Electronic device enclosure having electromagnetic energy containment and heat removal characteristics

An enclosure for integrated circuit devices is disclosed. The enclosure includes a first portion which substantially encloses a plurality of secondary, relatively low-power integrated circuit devices and which includes a mechanism for contacting the secondary integrated circuit devices in order to conduct heat away. The enclosure also includes a second portion, which may include an active cooling device, directly in contact with a primary, relatively high-power primary integrated circuit device. In addition to removing heat, the first and second enclosure portions together shield the integrated circuit devices to contain electromagnetic energy generated by the devices. The first and second enclosure portions also allow different levels of force to be applied to the primary and secondary devices.

FIELD OF THE INVENTION 
The present invention relates generally to electronic device enclosures 
and, more particularly, to electronic device enclosures having the ability 
to contain electromagnetic energy and remove heat generated by electronic 
devices during operation. 
BACKGROUND OF THE INVENTION 
Integrated circuit devices are increasingly being used in modern electronic 
applications. One prevalent example of such an application is the 
computer. A typical computer may, for example, include a relatively large 
central processing unit which may be surrounded by a plurality of 
secondary electronic components such as cache SRAM memory devices. Both 
the central processing unit and the secondary components are generally 
constructed as integrated circuit devices which are mounted on a printed 
circuit board. 
Integrated circuit devices inherently emit electromagnetic radiation during 
operation. This electromagnetic radiation may cause interference with 
communication devices, such as telephones, radios, and televisions. As the 
power and sophistication of integrated circuit devices have increased, so 
has the level of electromagnetic interference generated by such devices. 
In order to prevent the interference described above, integrated circuit 
devices are often shielded in order to reduce or eliminate the 
electromagnetic radiation which is able to escape from the electronic 
component. To produce such shielding in a computer, for example, both the 
central processing unit and the secondary electronic components may be 
encased in an electrically conductive enclosure in order to block the 
emission of electromagnetic radiation. 
During normal operation, integrated circuit devices also generate 
significant amounts of heat. If this heat is not continuously removed, the 
integrated circuit device may overheat, resulting in damage to the device 
and/or a reduction in operating performance. Along with an increase in 
electromagnetic radiation, the increased power and sophistication of 
integrated circuit devices over the years has also resulted in an increase 
in heat generated by the devices and, thus, increases the difficulty of 
cooling the devices. 
In order to accomplish such heat removal, integrated circuit cooling 
devices are often used in conjunction with integrated circuit devices. One 
example of such a cooling device is a fan assisted heat sink cooling 
device. In such a device, a heat sink is formed of a material, such as 
aluminum, which readily conducts heat. The heat sink is usually placed on 
top of and in contact with the integrated circuit device. Due to this 
contact, heat generated by the integrated circuit is conducted into the 
heat sink and away from the integrated circuit. 
The heat sink may include a plurality of cooling fins in order to increase 
the surface area of the heat sink and, thus, maximize the transfer of heat 
from the heat sink into the surrounding air. In this manner, the heat sink 
is able to draw heat away from the integrated circuit and transfer the 
heat into the surrounding air. 
In order to enhance the cooling capacity of such a heat sink device, an 
electrically powered fan is often mounted in proximity to the heat sink. 
In operation, the fan causes air to move over and around the fins of the 
heat sink device, thus cooling the fins by enhancing the transfer of heat 
from the fins into the ambient air. 
An example of a fan assisted heat sink device which may be used to cool 
electronic components is described in U.S. patent application Ser. No. 
08/593,185, filed Feb. 1, 1996 of Guy R. Wagner for FAN ASSISTED HEAT SINK 
DEVICE which is hereby specifically incorporated by reference for all that 
is disclosed therein. 
It has been found, however, that the use of an electromagnetic containment 
enclosure, in a manner as previously described, interferes with the 
ability of an integrated circuit cooling device, such as a fan assisted 
cooling device, to adequately cool the integrated circuit device located 
within the containment enclosure. As previously described, it is necessary 
for a cooling device to be in direct contact with the integrated circuit 
device in order for the cooling device to efficiently conduct heat away 
from the integrated circuit device. Because the electromagnetic 
containment enclosure must completely surround the integrated circuit 
device, however, the cooling device would have to be located within the 
electromagnetic enclosure in order to be in contact with the electronic 
circuit device being cooled. Locating the cooling device within the 
enclosure in this manner would interfere with the ability of the cooling 
device to transfer heat into the surrounding air and, thus, would prevent 
the cooling device from efficiently cooling the electronic component. 
It has also been found that the mounting mechanisms for integrated circuit 
devices often interfere with the optimum operation of integrated circuit 
cooling devices. The mounting arrangement of many integrated circuit 
devices, e.g., a central processing unit of a computer, requires that the 
integrated circuit device be clamped to the printed circuit board with a 
certain level of force. To provide this force, clamping mechanisms are 
generally provided which contact the top of the integrated circuit device 
and thereby clamp the integrated circuit device to the printed circuit 
board. The location of such clamping mechanisms often prevents a cooling 
device from directly contacting the integrated circuit device and, thus, 
prevents the cooling device from properly cooling the integrated circuit 
device. 
Thus, it would be generally desirable to provide an apparatus which 
overcomes these problems associated with integrated circuit device 
electromagnetic containment and cooling. 
SUMMARY OF THE INVENTION 
The present invention is directed to an enclosure for integrated circuit 
devices. The enclosure may include a first part which substantially 
encloses a plurality of relatively low-power secondary integrated circuit 
devices mounted on a pc board. The enclosure first part may include a 
mechanism for contacting the secondary integrated circuit devices in order 
to conduct heat away from the secondary devices and thus cool the devices. 
The enclosure first part may be provided with cooling fins to facilitate 
this cooling function. 
The enclosure may also include a second part which may include an active 
cooling device which is directly in contact with a relatively high-power 
primary integrated circuit device mounted on the pc board. The active 
cooling device serves to cool the primary integrated circuit device. 
