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Self-cooling 2.5D power module with ultra-small footprint

IP.com Disclosure Number: IPCOM000248119D
Publication Date: 2016-Oct-27
Document File: 8 page(s) / 450K

Publishing Venue

The IP.com Prior Art Database

Abstract

With advancing technology, the size of power-supply components on server

motherboards is continually shrinking. This trend in shrinking size and corresponding increase in

density of power-supply components mirrors the trend in computing elements. However, power- conversion efficiency remains the same even as density of power-supply components increases.

Due to the unchanged power-conversion efficiency, a larger amount of heat is generated in a

smaller volume and heat dissipation requirements become greater. Heat sinks are added to

dissipate heat, and these may need more space than the space freed up by shrinking the power

components. This disclosure describes self-cooling power modules constructed with 2.5D

packaging technology that obviate the need for heat sinks, enabling higher density and lower

cost. Use of 2.5D packaging technology enables a very small footprint for the power module,

thereby improving availability of motherboard area for laying out computing components,

routing components, etc.

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Page 01 of 8

Self-cooling 2.5D power module with ultra-small footprint

    With advancing technology, the size of power-supply components on server motherboards is continually shrinking. This trend in shrinking size and corresponding increase in density of power-supply components mirrors the trend in computing elements. However, power- conversion efficiency remains the same even as density of power-supply components increases. Due to the unchanged power-conversion efficiency, a larger amount of heat is generated in a smaller volume and heat dissipation requirements become greater. Heat sinks are added to dissipate heat, and these may need more space than the space freed up by shrinking the power components. This disclosure describes self-cooling power modules constructed with 2.5D packaging technology that obviate the need for heat sinks, enabling higher density and lower cost. Use of 2.5D packaging technology enables a very small footprint for the power module, thereby improving availability of motherboard area for laying out computing components, routing components, etc.

KEYWORDS

● Power distribution network ● Power module
● Self-cooling
● Heat sink
● PCB footprint

ABSTRACT


Page 02 of 8

BACKGROUND

Fig. 1: Schematic of a power supply at a data center

    Fig. 1 shows a schematic of an example high-density power supply for a compute server. A first stage buck-boost converter (102) accepts an input voltage Vin from, e.g., a server rack, and generates an output voltage Vibc , which is, e.g., an intermediate bus converter voltage. For example, one value of Vin is 54V, and a corresponding value of Vibc is 48 V. The first stage is based on, for example, a pre-regulated zero-voltage switching technology. The second stage (104) steps down Vibc to a voltage level Vdd that is suitable for a CPU (106). An example value for Vdd is 1.8 V. The second stage is, for example, an unregulated inductor-inductor-capacitor (LLC) converter with a 30:1 step-down ratio. Further voltage regulation is performed by an integrated voltage regulator (IVR) situated on-board the CPU module. The IVR regulates Vdd to the die voltage Vdie. The power efficiency of the three-stage system of Fig. 1 is typically 85%. The first two stages of Fig. 1 together have a footprint of about 45mm by 45 mm.


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Fig. 2: Power supply and CPU modules on a motherboard

    Fig. 2 shows the power supply and CPU modules as arranged on a motherboard. Fig. 2(a) is the side view, and Fig. 2(b) is the front view. Two power modules (102, 104) supply power to a CPU (106). Power and CPU modules are both placed on a motherboard (202). Although the two power modules together occupy only a relatively modest area of 45×45 mm2, the heat sink (204) for the power modules occupies a much larger area 80×60 mm2, and is 30 mm tall. The modest area footprint and high density of the power modules is thus more than offset by the large volume of heat sink. Besides the large volume of the heat sink, the long side p...