Electrical interconnect assemblies and methods

Details Electrical interconnect assemblies and methods Electrical interconnect assemblies and methods

1998-07-13

2004-03-16

Abrams, Neil (Department: 2839)

Electrical connectors

Preformed panel circuit arrangement, e.g., pcb, icm, dip,...

With provision to conduct electricity from panel circuit to...

C324S754090, C439S948000

Reexamination Certificate

active

06705876

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to interconnect assemblies and methods for making and using interconnections and more particularly to interconnect assemblies for making electrical contact with contact elements on a semiconductor integrated circuit in either a temporary or permanent manner. More particularly, the present invention relates to techniques and assemblies for making interconnections to semiconductor devices to perform test and/or burn-in procedures on the semiconductor devices or to make permanent interconnections to the semiconductor devices.
BACKGROUND OF THE INVENTION
There are numerous interconnect assemblies and methods for making and using these assemblies in the prior art. For example, it is usually desirable to test the plurality of dies on a semiconductor wafer to determine which dies are good prior to packaging them and preferably prior to their being singulated from the wafer. To this end, a wafer tester or prober may be advantageously employed to make a plurality of discrete pressure connections to a like plurality of discrete contact elements (e.g. bonding pads) on the dies. In this manner, the semiconductor dies can be tested prior to singulating the dies from the wafer. The testing is designed to determine whether the dies are non-functional (“bad”).
A conventional component of a wafer tester or prober is a probe card to which a plurality of probe elements are connected. The tips of the probe elements or contact elements effect the pressure connections to the respective bonding pads of the semiconductor dies.
FIG. 1
shows an interconnect assembly
500
which is an example of a probe card in the prior art. The probe pins or contact elements
524
make connections to bonding pads
526
on the semiconductor wafer
508
. The probe card assembly includes several components which are assembled together, including the probe card
502
, the interposer
504
, and the space transformer
506
. The probe card
502
is typically a printed circuit board which includes circuit traces to various electrical components which are used in performing the electrical tests of the semiconductor die being probed. Contact elements
510
on the probe card
502
make contact with the bonding pads
526
through a series of intervening layers which include the interposer
504
and the space transformer
506
as shown in FIG.
1
. The interposer
504
provides for a resilient, springlike positioning in the vertical or z direction in order to provide adequate contact for all contact elements at the bonding pads regardless of the length of the contact elements used on the intervening layers, such as the contact elements
524
which resemble springs. The space transformer
506
performs a pitch reduction and is also the substrate on which resilient contact elements are disposed. Further details concerning the probe card assembly
500
shown in
FIG. 1
may be found in PCT International Publication No. WO 96/38858.
FIG. 2A
shows in more detail an interposer assembly
300
having a substrate
302
on which resilient contact elements are attached, including contact elements
312
,
314
,
316
, and
318
. Contact elements
312
and
316
are electrically coupled from one side of interposer
300
to the other side by a through connect
304
A, and contact elements
314
and
318
are electrically coupled by a through connect
306
A. Examples of these resilient contact elements include any of a number of different spring type elements, including those described in the PCT International Publication No. WO 96/38858. When the interposer is used in an assembly such as the assembly
500
of
FIG. 1
, the resilient contact elements are flexed to a compressed state in which their vertical heights are reduced. This flexed state results in a force which drives the contact elements into their corresponding connection points, such as the bonding pads
526
.
FIGS. 2B and 2C
show an alternative interposer structure of the prior art. The interposer
300
A includes a substrate
302
A. Two resilient contact elements
312
A and
314
A are attached to one surface of the substrate
302
A. The resilient contact elements of the bottom portion of the substrate
302
A are not shown in this figure. The resilient contact elements on the upper surface of the substrate
302
A are protected by a channel structure
302
B which surrounds the resilient contact elements
312
A and
314
A. This can be seen from the top view of the interposer
300
which is shown in FIG.
2
C. The channel
302
B protects the resilient contact elements within the channel but is not designed to contact another substrate, and the channel
302
C protects resilient contact elements
314
B but is not designed to contact another substrate.
FIG. 3A
shows another example of an interposer of the prior art. The substrate
334
is placed over the interconnection elements
332
so that the interconnection elements
332
extend through the holes
336
. The interconnection elements
322
are loosely held within the substrate by a suitable material
338
, such as an elastomer which fills the holes
336
and which extends from the top and the bottom surfaces of the support substrate.
FIG. 3B
illustrates another interposer structure of the prior art in which the interconnection element within the hole
336
is attached to (e.g. by soldering) the middle portions of the holes
366
in the substrate
364
.
FIG. 4
illustrates another interconnect assembly of the prior art. This interconnect assembly is sometimes referred to as a cinch connector
400
. As shown in
FIG. 4
, two contact elements
406
and
407
are disposed on a substrate
401
in order to make contact with two other contact elements
408
and
409
which are disposed on another substrate
402
. The intermediate layer
403
includes holes
404
and
405
. The hole
404
is positioned between the contact elements
407
and
408
, and the hole
405
is positioned between the contact elements
407
and
409
. Each hole includes a resilient material which is used to make contact between its respective contact elements as shown in FIG.
4
. When the substrates
401
and
402
are pressed together, the contact elements or pads
406
and
408
move toward each other as do the contact elements
407
and
409
. The movement is stopped when each element comes into mechanical contact with the intermediate layer
403
, and electrical contact is established by the respective conductive spring which is disposed between the two contact elements.
As can be seen from the foregoing discussion, the use of resilient contact elements to make contacts to bonding pads or to other contact elements allows for tolerance in the vertical or z direction such that most if not all contact elements will be able to make contact even if their lengths vary slightly. However, this tolerance sometimes leads to the destruction of resilient contact elements as they are compressed too much in the vertical direction. While the assemblies shown in
FIGS. 2B and 2C
and in
FIG. 3A
may tend to protect resilient contact elements, they do not and are not intended to define a position in which all contact elements should have made contact vertically. The cinch connector of
FIG. 4
does tend to protect the resilient contact elements by preventing the substrates
401
and
402
from coming too close together. However, this assembly is relatively complicated due to the requirement of having, in a separate layer, a plurality of holes each of which includes and supports a spring.
Thus it is desirable to provide an improved interconnect assembly which may take advantage of the features of a resilient contact element without having too much tolerance in the z direction which could result in the overflexing or destruction of the resilient contact elements. This is particularly important for interconnection over large mating areas (as in semiconductor wafers), where tolerance issues make controlled deflection of interconnect elements difficult.
SUMMARY OF THE INVENTION
The present invention provides a plurality of inte

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