The enclosure first part may be configured to allow a first level of 
controlled force to be applied to the secondary integrated circuit 
devices. The enclosure second part may be configured to allow a second 
level of controlled force, independent of the first level of controlled 
force, to be applied to the primary integrated circuit device. The ability 
to independently supply force to the primary and secondary devices 
facilitates mounting of the devices on the pc board and reduces the risk 
of damage to the devices which might otherwise be caused by the 
application of excessive force. 
The first and second enclosure parts may, together, completely enclose the 
primary and secondary integrated circuit devices and may be electrically 
interconnected such that the enclosure also serves to block 
electromagnetic energy generated by the devices from escaping from the 
enclosure.

DETAILED DESCRIPTION OF THE INVENTION 
FIGS. 1-14, in general, illustrate an enclosure mounted on a printed 
circuit board 10 in proximity to at least one primary integrated circuit 
device 12 and at least one secondary electronic component 14 which are 
mounted on the printed circuit board 10. The enclosure includes a first 
enclosure portion 100 including an upper wall member 102 extending 
substantially parallel to the printed circuit board 10, wherein the upper 
wall member 102 has a lower surface 106 facing the printed circuit board 
10, an upper surface 104 opposite the lower surface 106 and at least one 
opening 136 therein located proximate the at least one primary integrated 
circuit device 12; a plurality of leg wall members 108, 110, 112, 114, 
116, 118 extending transversely from the upper wall member 102 toward an 
upper surface 38 of the printed circuit board 10; at least one contact 
member 142 extending from the upper wall member lower surface 106 toward 
the printed circuit board upper surface 38, wherein the at least one 
contact member 142 is in contact with the at least one secondary component 
14. The enclosure may also include at least one cooling device 250 having 
a lower surface 278 in contact with the at least one primary integrated 
circuit device 12; and wherein the at least one cooling device 250 is 
located within the at least one first enclosure portion opening 136 and is 
in electrical contact with the first enclosure portion 100. 
FIGS. 1-14 also illustrate, in general, an enclosure mounted on a printed 
circuit board 10 in proximity to at least one primary integrated circuit 
device 12 mounted on the printed circuit board 10. The enclosure may 
include a first enclosure portion 100 in contact with an upper surface 38 
of the printed circuit board 10 and including at least one opening 136 
therein located proximate the at least one primary integrated circuit 
device 12; at least one cooling device 250 in contact with the at least 
one primary integrated circuit device 12; and wherein at least a portion 
of the at least one cooling device 250 is located within the at least one 
first enclosure portion opening 136 and is in electrical contact with the 
first enclosure portion 100. 
FIGS. 1-14 also illustrate, in general, a method of enclosing at least one 
primary integrated circuit device 12 and at least one secondary electronic 
component 14 which are mounted on a printed circuit board 10. The method 
may include the steps of providing a first enclosure portion 100 having at 
least one opening 136 located therein; mounting the first enclosure 
portion on a first surface 38 of the printed circuit board 10 and 
contacting the at least one secondary component 14 with the first 
enclosure portion 100 to apply a first level of force to the at least one 
secondary component 14; providing at least one cooling device 250; placing 
at least a part of the at least one cooling device 250 within the at least 
one first enclosure portion opening 136 and contacting the at least one 
primary integrated circuit device 12 with the at least a part of the at 
least one cooling device 250 to apply a second level of force to the at 
least one primary integrated circuit device 12; and establishing 
electrical contact between the at least one cooling device 250 and the 
first enclosure portion 100. 
Having thus described the enclosure in general, the device will now be 
described in further detail. 
FIG. 1 illustrates a printed circuit board 10. A primary integrated circuit 
device 12 may be mounted on an upper surface 38 of the printed circuit 
bard 10 as shown. Primary integrated circuit device 12 may be a central 
processing unit for a computer and may, for example, be a central 
processing unit of the type commercially available from Hewlett-Packard 
Company and sold as a "PA-7200" processor. Surrounding the primary 
integrated circuit device 12 are a plurality of secondary integrated 
circuit devices 14, such as the individual secondary integrated circuit 
devices 16, 18, 20, 22, 24, 26, 28, 30, 32, 34 and 36. Secondary 
integrated circuit devices 14 may, for example, be cache SRAM memory 
devices. Referring to FIG. 2, it can be seen that some of the secondary 
integrated circuit devices 14, e.g., the secondary devices 16, 18, 20, 22, 
24, 30, 32, 34 and 36, may extend completely through the pc board 10 and 
project from the bottom surface 40 of the pc board 10. 
PC board 10 may include other electronic components, schematically 
illustrated by reference numeral 42 in FIG. 1, and a connection device 44 
in a conventional manner. Connection device 44 may be provided to allow 
the integrated circuit devices located on the pc board 10 to interface 
with electronic components located elsewhere. In the case of a computer, 
for example, the connection device 44 may allow the pc board to 
communicate with such user interface devices as a monitor and a keyboard. 
Integrated circuit devices, such as the primary integrated circuit device 
12 and the secondary integrated circuit devices 14, inherently emit 
electromagnetic radiation during operation. This electromagnetic radiation 
may cause interference with communication devices, such as telephones, 
radios, and televisions. It is, therefore, desirable to block this 
radiation to prevent such interference. 
In addition, integrated circuit devices, such as the primary integrated 
circuit device 12 and the secondary integrated circuit devices 14, 
typically generate significant amounts of heat during operation. In order 
to prevent damage to and/or reduced efficiency of the integrated circuit 
devices, it is necessary to remove this heat by cooling the devices during 
operation. This is particularly true with respect to the primary 
integrated circuit device because this device tends to draw more power 
and, thus, generate more heat than do the secondary integrated circuit 
devices 14. 
An enclosure which effectively blocks electromagnetic radiation generated 
by the primary integrated circuit device 12 and the secondary integrated 
circuit devices 14 and which provides for adequate cooling of the devices 
12 and 14 will now be described in detail. 
