Electromagnetic interference (EMI) shield and fastener apparatus and method

An apparatus and method for shielding electromagnetic interference (EMI) and fastening housing members includes a clip for fastening to a first housing member including a length. The clip includes a plurality of longitudinally oriented openings formed therein and a plurality of dimples formed therein spaced along the length of the clip for engaging with a second housing member.

FIELD OF THE INVENTION 
This invention relates generally to the field of electromagnetic 
interference (EMI) shields, and in particular, to an EMI shield which 
mechanically fastens two housing members together to reduce EMI emissions 
by preventing unacceptable levels of electromagnetic radiation from 
exiting the housing of an electronic device. 
BACKGROUND OF THE INVENTION 
Most electronic devices have a rigid housing to protect the internal 
electronic components and to prevent electromagnetic radiation generated 
by the components from exiting the housing. Excessive electromagnetic 
interference (EMI) is a widespread problem in many electronic devices, 
especially in the high speed network systems products. These electronic 
devices must meet very stringent emissions standards in the United States 
and in other foreign countries. 
The housing for these types of electronic devices typically includes a top 
housing member and a bottom housing member which are mechanically fastened 
together by a plurality of screws. The screws are typically spaced several 
inches apart along the outer edge of the housing. There are certain 
disadvantages to this arrangement. First, screws which are placed several 
inches apart along the edge of the housing do not provide a continuous 
seal between the top housing member and the bottom housing member. This 
arrangement may allow unacceptable levels of electromagnetic radiation to 
exit the housing thereby creating excessive EMI. Second, there are high 
costs associated with the manufacture and assembly of electronic devices 
that utilize mechanical fasteners such as screws. In particular, several 
threaded screw holes must be formed around the perimeter of the housing 
during the manufacturing process. Moreover, each screw must be manually 
installed by an assembly worker which substantially increases the time 
required to assemble the device. 
Accordingly, it would be desirable to have an EMI shield and fastener 
apparatus that overcomes the disadvantages described above, and to provide 
a simple and cost effective EMI shield and fastener apparatus. 
SUMMARY OF THE INVENTION 
One aspect of the invention provides an electromagnetic interference (EMI) 
shield and fastener apparatus. A clip for fastening to a first housing 
member includes a length. The clip includes a plurality of longitudinally 
oriented openings formed therein and a plurality of dimples formed therein 
spaced along the length of the clip for engaging with a second housing 
member. The dimples may have a curved contact surface. The longitudinally 
oriented openings may be rectangular in shape. The clip may have a 
rectangular shape and may be formed from a single piece of conductive 
material. The conductive material may be steel. The clip may be welded to 
the first housing member. 
Another aspect of the invention provides an electromagnetic interference 
(EMI) shield and fastener apparatus. A clip includes a first longitudinal 
portion and a second longitudinal portion, the first longitudinal portion 
for fastening to a first housing member. A plurality of step portions are 
spaced along and between the first and second longitudinal portions. A 
plurality of dimples are spaced along the second longitudinal portion for 
contacting with a second housing member. The step portions may be oriented 
substantially perpendicular to the first and second longitudinal portions. 
The dimples may be equally spaced apart along the second longitudinal 
portion and between the step portions. 
Another aspect of the invention provides an electromagnetic interference 
(EMI) shield and fastener apparatus. A top housing member and a bottom 
housing member is provided. The top housing member includes a top side 
including an inner surface. The bottom housing member includes a flange 
portion. A clip includes a first longitudinal portion and a second 
longitudinal portion. The first longitudinal portion is fastened to the 
inner surface of the top side of the top housing member. The second 
longitudinal portion includes a plurality dimples formed therein. A 
plurality of step portions spaced along and between the first and second 
longitudinal portions is provided. The flange portion is slidably engaged 
with the dimples. 
Another aspect of the invention provides a method for shielding 
electromagnetic interference (EMI) and fastening housing members. A top 
housing member and a bottom housing member is provided. The top housing 
member includes a top side including an inner surface. The bottom housing 
member includes a flange portion. A clip including a first longitudinal 
portion and a second longitudinal portion is also provided. The first 
longitudinal portion is fastened to the inner surface of the top side of 
the top housing member. The second longitudinal portion includes a 
plurality dimples formed therein, and a plurality of step portions spaced 
along and between the first and second longitudinal portions. The flange 
portion of the bottom housing member is slidably engaged with the 
plurality of dimples. The second longitudinal portion is deflected. The 
plurality of dimples of the second longitudinal portion is biased against 
the flange portion to fasten the top housing member and the bottom housing 
member together and to prevent electromagnetic emissions from exiting 
between the top housing member and a bottom housing member. 
