Browse Prior Art Database

Method for air venting a cellular phone without EMI leakage

IP.com Disclosure Number: IPCOM000008597D
Publication Date: 2002-Jun-25
Document File: 4 page(s) / 46K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for air venting a cellular phone without EMI leakage. Benefits include improved thermal performance and improved reliability.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 50% of the total text.

Method for air venting a cellular phone without EMI leakage

Disclosed is a method for air venting a cellular phone without EMI leakage. Benefits include improved thermal performance and improved reliability.

Background

              The power dissipation of the components inside the cellular phone keeps increasing. For the conventional cellular phone design, the major heat from the logic component is dissipated through the keypad to the external ambient air. Because the keypad is typically made of silicone rubber with low thermal conductivity, the heat transfer is not efficient, especially for high performance logic components. Heat dissipation to external ambient air is difficult if the hot components are located in the middle of the phone and surrounded by the PCB and battery (see Figure 1).

              The conventional solution is to reduce the power dissipation of each component as much as possible. Alternatively, the hot components were placed far away from each other so that the power dissipation does not concentrate in a small PCB location.

General description

              The disclosed method, called a cooling tunnel, is an air-duct design that conveys cool air through the hot components without EMI leakage. The cooling tunnel is made of Cu or other metals. The inlet of the tunnel is located on the bottom of the cellular phone, while the outlet is located on the front panel. The heat from the hot components is dissipated to the air inside the tunnel through the thermal conductive elastomer. The air inside the tunnel is moved by natural convection. Both ends of the cooling tunnel are grounded to the EMI shield to form a completely sealed enclosure so that EMI does not leak through the cooling tunnel.

      Note: EMI leakage remains an issue because of open venting holes on the cellular phone case.

      The key elements of the method include:

·        Venting duct design made of Cu or other metals

·        Thermal conductive elastomer that conducts heat from the hot components to the duct wall

·        EMI gasket or solder to ground the metal duct to the EMI shield inside the cellular phone

 


Advantages

              The disclosed method provid...