U.S. patent number RE37,368 [Application Number 09/064,536] was granted by the patent office on 2001-09-18 for high density, high bandwidth, coaxial cable, flexible circuit and circuit board connection assembly.
This patent grant is currently assigned to Medallion Technology, LLC. Invention is credited to Steven E. Garcia, Jon M. Huppenthal.
United States Patent |
RE37,368 |
Huppenthal , et al. |
September 18, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
High density, high bandwidth, coaxial cable, flexible circuit and
circuit board connection assembly
Abstract
A connection assembly includes a coaxial cable to microstrip
flexible circuit connector and a mating microstrip flex circuit to
electronic circuit connector. The coaxial cable to microstrip flex
circuit connector comprises a portion which is mechanically
attached to the coaxial cable and a portion which is mechanically
attached to the microstrip flex circuit. The coaxial cable
attachment portion includes a first electrical connector
electrically connected to the center conductor and a second
electrical connector electrically connected to the shielding
conductor of each coaxial cable. The microstrip flex circuit
attachment portion includes a third electrical connector
electrically connected to each trace and a fourth connector
electrically connected to the ground plane conductor. The flex
circuit to electrical circuit connector comprises a plurality of
unsupported extensions of a trace or the ground plane conductor.
The extensions are electrically connected to connection pads of a
printed circuit board of an electronic circuit by a surface
connection, and can be bent to opposite sides of the electronic
circuit to reach connection pads on a printed circuit board.
Inventors: |
Huppenthal; Jon M. (Colorado
Springs, CO), Garcia; Steven E. (League City, TX) |
Assignee: |
Medallion Technology, LLC
(Houston, TX)
|
Family
ID: |
23343539 |
Appl.
No.: |
09/064,536 |
Filed: |
April 22, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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910716 |
Aug 13, 1997 |
Re36845 |
|
|
Reissue of: |
342850 |
Nov 21, 1994 |
05509827 |
Apr 23, 1996 |
|
Reissue of: |
910716 |
Aug 13, 1997 |
01036845 |
Aug 29, 2000 |
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Current U.S.
Class: |
174/74R; 174/78;
333/260; 439/581; 439/638 |
Current CPC
Class: |
H01R
12/775 (20130101); H01R 13/6585 (20130101); H01R
24/50 (20130101); H01R 12/594 (20130101); H01R
12/79 (20130101); H01R 24/52 (20130101); H01R
12/598 (20130101); H01R 12/81 (20130101); H01R
2103/00 (20130101) |
Current International
Class: |
H01R
13/646 (20060101); H01R 12/24 (20060101); H01R
12/00 (20060101); H01R 12/16 (20060101); H01R
13/00 (20060101); H02G 015/02 (); H01R 009/05 ();
H01R 009/07 () |
Field of
Search: |
;174/135,78,88B,12R,84C,88R,88C ;439/579,497,581 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Ken Gilleo (Editor), Handbook of Flexible Circuits, pp. 42-68
(authored by Joe Fjelstand and Ken Gilleo), 1992. .
Agard et al., Coaxial Cable To Printed Circuit Board Connector, IBM
Tech. Discl. Bulletin, vol. 13, No. 6, p. 1595, Nov. 1970..
|
Primary Examiner: Kincaid; Kristine
Assistant Examiner: Mayo, III; William H
Attorney, Agent or Firm: Ley; John R. Lindsay; L. Jon
Fulghum; Roger J.
Parent Case Text
.Iadd.This reissue application is a division of and claims the
benefit under 35 U.S.C. 120 of a pending prior reissue application
having application Ser. No. 08/910,716, now U.S. Pat. No. Re.
36,845, which is a reissue of a parent application having the Ser.
No. 08/342,850, now U.S. Pat. No. 5,509,827. .Iaddend.
Claims
The invention claimed: .[.
1. A connection assembly including a coaxial cable to microstrip
flex circuit connector which interconnects a center conductor and a
shielding conductor of a coaxial cable with a trace and a ground
plane conductor of a microstrip flex circuit respectively, said
coaxial cable to microstrip flex circuit connector comprising:
a coaxial cable attachment portion mechanically attached to a
plurality of coaxial cables, the coaxial cable attachment portion
including a plurality of first electrical connectors, each of which
is separately electrically connected to the center conductor of the
coaxial cable and a plurality of second electrical connectors, each
of which is electrically connected to at least one shielding
conductor of the plurality of coaxial cables;
a microstrip flex circuit attachment portion mechanically attached
to a microstrip flex circuit having a plurality of traces, the
microstrip flex circuit attachment portion including a plurality of
third electrical connectors, each of which is separately
electrically connected to a trace, and a plurality of fourth
connectors, each of which is commonly connected to the ground plane
conductor; and wherein:
the coaxial cable attachment portion and the microstrip flex
circuit attachment portion mate with one another and when mated
separately connect the first and third electrical connectors and
the second and fourth electrical connectors..]. .[.
2. A connection assembly as defined in claims 1 wherein:
the coaxial cable attachment portion includes a body which retains
the first and second electrical connectors in a predetermined
pattern;
the microstrip flex circuit attachment portion includes a body
which retains the third and fourth electrical connectors in a
predetermined pattern;
the predetermined pattern of the electrical connectors in the body
of the coaxial attachment portion corresponds with the
predetermined pattern of the electrical connectors in the body of
the microstrip flex circuit attachment portion; and
the predetermined patterns of electrical connectors in the bodies
of the coaxial attachment portion and the microstrip flex circuit
attachment portion allowing contact of the first electrical
connectors with the third electrical connectors and allowing
contact of the second electrical connectors with the fourth
electrical connectors when the attachment portions mate
together..]. .[.
3. A connection assembly as defined in claim 2 wherein:
the first and third electrical connectors are each of a same first
structure;
the second and fourth electrical connectors are each of a same
second structure; and
the first and second structures are adapted to connect with one
another..]. .[.
4. A connection assembly as defined in claim 3 wherein:
one of the first or second structure is an insert; and
the other one of the first or second structure is a socket..].
.[.
5. A connection assembly as defined in claim 2 wherein:
the center conductors of a first plurality of coaxial cables are
each connected to on first electrical connector; and
the shielding conductors of the first plurality of coaxial cables
are commonly connected to a second electrical connector located in
the predetermined pattern in adjacency with the first electrical
connectors to which the center conductors of the first plurality of
coaxial cables are connected..]. .[.
6. A connection assembly as defined in claim 5 wherein said coaxial
cable to microstrip flex circuit connector further comprises:
a grounding clip connected to the coaxial cable attachment portion
and to the shielding conductors of the first plurality of coaxial
cables, the grounding clip further including a projection portion
connected to a second electrical connector..]. .[.
7. A connection assembly as defined in claim 6 wherein:
the predetermined pattern of electrical connectors is at least one
row in the each attachment portion;
the first plurality of coaxial cables is two coaxial cables;
the grounding clip further includes two wing portions, each wing
portion extending to and connecting with one shielding conductor of
each of the two coaxial cables of the first plurality; and
the grounding clip further includes a projecting portion connecting
to a second electrical connector..]. .[.
8. A connection assembly as defined in claim 7 wherein:
the predetermined pattern of electrical connectors is at least one
row in each attachment portion;
the first electrical connectors are located in the first and third
positions a sequence of three electrical connectors in the row;
the second electrical connector is located in the second position
in the sequence of the three electrical connectors in the row;
the grounding clip is generally T-shaped with the wing portions
extending outward from the projecting portion of the grounding
clip;
the wing portions of the grounding clip extend to and connect with
the shielding conductors of the coaxial cables which have center
conductors connected to the first electrical connectors in the
first and third positions in the sequence of the three electrical
connectors in the row; and
the projecting portion of the grounding clip extends to and
connects with the second electrical connector in the second
position in the sequence of the three electrical connectors in the
row..]. .[.
