Package and connector receptacle

A connector assembly for connection to a computer backpanel or the like includes a leadless integrated circuit package and a connector receptacle for receiving the leadless package. The leadless package has two insulating layers and outwardly extending conductors formed on each of the two layers. The insulating layers have contact coupling edges, with the contact coupling edge of one layer extending outwardly of the contact coupling edge of the other layer. Rows of contacts in the receptacle make electrical contact with the conductors on the leadless package at the contact coupling edges. In a second embodiment, the connector assembly includes a leadless integrated circuit package having three insulating layers and outwardly extending conductors formed on each of the three layers.

BACKGROUND OF THE INVENTION 
The present invention relates to circuit packages and, more particularly, 
to leadless integrated circuit packages for supporting integrated circuit 
chips and connector receptacles for receiving such packages. 
Leadless integrated circuit packages are commonly used for mounting 
integrated circuits on printed circuit boards, computer backpanels, and 
the like, and have significant advantages over conventional dual in-line 
packages (DIP's) and single in-line packages (SIP's) in the manufacture of 
large electronic systems, such as computers. If, during the assembly of 
integrated circuits on a computer backpanel, there is discovered a defect 
in one of the integrated circuits, the leadless package having the 
defective integrated circuit is simply removed from its receptacle and 
replaced with a new package. There is thereby eliminated the problem of 
removing packages having soldered leads or pins, and the potential for 
bending or breaking such pins when removed. 
As is the case with any integrated circuit package, whether leadless or 
not, there is a practical limitation on the number of external connections 
that can be made to the package and chip, such limitation largely 
depending on the physical dimensions of the package. A leadless package 
typically has an insulating substrate or layer and a plurality or set of 
conductors on the layer extending between connector coupling edges about 
the periphery of the layer and a center or central location of the package 
where the integrated circuit chip is supported. These conductors provide 
electrical connections to the chip, but must be limited in number since 
each conductor requires a certain amount of surface area on the layer. 
Advances in integrated circuit technology have resulted in increased 
circuit densities and, in turn, increased numbers of circuit functions 
that can be provided on a single integrated circuit chip. However, such 
increases in the number of functions often require additional external 
electrical connections to the chip. In the past, the only apparent way in 
which the number of external connections could be increased was generally 
to increase the size or surface area of the package so that more 
conductors would be provided between the connector coupling edges of the 
insulating layer and the integrated circuit layer. Increasing the size of 
the package, however, also increases the amount of area required for each 
package on a circuit board or backpanel, and thus eliminates some of the 
space savings achieved by the increased circuit density of the chip 
itself. 
SUMMARY OF THE INVENTION 
There is provided, in accordance with the present invention, a leadless 
integrated circuit package that, in comparison to prior packages, has an 
increased number of external electrical connections to an integrated 
circuit chip supported in the package, without a significant increase in 
the surface area of the package. 
More particularly, there is provided, in accordance with the present 
invention, a leadless package for mounting an integrated circuit chip, the 
leadless package having a first plurality of substantially coplanar 
conductors electrically connected to and projecting outwardly from the 
chip. A second plurality of coplanar conductors are also electrically 
connected to and project outwardly from the chip. The second plurality of 
conductors each lie in a plane spaced from the plane of the first 
plurality of conductors in a direction that is substantially transverse to 
the direction in which the conductors extend outwardly from the chip. 
The first plurality of conductors are formed on a first insulating layer 
and the second plurality of conductors are formed on a second insulating 
layer. The first layer overlies the second layer and has a contact 
coupling edge that overhangs or is spaced outwardly from an adjacent 
contact coupling edge of the second layer. 
An electrical connector receptacle is provided for receiving the package, 
the receptacle having rows of contacts spaced to make electrical contact 
with the conductors on the contact coupling edges of the two layers of the 
package. Each contact in the receptacle couples with one conductor at the 
contact coupling edge of one of the layers. 
In one described embodiment, the two insulating layers include a first, 
upper layer and a second, lower layer. The upper layer has four contact 
coupling edges projecting or spaced outwardly of four contact coupling 
edges of the lower layer. Conductors on each of the upper and lower layers 
extend between the contact coupling edges and the integrated circuit chip 
at a center open portion of the package. The connector receptacle for 
receiving the package includes an outer row of contacts and an inner row 
of contacts along upper and lower edges, respectively, of four side walls 
within the receptacle. The contacts in the outer rows electrically contact 
the conductors at the contact coupling edges of the upper layer of the 
package, and the contacts in the inner rows electrically contact 
conductors at the contact coupling edge of the lower layer of the package. 
It is, therefore, an object of the present invention to provide an improved 
circuit package. 
It is another object of the present invention to provide an integrated 
circuit package that requires a minimum amount of surface area when 
electrically connected at a printed circuit board or computer backpanel. 
