Browse Prior Art Database

Controlled Area Rate Lapping

IP.com Disclosure Number: IPCOM000045459D
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Narken, B: AUTHOR

Abstract

Free abrasive lapping produces convex (5-10 Mum) surfaces, a problem which gets worse with fast lapping rates, larger areas and harder materials. This technique overcomes this problem, allowing fast lapping rates on hard (alumina) substrates and still obtain flat surfaces (less than 2 Mum).

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 82% of the total text.

Page 1 of 2

Controlled Area Rate Lapping

Free abrasive lapping produces convex (5-10 Mum) surfaces, a problem which gets worse with fast lapping rates, larger areas and harder materials. This technique overcomes this problem, allowing fast lapping rates on hard (alumina) substrates and still obtain flat surfaces (less than 2 Mum).

The problem with conventional machine lapping (Fig. 1) is not only that the abrasive is more plentiful near the edges of the part being lapped, but also the abrasive becomes less sharp as it proceeds near the center of the surface. As a result, the abrasion rate is greater near the edges, causing a convex surface. The maximum convexity obtained is a function of the abrasive and carrier liquid properties, but is limited by the transfer of pressure to the center as a function of convexity, thereby increasing the abrasion rate at the center until it has been normalized over the entire area, maintaining a fixed convexity.

The new approach here (Fig. 2) overcomes this problem by decreasing the relative time the outer edges are in contact with the lapping plate. This is accomplished by reducing the width (W) of the lapping surface to some dimension less than the size of the part to be lapped, such that the product of the abrasion rate and time (%) in contact with the lapping plate is equal for all areas. If the center area of the part being lapped is a and areas away from the center are a(2)...a(n) and the respective abrasion rates are r(1),..r(2)...r(n)...