9. A connection assembly as defined in claim 8 wherein:
the wing portions of the grounding clip are connected to the
shielding conductors of the coaxial cables by bending the wing
portions around a portion of the shielding connectors..]. .[.
10. A connection assembly as defined in claim 9 wherein:
the first and second electrical connectors are each sockets;
the sockets are retained in holes formed in the predetermined
pattern in the body of the coaxial cable attachment portion with
each socket projecting from a mating surface of the body of the
coaxial cable attachment portion; and
the third and fourth electrical connectors are each an insert;
the inserts are positioned in holes in the body of the microstrip
flex circuit attachment portion with each insert recessed from a
mating surface of the body of the microstrip flex circuit
attachment portion; and
the inserts contact the sockets when the attachment portions
connect with one another..]. .[.
11. A connection assembly as defined in claim 2 wherein:
each of a first plurality of traces of the microstrip flex circuit
is connected to a third electrical connector; and
each of the fourth electrical connectors is commonly connected to
the ground plane conductor of the microstrip flex circuit..].
.[.
12. A connection assembly as defined in claim 11 wherein:
each of the third and fourth electrical connectors includes a
contact end extending from the body of the microstrip flex circuit
attachment portion; and
the contact ends of the third electrical connectors contact traces
of the microstrip flex circuit..]. .[.
13. A connection assembly as defined in claim 12 wherein:
the microstrip flex circuit includes ground trace pads formed
between traces, and electrical connections between the ground trace
pads and the ground plane conductor; and
the contact ends of the fourth electrical connectors contact and
are connected to the ground trace pads of the microstrip flex
circuit..]. .[.
14. A connection assembly as defined in claim 13 wherein:
the ground trace pads are connected to the ground plane conductor
by a plated through hole..]. .[.
15. A connection assembly as defined in claim 12 wherein:
the microstrip flex circuit includes a layer of insulation adjacent
to the ground plane conductor and exposed areas of the ground plane
conductor surrounded by the insulation; and
the contact ends of the fourth electrical connectors contact the
exposed areas of the ground plane conductor of the microstrip flex
circuit..]. .[.
16. A connection assembly as defined in claim 12 wherein:
the predetermined pattern of electrical connectors is at least one
row in the microstrip flex circuit attachment portion;
the third electrical connectors are located in the first and third
positions in a sequence of three electrical connectors in the
row;
a fourth electrical connector is located in the second position of
the sequence of the three electrical connectors in the row;
two traces are located spaced apart on the microstrip flex circuit
to connect the contact end of each third electrical connector to
each of the two traces; and
the contact end of each fourth electrical connector is connected to
the ground plane conductor at a location between the two traces to
which the contact ends of third electrical connectors are
attached..]. .[.
17. A connection assembly as defined in claim 16 wherein:
the predetermined pattern of electrical connectors is two parallel
rows in the microstrip flex circuit attachment portion, the two
rows are spaced transversely apart; and
the microstrip flex circuit is positioned between the two rows with
the contact ends of the third and fourth electrical connectors
connected to the traces and ground plane conductor,
respectively..]. .[.
18. A connection assembly as defined in claim 17 wherein:
the microstrip flex circuit includes traces and ground trace pads
on opposite sides of the ground plane conductor and separated from
the ground plane conductor by a layer of insulation;
the third electrical connectors are located in the first and third
positions of the sequence of the three electrical connectors in
each of the two rows, each third electrical connector in one row is
directly opposite of a third electrical connector in the other
row:
a fourth electrical connector is located in the second position in
the sequence of the three electrical connectors in each row, the
fourth electrical connector of one row is directly opposite of the
fourth electrical connector in the other row;
the distance between the retaining ends of the electrical
conductors in the two rows is approximately equal to the distance
between the traces and ground trace pads on opposite sides of the
microstrip flex circuit; and
the traces and ground trace pads on opposite sides of the ground
plane conductor are connected to the contact ends of the third and
fourth electrical connectors..]. .[.
19. A connection assembly as defined in claim 18 wherein:
the first and second electrical connectors are each sockets;
the sockets are retained in holes formed in the predetermined
pattern in the body of the coaxial cable attachment portion with
each socket projecting from a mating surface of the body of the
coaxial cable attachment portion; and
the third and fourth electrical connectors are each an insert;
the inserts are positioned in holes in the body of the microstrip
flex circuit attachment portion located in a predetermined position
corresponding with the locations of the sockets, each insert is
recessed from a mating surface of the body of the microstrip flex
circuit attachment portion; and
the inserts contact the sockets when the attachment portions
connect with one another..]. .[.
20. A connection assembly as defined in claim 17 wherein:
the microstrip flex circuit includes traces located on opposite
sides of the ground plane conductor, a layer of insulation adjacent
to the ground plane conductor and exposed areas of the ground plane
conductor surrounded by the insulation;
the third electrical connectors are located in the first and third
positions of the sequence of the three electrical connectors in
each of the two rows, each third electrical connector in one row is
directly opposite of a third electrical connector in the other
row:
a fourth electrical connector is located in the second position in
the sequence of the three electrical connectors in each row, the
fourth electrical connector of one row is directly opposite of the
fourth electrical connector in the other row; and
the traces on opposite sides of the ground plane conductor and the
exposed areas of the ground plane conductor are connected to the
contact ends of the third and fourth electrical connectors..].
.[.
21. A connection assembly as defined in claim 20 wherein:
the first and second electrical connectors are each sockets;
the sockets are retained in holes formed in the predetermined
pattern in the body of the coaxial cable attachment portion with
each socket projecting from a mating surface of the body of the
coaxial cable attachment portion; and
the third and fourth electrical connectors are each an insert;
the inserts are positioned in holes in the body of the microstrip
flex circuit attachment portion located in a predetermined position
corresponding with the locations of the sockets, each insert is
recessed from a mating surface of the body of the microstrip flex
circuit attachment portion; and
the inserts contact the sockets when the attachment portions
connect with one another..]. .[.
22. A connection assembly including a microstrip flex circuit to
electrical circuit connector which interconnects a plurality of
traces and a ground plane conductor of the microstrip flex circuit
to connection pads formed on the electrical circuit, and a coaxial
cable to microstrip flex circuit connector which interconnects a
center conductor and a shielding conductor of a coaxial cable with
a trace and a ground plane conductor of a microstrip flex circuit
respectively, said coaxial cable to microstrip flex circuit
connector comprising:
a coaxial cable attachment portion mechanically attached to the
coaxial cable, the coaxial cable attachment portion including a
first electrical connector electrically connected to the center
conductor of the coaxial cable and a second electrical connector
electrically connected to the shielding conductor;
a microstrip flex circuit attachment portion mechanically attached
to the microstrip flex circuit, the microstrip flex circuit
attachment portion including a third electrical connector
electrically connected to a trace and a fourth connector
electrically connected to the ground plane conductor; wherein: the
coaxial cable attachment portion and the microstrip flex circuit
attachment portion mate with one another and when mated separately
connect the first and third electrical connectors and the second
and fourth electrical connectors; and said microstrip flex circuit
to electrical circuit connector comprising:
a plurality of unsupported extensions of the traces and the ground
plane conductor extending from the microstrip flex circuit; and
an electrical surface to surface connection of the extensions to
the connection pads on the electrical circuit..]. .[.
23. A connection assembly as defined in claim 22 wherein:
the microstrip flex circuit includes traces located on opposite
sides of the ground plane conductor, a layer of insulation adjacent
to the ground plane conductor and exposed areas of the ground plane
conductor surrounded by the insulation;
the electrical circuit includes a printed circuit board and the
connection pads are located on a side of the printed circuit board;
and
at least one extension is bent from one side to the other side of
the microstrip flex circuit to connect to a connection pad located
adjacent to the other side of the microstrip flex circuit..].