Referring to FIGS. 1 and 2, it can be seen that the enclosure may generally 
include an upper enclosure portion 100 which is adapted to contact the 
upper surface 38 of the pc board 10, FIG. 1, and a lower enclosure portion 
300 which is adapted to contact the lower surface 40 of the pc board 10, 
FIG. 2. 
Upper enclosure portion 100 may be generally formed from a substantially 
planar top wall member 102 which may include an upper surface 104, FIG. 3 
and a lower surface 106, FIG. 4. Extending transversely downwardly from 
the top wall member 102 are a plurality of side wall members 108, 110, 
112, 114, 116 and 118, FIGS. 2 and 4. The side wall members 108, 110, 112, 
114, 116 and 118 may be integrally formed with the top wall member 102. 
Each of the side wall members may include a downwardly facing end portion 
120, 122, 124, 126, 128 and 130, respectively. Upper enclosure portion 100 
may have an overall height "o" of about 11.2 mm, FIG. 5. 
Referring to FIG. 3, a first and second set of cooling fins 132, 134 may 
extend upwardly from the top wall member upper surface 104. Each of the 
fins may extend a distance "a" of about 15 mm above the top wall member 
upper surface 104, FIG. 5. An opening 136 may be provided in the top wall 
member 102 as shown. Referring to FIGS. 4 and 5, it can be seen that the 
opening 136 may be surrounded by a flange portion 138. The flange portion 
138 may be integrally formed with the top wall member 102 and may extend a 
distance "b" of about 6.9 mm below the top wall member upper surface 104, 
FIG. 5. Referring again to FIG. 3, the opening 136 may be substantially 
rectangular and have a length "d" of about 65.6 mm and a width "e" of 
about 54.7 mm. A beveled surface 140 may be provided between the top wall 
member upper surface 104 and the opening flange 138 as shown. 
Referring to FIGS. 4 and 5, a plurality of bosses 142 such as the 
individual bosses 146, 148, 150, 152, 154, 156, 158, 160, 162, 164 and 166 
may extend downwardly from the top wall member lower surface 106 as shown. 
The bosses 142 may be integrally formed with the top wall member 102 and 
may extend for the distance "b" of about 6.9 mm below the top wall member 
upper surface 104, FIG. 5. The bosses 142 may be have a generally 
rectangular cross-section as shown and may be sized and arranged to 
correspond to the size and arrangement of the secondary integrated circuit 
devices 14 located on the pc board 10, FIG. 1. Referring to FIG. 4, each 
boss may be provided with a series of slots, such as the slots 168, 170, 
172 in the boss 154. 
As shown in FIG. 2, compliant thermal interface pads 174 may be attached to 
each of the bosses 142 as shown, for example, with respect to the 
compliant thermal interface pads 176, 178, 180 attached to the bosses 156, 
158, 160, respectively. When the upper enclosure portion 100 is mounted on 
the pc board 10 as shown, for example, in FIG. 7, the interface pads 174 
will be compressed between the bosses 142 and the respective secondary 
integrated circuit devices 14. In this manner, the interface pads 174 
assist in conducting heat from the secondary integrated circuit devices 
through the bosses 142 and into the remainder of the upper enclosure 
portion 100 as will be explained in more detail herein. Compliant thermal 
interface pads 174 may each have a thickness of approximately 0.125 inches 
and may be sized and shaped to correspond generally to the size and shape 
of the bosses 142. The compliant thermal interface pads 174 may be made of 
a material commercially available from Bergquist Company of Minneapolis, 
Minn. and sold as "Gap Pad" thermal interface sheet. 
Upper enclosure portion 100 may be provided with a plurality of 
through-holes 182, 184, 186, 188 and 190 as shown, for example, in FIGS. 3 
and 4. These holes may align with a plurality of holes 52, 54, 56, 58 and 
60, respectively, located in the pc board 10, FIG. 1, to facilitate 
mounting of the upper enclosure portion 100 on the pc board 10 as will be 
explained in further detail herein. Upper enclosure portion 100 may be 
formed of a material which is both electrically conductive and which 
readily conducts heat. In this manner, upper enclosure portion 100 may 
serve to both conduct heat away from the secondary integrated circuit 
devices 14 and to contain electromagnetic energy generated by the 
integrated circuit devices 12 and 14 as will be explained in further 
detail herein. Upper enclosure portion 100 may, for example, be formed of 
aluminum generally having a thickness of about 3 mm. 
Referring to FIG. 5, resilient contact fingers 192 may be extend downwardly 
from each of the side wall member end portions 120, 122, 124, 126, 128 and 
130. The fingers 192 are adapted to contact a metallized ground pad 62 
located on the upper surface 38 of the pc board 10, FIG. 1, when the upper 
enclosure portion 100 is mounted on the pc board 10. This contact between 
the fingers 192 and the ground pad 62 facilitates electrical contact 
between the upper enclosure portion 100 and the pc board ground and, thus, 
enhances the ability of the upper enclosure portion 10 to contain 
electromagnetic interference generated by the integrated circuit devices 
12 and 14, as will be explained in more detail herein. The fingers 192 may 
be integrally formed with a leg member 194 which may be adhered to the 
inside surface of the side wall portions 108, 110, 112, 114, 116 and 118 
in a conventional manner. The contact fingers 192 may be of the type 
commercially available from Instrument Specialties Co. of Delaware Water 
Gap, Pa. and sold as "Sticky Fingers" EMI gasketing material. It is noted 
that, for purposes of clarity, the contact fingers 192 are not shown in 
FIG. 4. 
Referring to FIG. 6, a cooling device 250 may be provided as shown. Cooling 
device 250 may generally be constructed having a heat sink portion 252 and 
a fan 254 located within the heat sink portion 252, FIG. 7. Cooling device 
250 may be of the type disclosed in the previously referenced U.S. patent 
application Ser. No. 08/593,185 or may, alternatively, be any conventional 
type of cooling device used to remove heat from electronic components. In 
order to facilitate containment of electromagnetic radiation from the 
integrated circuit devices 12 and 14, as will be explained in more detail 
herein, the heat sink portion 252 should be constructed of an electrically 
conductive material such as aluminum. A power cable 260 may be provided as 
shown in order to deliver electrical energy to the fan 254 located within 
the heat sink 252 in a conventional manner. 
