Title: Rotational grip twist machine and method for fabricating bulges of twisted wire electrical connectors
Abstract: Bulges in a wire having helically coiled strands are formed by untwisting the strands in an anti-helical direction at a predetermined position, to form an electrical connector from a length of the stranded wire. The wire is gripped by moving two spaced apart clamp members to a closed position and thereafter rotating the clamp members relative to one another in at least one complete relative revolution in a direction which is anti-helical relative to the coiled strands to form the bulge. The wire is gripped and rotated in the anti-helical direction for a relative rotational interval of greater than one-half, and preferably three-fourths, of a complete relative revolution. Thereafter, during the remaining rotational interval of each relative revolution, the clamp members are opened to permit the wire to be advanced to the next position where a bulge is to be formed.
Patent Number: 6,971,415 Issued on 12/06/2005 to Garcia, et al.
| Inventors:
|
Garcia; Steven E. (Colorado Springs, CO);
Harden, Jr.; James A. (Colorado Springs, CO)
|
| Assignee:
|
Medallion Technology, LLC (Houston, TX)
|
| Appl. No.:
|
791556 |
| Filed:
|
March 2, 2004 |
| Current U.S. Class: |
140/149; 140/71 |
| Intern'l Class: |
B21F 007/00 |
| Field of Search: |
140/71 R,147,149
29/461,745
72/299
57/1U.N
|
References Cited [Referenced By]
U.S. Patent Documents
| 1341636 | Jun., 1920 | Deschauer.
| |
| 2064545 | Dec., 1936 | Kleinmann et al.
| |
| 2234641 | Mar., 1941 | Baumgartner.
| |
| 2752580 | Jun., 1956 | Shewmaker.
| |
| 2828455 | Mar., 1958 | Kraay et al.
| |
| 3017605 | Jan., 1962 | Platz et al.
| |
| 3028720 | Apr., 1962 | Houk.
| |
| RE25798 | Jun., 1965 | Platz et al.
| |
| 3205469 | Sep., 1965 | Frank et al.
| |
| 3255430 | Jun., 1966 | Phillips.
| |
| 3258736 | Jun., 1966 | Crawford et al.
| |
| 3277560 | Oct., 1966 | Frank et al.
| |
| 3319217 | May., 1967 | Phillips.
| |
| 3333225 | Jul., 1967 | McNutt.
| |
| 3400358 | Sep., 1968 | Byrnes et al.
| |
| 3402466 | Sep., 1968 | Phillips.
| |
| 3612369 | Oct., 1971 | Grebe et al.
| |
| 3817067 | Jun., 1974 | Vorrehes et al.
| |
| 4022057 | May., 1977 | Bachman et al.
| |
| 4076356 | Feb., 1978 | Tamburro.
| |
| 4119206 | Oct., 1978 | Woodman, Jr. et al.
| |
| 4237942 | Dec., 1980 | Dietrich.
| |
| 4358180 | Nov., 1982 | Lincoln.
| |
| 4422583 | Dec., 1983 | Maxner et al.
| |
| 4505529 | Mar., 1985 | Barkus.
| |
| 4690349 | Sep., 1987 | Yamaguchi et al.
| |
| 4742973 | May., 1988 | Stomski et al.
| |
| 4773877 | Sep., 1988 | Krüger et al.
| |
| 4843315 | Jun., 1989 | Bayer et al.
| |
| 4889496 | Dec., 1989 | Neidich.
| |
| 4911645 | Mar., 1990 | August et al.
| |
| 5014419 | May., 1991 | Cray et al.
| |
| 5033785 | Jul., 1991 | Woolley, Jr.
| |
| 5050295 | Sep., 1991 | Sullivan et al.
| |
| 5051108 | Sep., 1991 | Lincoln.
| |
| 5054192 | Oct., 1991 | Cray et al.
| |
| 5106310 | Apr., 1992 | Krajewski et al.
| |
| 5112232 | May., 1992 | Cray et al.
| |
| 5129830 | Jul., 1992 | Krajewski et al.
| |
| RE34084 | Sep., 1992 | Noschese.
| |
| 5184400 | Feb., 1993 | Cray et al.
| |
| 5263307 | Nov., 1993 | Hasui.
| |
| 5277018 | Jan., 1994 | Pujol-Isern.
| |
| 5331867 | Jul., 1994 | Carpenter et al.
| |
| 5388998 | Feb., 1995 | Grange et al.
| |
| 5667410 | Sep., 1997 | Johnston.
| |
| 5676013 | Oct., 1997 | Kahlau.
| |
| 5865051 | Feb., 1999 | Otzen et al.
| |
| 5867986 | Feb., 1999 | Buratti et al.
| |
| 5904059 | May., 1999 | Perna.
| |
| 6009738 | Jan., 2000 | Beecher et al.
| |
| 6043666 | Mar., 2000 | Kazama.
| |
| Foreign Patent Documents |
| 55133355 | Oct., 1980 | JP.
| |
| 55133549 | Oct., 1980 | JP.
| |
| 568837 | Jan., 1981 | JP.
| |
| 63208237 | Aug., 1988 | JP.
| |
| 63293845 | Nov., 1988 | JP.
| |
| 3209173 | Sep., 1991 | JP.
| |
| 3209174 | Sep., 1991 | JP.
| |
| WO 9419518 | Sep., 1994 | WO.
| |
Primary Examiner: Larson; Lowell A.
