challenges and development opportunities for resistors.
Currently, most of ROHM's resistor sales come from the automotive market. At the same time, with the development trend of the market CASE (ie infotainment, autonomous driving, shared services, electrification), resistors must meet the needs of high-power resistors in the automotive market while meeting miniaturization. Among them, the shunt resistor is widely used in vehicle and industrial equipment for the purpose of detecting current, which also requires the shunt resistor to develop in the direction of small and high power.
In terms of shunt resistors, ROHM has launched a variety of products to meet the needs of different automotive scenarios. In 2006, ROHM released the world's first miniaturized metal plate shunt resistor, and then successively released PSR series of high power (3W, 4W, 5W) low resistance (3 millimeters) from 2014 to 2017. Below Europe). In addition, in 2017, ROHM released the first GMR100 series of GMR series resistors. The biggest advantages of GMR series resistors are good heat dissipation characteristics and low temperature coefficient of resistance. Following GMR100, ROHM also introduced the GMR50 series shunt resistor, the first in the world to achieve 4W power in 5025 size, which meets the needs of the automotive market for resistors.
It is reported that by changing the electrode structure and optimizing component design, the GMR50 resistor can not only save installation space in one step, but also provide stable current detection. In addition, GMR50's resistor body metal uses high-performance alloy materials, which also allows the resistor to provide high-precision current detection and improve reliability.
The device is more space-saving
A small size of 5.0 × 2.5mm, but when the pin temperature Tk = 90 ℃, the industry's advanced rated power of 4W can be used. Compared with the previous products that are also 4W, a smaller size shunt resistor can be used. Device, which can reduce the installation area by 39%.
Stable current detection
Compared with ordinary products, this product has better durability against overcurrent loads. Even if an overcurrent exceeding the rated value flows, the change in resistance value is very small, and stable current detection is possible. According to Wu Bo: "By comparing the overload test of ordinary resistors and GMR50 resistors, it can be seen that when the power is gradually increased, even when the GMR50 resistor is increased to 8 times, its resistance change rate is still 0.5. %, And ordinary products have reached less than 2% at this time. In other words, even under overload conditions, the GMR50 resistor can ensure a small resistance change rate and ensure very stable current detection. " Current detection: In the low resistance range, GMR50 also achieves excellent resistance temperature coefficient.
High-precision current detection
Helps to improve the reliability of the equipment. According to Wu Bo: "In general, the lower the resistance value, the higher the resistance temperature coefficient. The temperature coefficient of resistance reflects the temperature dependence of resistance. The smaller the fluctuation requirements, the more accurate the actual detected value. Especially in In some vehicles or in some harsh environments, the temperature rise inside the car is generally high, but it also has high requirements for reliability. Under this application condition, the lower the temperature coefficient of resistance, the less the resistor affected by the environment. This allows for higher accuracy. "
In addition, the heat dissipation design supported by ROHM is not only for a single resistor, but also for the overall thermal simulation of the entire PCB board, so as to provide corresponding heat dissipation countermeasures. This is also the service that ROHM has been able to provide, and it is also one of the advantages of ROHM resistors. For the future, the development strategy of ROHM resistors is to focus on the growing automotive market, with supply capacity and reliability as its core competitiveness to ensure a stable position worldwide.
Specifically, in terms of shunt resistors, as the rated power of shunt resistors continues to increase, ROHM GMR series resistors will increase the rated power to 10W in the future; PSR series can be upgraded to 15W; PMR and LTR series resistors Will also increase from the current 2W to 3W. In terms of high-reliability resistors, ROHM has two routes: one is to increase the rated power while keeping the package size unchanged; the other is to ensure its anti-surge ability while adapting to miniaturization Unchanged, or the improvement of anti-vulcanization performance, these are the characteristics and advantages of Roma for the automotive market.
At the same time, in order to cope with the increasing demand for resistors in the future automotive market, in June this year, ROHM invested in a new plant in the ROHM factory in the Philippines to expand ROHM's high-power shunt resistors and high reliability. Product lineup and capacity of resistors.
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