It is another object of the present invention to provide an improved 
leadless integrated circuit package having a large number of conductors 
for providing external electrical connections to an integrated circuit 
chip supported in the package. 
It is still another object of the present invention to provide a leadless 
integrated circuit package and to provide an electrical connector 
receptacle for receiving the package, where a large number of electrical 
connections are made to the integrated circuit chip supported in the 
package. 
These and other objects of the present invention will become more apparent 
when taken in conjunction with the following description and the attached 
drawings.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Turning now to the drawings, there is shown in FIG. 1 a connector assembly 
10 for electrically connecting an integrated circuit chip 12 to a computer 
backpanel 14. The integrated circuit chip 12 is supported or mounted, as 
shown in phantom in FIG. 1, on the underside of a leadless integrated 
circuit package 16. The package 16 can be removably inserted into a 
connected receptacle 20 and is held in place in the receptacle 20 by a 
cover plate 22. The cover plate 22 is secured to the receptacle 20 by 
conventional means, such as the illustrated screws 24 that pass through 
holes 26 in the cover plates 22 and are threadedly received in aligned 
holes 25 at the four corners of a housing 30 of the receptacle 20. 
Alternatively, but not shown in the drawings, the cover plate 26 could, as 
conventional, be hinged to the housing 30 along one side thereof, and have 
a latch or clip for releasably securing the cover plate 26 to the opposite 
side of the housing. The actual manner in which the cover plate 26 is 
secured to the housing 20 is unimportant for purposes of the present 
invention. 
As seen in FIG. 1, the housing 30 of the receptacle 20 has four side walls 
32 and a bottom wall 34 that define an upwardly and outwardly opening 
chamber 36 into which the leadless package 16 is placed. The side walls 32 
include, within the housing 30 and around the chamber 36, an upper ledge 
37 and a lower ledge 38. An outer row of resilient electrical contacts 40 
(only two of which are shown in FIG. 1) extend through apertures 41 into 
the chamber 36 at the upper ledge 37 along each of the side walls 32. 
Similarly, an inner row of resilient electrical contacts 42 (only two of 
which are shown in FIG. 1) extend through apertures 43 into the chamber 36 
at the lower ledge 38 along each of the side walls 32. 
As can be seen in the drawings, the contacts 40 are spaced both upwardly 
and outwardly from the contacts 42. The contacts 40 are electrically 
connected to outer rows of pins 48 projecting downwardly from the bottom 
of housing 30, and the contacts 42 are electrically connected to inner 
rows of pins 50, spaced inwardly from the outer rows of pins 48 and also 
projecting downwardly from the bottom of the housing 30. The pins 48 and 
50 are received in apertures 54 in the backpanel 14 for making electrical 
connections with circuits or conductors (not shown) at the backpanel. 
As will be described in greater detail later, when the connector assembly 
10 is fully assembled, the leadless package 16 is held firmly between the 
cover plate 22 and the rows of contacts 40 and 42 in the housing chamber 
36. Each of the contacts 40 and 42 will provide an electrical connection 
between one of the pins 48 and 50 and the leadless package 16. 
Referring now to FIGS. 2 and 3, there is shown in greater detail the 
leadless integrated circuit package 16. As can be seen, the leadless 
package 16 is comprised of an upper insulating layer 60 and a lower 
insulating layer 62. The lower layer 62 is open at its center and defines, 
with the underside of the top layer 60, a central open portion or pocket 
66 for receiving the integrated circuit chip 12. The integrated circuit 
chip 12 may be fixed, such as by adhesive, to the underside of the top 
layer 60 at the pocket 66. 
A set or plurality of coplanar conductors 68 (illustrated partially in FIG. 
3) extend outwardly along the underside of the upper layer 60 from the 
pocket 66 to contact touching or coupling edges 70 located about the 
periphery of the upper layer. Likewise, a set or plurality of coplanar 
conductors 72 (illustrated partially in FIG. 3) extend outwardly along the 
underside of the lower layer 62 from the pocket 66 to contact touching or 
coupling edges 74 located about the periphery of the lower layer. The 
conductors 68 terminate at pads 76 along the contact coupling edges 70 of 
the upper layer 60 and the conductors 72 terminate at pads 78 along the 
contact coupling edges 74 of the lower layer 62. The conductors 68 and 72 
are electrically connected at the pocket 66 in a conventional fashion, 
such as by wires 80, to the integrated circuit chip 12. 
Although, for purposes of simplifying the drawings, the conductors 68 and 
72 are shown in FIG. 3 as extending from generally only one side of the 
pocket 66 to the contact coupling edges, in actual practice the conductors 
will extend from each side of the pocket 66 to all four edges along the 
periphery of each of the layers 60 and 62. 