Attorney, Agent or Firm: Ley; John R.
Parent Case Text
CROSS-REFERENCE TO RELATED INVENTION
This invention is a division of U.S. application Ser. No. 09/782,888, filed
Feb. 13, 2001, filed by the inventors herein, for a Rotational Grip Twist Machine
and Method for Fabricating Bulges of Twisted Wire Electrical Connectors, now U.S.
Pat. No. 6,729,026. This invention and application is also related to inventions
for High-Speed, High-Capacity Twist Pin Connector Fabricating Machine and Method,
Wire Feed Mechanism and Method Used for Fabricating Electrical Connectors, and
Pneumatic Inductor and Method of Electrical Connector Delivery and Organization,
described in U.S. patent applications Ser. Nos. 09/782,987; 09/782,991; and 09/780,981,
respectively, now U.S. Pat. Nos. 6,584,677, 6,530,511, and 6,528,759, respectively,
all of which are assigned to the assignee hereof, and all of which have at least
one common inventor with the present application. The disclosures of these U.S.
Patents are incorporated herein by this reference.
Claims
1. A bulge forming mechanism for forming bulges in a wire having helically coiled
strands by untwisting the strands in an anti-helical direction at a predetermined
position to form an electrical connector from a segment of a length of the wire, comprising:
a first gripping assembly including a first clamp member and a first actuator,
the first clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the first clamp member and to an open position
in which the wire is free to move relative to the first clamp member, the first
actuator connected to the first clamp member to selectively move the first clamp
member into the open and closed positions;
a second gripping assembly including a second clamp member and a second actuator,
the second clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the second clamp member and to an open position
in which the wire is free to move relative to the second clamp member, the second
actuator connected to the second clamp member to selectively move the first clamp
member into the open and closed positions; and
a rotating carrier interconnecting the first and second gripping assemblies to
rotate the first and second clamp members relative to one another in at least one
complete relative revolution in a single relative rotational direction which is
anti-helical relative to the strands of the wire, the rotating carrier also positioning
the first and second clamp members at a spaced apart location above and below the
predetermined location where a bulge is to be formed, and wherein:
the first and second actuators close the first and second clamp members during
a relative rotational interval of greater than one-half of a complete relative
revolution of the clamp members.
2. A bulge forming mechanism as defined in claim 1 wherein:
the first and second actuators close the first and second clamp members during
a relative rotational interval of approximately three-fourths of a complete relative
revolution of the clamp members.
3. A bulge forming mechanism as defined in claim 1 further comprising:
a drive motor connected for rotating the rotating carrier; and
the drive motor slows the relative rotation of the first and second gripping
assemblies relative to one another during the relative rotational interval when
the first and second clamp members are in the open position.
4. A bulge forming mechanism as defined in claim 1 wherein:
the first and second actuators open the first and second clamp members during
a relative rotational interval of less than one-half of a complete relative revolution
of the clamp members, the relative rotational interval when the first and second
clamp members are in the open position permits the wire to be advanced.
5. A bulge forming mechanism as defined in claim 4 further comprising:
a drive motor connected for rotating the rotating carrier to achieve a relative
rotational rate of the first and second gripping assemblies; and
the drive motor controls the relative rotational rate of the first and second
gripping assemblies relative to one another during the relative rotational interval
when the first and second clamp members are in the open position to establish selective
time intervals during which the clamp members occupy the open position.
6. A bulge forming mechanism as defined in claim 5 wherein:
the drive motor establishes the time period of the relative rotational interval
when the first and second clamp members are in the open position independently
of the time period of the relative rotational interval when the first and second
clamp members are in the closed position by controlling the relative rotational rate.
7. A bulge forming mechanism as defined in claim 6 further in combination with
a wire feeding mechanism which advances wire to the bulge forming mechanism during
the relative rotational interval when the first and second clamp members are in
the open position.
8. A bulge forming mechanism as defined in claim 4 further in combination with
a wire feeding mechanism which advances wire to the bulge forming mechanism during
the relative rotational interval when the first and second clamp members are in
the open position.
9. A bulge forming mechanism as defined in claim 8 wherein the wire feeding mechanism
advances the wire to the predetermined position where a bulge is to be formed in
the wire by the bulge forming mechanism during the relative rotational interval
when the first and second clamp members are in the open position.
