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Printed Circuit Line Height Measuring Techniques

IP.com Disclosure Number: IPCOM000043919D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Ashley, DJ: AUTHOR [+4]

Abstract

A device is designed whereby the height of printed circuit lines can be measured using a light-sectioning method. The device projects images, which are visually perceived by an operator via an existing microscope, but can be adapted for video imaging usage as well as for checking the component mounting height. The objective lens 11 (Fig. 1) focuses the reticle 12 pattern onto target surface 15. The microscope superimposes target image 15 with pattern 13 on reticle 14 whereby an operator can make a comparison to determine z displacement. Two parallel light sections are projected to be used in reference with each other for threshold measurements, thus improving the speed and ease of measurement. The device is also equipped with a rotatable reticle holder (Fig.

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Printed Circuit Line Height Measuring Techniques

A device is designed whereby the height of printed circuit lines can be measured using a light-sectioning method. The device projects images, which are visually perceived by an operator via an existing microscope, but can be adapted for video imaging usage as well as for checking the component mounting height. The objective lens 11 (Fig. 1) focuses the reticle 12 pattern onto target surface 15. The microscope superimposes target image 15 with pattern 13 on reticle 14 whereby an operator can make a comparison to determine z displacement. Two parallel light sections are projected to be used in reference with each other for threshold measurements, thus improving the speed and ease of measurement. The device is also equipped with a rotatable reticle holder (Fig.
2) which allows planar images to be focused onto the target surface 15. Lines on the circuit board, lying in the x, y plane, are generally aligned along either the x or the y axis so the device consists of two light section projectors mounted 90 degrees from each other about the z axis. Both projectors have an incident angle R1 to the circuit board surface of 45 degrees. The microscope axis is perpendicular to the target surface, causing the lateral displacement to equal the height of a particular topology. The double light section method makes use of the relationship between two parallel light sections (Fig. 3). The projector is rigidly mounted to a microscope frame of reference and calibrated to focus in the same plane as the microscope. Variations between operator eyesight can be adjusted by eyepiece positions or by the addition of a rack and pinion z adjustment to the light section mechanic...