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Method for a high performance, thin film TEC with minimal contact resistance

IP.com Disclosure Number: IPCOM000032215D
Publication Date: 2004-Oct-26
Document File: 5 page(s) / 88K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a high performance, thin film thermoelectric cooler (TFTEC) with minimal contact resistances (Rc). Benefits include improved functionality and improved performance.

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Method for a high performance, thin film TEC with minimal contact resistance

Disclosed is a method for a high performance, thin film thermoelectric cooler (TFTEC) with minimal contact resistances (Rc). Benefits include improved functionality and improved performance.

Background

      Electrical connection with minimal contact resistance is required for a thermoelectric cooler. Additionally, a die with a TEC is required to be attached to an integrated heat spreader (IHS) with high performance thermal interface material (TIM). However, no conventional solutions exist for these requirements.

      As Rc increases, achieving junction temperature (Tj) reduction becomes extremely difficult. An Rc of 1.3e-7 ohm-cm2 or lower leads to good performance of the TEC (see Figure 1).

      A conventional die-IHS stack includes several items, including (see Figure 2):

•             Package

•             Controlled collapse chip collect (C4) solder balls

•             Die

•             Electrical contact

•             Thin film thermoelectric cooler (TFTEC) legs

•             Insulator

•             Heat spreader

              The use of a nonflat heat spreader conventionally leads to poor thermal dissipation (see Figure 3).

 

General description

      The disclosed method is a high performance, thin film thermoelectric cooler with minimal contact resistance. The method attaches a die with a thin-film TEC onto a heat sink with minimal performance degradation.

              The key elements of the method include:

•             Attachment of a TEC to the back of a silicon die over a hot spot with metallic bonding

•             Integration of a die with thin thermoelements onto a heat spreader, such as a copper plate, using TIM and solder attachment with low thermal contact resistance

•             Accommodation of height differences due to surface nonplanarities in the IHS with a compliant material to create uniform, successful thermal contact

             

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to providing a big junction temperature (Tj) reduction

•             Improved functionality due to dissipating heat from the hot side of the TEC

•             Improved performance due to providing a strong electrical contact between the TFTEC and the IHS

Detailed description

      The disclosed method attaches a die with a thin film TEC onto a heat spreader. Integration of die with thin thermoelements onto a heat spreader, such as a copper plate, using a thin, complaint TIM is required for efficient heat transfer from the TEC to the heat spreader. Because the heat spreader may not be uniform in height, the height differences must be accommodated to enable successful thermal contact (see Figure 4).

      The disclosed method can be implemented using the following steps:

1.   Deposit thin thermal interface materials such as pure indium, pure Sn, SnAg or other relatively higher thermal...