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The Key Role of Molybdenum-Copper Alloys in MOSFET Packaging

Metal-oxide-semiconductor field-effect transistors (MOSFETs) are widely used in power electronics, communication equipment, automotive electronics, and industrial control due to their high-speed switching, low on-resistance, and high-efficiency energy conversion. 

However, MOSFETs generate a lot of heat in high-power applications, which can affect their performance and lifetime if heat dissipation is not dissipated in a timely manner.

Therefore, the choice of encapsulation material is crucial. In MOSFET packaging, molybdenum-copper (Mo-Cu) alloy has become one of the key packaging materials due to its excellent thermal conductivity, low coefficient of thermal expansion (CTE) and good mechanical properties.

In high-power and high-frequency applications, MOSFET packages need to meet the following requirements:

1. High thermal conductivity

Since MOSFETs generate heat during operation, the package material needs to have good thermal conductivity to quickly conduct heat to the heat sink and prevent the device from overheating.

2. Low thermal expansion coefficient matching

MOSFET chips are typically made of silicon (Si) or silicon carbide (SiC) with a low coefficient of thermal expansion (CTE) (Si around 2.6 × 10⁻⁶/K). The CTE of the encapsulation material should be matched to the chip to reduce the interfacial stress generated during thermal cycling and improve reliability. 

3. High mechanical strength and stability

MOSFET packaging materials need to have good mechanical strength to cope with mechanical stress during the packaging process and in the working environment to prevent cracking or damage.

4. Excellent electrical properties

MOSFETs operate under high-frequency, high-power conditions, and the packaging material should have good conductivity, reduce parasitic resistance and power dissipation, and improve power conversion efficiency.

The main application components of molybdenum-copper alloys in MOSFET packages include:

1.Heat Spreader

When MOSFETs are operating at high power, the role of heat sinks is crucial. As a heat sink material, Mo-Cu alloy can efficiently conduct the heat generated by MOSFETs, reduce chip temperature, and improve work efficiency.

2.Substrate

In MOSFET packages, the Mo-Cu alloy substrate acts as a thermal buffer between the chip and the heat sink.

Due to its good thermal expansion matching, Mo-Cu substrates can effectively reduce interfacial thermal stress and extend the service life of MOSFETs.

3.Lead Frame

Mo-Cu alloys can be used in the lead frame of MOSFET packages to provide reliable mechanical support for the chip while ensuring low losses in current transmission.

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