.[.
24. A connection assembly as defined in claim 23 wherein:
at least one extension from the ground plane conductor bent to
connect to a connection pad on the printed circuit board..].
.[.
25. A connection assembly as defined in claim 23 wherein said
microstrip flex circuit to circuit board connection further
includes a potting material connecting the microstrip flex circuit
to the printed circuit board..]..Iadd.
26. A coaxial cable grounding clip to connect an exposed shielding
conductor of a first coaxial cable and an exposed shielding
conductor of a second coaxial cable, comprising:
a first wing portion having a shape to contact the shielding
conductor of the first coaxial cable and to retain a portion of the
first coaxial cable to the first wing portion;
a second wing portion having a shape to contact the shielding
conductor of the second coaxial cable and to retain a portion of
the second coaxial cable to the second wing portion;
the first and second wing portions connecting together at a
connection point;
a projection portion connected to the first and second wing
portions at the connection point and extending longitudinally in
parallel alignment with the portions of the first and second
coaxial cables retained to the first and second wing portions,
respectively;
the first and second wing portions extending transversely from the
connection point, transversely relative to the projection portion
and transversely relative to the portions of the first and second
coaxial cables retained to the first and second wing portions,
respectively; and
the first and second wing portions retaining the first and second
coaxial cables in general parallel alignment with one another and
with the projection portion at the portions of the first and second
coaxial cables retained to the first and second wing portions,
respectively. .Iaddend..Iadd.
27. A coaxial cable grounding clip as defined in claim 26, wherein
each wing portion at least partially surrounds the exposed
shielding conductor of the portion of each coaxial cable retained
by each wing portion. .Iaddend..Iadd.
28. A coaxial cable grounding clip as defined in claim 27 wherein
each coaxial cable has a cover of a predetermined thickness which
is exterior to and which surrounds the shielding conductor, and
wherein:
each wing portion which partially surrounds the exposed shielding
conductor has a thickness that is generally the same as the
thickness of the cover of the coaxial cable. .Iaddend..Iadd.
29. A coaxial cable grounding clip as defined in claim 28, wherein
the wing portions and projection portion are each formed on a
conductive metal. .Iaddend..Iadd.
30. A coaxial cable grounding clip as defined in claim 29 wherein
the wing portions and projection portion are each formed of copper.
.Iaddend..Iadd.
31. A coaxial cable grounding clip as defined in claim 27, wherein
each coaxial cable has a cover of a predetermined thickness which
is exterior to and which surrounds the shielding conductor, and
wherein:
each wing portion which partially surrounds the exposed shielding
conductor electrically connects to the exposed shielding conductor
and has a thickness that is generally no greater than the thickness
of the cover of the coaxial cable to consume substantially no
greater space than does the cover at the retained portion of the
coaxial cable. .Iaddend..Iadd.
32. A coaxial cable grounding clip as defined in claim 27,
wherein:
the first and second wing portions retain the first and second
coaxial cables in transversely spaced apart relationship with each
other and with the projection portion; and
the projection portion and the first and second coaxial cables are
generally located in a linear transversely spaced apart
relationship. .Iaddend..Iadd.
33. A coaxial grounding clip as defined in claim 32, wherein each
coaxial cable has a center conductor surrounded by the shielding
conductor, and wherein the projection portion includes a distal end
upon which a mating surface is located; and the mating surface of
the distal end of the projection portion and the center conductors
of the first and second coaxial cables are located in a linear
transversely spaced apart relationship established by the position
of the first and second coaxial cables retained by the wing
portions. .Iaddend..Iadd.
34. A coaxial cable grounding clip as defined in claim 27, wherein
the first and second wing portions form a common ground electrical
connection of the first and second coaxial cables.
.Iaddend..Iadd.
35. A method of connecting a shielding conductor of each of a
plurality of coaxial cables to a common electrical reference with a
grounding clip having a plurality of wing portions extending from a
projection portion, each wing portion having a shaped segment to
contact the shielding conductor and to retain a portion of one of
the coaxial cables to the wing portion, the wing portions retaining
the coaxial cables in generally parallel alignment with one
another, the projection portion extending longitudinally in
parallel alignment with the portions of the coaxial cables retained
to the wing portions, said method comprising the steps of:
exposing a portion of the shielding conductor of each coaxial
cable;
correlating each coaxial cable with one of the wing portions;
and
for each correlated coaxial cable and wing portion:
contacting the exposed shielding conductor of the coaxial cables
with the shaped segment of the wing portion; and
retaining the coaxial cable at the shaped segment; and
orienting all of the coaxial cables retained to the wing portions
in generally parallel alignment with one another and with the
projection portion. .Iaddend..Iadd.
36. A method as defined in claim 35 further comprising the step
of:
retaining each coaxial cable to its correlated wing portion by
frictional contact of the shielding conductor with the shaped
segment. .Iaddend..Iadd.
37. A method as defined in claim 35, further comprising the step
of:
at least partially surrounding each shielding conductor with the
shaped segment of the correlated wing portion. .Iaddend..Iadd.
38. A method as defined in claim 35 wherein each coaxial cable has
a cover of predetermined thickness which is exterior to and which
surrounds the shielding conductor, said method further comprising
the steps of:
removing a portion of the cover of each coaxial cable to create the
exposed portion of the shielding conductor;
contacting each shaped segment with the exposed portion of the
shielding conductor at a location adjacent to the cover of the
correlated coaxial cable; and
confining each shaped segment to a space that was occupied by the
cover of each correlated coaxial cable before the exposed portion
was created. .Iaddend..Iadd.
39. A method as defined in claim 35 further comprising the step
of:
orienting the projection portion and the plurality of coaxial
cables connected to the grounding clip in a transversely spaced
apart and substantially linear parallel alignment with one another.
.Iaddend..Iadd.
40. A method as defined in claim 39, further comprising the step
of:
connecting the projection portion into an electrical connector.
.Iaddend..Iadd.
41. A method as defined in claim 40, wherein each coaxial cable has
a center conductor surrounded by the shielding conductor, further
comprising the step of:
connecting the center conductor of each coaxial cable into the
electrical connector to which the projection portion is connected.
.Iaddend..Iadd.
42. A grounding clip to connect to an exposed shielding conductor
of a coaxial cable, comprising:
a wing portion having a shape to contact the shielding conductor
and to retain a portion of the coaxial cable to the wing portion;
and
a projection portion connected to the wing portion and extending
longitudinally in parallel alignment with a portion of the coaxial
cable retained to the wing portion;
the wing portion extending transversely relative to the projection
portion and the portion of the coaxial cable retained to the wing
portion from a connection point where the wing portion connects to
the projection portion. .Iaddend..Iadd.
43. A grounding clip as defined in claim 42 wherein the projection
portion includes a distal end upon which a mating surface is
located. .Iaddend..Iadd.
44. A grounding clip as defined in claim 42, wherein:
the wing portion at least partially surrounds the exposed shielding
conductor of the portion of the coaxial cable retained by the wing
portion. .Iaddend..Iadd.
45. A grounding clip as defined in claim 44, wherein the coaxial
cable has a cover of a predetermined thickness which is exterior to
and which surrounds the shielding conductor, and wherein:
the wing portion which partially surrounds the exposed shielding
conductor has a thickness that is generally the same as the
thickness of the cover of the coaxial cable. .Iaddend.
Description
The present invention relates generally to interconnecting coaxial
cables, microstrip flexible circuits and electronic circuits, in a
manner which consumes a relatively small amount of space, which
does not materially degrade the frequency response or "bandwidth"
of the high frequency signals which are transmitted to and from the
electronic circuit, and which is convenient to manufacture and use.