Referring again to FIG. 6, a pedestal 256 may extend from a lower surface 
258 of the cooling device heat sink portion 252. The pedestal 256 may be 
integrally formed with the heat sink 252 and may be generally rectangular, 
having a length "f" of about 64.6 mm and a width "g" of about 53.7 mm. The 
pedestal 256 may extend a distance of about 7 mm below the heat sink lower 
surface 258 and may include a lower surface 278 as shown. 
A groove 262 may be provided around a lower portion of the pedestal 256 as 
shown. An electrically conductive, compressible O-ring 264 may be provided 
as shown, and may be sized to fit securely within the groove 262 in a 
conventional manner. O-ring 264 may be in the form of a metallic spring 
and may be of the type commercially available from Bal Seal Engineering 
Company of Santa Ana, Calif. and sold as part no. 105LB. The pedestal 256 
may be provided with a plurality of threaded holes 266, 268, 270 and 272 
and with a pair of non-threaded holes 274 and 276 as shown. 
When the cooling device 250 is mounted on the upper enclosure portion 100, 
as shown in FIG. 7, the cooling device pedestal 256 fits within the upper 
enclosure portion opening 136. When so mounted, the compressible O-ring 
264 will be compressed between the pedestal groove 262 and the upper 
enclosure portion flange 138, FIGS. 1 and 5. The contact between the upper 
enclosure portion flange 138, the conductive O-ring 264 and the cooling 
device pedestal groove 262 facilitates electrical contact between the 
upper enclosure portion 100 and the cooling device 250 and, thus, enhances 
the ability of the upper enclosure portion 100 and attached cooling device 
250 to contain electromagnetic interference generated by the integrated 
circuit devices 12 and 14, as will be explained in more detail herein. 
When inserting the cooling device pedestal 256 into the upper enclosure 
portion opening 136, the beveled surface 140, FIG. 3, facilitates 
compression of the compressible O-ring 264. 
Referring to FIGS. 8-10, lower enclosure portion 300 may be generally 
formed from a substantially planar bottom wall member 302 which may 
include an upper surface 304, FIG. 8 and a lower surface 306, FIG. 9. 
Extending transversely upwardly from the bottom wall member 302 are a 
plurality of side wall members 308, 310, 312, 314, 316 and 318, FIGS. 1 
and 8. The side wall members 308, 310, 312, 314, 316 and 318 may be 
integrally formed with the bottom wall member 302. Each of the side wall 
members may include an upwardly facing end portion 320, 322, 324, 326, 328 
and 330, respectively. Lower enclosure portion 300 may have an overall 
height "p" of about 7.9 mm, FIG. 10. 
As can be seen from FIGS. 8 and 9, an opening 336 may be provided in the 
bottom wall member 302 as shown. Referring to FIGS. 1 and 8, it can be 
seen that the opening 336 may be surrounded by a flange portion 338. The 
flange portion 338 may be integrally formed with the bottom wall member 
302 and may extend a distance "h" of about 3.7 mm above the bottom wall 
member lower surface 306, FIG. 10. Referring again to FIG. 8, the hole 336 
may be substantially rectangular and have a length "j" of about 65.6 mm 
and a width "k" of about 54.7 mm. A beveled surface 340, FIG. 9, may be 
provided between the bottom wall member lower surface 306 and the opening 
flange 338 as shown. 
Referring to FIGS. 8 and 10, a plurality of bosses 342 such as the 
individual bosses 346, 348, 350, 352, 354, 360, 362, 364 and 366 may 
extend upwardly from the bottom wall member upper surface 304 as shown. 
The bosses 342 may be integrally formed with the bottom wall member 302 
and may extend for a distance "i" of about 3.6 mm above the bottom wall 
member lower surface 304, FIG. 10. The bosses 342 may be have a generally 
rectangular cross-section as shown and may be sized and arranged to 
correspond to the size and arrangement of the secondary integrated circuit 
devices 14 located on the pc board 10, FIG. 2. It is noted that the number 
and arrangement of the lower enclosure portion bosses 342 need not be 
identical to that of the upper enclosure portion 100, as previously 
described. Comparing FIG. 1 with FIG. 2, it can be seen, for example, that 
the lower enclosure portion lacks any bosses corresponding in location to 
the upper enclosure bosses 156 and 158. This is because the secondary 
integrated circuit devices 26 and 28, which correspond to the upper 
enclosure portion bosses 156 and 58 respectively, do not extend completely 
through the pc board 10 and project from the bottom surface 40 of the pc 
board as do the remainder of the secondary integrated circuit devices 14. 
Referring again to FIG. 8, each boss 42 may be provided with a series of 
slots, such as the slots 368, 370, 372 in the boss 354. 
As shown in FIG. 1, compliant thermal interface pads 74 may be attached to 
each of the bosses 342 as shown, for example, with respect to the 
compliant thermal interface pads 376, 378, 380 attached to the bosses 362, 
364, 366, respectively. When the lower enclosure portion 300 is mounted on 
the pc board 10, the interface pads 374 will be compressed between the 
bosses 342 and the respective secondary integrated circuit devices 14. In 
this manner, the interface pads 374 assist in conducting heat from the 
secondary integrated circuit devices through the bosses 342 and into the 
remainder of the lower enclosure portion 300 as will be explained in more 
detail herein. The compliant thermal interface pads 374 may each have a 
thickness of approximately 0.125 inches and may be sized and shaped to 
correspond generally to the size and shape of the bosses 342. The 
compliant thermal interface pads 374 may be identical to the thermal 
interface pads 174, previously described. 
Lower enclosure portion 300 may be provided with a plurality of threaded 
holes 382, 384, 386, 388 and 390 as shown, for example, in FIGS. 8 and 9. 
