Integrated shield wrap

Details Integrated shield wrap Integrated shield wrap

2002-01-29

2004-01-06

Martin, David (Department: 2841)

Electricity: electrical systems and devices

Housing or mounting assemblies with diverse electrical...

For electronic systems and devices

C361S816000, C361S818000, C361S787000, C174S034000, C174S034000, C439S607070

Reexamination Certificate

active

06674652

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
BACKGROUND
1. Technological Field
The present invention relates generally to devices and systems concerned with insulation of various electronic components and the control and management of electromagnetic wave emissions. More particularly, embodiments of the present invention relate to an integrated shield wrap that may be employed in various devices and systems to facilitate effective and efficient implementation of desired shielding and insulation functionality.
2. Related Technology
Many devices include electronic circuitry that naturally emits electromagnetic waves in various frequencies. Examples of such devices include personal data assistants (“PDA”), wireless telephones, video game machines, televisions, stereo equipment, medical equipment, computers, peripheral devices such as modems and printers, and media readers, such as compact disk drives and magnetic disk drives. Additionally, various types of expansion cards, such as those conforming to Personal Computer Memory Card International Association (“PCMCIA”) card standards, typically employ such electronic circuitry. In some cases, the electromagnetic waves emitted by such devices are radio frequency (“RF”) waves. Generally, RF waves refer to those electromagnetic waves having frequencies above the audio range but below the visible light range, typically between 30 KHz and 300 GHz. Electromagnetic waves of various other frequencies may also be emitted by the aforementioned, and other, electronic devices.
Such emission of electromagnetic waves is problematic because electromagnetic waves, or electromagnetic radiation, oftentimes adversely affects the performance of circuitry located in the vicinity of the circuitry emitting the electromagnetic radiation, and the electromagnetic radiation may also compromise the performance integrity of the electronic equipment within which the emitting electronic circuitry is employed. The undesirable effects produced by such electromagnetic radiation are sometimes referred to as electromagnetic interference (“EMI”). Because of the aforementioned, and other, adverse effects that flow from the emission of electromagnetic radiation, it is often desirable to interpose some type of shielding between the circuitry emitting the electromagnetic radiation and the circuitry or other devices which are desired to be protected.
One factor that complicates the design and placement of such shielding, however, is that while it is desirable to shield particular electronic circuitry, it is also necessary in many cases to insulate that electronic circuitry from other circuitry or components within the device. Specifically, because shielding must be electrically conductive in order to be able to control electromagnetic radiation, the nature of shielding material is inherently incompatible with the electrically insulative material that necessarily comprises an insulator such as would be used to insulate the electronic circuitry from other circuitry or components. Notwithstanding this inherent contradiction, a variety of approaches to addressing these issues can be conceived.
For example, it may be possible to construct an insulative protective wrap having a conductive shield layered into the wrap. One drawback to such a construction, however, is that the resulting wrap would be relatively thick and thus would reduce the usable volume defined by the particular device within which the insulative protective wrap was employed. Such a drawback is particularly problematic where relatively small devices, mini-peripheral component interconnect (“PCI”) expansion cards for example, are concerned.
Alternatively, a shield could be constructed so as to completely enclose the particular electronic circuitry whose electromagnetic emissions are to be managed and controlled. An insulative wrap could then be placed over the whole so as to provide the necessary insulative functionality with respect to such electronic circuitry. Such an approach however, raises some concerns.
In particular, because the shield would likely be soldered onto the printed circuit board (“PCB”) wherein the electronic circuitry is located, the shield would have to be cut into, or otherwise modified or removed, using a soldering iron or other tool in the event it was desired to make modifications to the PCB electronic circuitry within the shield. Accordingly, this type of unified shield arrangement, where the shield is of a one-piece construction, implicates additional costs in the event it is desired to perform rework on the PCB circuitry. In addition to the foregoing, there is at least one other point to be considered with respect to single piece shields.
Specifically, it is sometimes necessary to melt or “reflow” the solder on a PCB so as to allow the removal of selected electronic components and/or the installation of other electronic components. However, because it is important to the effectiveness of some shields that they substantially enclose the electronic circuitry whose electromagnetic emissions are to be controlled, there is typically little or no airflow within the volume bounded by the shield. Consequently, this type of shield may prevent, or otherwise compromise, the reflow of solder connections located within the shield boundary.
As suggested above, one approach to resolving the aforementioned reflow concerns may be to perforate the shield so as to allow at least some airflow within the volume bounded by the shield, and thereby permit reflow of the solder on the components located underneath the shield. Such an approach contradicts however, the intended purpose of the shield, that is, to control and manage electromagnetic emissions from the circuitry about which the shield is deployed. Specifically, perforations in the shield would permit leakage of electromagnetic radiation produced by the circuitry, and thereby compromise the overall performance of the shield and thus, other circuitry and/or components disposed within the device wherein the shield is employed.
As an alternative to the single-piece shield constructions considered above, the shield could be constructed in a two-piece configuration, with a removable lid for example, so that in the event rework is required, the lid could simply be removed and the rework performed. The lid could then be replaced upon completion of the rework. However, this type of multi-piece construction of the shield would implicate additional, and potentially more complicated, manufacturing and assembly processes, and thus, a relative increase in the overall costs associated with the device within which the shield is to be employed.
As an alternative to producing a multi-part shield that includes a lid portion, it is possible to simply position an electrically conductive “fence” around the electronic circuitry whose electromagnetic radiation is desired to be controlled, and then place an electrically conductive “sticker” or label on top of the fence to seal off the electronic circuitry. This type of approach, however, implicates additional production costs. In particular, the placement of the fence, and then the sticker, requires two different production steps. Further, once those two steps have been performed, the insulative wrap must then be installed, adding yet a third step to the overall process. Multiple step approaches such as these complicate the manufacturing process and add to the overall cost of the device in which the shield is employed.
Accordingly, what is needed is an integrated shield wrap having features directed to addressing the foregoing exemplary considerations, as well as other considerations not specifically enumerated herein. An exemplary integrated shield wrap should be of simple construction and should be capable of, among other things, facilitating effective and efficient implementation of desired shielding and insulation functionality with respect to selected electronic circuitry contained within an electronic device.
BRIEF SUMMARY OF AN EMBODIMENT OF THE INVENTION
In general, embodiments of the invention are conce

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