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Method for thermal enhancement of low-profile packages by utilizing EMI metal shielding or a metal heat spreader

IP.com Disclosure Number: IPCOM000009965D
Publication Date: 2002-Oct-02
Document File: 4 page(s) / 269K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for thermal enhancement of low-profile packages by utilizing electromagnetic interference (EMI) metal shielding or a metal heat spreader. Benefits include improved thermal performance.

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Method for thermal enhancement of low-profile packages by utilizing EMI metal shielding or a metal heat spreader

Disclosed is a method for thermal enhancement of low-profile packages by utilizing electromagnetic interference (EMI) metal shielding or a metal heat spreader. Benefits include improved thermal performance.

Background

        � � � � � � Conventional metal caps are used for EMI shielding but are not fully utilized for thermal management.

� � � � � The power dissipation of electronic packages keeps increasing. For mobile, handheld, and cellular phone environments, thermal management of the hot components is not sufficient using natural convection.

� � � � � CPU products are easily cooled using an integrated heatsink. Non-CPU products are more difficult to cool due to the space and airflow constraints that make a heatsink solution impractical. This problem is conventionally solved by increasing the metal layers inside the printed circuit board (PCB) or by adding a thermal vias to the package substrate and the PCB underneath the die area.

� � � � � A cross-sectional view and picture (see Figure 1) of the conventional method shows a package with an overall height of around 1-1.3 mm. The gap between the component and the metal cap is about 0.3 mm. The metal cap is made of copper with a thickness of about 0.16 mm.

General description

        � � � � � The disclosed method is to utilize the EMI metal cap or a metal heat spreader to conduct heat from the component’s top surface to the PCB. A thermally conductive but electrically isolated material can be inserted between the hot component and the EMI metal cap. Alternatively, a metal heat spreader may be directly coupled to the PCB. Either way, the heat transfer path from the component’s top surface to the PCB and the heat transfer path through solder balls result in a lower component temperature.

        � � � � � The key elements of the method include:

� •        � � � EMI metal cap and thermally conductive but electrically isolated material

•        � � � � Metal heat spreader that is attached to the top surface of the package by epoxy or molding process and then soldered directly to the PCB

� � � � � A thermal model simulation indicates that the overall thermal resistance can be reduced 20-30% by using the disclosed method, depending on the actual die size and the package height. Additional thermal benefit results for the cases with a larger die or lower package height because the heat ...