CA1324686C - Twisted wire jumper electrical interconnector - Google Patents
Twisted wire jumper electrical interconnectorInfo
- Publication number
- CA1324686C CA1324686C CA000616409A CA616409A CA1324686C CA 1324686 C CA1324686 C CA 1324686C CA 000616409 A CA000616409 A CA 000616409A CA 616409 A CA616409 A CA 616409A CA 1324686 C CA1324686 C CA 1324686C
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- Prior art keywords
- jumper
- wire
- coil
- strands
- bulged
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A method and apparatus for interconnecting electronic circuit boards through the use of twisted wire jumpers which are formed from multi-filament wire and which have enlarged bird cages formed along the pins. The pins are drawn through n stack of circuit boards to position the cages in contact with interconnection apertures located in the printed circuit boards. The frictional engagement of the cages in the apertures provides both electrical inter connection of, and mechanical coupling between the printed circuit boards.
A method and apparatus for interconnecting electronic circuit boards through the use of twisted wire jumpers which are formed from multi-filament wire and which have enlarged bird cages formed along the pins. The pins are drawn through n stack of circuit boards to position the cages in contact with interconnection apertures located in the printed circuit boards. The frictional engagement of the cages in the apertures provides both electrical inter connection of, and mechanical coupling between the printed circuit boards.
Description
Twi~ted ~ire Ju~per 81eetrical Intereonneetor TECHNICAL FIELD OF THE INVENTION
The present invention relates to the field of electrical circuit connector6, ~nd more spec$fically to both an apparatus and a method for intereonnecting ~tacks of p~inted circuit boards.
BACRGROUND OF THE INVENTION
Integrated eireuits are typically fabrieated on wafer~ which ~re then eut up to form individual integr~ted eircuit~. The6e individual circuits are packaged within hexmetically 6ealed eeramic or plastie paekages. The 6ignal and power lines from the integrated eireuit are brought out to the pln~ of the paekage by means of leads attached to bondinq pads on the integrated cireuit ehips.
The ehips are then used to form larger circuit~ by interconnecting the integxated eircuit p~ckages by mean~ of prlnted eireuit bo~rds. These eircuit boards may contain several layers of electrical intereonnect. Typieally the $ntegrated cireuit paekages are aoldered to the eireuit board. The solder$ng process forms an elecitrical and mechanical connection batween the integr~ted circuit package and the circuit board.
To form still larger eireuit6 called modules, circuit boaxds may be arranged and interconnected in a variety of ways. One popular high density interconnect scheme is to stack the circuit boards in a sandwiched relationship and electrieally interconnect the eircuit -" I 324686 boards with ~umpers passed through the stack ~long the Z
axi~. Thi6 packing ~cheme ~chieves a relatively hiqh packing den ity ~imited by heat di6~ipation ~nd connector spacin~ requirements.
S The aforementioned technique of forming larger circuit6 by u6ing individually pack~ged integrated circuits mounted on circuit board~ limits packing density. The actual integrated circuit chip~ themselve~ are typlcally smaller than one-tenth of a ~guare inch, and only cover only 10-20 percent of the board area. Due to the low density achieved through the use of individually packaged integrated circuit chips and traditional interconnection technology, it is difficult to increase the operating speed of the system. Additionally, the inter-board spacing of ~tacked circuit boards is limited by the height of the integrated circuit packages ~nd the inter-board connects.
This limits packing den~ity in the z direction ~8 well.
Configuratlons which li~it packing density limit the interboard signal speed due to the long propagation delays ~seociated with the long interconnect lines.
Another problem presented by traditional configurations relates to the ease with which modules csn be disassembled. Forms of construction which involve soldering and ~taking of the board assemblies typicall~
re~ult in modules which cannot be disassembled or repaired.
The present invention provides ~ new apparatu~ and method for high-density interconnects of circuit boards which overcomes these disadvantages of the prior art.
SUMNARY OF THE INVENTION
The present invention provides for the interconnection of sandwiched circuit board~ through the use of twisted wire ~umper connectors installed in interconnection apertures of circuit boards.
The circuit boards disclo~ed for use with this invention have the integr~ted circuit chips attached directly to the printed circuit without the tradit~onal ceramic or plastic packaging. ~he circuit boards them~elves are manufactured with plated- through hole~, having hole S patterns 6ubstantially matching the bonding pad patterns of the integrated circuit chips.
The integrated circuit ch~ps are manufactured with flying leads which are positioned facing the circuit board.
The flying leads are ~nserted through the plated holes so that the flying leads protrude from the circuit board.
Caul plates are then poRitioned on the outer sides of this sandwich and pressed together ~o that the 6ticky or soft gold of the flying leads is compres~ed within the pl~ted holes, causing the soft gold to deform against the 6urface of the plated holes and thereby forming a strong electrical and mechanical bond. The caul pl~tes are then removed and the integrated circuit package remains firmly attached to the circuit board. Thi~ results in improved packing density of integrated circuit chip~ on circuit boards.
Two or more ~tacked circu$t bohrds are interconnected using electrically conductive tw$sted wire ~umper connectors or ~umpers inserted into the plated-through hole~ of the stacked circuit boards. The twisted wire ~umper connectors are made from multi-filament wire and have enlarged portions called bird cages, formed along their length. Thes~e bird cages bow out to a large outer radius, which ~ larger than the inner radius of the plated-through holes of the printed circuit boards. The twi~ted wire ~umper connectors are used as inter board ~umpers for the tran~mis6ion of power or logic 6ignals. The ~umpers are preferably drawn through the stacked circuit board~ through the use of a leader. The wiping action of the insertion create~ ~ low impedance electrical connection between the circuit bosrd~. The twisted wire ~umper connector is made slightly longer than the stack height of the module 80 that a portion of the twisted wire ~umper connector protrude6 through one or both side6 of the ~andwich of circuit boards forming a ~tub. This stub may then be used to a6Ri6t in the removal of the twi~ted wire jumpers to facilitate module repair.
Thus in connection with thi6 divisional specification the present invention provides a twisted wire jumper for interconnecting electronic assemblies comprising:
a plurality of cylindrical portions, each comprising;
a central core strand;
a helically wound, multiple 6trand coil sheath surrounding said central core strand; and a plurality of connector portions, each comprising;
a plurality of resilient strandc forming a barrel shaped cage for connection with said electronic assemblies.
In another a6pect the invention provides a twisted wire jumper for interconnecting electronic assemblies having interconnection apertures comprising:
a central core strand;
multi-fil~ment coil strands ~urrounding said core strand, forming a plurality of bulged cages for resilient frictional engagement of ~aid interconnection apertures,providing electrical interconnection and releasable mechanical connection between said assemblies.
- ` 1 324686 -In a further a~pect the invention provides a twisted wire jumper for interconnecting electronic a~emblie~, which hAve ~nt~rconnection apertures, compri~ing:
a central core strand having ~ head portion ~nd having a tail portion;
a helically oriented coil ~urrounding said core ~trand, wound to form a 6equence of bulged cages for resilient frictional engagement of sa$d interconnection apertures, providing electrlcsl interconne~tion and rele~sable mechanical connection between said assemblie~,and wound to form a seguence of cylindric~l sections for the electrical coupling o$ said bulged cage6 and for the mechanical support of said bulged cages.
In another embodiment this divisional specification provides a method of manufacturing a twisted wire jumper contact comprising the steps of:
clamping a wire to place it under tension;
melting said wire to form a blunt nose;
crimping said wire at first and ~econd locations to form a pair of crimp collars;
rotating said wire in an anti-helical direction to form a bulged cage section between said collars;
releasing sa~d wire;
advancing said wire to form a cylindrical section.
In still another embodiment this invention provides an elongated ~umper for interconnecting a plurality of electronic assemblies, comprising a plurality of cylindrical portions and a plurality of connector portions separated by a cylindrical portion along the length of the ~umper, wherein:
-4a-each of the plurality of cylindrical portions comprises:
a central core strand;
a helically wound, multiple strand coil sheath surrounding said central core strand; and each of the plurality of connector portions comprise~:
a plurality of resilient strands forming a barrel shaped cage extending transversely outward a greater distance than the sheath of an adjacent cylindrical portion, the barrel shaped cage adapted for connection with said electronic assemblies.
In still a further embodiment the invention provides a method of manufacturing an elongated twisted wire jumper from a wire formed by a plurality of helically wound strands, compri~ing the steps of:
clamping said wire to place it under tension:
melting said wire to form a blunt nose;
crimping said wire at first and second locations to form a pair of crimp collars;
rotating said wire in an antihelical direction to form a bulged cage section between said collars;
releasing said wire;
advancing said wire to form a cylindrical section.
~RIEF DESCRIPTION OF THE DRAWINGS
In the drawings like numerals $dentify like components throughout the several views.
FIG. 1 i~ a side view of an integrated circuit die onto which flying gold leads are ball bonded and 6traightened by a ball bonding machine.j FIG. 2 8hows the ~ix step6 that the flying lead ball bonder performs in order to attach a flying lead to an integrated circuit die.
FIG. 3A show6 the bonding pad pattern on a typical integrated circuit.
FIG. 3B ~hows the corresponding plated-through hole pattern on a circuit board which mates the integrated circuit chip onto the circuit board.
-4b-FIG. 4 shows the relative positions of the integrated circuit chip and the circuit board prior to compression of the flying leads into the plated holes.
FIG. 4A is a closeup view of the relative positions of the integrated circuit chip and the circuit board prior to compression of the flying leads into the plated holes.
FIG. S ~hows the relative positions of the integrated circuit chip and the circuit board after the flying leads have been compressed inside the plated holes of the circuit board.
FIG. 5A i8 a closeup view of a ball-bonded flying lead that has been compressed into a plated-throuqh hole on the circuit board.
FIG. 6 is a ~ide view of the compression process ~4c-wherein a plurality of integrated circuit chip~ hav~ng flying leads ~re att~ched to ~ sin~le printed circult board through the application of ~eating force on c~ul plates which sandwich the circuit board/chip combination.
FIG. 7 shows a plated-through hole pattern for a typical board onto which integrated circuit dice are nttached in the preferred embodiment of the present invention.
FIG. 8 ~hows a module ~ssembly having a plurality of circuit b~ards nested together.
FIG. 9 is a side view of the module assembly of Fig. 8 showing the det~ils of the logic ~umpers and power ~umpers for logic and power interconnection between the stacked ~andwich a~sembly of printed circuit boards.
FIG. lOa shows the twisted wire ~umper logic ~umper or connector.
FIG. lOb 6hows the twisted wire ~umper power ~umper or connector.
FIG. lOc depicts a cross section of the wire used to form a twi~ted wire ~umper connector.
FIG. lOd depicts a cross ~ection of a bird cage formed in a twisted wire ~umper connector.
FIG. lOe shows a cross section of a crimp in the wire.
FIG. 11 shows a cross-sectional view of ~ single twisted wire ~umper logic ~umper that has been installed through axially aligned plated-through holes of a st~ck of printed circuit boards of the module assembly of Fig. 9.
The f$gure is 8hown in an exaggerated scale to clarify the operation of the invention.
FIG. 12 iS acros~-section~l view of a single twisted wire ~umper power ~umper that has been installed through the axially aligned plated-through holes of the ~tacked~array of printed circuit boards of the module 1 324~86 as6embly of Fig. 9. The figure i~ ~hown in ~n exaggerated scale to clarify the operation of the ~nvent~on.
FIG. 13 is a 6ide view of mechanical 6chematic which ha6 been greatly exagger~t~d to show a 6ingle S twi6ted wire jumper compensating for the mi6alignment of a ~tack of printed circuit boards.
FIG. 14 6how6 ~ method for in~talling twi~ted w~re ~umper connectors into a stack assembly of four printed circuit boards.
FIG. 15 6how~ the method of manufacturing twi6ted wire ~umper connectors.
FIG. 16a showE an slternate form of a twi~ted wire ~umper.