10. A bulge forming mechanism as defined in claim 9 further in combination with
a wire severing apparatus which severs the segment of the wire upon which the bulges
have been formed from a remaining length of the wire, the wire feeding mechanism
advancing the wire during the relative rotational interval when the first and second
clamp members are in the open position, the wire feeding mechanism advancing the
wire to a predetermined position where it is to be severed after all of the bulges
have been formed in the segment of the wire.
11. A bulge forming mechanism as defined in claim 10 further comprising:
a drive motor electrically connected for a rotating the rotating carrier; and
the drive motor slows the relative rotation of the first and second gripping
assemblies relative to one another during the relative rotational interval when
the first and second clamp members are in the open position.
12. A bulge forming mechanism as defined in claim 11 wherein:
the drive motor temporarily stops the relative rotation of the first and second
gripping assemblies relative to one another during the relative rotational interval
when the first and second clamp members are in the open position.
13. A bulge forming mechanism as defined in claim 1 wherein:
the first and second actuators open the first and second clamp members approximately
at the same time during a relative revolution of the clamp members.
14. A bulge forming mechanism as defined in claim 1 wherein:
the first and second actuators close the first and second clamp members approximately
at the same time during a relative revolution of the clamp members.
15. A bulge forming mechanism as defined in claim 1 wherein:
the first gripping assembly is retained in a stationary position; and
the second gripping assembly is connected to the rotating carrier to rotate in
conjunction with the rotating carrier and relative to the first gripping assembly.
16. A bulge forming mechanism for forming bulges in a wire having helically coiled
strands by untwisting the strands in an anti-helical direction at a predetermined
position to form an electrical connector from a segment of a length of the wire, comprising:
a first gripping assembly including a first clamp member and a first actuator,
the first clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the first clamp member and to an open position
in which the wire is free to move relative to the first clamp member, the first
actuator connected to the first clamp member to selectively move the first clamp
member into the open and closed positions;
a second gripping assembly including a second clamp member and a second actuator,
the second clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the second clamp member and to an open position
in which the wire is free to move relative to the second clamp member, the second
actuator connected to the second clamp member to selectively move the first clamp
member into the open and closed positions; and
a rotating carrier interconnecting the first and second gripping assemblies to
rotate the first and second clamp members relative to one another in at least one
complete relative revolution in a single relative rotational direction which is
anti-helical relative to the strands of the wire, the rotating carrier also positioning
the first and second clamp members at a spaced apart location above and below the
predetermined location where a bulge is to be formed, and wherein:
one of the first or second actuators is mechanically operated; and
the other one of the first or second actuators is electrically operated.
17. A bulge forming mechanism as defined in claim 16 further comprising:
a sensor located to sense the operation of the mechanically-operated actuator
and to supply a signal upon the operation of the mechanically-operated actuator;
and wherein:
the electrically-operated actuator is operated in response to the signal from
the sensor.
18. A bulge forming mechanism for forming bulges in a wire having helically coiled
strands by untwisting the strands in an anti-helical direction at a predetermined
position to form an electrical connector from a segment of a length of the wire, comprising:
a first gripping assembly including a first clamp member and a first actuator,
the first clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the first clamp member and to an open position
in which the wire is free to move relative to the first clamp member, the first
actuator connected to the first clamp member to selectively move the first clamp
member into the open and closed positions;
a second gripping assembly including a second clamp member and a second actuator,
the second clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the second clamp member and to an open position
in which the wire is free to move relative to the second clamp member, the second
actuator connected to the second clamp member to selectively move the first clamp
member into the open and closed positions; and
a rotating carrier interconnecting the first and second gripping assemblies to
rotate the first and second clamp members relative to one another in at least one
complete relative revolution in a single relative rotational direction which is
anti-helical relative to the strands of the wire, the rotating carrier also positioning
the first and second clamp members at a spaced apart location above and below the
predetermined location where a bulge is to be formed, and wherein:
at least one of the first or second actuators is electrically operated.
19. A bulge forming mechanism as defined in claim 18 wherein:
at least one of the first or second actuators is mechanically operated.
