Background

Heat spreaders are crucial components that absorb heat from miniature semiconductor dies and spread it to larger areas to facilitate effective heat removal. Cooling relies on an efficient transfer of heat from the component or device. Important properties of any heat spreader material or structure are the thermal conductivity (TC) and coefficient of thermal expansion (CTE).

Due to the large CTE mismatch between the heat spreader material and the semiconductor die, a thick layer of thermal grease (TIM1) must be applied between the semiconductor and the heat spreader to absorb the shear caused by differential thermal expansion.

This TIM1 layer results in a significant additional thermal resistance and itself can suffer from long term reliability issues due to the operational cycles and CTE mismatching causing ‘pump-out’ of the grease

Technology Overview

This technology describes thermal structures on semiconductors that exhibit a combination of high TC and low CTE. Cold Spray (additive manufacturing) allows for the production of high performance heat spreaders with:

Tailored characteristics
Different materials or combination of materials such as composites or metal-composites

Further Details:

R.J. MacNamara, T.L. Lupton, R. Lupoi, A.J. Robinson, Enhanced Nucleate Pool Boiling on Copper-Diamond Textured Surfaces, Applied Thermal Engineering, 162, 2019, p114145 Journal Article, 2019 DOI
Lupoi, T. Lupton, R. Jenkins, A.J. Robinson, G.E. O’Donnell, Direct manufacturing of diamond composite coatings onto silicon wafers and heat transfer performance, Journal Article, 2018 DOI

Stage of Development

Cu-Diamond matrix technology demonstrators have been fabricated with TC~600W/(mK).

Benefits

Copper-diamond matrixes formed by cold spraying are highly thermally conductive and have a low CTE, making them extremely suitable for thermal applications such as in heat spreaders.
Very low (potentially zero) thermal resistance at the interface between materials - and that has a 2D boiling surface on the uttermost layer.
Removes the need for TIM1. Can be deposited directly on substrate.
All of the above, in one single processing step

Applications

Electronics, cooling, consumer electronics, data centre cooling.

Opportunity

Available to licence
Research collaboration

Novel Copper-Diamond Composite Heat Spreaders using Cold Spray

Patents

IP Status

Seeking