Thermal bond verification

Abstract

A system and method for evaluating the thermal bond between a heat-producing device and a heat-absorbing apparatus. The heat-producing device may be a CPU, such as an INTEL PENTIUM microprocessor, and the heat-absorbing apparatus may be a heat sink. The two may be joined with a heat-conducting substance such as thermal grease or adhesive. In one exemplary embodiment, the heat-producing device is operated at a first power level, a first temperature measurement is then taken, the device is operated at a second power level, and then a second temperature measurement is then taken. The thermal resistance is then calculated, which may involve subtracting the second temperature from the first, and may involve dividing by the power level. The first power level may be full power, and the second power level may be near zero. The first temperature may be measured when equilibrium temperatures have been reached, and the second temperature may be measured a predetermined amount of time after the second power level is initiated, which may be just enough time for the temperatures of the CPU and the heat sink to equalize. The CPU may perform the calculations, and the temperature may be measured with an on-board thermal sensor which may be a thermal diode.

Description

[0001] 1. Field of the Invention[0002] This invention relates generally to systems and methods for evaluating thermal bonds.[0003] 2. Description of the Related Art[0004] Many mechanical and electrical devices generate heat internally which must be dissipated to the environment to keep the devices within a range of desired operating temperatures. Such heat-producing devices may include engines, bearings, motors, power supplies, transformers, amplifiers, control modules, and computer chips and components including graphics controllers, network interfaces, and central processing units (CPUs). In some applications it is desirable to transfer heat from a heat-producing device to a heat-absorbing apparatus so that the heat may be used for useful purposes. These useful purposes may include generating electricity, providing heat for industrial processes, heating water, heating air (e.g. to heat the occupied space in buildings), or preventing freezing. Heat-absorbing apparatuses may compris...

AI Technical Summary

Problems solved by technology

A heat-conducting substance is typically a non-Newtonian fluid that may be tacky and flexible, at least when installed, so that it fills most of the microscopic gaps between the surfaces of the heat-producing device and heat-absorbing apparatus.

However, as with any manufacturing process, it is difficult or expensive to verify that all items manufactured have a good thermal bond.

There is typically a relatively small area on the top of the chip that may need to have a low resistance path to the heat sink and modifications to this area (e.g. drilling to insert a temperature probe) may dramatically affect its operation.

Due to the mechanical arrangement of the two parts (CPU and heat sink) as well as the complexities encountered when trying to remove heat from CPUs in confined spaces, in the past it has been difficult to verify during manufacture that the thermal bond between the CPU and the heat sink has been correctly made.

The calculating procedure may be performed by the device, and may involve dividing by the power consumption of the device.

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