A Flip Chip Package for Thermal Mass Flowmeter

Hui Cao, Zhiyin Gan, Xiaobing Luo, Boling Yu, Sheng Liu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


This paper reports on a new package of thermal mass flow meter. The new package is to etch a flow channel on the Al2O3 substrate, and bond the chip to the substrate using flip chip technology. The fluid flows along with the channel and across the sensor element which is made by platinum and this material's resistance changes with the temperature. When fluid flows, there will be a Δ T between upstream element and downstream element, which will result in a Δ R and Δ U, therefore we can measure Δ U to measure the fluid velocity. The velocity distribution in the channel is simulated by software Fluent. A conclusion that there is a fixed velocity ratio between the fluids inside and outside the channel is obtained. This sensor chip is fabricated using bulk micromachining technology on a silicon substrate. As the thermal layer platinum and the insulation layer silicon nitride are very thin and fragile, the nitrogen is charged in the sensor chip's cavity to form a preliminary pressure on the back of the membrane. The fabrication process is presented in the paper. Using flip chip bonding overcomes the drawbacks associated with presently available flow sensors which use wire bonding.

Original languageEnglish
Title of host publication2006 7th International Conference on Electronics Packaging Technology, ICEPT '06
PublisherIEEE Computer Society
Number of pages4
ISBN (Electronic)142440620X
ISBN (Print)1424406196, 9781424406203
Publication statusPublished - 26 Aug 2006
Externally publishedYes
Event7th International Conference on Electronics Packaging Technology - Shanghai, China
Duration: 26 Aug 200629 Aug 2006
Conference number: 7


Conference7th International Conference on Electronics Packaging Technology
Abbreviated titleICEPT '06


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