Glass Mask Loading Tool
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Christmas, HF: AUTHOR [+3]
Described is a hardware implementation to provide a Glass Mask Loading Tool (GMLT) to perform cleaning, identifying and loading glass masks into their cassettes. The tooling eliminates manual operations, removes hazardous and chemical exposure, increases overall operator safety, decreases product contamination and increases process control and yield.
Glass Mask Loading Tool
a hardware implementation to provide a Glass Mask
Loading Tool (GMLT) to perform cleaning, identifying and loading
glass masks into their cassettes. The tooling eliminates manual
operations, removes hazardous and chemical exposure, increases
overall operator safety, decreases product contamination and
increases process control and yield.
introduction of dry glass mask/copper sheet
manufacturing, as used in the fabrication of Multi-Layer Ceramic
(MLC) circuit boards, a tool was required to perform the glass mask
cleaning, identifying, and loading the glass masks into their
Part of the
MLC boards involves the fabrication of "green"
sheets which become the layers in the MLC "brick". The "lands" for
the sheets are deposited through a silk-screening type of process,
where a thin copper sheet is used as the silk-screen. The pattern on
the copper sheets is made by a photo-resist etching process. In
turn, the photo-resist pattern is developed by exposure through a
glass mask. Since both sides of the copper sheet must be exposed,
the glass masks come in matched pairs. Due to the uniqueness of the
individual green-sheet layers and the number and complexity of the
various ceramic bricks, there are many glass mask pairs which must be
kept on file and used as dictated by a given "batch-job" order
In prior art,
the copper sheet's photo-resist was layered using
a manual, liquid depositing, rolling process. This wet method
involved the use of potentially hazardous chemicals and their use and
disposal posed environmental exposure problems. For these reasons,
an alternative process, or "dry" process, was developed involving the
manual layering of a thin film of photo-resist onto copper sheets.
described herein improves on the prior art process
by keeping the paired glass masks within sealed cassette assemblies.
The process involves a sealing procedure of the glass
masks since the
process had to guarantee "Class 10" specification. The glass mask
loading tool provides a unique computer controlled machine tool that
handles, transports, cleans and identifies the glass mask prior to
loading them in the glass cassette.
The GMLT is
typically located in a clean room with the work
area sealed off by an enclosure. The figure shows a front view of
the GMLT. Mounted on the top of the enclosure is a series of filters
(not shown), with deionizers to insure a steady flow of Class 10
statically-neutral air will move downward over the various stations.
The GMLT consists of nine primary assemblies: Electrical and control
cabinet 10; Readout station 11; Pickup and orientation check station
12; Part verification station 13; Deionizer rods 14; Cleaning station
15; Cassette loading station 16; Belt Drive 17; and Linear transport
for cassette base assembly 18.
After obtaining the batch-job paperwork and...