These holes may align with the plurality of holes 52, 54, 56, 58 and 60, 
respectively, located in the pc board 10, FIG. 1, to facilitate mounting 
of the lower enclosure portion 300 on the pc board 10 as will be explained 
in further detail herein. Lower enclosure portion 300 may be formed of a 
material which is both electrically conductive and which readily conducts 
heat. In this manner, lower enclosure portion 300 may serve to both 
conduct heat away from the secondary integrated circuit devices 14 and to 
contain electromagnetic energy generated by the integrated circuit devices 
12 and 14 as will be explained in further detail herein. Lower enclosure 
portion 300 may, for example, be formed of aluminum generally having a 
thickness of about 3 mm. 
Referring to FIG. 10, resilient contact fingers 392 may be extend upwardly 
from each of the side wall member end portions 320, 322, 324, 326, 328 and 
330. The fingers 392 are adapted to contact a metallized ground pad 64 
located on the lower surface 40 of the pc board 10, FIG. 2, when the lower 
enclosure portion 300 is mounted on the pc board 10. This contact between 
the fingers 392 and the ground pad 64 facilitates electrical contact 
between the lower enclosure portion 300 and the pc board ground and, thus, 
enhances the ability of the lower enclosure portion 300 to contain 
electromagnetic interference generated by the integrated circuit devices 
14 and 16, as will be explained in more detail herein. The fingers 392 may 
be integrally formed with a leg member 394 which may be adhered to the 
inside surface of the side wall portions 108, 110, 112, 114, 116 and 118 
in a conventional manner. The contact fingers 392 may be identical to the 
contact fingers 192, previously described with respect to the upper 
enclosure portion 100. It is noted that, for purposes of clarity, the 
contact fingers 392 are not shown in FIG. 8. 
Referring to FIG. 11, a bolster plate 400 may be provided as shown. Bolster 
plate 400 may be generally rectangular, having a length "1" of about 64.6 
mm and a width "m" of about 53.7 mm. Bolster plate 400 may have an overall 
height "n" of about 8 mm. In order to facilitate containment of 
electromagnetic radiation from the integrated circuit devices 12 and 14, 
as will be explained in more detail herein, the bolster plate 400 should 
be constructed of an electrically conductive material such as aluminum. 
A groove 402 may be provided around a lower portion of the bolster plate 
400. An electrically conductive, compressible O-ring 404 may be provided 
as shown, and may be sized to fit securely within the groove 402 in a 
conventional manner. O-ring 404 may be in the form of a metallic spring 
and may be identical to the O-ring 264 previously described. Bolster plate 
400 may be provided with a plurality of non-threaded through holes 406, 
408, 410 and 412 as shown. 
When the bolster plate 400 is mounted on the lower enclosure portion 300, 
as shown in FIG. 12, the bolster plate fits within the lower enclosure 
portion opening 336. When so mounted, the compressible O-ring 404 will be 
compressed between the bolster plate groove 402 and the lower enclosure 
portion flange 338, FIGS. 8 and 10. The contact between the lower 
enclosure portion flange 338, the conductive O-ring 404 and the bolster 
plate groove 402 facilitates electrical contact between the lower 
enclosure portion 300 and the bolster plate 400 and, thus, enhances the 
ability of the lower enclosure portion 300 and attached bolster plate 400 
to contain electromagnetic energy generated by the integrated circuit 
devices 14 and 16, as will be explained in more detail herein. When 
inserting the bolster plate 400 into the lower enclosure portion opening 
336, the beveled surface 340, FIG. 9, facilitates compression of the 
compressible O-ring 404. 
The installation of the upper and lower enclosure portions 100, 300 on the 
pc board 10 will now be described in detail. Referring to FIG. 1, a 
plurality of screws 72, 74, 76, 78 and 80 may be passed through the holes 
182, 184, 186, 188 and 190, respectively, in the upper enclosure portion 
100, through the holes 52, 54, 56, 58 and 60, respectively, in pc board 10 
and may engage within the threaded holes 382, 384, 386, 388 and 390, 
respectively, in the lower enclosure portion 300. As can be appreciated, 
tightening the screws 72, 74, 76, 78 and 80 within the threaded holes 382, 
384, 386, 388 and 390, respectively, in the lower enclosure portion 300 
will cause the upper enclosure portion 100 to be securely clamped against 
the pc board upper surface 38 and the lower enclosure portion 300 to be 
securely clamped against the pc board lower surface 40. 
When the upper enclosure 100 is installed on the pc board 10, as described 
above, the compliant thermal interface pads 174 located on the upper 
enclosure bosses 142, FIG. 2, will be compressed against the upper 
surfaces of the respective secondary integrated circuit devices 14. Such 
compression ensures reliable surface contact between the thermal interface 
pads and the upper enclosure bosses 142 and between the thermal interface 
pads and the upper surfaces of the secondary integrated circuit devices 
14. 
This surface contact facilitates the efficient conduction of heat away from 
the secondary components 14, through the interface pads and into the upper 
enclosure bosses 142. From the bosses, the heat is further conducted into 
the upper enclosure portion top wall member 102 and then into the cooling 
fins 132, 134 for subsequent dissipation into the surrounding air. Further 
facilitating the efficient conduction of heat is the fact that the upper 
enclosure portion 100 is integrally formed, i.e., the bosses 142, the top 
wall member 102 and the cooling fins 132, 134 are formed from one piece of 
heat conductive material, e.g., aluminum. This one-piece construction 
minimizes the number of joints within the heat flow path and, thus, 
maximizes heat conductance. 
As described adore, it is desirable to provide some compression of the 
thermal interface pads 174 in order to facilitate heat removal from the 
secondary integrated circuit devices 14. It is also critical, however, to 
ensure that too much force is not applied to the secondary integrated 
circuit devices. Integrated circuit devices such as the secondary 
integrated circuit devices 14 are generally each attached to a pc board 
via a series of solder joints. Excessive force applied to such integrated 
circuit devices may, over time, damage these solder joints and impair the 
proper operation of the devices. It has been found, for example, that 
maintaining the compressive force on each secondary integrated circuit 
device at 5 lbs. or less is generally sufficient to ensure that the damage 
previously described does not occur and that the long-term reliability of 
the devices is not jeopardized. 
