Inductive Coupled Plasma Etching of High Aspect Ratio Silicon Carbide Microchannels for Localized Cooling

2015 ◽  
Author(s):  
Karen M. Dowling ◽  
Ateeq J. Suria ◽  
Yoonjin Won ◽  
Ashwin Shankar ◽  
Hyoungsoon Lee ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Inductively Coupled Plasma ◽  
Hot Spot ◽  
Transfer Coefficients ◽  
Inductively Coupled ◽  
Heat Transfer Coefficients ◽  
Icp Etching ◽  
On Chip

High aspect ratio microchannels using high thermal conductivity materials such as silicon carbide (SiC) have recently been explored to locally cool micro-scale power electronics that are prone to on-chip hot spot generation. Analytical and finite element modeling shows that SiC-based microchannels used for localized cooling should have high aspect ratio features (above 8:1) to obtain heat transfer coefficients (300 to 600 kW/m2·K) required to obtain gallium nitride (GaN) device channel temperatures below 100°C. This work presents experimental results of microfabricating high aspect ratio microchannels in a 4H-SiC substrate using inductively coupled plasma (ICP) etching. Depths of 90 μm and 80 μm were achieved with a 5:1 and 12:1 aspect ratio, respectively. This microfabrication process will enable the integration of microchannels (backside features) with high-power density devices such as GaN-on-SiC based electronics, as well as other SiC-based microfluidic applications.

Manufacture of High Aspect Ratio Bulk Titanium Micro-Parts by Inductively Coupled Plasma Etching

2008 ◽  
Author(s):  
Gang Zhao ◽  
Qiong Shu ◽  
Yue Li ◽  
Jing Chen
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Inductively Coupled Plasma ◽  
Etching Rate ◽  
Sidewall Roughness ◽  
Inductively Coupled ◽  
Icp Etching ◽  
Novel Technology ◽  
Micro Parts ◽  
Etching Mask

A novel technology is developed to fabricate high aspect ratio bulk titanium micro-parts by inductively coupled plasma (ICP) etching. An optimized etching rate of 0.9 μm/min has been achieved with an aspect ratio higher than 10:1. For the first time, SU-8 is used as titanium etching mask instead of the traditional hard mask such as TiO2 or SiO2. With an effective selectivity of 3 and a spun-on thickness beyond 100 μm, vertical etching sidewall and low sidewall roughness are obtained. Ultra-deep titanium etching up to 200 μm has been realized, which is among the best of the present reports. Titanium micro-springs and planks are successfully fabricated with this approach.

Impact of Turbulator Design on the Heat Transfer in a High Aspect Ratio Passage of a Turbine Blade

2014 ◽  
Author(s):  
S. Naik ◽  
S. Retzko ◽  
M. Gritsch ◽  
A. Sedlov
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Transfer Coefficient ◽  
High Aspect Ratio ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients ◽  
Trailing Edges

The trailing edge region of gas turbine blades is generally subjected to extremely high external heat loads due to the combined effects of high mach numbers and gas temperatures. In order to maintain the metal temperatures of these trailing edges to a level, which fulfils both the part mechanical integrity and turbine performance, highly efficient and reliable cooling of the trailing edges is required without increasing the coolant consumption. In this paper, the heat transfer and pressure drop characteristic of three different turbulator designs in a very high aspect ratio passage have been investigated. The turbulator designs included angled and tapered ribs, broken discrete ribs and V-shaped small chevrons ribs. The heat transfer and pressure drop characteristics of all the turbulator configurations was initially investigated via numerical predictions and subsequently in a scaled experimental perspex model. The experimental study was conducted for a range of operational Reynolds numbers and the TLC (thermochromic liquid crystal) method was used to measure the detailed heat transfer coefficients on all surfaces of the passage. Pressure taps were located at several locations within the perspex model and both the local and average heat transfer coefficients and pressure loss coefficients were determined. The measured and predicted results show, that for all cases investigated, the local internal heat transfer coefficient, which is driven by the highly three dimensional passage flows, is highly non-uniformly within the passage. The highest overall average heat transfer was obtained for the angled and tapered turbulator. Although the average heat transfer coefficient of the discrete broken turbulator and the small chevron turbulator were slightly lower than the baseline case, they had much higher pressure losses. In terms of the overall non-dimensional performance index, which incorporates both the heat transfer and the pressure drop, it was found that the angled and tapered turbulator gave the best overall performance.

Sign in / Sign up

Export Citation Format

Share Document