More particularly, the invention relates to new and improved
connectors for interconnecting a relatively high number of coaxial
cables to traces of the flexible circuit, for interconnecting a
relatively large number of traces of a flexible circuit to the
electronic circuit, and for interconnecting a relatively large
number of coaxial cables.
BACKGROUND OF THE INVENTION
Transmitting very high frequency signals between physically
separated circuits can be particularly difficult, because the
higher frequency signals are susceptible to a variety of different
adverse influences that do not affect lower frequency signals to an
appreciable degree. In general, higher frequency signals carry more
information per unit of time. The amount of information per unit of
time is generally referred to as the "bandwidth" or information
carrying capability of the signal. If the quality of the signal is
degraded to the point where the informational characteristics of
the signal can not be detected or decoded accurately, the bandwidth
of the signal is reduced.
It is desirable to reduce or eliminate signal degradation as much
as possible, because modern computer processors, logic circuits,
controllers and other information processing electrical components
of electronic circuits are usually capable of operating at
frequencies which are higher than those frequencies which can be
reliably conducted by conventional cables and conductors which
interconnect physically separate circuits. The interconnecting
conductors can therefore become a limitation on the bandwidth of
the system as a whole. It is for this reason that it is important
to maximize the bandwidth of the of electrical conductors which
interconnect physically separate high frequency electronic
circuits.
Coaxial cables and microstrip flexible circuits ("flex circuits")
are frequently selected to connect the physically separated
electronic circuits, because these types of electrical conductors
offer advantages of maintaining a relatively high bandwidth. A
coaxial cable has a shielding conductor which shields each
individual signal carrying conductor from exterior radiated signals
and noise. The shielding prevents the external noise from
interfering with the desired signal. A flex circuit establishes a
controlled impedance between the signal carrying conductor and a
ground or reference plane. The signal shielding and controlled
impedance are each very useful in maintaining the quality and
integrity of the signal, thereby achieving a greater bandwidth.
Microstrip flex circuits are usually used to connect electronic
circuits which are separated by only a short distance, usually less
than a meter. Coaxial cables are usually employed to carry signals
over greater distances. Microstrip flex circuits are not normally
connected directly to coaxial cables. If a connection is made
between a microstrip flex circuit and a coaxial cable, it is
usually through an electronic circuit.
Even though a coaxial cable or a flex circuit may have enhanced
signal carrying capabilities, those capabilities can be
significantly degraded if the connection of the coaxial cable or
the flex circuit to the electronic circuit is not adequate. A
faulty connection to the circuit board can reduce or compromise the
bandwidth of the high frequency signals just as much or more than a
limited bandwidth resulting from the conductor itself.
The typical technique of connecting a coaxial cable to an
electronic circuit is with a terminating connector. The terminating
connector includes a center conductor to electrically connect a
center conductor of the coaxial cable to the conductor traces of
the circuit board. An exterior mechanical connector device, such as
a threaded nut or a mechanical friction fit retaining device,
electrically connects the shielding conductor to the ground
reference of the electronic circuit and mechanically holds the
coaxial cable in place. The threaded nut or friction fit retaining
device occupies a relatively large amount of physical space at the
edge of the electronic circuit, thereby limiting the number of
connections which may be made in a given space.
In those situations where a relatively large number of coaxial
cables must be connected to a circuit board of a relatively small
size, the physical space requirements for mechanically connecting
the coaxial cables may be greater than can be accommodated. In
those cases, the shielding conductors of two or more coaxial cables
are typically connected to a single mechanical device, thereby
gaining some additional space. One typical approach to consolidate
the shielding conductors has been to connect the shielding
conductors of two adjacent coaxial cables and then insert the two
connected shielding conductors in a ground plane receptacle.
Another approach has been to solder a jumper wire to the connected
shielding conductors and then insert single jumper into the ground
plane receptacle. As a result, only three connections are required
to interconnect two coaxial cables to an electronic circuit. The
number of conductors or the "signal density" of connections is
thereby raised.
The disadvantage of connecting the shielded conductors of two or
more coaxial cables to the ground plane at a single solder
connection or with a jumper is that the bandwidth of the coaxial
cable is usually reduced as a result of this connection. The
connection of the shielding conductors at the location where they
are joined together creates relatively high inductances, resulting
in signal path discontinuities, which reduces the bandwidth of the
coaxial cable.
One of the disadvantages of connecting a multi-layer microstrip
flex circuit to an electronic circuit board involves the connection
of the inner ground plane conductor and the interior microstrip
traces to the electronic circuit. The typical approach is to form
individual connection pads on the exterior of the flex circuit and
connect the connection pads to the interior ground plane and to the
interior microstrip traces with plated through holes known as
"vias." The vias route signals from the conductors inside the flex
circuit to the outside connection pads. The vias and connection
pads are then soldered to bonding pads of the electronic
circuit.
To keep the impedance of the via to the connection pad controlled,
each via must be very small in size, such as on the order of 0.005
inch. Making vias this small is very difficult. Consequently larger
vias are typically employed, even though the larger vias typically
introduce signal discontinuities and reduce the bandwidth of the
signals conducted by the microstrip flex circuit.
It is with respect to these considerations and other background
information that significant improvements in the field of
interconnecting coaxial cables, microstrip flex circuits and
electronic circuits have evolved.
SUMMARY OF THE INVENTION
One of the important aspects of a connection assembly of the
present invention is a coaxial cable to microstrip flex circuit
connector which achieves a relatively high number of electrical
connections in a relatively small area, which achieves the
connections in a manner which does not substantially reduce or
compromise the bandwidth of the signals conducted through the
conductor assembly, which allows selective connection and
disconnection of the coaxial cables and the microstrip flex
circuit, which can be constructed in a relatively convenient manner
using many conventional printed circuit fabrication techniques, and
which can be connected, disconnected and assembled in a relatively
convenient manner.
In accordance with this aspect of the invention, the coaxial cable
to microstrip flex circuit connector comprises a coaxial cable
attachment portion which is mechanically attached to the coaxial
cable and a microstrip flex circuit attachment portion which is
mechanically attached to the microstrip flex circuit. The coaxial
cable attachment portion includes a first electrical connector
electrically connected to the center conductor and a second
electrical connector electrically connected to the shielding
conductor of each coaxial cable. The microstrip flex circuit
attachment portion includes a third electrical connector
electrically connected to each trace and a fourth connector
electrically connected to the ground plane conductor. The coaxial
cable attachment portion and the microstrip flex circuit attachment
portion mate with one another to separately connect the first and
third electrical connectors and the second and fourth electrical
connectors.
The first and second electrical connections are preferably sockets
and the third and fourth electrical connections are preferably
inserts which fit within the sockets. A plurality of coaxial cables
may be connected to the coaxial cable attachment portion, and a
center conductor of each coaxial cable is connected to a first
connector. The second electrical connectors are connected to at
least one, and preferably a plurality of, shielding conductors. A
grounding clip preferably connects to shielding conductors of a
plurality of coaxial cables. The grounding clip preferably includes
a projection portion connected to a second electrical connector,
thereby achieving a plurality of ground connections through a
single electrical connector. The third and fourth electrical
connectors each preferably include a contact end of the insert
which contacts traces, ground trace pads or exposed areas of the
ground plane conductor of the microstrip flex circuit. Typically,
the microstrip flex circuit includes traces formed on opposite
sides of the ground plane conductor with a layer of insulation
positioned between the traces and the ground plane conductor. The
third and fourth electrical connectors are located in spaced apart
rows and the microstrip flex circuit is positioned between the rows
with the contact ends of the inserts contacting the traces, exposed
areas and ground trace pads on both sides of the microstrip flex
circuit.