Once the upper enclosure portion 100 is seated against the pc board 10, 
i.e., when the resilient contact fingers 192 are completely compressed 
against the pc board upper surface ground pad 62, further tightening of 
the screws 72, 74, 76, 78 and 80 will have no effect on the amount of 
force supplied to the secondary integrated circuit devices 14. The amount 
of force supplied to the secondary integrated circuit devices 14 by the 
upper enclosure portion 100 is determined solely by the relationship 
between the height of the integrated circuit device extending above the pc 
board 10, the thickness and composition of the thermal interface pads 
used, and the height "c" of the bosses 142 relative to the overall height 
"o" of the upper enclosure portion 100, FIG. 5. It has been found that 
with an integrated circuit device having a height of about 0.1 inches, the 
exemplary dimensions previously set forth and the thermal interface pad 
material previously specified result in a force of less than 5 lbs. being 
applied to each secondary integrated circuit device and yet also result in 
adequate surface contact between the thermal interface pads 174 and the 
upper enclosure bosses 142 and between the thermal interface pads 174 and 
the upper surfaces of the secondary integrated circuit devices 14. It is 
to be understood, of course, that other dimensional relationships could 
easily be used to accommodate integrated circuit devices of varying size. 
Adequate surface contact between the thermal interface pads 174 and the 
upper enclosure bosses 142 and between the thermal interface pads and the 
upper surfaces of the secondary integrated circuit devices 14 is enhanced 
by the upper enclosure portion 100 in two additional ways. First, the 
slots in the bosses 142, such as the slots 168, 170, 172, FIG. 3, allow 
the thermal interface pad material to deform thereinto, thereby allowing 
the pads to deform rather than transmit a high level of force to the 
secondary integrated circuit devices 14. Second, the upper enclosure 
portion 100 is provided with a plurality of separate bosses, rather than 
one large boss. Because separate bosses are provided, each thermal 
interface pad may deform laterally in four directions, thus further 
allowing the pads to deform rather than to transmit a high level of force 
to the secondary integrated circuit devices 14. Both the slots and the 
separate boss arrangement allow the thermal interface pads to be 
compressed, thereby ensuring good surface contact with the boss and with 
the integrated circuit device, and yet not transmit high levels of force 
to the integrated circuit devices. 
When the lower enclosure 300 is installed on the pc board 10, as described 
above, the compliant thermal interface pads 374 located on the lower 
enclosure bosses 342, FIG. 2, will be compressed against the lower 
surfaces of the respective secondary integrated circuit devices 14. Such 
compression ensures reliable surface contact between the thermal interface 
pads and the lower enclosure bosses 342 and between the thermal interface 
pads and the lower surfaces of the secondary integrated circuit devices 
This surface contact facilitates the efficient conduction of heat away from 
the secondary components 14, through the interface pads 374 and into the 
lower enclosure bosses 342. From the bosses, the heat is further conducted 
into the lower enclosure portion bottom wall member 302 for subsequent 
dissipation into the surrounding air and/or into the material making up a 
computer case structure with which the lower enclosure portion bottom wall 
member 302 may be in contact. Further facilitating the efficient 
conduction of heat is the fact that the lower enclosure portion 300 is 
integrally formed, i.e., the bosses 342 and the bottom wall member 302 are 
formed from one piece of heat conductive material, e.g., aluminum. This 
one-piece construction minimizes the number of joints within the heat flow 
path and, thus, maximizes heat conductance. 
As in the case of the upper enclosure portion 100, as previously described, 
once the lower enclosure portion 300 is seated against the pc board 10, 
i.e., when the resilient contact fingers 392 are completely compressed 
against the pc board lower surface ground pad 64, further tightening of 
the screws 72, 74, 76, 78 and 80 will have no effect on the amount of 
force supplied to the secondary integrated circuit devices 14. The amount 
of force supplied to the secondary integrated circuit devices 14 is 
determined solely by the relationship between the height of the integrated 
circuit device extending below the pc board, the thickness and composition 
of the thermal interface pads used, and the height "i" of the bosses 342 
relative to the overall height "p" of the lower enclosure portion 300, 
FIG. 10. It has been found that, with an integrated circuit device having 
a height of about 0.1 inches, the exemplary dimensions previously set 
forth and the thermal interface pad material previously specified result 
in a force of less than 5 lbs. being applied to each secondary integrated 
circuit device by the lower enclosure portion 300 and yet also result in 
adequate surface contact between the thermal interface pads 374 and the 
lower enclosure bosses 342 and between the thermal interface pads 374 and 
the lower surfaces of the secondary integrated circuit devices 14. It is 
to be understood, of course, that other dimensional relationships could 
easily be used to accommodate integrated circuit devices of varying size. 
In a similar manner to the upper enclosure portion 100, adequate surface 
contact between the thermal interface pads 374 and the lower enclosure 
bosses 342 and between the thermal interface pads 374 and the lower 
surfaces of the secondary integrated circuit devices 14 is enhanced by the 
design of the lower enclosure portion 100 in two ways. First, the slots in 
the bosses 342, such as the slots 368, 370, 372, FIG. 8, allow the thermal 
interface pad material to deform thereinto, thereby allowing the pads to 
deform rather than transmit a high level of force to the secondary 
integrated circuit devices 14. Second, the lower enclosure portion 300 is 
provided with a plurality of separate bosses, rather than one large boss. 
Because separate bosses are provided, each thermal interface pad may 
deform laterally in four directions, thus further allowing the pads to 
deform rather than to transmit a high level of force to the secondary 
integrated circuit devices 14. Both the slots and the separate boss 
arrangement allow the thermal interface pads to be compressed, thereby 
ensuring good surface contact with the boss and with the integrated 
circuit device, and yet not transmit high levels of force to the 
integrated circuit devices. 
