Browse Prior Art Database

Board-To-Board Interconnects in a Thermal Conduction Module System

IP.com Disclosure Number: IPCOM000036054D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 4 page(s) / 138K

Publishing Venue

IBM

Related People

Donner, EO: AUTHOR [+2]

Abstract

Large computer systems using Thermal Conduction Module (TCM) packaging and cooling systems will continue to put more and more functions on individual boards. This will result in more and more interconnection and communication pathways. In some cases, it may be desirable to have one machine element communicate with another in one clock cycle or less. A solution to this problem is to provide for a direct boardto-board connection system for at least some channels. (Image Omitted)

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Board-To-Board Interconnects in a Thermal Conduction Module System

Large computer systems using Thermal Conduction Module (TCM) packaging and cooling systems will continue to put more and more functions on individual boards. This will result in more and more interconnection and communication pathways. In some cases, it may be desirable to have one machine element communicate with another in one clock cycle or less. A solution to this problem is to provide for a direct boardto-board connection system for at least some channels.

(Image Omitted)

An evolutionary approach to packaging these large modules is to mount 4 to 6 TCMs on a large multilayer organic board. To achieve high performance in an advanced processor configuration will require communications between multiple boards. An objective will be to connect these boards with a path sufficiently short to achieve a single machine cycle time interval between module units.

The current state-of-the-art board-to-board signal path communicates through a connection to the board wiring planes and then to an I/O connector which attaches high speed cable between the boards. The

(Image Omitted)

time of flight through high speed cable is approximately 50 to 60% per unit length of the board wire. To traverse relatively long distances, an effort must be made to eliminate using the slower wire of the board and communicate via the cable in as close proximity as possible to the module I/O pins.

A new TCM board would distribute both power and signals to the TCM. Therefore, the package that allows the TCMs to be packaged in closest proximity for this system configuration appears to be TCM boards (back-to-back) with interconnect wires on the back of each board directly under the TCM module.

The following package proposal illustrates several methods of achieving minimal paths between processor modules. The boards are arranged in close proximity to one another back-to-back in the systems frame illustrated in Fig. 1.

One of the methods for communicating between boards is to utilize a cable (high speed) connection from module pin/board 1 back surface to module pin/board 2 back surface, as illustrated in Fig. 1. To minimize the signal path in the slower printed circuit wire, an I/O pin connector-to-cable interface is connected directly behind the module to the board. Board surface wire is used to translate the via holes to printed circuit lands which connect to the I/O pin-to- cable connector. The cross-sectional view in Fig. 2 of the I/O pin connector is shown as a molding which groups many pins into strips.

Another approach to consider when connecting TCM boards back-to-back requires an additional board part number. This approach assumes that each board is wired as a mirror image of the other but is functionally equivalent. The A side board is wired so that the equivalent function TCM is directly in back of the

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TCM on the B side board. The A side and B side have identical wiring requiremen...