Another important aspect of the connection assembly of the present
invention is a microstrip flex circuit to electrical circuit
connector which also achieves a relatively high density of
electrical connections, which achieves the connections in a manner
which does not substantially reduce or compromise the bandwidth of
the signals conducted, and which can be constructed and assembled
in a relatively convenient manner.
In accordance with this aspect of the invention, the microstrip
flex circuit to electrical circuit connector comprises a plurality
of unsupported extensions of the microstrip traces and the ground
plane conductor extending from the microstrip flex circuit. Each
extension is electrically surface connected to bonding pads of a
printed circuit board of the electronic circuit. Typically the
microstrip flex circuit includes traces formed on opposite sides of
the ground plane conductor with a layer of insulation positioned
between the traces and the ground plane conductor. The printed
circuit board of the electronic circuit may typically include
bonding pads formed on opposite sides of the printed circuit board.
The microstrip flex circuit to electrical circuit connector allows
an extension from one side of the flex circuit to bend and connect
to a bonding pad adjacent to the other side of the flex circuit.
The extensions from the ground plane conductor also bend to connect
to the bonding pads on both sides of the printed circuit board. A
potting compound or adhesive preferably establishes a mechanical
connection of the microstrip flex circuit to the circuit board at
the location of the extensions and the bonding pads.
A further important aspect of the connection assembly of the
present invention is a coaxial cable to coaxial cable connector
which also achieves a relatively high density of electrical
connections, which achieves the connections in a manner in which
does not substantially reduce or compromise the bandwidth of the
signals conducted, and which can be constructed and assembled in a
relatively convenient manner.
In accordance with this aspect of the invention, the coaxial cable
to coaxial cable connector comprises first and second attachment
portions which are similar to the coaxial cable attachment portion
and the flex circuit attachment portion of the coaxial cable to
flex circuit attachment portion. Grounding clips are employed in
the first and second attachment portions to connect the shielding
cables of the interconnected coaxial cables through the mated first
and second attachment portions. First electrical connectors such as
the sockets and second electrical connectors such as the inserts
are retained in bodies of the first and second attachment portions.
The first and third electrical connectors are connected to the
center conductors of the coaxial cables, and the electrical
connection between the attachment portions is achieved in the same
manner as the coaxial cable to flex circuit connector.
A more complete appreciation of the present invention and the scope
thereof can be obtained by reference to the accompanying drawings
which are briefly summarized below, to the following detailed
description of a presently preferred embodiment of the invention,
and to the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an electronic circuit board
assembly formed by a plurality of small electronic circuits to
which a connection assembly of the present invention is
connected.
FIG. 2 is an enlarged view of one small electronic circuit and of
the connection assembly shown in FIG. 1, in which there is shown in
greater detail, a plurality of coaxial cables, a coaxial cable to
flexible circuit connector, a stripline or microstrip flexible
circuit, a coaxial cable to coaxial cable connector, a microstrip
flexible circuit to electronic circuit connector and a coaxial
cable to coaxial cable connector.
FIG. 3 is an enlarged and partial section view of the coaxial cable
to microstrip flex circuit connector shown in FIG. 2, taken
substantially in the plane of line 3--3.
FIG. 4 is a section view taken substantially in the plane of line
4--4 in FIG. 3.
FIG. 5 is a further enlarged partial section view of a portion of
FIG. 4.
FIG. 6 is a view similar to FIG. 5 taken substantially in the plane
of line 6--6 in FIG. 3.
FIG. 7 is an enlarged, partial, perspective and exploded view of a
coaxial cable attachment portion and a portion of a microstrip
flexible circuit attachment portion of the coaxial cable to flex
circuit connector portion of the connection assembly shown in FIG.
2.
FIG. 8 is an enlarged, partial, perspective and exploded view of
the remaining portion of the microstrip flexible circuit attachment
portion not shown in FIG. 7.
FIG. 9 is an enlarged, partial, perspective and exploded view of
the microstrip flexible circuit to electronic circuit connector
shown in FIG. 2.
FIGS. 10, 11 and 12 are partial views of an alternative embodiment
of the microstrip flexible circuit to electronic circuit connector
similar to those views shown in FIGS. 3, 4 and 9, respectively.
FIG. 13 is an enlarged, partial, perspective and exploded view of a
coaxial cable to coaxial cable connector of the connection assembly
shown in FIG. 2 and of a socket retaining portion of the coaxial
cable to coaxial cable connector.
FIG. 14 is an enlarged, partial, perspective and exploded view of
an insert retaining portion of the coaxial cable to coaxial cable
connector shown in FIG. 13.
FIG. 15 is a schematic circuit diagram of the connection assembly
shown in FIG. 2.
DETAILED DESCRIPTION
A connection assembly 20 which embodies the present invention is
shown in FIGS. 1 and 2. The connection assembly 20 connects a
plurality of conventional coaxial cables 22 to an electronic
circuit 24. The electronic circuit 24 is preferably capable of
transmitting and receiving signals over the connection assembly 20
at relatively high frequencies. The electronic circuit 24 will
typically be constructed in the conventional manner, on a printed
circuit board 25 to which a number of electronic components such as
semiconductor dies or chips 26 are attached and interconnected by
conventional conductive printed circuit board ("PCB") traces (not
shown).
The connection assembly 20 of the present invention is illustrated
in FIGS. 1 and 2 in use with electronic circuits 24 of the type
used by the assignee hereof on its supercomputers. More details
concerning these electronic circuits are found in the assignee's
U.S. Pat. Nos. 5,054,192; 5,014,419; 5,045,975; and 5,195,237,
among others. The electronic circuits 24 are approximately one inch
square, and sixteen chips 26 are connected on one or both sides of
the circuit board 25. A cover 27 covers the chips 26 on each side
of the electronic circuit 24 to establish cooling channels through
which a dielectric insulating cooling fluid flows. The electronic
circuits 24 are spaced from a larger circuit retaining board 28 by
spacers 29, also to establish a cooling path between the chips and
the retaining board 28, as is discussed in the assignee's U.S. Pat.
No. 5,260,850. The coaxial cables 22 used with the assignee's
circuits are micro-coaxial cables.
Although the connection assembly 20 offers significant advantages
in communicating high frequency signals in a supercomputer, it is
not specifically required that it be employed for that purpose. The
present invention can be employed in a wide variety of electrical
connection situations and environments, including those where the
coaxial cables are of the standard size and the frequency of the
signals is not regarded as high.
The connection assembly 20 includes a conventional stripline or
microstrip flexible circuit 32 which is connected to the coaxial
cables 22 by a coaxial cable to microstrip flexible circuit
connector 34 referred to herein as a "coax to flex connector 34".
The stripline or microstrip flex circuit ("flex circuit") 32
includes a plurality of parallel-extending, conventional
microstrips or traces 36 which carry individual signals between
ends of the flex circuit 32, as are also shown in FIGS. 3 and 4.
Extensions 38 of the flex traces 36 are connected to bonding pads
40 (FIG. 9) on the printed circuit board 28. The bonding pads 40
are formed as integral parts of PCB traces on the electronic
circuit 24.
The new and improved features of the connection assembly 20 reside
in the coax to flex connector 34, in the connection of the flex
circuit 32 to the electronic circuit 24 by the extensions 38 and
pads 40, and in a coaxial cable to coaxial cable connector 41
referred to below as a "coax to coax" connector 41. The coax to
coax connector 41 is used to connect segments or lengths of coaxial
cables 22.
Details concerning the coax to flex connector 34 are shown in FIGS.
