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Method to Align Large Areas within Fractions of a UM to a Given Reference Plane

IP.com Disclosure Number: IPCOM000112687D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Miersch, EF: AUTHOR

Abstract

This publication relates to the task of smoothing out the 8 um thick machinable surface of a relatively thin (5 mm) non-parallel, non-flat substrate with a diameter of larger than 180 mm to within a 1 um value, given by the milling accuracy tolerance of the u-milling machine. It is assumed that the Substrate Surface Layer (SSL), to be machined, is slightly thicker than the variation in flatness of the SSL, measured as the distance between its highest peak and deepest valley. In order to align a nonparallel substrate to the cutting plane of the surface to be machined, ultra precision alignment fixtures were used in form 3 point z-stages. However, the alignment had then to be fixed by a rigid holder which had to keep the substrate in place during machining.

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Method to Align Large Areas within Fractions of a UM to a Given Reference
Plane

      This publication relates to the task of smoothing out the 8 um
thick machinable surface of a relatively thin (5 mm) non-parallel,
non-flat substrate with a diameter of larger than 180 mm to within a
1 um value, given by the milling accuracy tolerance of the u-milling
machine.  It is assumed that the Substrate Surface Layer (SSL), to be
machined, is slightly thicker than the variation in flatness of the
SSL, measured as the distance between its highest peak and deepest
valley.  In order to align a nonparallel substrate to the cutting
plane of the surface to be machined, ultra precision alignment
fixtures were used in form 3 point z-stages.  However, the alignment
had then to be fixed by a rigid holder which had to keep the
substrate in place during machining.  The forces needed to keep the
substrate in place bent even the 6 mm thick alumina substrates by 30
um and more.  The alignment procedure is very time consuming and,
finally, even the "waxing" of the part to a thick base plate and
heavy holders for this base plate could not eliminate the vibrations
of the part during machining totally.

      With the help of two machinable vacuum chucks, this problem can
be solved, eliminating all time-consuming precision alignments and
the possibility of the machined part to vibrate during machining.

      In the technique, a two-sided vacuum machinable vacuum chuck,
sitting on the...