Steady R&D toward smaller resettable fuses with better reliability, stability

Resettable fuses are widely used in mobile electronics, communications equipment, computers and peripherals, automotive electronics, industrial control and other electronic equipment to ensure normal operation and protect against overcurrent and overtemperature conditions. Compared to traditional fuses, they are capable of self-recovery and display high stability and reliability, which have gained them popularity and make them likely to enter mainstream use in the next few years.

Building on these advantages, Chinese manufacturers of resettable fuses are continuing R&D efforts to match upgrades in electronics applications. They are concentrating on the realization of smaller but more robust components, specifically in-demand types for surface mounting.

The current SMD category has sizes up to 2920, with those in 0603, 0805 and 1206 dominating shipments.

The smallest, which are in 0402 packages, can be sourced from large suppliers. An example is the ASMD0402 from JDT Fuse, which is 1x0.5mm. It has low internal resistance and quick response time, and is available in various current ratings to suit computers and peripherals, laptops, tablets and hard disk drives.

Companies are also improving manufacturing techniques by introducing new production and test equipment. Shenzhen Juding has come up with a method for round types to ensure low loss while also helping boost production efficiency and reduce costs.

After a challenging 2020, suppliers interviewed by Global Sources Electronic Components are looking forward to an increase in product demand and sales in the months ahead. They are optimistic export sales growth will be between 5 and 10 percent in 2021.

China is one of the world's major sources of resettable fuses. Its hundreds of manufacturers include industry leader Littelfuse of the US, and major homegrown companies such as JDT Fuse and Sea & Land Electronics.

All suppliers also offer conventional fuses, thermal cutoffs and circuit breakers. The category accounts for 10 to 40 percent of their shipments.

Domestic enterprises, the majority of which are small or midsize, send between 30 and 80 percent of their output overseas, mainly to Europe, North America and the Asia-Pacific region. The Middle East, Russia and South America are the other destinations.

Products are shipped out of factories that are mostly in the cities of Shenzhen, Dongguan, Zhenjiang, Suzhou and Ningbo in Guangdong, or in Zhejiang and Jiangsu provinces.

More manufacturers venturing into the category will likely flock to these areas, which boast comprehensive supply chains and are where China's electronics industries gather.

SMD & DIP types

Mainstream resettable fuses from Chinese companies are available in SMD and DIP packagers.

SMD units are in sizes of 0603, 0805, 1206, 1210, 1812 and 2920. DIP variants in round and square shapes also come in various dimensions.

These fuses have 6 to 600V rated voltage, 10mA minimum rated current and less than 20sec recovery time. All bear relevant safety approvals, such as CE, CSA, cUL, TÜV and UL, and comply with RoHS.

Customization is widely accommodated and is another reason why manufacturers aiming for a wider market reach are boosting R&D. Orders based on this currently represent as much as 50 percent of aggregate shipments.

Key materials used in the production of resettable fuses include polymers, ceramics, epoxy, metal foil, copper and tin. These are obtained domestically, although buyers can specify other sources.

The cost of manufacturing inputs, which did not fluctuate much in 2020, is projected to remain stable and keep product prices at current levels, according to most suppliers interviewed. However, it is possible that some companies will lower quotes by up to 5 percent in order to attract more orders amid the intense competition.

50mA to 3.75A resettable fuse

Argo Technology Co. Ltd offers this AG-FRX-K17 resettable fuse with 60V maximum voltage, 50mA to 3.75A operating current and -40 to 85 C temperature range.

The negotiable order quantity has a seven-day delivery lead time.

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Resettable fuse, sustains 120mA

For security and alarm systems, analog and digital line cards, modems and DSLs, this Resettable Fuse-572 from Dongguan Better Electronics Technology Co. Ltd has maximum operating and interrupting voltages of 60VDC and 250VAC, and hold and trip current ratings of 120 and 240mA.

An order of at least 20,000 units is delivered within 10 days.

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Resettable fuse, in various contact capacities

In variants with contact capacity of 20A at 24VDC, 16A at 125VAC or 8A at 250VAC, this 17AM-D+PTC(Self-hold Type)-3 resettable fuse from Jiangsu Changsheng Electric Appliance Co. Ltd suits vacuums, paper shredders, garden tools and high-power pump motors. It meets CQC, VDE and UL requirements.

The 2,000-unit minimum order has a seven-day lead time.

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Resettable fuse, has 0.2A hold current

Model JK250-120U resettable fuse from Shenzhen Socay Electronics Co. Ltd has 60V maximum voltage and 0.2A hold current. It suits automotive and consumer electronics, and industrial, security and communications applications.

The negotiable order quantity has a seven-day delivery lead time.

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