3-7. The coax to flex connector 34 includes a first or coaxial
cable attachment portion 42 to which the coaxial cables 22 are
mechanically and electrically connected. The portion 42 of the
connector 34 is referred to herein as a "coax attachment portion"
42. The coax attachment portion 42 receives and connects to the
plurality of coaxial cables 22. All of the coaxial cables 22 have
the same basic conventional configuration, shown in FIG. 7. An
outer electrical insulating cover 44 surrounds a shielding
conductor 46, which is shown as a braid. The shielding conductor 46
surrounds and encircles insulation 48 formed in the shape of
annular tube. The insulation 48 surrounds a center conductor 50.
The center conductor 50 carries the signals while the shielding
conductor 46 prevents or inhibits the influence of radiated
signals, both from external sources and from the center conductor
50.
The coax to flex connector 34 includes a second or microstrip
flexible circuit attachment portion 52 to which the flex circuit 32
is mechanically and electrically connected. The portion 52 of the
connector 34 is referred to below as a "flex attachment portion"
52. The flex circuit 32, to which the flex attachment portion 52 is
connected, is of a conventional construction as shown in FIGS. 4-6,
8 and 9.
The flex circuit 32 includes a center, sheet-like ground plane
conductor 54 which extends the width of the microstrip flex circuit
32. Uniform thickness and controlled impedance electrical
insulation layers 56 are attached to the opposite planar surfaces
of the ground plane conductor 54. The flex traces 36 are attached
to the exterior surfaces of the insulating layers 56. The exterior
of the flex traces 36 and the space between the flex traces is
occupied by an exterior insulation layer 60.
The flex attachment portion 52 of the connector 34 is adapted to
mate with the coax attachment portion 42 of the connector 34. When
the coax and flex attachment portions 42 and 52 are mated together,
signals are conducted between the center conductor 50 of the
coaxial cable 22 and individual flex traces 36 of the flex circuit
32. An electrical connection between the shielding conductor 46 of
the coaxial cable 22 and the ground plane conductor 54 of the flex
circuit 32 is also established. In general, the electrical
connections through the mated coax and flex attachment portions 42
and 52 are established by inserts 62 of the flex attachment portion
52 and sockets 64 of the coax attachment portion 42 which connect
with one another.
Details of the coax attachment portion 42 are shown in FIGS. 4-6
and 7. The coax attachment portion 42 includes a block-like
insulating body 66 into which a number of cylindrical holes 68 are
formed. The body 66 is preferably formed of plastic, but other
electrical insulating materials are suitable. The holes 68 are
arranged in rows, and preferably in a plurality of rows (two are
illustrated). The sockets 64 fit within the holes 68 when the flex
and coax attachment portions 52 and 42 are mated. The sockets 64
are metallic conductive tubes, preferably a copper-beryllium alloy.
By proper selection of the type of plastic or other insulating
material used for the body 66 and the spacing of the holes 68, a
controlled impedance path through the body 64 is achieved.
The shielding conductors 46 of two coaxial cables adjacent one
another in each row are commonly connected by a grounding clip 70,
which is shown in FIG. 7. The grounding clip 70 is preferably
stamped from sheet copper to provide a low inductance ground path
at relatively high signalling frequencies. The grounding clip 70
includes two wing portions 72 and a projection portion 74. The
projection portion 74 extends generally from the location where the
two wing portions 72 join on the clip 70. Each wing portion 72 is
bent or crimped to surround and contact the shielding conductor 46
of the two adjacent coaxial cables 22. Each wing portion 72 retains
a coaxial cable in a location aligned with the first and third
holes 68 of three adjacent holes 68 in a row on the body 66. The
projection portion 74 of the grounding clip 70 extends generally in
alignment with the two retained coaxial cables, at a position to
extend into the middle one of the three adjacent holes 68 in the
row of holes formed in the body 66.
One socket 64 is electrically and mechanically connected to the
center conductor 50 of each coaxial cable 22 and to the projection
portion 74 of the grounding clip 70, preferably by crimping an end
of the socket 64 around the conductors 50 and projection portion
74, or by soldering. The outer cover 44, shielding conductor 46,
inner insulation 48 and center conductor 50 are all stripped in a
stepped configuration as shown to accommodate this connection. The
end of the outer cover 44 preferably contacts or is closely
adjacent to the wing portions 72 at the location where they are
bent around the shielding conductor. The inner insulation 48 is
preferably adjacent to the socket 64 in the final assembled
form.
After crimping the sockets 64 on the conductors 50 and projection
portion 74 of the grounding clip 70, the sockets 64 are inserted
into the holes 68 until ends 75 of the sockets 64 project a
predetermined distance beyond a mating contact surface 76 of the
body 66, as shown in FIGS. 5 and 6. The sockets 64 are held in the
holes 68 by a suitable adhesive or by the resilient forces
developed by the compression of the sockets 64 as they are inserted
in slightly undersized holes 68. The contact surface 76 is adapted
to contact a complementary mating contact surface 84 of a body 80
of the flex attachment portion 52 of the connector 34.
The bent wing portions 72, which are bent into contact with the
shielding portions 44 of the two coaxial cables 22, hold the
coaxial cables in position in alignment with one another and with
the holes 68 and the sockets 64. The crimped connections also help
maintain the position of the sockets 64 in the holes 68 and a
mechanical connection of the coaxial cables 22 to the coax
attachment portion 42.
Additional assemblies of two coaxial cables connected by a
grounding clip 70 with attached sockets 64 are inserted into the
other groups or sequences of three adjacent holes 68 in each row of
holes, until all of the remaining holes in the body 66 are filled.
To complete the mechanical attachment of the coaxial cables 22 to
the coax attachment portion 42, an epoxy potting compound 78 (FIG.
4) is placed around the exposed portion of the grounding clip 70
and the coaxial cables. Once cured, the potting material 78 holds
all of the elements in place on the body 66 to complete the coax
attachment portion 42 of the connector 34.
The coax attachment portion 42 of the connector 34 achieves
numerous improvements. The grounding clips 70 are a relatively
small size, which allows the coaxial cables 22 to be placed
relatively closely together. The contact of the wing portion 72
with the shielding conductor 46 does not consume substantially
greater space than is consumed by the exterior cover 44 of the
coaxial cable 22. More coaxial cables 22 can be placed at
relatively closer locations along the body 66 than would be
possible if exterior connection nuts or other space consuming
devices were used to connect the shielding conductors 46. In
addition, each grounding clip 70 provides a ground electrical
connection for two coaxial cables 22, thus eliminating one of the
exterior ground connections typically required for each coaxial
cable. As a result three connectors are adequate to provide a high
bandwidth connection for two coaxial cables. By eliminating one of
the connectors for each two coaxial cables through use of the
grounding clip 70, which consumes no more space than the exterior
of the coaxial cable itself, a higher density of coaxial cables may
be connected in a smaller amount of space.
The flex attachment portion 52 of the connector 34 is shown FIGS.
2-8. The flex attachment portion 52 includes a block-like
insulating body 80 into which a number of cylindrical holes 82 are
formed. The holes 82 are arranged at locations adapted to be
coaxial with the centerline of the sockets 64 of the coax
attachment portion 42. Consequently, the number of holes 82, the
number of rows of holes 82 and the location of the holes 82
correspond to the number, rows and locations of the holes 68 in the
body 66 of the coax attachment portion 42. The diameter of the
holes 82 is slightly larger than the outside diameter of the
sockets 64, to comfortably receive the projecting ends 75 of the
sockets 64 when the coax and flex attachment portions 42 and 52 are
connected. When connected, the mating surface 76 of the coax
attachment portion 42 abuts a mating surface 84 of the flex
attachment portion 52, as is shown in FIGS. 5 and 6.
