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Sep 25, 2022 434 likes •658 views

Single-Mask Fabrication of Temperature Triggered MEMS Switch for Cooling Control in SSL System J. Wei, H. Ye , H.W. van Zeijl, P.M Sarro, G.Q. Zhang Delft University of Technology, Dimes Materials innovation institute, M2i What is SSL? Solid

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Single-Mask Fabrication of Temperature Triggered MEMS Switch for Cooling Control in SSL System

J. Wei, H. Ye, H.W. van Zeijl, P.M Sarro, G.Q. Zhang

Delft University of Technology, Dimes Materials innovation institute, M2i

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H.Ye (叶怀宇)

What is SSL?

Solid State Light || Light Emit Diode Serve Light

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H.Ye (叶怀宇) Page 3

Introduction
Thermal switch
Conclusions
Acknowledgements

Outline

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Incandescent bulb to LED

More efficiency (6 times)
Long life time (5 years or more)
Energy saving

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H.Ye (叶怀宇)

LED package suffers high temperature
For other higher power SSL, even worse

Heat in LED

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Why thermal management?

For 5K difference, lumen output of blue light LEDs will decrease 4% and

lifetime drops from 60,000 down to 50,000 hours

Required temperature of LED(Lower than 150˚C)
Required temperature of Driver(Lower than 100˚C)

Reference: Che Cheung, Brandon Noska and Kim van der heide, “Thermal management: Comparison of passive and active cooling effectiveness.” LED Professional Review, (2009) pp. 42.

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Active cooling has been applied to LEDs
Intelligent temperature control system needed

AVR based intelligent temperature monitoring and control system

Thermal management

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H.Ye (叶怀宇)

Concept

Smart
> switch on/off the cooling system

based on Temperature

Small
> can be put it very close to the LED
Suitable -> easy to be integrated
> fabricated by Si micromachining

technology

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H.Ye (叶怀宇)

Technology

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V-shape thermal actuator

Local heating by electrical current
Temperature difference
Local expansion

Displacement is a function of ∆T Not suitable for uniform heating Temperature Triggered Switch

Uniform temperature distribution

A larger CTE is required on the actuation beam than

the substrate (anchor)

Aluminium/Silicon combined beam is used.

Displacement is a function of absolute T

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H.Ye (叶怀宇)

Design with parameter analysis

– Initial distance between plate and electrodes – Length of the beam – Ratio of the Al/Si

Simulation and results

Thermal switch

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H.Ye (叶怀宇)

Thermal switch

Process

– single-mask

deep reactive-ion etching (DRIE)
thermal oxidation

– Thin silicon-1.5 μm

aluminum deposited on the side wall
thin titanium nitride (TiN)

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Thermal switch

SEM (Dimension: 1.0x0.4 mm2)
Size
\height 30um

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Thermal switch

Testing with increasing temperature
The physical contact around 130ºC

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Thermal switch

Validation of concept

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Thermal switch

Video
Thermal switch on/off at designed temperature

threshold

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Conclusion

– 1.Concept of simple and smart control for SSL

A cost-effective temperature trigger for cooling control

– 2. Design and process

A single-mask 3D micro-machining process

– 3. Concept validation – 4. Further work

A functional LED package

The concept and process could be developed for other applications

Further development of the temperature trigged switch

concept and fabrication process for other applications

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Acknowledgement

The authors would like to acknowledge the technical staff of DIMES-ICP group for their precious help. This research is supported by the Enlight project (http://www.enlight-project.eu/), funded by ENIAC.

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Thank you!!!

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Cross-section SEM

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Cross-section SEM

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Cross-section SEM

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