FIG. 16b 6hows a cross ~ection of the twisted wire jumper shown in FIG. 16a.
FIG. 16c shows a cross section of the twisted wire jumper shown in FIG. 16a.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODINE_ The preferred embodiment of the present invention involves the high-density packing of 6ilicon or gallium srsenide (GaAs) integrated circuit chips onto ~ingle-layer or multi-lsyer interconnect printed circuit bosrds. The circuit boards have plated-through holes or interconnection apertures which permit the hiqh-density packing of circuit bosrds in a sandwiched arrangement. The application of this technology permits improved speed, improved hest dissipation, and improved packing density required for modern ~upercomputers such ~s the Cray-3 manufactured by the as6ignee of the present invention.
' In the preferred embodiment of this application, the integrated c$rcuit chips are att~ched to the circuit board by flying yold leads, ~8 discussed below and disclosed in Canadian application Serial No. 567,0a4 5 which i6 ~s~igned to the 6ame assignee of the present invention. By placing the integrated circuits directly on the circuit, the bulky packaging normally found on inteqrated circuit~ is elimina~ed.
Fl~inq Lead Construction FIG. 1 ~hows the preferred embodiment for attaching the flying gold leads to the 6ilicon or gallium arsenide packaged chip or die before attachinq the die to the circuit board. The leads ar0 made of soft gold wire which is approximately 3 mil6 in diameter. The GaA~ chips u~ed in the preferred embodiment contain 52 bonding pads which have a sputtered soft gold finish. The ob~ective of the die bonding operation is to form a gold-to-gold bond between the wire and the pad. A Hughes automatic thermosonic (gold wire) ball bonding machine Model 2460-II
may be modified to perform this operation. Thi~ machine is available from Hughes ~ool Company, Los Angeles, California. This machine wa8 designQd and normally used to make pad-to-lead frame connections in IC packages and ha~
been modified to perform the step~ of flying lead bonding a~ described below. The modifications include hardware and software changes to allow feeding, flaming off, bonding and breaking heavy gauge gold bonding wire (up to 0.0030 dia.
Au wire).
The Hughe~ automatic b~ll bonding machine ha~ an X-Y positioning bed which is used to posltion the die for bonding. The die is loaded on the bed in a heated ~acuum fixture which holds up to 16 dice. The Hughes bonding machine i~ aquipped with a vi~ion system which can recognize the die patterns without human intervention and position each bonding pad for proce~slng.
The soft gold wire thst i~ used for the flying leads in the preferred embodiment of the pre~ent invention S is sometimes referred to ~s sticky gold or tacky gold.
This gold bonding wire i~ formed from a 99.994 high-purity ~nnealed gold. The process of annealing the h$gh-purity gold results in a high elongation (20-25~ ~tabilized and ~nnealed)~ low tensile strength (3.0 mil., 50 gm. min.) gold wire which is dead ~oft. The wire composition (99.99%
pure Au non-Beryllium doped) i~ ns follows:
Gold 99.990% min.
Beryllium O.002% max.
Copper 0.004% max.
Other Impurities (each) 0.0034 max.
Total All Impurities 0.010% max.
This type of gold i8 available from Hydrostatics (HTX
grade) or equivalent.
Referring to FIG. l, the flying lead die bonding procedure begins with the formation of a soft gold ball 106 at the tip of the gold wire 101. The wire i8 fed from a supply spool (not shown) through a nitrogen-filled tube lO9 (shown in FIG. 2) to a ceramic capillary 100. The inside of the capillary is ~st 61ightly l~rger than the wire di~meter. The direction of nitrogen flow in the connecting tube 109 can be altered to drive the wire either toward the die or toward the supply spool. Thi~ allows the gold wire to be fed into or withdrawn from the capillary t$p.
The gold ball 106 formed at the end of the gold wire 101 i6 thermo60nically bonded to bonding pad 105 of chip 104. The capillary tip 102 of capillary 100 is capable of heat$ng the ball bond to 300C concurrent with pressing the ball 106 onto the pad 105 and ~onically 1 3246~6 vibrating the connection until a etrong electrical snd mechanical connection i8 formed. The cspillary 100 $8 then withdrawn from th0 ~urface of the die 104 and tho wire 101 is extruded from the tip 102. A notching mechanism, added to the Hughes ball bonder to perform the specific notching operation described herein, i5 used to make ~ notch 107 at the appropriste height, thus defining the length of the flying lead. The wire clsmp lOB grasps the gold wire 101 ~nd the capillary i8 withdrawn upward, breaking the flying lead at 107 ~nd concurrently performing a nondestructive test of the ball bond to bonding pad connection and slso straightening and stiffening the flying lead.
The sequence of steps required to make a flying lead bond to the package die i6 6hown in FIG. 2. Step 1 begins with the feeding of a predetermined amount of wire through the capillary 100. A mechan~cal arm then po~itions an electrode 114 below the capillary tip 102 and a high-voltage electrical current forms an arc which melt6 the wire and forms a gold ball with a diameter of approximately 6 mils. This operation is called electrostatic flame-off (EFO). Ball size is controlled through ad~ustment of the EFO power supply output. During this step, the cl~mp8 108 are closed and the nitrogen drag is off. This action occurs above the surface of the integr~ted circuit chip BO ns to avoid any damage to the chip during the EFO ball forming process.
In step 2, the nitrogen drag 109 withdraws the supply wire 101 into the capillary 100 and tightens the ball against the capillary t$p 102.
The capillary tip 102 is heated to approximately 200C to assist in keeping the gold wire 101 in a malleable state. The die fixture is also heated to 200C
to avoid wire cooling during the bonding process. The die fixture i8 made of Teflon*-coated aluminum. Teflon is a trademark for polytetrafluoroethylene. As shown in *Trademark 9 FIG. 1, a vacuum cavity or vacuum plate 103 hold5 the die 104 in position on the fixture during the bondin~ process.
In ~tep 3, ~he bonding mschine lower~ the capillary 100 to the surface 105 of a bonding pad and applies high pre6sure (range of 30-250 gram~) to the trapped gold ball 106 along with ultraqonic vibration at the capillary tip 102. The capillary t$p 102 i3 flat, with a 4-mil inside diameter and an B-mil out~ide diameter. ~he ball 106 i6 flattened to about a 3-mil height and a 6-mil di meter. ~ltra~onic energy is supplied through the ceramic capillary 100 to vibrate the gold ball 106 and scrub the bonding pad surface. The sound i8 oriented 80 that the gold ball 106 moves psrallel to the die ~urface.
The Hughes ball bonding machine has the ability to vary the touch-down velocity, i.e., soft touch-down for bonding GaAs, which i8 program selected. The ultrasonic application is also program selected.
In step 4, the capillary 100 is withdrawn from the surface of the die 104, extending the gold wire 101 as the head is raised. The nitrogen drag is left off and the capillary is raised to a height to allow enough gold wire to form the flying lead, a tail length for the next flying lead, and a ~mall amount of clearance between the tail length and the capillary tip 102. The Hughes ball bonder device is capable of sQlecting the height that the capillary tip can move up to a height of approximately 0.750 inch.
In 6tep 5, ~n automatic notching m~chanism 115 moves into the area of the extended qold wire 101 and strikes both sides of the wire with steel blades. This is e~sentially n scis~or action which cuts most of the way through the gold wire 101, forming a notch 107 (F~G 1). me notch 107 is made 27 mils above the surface of the die The notching mechanism has been added to the Hughes ball bonder for the precise termination of the flying leads. The Hughes ball bonder has been modified to measure and display ~ 32~686 the notch mechanism height. The activation signal for the notch mechanism iB provided by the Hughes ball bonder system for the proper activation during the sequence of ball bonding. The flying lead length i8 ad~ustable from between 0.0 mils to 50.0 mil6. It will be appreciated by those 6killed in the art that the notching function can be accomplished with a variety of ~echani~ms 6uch as the scissor mechanism di6closed above, a hammer-anvil system, and a variety of other mechanisms that merely notch or completeiy sever the wire 101.
In step 6, clamp 108 closes on the gold wire 101 above the capillary 100 and the head i~ withdrawn until the gold wire breaks st the notched point. This 6tretching process ~erves several useful purposes. Primarily, the gold wire is straightened by the stretching force and stands perpendicular to the die 6urface. In addition, the bond is non-destructively pull-tested for adhe~ion at the bonding pad. The lead 101 is terminated at a 27-mil height above the die ~urface 104 in the preferred embodiment. At the end of step 6, the capillary head for the bonding mechanism is positioned over a new bonding pad and the process of steps 1-6 begins again. The bonding wire 101 is partially retracted into the capillary once again, and the clamps are closed, as shown in 6tep 1, 60 that a new ball may be formed by the EF0.
The die positions are roughly determined by the loading po~itions in the vacuum fixture. The Hughes automatic bonding mschine is able to ad~ust the X-Y table for proper bonding position of the individual die. An angular correction i~ automaticnlly made to ad~ust for tolerance in placing the die in the vacuum fixture. This i8 done through a v$sion sy~tem which recognizes the die pad configurations. Using the modified Hughe~ automatic bonding machine with the current bonding technique, a minimum bonding rate of 2 die pads per ~econd is possible.
Circuf t Board Con~truction Once the gold bonding leads are attached to the inte~rated circuit chip or die, the die 18 ready to be ~ttached to the circuit board. As shown in FIG. 3A, the bonding pattern of the integrated circuit die 104 matchec the plated hole pattern on the circuit board 110,~hown in FIG.3B. For example, the top view of integrated circuit die 104 in FIG. 3A shows the bonding pad 105 in the upper right corner. The circuit board 110 shown in FIG. 3B shows a corresponding plated hole 111 which i6 aligned to receive the b~ng lead ~rcm box~ng pad lO5 (shcwn in FIG. 3A) when circuit b~
110 is placed over integr~ted circuit 104 and the flying leads are inserted into the hole pattern on the circuit board. Thus, each bonding pad of integrsted circuit 104 has a corresponding plated hole on circuit board 110 aligned to receive the flying leads.
The circuit board assQmbly operation begins with the insertion of the die into the circuit board. The circuit board is held in a vacuum fixture during the inser-tion process to make sure that the board remains flat.
Insertion can be done by hend under ~ binocular microscope or production assembly can be done with a pick-and-place machine.
Referring to FIG. 4, the circuit board 110 with the loo~ely placed~diQ 104 is mounted on an ~luminum vacuum caul plate (lower c~ul plate) 113. Steel guide pins (not shown) are placed in corner holQs of the circult board to prevent board motion during the assembly operation. A
second (upper) caul plate 112 is then pl~ced on the top ~ide of the circuit board populated with chips to press again~t the tops (non-pad side) of the chips 104. The sandwich assembly comprising the circuit board, the chip and the c~ul plates i8 then placed in a press and pressure i6 applied to buckle and expand the gold le~ds 101 in the plated hole~ 111 of the circuit board.
The 6ide v~ew of the sandwiched circuit board 110, integrated circuit chip 104, ~nd c~ul pl~tes 112 ~nd 113 in FIGS. 4 and 5 illustrates the position of the gold leads 101 before and after the pressing operation, respectively.
In the preferred embodiment there iB a 9-mil exposure of gold lead 101 of a total lead length of 29 mil~ which upon compression will buckle and expand into the plated hole 111 of the circuit board 110. The 3-mil diameter wire 101 in a 5-mil diameter hole 111 means the initial fill i~ 36 percent of the available volume. After pressing, the fill ha6 increased to 57 percent as a result of the 9.2-mil shortening of the gold lead 101. As shown in greater detail in FIGS. 4a and Sa, the lead typically buckles in two or more places, and these corners are driven into the sides of the plated hole 111 of the circuit board. The integrated circuit pad 105 i8 electrically connected to the flying lead by the ball bonding proce~s. The flying wire also electrically connects the integr~ted circuit to the circuit board through the pressing operation.
