Browse Prior Art Database

Conversion of Metal Lid Module to EMI Container

IP.com Disclosure Number: IPCOM000112579D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Bui, D: AUTHOR [+4]

Abstract

This invention describes two methods to achieve a reduction in Electromagnetic Interference (EMI). First, the lid on the module can be extended, as seen in Fig. 2. The metal of the lid is then mated to the metal of the ground plane (Fig. 1), and if the connecting fingers are 200 mills or less, the direct radiation will drop by 25 dB i the 1 to 5 GHz range. The second way (Fig. 3) is to add fingerstock on the planar. This fingerstock will make contact every 200 mils between the metal of the lid and the copper of the ground plane. In both cases, the EMI is contained in this shielded box package formed by connecting the ground plane to the metal lid of the module.

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Conversion of Metal Lid Module to EMI Container

      This invention describes two methods to achieve a reduction in
Electromagnetic Interference (EMI).  First, the lid on the module can
be extended, as seen in Fig. 2.  The metal of the lid is then mated
to the metal of the ground plane (Fig. 1), and if the connecting
fingers are 200 mills or less, the direct radiation will drop by 25
dB i the 1 to 5 GHz range.  The second way (Fig. 3) is to add
fingerstock on the planar.  This fingerstock will make contact every
200 mils between the metal of the lid and the copper of the ground
plane.  In both cases, the EMI is contained in this shielded box
package formed by connecting the ground plane to the metal lid of the
module.

      This new feature is utilizing existing metal cover form factor
on a module to extend the EMI performance by a factor of 10 X.  Also,
if the metal cover is made of copper, it must be soldered directly to
the ground plane, giving better thermal conductivity chip to air
(which would extend the power capacity of the module) as well as
improving the EMI performance.  The advantage of this over trying to
contain the noise at the box level is the cost advantage of
containing the noise at the source instead of at the multiple (and
large) seams of the box.