Electrical characteristic testing of power devices under temperature variation: the key to ensuring performance and reliability

Published: 2025-09-28 Views: 次

       In power electronics, temperature is a central concern for every design engineer. The temperature characteristics of power devices directly determine the performance, efficiency, and reliability of the entire electronic system. Testing these characteristics is not only essential for preventing thermal failure but also a key basis for optimizing system design.

Temperature characteristic testingFor power devices,reliable operation and long-term stabilityis crucial. According to statistics, of electronic equipment failures55% are caused by temperatures exceeding the specified value; as temperature increases, the failure rate of electronic equipment grows exponentially. Power devices generate a large amount of heat during operation; if heat dissipation capability is limited, the temperature of the active region of the chip inside the device and the junction temperature will rise, reducing reliability and preventing safe operation.

1 Relationship between temperature and power device reliability

The reliability of power devices is closely related to their operating temperature. Junction temperature is the actual operating temperature of the semiconductor in electronic equipment and is usually higher than the case temperature during operation. To ensure long-term normal operation of the device, a maximum allowable junction temperature Tj max must be specified; this value is determined by the device's chip material, packaging material, and reliability requirements.

Power semiconductors can suffer permanent damage during operation ifPower lossand generate heat. This heat must be effectively dissipated to the surrounding environment through heat dissipation paths; otherwise, the device temperature will continue to rise and eventuallyexceeding the safe junction temperaturecausing permanent damage. Different semiconductor materials have different temperature tolerance characteristics:

Silicon (Si) devices:The practical limit junction temperature of traditional silicon-based power devices is generally150-200℃

Silicon carbide (SiC) devices:Due to their wide bandgap characteristics,SiC devices in principle have a junction temperatureexceeding500℃can still operate normally

Gallium nitride (GaN) devices:Also a wide-bandgap semiconductor, it can operate at300℃above high-temperature conditions

2 Impact of temperature on power device performance

Temperature changes directly affect multiple key performance parameters of power devices. Understanding these effects is crucial for designing efficient and reliable power systems.

2.1 Changes in switching characteristics

Temperature rise causesreduced carrier mobility, thereby slowing the switching speed of power devices. This manifests as:

Increased switching loss:the turn-on and turn-off processes slow down, and the energy loss in each switching process increases

Operating frequency limit:In high-frequency application scenarios, temperature rise limits the maximum usable switching frequency

EMI characteristic changes:Changes in switching speed affect electromagnetic interference characteristics

SiC power devices, due to theirhigh thermal conductivity(silicon's3x), maintaining good switching performance at high temperatures and reducing switching losses。

2.2 Changes in conduction characteristics

The effect of temperature on conduction characteristics is relatively complex and varies across technologies:

IGBT：On-state voltage drop typically has anegative temperature coefficient,on-state voltage drop decreases at high temperature, which may lead to current concentration and thermal runaway risk

MOSFET：on-state resistance has apositive temperature coefficient,resistance increases at high temperatures, providing self-current-sharing characteristics that benefit parallel operation

SiC devices:the temperature coefficient of on-state resistance is relatively small, and high-temperature performance is more stable

2.3 Changes in threshold voltage

The threshold voltage of nearly all power devices decreases as temperature rises, which leads to:

Easier conduction：the device turning on at a lower gate voltage

reduced noise immunity：easy false triggering by noise, causing bridge shoot-through risk

Drive design challenges:the drive circuit needs to account for changes across the entire operating temperature range

2.4 Body diode characteristic variation

The body diode characteristics integrated in power devices also change with temperature:

Reverse recovery characteristics:Reverse recovery time and reverse recovery charge typically increase as temperature rises

On-state voltage drop:Diode forward voltage drop typically decreases as temperature rises

Table: Trends in the impact of temperature on key parameters of various power devices

3 Key Parameters and Methods of Power Device Temperature Testing

PHS Power semiconductor high-temperature test system (Power Semiconductor High-Temperature Testing System), specifically designed for power semiconductor devices (such as IGBT、SiC Mosfet), and is designed for aging tests and reliability verification of power modules, supporting rapid temperature changes and long-term constant-temperature testing. The system integrateshigh-precision heating unit TCU with intelligent temperature control algorithms,Safety test fixture与protective cover、Semiconductor Parameter Analyzerensuring temperature uniformity and stability (within ±0.2°C) during a wide range of electrical tests, andCompatible with a variety of standard fixtures，meets TO-247 packaged into a six-in-one high-power moduletesting requirements. Intelligently performs precise electrical performance measurements on power semiconductors under different temperature environments, and outputs professional reports with one clickDatesheet report.

