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The Recycling of Agglomerate Abrasive Slurry

IP.com Disclosure Number: IPCOM000238068D
Publication Date: 2014-Jul-30
Document File: 4 page(s) / 55K

Publishing Venue

The IP.com Prior Art Database

Abstract

Two recycling process for an agglomerate slurry are presented. The first is an in-situ process, where the slurry is recovered at the point of use, i.e. the polishing/lapping tool, and reused, generally by blending it with a fraction of new slurry. The second process is an ex-situ process where components of the used slurry, e.g. solvent and abrasive agglomerates and their corresponding abrasive particles (typically diamond), are separated from the slurry, purified and reused in the manufacture of new slurry.

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Page 01 of 4

The Recycling of Agglomerate Abrasive Slurry

Abstract:

    Two recycling process for an agglomerate slurry are presented. The first is an in-situ process, where the slurry is recovered at the point of use, i.e. the polishing/lapping tool, and reused, generally by blending it with a fraction of new slurry. The second process is an ex-situ process where components of the used slurry, e.g. solvent and abrasive agglomerates and their corresponding abrasive particles (typically diamond), are separated from the slurry, purified and reused in the manufacture of new slurry.


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Background:

    The development of industrial quantities of single crystal sapphire has lead to the need for effective cutting, grinding and polishing of large areas of sapphire. Large sapphire wafers are needed for LED substrates and there is an increasing desire to use sapphire windows and optics where abrasion resistance is desired.

    Glass bonded diamond agglomerates may be used in an organic fluid to form a polishing slurry. Minor amounts of alumina may also be included in the slurry or on the surface of the agglomerates. One version of this slurry consists of approximately 1% agglomerates in Tri- ethylene glycol. This is used in a polishing step just before the final Chemical Mechanical Polishing (CMP) of the sapphire. The cost effectiveness of this slurry can be increased by in-situ and ex-situ recycling of the slurry. During the polishing with the composite abrasive slurry, the agglomerates break down as they polish the sapphire. Some of the agglomerates will survive and can be recycled. The recycling of agglomerates at the polishing location is referred to as in-situ recycling and used slurry that is reprocessed at a different location is referred to as ex-situ recycling.

In Situ Slurry Recyling:

    Recycling at the polishing machines may be as simple as collecting the effluent from the polishing machines and pumping it back into the same or another polishing machine. More consistent results will be achieved using more complex recycling process.

Figure 1.


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Fig. 1 shows a flow diagram of an in-situ recycling process, a controlled mix of new and used slurry is used in the polishing process. A simple screen filter is used to remove any large swa...