One insert 62 is positioned in each of the holes 82. Details of
each insert 62 are best shown in FIGS. 5, 6 and 8. Each insert 62
is initially stamped from a conductive sheet material such as
copper-beryllium alloy and is then bent into the shape shown in
FIG. 8. Each insert 62 includes a hollow body portion 88 from which
fingers 90 project. The fingers 90 are attached on opposite sides
of the body portion 88 and are curved to assume a mirror image
configuration with respect to one another. A projecting end 92 of
each of the fingers 90 is more closely positioned to the opposite
finger 90 than an intermediate portion 94 of the fingers 90 between
the end 90 and the body 88. The two fingers 90 therefore assume a
shape similar to tongs or tweezers.
A single contact 96 projects in the opposite direction from the
body 88 compared to the direction of projection of the fingers 90.
The contact 96 extends generally in alignment with one of the
fingers 90. The contact 96 is bent in somewhat of an S-shape as
shown in FIGS. 5 and 6 and has an inner surface 98 adapted to
contact an exposed end 100 of a microstrip trace 36 or an exposed
area 102 of the ground plane conductor 54 of the flex circuit
32.
The fingers 90 and the S-shaped contact 96 both have spring
characteristics which allow them to create resilient force when
deflected. The force from deflection of the contact 96 causes the
region 98 to press firmly against the end 100 of the microstrip
trace 36 (FIG. 5) or to press firmly against the exposed area 102
of the ground plane conductor 54 (FIG. 6) to establish good
contact. The contacts 96 are then preferably soldered to the ends
100 of the traces 36 and to the exposed areas 102 of the ground
plane conductor 54 at the regions 98. Similarly, force from the
inward deflection of the fingers 90 toward one another as they are
inserted into the socket 64 causes force from intermediate regions
94 of both fingers to establish a good electrical contact with the
interior wall of the socket 64, as is shown in FIGS. 5 and 6.
The inserts 62 are positioned in the holes 82 at a location where
the projecting ends 92 of the fingers 90 are recessed in the holes
82 from the mating surface 84, as shown in FIGS. 3-6. In this
position, the fingers 90 will not project beyond the body 80 to
avoid unintentional contact and damage when the flex attachment
portion 52 is not connected to the coax attachment portion 42.
However, even in this recessed position, the fingers 90 adequately
project into the sockets 64 to establish good electrical contact
when the mating surfaces 76 and 84 contact one another upon
connection of the portions 42 and 52 of the connector 34. The
projecting ends 75 of the sockets 64 extend into the holes 82 to
align the coax and flex attachment portions before they are mated
together. Because the sockets 62 offer more strength, there is less
risk of accidental damage of them as a result of their projection
from the body 66 of the attachment portion 42. As the coax and flex
attachment portions mate together, the projecting ends 92 move
easily into the interior of the sockets 64 at the end 75, and
further movement resiliently compresses the fingers 90 within the
interior of the socket.
The position of the inserts 62 in the holes 82 of the body 80
causes the S-shaped contacts 96 to extend almost entirely from the
holes 82. The inserts 62 are maintained in position by an adhesive,
or by frictional contact of the body portion 88 with the round
holes 82. In this position, the contacts 96 contact the connection
pads 100 formed at the ends of the microstrip traces 36, and the
contacts 96 also contact the exposed areas 102 of the ground plane
conductor 54, when the microstrip flex circuit 32 is inserted
between the two rows of S-shaped contacts (FIG. 4).
To expose the connection pads 100 of the traces 36, the outer
insulation layer 60 is removed from the flex traces 36 in those
locations of the pads 100 where the intermediate regions 98 of the
contacts 96 make contact, as shown in FIGS. 5 and 8. The outer
insulation 60 and the inner insulation layer 56 are both removed
from the flex circuit 32 in those exposed areas 102 where the
intermediate regions 98 of the contacts 96 make contact with the
ground plane conductor 54, as shown in FIGS. 6 and 8.
The flex circuit 32 is maintained in connection with the flex
attachment portion 52 by soldering the finger regions 98 and
covering them with epoxy potting compound 104. The cured epoxy
potting compound 104 also assists in maintaining the inserts 62 in
position in the flex connector portion 52. By proper selection of
the type of plastic or other insulating material used for the body
80 and the spacing of the holes 82, a controlled impedance path
through the connector body 80 is achieved.
In this manner, the coax to flex connector 34 establishes an
electrically conductive signal path between the inner
signal-carrying conductors 50 of the coaxial cables 22 and the flex
traces 36 of the flex circuit 32, through the inserts 62 and the
sockets 64. A conductive path between the ground plane conductor 54
of the flex circuit 32 and the shielding conductor 46 of each
coaxial cable 22 is also established through the inserts 62, the
sockets 64 and the grounding clips 70.
As can be appreciated from FIG. 7, those sockets 64 which are
connected to the projection portion 74 of the grounding clips 70
are located at every third position in a sequence of holes 68 in
each row. The insulation layers 56 and 60 of the flex circuit must
be removed to expose the areas 102 of the ground plane conductor 54
in locations which align with every third hole 68, as is shown in
FIG. 8. In this manner, the contacts 96 of the inserts 62 which
mate with the sockets 64 connected to the grounding clips 70 will
contact the exposed areas 102. Since a microstrip flex circuit 32
is formed in a manner generally similar to the manner of formation
of a printed circuit board, the location of the traces 36, the
location of the exposed areas 102 of the ground plane conductor 54,
and the size of the flex circuit is readily fabricated to meet
these requirements.
To align the attachment portions 42 and 52 of the coax to flex
connector 34 before connecting them together, it is advantageous to
incorporate an alignment pin 106 and alignment holes 108 and 110 in
the bodies 66 and 80 of the attachment portions 42 and 52,
respectively, as shown in FIGS. 3, and 7. The alignment pin 106 is
preferably permanently retained in hole 110 of the body 66 by an
adhesive or by press fitting the shank of the pin 106 into a
slightly undersized hole. A similar alignment pin 106 and alignment
hole 108 are located on the opposite side of the connector 34. The
alignment pins and holes assure that the sockets 64 will fit within
the holes 82 when the attachment portions 42 and 52 are mated
together.
Tooling holes 112 are another feature of the coax to flex connector
34, as shown in FIG. 2. The tooling holes 112 are formed in the
bodies 66 and 80 at an exterior side which extends at an angle to
the mating surfaces 76 and 84. A tool (not shown) may be inserted
into the holes 112 to apply force to the attachment portions 42 and
52 for either separating them or mating them. The holes 112 are
slightly tapered in an inward direction to assist in inserting and
removing the tool. The holes 112 allow one tool to be used for both
separating and mating the attachment portions 42 and 52. This is an
advantage compared to some types of connectors which require one
type of tool to separate the connector portions and a different
tool to join the connector portions. The holes 112 may be formed
completely through the bodies 66 and 80 at locations which do not
interfere with the electrical conductors, or they may be formed
partially into the bodies 66 and 80 from an exterior location and
on one or both sides of the bodies.
In addition the separating and mating functionality facilitated by
the holes 112, the holes 112 may also be formed with sufficient
precision in size and location to be useful as fixturing points
during mechanical assembly of each attachment portion 42 and 52,
during testing of the connector 34 and each attachment portion 42
and 52. Furthermore, the holes 112 can be used to accommodate a
clamping frame whose purpose is mate and disconnect several
connectors 34 simultaneously. The holes 112 can also be used for
retaining the connector 34 to some type of exterior structure.
