Electronic device packaging arrangement

The subject electronic device packaging arrangement is designed to enhance heat transfer from an electronic device to the printed circuit board to which it is attached. This is accomplished by employing a thermally conductive base having a depression in the top thereof into which the electronic device is placed and bonded. The base has a protuberance in the bottom thereof corresponding to the depression in the top, which protuberance is attached to the associated printed circuit board. The protuberance on the base is formed to be in contact with the printed circuit board surface to provide thermal dissipation into the board by conduction processes. Continuous or segmented conductors are bonded both to the electronic device and to the base. These conductors are bent over the edge of the base to the bottom of the base where they align with corresponding contact points on the printed circuit board.

TECHNICAL FIELD 
This invention relates to electronic device packaging arrangements and, in 
particular, to a thermally improved base arrangement. 
BACKGROUND ART 
There have been numerous prior art electronic device packaging arrangements 
employing improved thermal dissipation apparatus. These prior art 
packaging arrangements include U.S. Pat. No. 4,037,270 issued July 19, 
1977 to G. L. Ahmann et al. The Ahmann patent teaches an electronic device 
packaging arrangement which provides improved thermal performance by 
securing the electronic device to a thermal dissipation pad which is, in 
turn, secured to a conduit through which a coolant is circulated. The 
disadvantage of this arrangement is that the thermal dissipation apparatus 
significantly raises the surface of the electronic device above the 
surrounding printed circuit board. As a result of this, all connections 
from the electronic device to the printed circuit board must be 
implemented by either free-standing conductors or connections through the 
electronic device itself to the printed circuit board. The free-standing 
conductor arrangement requires a large amount of printed circuit board 
area to implement and the free-standing conductors are also subject to 
mechanical stress which reduces their reliability. The through-the-device 
conductor arrangement eliminates these problems but is itself a very 
costly interconnection method to implement. 
DISCLOSURE OF THE INVENTION 
The foregoing problem is solved and technical advance achieved by an 
arrangement which employs a thermally conductive base having a depression 
in the top thereof into which the electronic device is placed and bonded. 
The base has a protuberance in the bottom thereof corresponding to the 
depression in the top, which protuberance is attached to the associated 
printed circuit board. The protuberance on the base is formed to be in 
contact with the printed circuit board surface to provide thermal 
dissipation to the board by conduction processes. Electrical conductors 
are bonded both to the device and to the base using an insulating material 
if the base is conductive, and any material if the base is of insulating 
material. These conductors are bent over the edge of the base and may be 
attached to the bottom of the base where they align with corresponding 
contact points on the printed circuit board. 
Thus, this thermally conductive base arrangement eliminates the need for 
free-standing conductors or costly interconnection methods while providing 
excellent thermal characteristics.

DETAILED DESCRIPTION 
FIG. 1 illustrates the electronic device packaging arrangement of my 
invention which employs a thermally conductive base. Base 101 is 
fabricated from a thermally conductive material such as aluminum and 
contains a depression in the top thereof. This depression is of sufficient 
size and depth such that an electronic device 100 may be placed therein 
and the top surface of electronic device 100 will be approximately the 
same level as the top surface of the outer rim of base 101. Assembly of 
this arrangement is implemented by placing electronic device 100 in the 
depression of base 101 and bonding electronic device 100 in well-known 
fashion to thermally conductive base 101. Continuous or segmented 
conductors 102 are joined in well-known fashion both to electronic device 
100 and, using an adhesive material 103, to base 101. 
Peripheral leads 102 extend around the edge of base 101 to the bottom 
surface thereof as shown in FIG. 1. These leads 102 are arranged such that 
they align with interconnection pads 109 on printed wiring board 110 and 
are joined thereto using conventional means. Base 101 is specifically 
formed to be in contact with printed wiring board 110 to provide thermal 
dissipation into and through printed wiring board 110 substantially by 
conduction processes. As shown in FIG. 1, a compliant material 111, such 
as a thermally conductive gel or a modified flux, can also be used at the 
interface of base 101 and printed circuit board 110 to enhance the heat 
transfer to printed circuit board 110. The use of a metal core printed 
circuit board 110 would further enhance the heat transfer over a 
conventional printed circuit board. An encapsulating material 104 is 
provided to cover electronic device 100 for electronic protection. 
This entire assembly is further covered by some cap or cover arrangement 
such as cap 106. Cap 106 is comprised of some suitable plastic material 
which can also be used to encapsulate an attendant discrete device. For 
example, capacitor 105 can be molded into cap 106 with capacitor leads 107 
extending to the periphery of the cap. Cap 106 is used to cover the entire 
assembly and is held in place by and also forms an electronic connection 
with leads 108 which are manufactured as an integral part of the lead 
frame of base 101, thereby establishing an electronic connection from 
leads 108 on base 101 to capacitor 105. Cap 106 may be thermally or 
adhesively bonded to base 101 in order to provide further mechanical and 
environmental integrity. 
While a specific embodiment of the invention has been disclosed, variations 
in structural detail within the scope of the appended claims are possible 
and are contemplated. There is no intention of limitation to what is 
contained in the abstract or the exact disclosure as herein presented. The 
above-described arrangements are only illustrative of the application of 
the principles of my invention, and other arrangements may be devised by 
those skilled in the art without departing from the spirit or the scope of 
my invention.