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Method for a thin-film thermal sensor for accurate case temperature measurement

IP.com Disclosure Number: IPCOM000006378D
Publication Date: 2001-Dec-28
Document File: 5 page(s) / 142K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a thin-film thermal sensor for accurate case temperature measurement. Benefits include improved performance and improved reliability.

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Method for a thin-film thermal sensor for accurate case temperature measurement

Disclosed is a method for a thin-film thermal sensor for accurate case temperature measurement. Benefits include improved 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 is introduced in the case temperature measurement by using the conventional method of a thermocouple and adhesive/epoxy for its attachment.

              The conventional state of the art solution is to use a J-, K-, or T-type 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 thin-film thermoelement joint on the heat spreader. The key element of this method is a heat spreader with two electrical, insulted thin layers and one thin layer made of P and N types of thermoelements.

Advantages

              The technical advantages of the disclosed method include:

·        The location of the thin‐film thermal sensor can be placed on the heat spreader consistently.

·        A good physical contact is ensured between the thin‐film thermal sensor and the heat spreader. No extra thermal resistance is introduced by adhesive or epoxy.

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

·        The impact of thin‐film thermal sensor on the thermal interface thickness post heat sink assembly is minimal.

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

·        The thin‐film thermal sensors can be shipped with the thermal samples, customer samples, and even the...