An alternative approach of connecting the flex circuit 32 to the
attachment portion 52 is shown in FIGS. 10-12. In this alternative
embodiment, the ground plane conductor 54 is not exposed at the
areas 102 as described above. Instead, separate ground trace pads
114 are formed on the insulation layers 56 in the same plane and
adjacent to the connection pads 100 of the traces 36. The ground
trace pads 114 are connected to the ground plane conductor 54 by
conventional plated through holes or vias 116. Each via 116 extends
through the insulation layers 56 and through holes formed in the
ground plane conductor 54 and the ground trace pads 114. The
plating which forms each via 116 electrically connects to the edges
of the ground plane conductor 54 and the ground trace pads 116 at
the location of the hole in which the via 116 is located.
The ground trace pads 114 are similar in construction to the
connection pads 100 of the flex traces 36. The vias 116 are formed
in the area of the ground trace pads 114 at a location slightly
beyond the ends of the contacts 96. As is shown in FIG. 10, the
ground trace pads are located on opposite sides of the flex circuit
32 to allow a single via 116 to extend through the flex circuit and
connect two ground trace pads 114 on opposite sides of the ground
plane conductor 54. Thus, each insert 62 which mates with a socket
64 that is connected to a grounding clip 70 is electrically
connected to the ground plane conductor 54.
The force from deflection of the contact 96 causes the region 98 to
press firmly against the ground trace pad 114 to establish good
electrical contact, in the same manner that the force from
deflection of the contact 96 causes a good electrical contact with
the connection pads 100 of the traces 36. It is desirable to have
the ground path connections be of an impedance as low as possible,
to avoid signal distortions. The vias 116 can be made large and
therefore relatively easy to fabricate. In other situations, the
vias would have to be made relatively small to obtain impedance
matching.
Details concerning the connection of the microstrip flex circuit 32
to the electronic circuit 24 are shown in FIGS. 3, 4 and 9. In
general, the extensions 38 of the flex traces 36 and similar
extensions 38 of the ground plane conductor 54 extend from the flex
circuit 32. The extensions are unsupported by the other portions of
the flex circuit 32 as a result of removing and eliminating the
insulation layers 56 and 60, the traces 36 and the ground plane
conductor 54 surrounding the extensions 38. The unsupported
extensions 38 are connected, preferably by a reflow solder
technique, to the flat bonding pads 40 located along an edge of the
circuit board 28.
Because the extensions 38 are not supported at the end of the flex
circuit 32, the extensions 38 can contact the pads 40 on one or
both sides of the circuit board 26. FIG. 9 illustrates three
adjoining extensions 38 on the upper surface (as shown) of the flex
circuit 32 connected to bonding pads 40 on the same upper surface
of the circuit board 28. As is also illustrated in FIGS. 4 and 9,
the extensions 38 from the traces 36 on both sides of the ground
plane conductor 54 may be bent in an offset manner to lie in a
single plane. Thus the extensions 38 may be bent to accommodate
attachment to the bonding pads on either side of a circuit board or
at any planar location along the thickness (shown in FIG. 4) of the
flex circuit 32. To create structural strength at the connection of
the flex circuit 32 to circuit board 28 of the electronic circuit
24, a bead of structural potting compound 118 such as epoxy is
added to connect the circuit board and the flex circuit.
A relatively large sized face to face solder connection of the
extensions 38 to the bonding pads 40 creates a surface mount
connection with a very high bandwidth and impedance control. A very
high density of circuit connections is achieved by this technique,
because of the relatively close spacings between adjoining
extensions 38 and adjoining pads 40 and 100. The use of unsupported
leads in the surface soldering connection eliminates the difficult
prior art technique of blind soldering surface pads of the flex
circuit 32 which are connected by small vias to traces 36.
Details of the coax to coax connector 41 are shown in FIGS. 13 and
14. The coax to coax connector 41 includes a socket retaining
portion 120 and an insert retaining portion 122. Many of the
components employed in the socket retaining portion 120 and the
insert retaining portion 122 are the same as or very similar to
those employed in the coax to flex connector 34.
The socket retaining portion 120 of the coax to coax connector 41
includes a body 124 of electrically insulating material, as is
shown in FIG. 13. A plurality of holes 126 are formed in the body
124 in a row. Multiple rows of holes 126 could also be formed in
the connector body 124 if the size of the socket retaining portion
120 permits. Sockets 62 are inserted in the holes 126 until the
ends 75 of the sockets 62 project beyond a mating surface 128 of
the body 124 by a predetermined length. The sockets 62 are retained
in the body 124 in the same manner previously described in
conjunction with the coax attachment portion 42 of the coax to flex
connector 34. The sockets 62 are also connected to the coaxial
cables 22 and to the grounding clip 70 in the same manner described
in conjunction with the coax attachment portion 42. Adhesive
bonding material 130, such as epoxy, helps retain the coaxial
cables 22, the grounding clips 70 and the sockets 62 to the body
124.
The insert retaining portion 122 includes a body 132 of
electrically insulating material with a plurality of holes 134
formed therein in a row, as is shown in FIG. 14. Multiple rows of
holes 134 may be formed in the connector body 132 if the size
permits. The number of holes 134, the number of rows of holes 134,
and the location of the holes 134 in the body 132 should correspond
to those in the socket retaining portion 120 to allow the retaining
portions to mate. A mating surface 136 of the body 132 contacts the
mating surface 128 of the socket retention portion 120 (FIG. 13)
when the portions 120 and 122 are connected together.
Inserts 138 are connected to the projection portion 74 of the
grounding clips 70 and to the center conductors 50 of the coaxial
cable 22, preferably by crimping an end of the socket 64 or by
soldering. The outer cover 44, shielding conductor 46, inner
insulation 48 and center conductor 50 are all stripped in a stepped
configuration as shown to accommodate this connection. The end of
the outer cover 44 preferably contacts or is closely adjacent to
the wing portions 72 of the grounding clip 70 at the location where
they are bent around the shielding conductor 46. After connecting
the inserts 138, they are inserted into and retained in the holes
134 in the body 132. The inserts 138 are similar to those inserts
62 used in the flex connector portion 52 (FIG. 8) except that the
S-shaped contact 96 is removed from the inserts 138. In addition,
the body portion 88 of each insert 138 is crimped or otherwise
connected to the center conductor 50 of the coaxial cables 22 and
to the projection portion 74 of the grounding clip 70. The wing
portions 72 of the grounding clip 70 are bent around and connected
to the shielding conductors 46 of coaxial cables in the manner
previously described. The inserts 138 are retained in the holes 134
by an adhesive or by a friction fit of the body portion 88 within
the holes 134. Adhesive or epoxy material 140 (FIG. 13) helps
retain the coaxial cables 22 to the body 132.
The socket retaining portion 120 mates with the insert retaining
portion 122 of the coax to coax connector 41 in essentially the
same manner that the attachment portions 52 and 42 of the coax to
flex connector 34 mate together as shown in FIG. 5. That is, the
fingers 90 fit within the interior of the sockets 64 to establish a
good electrical connection.
The components of the connection assembly 20 are shown in
electrical schematic form in FIG. 15. The electrical connections
and paths between the electronic circuit and the coaxial cables is
illustrated for reference and comparison purposes with respect to
the preceding description.
The connection assembly 20 establishes and maintains controlled
impedance paths which are generally shielded from exterior radiated
signals over substantially the entire length of the signal
transmission through the assembly 20. In the coax to flex connector
34 and in the flex to flex connector 41, the relatively small
region of the insert 62 and socket 64 selection of an appropriate
plastic insulating material for the connector bodies and spacing of
the socket and insert connections will achieve a specific path
impedance. As a result, both superior signal communication
bandwidth and high density electrical connections are achieved in
relatively small spaces by the connection assembly 20.
A presently preferred embodiment of the invention has been
described with a degree of particularity. This description is of a
preferred example for implementing the invention. The scope of the
invention should not necessarily be limited by this description,
but is defined by the scope of the following claims.
* * * * *