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Three Point Tab and Slot Printed Circuit Board Alignment Method for Sheet Metal Card Enclosures

IP.com Disclosure Number: IPCOM000121784D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 4 page(s) / 99K

Publishing Venue

IBM

Related People

Ashton, GL: AUTHOR [+2]

Abstract

Alignment of the printed circuit board to the card enclosure is critical to the mating of the card connector to the board connector. For card enclosures made from sheet metal, the alignment is difficult to achieve as accurately as with a molded plastic or a die cast card enclosure. The reason is due to features used for alignment (such as holes or slots) which are punched into the sheet metal prior to forming. This makes close tolerances for these alignment features difficult to achieve. Also, additional hardware for alignment is required to be attached to either the card enclosure or the board, such hardware including dowel or alignment pins that are either press fit or attached with a fastener. Perpendicularity of these pins is also a problem due to the relatively small material thickness of the sheet metal.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 54% of the total text.

Three Point Tab and Slot Printed Circuit Board Alignment Method for
Sheet Metal Card Enclosures

      Alignment of the printed circuit board to the card
enclosure is critical to the mating of the card connector to the
board connector.  For card enclosures made from sheet metal, the
alignment is difficult to achieve as accurately as with a molded
plastic or a die cast card enclosure.  The reason is due to features
used for alignment (such as holes or slots) which are punched into
the sheet metal prior to forming.  This makes close tolerances for
these alignment features difficult to achieve.  Also, additional
hardware for alignment is required to be attached to either the card
enclosure or the board, such hardware including dowel or alignment
pins that are either press fit or attached with a fastener.
Perpendicularity of these pins is also a problem due to the
relatively small material thickness of the sheet metal.  This method
of board alignment has an accumulation of tolerances that would
impact the accurate alignment of the board to the card enclosure.

      To achieve a more accurate alignment method for the board to
the card enclosure, the three-point tab and slot method for sheet
metal card enclosures was developed. Accurate alignment is achieved
by locating the edges of three slots in the board to the edges of
three tabs 1, 2 and 3 bent out of the sheet metal card enclosure
(Fig. 1).  This three-tab arrangement is also illustrated in the
perspective vie...