20. A bulge forming mechanism for forming bulges in a wire having helically coiled
strands by untwisting the strands in an anti-helical direction at a predetermined
position to form an electrical connector from a segment of a length of the wire, comprising:
a first gripping assembly including a first clamp member and a first actuator,
the first clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the first clamp member and to an open position
in which the wire is free to move relative to the first clamp member, the first
actuator connected to the first clamp member to selectively move the first clamp
member into the open and closed positions;
a second gripping assembly including a second clamp member and a second actuator,
the second clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the second clamp member and to an open position
in which the wire is free to move relative to the second clamp member, the second
actuator connected to the second clamp member to selectively move the first clamp
member into the open and closed positions;
a rotating carrier interconnecting the first and second gripping assemblies to
rotate the first and second clamp members relative to one another in at least one
complete relative revolution in a single relative rotational direction which is
anti-helical relative to the strands of the wire, the rotating carrier also positioning
the first and second clamp members at a spaced apart location above and below the
predetermined location where a bulge is to be formed; and
a drive motor connected for rotating the rotating carrier in complete revolutions
in a single rotational direction; and wherein:
the second actuator is mechanically operated by rotation of the rotating carrier
to move the second clamp member into one of either the open or the closed positions
at a predetermined point in each revolution of the rotating carrier;
the first gripping assembly is retained in a stationary position; and
the second gripping assembly is connected to the rotating carrier to rotate in
conjunction with the rotating carrier and relative to the first gripping assembly.
21. A bulge forming mechanism as defined in claim 20 further comprising:
a trip pin located adjacent to the rotating carrier; and wherein:
the second actuator includes an actuating arm extending from the rotating carrier
to contact the trip pin during rotation of the rotating carrier to move the second
clamp member into one of either the open or the closed positions.
22. A bulge forming mechanism as defined in claim 21 further comprising:
a second trip pin in addition to the trip pin first aforesaid, the second trip
pin also located adjacent to the rotating carrier; and wherein:
the second actuator includes a second actuating arm in addition to the actuating
arm first aforesaid;
the first actuator arm contacting the first trip pin to move the second clamp
member into the open position; and
the second actuating arm also extending from the rotating carrier to contact
the second trip pin during rotation of the rotating carrier, the second actuating
arm contacting the second trip pin to move the second clamp member into the closed position.
23. A bulge forming mechanism as defined in claim 22 wherein:
at least one of the first or second trip pins is located at a stationary position
relative to the rotating carrier.
24. A bulge forming mechanism as defined in claim 22 wherein:
the rotating carrier comprises a carrier disk having a peripheral edge;
the second actuator comprises a cam wheel positioned for rotation relative to
the carrier disk at a location adjacent to the peripheral edge of the carrier disk; and
the cam wheel including the first and second actuator arms extending beyond the
peripheral edge of the carrier disk to contact the first and second trip pins,
respectively, upon rotation of the cam wheel relative to the carrier disk.
25. A bulge forming mechanism as defined in claim 24 wherein:
the second clamp member comprises at least one lever arm which moves the second
clamp member between the open and closed positions when pivoted; and
the cam wheel further includes a surface which contacts the lever arm and pivots
the lever arm upon rotation of the cam wheel.
26. A bulge forming mechanism as defined in claim 24 wherein:
the second clamp member comprises a pair of separated lever arms which move the
second clamp member between the open and closed positions when pivoted;
the cam wheel is positioned between the separated lever arms and further includes
a cam surface which contacts the lever arms and pivots the lever arms upon rotation
of the cam wheel as a result of one of the actuator arms contacting one of the
trip pins.
27. A bulge forming mechanism as defined in claim 26 wherein:
the second clamp member further comprises one jaw member connected to one of
the lever arms and one jaw member connected to the other lever arm, the jaw members
contacting and holding the wire when the second clamp member is in the closed position; and
rotation of the cam wheel and the cam surface pivots the lever arms to move the
connected jaw members apart and toward one another to achieve the open and closed
positions of the second clamp member, respectively.
28. A bulge forming mechanism as defined in claim 29 wherein:
each of the jaw members includes a contact surface which is crescent shaped.
29. A bulge forming mechanism as defined in claim 29 wherein:
each of the jaw members includes a contact surface shaped to reposition the strands
of the wire when contacted and held into a cross-sectional configuration having
a radial component upon movement of the second clamp member to the closed position.
30. A bulge forming mechanism as defined in claim 29 wherein:
each lever arm and the jaw member is formed from a sheet of material having a thickness;
each jaw member includes a contact surface by which to contact and hold the wire; and
the contact surface of each of the jaw members is reduced in thickness relative
to the thickness of the sheet of material to reduce a surface area of the contact
surface which contacts and holds the wire.
31. A bulge forming mechanism as defined in claim 29 wherein:
the second clamp member is formed from a sheet of spring tempered material;
the spring tempered material creates resilient characteristics in the second
clamp member; and
the resilient characteristics normally force the lever arms toward one another
to bias the second clamp member to the closed position.
32. A bulge forming mechanism as defined in claim 27 wherein:
the second clamp member further comprises an end portion to which the lever arms
are connected and from which the lever arms extend;
the lever arms and end portion are integrally formed from a sheet of spring tempered material;
the spring tempered material creates resilient characteristics in the second
clamp member; and
the end portion is connected to the carrier disk at a position diametrically
opposite from the location where the actuator wheel is rotationally positioned
on the carrier disk.
