Integrated circuit temperature sensing device and method

An integrated circuit (IC) temperature sensing device includes a temperature sensor positioned within a conductive temperature sensor housing and a thermal insulator surrounding the conductive temperature sensor housing. The sensor housing and thermal insulator are positioned within an IC temperature control block that heats or cools the IC. The temperature sensor housing comes into thermal contact with an IC undergoing burning-in, testing or programming. The temperature sensor housing provides a short thermal path between the IC under test and the temperature sensor. The thermal insulator thermally isolates the temperature sensor from the temperature control block so that the temperature sensor predominantly measures the temperature of the IC. The method of sensing the temperature of an IC includes actively changing the temperature of an IC with a heater or cooler, sensing the temperature of the IC with a temperature sensor positioned within a conductive sensor housing in thermal contact with the IC and thermally insulating the sensor housing and temperature sensor from the heater or cooler.

FIELD OF THE INVENTION

This invention relates to integrated circuit testing sockets and more particularly to the sensing of the temperature of an integrated circuits in an integrated circuit testing socket.

BACKGROUND OF THE INVENTION

Integrated circuit (IC) packages must be tested after their manufacture, normally at elevated temperatures, which is typically a burn-in process. During that process, it is often necessary to control the temperature of ICs, sensors, and other elements. Techniques for doing so have been widely practiced for many years. The system normally includes a heater (or cooler) and a temperature sensor. Temperature control modules and temperature sensors of many types are widely sold for these purposes. A typical application is the control of the temperature of ICs for a burn-in process because of the temperature sensitivity of the ICs.

Two such examples of heating and sensing ICs in a socket can be found in U.S. Pat. No. 5,164,661 to Jones and U.S. Pat. No. 5,911,897 to Hamilton. As shown in FIG. 1, in Hamilton, a temperature sensor 10 is positioned within an insulated sensor housing 12 such that the sensor 10 protrudes from the housing 12 to contact the integrated circuit being tested. The sensor housing 12 is located in an opening in the heat sink 14.

In both Hamilton and Jones, the temperature sensor directly contacts the integrated circuit when the socket is closed. The direct contact between the temperature sensor can cause damage to the integrated circuit because of the point loading of the relatively small temperature sensor on the integrated circuit when the socket is clamped closed. Damage to the temperature sensor can also be caused by the direct contact of the integrated circuit to the sensor.

Thus, it would be advantageous to have a temperature measuring arrangement that could accurately measure the temperature of an integrated circuit during active thermal control of the integrated circuit while providing a way to protect both the integrated circuit and the temperature measuring device from damage caused intimate contact of the two.

DETAILED DESCRIPTION

FIG. 2shows an integrated circuit temperature sensing device20according to the invention in an integrated circuit testing socket23. Integrated circuits include individual dies and IC packages and the term integrated circuit (IC) used throughout this specification encompasses all forms of integrated circuits. The testing socket23can be a socket designed to receive an IC26for testing which includes, burning-in, testing and programming of the IC26.

The IC testing socket23includes temperature control block24for directly controlling the temperature of the IC during testing. The IC testing socket23generally comprises a base40connected to a testing board42and a lid44. The preferred form of IC testing socket is described in further detail in U.S. Provisional Application No. 60/548,303. However, particulars of construction of the IC testing socket are not necessary to the present invention and so need not be described further herein. For example, the present invention can be incorporated into other IC testing sockets such as described in U.S. Pat. No. 5,911,897 to Hamilton and shown inFIG. 1.

The temperature control block24is positioned in the lid44so that when the IC testing socket23is in a closed position, the temperature control block24thermally contacts the IC26. The temperature control block24then effects a change in the temperature of the IC26by conducting heat to or from the IC26. Thus, the temperature control block24can be a heater or a cooler.

The IC temperature sensing device20is shown located within the temperature control block24positioned so as to thermally contact the IC26when the IC testing socket is in a closed position.

FIG. 3shows a partial cross-sectional view of the IC testing socket23ofFIG. 2showing the IC temperature sensing device20positioned within the temperature control block24.FIG. 4shows an exploded perspective view of the temperature sensing device20.