The circuit board 110 may be removed from the press with the integrated circuit chip 104 securely attached and electrically bonded to the plated holes of the circuit board.
FIG. 6 sh,ows a view of the circuit board press which is used to attach the integrated circuits to the printed circuit board. The upper caul plate 112 iB a Teflon-coated seating c~ul plate which iB aligned through alignment pins 114 with the circuit board 110 and the lower caul plate 113 which is a vacuum caul plate to hold the circu~t board flat during the pressing procQss. The alignment pins 114 are used to prevent the printed circuit board 110 from ~liding or otherwise moving during the pressing process. A seating force is ~pplied to the top of upper caul pl~te 112 which forces the excess flying lead material into the plated holes of printed circuit board 110. Thus, integrated circuits 104 are mechanically and electrically bonded to printed circuit board 110.
It will be ~ppreciated by tho~e ~kill~d ln the art that many variations of the above-described pressing operation can be used which results in the ~me or oquivalent connection of the flying lead~ to the circuit boards. For example, the flying leads of the chips could be completely in~erted into the through-plated holes of the circuit board prior to the pressing operation with the excass gold leads p~otruding out the opposlte ide. The first caul plate could then be used to hold the chip onto the circuit board while the second c~ul plate is used to compress the leads into the holes.
Module AssemblY Construction FIG. 7 shows an ex~mple of a printed circuit board hole pattern for the circuit boards u6ed in the Cray-3 computer manufactured by the assignee of the present invention. In the preferred embodiment of the present invention, each circuit board provides 16 patterns of plated-through hole~ for receiving the flying leads of 16 integrated circuits. The 16 integrated circuits are ~tt~ched to the circuit board ~hown ~n FIG. ? through the pre~sing process previously described. Each aperture pattern on the circuit board 110 corresponds to the contact pad pattern shown on FIG. 3, from which the bonded flying leads extend outward as shown in FIG. 4.
Each corner of circuit board 110 has a group bf four plated-through holes 304 which are used for alignment during initial assembly. These apertures 304 are also used for power distribution in the completed module.
In the preferred embodiment of the present invention, 16 circuit boards 110 of the type shown in FIG. 7 are stacked together to form a module assembly 200 as - 1 3246~6 shown in both FIG. 8 and FIG. 9. The circuit boards 110 ~re arranged in n 4 x 4 matrix on each of four layers, creating an X-Y-Z matrix of 4 x 4 x 4 circuit board~.
Therefore, each module assembly 200 has 64 circuit boards containing 16 integrated circuit chips each, ~iving a total of 1,024 integrated circuit chips per module assembly.
In the preferred embodiment, the module assembly 200 is 4.76 inches wide, 4.22 inches long, ~nd 0.244 inch thick. As is shown in FIG. 8, ~t one edge of the module sssembly are four machined metsl power blade~ 201a-201d.
These power blades are used both for mechanical connection to the cabinet into which the module as6emblies are placed ~nd for electrical connection to the system power ~upplies.
At the opposite side of the module assembly are 8 edge connectors 202a-202h used to communicate with other modules. These connectors form the communication paths to the other module assemblies within the machine. The bundles of wires between the circuit boards of the module s6sembly 200 and the board edge connectors 202a-202h ~re 2U provided with strain relief member~ 240a-240h respectively.
Each strain relief is a plastic member which protrudes from the edge of the circuit boards. The interconnected wires pass through holes in the strain relief members between the circuit boards and the floating connectors 202a-202h. In this fashion, the flexing of the wlres during the connection and disconnection of connectors 202a-202h does not strain the soldered connection of the wires to the circuit boards. The strain relief members 240a-240h also serve a~ spacers between the circuit boards in a fashion s$milar to spacer6 203 described below. I
Electrical communication between the integrated circuit chips of each board 110 is accomplished by means of the prefabricated foil patterns on the surface and buried within each circuit board. The electrical communication between circuit boards 110 in the X-Y plane is by means of twisted wire jumpers 231 and 232 along the Z-axis (perpendicular to the planar surface of the circuit boards and the module assembly) effecting electrical connection between the circuit boards llO, two logic plates 216 and 217 sandwiched in the center of the module assembly 200 and a centrally located power distribution board 210 sandwiched between the logic plates, as shown in FIG. 9.
The z-axis twisted wire ~umper6 231 and 232 may be used for electrical communication signals and for power distribution. The Z-axis ~umpers may be placed in any of the area on circuitboards 110 that is not occupied by an integrated circuit.
In the preferred embodiment of the assembly module, anywhere from 200-1000 z-axis logic ~umper8 231 may be used for a single circuit board stack. 6400-11,000 ~umpers may be used for a module 200.
FIG. 9 shows a sectional view of a module assembly 200. In the preferred embodiment, module assembly 200 is constructed as a sandwich of a electronic assemblies. These assemblies include a plurality of populated circuit boards 212,214,219,221,which are spaced apart from each other using insulated spacers, such as the one illustrated at 203. Another example of electronic assemblies are the logic plates 216 and 217 which are in contact with and are axially aligned with a power plate 210. All of the circuit boards are orientated 80 that the flying leads of the integrated circuits 104 are away from the power plate 2L0. Also as shown in FIG. 9, power blade 201 abuts circuit boards 212, 214, 219, 221 and logic plates 216 and 217. Additionally, power plate 210 extends into power blade 201. FIG. 9 shows all ma~or component6 of a completely assembled module assembly 200 with the exception of the edge connectors which have been omitted for clarity.
All the electronic assemblies including the circuit boards and the logic plates 216 and 217 are designed 80 that when they are assembled into a module, 1 32~686 their plated-through holes become subQt~ntially aligned in the Z-axis, with the complimentary plated-through holes of the other circuit boards and logic plates.
The power plate 210 i~ designQd ~o that when it iR
~ssembled into a module, its larger unplated holes ~ubstantially align in the Z axis with the plated-through holes of the circuit boards and logic plates. Likewise, circuit boards 110 and power plates 210 sre designed so that when assembled in a module a~embly, their plated-through holes 304 become substantially aligned in the Z-axis with corresponding plated-through holes on other circuit boards and power plates.
However, logic plates 216 and 217 are designed so that when they are a~sembled into a module, their plated-through holes are sub~tantially aligned in the Z axi~ withthe plated-through holes 304 of the circuit boards and power plate.
Electrical communication between the integrated circuit chips on each board is accomplished in the X-Y
plane by means of prefabricated foil patterns on the surface of, and buried within, each circuit board.
Electrical communication between circuit boards 21~, 214, 219, 221 is routed via foil patterns buried within logic plate~ 216 and 217. Electrical inter-connect~ between circuit board~ 212, 214, 219, 221 and logic plates 216 and 217 are accomplished by inserted electrically conductive Z-nxis twisted wire ~umper log$c ~umpers 231 contacting logic plate interconnection apertures 303 on the circuit boards and logic plates.
As de~cribed in more detail below, the twisted wire ~umper logic ~umpers or connectors have wire bird-cage, or bulged portions that have a greater outer radius than the inner radius, or inner contact surface, of the complementary interconnection apertures shown as plated-through holes 303. When a twist-pin logic jumper 231 is inserted into the module assembly, the wire bird-cage portions compress against the plated-through holes 303 thereby forming low resistance connections.
Electrical power di~tribution to the integrated circuit chips on each board 110 i~ accomplished by means of prefabricated foil pattern~ on the surface of, and buried within, each circuit board 110. Electrical power is di~tributed to circuit board~ 212, 214, 219, 221 through power plate 210 which connects to each of the power blades 201a-201d. Electrical powex inter-connections between circuit boards 212, 214, 219, 221 and power plate 210 are accomplished by inserted Z-axis twisted wire ~umper power jumpers or connectors 232. As described in more detail below, the twisted wire jumper power jumpers also have bulged portions, or wire bird-cages that, when compressed, have a greater outer radius than the inner radius, or inner contact surface, of the interconnection apertures represented by plated-through holes 304. When a twist-pin power jumper 232 is inserted in the module assembly, the wire bird-cages compress against the plated-through holes 304 thereby forming low impedance connections.
In the preferred embodiment, module assembly 200 i8 stacked with other module assemblies in a fluid cooling tank and po~itioned ~o that the planar surfaces of the module assembly are stacked vertically. Thus, in the preferred embodiment, FIG. 9 i8 a top-down look at module assembly 200. A type of cooling apparatus suitable for cooling the circuit board module assemblies of the present invention i8 described in V. S. Patent No.i4,590,538.
Cooling channels 230, a8 shown in FIG. 9, are provided to allow the cooling fluid to rise through the module assembly to remove the heat produced by the integrated circuits 104. Heat transfer occurs between circuit boards 1 through 4 (levels 212, 214, 219, and 221 respectively) and the cooling fluid in channels 230.
Cooling channels 230 are created by spacing the circuit boards populated with integrated circuit~ 104 from one another and from the logic plates using the above mentioned insulated spacer6 203. The insulated spacers 203 are held in place by twisted wire ~umper power ~umpers 232 during module assembly.
Twist-Pin Connectors FIG. lOa ~hows a single logic twisted wire ~umper connector for coupling logic level signals between the various electronic assemblies. The preferred embodiment of the twisted wire ~umper shown in FI;G. lOa includes a leader section 260, and a cylindrical tail section 261. Six bird cages 300 are formed between the crimps shown on logic jumper 231. It is preferred to weld the ends of the twisted wire jumper to form blunt nose sections as shown by weld 306. The leader 260 and the tail 261 may beyond the module assembly after insertion to assist in both installation of the twisted wire jumper connector and its removal during module disassembly. At each end of the connector a laser weld 306 is used to keep the wires making up the twisted wire jumper connector 231 from unravelling. The crimps 302 are used to form the wire bird cages 300. The crimps 302 and cages 300 are spaced along the twisted wire jumper to match the interboard spacing. It has proved desirable to extend the cages beyond the edges of the plated-through apertures in the printed circuit boards. For the Cray-3 product this has resulted in .028 inch crimp spacing. The 8iX bird cages 300 are made as described below.
Refer to FIG. lOc. The preferred embodiment the logic twisted wire ~umper 231 is m~de from seven strand multi-filament Be/Cu wire tempered to either 1/4 or 1/2 hard. It is preferred to u~e w~re with uniform ~trand diameters of approximately l.S to 1.6 mils in diameter. It ---` 1 324686 iB al80 preferred to use a nickel flashed, 30 microinch gold plated, beryllium copper alloy 25 CDA wire available from California Fine Wire Co.and other vendors. The ~even strands ~re configured ~ a ~ix around one helix. The wire diameter i8 approximately 4.8 mils before the bird cages 300 ~re formed. Refer to FIG. lOd. The bird cages 300 bulge outw~d to an outer radius of approximately 8.0 mils.
Refer to FIG. lOe. In the preferred embodiment, the individual ~trands making up the wire are fused toyether during the crimping operation.
FIG lOb show6 a ~ingle power twisted wire ~umper connector for coupling power to the various electronic assemblies. In the preferred embodiment the power twist- -pin ~umper has a leader section 262, a tail ~ection 263, ~n~ a n~t~r of crimp6 302 fon~ug five wire bind cages 301. The leader 262 and tail 263 may extend beyond the module a66embly to assist in installation and remov~l of the twi~ted wire ~umper connector. At each end of the connector there i6 a weld 307 to keep the wires making up the twisted wire ~umper connector from unraveling.
The 5 bird cages 301 are ~paced 60 that each bird cage substantially aligns with a corresponding power plated-through hole 304 of the module assembly 200.
Refer now to FIG. lOc. In the preferred embodiment the power twisted wire ~umper 232 i8 made from seven 6trands of either 1/4 or 1/2 ~ard, .0048 mil diameter, nickel flashed, 30 microlnch gold plated, beryllium copper alloy 25 CD~
wire. Ihe multi-fil~t wire is wo~d six an~d one (FIG. lOc) in a left handed helix. At pre~ent the preferred wrap i8 30 turn~ per inch. The wire diameter i8 approximately 14.4 mils before the bird cages sre formed~ Refer now to FIG.
lOd. The bird cages bulge outward to an outer radius of approximately 16.0 mils.