33. A bulge forming mechanism as defined in claim 32 wherein:
the second clamp member further includes an arcuate portion which connects each
lever arm to the end portion;
the resilient characteristics of the lever arms, the arcuate portions and the
end portion normally force the lever arms toward one another to bias the jaw members
toward one another when the second clamp member is in the closed position; and
the rotation of the cam wheel causes the cam surface of the cam wheel to force
the lever arms away from one another against the bias of the resilient characteristics
of the second clamp member when the second clamp member is in the open position.
34. A bulge forming mechanism as defined in claim 27 wherein:
the rotating carrier rotates about an axis of rotation;
the contact surfaces of the jaw members of the second clamp member are positioned
concentrically about an axis of rotation of the rotating carrier; and
the rotating carrier includes a hole located at the axis of rotation through
which the wire extends.
35. A bulge forming mechanism as defined in claim 21 further comprising:
a sensor located adjacent to the trip pin to sense the contact of the actuating
arm with the trip pin and to supply a signal upon such contact; and wherein:
the first actuator is operated in response to the signal from the sensor.
36. A bulge forming mechanism as defined in claim 20 wherein:
the drive motor is a stepper motor.
37. A bulge forming mechanism as defined in claim 20 wherein:
the first clamp member comprises an arm which pivots when the first clamp member
moves between the open and closed positions; and
the first actuator is connected to the arm to pivot the arm.
38. A bulge forming mechanism as defined in claim 37 wherein:
the first actuator comprises a solenoid.
39. A bulge forming mechanism as defined in claim 37 wherein:
the first clamp member further comprises a base with respect to which the arm
pivots when the first clamp member moves between the open and closed positions; and
the first clamp member further comprises one jaw member connected to the arm
and one jaw member connected to the base, the jaw members contacting and holding
the wire when the first clamp member is in the closed position.
40. A bulge forming mechanism as defined in claim 39 wherein:
each of the jaw members includes a contact surface which is semicircular shaped.
41. A bulge forming mechanism as defined in claim 40 wherein:
the arm and the base are formed from a sheet of material having a thickness;
each jaw member includes a contact surface by which to contact and hold the wire; and
the contact surface of each of the jaw members is approximately the same thickness
as the thickness of the sheet of material from which the arm and base are formed.
42. A bulge forming mechanism as defined in claim 39 wherein:
the first clamp member is formed from a sheet of spring tempered material;
the spring tempered material creates resilient characteristics in the first clamp
member; and
the resilient characteristics normally force the jaw member on the arm away from
the jaw member on the base to bias the first clamp member to the open position.
43. A bulge forming mechanism as defined in claim 42 wherein:
the first actuator comprises a solenoid having a plunger;
the plunger is connected to the arm; and
the plunger is moved by actuating the solenoid to pivot the jaw member on the
arm toward the jaw member on the base and to overcome the bias of the resilient
characteristics of the first clamp member.
44. A bulge forming mechanism as defined in claim 43 wherein:
the first clamp member further includes an arcuate portion which connects the
arm to the base;
the resilient characteristics of the arm, the base and the arcuate portion normally
bias the jaw members on the arm away from the jaw members on the base portion.
45. A bulge forming mechanism as defined in claim 44 wherein:
the arcuate portion extends in a semicircular curve to connect the arm to the base.
46. A bulge forming mechanism as defined in claim 39 wherein:
the rotating carrier rotates about an axis of rotation;
each jaw member includes a contact surface by which to contact and hold the wire; and
the contact surfaces of the jaw members are positioned concentrically about an
axis of rotation of the rotating carrier when the first clamp member is moved to
the closed position.
47. A bulge forming mechanism as defined in claim 46 wherein:
the contact surface of the jaw member on the base remains concentrically positioned
about the axis of rotation of the rotating carrier when the first clamp member
is moved to the open position.
48. A bulge forming mechanism for forming bulges in a wire having helically coiled
strands by untwisting the strands in an anti-helical direction at a predetermined
position to form an electrical connector from a segment of a length of the wire, comprising:
a first gripping assembly including a first clamp member and a first actuator,
the first clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the first clamp member and to an open position
in which the wire is free to move relative to the first clamp member, the first
actuator connected to the first clamp member to selectively move the first clamp
member into the open and closed positions; and
a second gripping assembly including a second clamp member and a second actuator,
the second clamp member moving to a closed position to grip the wire and prevent
the wire from moving relative to the second clamp member and to an open position
in which the wire is free to move relative to the second clamp member, the second
actuator connected to the second clamp member to selectively move the first clamp
member into the open and closed positions; and
a rotating carrier interconnecting the first and second gripping assemblies to
rotate the first and second clamp members relative to one another in at least one
complete relative revolution in a single relative rotational direction which is
anti-helical relative to the strands of the wire, the rotating carrier also positioning
the first and second clamp members at a spaced apart location above and below the
predetermined location where a bulge is to be formed, and wherein:
at least one of the first or second clamp members further comprises jaw members
which contact and hold the wire when the first and second clamp member are in the
closed positions; and
the jaw members of at least one of the first or second clamp members includes
a contact surface shaped to reposition the strands of the wire when contacted and
held into a cross-sectional configuration having a radial component upon movement
of the one clamp member to the closed position.
