Etching a substrate: processes – Forming or treating cylindrical or tubular article having... – Forming or treating liquid transfer cylinder or tubular...
Patent
1997-07-14
2000-05-30
Gulakowski, Randy
Etching a substrate: processes
Forming or treating cylindrical or tubular article having...
Forming or treating liquid transfer cylinder or tubular...
216 24, 73 2335, B01D 1508
Patent
active
060687800
ABSTRACT:
A micro-miniature gas chromatograph column is fabricated by forming matching halves of a circular cross-section spiral microcapillary in two silicon wafers and then bonding the two wafers together using visual or physical alignment methods. Heating wires are deposited on the outside surfaces of each wafer in a spiral or serpentine pattern large enough in area to cover the whole microcapillary area inside the joined wafers. The visual alignment method includes etching through an alignment window in one wafer and a precision-matching alignment target in the other wafer. The two wafers are then bonded together using the window and target. The physical alignment methods include etching through vertical alignment holes in both wafers and then using pins or posts through corresponding vertical alignment holes to force precision alignment during bonding. The pins or posts may be withdrawn after curing of the bond. Once the wafers are bonded together, a solid phase of very pure silicone is injected in a solution of very pure chloroform into one end of the microcapillary. The chloroform lowers the viscosity of the silicone enough that a high pressure hypodermic needle with a thumbscrew plunger can force the solution into the whole length of the spiral microcapillary. The chloroform is then evaporated out slowly to leave the silicone behind in a deposit.
REFERENCES:
patent: 5192406 (1993-03-01), Woolley
patent: 5575929 (1996-11-01), Yu
patent: 5583281 (1996-12-01), Yu
patent: 5589083 (1996-12-01), Ahn et al.
Ahmed Shamim
Carnahan L. E.
Gulakowski Randy
The Regents of the University of California
Thompson Alan H.
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