PHS system actual test of Si device breakdown voltage at 150°C

High-temperature test fixtureHighly integrated and compact, can be vertically clamped ontoDeviceFor packaging, a "furnace cage" heating method is used, which does not interfere with the test circuit and does not contactDevicepins.

Practical application scenarios of double-pulse dynamic testing

Static testing scenario with IWATSU curve tracer

THFFixtureTriple protection for worry-free safety

Hardware protection:

1.Anti-scald housing design with internal dual-layer thermal insulation protection, maximum surface temperature70℃

2.Ergonomic 'grip cap' design allows direct handling of the fixture at high temperatures

3.Safety structure design confines thermal runaway explosions internally, with the protective cover adding an extra layer of safety

Software protection:

Software limits heating power, with intelligent protection against overcurrent and thermal runaway

Process safety protection:

Works with tester safety interlock for electrical and thermal isolation throughout testing

One-click test start via software and output of test report

IncludesTemperature characteristic curves、Parameter comparison table, conclusion page, etc.Datasheet-grade professional report

（System intelligent test software EC-200X interface)

(Actually tested IGBTs from three major manufacturers and one SiC MOSFET at 175°C)

4The value of temperature testing in power device applications

The value of power device temperature testing lies not only in preventing overheating damage, but also in providing key data support for the optimized design of the entire electronic system.

4.1 Reliability assurance and lifetime prediction

Through temperature testing, power devices can be ensured to operate within a safe temperature range, reducing quality issues and improving the reliability of electronic products. The reliability of electronic equipment is also related to components, structure, assembly, processes, and processing quality. In practical engineering applications, feedback data should also be obtained through various tests to improve the design and further enhance the reliability of electronic equipment.

Temperature test data is also acceptablefor use withLifetime prediction. The lifespan of power devices is closely related to operating temperature. According to the Arrhenius model, for every 10°C increase in temperature, device lifespan is reduced by approximately half. Through long-term temperature monitoring, the remaining lifespan of equipment can be predicted and predictive maintenance implemented.

4.2 Optimization basis for thermal design

TemperatureTest resultsprovides for thermal designOptimization basis. By measuring the temperature distribution of power devices under different operating conditions, the heat sink design, fan selection, and airflow layout can be optimized in a targeted manner, achieving the best balance between cooling performance and cost.

4.3 Maximizing system performance

Through precise temperature monitoring and control, power devices can operate atOptimal temperature range，neither overheating and affecting reliability nor running too cool and affecting performance. In some cases, appropriately raising the operating temperature may help reduce conduction losses and improve system efficiency.

Based on temperature test data, the following can be implemented:Active thermal management strategies，Such as:

Power derating: automatically reduce output power when the temperature exceeds a set threshold

Dynamic frequency adjustment:Adjust switching frequency according to temperature changes to balance switching losses and conduction losses

Cooling control:Intelligently control the operating status of the cooling system (such as fans and water pumps) according to temperature requirements

4.4 Condition monitoring and fault warning

Temperature characteristics can serve asCondition monitoringAn important indicator. Abnormal temperature rises often indicate potential faults, such as:

Solder layer degradation:causes increased thermal resistance, with junction temperature rising while case temperature rise is not obvious

Bond wire lift-off:causing increased local current density and hotspot formation

Aging failure:Device parameter degradation leads to increased losses and abnormal temperature

By continuously monitoring temperature change trends, potential faults can be detected early, preventive maintenance implemented, and unexpected downtime avoided。

5 Conclusion

Temperature characteristic testing of power devices is fundamental work for ensuring the reliability and performance of power electronic systems. With thewide-bandgapWith the rapid development of semiconductor technology, the operating temperature of power devices continues to rise, placing higher demands on temperature testing technology.

Leading manufacturers such as Infineon and ROHM have developed, through continuous innovation, fromFrom chip technology and packaging processes to thermal management strategiesa complete set of solutions, enabling power devices to operate reliably at higher temperatures. However, accurate testing of temperature characteristics and effective thermal management remain key challenges in power electronic system design.

In the future, power device temperature testing technology will develop towardHigher precision, faster response, and more comprehensive integrationthe direction of。online monitoring, intelligent prediction, and active thermal managementwill become standard features, enabling power electronic systems to operate reliably under harsher temperature conditions while achieving higher efficiency and power density.

For power electronics engineers, mastering the principles and methods of power device temperature characteristic testing and understanding the latest technology trends are essential skills for designing efficient and reliable power systems. Only through accurate temperature testing and effective thermal management can the performance potential of power devices be fully realized and long-term reliable operation of electronic equipment ensured.