TECHNICAL FIELD

The present disclosure relates to thermal management of heat-generating electronic components, such as computer chips in electronic devices.

BACKGROUND

Electronic devices contain heat-generating electronic components such as computer chips mounted on circuit boards. These computer chips may require cooling to avoid reduced performance and damage caused by overheating. For example, where a computer chip is near its maximum operating limit, its MTBF (Mean Time Before Failure) is reduced by 50 percent for every 10° C. increase in temperature, according to “Military Handbook, Reliability Prediction of Electronic Equipment”, MIL-HDBK-2178B. Therefore, relatively moderate temperature increases can significantly reduce chip life.

A heat sink can be used to absorb and dissipate heat generated by a computer chip and/or other heat-generating electronic component in an electronic device. The heat sink can sometimes be integrated with the case or housing of the electronic device, or it may comprise a separate element such as a heat spreader which is enclosed within the case or housing. Regardless of its specific form, the heat sink is typically made from metal, having a mass and/or area significantly greater than that of the heat-generating electronic component in order to dissipate the heat. The heat sinks may include fins or other heat-dissipating elements.

Because heat sinks are comprised of metal, they must be electrically insulated from the heat-generating electronic component. Electrical insulation is typically achieved by providing a layer of dielectric, thermally conductive material between the heat-generating electronic component and the heat sink. Such materials are commonly known as “TIM” (Thermal Interface Material). The TIM layer is applied at the interface between an outer surface of the heat-generating electronic component and a surface of an immediately adjacent heat sink or heat spreader.

In addition to its role as a dielectric material, the TIM layer can enhance thermal conduction between the heat-generating electronic component and the heat sink, by filling gaps between the electronic component and the heat sink, in order to compensate for manufacturing tolerances of the components and the electronic device. The TIM layer may also provide protection from shocks and vibrations.

Because it must possess dielectric properties, the TIM layer may have relatively poor thermal properties, at least compared with the heat sink, leading to higher temperatures of the heat-generating electronic component. In addition to having poor thermal conductivity, the application of excessively thick TIM layers to compensate for manufacturing tolerances can further impair heat conduction from the heat-generating electronic component to the adjacent heat sink.

While efforts have been made to improve thermal properties of TIMs, and to reduce the thickness of TIM layers, there remains a need to improve conduction of heat between a heat-generating electronic components and a heat sink in an electronic device.

SUMMARY

In accordance with an aspect of the present disclosure, there is provided an electronic device, comprising: (a) a heat-generating component having a first surface and an opposite second surface; (b) a heat spreader having a first surface and an opposite second surface, wherein the heat spreader has an area which is at least about 4 times greater than an area of the heat generating component, wherein the first surface of the heat spreader is in thermal contact with the first surface of the heat-generating component along a first interface, and wherein the first interface is non-dielectric and defines a first interface area; (c) a heat sink having a first surface and an opposite second surface, wherein the heat sink has a greater mass than the heat spreader and comprises one or more layers of thermally conductive metal or non-metal between the first and second surfaces of the heat sink, wherein the first surface of the heat sink is in thermal contact with the second surface of the heat spreader along a second interface, wherein the second interface defines a second interface area which is greater than the first interface area; and (d) a layer of a dielectric TIM (thermal interface material) provided at the second interface and in direct contact with the second surface of the heat spreader and the first surface of the heat sink, wherein the second interface is dielectric.

According to an aspect, the heat sink has a greater area than the heat spreader, and a greater thickness, mass and area than the heat-generating component.

According to an aspect, the heat-generating component is a heat-generating electronic component, wherein the second surface of the heat-generating component faces toward a circuit board on which the heat-generating component is mounted.

According to an aspect, the first surface of the heat-generating component is flat, and wherein the area of the heat-generating component is substantially the same as the first interface area.

According to an aspect, the area of the heat spreader is about 5-100 times greater than the area of the heat-generating component.

According to an aspect, the first surface of the heat-generating component is in direct contact with the first surface of the heat spreader along said first interface, without any TIM being provided at the first interface.

According to an aspect, a layer of at material with high thermal conductivity and low dielectric strength is provided at the first interface.

According to an aspect, the layer of TIM at the second interface has a thickness from about 0.1 mm to about 0.5 mm.

According to an aspect, the heat spreader comprises a sheet or plate comprising one or more layers of thermally conductive metal or non-metal.

According to an aspect, the thermally conductive metal is aluminum or copper, and the thermally conductive non-metal is graphite.

According to an aspect, the heat spreader comprises a vapor chamber or a heat pipe.

According to an aspect, the heat spreader has a thickness of about 50-2,000 micrometers.

According to an aspect, the heat sink comprises at least a portion of a housing of the electronic device.

According to an aspect, the second surface of the heat sink comprises an external surface of the electronic device.

According to an aspect, the second surface of the heat sink is provided with a plurality of cooling fins.

According to an aspect, the first and second interfaces are spaced apart along an axis which is parallel to the first interface.

According to an aspect, the heat spreader comprises a first portion on which the first interface is defined, a second portion on which the second interface is defined, and a connecting portion which extends between and connects the first and second portions, wherein the second portion has an area which is greater than an area of the first portion.

According to an aspect, the first and second portions of the heat spreader are offset relative to one another along an axis which is perpendicular to the first interface, such that they are located in different planes.

According to an aspect, the electronic device further comprises a resilient member which exerts a compressive force to the heat-generating component and the first portion of the heat spreader at the first interface, wherein the compressive force is directed along an axis which is perpendicular to the first interface.

According to an aspect, the resilient member comprises a layer of a resilient dielectric material which is provided between, and in compressive contact with, the second surface of the heat spreader in the first portion thereof, and an adjacent surface of the electronic device.

