Browse Prior Art Database

I/O Pin Retention Fixture

IP.com Disclosure Number: IPCOM000042546D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Knapp, DG: AUTHOR [+4]

Abstract

This articles describes a fixture for assuring retention of the I/O pins to the I/O pads on a multi-chip substrate during multiple reflow furnace cycling. This is achieved by utilizing a reflow hole matrix fitted over the I/O pins with each hole in the matrix aligned with one of the I/O pins. Each hole in the matrix is counterbored for receiving a steel ball which contacts one end of an I/O pin. A leaf spring matrix is fitted over and clamped onto the reflow hole matrix, thereby forcing each of the steel balls into contact with one of the I/O pins. The force exerted on the I/O pins by the steel balls in conjunction with the leaf spring matrix maintains the integrity of the I/O pin-pad connection during reflow furnace cycling. As shown in the figure, I/O pads 3 in substrate 1 are connected to I/O pins 2 at pad braze fillets 7.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 67% of the total text.

Page 1 of 2

I/O Pin Retention Fixture

This articles describes a fixture for assuring retention of the I/O pins to the I/O pads on a multi-chip substrate during multiple reflow furnace cycling. This is achieved by utilizing a reflow hole matrix fitted over the I/O pins with each hole in the matrix aligned with one of the I/O pins. Each hole in the matrix is counterbored for receiving a steel ball which contacts one end of an I/O pin. A leaf spring matrix is fitted over and clamped onto the reflow hole matrix, thereby forcing each of the steel balls into contact with one of the I/O pins. The force exerted on the I/O pins by the steel balls in conjunction with the leaf spring matrix maintains the integrity of the I/O pin-pad connection during reflow furnace cycling. As shown in the figure, I/O pads 3 in substrate 1 are connected to I/O pins 2 at pad braze fillets 7. Reflow furnace cycling at temperatures higher than that required to braze I/O pins 2 to I/O pads 3 can cause degradation of the I/O pin-pad fillets 7 and in some cases can even cause separation of I/O pins 2 from pads 3. Reflow hole matrix 4, which may be constructed out of graphite, has a plurality of holes 8, with each hole 8 fitting over one of the I/O pins 2 on substrate
1. Each hole 8 is counterbored at the end opposite the substrate 1 so as to receive a single stainless steel ball 5. Balls 5 are vibrated into holes 8, with the diameters of holes 8 and balls 5 being chosen so that only one ball will fit into a ...