Questions on Semiconductor Device Selection and Real-World Application Experience

[lro]

Hello everyone,

I am currently organizing some reference materials on semiconductor device applications and would like to ask the community for some practical insights.

In different application scenarios, such as high-temperature, high-frequency, or long-term stable operation environments, which key parameters do you usually prioritize first? For example, voltage rating, power consumption, thermal design, package type, or other factors?

Also, during device selection, how do you usually balance performance, cost, supply stability, and future replaceability? Are there any practical methods or criteria you use in real projects?

 

[DanX]

I have a question. Since heat dissipation in space follows the fourth-power temperature law (Stefan-Boltzmann radiation law), would it be a viable design choice to operate chips continuously above 120°C? Is there any relevant cost-benefit analysis available?

 

[KevinK]

I have a question. Since heat dissipation in space follows the fourth-power temperature law (Stefan-Boltzmann radiation law), would it be a viable design choice to operate chips continuously above 120°C? Is there any relevant cost-benefit analysis available?

I can’t give you a detailed cost/benefit, but above 120 degrees C (nearing 400 degrees K) vs 30 degrees C (300 degrees K) is a huge jump when it comes to exponential or linear physics.

Device‑level (on‑chip)
• More leakage current and lower speed, due to decreased mobility, as temperature rises (roughly nonlinear; gets worse faster at higher temps).
• Metal lines wear out faster (electromigration) with higher temperature (often approximated as exponential; a common rule of thumb is about 2× faster wear per ~10 °C).
• Transistors and gate oxides age and drift faster as temperature rises (generally modeled as exponential vs temperature in reliability calculations).
Board‑level (PCB, vias, solder)
• Vias and copper traces crack more over time as temperature and cycling increase, especially where different materials or regions expand and contract by different amounts (non‑uniform CTE causes local stress and accelerates cracking; behavior is strongly accelerated rather than linear).
• Boards warp more and stress components at higher temperatures because layers and areas with different materials or copper density expand and contract unevenly; the resulting non‑uniform bending grows roughly with temperature, while damage probability from repeated cycles follows more accelerated, nonlinear behavior.
• Solder joints creep and crack faster at higher temperatures, and they see extra shear/tensile stress when components and board expand and contract differently; time‑to‑failure is typically treated as exponentially accelerating with temperature, not just linear.
System‑level (overall reliability and behavior)
• Overall failure rate increases with temperature; many key failure mechanisms are modeled so that hazard rate grows roughly exponentially as temperature rises.
• Risk of thermal runaway rises sharply because hotter devices leak more and dissipate more power, creating a nonlinear positive feedback loop once certain temperature thresholds are exceeded.
• Different parts of the system age at different speeds due to hotspots and local material differences, since the higher local temperatures cause locally higher (often exponential) acceleration of wear‑out even when average temperature seems acceptable.