~ 20 Refer to FIG. lOe. In the preforred embodiment, the individual ~trand~ making up the wire are fused together during the crimping operation.
FIG. 11 show6 a cut-away view of a single logic 5 twisted wire ~umper in~talled in a module a~embly. The bird cages 300 compress again~t the plated-through holes 303 forming low impedance electrical connections. The leader 260 ~nd tail 261 extend beyond the module a~sembly to assi6t in module disassembly. Also ~hown are conductive paths 400 connected to circuit boards 212, 214, 219, and 221 for logic level routings to integrated circuit6 104.
In addition to the cylindrical leader and tail sections, one or a plurality of cylindrical intermediate sections 305 (Fig. lOa) connect the bird cages to one another at locations along the length of a logic or power jumper. The intermediate sections are of predetermined length sufficient to position the bird cages to align with corresponding plated-through apertures in the electronic as6emblies of the module assembly.
FIG. 12 shows a cut-away view of a 6ingle power twi6ted wire ~umper installed in a module assembly. The bird cages 301 compress against the plated-through holQs 304, forming low impedance electrical connections. The leader 262 nnd tail 263 extend beyond the module assembly to assist in module disassembly. Also shown are conductive paths 401 connected to circuit bo~rd~ 212, 214, 219, and 221 for power routings to in~egrated circuits 104.
-`-` 1 324686 Both ~umpers 231 nnd 232 are flexible and therefore can compensate for minor mi~alignment of a module assembly. FIG.13 shows a single power twisted wire ~umper in~talled in a misaligned module assembly which i~ depicted in greatly exaggerated form to clearly disclose this feature of the invention. The twisted wire ~umper flexes ~o that the bird-cages 301 compress against the plated-through holes 304 of the circuit boards 212, 214, 219, snd 221 and power plate 210. The logic twist-pin ~umper will similarly flex to compensate for module misalignment along any axis.
FIG.14 shows a method of in~erting the twisted wire ~umper connectors. A number of the electronic assemblies are stacked and aligned through the use of guide pins. The leader 262 of twisted wire ~umper 232 is inserted into the interconnection apertures 304 and passed completely through the stacked array. The leader is then grasped and drawn -2la--- 1 3246~6 through the stacked electronic assemblies until it i6 substantially completely through the assemblies. At this point each of the cages is drawn into engagement with the periphery of the various plated-through apertures. The leader is then cut off by a suitable cutter 800. A short stub 802 is left as an aid to the subsequent removal of the twisted wire jumper.
Fig. 15 shows a method of manufacturing the twisted wire jumpers in a preferred embodiment. In step 1, the wire is clamped between two feeder clamps 804 and 806. This operation places the wire under slight tension. Next a laser or other cut off device 808 is used to cut the wire by melting the wire. This operation forms a tip 810 on the wire which is an aid in threading the wire through the circuit board apertures. Next the wire is advanced to form the leader portion of the twisted wire jumper.
The formation of the bird cage structure 812 begins with the crimping operation shown in step 2. The purpose of the crimping operation is to join or fuse the strands of the multi-filament sheath together. This operation also results in the coupling of the outer sheath to the inner core wire as well. If the collar formed by the crimping operation rigidly joins the sheath to the core, the untwisting operation may result in a bird cage which has seven strands in the barrel shaped cage. This converts the wire from a six around one configuration to a seven around zero configuration. The six around one configuration is shown in Fig. 10c, which illustrates a cross section of the wire. The anti-helical twisting operation may displace the core from its center position, and force it into the cage structure.
In this instance the outer periphery of the cage is oomposed of seven strands, not six. The crimp portion 302 of a wire can be seen in Fig. 10e.
Typically two crimped collars are formed at a time. One of the crimping chucks is stationary and the other crimping chuck is rotatable. In step 3 the ., .
., .. . -. - ~, .
rotatable chuck is used to unwind the helical ~heath by rotating the collar in the anti-helical direction while the stationary crimping chuck keeps the wire from turning.
A~ present the preferred degree of rotation is 160 while rotations in the range of 100 to 180 appear to be ncceptable. This counter rotation increases the diameter of the twist wire connector ~nd farms a resilisnt bird cage structure 812 for frictional engagement with apertures of the electronic ~s~emblies, thu~ forming A connector portion.
In step~ 4 and S, once a bird cage i~ formed, the wire is advanced to the next position and the crimping operation i8 resumed to form the next bird cage.
After 811 of the bird cages are formed, the wire i~
advanced to the position shown in ~tep S. Laser 808 shears the tail and leaves a weld to keep the wires from unraveling. Additionally, the blunt end 810 of the next wire ~umper $8 formed. These operations are repeated to form the next twisted wire ~umper.
It is also contemplated to form the bird cages with the center core strand relatively free to absorb tension $orces resulting from the in~ertion of the twist wire ~umpers.
This structural relationship i~ achieved through the use of a laser weld which joins the o~r sheath stR~s 902 to each o~ A.
shown at 906, but rc~ to the center ccre stn~d 905 (FIGS. 16b and 16c).
mis form of co~uctian is shown in FIGS. 16a, 16b and 16c. In FIG.
16a laser weld6 9~0 are formed on the wire 903 through an operation performed by a laser such as that depicted as 808 ln FIG. 15. These laser welds are used to separate the bird cages 904 fro~ each other. In this embodiment the weld6 have a length of 3 to 6 mils while the bird cages themselves are about 28 mils long.
Refer to FIG 16b. The wire 903 i6 formed from six ~6) indiv$dual strands 902 of wire wrapped around a center conductor 905. Referring now to FIG. 16c, the laser weld 900 fuses the BiX outer ~trand~ 902 together, but not to ~he center conductor 905. The welded ~trands form a connection 905. The center conductor 905 c~n ~lide through the connection 906 under ten~ion.
It ~hould be appreci~ted that the crlmping fixtures show in thQ FIG. lS can al~o be adspted to fu~e the helical hheath str~nds to each other.
Those of ordinary skill in the srt will recognize that other types of wire may be u~ed in place of the wire described herein. For example, multi-~tranded wires which ~0 are made with differing strand alloys may be ~ubstituted.
While the present invention has described csnnection with the preferred embodiment thereof, it will be understood that many modifications will be readily ~pparent to those of ordinary skill in the art, and this application $~ intended to cover any ~daption or variations thereof. Therefore, it is manife6tly int~nded that thi6 invention be limited only by the cl~ims and the equivalents thereof.
The present invention relates to the field of electrical circuit connector6, ~nd more spec$fically to both an apparatus and a method for intereonnecting ~tacks of p~inted circuit boards.
BACRGROUND OF THE INVENTION
Integrated eireuits are typically fabrieated on wafer~ which ~re then eut up to form individual integr~ted eircuit~. The6e individual circuits are packaged within hexmetically 6ealed eeramic or plastie paekages. The 6ignal and power lines from the integrated eireuit are brought out to the pln~ of the paekage by means of leads attached to bondinq pads on the integrated cireuit ehips.
The ehips are then used to form larger circuit~ by interconnecting the integxated eircuit p~ckages by mean~ of prlnted eireuit bo~rds. These eircuit boards may contain several layers of electrical intereonnect. Typieally the $ntegrated cireuit paekages are aoldered to the eireuit board. The solder$ng process forms an elecitrical and mechanical connection batween the integr~ted circuit package and the circuit board.
To form still larger eireuit6 called modules, circuit boaxds may be arranged and interconnected in a variety of ways. One popular high density interconnect scheme is to stack the circuit boards in a sandwiched relationship and electrieally interconnect the eircuit -" I 324686 boards with ~umpers passed through the stack ~long the Z
axi~. Thi6 packing ~cheme ~chieves a relatively hiqh packing den ity ~imited by heat di6~ipation ~nd connector spacin~ requirements.
S The aforementioned technique of forming larger circuit6 by u6ing individually pack~ged integrated circuits mounted on circuit board~ limits packing density. The actual integrated circuit chip~ themselve~ are typlcally smaller than one-tenth of a ~guare inch, and only cover only 10-20 percent of the board area. Due to the low density achieved through the use of individually packaged integrated circuit chips and traditional interconnection technology, it is difficult to increase the operating speed of the system. Additionally, the inter-board spacing of ~tacked circuit boards is limited by the height of the integrated circuit packages ~nd the inter-board connects.
This limits packing den~ity in the z direction ~8 well.
Configuratlons which li~it packing density limit the interboard signal speed due to the long propagation delays ~seociated with the long interconnect lines.
Another problem presented by traditional configurations relates to the ease with which modules csn be disassembled. Forms of construction which involve soldering and ~taking of the board assemblies typicall~
re~ult in modules which cannot be disassembled or repaired.
The present invention provides ~ new apparatu~ and method for high-density interconnects of circuit boards which overcomes these disadvantages of the prior art.
SUMNARY OF THE INVENTION
The present invention provides for the interconnection of sandwiched circuit board~ through the use of twisted wire ~umper connectors installed in interconnection apertures of circuit boards.
The circuit boards disclo~ed for use with this invention have the integr~ted circuit chips attached directly to the printed circuit without the tradit~onal ceramic or plastic packaging. ~he circuit boards them~elves are manufactured with plated- through hole~, having hole S patterns 6ubstantially matching the bonding pad patterns of the integrated circuit chips.
The integrated circuit ch~ps are manufactured with flying leads which are positioned facing the circuit board.
The flying leads are ~nserted through the plated holes so that the flying leads protrude from the circuit board.
Caul plates are then poRitioned on the outer sides of this sandwich and pressed together ~o that the 6ticky or soft gold of the flying leads is compres~ed within the pl~ted holes, causing the soft gold to deform against the 6urface of the plated holes and thereby forming a strong electrical and mechanical bond. The caul pl~tes are then removed and the integrated circuit package remains firmly attached to the circuit board. Thi~ results in improved packing density of integrated circuit chip~ on circuit boards.
Two or more ~tacked circu$t bohrds are interconnected using electrically conductive tw$sted wire ~umper connectors or ~umpers inserted into the plated-through hole~ of the stacked circuit boards. The twisted wire ~umper connectors are made from multi-filament wire and have enlarged portions called bird cages, formed along their length. Thes~e bird cages bow out to a large outer radius, which ~ larger than the inner radius of the plated-through holes of the printed circuit boards. The twi~ted wire ~umper connectors are used as inter board ~umpers for the tran~mis6ion of power or logic 6ignals. The ~umpers are preferably drawn through the stacked circuit board~ through the use of a leader. The wiping action of the insertion create~ ~ low impedance electrical connection between the circuit bosrd~. The twisted wire ~umper connector is made slightly longer than the stack height of the module 80 that a portion of the twisted wire ~umper connector protrude6 through one or both side6 of the ~andwich of circuit boards forming a ~tub. This stub may then be used to a6Ri6t in the removal of the twi~ted wire jumpers to facilitate module repair.
Thus in connection with thi6 divisional specification the present invention provides a twisted wire jumper for interconnecting electronic assemblies comprising:
a plurality of cylindrical portions, each comprising;
a central core strand;
a helically wound, multiple 6trand coil sheath surrounding said central core strand; and a plurality of connector portions, each comprising;
a plurality of resilient strandc forming a barrel shaped cage for connection with said electronic assemblies.
In another a6pect the invention provides a twisted wire jumper for interconnecting electronic assemblies having interconnection apertures comprising:
a central core strand;
multi-fil~ment coil strands ~urrounding said core strand, forming a plurality of bulged cages for resilient frictional engagement of ~aid interconnection apertures,providing electrical interconnection and releasable mechanical connection between said assemblies.