After installation of the upper and lower enclosure portions 100, 300, the 
cooling device 250 and bolster plate 400 may be installed as follows. 
First, if not already installed, the primary integrated circuit device 12 
may be installed on the pc board 10 as shown in FIG. 1. The cooling device 
pedestal 256, with its O-ring 264 mounted in the groove 262, may then be 
inserted into the upper enclosure opening 136 until the pedestal lower 
surface 278 contacts the upper surface of the primary integrated circuit 
device 12. The bolster plate 400, with its O-ring 404 mounted in the 
groove 402 then may be inserted into the lower enclosure opening 336 until 
the bolster plate contacts the lower surface 40 of the pc board 10. The 
non-threaded holes 274, 276 in the cooling device pedestal 256 may be 
provided to allow clearance for a pair of threaded studs 48, 50, FIG. 1, 
which sometimes exist on primary integrated circuit devices. 
Then, referring to FIG. 13, a plurality of screws 286, 288, 290, 292 may be 
passed through the holes 406, 408, 410, and 412, respectively, in the 
bolster plate 400, through a plurality of holes 86, 88, 90 and 92, FIG. 2, 
respectively, in the pc board 10 and may engage within the threaded holes 
266, 268, 270 and 272, respectively, in the cooling device 250. As can be 
appreciated, tightening the screws 286, 288, 290, 292 within the threaded 
holes 266, 268, 270 and 272 in the cooling device 250 will cause the 
bolster plate 400 to be securely clamped against the pc board lower 
surface 40 and the cooling device pedestal lower surface 278 to be 
securely clamped against the upper surface of the primary integrated 
circuit device 12. 
Because the primary integrated circuit device 12 generates a significant 
amount of heat (generally much more than the secondary integrated circuit 
devices 14), the cooling device 250 is designed to directly contact the 
upper surface of the primary device 12. In this manner, heat generated by 
the primary integrated circuit device 12 may be directly conducted into 
the cooling device pedestal 256 and thereafter into the remainder of the 
heat sink for dissipation into the surrounding air. The cooling device fan 
254 facilitates this heat transfer into the surrounding air in a 
conventional manner by moving air into the heat sink 252 in the direction 
of the arrow 296, FIG. 7, and then exhausting the air through the bottom 
of the fins of the heat sink 252. After exiting the heat sink 252, the air 
is forced to travel between the fins 132 and 134 of the upper enclosure 
portion 100, thus facilitating heat removal from the secondary integrated 
circuit devices 14 as well. 
Facilitating the efficient conduction of heat away from the primary 
integrated circuit device 12 is the fact that the cooling device 250 is 
integrally formed, i.e., the pedestal 256 and the remainder of the heat 
sink 252 are formed from one piece of heat conductive material, aluminum. 
This one-piece construction minimizes the number of joints within the heat 
flow path and, thus, maximizes heat conductance. 
Bolster plate 400 also serves to conduct heat away from the primary 
integrated circuit device 12 by contacting the lower surface 40 of the pc 
board 10 directly beneath the primary device 12. In this manner, the 
bolster plate 400 may conduct heat, which has been conducted through the 
pc board 10, away from the primary device 12 for subsequent dissipation 
into the surrounding air and/or into the material making up a computer 
case structure with which the bolster plate 400 may be in contact. 
The cooling device mounting arrangement described above may serve a purpose 
in addition to heat removal as will now be explained in detail. Many 
primary integrated circuit devices, such as primary device 12, are 
attached to a pc board mounting site through the use of compressive force. 
It is common, for example, to provide a compressible socket between the 
integrated circuit device and the pc board mounting site. A compressive 
force on the integrated circuit device is then required to compress the 
compressible socket and maintain electrical contact between the pc board 
site and the integrated circuit device. The compressive force required may 
be quite high and, in some situations, may be as much as 600 lbs. 
The cooling device mounting arrangement, as described above, provides a 
mechanism for clamping the primary integrated circuit device 12 to the pc 
board and, accordingly, for compressing a compressible socket device 
between the primary integrated circuit device 12 and the pc board 10. 
Specifically, the screws 286, 288, 290 and 92, FIG. 13, may be tightened 
in order to urge the cooling device 250 toward the pc board 10 and, by 
virtue of the contact between the cooling device pedestal lower surface 
278 and the primary device 12, also urge the primary device 12 toward the 
pc board 10. It is important to note that this force may be exerted 
independently of the force applied to the secondary integrated circuit 
devices 14 by the upper and lower enclosure portions 100, 300. As 
previously described, excessive force supplied to the secondary integrated 
circuit devices may cause damage to the secondary devices. The present 
design, thus, allows relatively high force to be applied to the centrally 
located primary integrated circuit device 12 while relatively low force is 
applied to the outlying secondary integrated circuit devices 14. 
It is noted that, in some cases, rather than using a compressible socket 
arrangement, primary integrated circuit devices are soldered directly to 
the pc board 10. In contrast to the compressible socket mounting 
arrangement previously described, solder mounting arrangements require 
that little or no force be applied to the primary integrated circuit 
device 12 since applied force may damage the solder joints between the 
device and the pc board. In such a situation, the cooling device 250 may 
be directly mounted to the primary integrated circuit device 12, for 
example, by the use of the threaded studs 48, 50, FIG. 1. To accomplish 
such a mounting, threaded nuts, not shown, may be provided on the ends of 
the studs 48, 50 which project into the interior of the cooling device 
heat sink 252. In this manner, the cooling device 250 may be securely 
mounted to the upper surface of the primary device 12 and may serve to 
cool the device as previously described. The screws 286, 288, 290 and 292 
may then be tightened only to the extent necessary to secure the bolster 
plate 400 in place. As can be appreciated, this mounting arrangement 
allows less force to be applied to the primary integrated circuit device 
by the cooling device 250 and bolster plate 400 than is applied to the 
secondary integrated circuit devices 14 by the upper and lower enclosure 
portions 100, 300. 