The conductors 68 and the conductors 72 lie in planes that are essentially 
separated by the thickness of the lower insulating layer 62. As will 
become apparent, the separation of the conductors 68 and the conductors 72 
in a direction which is generally perpendicular or transverse to the 
direction in which the conductors extend outwardly permits an increase in 
the number of external connections to the integrated circuit chip 12, 
without a significant increase in the surface area of the leadless package 
16. 
As can be seen in FIGS. 2 and 3, the upper layer 60 is larger in surface 
area than the lower layer 62 so that the contact coupling edges 70 of the 
layer 60 extend beyond and are spaced outwardly from the contact coupling 
edge 74 of the layer 62. The pads 76 of conductors 68 are exposed at the 
edges 70 so that they each couple with or touch one of the previously 
mentioned contacts 40 in the connector receptacle 20. The pads 78 of the 
conductors 72 are spaced inwardly, as well as downwardly from the pads 76, 
so that they each couple with or touch one of the previously mentioned 
contacts 42 in the receptacle 20. 
The conductors 68 and 72 can be formed on the layers 60 and 62 using a 
conventional process, such as photoetching. Once the conductors 68 and 72 
have been so formed, the layer 62 can be affixed to the layer 60 by, for 
example, a suitable adhesive or the like. 
As illustrated in FIG. 4, when the leadless package 16 is secured in the 
connector receptacle 20, with the screws 24 holding the cover plate 22 
firmly at the top of housing 30 of connector receptacle 20, the leadless 
package 16 is urged against the contacts 40 and 42 along the ledges 37 and 
38 on the side walls of housing 30. The contacts 40 and 42 will 
resiliently deform as needed to accommodate the package 16, with each 
contact in firm physical and electrical contact with one of the pads 76 
and 78 on the package 16. An electrical path is thereby established 
between each of the pins 48 and 50 and the circuitry on the integrated 
circuit chip 12. 
It should be apparent from the foregoing description that the number of 
external electrical connections made to the integrated circuit chip 12 in 
the leadless package 16 is significantly greater than the number of 
external electrical connections in prior leadless packages by virtue of 
having both the plurality of conductors 68 and the plurality of conductors 
72, each plurality of conductors extending outwardly from integrated 
circuit chip 12 so that each conductor makes electrical contact with one 
of the contacts 40 and 42 in the connector receptacle 20. Since the 
conductors 68 on layer 60 lie in a plane that is spaced transversely from 
the plane in which conductors 72 on layer 62 lie, the amount of surface 
area that the leadless package 16 occupies is not significantly greater 
than the surface are of prior packages that have only one plurality or set 
of conductors. 
In FIG. 5, there is shown a connector assembly 10a illustrating an 
alternative embodiment of the present invention. In order to further 
increase the number of electrical connections made to an integrated 
circuit chip (not shown) that is mounted in a leadless integrated circuit 
package 16a, the package 16a of the connector assembly 10a is shown as 
having a set of coplanar conductors 68a, a set of coplanar conductors 72a, 
and a set of coplanar conductors 90a. The conductors 68a each are formed 
on the underside of an upper insulating layer 60a, each extend outwardly 
from the center of layer 60a, and each terminate at a pad 76a at a contact 
coupling edge 70a of the layer 60a. The conductors 72a each are formed on 
the underside of a middle insulating layer 62a, each extend outwardly from 
the center of layer 62a, and each terminate at a pad 78a at a contact 
coupling edge 74a of the layer 62a. In the same fashion, conductors 90a 
are each formed on the underside of a lower insulating layer 92a, each 
extend outwardly from the center of layer 92a, and each terminate at a pad 
94a at a contact coupling edge 96a of the layer 92a. 
The contact coupling edge 96a on layer 92a is spaced inwardly and 
downwardly of contact coupling edge 74a and layer 62a. Likewise, contact 
coupling edge 74a on layer 62a is spaced downwardly and inwardly of 
contact coupling edge 70a on layer 60a. As a result, when the leadless 
package 16a is secured in a connector receptacle 20a, the pads 76a, 78a 
and 94a make firm physical and electrical contact with contacts 40a, 42a 
and 98a within the receptacle 20a. The contacts 40a, 42a and 98a are 
electrically connected to pins 48a, 50a and 100a, respectively, that 
project from the bottom of the receptacle 20a. 
It should be apparent, of course, that although the embodiment of FIG. 5 
shows three sets of coplanar conductors extending outwardly from the 
integrated circuit chip at the center of the leadless package 16a, 
additional sets of conductors and insulating layers could be provided to 
even further increase the number of external electrical connections to the 
integrated circuit chip. 
Although the presently preferred embodiments of the present invention have 
been described, it will be understood that within the purview of this 
invention various changes may be made within the scope of the appended 
claims.