- ` 1 324686 -In a further a~pect the invention provides a twisted wire jumper for interconnecting electronic a~emblie~, which hAve ~nt~rconnection apertures, compri~ing:
a central core strand having ~ head portion ~nd having a tail portion;
a helically oriented coil ~urrounding said core ~trand, wound to form a 6equence of bulged cages for resilient frictional engagement of sa$d interconnection apertures, providing electrlcsl interconne~tion and rele~sable mechanical connection between said assemblie~,and wound to form a seguence of cylindric~l sections for the electrical coupling o$ said bulged cage6 and for the mechanical support of said bulged cages.
In another embodiment this divisional specification provides a method of manufacturing a twisted wire jumper contact comprising the steps of:
clamping a wire to place it under tension;
melting said wire to form a blunt nose;
crimping said wire at first and ~econd locations to form a pair of crimp collars;
rotating said wire in an anti-helical direction to form a bulged cage section between said collars;
releasing sa~d wire;
advancing said wire to form a cylindrical section.
In still another embodiment this invention provides an elongated ~umper for interconnecting a plurality of electronic assemblies, comprising a plurality of cylindrical portions and a plurality of connector portions separated by a cylindrical portion along the length of the ~umper, wherein:
-4a-each of the plurality of cylindrical portions comprises:
a central core strand;
a helically wound, multiple strand coil sheath surrounding said central core strand; and each of the plurality of connector portions comprise~:
a plurality of resilient strands forming a barrel shaped cage extending transversely outward a greater distance than the sheath of an adjacent cylindrical portion, the barrel shaped cage adapted for connection with said electronic assemblies.
In still a further embodiment the invention provides a method of manufacturing an elongated twisted wire jumper from a wire formed by a plurality of helically wound strands, compri~ing the steps of:
clamping said wire to place it under tension:
melting said wire to form a blunt nose;
crimping said wire at first and second locations to form a pair of crimp collars;
rotating said wire in an antihelical direction to form a bulged cage section between said collars;
releasing said wire;
advancing said wire to form a cylindrical section.
~RIEF DESCRIPTION OF THE DRAWINGS
In the drawings like numerals $dentify like components throughout the several views.
FIG. 1 i~ a side view of an integrated circuit die onto which flying gold leads are ball bonded and 6traightened by a ball bonding machine.j FIG. 2 8hows the ~ix step6 that the flying lead ball bonder performs in order to attach a flying lead to an integrated circuit die.
FIG. 3A show6 the bonding pad pattern on a typical integrated circuit.
FIG. 3B ~hows the corresponding plated-through hole pattern on a circuit board which mates the integrated circuit chip onto the circuit board.
-4b-FIG. 4 shows the relative positions of the integrated circuit chip and the circuit board prior to compression of the flying leads into the plated holes.
FIG. 4A is a closeup view of the relative positions of the integrated circuit chip and the circuit board prior to compression of the flying leads into the plated holes.
FIG. S ~hows the relative positions of the integrated circuit chip and the circuit board after the flying leads have been compressed inside the plated holes of the circuit board.
FIG. 5A i8 a closeup view of a ball-bonded flying lead that has been compressed into a plated-throuqh hole on the circuit board.
FIG. 6 is a ~ide view of the compression process ~4c-wherein a plurality of integrated circuit chip~ hav~ng flying leads ~re att~ched to ~ sin~le printed circult board through the application of ~eating force on c~ul plates which sandwich the circuit board/chip combination.
FIG. 7 shows a plated-through hole pattern for a typical board onto which integrated circuit dice are nttached in the preferred embodiment of the present invention.
FIG. 8 ~hows a module ~ssembly having a plurality of circuit b~ards nested together.
FIG. 9 is a side view of the module assembly of Fig. 8 showing the det~ils of the logic ~umpers and power ~umpers for logic and power interconnection between the stacked ~andwich a~sembly of printed circuit boards.
FIG. lOa shows the twisted wire ~umper logic ~umper or connector.
FIG. lOb 6hows the twisted wire ~umper power ~umper or connector.
FIG. lOc depicts a cross section of the wire used to form a twi~ted wire ~umper connector.
FIG. lOd depicts a cross ~ection of a bird cage formed in a twisted wire ~umper connector.
FIG. lOe shows a cross section of a crimp in the wire.
FIG. 11 shows a cross-sectional view of ~ single twisted wire ~umper logic ~umper that has been installed through axially aligned plated-through holes of a st~ck of printed circuit boards of the module assembly of Fig. 9.
The f$gure is 8hown in an exaggerated scale to clarify the operation of the invention.
FIG. 12 iS acros~-section~l view of a single twisted wire ~umper power ~umper that has been installed through the axially aligned plated-through holes of the ~tacked~array of printed circuit boards of the module 1 324~86 as6embly of Fig. 9. The figure i~ ~hown in ~n exaggerated scale to clarify the operation of the ~nvent~on.
FIG. 13 is a 6ide view of mechanical 6chematic which ha6 been greatly exagger~t~d to show a 6ingle S twi6ted wire jumper compensating for the mi6alignment of a ~tack of printed circuit boards.
FIG. 14 6how6 ~ method for in~talling twi~ted w~re ~umper connectors into a stack assembly of four printed circuit boards.
FIG. 15 6how~ the method of manufacturing twi6ted wire ~umper connectors.
FIG. 16a showE an slternate form of a twi~ted wire ~umper.
FIG. 16b 6hows a cross ~ection of the twisted wire jumper shown in FIG. 16a.
FIG. 16c shows a cross section of the twisted wire jumper shown in FIG. 16a.
DETAILED DESCRIPTION OF THE
PREFERRED EMBODINE_ The preferred embodiment of the present invention involves the high-density packing of 6ilicon or gallium srsenide (GaAs) integrated circuit chips onto ~ingle-layer or multi-lsyer interconnect printed circuit bosrds. The circuit boards have plated-through holes or interconnection apertures which permit the hiqh-density packing of circuit bosrds in a sandwiched arrangement. The application of this technology permits improved speed, improved hest dissipation, and improved packing density required for modern ~upercomputers such ~s the Cray-3 manufactured by the as6ignee of the present invention.
' In the preferred embodiment of this application, the integrated c$rcuit chips are att~ched to the circuit board by flying yold leads, ~8 discussed below and disclosed in Canadian application Serial No. 567,0a4 5 which i6 ~s~igned to the 6ame assignee of the present invention. By placing the integrated circuits directly on the circuit, the bulky packaging normally found on inteqrated circuit~ is elimina~ed.
Fl~inq Lead Construction FIG. 1 ~hows the preferred embodiment for attaching the flying gold leads to the 6ilicon or gallium arsenide packaged chip or die before attachinq the die to the circuit board. The leads ar0 made of soft gold wire which is approximately 3 mil6 in diameter. The GaA~ chips u~ed in the preferred embodiment contain 52 bonding pads which have a sputtered soft gold finish. The ob~ective of the die bonding operation is to form a gold-to-gold bond between the wire and the pad. A Hughes automatic thermosonic (gold wire) ball bonding machine Model 2460-II
may be modified to perform this operation. Thi~ machine is available from Hughes ~ool Company, Los Angeles, California. This machine wa8 designQd and normally used to make pad-to-lead frame connections in IC packages and ha~
been modified to perform the step~ of flying lead bonding a~ described below. The modifications include hardware and software changes to allow feeding, flaming off, bonding and breaking heavy gauge gold bonding wire (up to 0.0030 dia.
Au wire).
The Hughe~ automatic b~ll bonding machine ha~ an X-Y positioning bed which is used to posltion the die for bonding. The die is loaded on the bed in a heated ~acuum fixture which holds up to 16 dice. The Hughes bonding machine i~ aquipped with a vi~ion system which can recognize the die patterns without human intervention and position each bonding pad for proce~slng.
The soft gold wire thst i~ used for the flying leads in the preferred embodiment of the pre~ent invention S is sometimes referred to ~s sticky gold or tacky gold.
This gold bonding wire i~ formed from a 99.994 high-purity ~nnealed gold. The process of annealing the h$gh-purity gold results in a high elongation (20-25~ ~tabilized and ~nnealed)~ low tensile strength (3.0 mil., 50 gm. min.) gold wire which is dead ~oft. The wire composition (99.99%
pure Au non-Beryllium doped) i~ ns follows:
Gold 99.990% min.
Beryllium O.002% max.
Copper 0.004% max.
Other Impurities (each) 0.0034 max.
Total All Impurities 0.010% max.
This type of gold i8 available from Hydrostatics (HTX
grade) or equivalent.
Referring to FIG. l, the flying lead die bonding procedure begins with the formation of a soft gold ball 106 at the tip of the gold wire 101. The wire i8 fed from a supply spool (not shown) through a nitrogen-filled tube lO9 (shown in FIG. 2) to a ceramic capillary 100. The inside of the capillary is ~st 61ightly l~rger than the wire di~meter. The direction of nitrogen flow in the connecting tube 109 can be altered to drive the wire either toward the die or toward the supply spool. Thi~ allows the gold wire to be fed into or withdrawn from the capillary t$p.
The gold ball 106 formed at the end of the gold wire 101 i6 thermo60nically bonded to bonding pad 105 of chip 104. The capillary tip 102 of capillary 100 is capable of heat$ng the ball bond to 300C concurrent with pressing the ball 106 onto the pad 105 and ~onically 1 3246~6 vibrating the connection until a etrong electrical snd mechanical connection i8 formed. The cspillary 100 $8 then withdrawn from th0 ~urface of the die 104 and tho wire 101 is extruded from the tip 102. A notching mechanism, added to the Hughes ball bonder to perform the specific notching operation described herein, i5 used to make ~ notch 107 at the appropriste height, thus defining the length of the flying lead. The wire clsmp lOB grasps the gold wire 101 ~nd the capillary i8 withdrawn upward, breaking the flying lead at 107 ~nd concurrently performing a nondestructive test of the ball bond to bonding pad connection and slso straightening and stiffening the flying lead.
The sequence of steps required to make a flying lead bond to the package die i6 6hown in FIG. 2. Step 1 begins with the feeding of a predetermined amount of wire through the capillary 100. A mechan~cal arm then po~itions an electrode 114 below the capillary tip 102 and a high-voltage electrical current forms an arc which melt6 the wire and forms a gold ball with a diameter of approximately 6 mils. This operation is called electrostatic flame-off (EFO). Ball size is controlled through ad~ustment of the EFO power supply output. During this step, the cl~mp8 108 are closed and the nitrogen drag is off. This action occurs above the surface of the integr~ted circuit chip BO ns to avoid any damage to the chip during the EFO ball forming process.
In step 2, the nitrogen drag 109 withdraws the supply wire 101 into the capillary 100 and tightens the ball against the capillary t$p 102.
The capillary tip 102 is heated to approximately 200C to assist in keeping the gold wire 101 in a malleable state. The die fixture is also heated to 200C
to avoid wire cooling during the bonding process. The die fixture i8 made of Teflon*-coated aluminum. Teflon is a trademark for polytetrafluoroethylene. As shown in *Trademark 9 FIG. 1, a vacuum cavity or vacuum plate 103 hold5 the die 104 in position on the fixture during the bondin~ process.
In ~tep 3, ~he bonding mschine lower~ the capillary 100 to the surface 105 of a bonding pad and applies high pre6sure (range of 30-250 gram~) to the trapped gold ball 106 along with ultraqonic vibration at the capillary tip 102. The capillary t$p 102 i3 flat, with a 4-mil inside diameter and an B-mil out~ide diameter. ~he ball 106 i6 flattened to about a 3-mil height and a 6-mil di meter. ~ltra~onic energy is supplied through the ceramic capillary 100 to vibrate the gold ball 106 and scrub the bonding pad surface. The sound i8 oriented 80 that the gold ball 106 moves psrallel to the die ~urface.
The Hughes ball bonding machine has the ability to vary the touch-down velocity, i.e., soft touch-down for bonding GaAs, which i8 program selected. The ultrasonic application is also program selected.
