Browse Prior Art Database

Air Bearing Module Alignment

IP.com Disclosure Number: IPCOM000040233D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Smith, GM: AUTHOR

Abstract

Printed circuit cards are now using surface mount modules of increasing physical size and pin count, and decreasing pin pitch. The fineness of pitch and the resulting fragility of the pins is leading to the increasing use of vision techniques for inspection of the pins before assembly and for the determination of exact module position to allow accurate placement on the board. However, to get maximum resolution in any vision system used, it is necessary to fill the camera field of view as fully as possible. Due to the fragility of the module pins, the packaging methods usable for these modules are limited, and so they are supplied in thin plastic vacuum-formed waffle sheets, often containing 60 modules per sheet.

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Air Bearing Module Alignment

Printed circuit cards are now using surface mount modules of increasing physical size and pin count, and decreasing pin pitch. The fineness of pitch and the resulting fragility of the pins is leading to the increasing use of vision techniques for inspection of the pins before assembly and for the determination of exact module position to allow accurate placement on the board. However, to get maximum resolution in any vision system used, it is necessary to fill the camera field of view as fully as possible. Due to the fragility of the module pins, the packaging methods usable for these modules are limited, and so they are supplied in thin plastic vacuum-formed waffle sheets, often containing 60 modules per sheet. The cumulative position error possible and the difficulty of locating so flimsy packaging material make it imperative to provide some additional module-locating method. A method which is well known is to pick up each module by vacuum gripper, position in some jig, release the module, mechanically adjust the position of the module and re-pick it, now in a known and repeatable location. This type of alignment is not sufficiently accurate to make unnecessary the vision location, due to the poor tolerancing between the module body and the pins, but it is quite good enough to ensure that the field of view of the camera is filled. This article describes a different method of performing the type of mechanical alignment described abov...