Referring toFIGS. 3 and 4, the IC temperature sensing device includes a temperature sensor30, such as a thermistor, in electrical communication with devices capable of converting the temperature sensor signals into useable form. One such device can be a microprocessor controller that acts as a controller, responding to the temperature sensor30and driving the temperature control block24.

The temperature sensor30is positioned within a cavity32of the thermally conductive sensor housing34. The cavity32is shown here as being cylindrical, reflecting the overall shape of the temperature sensing device20. The cavity32has a single opening at a first end of the sensor housing34to allow the temperature sensor to be in communication with devices like a microprocessor controller or off-board controller. When the IC testing socket23is in a closed position, the sensor housing34is in thermal contact with the IC26. Because the sensor housing34is thermally conductive, the sensor housing34is able to provide a thermally conductive path between the IC26and the temperature sensor30.

The cavity32is formed as a blind bore which includes an open first end and a conically shaped termination36at a second end of the sensor housing34. The conically shaped termination36has a thickness which allows for a short thermal path for a fast transient response from the IC26to the temperature sensor30. A suitable thickness for producing the short thermal path is 3 mm when the sensor housing34is formed of a metal comprising copper or aluminum.

A thermal insulator38surrounds the sensor housing34to thermally isolate the temperature sensor30from the temperature control block24. The second end of the sensor housing34is exposed from the thermal insulator38to allow the sensor housing34to thermally contact the IC26when the IC testing socket23is in a closed position.

The sensor housing34provides both a thermally conductive path from the IC26to the temperature sensor30and protection from impact or problems related to point contact pressures that could occur if the IC26directly, physically contacted the temperature sensor30. The sensor housing34protects the temperature sensor30by providing a protective layer of material that intervenes between the IC26and the temperature sensor30. The sensor housing34protects the IC26from point contact pressures that could be cause by directly contacting a temperature sensor30by providing a larger, substantially flatter contact surface area than the small temperature sensor30can provide.

For the most accurate results in sensing the temperature of an IC26during testing, the sensor housing34should be formed a highly conductive metal. Most preferably, the sensor housing34is formed of a metal comprising aluminum or copper. Also, to increase accuracy, the thermal insulator38should adequately thermally isolate the temperature sensor30and sensor housing34from the temperature control block24so that the temperature sensor30is predominantly sensing the temperature of the IC26and not the temperature control block24. To achieve thermal isolation, the thermal insulator38is most preferably formed of a polythermide material. Ultem 1000®, manufactured by General Electric, is an example of a preferable polythermide material.

Method of Sensing an IC Temperature During Testing of the IC

A method for sensing the temperature of an IC26being tested includes placing the IC26in an IC testing socket23. The temperature of the integrated circuit is changed by thermally contacting a heater or cooler24to the integrated circuit. This is chiefly done in the burning-in process for ICs but the temperature of the IC26can also be controlled for programming and testing of the IC26.

The temperature of the IC26is then sensed by means of a temperature sensor device20contained within the heater or cooler24. The temperature sensor device20senses the temperature of the IC26by thermally connecting a temperature sensor30to the IC26through a conductive material34and by thermally isolating the temperature sensor30from the heater or cooler24with a surrounding insulating material38so that the temperature sensor30predominantly sense the temperature of the IC26and not the heater or cooler24.

The conductive material34spaces the temperature sensor30from the IC26such that a thermal path between the IC26and temperature sensor30is maintained to create a fast transient response in the temperature sensor30.

The temperature sensor30is thermally isolated from the heater or cooler24by positioning the temperature sensor30within a thermally conductive sensor housing30that is surrounded by thermally insulating material38such that first and second ends of the sensor housing34are exposed. The sensor housing34and thermally insulating material38are then positioned within an appropriately sized and shaped opening in the heater or cooler24so that the thermally conductive housing34can be in thermal contact with the IC26.

Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention can be modified in arrangement and detail without departing from such principles. I claim all modifications and variation coming within the spirit and scope of the following claims.