49. A bulge forming mechanism as defined in claim 48 wherein:
the contact surface of the jaw members of the one damp member are crescent shaped.
Description
FIELD OF THE INVENTION
This invention generally relates to the fabrication of electrical interconnectors
used to electrically connect printed circuit boards and other electrical components
in a vertical or z-axis direction to form three-dimensional electronic modules.
More particularly, the present invention relates to a new and improved machine
and method for fabricating z-axis interconnectors of the type formed from helically
coiled strands of wire, in which at least one longitudinal segment of the coiled
strands is untwisted in an anti-helical direction to expand the strands of wire
into a resilient bulge. Bulges of the interconnector are then inserted into vias
of vertically stacked printed circuit boards to establish an electrical connection
through the z-axis interconnector between the printed circuit boards of the three
dimensional module.
BACKGROUND OF THE INVENTION
The evolution of computer and electronic systems has demanded ever-increasing
levels of performance. In most regards, the increased performance has been achieved
by electronic components of ever-decreasing physical size. The diminished size
itself has been responsible for some level of increased performance because of
the reduced lengths of the paths through which the signals must travel between
separate components of the systems. Reduced length signal paths allow the electronic
components to switch at higher frequencies and reduce the latency of the signal
conduction through relatively longer paths. One technique of reducing the size
of the electronic components is to condense or diminish the space between the electronic
components. Diminished size also allows more components to be included in a system,
which is another technique of achieving increased performance because of the increased
number of components.
One particularly effective approach to condensing the size between electronic
components is to attach multiple semiconductor integrated circuits or "chips" on
printed circuit boards, and then stack multiple printed circuit boards to form
a three-dimensional configuration or module. Electrical interconnectors are then
extended vertically, in the z-axis dimension, between the printed circuit boards
which are oriented in the horizontal x-axis and y-axis dimensions. The z-axis interconnectors,
in conjunction with conductor traces of each printed circuit board, connect the
chips of the module with short signal paths for efficient functionality. The relatively
high concentration of chips, which are connected by the three-dimensional, relatively
short length signal paths, are capable of achieving very high levels of functionality.
The vertical electrical connections between the stacked printed circuit boards
are established by using z-axis interconnectors. Z-axis interconnectors contact
and extend through plated through holes or "vias" formed in each of the printed
circuit boards. The chips of each printed circuit board are connected to the vias
by conductor traces formed on or within each printed circuit board. The vias are
formed in each individual printed circuit board of the three-dimensional modules
at the same locations, so that when the printed circuit boards are stacked in the
three-dimensional module, the vias of all of the printed circuit boards are aligned
vertically in the z-axis. The z-axis interconnectors are then inserted vertically
through the aligned vias to establish an electrical contact and connection between
the vertically oriented vias of each module.
Because of differences between the individual chips on each printed circuit
board and the necessity to electrically interconnect to the chips of each module
in a three-dimensional sense, it is not always required that the z-axis interconnectors
electrically connect to the vias of each printed circuit board. Instead, those
vias on those circuit boards for which no electrical connection is desired are
not connected to the traces of that printed circuit board. In other words, the
via is formed but not connected to any of the components on that printed circuit
board. When the z-axis interconnector is inserted through such a via, a mechanical
connection is established, but no electrical connection to the other components
of the printed circuit board is made. Alternatively, each of the z-axis interconnectors
may have the capability of selectively contacting or not contacting each via through
which the interconnector extends. Not contacting a via results in no electrical
connection at that via. Of course, no mechanical connection exists at that via
either, in this example.
A number of different types of z-axis interconnectors have been proposed. One
particularly
advantageous type of z-axis interconnector is known as a "twist pin." Twist pin
z-axis interconnectors are described in U.S. Pat. Nos. 5,014,419, 5,064,192, and
5,112,232, all of which are assigned to the assignee hereof.
An example of a prior art twist pin 50 is shown in FIG. 1. The twist pin
50 is formed from a length of wire 52 which has been formed conventionally
by helically coiling a number of outer strands 54 around a center core strand
56 in a planetary manner, as shown in FIG. 2. At selected positions along
the length of the wire 52, a bulge 58 is formed by untwisting the
outer strands-54 in a reverse or anti-helical direction. As a result of
untwisting the strands 54 in the anti-helical direction, the space consumed
by the outer strands 54 increases, causing the outer strands 54 to
bend or expand outward from the center strand 56 and create a larger diameter
for the bulge 58 than the diameter of the regular stranded wire 52.
