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Method for an embedded thermal sensor for accurate case temperature measurement on a copper heat spreader

IP.com Disclosure Number: IPCOM000006379D
Publication Date: 2001-Dec-28
Document File: 5 page(s) / 1K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an embedded thermal sensor for accurate case temperature measurement on a copper heat spreader. Benefits include improved thermal performance and improved reliability.

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Method for an embedded thermal sensor for accurate case temperature measurement on a copper heat spreader

Disclosed is a method for an embedded thermal sensor for accurate case temperature measurement on a copper heat spreader. Benefits include improved thermal performance and improved reliability.

Background

              Thermal characterization of electronic packages requires accurate measurement of case temperature so that the junction‐to‐case and case‐to‐ambient thermal resistance can be accurately calculated. A significant error of case temperature measurement is introduced by using the existing method of a thermocouple and adhesive/epoxy for its attachment.

              The conventional solution is to use a J-, K-, or T-type of thermocouple to measure the case temperature, as shown in Figure 1. The thermocouple beads are attached to the heat spreader surface by adhesive or epoxy. However, a bias of case temperature measurement can be introduced by several factors, including:

·        Misplacement of thermocouple bead location with respect to the heat spreader

·        Poor physical contact between the thermocouple bead and the heat spreader

·        Extra thermal resistance resulting from the adhesive/epoxy that gets in between the thermocouple bead and the heat spreader

General description

              The disclosed method utilizes a metal plating process to form a T‐type thermocouple joint on the Cu heat spreader. The key element of the method is a copper heat spreader with two electrical, insulated thin layers and one Cu‐Ni alloy (55% Cu and 45% Ni) thin layer.

Advantages

The technical advantage of the disclosed method include:

·        The location of the embedded thermal sensor can be placed on the heat spreader consistently.

·        A good physical contact is ensured on the embedded thermal sensor joint. No extra thermal resistance is introduced by adhesive or epoxy.

·        No hole or groove is required on the heatsink near the location of the case temperature measurement to route the thermocouple wires out.

·        The impact of the embedded thermal sensor on the thermal interface thickness post heatsink assembly is minimal.

·        The fall‐off of adhesive/epoxy for thermocouple attachment post reliability tests can be avoided.

·        The embedded thermal sensor can be shipped with the thermal samples, customer samples, and even the f...