In step 4, the capillary 100 is withdrawn from the surface of the die 104, extending the gold wire 101 as the head is raised. The nitrogen drag is left off and the capillary is raised to a height to allow enough gold wire to form the flying lead, a tail length for the next flying lead, and a ~mall amount of clearance between the tail length and the capillary tip 102. The Hughes ball bonder device is capable of sQlecting the height that the capillary tip can move up to a height of approximately 0.750 inch.
In 6tep 5, ~n automatic notching m~chanism 115 moves into the area of the extended qold wire 101 and strikes both sides of the wire with steel blades. This is e~sentially n scis~or action which cuts most of the way through the gold wire 101, forming a notch 107 (F~G 1). me notch 107 is made 27 mils above the surface of the die The notching mechanism has been added to the Hughes ball bonder for the precise termination of the flying leads. The Hughes ball bonder has been modified to measure and display ~ 32~686 the notch mechanism height. The activation signal for the notch mechanism iB provided by the Hughes ball bonder system for the proper activation during the sequence of ball bonding. The flying lead length i8 ad~ustable from between 0.0 mils to 50.0 mil6. It will be appreciated by those 6killed in the art that the notching function can be accomplished with a variety of ~echani~ms 6uch as the scissor mechanism di6closed above, a hammer-anvil system, and a variety of other mechanisms that merely notch or completeiy sever the wire 101.
In step 6, clamp 108 closes on the gold wire 101 above the capillary 100 and the head i~ withdrawn until the gold wire breaks st the notched point. This 6tretching process ~erves several useful purposes. Primarily, the gold wire is straightened by the stretching force and stands perpendicular to the die 6urface. In addition, the bond is non-destructively pull-tested for adhe~ion at the bonding pad. The lead 101 is terminated at a 27-mil height above the die ~urface 104 in the preferred embodiment. At the end of step 6, the capillary head for the bonding mechanism is positioned over a new bonding pad and the process of steps 1-6 begins again. The bonding wire 101 is partially retracted into the capillary once again, and the clamps are closed, as shown in 6tep 1, 60 that a new ball may be formed by the EF0.
The die positions are roughly determined by the loading po~itions in the vacuum fixture. The Hughes automatic bonding mschine is able to ad~ust the X-Y table for proper bonding position of the individual die. An angular correction i~ automaticnlly made to ad~ust for tolerance in placing the die in the vacuum fixture. This i8 done through a v$sion sy~tem which recognizes the die pad configurations. Using the modified Hughe~ automatic bonding machine with the current bonding technique, a minimum bonding rate of 2 die pads per ~econd is possible.
Circuf t Board Con~truction Once the gold bonding leads are attached to the inte~rated circuit chip or die, the die 18 ready to be ~ttached to the circuit board. As shown in FIG. 3A, the bonding pattern of the integrated circuit die 104 matchec the plated hole pattern on the circuit board 110,~hown in FIG.3B. For example, the top view of integrated circuit die 104 in FIG. 3A shows the bonding pad 105 in the upper right corner. The circuit board 110 shown in FIG. 3B shows a corresponding plated hole 111 which i6 aligned to receive the b~ng lead ~rcm box~ng pad lO5 (shcwn in FIG. 3A) when circuit b~
110 is placed over integr~ted circuit 104 and the flying leads are inserted into the hole pattern on the circuit board. Thus, each bonding pad of integrsted circuit 104 has a corresponding plated hole on circuit board 110 aligned to receive the flying leads.
The circuit board assQmbly operation begins with the insertion of the die into the circuit board. The circuit board is held in a vacuum fixture during the inser-tion process to make sure that the board remains flat.
Insertion can be done by hend under ~ binocular microscope or production assembly can be done with a pick-and-place machine.
Referring to FIG. 4, the circuit board 110 with the loo~ely placed~diQ 104 is mounted on an ~luminum vacuum caul plate (lower c~ul plate) 113. Steel guide pins (not shown) are placed in corner holQs of the circult board to prevent board motion during the assembly operation. A
second (upper) caul plate 112 is then pl~ced on the top ~ide of the circuit board populated with chips to press again~t the tops (non-pad side) of the chips 104. The sandwich assembly comprising the circuit board, the chip and the c~ul plates i8 then placed in a press and pressure i6 applied to buckle and expand the gold le~ds 101 in the plated hole~ 111 of the circuit board.
The 6ide v~ew of the sandwiched circuit board 110, integrated circuit chip 104, ~nd c~ul pl~tes 112 ~nd 113 in FIGS. 4 and 5 illustrates the position of the gold leads 101 before and after the pressing operation, respectively.
In the preferred embodiment there iB a 9-mil exposure of gold lead 101 of a total lead length of 29 mil~ which upon compression will buckle and expand into the plated hole 111 of the circuit board 110. The 3-mil diameter wire 101 in a 5-mil diameter hole 111 means the initial fill i~ 36 percent of the available volume. After pressing, the fill ha6 increased to 57 percent as a result of the 9.2-mil shortening of the gold lead 101. As shown in greater detail in FIGS. 4a and Sa, the lead typically buckles in two or more places, and these corners are driven into the sides of the plated hole 111 of the circuit board. The integrated circuit pad 105 i8 electrically connected to the flying lead by the ball bonding proce~s. The flying wire also electrically connects the integr~ted circuit to the circuit board through the pressing operation.
The circuit board 110 may be removed from the press with the integrated circuit chip 104 securely attached and electrically bonded to the plated holes of the circuit board.
FIG. 6 sh,ows a view of the circuit board press which is used to attach the integrated circuits to the printed circuit board. The upper caul plate 112 iB a Teflon-coated seating c~ul plate which iB aligned through alignment pins 114 with the circuit board 110 and the lower caul plate 113 which is a vacuum caul plate to hold the circu~t board flat during the pressing procQss. The alignment pins 114 are used to prevent the printed circuit board 110 from ~liding or otherwise moving during the pressing process. A seating force is ~pplied to the top of upper caul pl~te 112 which forces the excess flying lead material into the plated holes of printed circuit board 110. Thus, integrated circuits 104 are mechanically and electrically bonded to printed circuit board 110.
It will be ~ppreciated by tho~e ~kill~d ln the art that many variations of the above-described pressing operation can be used which results in the ~me or oquivalent connection of the flying lead~ to the circuit boards. For example, the flying leads of the chips could be completely in~erted into the through-plated holes of the circuit board prior to the pressing operation with the excass gold leads p~otruding out the opposlte ide. The first caul plate could then be used to hold the chip onto the circuit board while the second c~ul plate is used to compress the leads into the holes.
Module AssemblY Construction FIG. 7 shows an ex~mple of a printed circuit board hole pattern for the circuit boards u6ed in the Cray-3 computer manufactured by the assignee of the present invention. In the preferred embodiment of the present invention, each circuit board provides 16 patterns of plated-through hole~ for receiving the flying leads of 16 integrated circuits. The 16 integrated circuits are ~tt~ched to the circuit board ~hown ~n FIG. ? through the pre~sing process previously described. Each aperture pattern on the circuit board 110 corresponds to the contact pad pattern shown on FIG. 3, from which the bonded flying leads extend outward as shown in FIG. 4.
Each corner of circuit board 110 has a group bf four plated-through holes 304 which are used for alignment during initial assembly. These apertures 304 are also used for power distribution in the completed module.
In the preferred embodiment of the present invention, 16 circuit boards 110 of the type shown in FIG. 7 are stacked together to form a module assembly 200 as - 1 3246~6 shown in both FIG. 8 and FIG. 9. The circuit boards 110 ~re arranged in n 4 x 4 matrix on each of four layers, creating an X-Y-Z matrix of 4 x 4 x 4 circuit board~.
Therefore, each module assembly 200 has 64 circuit boards containing 16 integrated circuit chips each, ~iving a total of 1,024 integrated circuit chips per module assembly.
In the preferred embodiment, the module assembly 200 is 4.76 inches wide, 4.22 inches long, ~nd 0.244 inch thick. As is shown in FIG. 8, ~t one edge of the module sssembly are four machined metsl power blade~ 201a-201d.
These power blades are used both for mechanical connection to the cabinet into which the module as6emblies are placed ~nd for electrical connection to the system power ~upplies.
At the opposite side of the module assembly are 8 edge connectors 202a-202h used to communicate with other modules. These connectors form the communication paths to the other module assemblies within the machine. The bundles of wires between the circuit boards of the module s6sembly 200 and the board edge connectors 202a-202h ~re 2U provided with strain relief member~ 240a-240h respectively.
Each strain relief is a plastic member which protrudes from the edge of the circuit boards. The interconnected wires pass through holes in the strain relief members between the circuit boards and the floating connectors 202a-202h. In this fashion, the flexing of the wlres during the connection and disconnection of connectors 202a-202h does not strain the soldered connection of the wires to the circuit boards. The strain relief members 240a-240h also serve a~ spacers between the circuit boards in a fashion s$milar to spacer6 203 described below. I
Electrical communication between the integrated circuit chips of each board 110 is accomplished by means of the prefabricated foil patterns on the surface and buried within each circuit board. The electrical communication between circuit boards 110 in the X-Y plane is by means of twisted wire jumpers 231 and 232 along the Z-axis (perpendicular to the planar surface of the circuit boards and the module assembly) effecting electrical connection between the circuit boards llO, two logic plates 216 and 217 sandwiched in the center of the module assembly 200 and a centrally located power distribution board 210 sandwiched between the logic plates, as shown in FIG. 9.
The z-axis twisted wire ~umper6 231 and 232 may be used for electrical communication signals and for power distribution. The Z-axis ~umpers may be placed in any of the area on circuitboards 110 that is not occupied by an integrated circuit.
In the preferred embodiment of the assembly module, anywhere from 200-1000 z-axis logic ~umper8 231 may be used for a single circuit board stack. 6400-11,000 ~umpers may be used for a module 200.
FIG. 9 shows a sectional view of a module assembly 200. In the preferred embodiment, module assembly 200 is constructed as a sandwich of a electronic assemblies. These assemblies include a plurality of populated circuit boards 212,214,219,221,which are spaced apart from each other using insulated spacers, such as the one illustrated at 203. Another example of electronic assemblies are the logic plates 216 and 217 which are in contact with and are axially aligned with a power plate 210. All of the circuit boards are orientated 80 that the flying leads of the integrated circuits 104 are away from the power plate 2L0. Also as shown in FIG. 9, power blade 201 abuts circuit boards 212, 214, 219, 221 and logic plates 216 and 217. Additionally, power plate 210 extends into power blade 201. FIG. 9 shows all ma~or component6 of a completely assembled module assembly 200 with the exception of the edge connectors which have been omitted for clarity.
All the electronic assemblies including the circuit boards and the logic plates 216 and 217 are designed 80 that when they are assembled into a module, 1 32~686 their plated-through holes become subQt~ntially aligned in the Z-axis, with the complimentary plated-through holes of the other circuit boards and logic plates.
The power plate 210 i~ designQd ~o that when it iR
~ssembled into a module, its larger unplated holes ~ubstantially align in the Z axis with the plated-through holes of the circuit boards and logic plates. Likewise, circuit boards 110 and power plates 210 sre designed so that when assembled in a module a~embly, their plated-through holes 304 become substantially aligned in the Z-axis with corresponding plated-through holes on other circuit boards and power plates.
However, logic plates 216 and 217 are designed so that when they are a~sembled into a module, their plated-through holes are sub~tantially aligned in the Z axi~ withthe plated-through holes 304 of the circuit boards and power plate.
Electrical communication between the integrated circuit chips on each board is accomplished in the X-Y
plane by means of prefabricated foil patterns on the surface of, and buried within, each circuit board.
Electrical communication between circuit boards 21~, 214, 219, 221 is routed via foil patterns buried within logic plate~ 216 and 217. Electrical inter-connect~ between circuit board~ 212, 214, 219, 221 and logic plates 216 and 217 are accomplished by inserted electrically conductive Z-nxis twisted wire ~umper log$c ~umpers 231 contacting logic plate interconnection apertures 303 on the circuit boards and logic plates.
