博士 / 國立成功大學 / 工程科學系碩博士班 / 97 / With the evolution of high speed circuits and higher CPU clock frequency, cooling modules are necessary for electronic systems. However, the configurations of the cooling modules such as heatsinks, heatpipes, may induce EMC problems. In this study, the electromagnetic effect of pin-fin heatsinks is investigated by solving Maxwell equations numerically using a FDTD method and PML boundary conditions. Three types of excitation sources with different operating frequencies are explored. For suppressing the EM effects of fins, grounding methods by using metal slabs are also examined.
For the effect of excitation sources, resonant behaviors triggered by Modulated Gaussian Pulse occur at specific frequencies. For Differentiated Gaussian Pulse, the distribution of resonant points shows cluster phenomena due to the peaks of the source when the reference operating frequency is increased to 4GHz. Also, an EM empty bandwidth exists which shifts with the operating frequency. For the Smooth Compact Pulse excitation source, quite a few multiple resonant frequencies are observed at higher operating frequencies.
Among the heatsinks, the 6x6 pin-fin heatsink is most liable to EM energy to induce EM resonance. Using a metal block as a heatsink at higher operating frequencies should be avoided as it may induce undesirable EM effects.The 3x3 pin-fin heatsink can suppress the Z-direction electric field. No matter what the excitation source is, the absorption magnitudes of the fins are much larger than those due to radiation.
For grounding methods with metal slabs, the scheme is effective in suppressing emissions at higher frequencies. Different grounding configurations for the 6x6 pin-fin heatsink show that the EM resonant magnitude can be reduced by 1.4 times at 1GHz operating frequency. The resonant points can be changed by the fin cavity characteristics by using surrounded grounding method. As for the embedded grounding model, the scheme can suppress emissions up to 8GHz. For the slit grounding model, the adverse EM effect can be decreased by 4 times at low operating frequency. Additionally, this grounding configuration can make the resonant pulse more smoothly and suppress the high frequency resonance more effectively.
| Identifer | oai:union.ndltd.org:TW/097NCKU5028001 |
| Date | January 2008 |
| Creators | Shih-bin Chiu, 邱世彬 |
| Contributors | Jung-hua Chou, 周榮華 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 178 |
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