Thermal mass flow meter
US4542650A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 26, 1983 |
| Grant date | Sep 24, 1985 |
| Priority date | — |
| Expiry date | Aug 26, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/6965
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The flow meter (10), particularly useful in monitoring flow in semiconductor manufacturing operations, measures mass flow rate of fluids and is fabricated by providing spaced webs (16) deposited on a silicon substrate (11) and fluid flow grooves (13) etched across a substrate surface and extending under the spaced webs. The webs 16 include a low thermal conductivity layer deposited in spaced aligned portions of the substrate and electrically resistive pathways deposited on the layer portions (61). The webs act as temperature sensors and/or heaters. Heat is added to the flowing fluid and a differential temperature is measured on a bridge circuit as is known in the art to measure flow rate. A cover (12) has etched grooves (14a) which match the grooves (13) of the substrate to form a fluid passageway in which the web bisects the passageway forming an "air-foil" like bridging member extending completely across (or cantilevered across) in transverse relation to the flat sides of the substrate on either side of the groove. Normally multiple series of webs and multiple grooves are employed to provide redundancy of the flow meter channels in the event contaminants plug a particular channel…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.