An advanced multichip module (MCM) for high-performance UNIX servers

Abstract

In 2001, IBM delivered to the marketplace a high-performance UNIX ® -class eServer based on a four-chip multichip module (MCM) code named Regatta. This MCM supports four POWER4 chips, each with 170 million transistors, which utilize the IBM advanced copper back-end interconnect technology. Each chip is attached to the MCM through 7018 flip-chip solder connections. The MCM, fabricated using the IBM high-performance glass-ceramic technology, features 1.7 million internal copper vias and high-density topsurface contact pad arrays with 100-m pads on 200-m centers. Interconnections between chips on the MCM and interconnections to the board for power distribution and MCM-to-MCM communication are provided by 190 meters of co-sintered copper wiring. Additionally, the 5100 off-module connections on the bottom side of the MCM are fabricated at a 1-mm pitch and connected to the board through the use of a novel land grid array technology, thus enabling a compact 85-mm ؋ 85-mm module footprint that enables 8-to 32-way systems with processors operating at 1.1 GHz or 1.3 GHz. The MCM also incorporates advanced thermal solutions that enable 156 W of cooling per chip. This paper presents a detailed overview of the fabrication, assembly, testing, and reliability qualification of this advanced MCM technology.

Microjet Cooler with Distributed Returns

“…To interconnect the top and bottom sides of each macro-cell, both inlet and outlet ports interconnect to four inlet and four outlet microchannels to distribute the fluid sideways within the cell volume, and each microchannel is in turn connected to four jets or four return ports on the cooler bottom surface. The top section of the cooler (see Figure 7, The manufacturing process needed to build the designed cooler is based on a recent modification [7,8] of existing MLC manufacturing technology [9], which now enables us to build intricate microchannels and interlayer connecting vias inside a multilayer ceramic substrate. Table 2 outlines the conventional MLC build process, starting with Al 2 O 3 -MgO-SiO 2 glass particles mixed with organic binders and solvents to form glass ceramic greensheets on casting.…”

Efficient spreaders for cooling high-power computer chips

“…The analysis also assumes that the dissipation heat flux, q Chip , from the top surface of the chip (À0.5L Chip 6 x 6 0.5L Chip , À0.5L Chip 6 y 6 0.5 and z = 0) is uniform. However, in actuality the heat dissipation by the chips is non-uniform with a peak heat flux $2-3 times the average heat flux [1,2]. In addition, the analysis assumes that both the bottom surface and the sides of the chips are thermally insulated, or adiabatic.…”

“…The ever-increasing thermal power dissipation by chips of more than 100 W, at an average heat flux that is approaching or exceeding 50 W/cm 2 needs to be removed, while keeping the junctions or die temperatures below 85°C. The local heat flux at the hot spots on the surface of these chips could be as much as 100 W/cm 2 [1,2]. Enhanced heat dissipation from the computer chips is achieved using efficient spreaders cooled by saturation or subcooled nucleate boiling of dielectric liquids, such as FC-72 and HFE-7100.…”

Finite Element Analysis and Experiment Validation of Highly Reliable Silicon and Glass Interposers-to-Printed Wiring Board SMT Interconnections

“…However, they offer limited compliance if applied at the board level without underfill. Land grid array (LGA) packages have been employed to connect ceramic modules of same CTE as silicon to the system board [7]. Scaling to finer pitch is a potential challenge for LGA technology.…”