As de~cribed in more detail below, the twisted wire ~umper logic ~umpers or connectors have wire bird-cage, or bulged portions that have a greater outer radius than the inner radius, or inner contact surface, of the complementary interconnection apertures shown as plated-through holes 303. When a twist-pin logic jumper 231 is inserted into the module assembly, the wire bird-cage portions compress against the plated-through holes 303 thereby forming low resistance connections.
Electrical power di~tribution to the integrated circuit chips on each board 110 i~ accomplished by means of prefabricated foil pattern~ on the surface of, and buried within, each circuit board 110. Electrical power is di~tributed to circuit board~ 212, 214, 219, 221 through power plate 210 which connects to each of the power blades 201a-201d. Electrical powex inter-connections between circuit boards 212, 214, 219, 221 and power plate 210 are accomplished by inserted Z-axis twisted wire ~umper power jumpers or connectors 232. As described in more detail below, the twisted wire jumper power jumpers also have bulged portions, or wire bird-cages that, when compressed, have a greater outer radius than the inner radius, or inner contact surface, of the interconnection apertures represented by plated-through holes 304. When a twist-pin power jumper 232 is inserted in the module assembly, the wire bird-cages compress against the plated-through holes 304 thereby forming low impedance connections.
In the preferred embodiment, module assembly 200 i8 stacked with other module assemblies in a fluid cooling tank and po~itioned ~o that the planar surfaces of the module assembly are stacked vertically. Thus, in the preferred embodiment, FIG. 9 i8 a top-down look at module assembly 200. A type of cooling apparatus suitable for cooling the circuit board module assemblies of the present invention i8 described in V. S. Patent No.i4,590,538.
Cooling channels 230, a8 shown in FIG. 9, are provided to allow the cooling fluid to rise through the module assembly to remove the heat produced by the integrated circuits 104. Heat transfer occurs between circuit boards 1 through 4 (levels 212, 214, 219, and 221 respectively) and the cooling fluid in channels 230.
Cooling channels 230 are created by spacing the circuit boards populated with integrated circuit~ 104 from one another and from the logic plates using the above mentioned insulated spacer6 203. The insulated spacers 203 are held in place by twisted wire ~umper power ~umpers 232 during module assembly.
Twist-Pin Connectors FIG. lOa ~hows a single logic twisted wire ~umper connector for coupling logic level signals between the various electronic assemblies. The preferred embodiment of the twisted wire ~umper shown in FI;G. lOa includes a leader section 260, and a cylindrical tail section 261. Six bird cages 300 are formed between the crimps shown on logic jumper 231. It is preferred to weld the ends of the twisted wire jumper to form blunt nose sections as shown by weld 306. The leader 260 and the tail 261 may beyond the module assembly after insertion to assist in both installation of the twisted wire jumper connector and its removal during module disassembly. At each end of the connector a laser weld 306 is used to keep the wires making up the twisted wire jumper connector 231 from unravelling. The crimps 302 are used to form the wire bird cages 300. The crimps 302 and cages 300 are spaced along the twisted wire jumper to match the interboard spacing. It has proved desirable to extend the cages beyond the edges of the plated-through apertures in the printed circuit boards. For the Cray-3 product this has resulted in .028 inch crimp spacing. The 8iX bird cages 300 are made as described below.
Refer to FIG. lOc. The preferred embodiment the logic twisted wire ~umper 231 is m~de from seven strand multi-filament Be/Cu wire tempered to either 1/4 or 1/2 hard. It is preferred to u~e w~re with uniform ~trand diameters of approximately l.S to 1.6 mils in diameter. It ---` 1 324686 iB al80 preferred to use a nickel flashed, 30 microinch gold plated, beryllium copper alloy 25 CDA wire available from California Fine Wire Co.and other vendors. The ~even strands ~re configured ~ a ~ix around one helix. The wire diameter i8 approximately 4.8 mils before the bird cages 300 ~re formed. Refer to FIG. lOd. The bird cages 300 bulge outw~d to an outer radius of approximately 8.0 mils.
Refer to FIG. lOe. In the preferred embodiment, the individual ~trands making up the wire are fused toyether during the crimping operation.
FIG lOb show6 a ~ingle power twisted wire ~umper connector for coupling power to the various electronic assemblies. In the preferred embodiment the power twist- -pin ~umper has a leader section 262, a tail ~ection 263, ~n~ a n~t~r of crimp6 302 fon~ug five wire bind cages 301. The leader 262 and tail 263 may extend beyond the module a66embly to assist in installation and remov~l of the twi~ted wire ~umper connector. At each end of the connector there i6 a weld 307 to keep the wires making up the twisted wire ~umper connector from unraveling.
The 5 bird cages 301 are ~paced 60 that each bird cage substantially aligns with a corresponding power plated-through hole 304 of the module assembly 200.
Refer now to FIG. lOc. In the preferred embodiment the power twisted wire ~umper 232 i8 made from seven 6trands of either 1/4 or 1/2 ~ard, .0048 mil diameter, nickel flashed, 30 microlnch gold plated, beryllium copper alloy 25 CD~
wire. Ihe multi-fil~t wire is wo~d six an~d one (FIG. lOc) in a left handed helix. At pre~ent the preferred wrap i8 30 turn~ per inch. The wire diameter i8 approximately 14.4 mils before the bird cages sre formed~ Refer now to FIG.
lOd. The bird cages bulge outward to an outer radius of approximately 16.0 mils.
~ 20 Refer to FIG. lOe. In the preforred embodiment, the individual ~trand~ making up the wire are fused together during the crimping operation.
FIG. 11 show6 a cut-away view of a single logic 5 twisted wire ~umper in~talled in a module a~embly. The bird cages 300 compress again~t the plated-through holes 303 forming low impedance electrical connections. The leader 260 ~nd tail 261 extend beyond the module a~sembly to assi6t in module disassembly. Also ~hown are conductive paths 400 connected to circuit boards 212, 214, 219, and 221 for logic level routings to integrated circuit6 104.
In addition to the cylindrical leader and tail sections, one or a plurality of cylindrical intermediate sections 305 (Fig. lOa) connect the bird cages to one another at locations along the length of a logic or power jumper. The intermediate sections are of predetermined length sufficient to position the bird cages to align with corresponding plated-through apertures in the electronic as6emblies of the module assembly.
FIG. 12 shows a cut-away view of a 6ingle power twi6ted wire ~umper installed in a module assembly. The bird cages 301 compress against the plated-through holQs 304, forming low impedance electrical connections. The leader 262 nnd tail 263 extend beyond the module assembly to assist in module disassembly. Also shown are conductive paths 401 connected to circuit bo~rd~ 212, 214, 219, and 221 for power routings to in~egrated circuits 104.
-`-` 1 324686 Both ~umpers 231 nnd 232 are flexible and therefore can compensate for minor mi~alignment of a module assembly. FIG.13 shows a single power twisted wire ~umper in~talled in a misaligned module assembly which i~ depicted in greatly exaggerated form to clearly disclose this feature of the invention. The twisted wire ~umper flexes ~o that the bird-cages 301 compress against the plated-through holes 304 of the circuit boards 212, 214, 219, snd 221 and power plate 210. The logic twist-pin ~umper will similarly flex to compensate for module misalignment along any axis.
FIG.14 shows a method of in~erting the twisted wire ~umper connectors. A number of the electronic assemblies are stacked and aligned through the use of guide pins. The leader 262 of twisted wire ~umper 232 is inserted into the interconnection apertures 304 and passed completely through the stacked array. The leader is then grasped and drawn -2la--- 1 3246~6 through the stacked electronic assemblies until it i6 substantially completely through the assemblies. At this point each of the cages is drawn into engagement with the periphery of the various plated-through apertures. The leader is then cut off by a suitable cutter 800. A short stub 802 is left as an aid to the subsequent removal of the twisted wire jumper.
Fig. 15 shows a method of manufacturing the twisted wire jumpers in a preferred embodiment. In step 1, the wire is clamped between two feeder clamps 804 and 806. This operation places the wire under slight tension. Next a laser or other cut off device 808 is used to cut the wire by melting the wire. This operation forms a tip 810 on the wire which is an aid in threading the wire through the circuit board apertures. Next the wire is advanced to form the leader portion of the twisted wire jumper.
The formation of the bird cage structure 812 begins with the crimping operation shown in step 2. The purpose of the crimping operation is to join or fuse the strands of the multi-filament sheath together. This operation also results in the coupling of the outer sheath to the inner core wire as well. If the collar formed by the crimping operation rigidly joins the sheath to the core, the untwisting operation may result in a bird cage which has seven strands in the barrel shaped cage. This converts the wire from a six around one configuration to a seven around zero configuration. The six around one configuration is shown in Fig. 10c, which illustrates a cross section of the wire. The anti-helical twisting operation may displace the core from its center position, and force it into the cage structure.
In this instance the outer periphery of the cage is oomposed of seven strands, not six. The crimp portion 302 of a wire can be seen in Fig. 10e.
Typically two crimped collars are formed at a time. One of the crimping chucks is stationary and the other crimping chuck is rotatable. In step 3 the ., .
., .. . -. - ~, .
rotatable chuck is used to unwind the helical ~heath by rotating the collar in the anti-helical direction while the stationary crimping chuck keeps the wire from turning.
A~ present the preferred degree of rotation is 160 while rotations in the range of 100 to 180 appear to be ncceptable. This counter rotation increases the diameter of the twist wire connector ~nd farms a resilisnt bird cage structure 812 for frictional engagement with apertures of the electronic ~s~emblies, thu~ forming A connector portion.
In step~ 4 and S, once a bird cage i~ formed, the wire is advanced to the next position and the crimping operation i8 resumed to form the next bird cage.
After 811 of the bird cages are formed, the wire i~
advanced to the position shown in ~tep S. Laser 808 shears the tail and leaves a weld to keep the wires from unraveling. Additionally, the blunt end 810 of the next wire ~umper $8 formed. These operations are repeated to form the next twisted wire ~umper.
It is also contemplated to form the bird cages with the center core strand relatively free to absorb tension $orces resulting from the in~ertion of the twist wire ~umpers.
This structural relationship i~ achieved through the use of a laser weld which joins the o~r sheath stR~s 902 to each o~ A.
shown at 906, but rc~ to the center ccre stn~d 905 (FIGS. 16b and 16c).
mis form of co~uctian is shown in FIGS. 16a, 16b and 16c. In FIG.
16a laser weld6 9~0 are formed on the wire 903 through an operation performed by a laser such as that depicted as 808 ln FIG. 15. These laser welds are used to separate the bird cages 904 fro~ each other. In this embodiment the weld6 have a length of 3 to 6 mils while the bird cages themselves are about 28 mils long.
Refer to FIG 16b. The wire 903 i6 formed from six ~6) indiv$dual strands 902 of wire wrapped around a center conductor 905. Referring now to FIG. 16c, the laser weld 900 fuses the BiX outer ~trand~ 902 together, but not to ~he center conductor 905. The welded ~trands form a connection 905. The center conductor 905 c~n ~lide through the connection 906 under ten~ion.
It ~hould be appreci~ted that the crlmping fixtures show in thQ FIG. lS can al~o be adspted to fu~e the helical hheath str~nds to each other.
Those of ordinary skill in the srt will recognize that other types of wire may be u~ed in place of the wire described herein. For example, multi-~tranded wires which ~0 are made with differing strand alloys may be ~ubstituted.
While the present invention has described csnnection with the preferred embodiment thereof, it will be understood that many modifications will be readily ~pparent to those of ordinary skill in the art, and this application $~ intended to cover any ~daption or variations thereof. Therefore, it is manife6tly int~nded that thi6 invention be limited only by the cl~ims and the equivalents thereof.
