Apparatus for mixing liquids in a certain ratio
US5346302A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 21, 1991 |
| Grant date | Sep 13, 1994 |
| Priority date | — |
| Expiry date | Nov 21, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05D11/134
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for mixing a deionized water and a hydrofluoric acid precisely in the ratio of 100:1, so as to produce a mixture which are properly used in etching wafters. The mixing apparatus comprises a self-lubricating plastic container of a double construction which enables to obtain a more precise quantity of liquid. The mixing apparatus also comprises an electronic balance measuring the weight of the liquid mixture, an indicator indicating numerically the weight measured by the balance, a mixing tank mixing the liquids, and control valves supplying the liquids in large and small quantities, respectively. According to this arrangement, it is possible to obtain a mixture of a large quantity liquid or a small quantity liquid in a precise mixing ratio with a tolerance of within 1%. Thereby, any poor etching of wafers can be avoided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.