gesponsertSecond sourcing in power semiconductors A second MOSFET is not yet an alternative

Fetek wants to establish itself in Europe as an application-driven silicon power MOSFET supplier and second-source partner for power semiconductor applications. Rather than focusing on record-breaking specifications, the company emphasizes a practical balance between efficiency, thermal performance, packaging, supply stability and cost competitiveness.

When a MOSFET has to be replaced, the search often starts with a few familiar values: blocking voltage, current, RDS_(on) and package. If another device with similar specifications is available, the solution may initially look straightforward. The data sheet alone, however, does not determine whether the new device is a real alternative.

Gate charge, capacitances, switching behavior, thermal characteristics and safe operating area may all differ. Two devices can look similar on paper and still behave differently in an existing design. And even a technically suitable MOSFET is of little use if the new supplier cannot deliver a few months later.

This is where Fetek is trying to position itself. According to the Taiwanese fabless company, its current focus is mainly on silicon power MOSFETs. What stands out is less a single technical record than the way Fetek describes its development target. The aim is not simply to push RDS_(on) lower or switching speed higher, but to achieve a workable balance between efficiency, thermal behavior, packaging, supply and cost.

That sounds less spectacular than many semiconductor roadmaps. In a real design, it may matter more.

The best single value is not enough

According to Fetek, current development is focused primarily on low- and medium-voltage MOSFETs based on shielded-gate-trench technology. The latest generations are intended to combine lower conduction losses with improved switching behavior, better thermal performance and a wider safe operating area.

Low RDS_(on) remains important because it reduces losses in the conducting state. In a fast-switching converter, however, it is not the only relevant value. Gate charge and the dynamic behavior of the transistor also affect losses. Depending on the application, an improvement in one area can therefore be partly offset by a disadvantage elsewhere.

Fetek describes this balance as one of its main development targets. Detailed device-level comparisons depend strongly on the target application, operating conditions and design requirements. The written answers do not include a specific before-and-after data set, so for engineers the real evaluation begins with the actual device – including RDS_(on), gate charge, switching behavior, thermal performance and safe operating area.

AI, but only where silicon makes sense

Fetek lists DC-DC converters and power distribution in PCs, notebooks, drones and battery backup units among the applications for its low- and medium-voltage MOSFETs. In AI infrastructure, the company focuses on selected power stages rather than positioning its MOSFETs as a general AI solution.

The company does not, however, turn this into a general AI story. For data centers, Fetek points to specific power stages such as DC-DC conversion, power distribution and auxiliary supplies. These applications combine high currents and increasing power density with limited space and corresponding cooling requirements. Low losses help, as long as the switching behavior also suits the application.

Fetek also names new-energy vehicles, robotics, industrial automation, energy infrastructure, aerospace, and conventional information and communications technology as markets that are expected to influence product development. Much of this is not exotic. These are mainly applications in which efficient power conversion is required in an increasing number of places.

Silicon is set to remain the core technology for now. According to Fetek, higher voltage classes as well as SiC and GaN are part of its mid- to long-term power device product strategy. Silicon power MOSFETs, however, remain the company’s established core platform for current customer applications.

A second source has to do more than look similar

For Europe, Fetek puts particular emphasis on its role as an alternative supplier. The company explicitly includes design-in support, technical cooperation and second-source flexibility in its positioning.

This is where a purchasing issue becomes a technical one again. Two MOSFETs with a similar voltage class and comparable RDS_(on) do not necessarily behave in the same way. The more strongly an existing design has been optimized around one specific device, the more carefully an alternative has to be evaluated.

A true second source is therefore better qualified before a shortage occurs rather than during one. If a replacement is only tested once the original component is already unavailable, what looked like a simple component change can quickly become an engineering problem.

According to Fetek, the company wants to support customers in selecting technically suitable alternatives. For a supplier that is still far less familiar in Europe than the established MOSFET manufacturers, this is likely to be one of the key challenges. Cost competitiveness may attract initial interest, but device behavior, technical support and supply reliability are essential for a successful design-in.

Fabless means someone else has to manufacture

Supply presents Fetek with an additional challenge. As a fabless company, it cannot support its claims of availability with its own wafer fab. Wafer production, assembly and test are organized together with manufacturing partners.

According to Fetek, capacity planning therefore starts at the wafer stage. Customer demand and forecasts are intended to feed into this planning, while production and delivery schedules are tracked through wafer manufacturing, assembly and test. Inventory and early communication with customers are meant to provide additional flexibility.

The written information is not enough to judge how well this model would perform during a major supply disruption. Another point is more relevant: a company that wants to act as a second source needs more than an electrically compatible device. It also needs to explain where that device will come from two or three years from now.

For European engineers considering Fetek as an additional source, that question may ultimately matter at least as much as another incremental improvement in RDS_(on).

Building trust in the European market

Fetek names industrial electronics, energy storage, motor drives, DC-DC conversion, power distribution and selected e-mobility applications as its main European target markets. Over the next three to five years, the company says it wants to work more closely with engineers, distributors and design-in partners, while increasing its visibility at events such as PCIM Europe and electronica.

That, however, is only the beginning of the more difficult part. A semiconductor supplier that is still relatively unknown has to persuade engineers to evaluate a new device, provide samples, answer technical questions and then remain a reliable supplier for years.

Perhaps that is why Fetek’s rather unspectacular message fits the company quite well. In its answers, it does not promise a MOSFET that beats every competitor on every specification. It promises an alternative in which technology, price, support and supply are intended to fit together. Fetek sees application-driven device selection, design-in cooperation and long-term supply planning as part of that approach.

Whether that works has to be proven in the individual design.

A second MOSFET on the bill of materials is not yet a true second source. It only becomes one when it can actually be used when it is needed. (sb)

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