The laterally outward extent of the bulge 58 is illustrated in FIG. 3, compared
to FIG. 2.
The strands 54 and 56 of the wire 52 are preferably formed
from beryllium copper. The beryllium copper provides necessary mechanical characteristics
to maintain the shape of the wire in the stranded configuration, to allow the outer
strands 54 to bend outward at each bulge 58 when untwisted, and to
cause the bulges 58 to apply resilient radial contact force on the vias
of the printed circuit boards. To facilitate and enhance these mechanical properties,
the twist pin will typically be heat treated after it has been fabricated. Heat
treating anneals or hardens the beryllium copper slightly and tempers the strands
54 at the bulges 58, causing enhanced resiliency or spring-like characteristics.
It is also typical to plate the fabricated twist pin with an outer coating of gold.
The gold plating establishes a good electrical connection with the vias. To cause
the gold-plated exterior coating to adhere to the twist pin 50, usually
the beryllium copper is first plated with a layer of nickel, and the gold is plated
on top of the nickel layer. The nickel layer adheres very well to the beryllium
copper, and the gold adheres very well to the nickel.
The bulges 58 are positioned at selected predetermined distances along
the length of the wire 52 to contact the vias 60 in printed circuit
boards 62 of a three-dimensional module 64, as shown in FIG. 4. Contact
of the bulge 58 with the vias 60 is established by pulling the twist
pin 50 through an aligned vertical column of vias 60 in the module
64. The outer strands 54 of the wire 52 have sufficient resiliency
when deflected into the outward protruding bulge 58, to resiliently press
against an inner surface of a sidewall 66 of each via 60, and thereby
establish the electrical connection between the twist pin 50 and the via
60, as shown in FIG. 5. In those circumstances where an electrical connection
is not desired between the twist pin 50 and the components of a printed
circuit board, the via 60 is formed but no conductive traces connect the
via to the other components of the printed circuit board. One such via 60′
is shown in FIG. 4. The sidewall 66 of the via 60′ extends
through the printed circuit board, but the via 60′ is electrically
isolated from the other components on that printed circuit board because no traces
extend beyond the sidewall 66. Inserting a bulge 58 of the twist
pin 50 into a via 60′ that is not connected to the other components
of a printed circuit board eliminates an electrical connection from that twist
pin to that printed circuit board, but establishes a mechanical connection between
the twist pin and the printed circuit board which helps support and hold the printed
circuit board in the three-dimensional module.
To insert the twist pins 50 into the vertically aligned vias 60
of the module 64 with the bulges 58 contacting the inner surfaces
66 of the vias 60, a leader 68 of the regularly-coiled strands
54 and 56 extends at one end of the twist pin 50. The strands
54 and 56 at a terminal end 70 of the leader 68 have
been welded or fused together to form a rounded end configuration 70 to
facilitate insertion of the twist pin 50 through the column of vertically
aligned vias. The leader 68 is of sufficient length to extend through all
of the vertically aligned vias 60 of the assembled stacked printed circuit
boards 62, before the first bulge 58 makes contact with the outermost
via 60 of the outermost printed circuit board 62. The leader 68
is gripped and the twist pin 50 is pulled through the vertically aligned
vias 60 until the bulges 58 are aligned and in contact with the vias
60 of the stacked printed circuit boards. To position the bulges in contact
with the vertically aligned vias, the leading bulges 58 will be pulled into
and out of some of the vertically aligned vias until the twist pin 50 arrives
at its final desired location. The resiliency of the strands 54 allow the
bulges 58 to move in and out of the vias without losing their ability to
make sound electrical contact with the sidewall of the final desired via into which
the bulges 58 are positioned. Once appropriately positioned, the leader
68 is cut off so that the finished length of the twist pin 50 is
approximately at the same level or slightly beyond the outer surface of the outer
printed circuit board of the module 64. A tail 72 at the other end
of the twist pin 50 extends a shorter distance beyond the last bulge 58.
The strands 54 and 56 at an end 74 of the tail 72 are
also fused together. The length of the tail 72 positions the end 74
at a similar position to the location where the leader 68 was cut on the
opposite side of the module. However, if desired, the length of the tail 72
or the remaining length of the leader 68 after it was cut may be made longer
or shorter. Allowing the tail 72 and the remaining portion of the leader
68 to extend slightly beyond the outer printed circuit boards 62
of the module 64 facilitates gripping the twist pin 50 when removing
it from the module 64 to repair or replace any defective components. In
those circumstances where it is preferred that the ends of the twist pin do not
extend beyond the outside edges of the three-dimensional module, an overlay may
be attached to the outermost printed circuit boards to make the ends of the twist
pin flush with the overlay.
