Browse Prior Art Database

Automatic Height Sensing and Adjusting System

IP.com Disclosure Number: IPCOM000087598D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Firdaus, A: AUTHOR [+2]

Abstract

Substrate chip placement problems are caused by variations in thickness and flatness of the substrate, and by the differences caused by the product mix and fixturing flatness. These variables make it difficult to maintain the force for chip placement constant. Since these variables exist, it has been found necessary to measure the height of every chip site on the substrate and, accordingly, to adjust the placement tool parameters to guarantee placement force repeatability. This height sensing has been done in a number of different ways, for example, optically and pneumatically.

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Automatic Height Sensing and Adjusting System

Substrate chip placement problems are caused by variations in thickness and flatness of the substrate, and by the differences caused by the product mix and fixturing flatness. These variables make it difficult to maintain the force for chip placement constant. Since these variables exist, it has been found necessary to measure the height of every chip site on the substrate and, accordingly, to adjust the placement tool parameters to guarantee placement force repeatability. This height sensing has been done in a number of different ways, for example, optically and pneumatically.

Referring to the figure, the chips to be placed on the substrate are transported by a vacuum probe 10 which is also used as a vacuum height sensor. Thus, the one vacuum head on a common probe is used to sense the substrate height (Z) adjustment and to transport the chip to the measured position on the substrate.

The sequence of operation is as follows: a. The vacuum probe 10 (without the chip) is moved above the substrate 12 site to be measured and adjusted for height (Z). b. The vacuum in the probe 10 is turned on by solenoid 14. c. The motor 16 of the Z stage 18 is turned on, moving the substrate 12 up via the wormgear mechanism 20. d. As the substrate 12 reaches a height within .001 inches of the probe 10 the vacuum/electric switch 22 is triggered, generating a signal which stops the motor 16 and locks the Z mechanism 18 in position. e. The...