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Low-Cost, High-Quality Line-Width Measurement of Recording Heads

IP.com Disclosure Number: IPCOM000040757D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Stevens, RA: AUTHOR

Abstract

This measurement process provides a selective, low-cost method of improving tester performance to overcome problems of specimen contamination, electronic fluctuation, illumination inconsistency, mechanical vibration, and optical resolution. This measurement process utilizes data intrinsic to the manufacturing process for selective reinspection of parts. Inspection of critical line-width dimensions is required after fabrication of ferrite sliders (see Fig. 1). A slider is sometimes referred to as a "head". This is the element used to read and write to magnetic disks. Currently, the line-width dimensions are measured on an Automated Inspection Microscope (AIM). (Image Omitted) All fabrication of the sliders is done on groups of twelve transfer tools called a "fixture" or "nest".

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Low-Cost, High-Quality Line-Width Measurement of Recording Heads

This measurement process provides a selective, low-cost method of improving tester performance to overcome problems of specimen contamination, electronic fluctuation, illumination inconsistency, mechanical vibration, and optical resolution. This measurement process utilizes data intrinsic to the manufacturing process for selective reinspection of parts. Inspection of critical line-width dimensions is required after fabrication of ferrite sliders (see Fig.
1). A slider is sometimes referred to as a "head". This is the element used to read and write to magnetic disks. Currently, the line-width dimensions are measured on an Automated Inspection Microscope (AIM).

(Image Omitted)

All fabrication of the sliders is done on groups of twelve transfer tools called a "fixture" or "nest". A fixture carries 96 sliders in a 12 x 8 matrix (see Fig. 2). Sliders are bonded to metallic bars called "transfer tools"; each transfer tool carries eight sliders. A description of the method, generalized and tester-independent, follows. A flow diagram (see Fig. 3) parallels the description for clarity. 1. Given a matrix of 12 x 8 sliders (see Fig. 2), gap

widths within a column of 8 tend to be bounded in

width by the nature of the manufacturing process.

2. An estimate of standard deviation for the entire

fixture "nest" can be obtained by the formula s(x)

:= Rbar/D2, where D2 is a factor used for

computing an estimate of standard deviation for

sample size 8. This factor accounts for variation

in the range as sample size changes. It is used

almost exclusively in quality control work and a

description may be found in standard quality

control training texts. Note that this formula

assumes sample randomness which may seem

contradictory to the bounds established in the

previous ite...