The invention provides the foregoing and other features, and the advantages 
of the invention will become further apparent from the following detailed 
description of the presently preferred embodiments, read in conjunction 
with the accompanying drawings. The detailed description and drawings are 
merely illustrative of the invention and do not limit the scope of the 
invention, which are defined by the appended claims and equivalents 
thereof.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
As shown in FIG. 1 a preferred embodiment of an electromagnetic 
interference (EMI) shield and fastener apparatus 10 includes a clip 12 for 
fastening to a first housing member 14 including a length. As shown in 
FIGS. 1-3, the clip 12 includes a plurality of longitudinally oriented 
openings 16 formed therein. The openings 16 are preferably rectangular in 
shape. The clip also includes a plurality of dimples 18 formed therein 
spaced along the length of the clip 12 for engaging with a second housing 
member 20. 
As shown in FIGS. 1 and 4, the first housing member 14 is a top housing 
member and the second housing member 20 is a bottom housing member. The 
top housing member 14 includes a top side 26 including an inner surface 
28. The bottom housing member 20 includes a flange portion 30. 
The clip 12 preferably includes a first longitudinal portion 22 and a 
second longitudinal portion 24. The first longitudinal portion 22 is 
preferably fastened to a first housing member 14. As shown in FIG. 4, the 
first longitudinal portion 22 may preferably be fastened to the inner 
surface 28 of the top side 26 of the top housing member 14. The fastening 
may be accomplished by any conventional means such as, for example, spot 
welding. Other fastening means may be used including, for example, rivets 
or screws. The second longitudinal portion 24 includes a plurality of 
dimples 18 formed therein. As shown in FIGS. 2-4, the second longitudinal 
portion 24 may include a flange portion 25 oriented along the length of 
the second longitudinal portion 24 to guide the flange portion 30 of the 
bottom housing member 20 into contact with the dimples 18. 
The clip 12 may preferably be formed from a single piece of conductive 
material. The conductive material may preferably be any suitable 
conductive material such as, for example, stainless steel. Other types of 
conductive material may be used, including copper. The clip 12 may 
preferably be rectangular in shape. The clip 12 may be configured in a 
wide variety of other shapes to conform with the shape of the top housing 
member 14 and the bottom housing member 20. 
As shown in FIGS. 2-4, the plurality of dimples 18 may preferably be spaced 
along the second longitudinal portion 24 for contacting with the second 
housing member 20. The number of dimples 18 may vary depending on the 
particular application and the amount of friction that is desired between 
the dimples 18 and the flange portion 30 of the bottom housing member 20. 
As shown in FIGS. 2-3, the plurality of dimples 18 may preferably be 
equally spaced apart along the second longitudinal portion 24 and between 
a plurality of step portions 32. Alternatively, the dimples may be spaced 
along the second longitudinal portion 24 at varying intervals. The 
plurality of dimples 18 may preferably have a curved contact surface 34. 
Alternatively, the contact surface 34 may have a different shape depending 
on the particular application and the amount of friction desired between 
the contact surface 34 and the flange portion 30 of the bottom housing 
member 20. 
As shown in FIGS. 2-3, the plurality of step portions 32 are spaced along 
and between the first longitudinal portion 22 and the second longitudinal 
portion 24. The step portions 32 may preferably be oriented substantially 
perpendicular to the first longitudinal portion 22 and the second 
longitudinal portion 24. 
The apparatus shown in FIGS. 14 is used for shielding electromagnetic 
interference (EMI) and fastening housing members together. The flange 
portion 30 of the bottom housing member 20 is slidably engaged with the 
plurality of dimples 18. The second longitudinal portion 24 of the clip 12 
is deflected and biases the plurality of dimples 18 of the second 
longitudinal portion 24 against the flange portion 30. One advantage of 
the present invention is that a continuous seal is formed between the top 
housing member 14 and the bottom housing member 20 which prevents 
electromagnetic radiation from exiting the housing. Moreover, this 
invention eliminates the need for screws or other mechanical fasteners to 
fasten the top housing member 14 and the bottom housing member 20 
together. 
While the embodiments of the invention disclosed herein are presently 
considered to be preferred, various changes and modifications can be made 
without departing from the spirit and scope of the invention. The scope of 
the invention is indicated in the appended claims, and all changes that 
come within the meaning and range of equivalents are intended to be 
embraced therein.