Miniaturization leads, use of cooler & stronger material next in rectifiers

Increasing use of ultrasmall but powerful electronic components is encouraging further miniaturization. In rectifiers, the SMD category remains the R&D priority of Chinese manufacturers although DIP variants are still widely available. In particular, companies are highlighting designs with slimmer profiles. One such release from Dongguan Nanjing is 1.5mm in thickness. Despite its superthin structure, the product can handle maximum ratings of 1,000V recurrent peak reverse, 700V rms and 1,000V DC blocking voltages, and 1A average forward rectified, 30A peak forward surge and 50µA DC reverse currents. It withstands operating temperatures as low as -55 C and as high as 150 C. Solderability is based on MIL-STD-202-208 or the US Department of Defense standard.

In addition to miniaturization, Chinese suppliers plan to diversify their base materials to include silicon carbide (SiC), a nontoxic ceramic that can tolerate higher electric fields and will not fail even at elevated voltages. In more exact terms, SiC's breakdown voltage is five to 10 times higher than that of silicon, which is about 600V. This makes SiC components suitable in thermally demanding applications.

Industry analysts are predicting such products will gradually replace not only silicon-based rectifiers but also Schottky and PIN diodes in the future. However, a small group of global leaders, such as STMicroelectronics and Cree, dominate the supply of SiC discrete components.

In China, only a few companies are currently engaged in the development and production of SiC rectifiers. One of them is Beijing-based Global Power Technology, which specializes in SiC power devices. GPT owns a SiC wafer fabrication facility. With greater market uptake and once technology threshold is hurdled, more Chinese manufacturers are expected to venture into this category in the coming years.

Growth drivers

Rectifiers are used in a range of devices that run on DC power, including practically all of today's electronics aspiring for high power efficiency. In addition to DC power supplies, high-voltage power transmission systems and radio signal or detectors, they are needed in mobile phones, laptops, video game systems and TVs. This captive growing market now also includes electric vehicles, smart cities and industrial automation.

In North America, rectifiers are forecast to enjoy a CAGR of 13.4 percent from 2020 to 2026, according to Research and Markets. Globally, the projection by a report published by Report Linker is $6.6 billion by 2026 or 13.6 percent CAGR. The key industry players include ON Semiconductor, Raychem RPG, Spang Power, ABB, STMicroelectronics and Infineon.

Chinese suppliers, who restarted their product expansion in late 2020 after a manufacturing freeze in the first quarter of the year due to the pandemic, are confident of demand growth. Based on interviews by Global Sources Electronic Components, they plan to increase output by five to 10 percent in the coming months.

Yangzhou HY took a step further and invested $14.7 million in a new facility with an area of 46,259sqm. The company moved to the location before the end of 2020. When mass production is reached, it will be able to churn out 25 billion units, of which 15 billion are rectifier diodes, 900 million are bridge rectifiers and 100 million are bypass diodes.

Supply pool

In China, there are more than 400 manufacturers of rectifiers, including those from the US and Japan. Yangzhou Yangjie, Suzhou Good-Ark and WeEn Semiconductor are some of the major homegrown suppliers. Chinese companies export 30 to 80 percent of their output, mainly to Europe, North America and the Asia-Pacific region. They also send shipments to Russia, the Middle East and other parts of Asia.

Over 80 percent of these suppliers are found in the coastal cities of Shenzhen, Dongguan, Zhongshan, Suzhou, Changzhou, Yangzhou, Wuxi, Yueqing and Weihai. There are also factories in Chongqing municipality and Shaanxi capital Xi'an.

The most widely available rectifiers from Chinese manufacturers are Schottky barrier, fast- recovery, bridge and silicon-controlled types, in both DIP and SMD configurations. These generally have low reverse leakage current, can withstand high forward surge current, and ensure low power loss and thermal resistance. Main applications include computers and peripherals, communications equipment, consumer electronics, vehicles and industrial machinery.

Key components used in the production of rectifiers include diodes, chips and thyristors, which may be sourced domestically or from foreign suppliers as required.

The cost of materials and components is expected to remain stable and keep product prices unchanged throughout 2021. However, competition may force some manufacturers to offer slightly lower quotes to attract more orders.

8.6x8.6mm rectifier

This TO-247-8 rectifier from Anhui Qimen Huangshan Electric Appliance Co. Ltd has 20 to 40mA typical current, 100µ leakage current at 25 C and ≤1.5V on-state voltage/gate trigger voltage. It measures 8.6x8.6mm.

The 100-unit minimum order is delivered within seven days.

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Rectifier, supports -50 to 155 C

From Dongguan Lechen Electronics Co. Ltd, this M7(SMA)-13 rectifier has 1,000V maximum repetitive peak reverse and DC blocking voltage, 700V maximum rms voltage, 1.1V maximum instantaneous forward voltage and 1A maximum average forward rectified current. Its operating temperature is -50 to 155 C. The unit meets RoHS 2011/65/EU, WEEE 2002/95/EC and IEC 6124902021 standards.

The minimum order is 3,000 units for delivery within seven days.

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Rectifier with 45A repetitive peak surge current

This WUR6030DCT/WUR6030NCT/WUR6030BCT rectifier from Jiangsu Donghai Semiconductor Technology Co. Ltd has 300V peak repetitive reverse, operating peak reverse and DC blocking voltage, and 45A repetitive peak surge current. Junction operating temperature is -55 to 150 C.

The supplier requires a minimum order of 1,000 units. Delivery lead time is seven days.

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Rectifier, has 50, 75ns recovery time

Shenzhen Canyi Technology Co. Ltd's US2A Thru US2M fast-recovery rectifier has 50 to 1,000V maximum repetitive peak reverse and DC block voltage, 35 to 700V maximum rms voltage, and 2A maximum average forward rectified and 50A peak forward surge currents. Recovery time is 50 or 75ns and operating temperature -50 to 150 C.

An order of at least 1,000 units is required for delivery within three days.

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