The ability to achieve good electrical connections between the vias 60
of the printed circuit boards depends on the ability to precisely position the
location of the bulges 58 along the length of wire 52. Otherwise,
the bulges 58 would be misaligned relative to the position of the vias,
and possibly not create an adequate electrical connection. Therefore, it is important
in the formation of the twist pins 50 that the bulges 58 be separated
by predetermined intervals 76 (FIG. 1) along the length of the wire 52.
The position of the bulges 58 and the length of the intervals 76
depend on the desired spacing between the printed circuit boards 62 of the
module 64. The amount of bending of each of the outer conductors 54
at each bulge 58 must also be controlled so that each of the bulges 58
exercises enough force to make good electrical contact with the vias. Moreover,
the amount of outward deflection or bulging of each of the bulges 58 must
be approximately uniform so that none of the bulges 58 experiences permanent
deformation when the bulge is pulled through the vias. Distortion-induced disparities
in the dimensions of the bulges adversely affect their ability to make sound electrical
connections with the vias 60. Further still, each twist pin 50 should
retain a coaxial configuration along its length without slight angular bends at
each bulge and without any bulge having asymmetrical characteristics. The coaxial
configuration facilitates inserting the twist pin through the vertically aligned
vias, maintaining the resiliency of the bulges, and establishing good electrical
contact with the vias.
The requirements for close tolerances and precision in the twist pins are made
more significant upon recognizing the very small size of the twist pins. The typical
sizes of the most common sizes of helically-coiled wire are about 0.0016, 0.0033
and 0.0050 in. in diameter. The diameters of the strands 54 and 56
used in forming these three sizes of wires are 0.005, 0.0010, and 0.0015 in., respectively.
The typical length of a twist pin having four to six bulges which extends through
four to six printed circuit boards will be about 1 to 1.5 inches. The outer diameter
of each bulge 58 will be approximately two to three times the diameter of
the regularly stranded wire in the intervals 76. The tolerance for locating
the bulges 58 between intervals 76 is in the neighborhood of 0.002
in. The weight of a typical four-bulge twist pin is about 0.0077 grams, making
it so light that handling the twist pin is very difficult. Handling each twist
pin is also complicated because its small dimensions do not easily resist the forces
that are necessary to manually manipulate the twist pin without bending or deforming
it. It is not unusual that a complex 4 in.×4 in. module 64 may require
the use of as many as 22,000 twist pins. Thus, the relatively large number of twist
pins necessary to assemble each three-dimensional module require an ability to
fabricate a relatively large number of the twist pins in an efficient and rapid manner.
A general technique for fabricating twist pins is described in the three previously-identified
U.S. patents. That described technique involves advancing the length of the stranded
wire, clamping the stranded wire above and below the location where the bulge is
to be formed, fusing the outer strands of the wire to the core strand of the wire
preferably by laser welding at the locations above and below the bulge, and rotating
the wire between the two clamps in an anti-helical direction to form the bulge.
In a prior art implementation of this twist pin fabrication technique, a wire
feeder advanced an end of the helically stranded wire which was wound on a spool.
The wire feeder employed a lead screw mechanism driven by an electric motor to
advance the wire and unwind it from the spool. A solenoid-controlled clamp was
connected to the lead screw mechanism to grip the wire as the lead screw mechanism
advanced as much of the stranded wire from the spool as was necessary for use at
each stage of fabrication of the twist pin. To advance more wire, the clamp opened
and the lead screw mechanism retracted in a reverse movement. The clamp then closed
again on the wire and the electric motor again advanced the lead screw mechanism.
While this prior art wire feeder mechanism was functional, the reciprocating
movement of the feeder mechanism reduced efficiency and slowed the speed of operation.
Half of the reciprocating movement, the return movement to the beginning position,
was wasted motion. Moreover, the relatively high inertia and mass of the lead screw,
clamp and motor armature required extra force and hence time to execute the reversing
movements necessary for reciprocation. Furthermore, the rotational mass of the
wire wound on the spool limited the acceleration rate at which the lead screw could
unwind the wire off of the spool. The rotational mass was frequently sufficient
enough to cause the wire to slip in the clamp carried by the lead screw. Slippage
at this location resulted in the formation of the bulges at incorrect positions
and incorrect lengths of the leader 68 and the internal lengths 76.
The desire to avoid slippage also limited the operating speed of the fabricating equipment.
The prior art bulge forming mechanism included two clamping devices which closed
on the wire above and below at the location where each bulge was to be formed.
The clamping devices held a wire while a laser beam fused the outer strands 54
to the center core strand 56 at those locations. Thereafter, the lower clamping
device was rotated in an anti-helical direction while the upper clamping device
held the wire stationary, thereby forming the bulge 58.
The lower clamping device was carried by a sprocket, and the wire extended through
a hole in the center of the sprocket. A first pneumatic cylinder was connected
to the clamping device to cause the clamping device to grip the wire. A chain extended
around the sprocket and meshed with the teeth of the sprocket. One end of the chain
was connected t