Once the upper and lower enclosure portions 100, 300, the cooling device 
250 and the bolster plate 400 have been installed, as described 
previously, the primary and secondary integrated circuit devices 12, 14 
will be completely shielded to prevent the emission of electromagnetic 
energy. Specifically, the upper enclosure portion 100 is in electrical 
contact with the pc board ground pad 62 via the compressible fingers 192. 
The upper enclosure portion 100 is also in electrical contact with the 
cooling device 250 via the conductive O-ring 264. Lower enclosure portion 
300 is in electrical contact with the pc board ground pad 64 via the 
compressible fingers 392. Lower enclosure portion 300 is also in 
electrical contact with the bolster plate 400 via the conductive O-ring 
404. Accordingly, as can be appreciated, the primary and secondary 
integrated circuit devices 12, 14 are completely enclosed within a 
conductive enclosure and electromagnetic energy generated by the devices 
12, 14 is, thus, effectively contained within the enclosure. In order to 
enhance the electrical continuity between the various components of the 
enclosure, the components, i.e., the upper and lower enclosures 100, 300, 
the cooling device 250 and the bolster plate 400 may be plated, for 
example, with a nickel plating material in a conventional manner. 
In summary, the enclosure described herein provides excellent containment 
of electromagnetic energy generated by the primary and secondary 
integrated circuit devices contained therein. The enclosure also provides 
for efficient heat removal from both the primary and secondary devices and 
allows separate levels of force to be applied to the primary and secondary 
devices. 
It is to be understood, that, although the pc board 10 has been described 
herein as having a particular configuration, the enclosure described 
herein may be adapted to be used with virtually any pc board 
configuration. Accordingly, the size, shape and configuration of the 
enclosure may vary according to the particular configuration of the pc 
board in question. 
In some applications, more than one primary electronic component may be 
provided on a pc board. In some computer applications, for example, it may 
be desirable to provide two or more central processing units in order to 
increase the data handling capability of the computer. FIG. 14 illustrates 
a pc board 510 upon which are mounted two primary electronic components 
512 (only one is shown). In all other respects, the pc board 512 may be 
identical to the pc board 10, previously described, and may contain a 
plurality of secondary electronic components generally surrounding the 
primary components 512, similar to the secondary components 14 of the pc 
board 10, as previously described. 
In order to enclose and cool the primary and secondary electronic 
components of the pc board 510, an upper enclosure portion 530 may be 
provided as shown. Upper enclosure portion 530 may include a pair of 
openings 536, 538. When the upper enclosure portion 530 is mounted on the 
pc board 510, the openings 536, 538 are each located proximate one of the 
primary electronic components 512. Each opening 536, 538 may be 
substantially identical to the opening 136 of the upper enclosure portion 
100 previously described. In all other respects, the upper enclosure 
portion 530 may be substantially identical to the upper enclosure portion 
100. The upper enclosure portion 530 may, for example, include a plurality 
of bosses, not shown, similar to the bosses 142, previously described with 
respect to the upper enclosure portion 100. The bosses of the upper 
enclosure portion 530 allow the upper enclosure portion 530 to both cool 
and apply the appropriate level of force to the secondary electronic 
components located on the pc board 510 in a similar manner to the bosses 
142 of the upper enclosure 100 as previously described. 
A pair of cooling devices 550, 560 may also be provided as shown in FIG. 
14. Each cooling device 550, 560 may be substantially identical to the 
cooling device 250 previously described except that a pair of flattened 
areas 552, 554 may be provided on the cooling device 550 and a pair of 
flattened areas 562, 564 may be provided on the cooling device 560 as 
shown. These flattened areas may be provided in order to provide clearance 
and allow two cooling devices, rather than one cooling device, to be 
mounted on the upper enclosure portion 530. When mounted on the upper 
enclosure portion 530, the cooling devices 550, 560 each contact an upper 
surface of one of the primary electronic components 512 in a similar 
manner to that previously described with respect to the cooling device 250 
and the primary component 12. 
A lower enclosure portion 600 may be provided on the lower surface of the 
pc board 510 as shown. The lower enclosure portion 600 may include a pair 
of openings, not shown, which may each be substantially identical to the 
opening 336 in the lower enclosure portion 300. The lower enclosure 
portion 600, in general, may be formed in a substantially identical manner 
to the lower enclosure portion 300 as previously described. The lower 
enclosure portion 600 may, for example, include a plurality of bosses, not 
shown, similar to the bosses 342, previously described with respect to the 
lower enclosure portion 300. The bosses of the upper enclosure portion 600 
allow the lower enclosure portion 600 to both cool and apply the 
appropriate level of force to the secondary electronic components located 
on the pc board 510 in a similar manner to the bosses 342 of the lower 
enclosure 300 as previously described. 
A pair of bolster plates, not shown, may fit within the openings in the 
lower enclosure portion 600. The bolster plates may be substantially 
identical to the bolster plate 400 previously described. The pair of 
bolster plates may be connected, e.g., by screws or bolts to the pair of 
cooling devices 550, 560 in an identical fashion to that previously 
described with respect to the bolster plate 400 and cooling device 250. In 
this manner, the cooling devices 550, 560 are able to cool and apply the 
appropriate level of force to the primary electronic components 512 in a 
similar manner to that previously described with respect to the cooling 
device 250 and the primary component 12. 
Other than the differences detailed above, the enclosure of FIG. 14 may be 
constructed and assembled in an identical fashion to the enclosure of 
FIGS. 1-13 as previously described. As can be appreciated from the 
foregoing description, the enclosure of FIG. 14 provides containment of 
electromagnetic energy generated by and for cooling of two primary and a 
plurality of secondary integrated circuit devices. It is to be understood, 
of course, that the enclosure described could also be adapted to contain 
and cool a greater number than two primary electronic components. 
While an illustrative and presently preferred embodiment of the invention 
has been described in detail herein, it is to be understood that the 
inventive concepts may be otherwise variously embodied and employed and 
that the appended claims are intended to be construed to include such 
variations except insofar as limited by the prior art.