Claims
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A twisted wire jumper for interconnecting electronic assemblies comprising:
a plurality of cylindrical portions, each comprising;
a central core strand;
a helically wound, multiple strand coil sheath surrounding said central core strand; and a plurality of connector portions, each comprising;
a plurality of resilient strands forming a barrel shaped cage for connection with said electronic assemblies.
2. The twisted wire jumper of claim 1 wherein said coil strands and said core strand have the same strand diameter.
3. The twisted wire jumper of claim 1 wherein said coil strand diameter exceeds the core strand diameter.
4. The twisted wire jumper of claim 1 wherein said coil strand diameter is less than the core strand diameter.
5. The twisted wire jumper of claim 1 wherein said multi-filament coil comprises 6 helically wound strands around a single core strand.
6. A twisted wire jumper for interconnecting electronic assemblies having interconnection apertures comprising:
a central core strand;
multi-filament coil strands surrounding said core strand, forming a plurality of bulged cages for resilient frictional engagement of said interconnection apertures,providing electrical interconnection and releasable mechanical connection between said assemblies.
7. A twisted wire jumper for interconnecting electronic assemblies, which have interconnection apertures, comprising:
a central core strand having a head portion and having a tail portion;
a helically oriented coil surrounding said core strand, wound to form a sequence of bulged cages for resilient frictional engagement of said interconnection apertures, providing electrical interconnection and releasable mechanical connection between said assemblies,and wound to form a sequence of cylindrical sections for the electrical coupling of said bulged cages and for the mechanical support of said bulged cages.
8. The twisted wire jumper of claim 7 wherein said bulged sections are separated from said cylindrical section by crimping said coil to said central core.
9. The twisted wire jumper of claim 7 wherein said bulged sections are separated from said cylindrical section by laser welding said coil to said central core.
10. The twisted wire jumper of claim 7 further including a head section having a blunt nose.
11. The twisted wire jumper of claim 7 further including a tail section having a blunt nose.
12. The twisted wire jumper of claim 10 or 11 wherein said tail section is formed by crimping said helical coil to said center core.
13. The twisted wire jumper of claim 10 or 11 wherein said tail section is formed by laser welding said coil to said central core.
14. A method of manufacturing a twisted wire jumper contact comprising the steps of:
clamping a wire to place it under tension;
melting said wire to form a blunt nose;
crimping said wire at first and second locations to form a pair of crimp collars;
rotating said wire in an anti-helical direction to form a bulged cage section between said collars;
releasing said wire;
advancing said wire to form a cylindrical section.
15. A twisted wire jumper for interconnecting electronic assemblies comprising:
a plurality of cylindrical portions, each comprising;
an elongated central core strand;
a helically wound, multiple strand coil sheath surrounding said central core; and a plurality of cage connector portions, each comprising;
a plurality of resilient strands formed by untwisting selected segments of said sheath to dislocate said center core.
16. An elongated jumper for interconnecting a plurality of electronic assemblies, comprising a plurality of cylindrical portions and a plurality of connector portions separated by a cylindrical portion along the length of the jumper, wherein:
each of the plurality of cylindrical portions comprises:
a central core strand;
a helically wound, multiple strand coil sheath surrounding said central core strand; and each of the plurality of connector portions comprises:
a plurality of resilient strands forming a barrel shaped cage extending transversely outward a greater distance than the sheath of an adjacent cylindrical portion, the barrel shaped cage adapted for connection with said electronic assemblies.
17. The jumper of claim 16 wherein said coil strands and said core strand have the same strand diameter.
18. The jumper of claim 16 wherein said coil strand diameter exceeds the core strand diameter.
19. The jumper of claim 16 wherein said coil strand diameter is less than the core strand diameter.
20. The jumper of claim 16 wherein said multiple strand coil sheath comprises six strands helically wound around the central core strand.
21. A jumper for interconnecting a plurality of electronic assemblies, each electronic assembly having at least one interconnection aperture, said jumper comprising:
a central core strand: and a plurality of multifilament coil strands surrounding said core and wherein:
at each of a plurality of first locations the coil strands are in contact with the core strand; and at each of a plurality of second locations spaced between two adjacent first locations, the coil strands extend outward away from the core strand to form a bulged cage for resilient frictional engagement with said interconnection apertures to provide an electrical interconnection and a releasable mechanical connection between said assemblies.
22. A jumper for interconnecting a plurality of electronic assemblies, each electronic assembly having at least one interconnection aperture, said jumper comprising:
a central core strand having a head portion and having a tail portion;
a helically oriented coil surrounding said core strand, the helically oriented coil wound to form a sequence of bulged cages for resilient frictional engagement of said interconnection apertures, the bulged cages providing an electrical interconnection and a releasable mechanical connection between said assemblies, and the helically oriented coil also wound to form a sequence of cylindrical sections for the electrical coupling of said bulged cages and for the mechanical support of said bulged cages.
23. The jumper of claim 22 wherein at least one of said bulged cages is separated from a cylindrical section by crimping said coil to said central core.
24. The jumper of claim 22 wherein at least one of said bulged cages is separated from a cylindrical section by laser welding said coil to said central core.
25. The jumper of claim 22 further including a leader cylindrical section having a blunt nose at a first end of the jumper.
26. The jumper of claim 22 further including a tail cylindrical section having a blunt nose at a second end of the jumper.
27. A method of manufacturing an elongated twisted wire jumper from a wire formed by a plurality of helically wound strands, comprising the steps of:
clamping said wire to place it under tension;
melting said wire to form a blunt nose;
crimping said wire at first and second locations to form a pair of crimp collars;
rotating said wire in an antihelical direction to form a bulged cage section between said collars;
releasing said wire;
advancing said wire to form a cylindrical section.
28. A twisted wire jumper for interconnecting electronic assemblies comprising:
an elongated central core strand;
a helically wound, multiple strand coil sheath exteriorly surrounding said central core;
a plurality of cylindrical portions, each comprising:
a segment of the elongated central core strand;
a segment of the helically wound, multiple strand coil sheath surrounding said segment of the central core; and a plurality of cage connector portions located at different positions along the jumper from the cylindrical portions, each cage connector portion comprising:
a plurality of resilient strands formed by untwisting selected segments of said sheath between two cylindrical portions to dislocate said central core strand from a central position to an exterior position in the cage connector portion.
29. The jumper of claim 25 wherein said leader cyndrical section is formed by crimping said coil to said central core.
30. The jumper of claim 25 wherein said leader cylindrical section is formed by laser welding said coil to said central core.
31. The jumper of claim 25 further including a tail cylindrical section having a blunt nose at a second end of the jumper.
32. The jumper of claim 26 wherein said tail cylindrical section is formed by crimping said coil to said central core.
33. The jumper of claim 26 wherein said tail cylindrical section is formed by laser welding said coil to said central core.
34. A method of manufacturing an elongated twisted wire jumper from a segment of an elongated wire having a plurality of exterior helically wound strands, comprising the steps of:
forming a blunt nose at a first predetermined location on the segment by fusing the strands integrally together at the first predetermined location;
gripping the segment at a second and a third predetermined spaced apart locations;
rotating said wire at one of the second or third locations in an antihelical direction with respect to the other one of the second or third locations to expand the strands between the second and third locations and form a bulged cage section between the second and third locations.
35. A method as defined in claim 34 wherein the step of forming the blunt nose further comprises fusing the strands together by melting the strands at the first predetermined location.
36. A method as defined in claim 35 wherein the step of fusing the strands together is performed by laser welding the wire at the first predetermined location.
37. A method as defined in claim 34 further comprising:
cutting the segment simultaneously with the step of forming the blunt nose.
38. A method as defined in claim 34 wherein the step of gripping the segment further comprises crimping the strands together at each one of the second and third locations.
39. A method as defined in claim 34 wherein the step of gripping the segment further comprises laser welding the strands together at each one of the second and third locations.
40. A method as defined in claim 39 wherein the wire has a core strand around which the helically wound exterior strands are wound and wherein the step of gripping the segment does not join the exterior strands to the core strand.
41. A method as defined in claim 34 wherein the step of rotating the wire further comprises rotating one of the second or third locations between approximately 100 degrees and approximately 180 degrees with respect to the other one of the second or third locations.
42. A method as defined in claim 41 wherein one of the second or third locations is rotated approximately 160 degrees with respect to the other one of the second or third locations.
43. A method as defined in claim 34, further comprising:
gripping the segment at a fourth predetermined location which is relatively closer to the third location than to the second location: and rotating said wire at one of the third or fourth locations in an antihelical direction with respect to the other one of the third or fourth locations to expand the strands between the third and fourth locations and form a bulged cage section between the third and fourth locations.
44. A method as defined in claim 34 further comprising:
forming at least one cylindrical section from a portion of the segment that has not been formed into a bulged cage section.
45. A method as defined in claim 44 further comprising:
forming one blunt nose at a first end of the segment;
sequentially selectively forming one of a bulged cage section or a cylindrical section along the segment after the step of forming the one blunt nose at the first end; and forming another blunt nose at a second end of the segment after the step of sequentially selectively forming one of a bulged cage section or a cylindrical section.
46. A method as defined in claim 45 further comprising:
moving the segment linearly along an axis of the segment during the steps of forming the blunt noses and each bulged cage section and each cylindrical section.
47. A method as defined in claim 34 wherein the second and third locations are each spaced from the first location.
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A twisted wire jumper for interconnecting electronic assemblies comprising:
a plurality of cylindrical portions, each comprising;
a central core strand;
a helically wound, multiple strand coil sheath surrounding said central core strand; and a plurality of connector portions, each comprising;
a plurality of resilient strands forming a barrel shaped cage for connection with said electronic assemblies.
2. The twisted wire jumper of claim 1 wherein said coil strands and said core strand have the same strand diameter.
3. The twisted wire jumper of claim 1 wherein said coil strand diameter exceeds the core strand diameter.
4. The twisted wire jumper of claim 1 wherein said coil strand diameter is less than the core strand diameter.
5. The twisted wire jumper of claim 1 wherein said multi-filament coil comprises 6 helically wound strands around a single core strand.
6. A twisted wire jumper for interconnecting electronic assemblies having interconnection apertures comprising:
a central core strand;
multi-filament coil strands surrounding said core strand, forming a plurality of bulged cages for resilient frictional engagement of said interconnection apertures,providing electrical interconnection and releasable mechanical connection between said assemblies.
7. A twisted wire jumper for interconnecting electronic assemblies, which have interconnection apertures, comprising:
a central core strand having a head portion and having a tail portion;
a helically oriented coil surrounding said core strand, wound to form a sequence of bulged cages for resilient frictional engagement of said interconnection apertures, providing electrical interconnection and releasable mechanical connection between said assemblies,and wound to form a sequence of cylindrical sections for the electrical coupling of said bulged cages and for the mechanical support of said bulged cages.
8. The twisted wire jumper of claim 7 wherein said bulged sections are separated from said cylindrical section by crimping said coil to said central core.
9. The twisted wire jumper of claim 7 wherein said bulged sections are separated from said cylindrical section by laser welding said coil to said central core.
10. The twisted wire jumper of claim 7 further including a head section having a blunt nose.
11. The twisted wire jumper of claim 7 further including a tail section having a blunt nose.
12. The twisted wire jumper of claim 10 or 11 wherein said tail section is formed by crimping said helical coil to said center core.
13. The twisted wire jumper of claim 10 or 11 wherein said tail section is formed by laser welding said coil to said central core.
14. A method of manufacturing a twisted wire jumper contact comprising the steps of:
clamping a wire to place it under tension;
melting said wire to form a blunt nose;
crimping said wire at first and second locations to form a pair of crimp collars;
rotating said wire in an anti-helical direction to form a bulged cage section between said collars;
releasing said wire;
advancing said wire to form a cylindrical section.
15. A twisted wire jumper for interconnecting electronic assemblies comprising:
a plurality of cylindrical portions, each comprising;
an elongated central core strand;
a helically wound, multiple strand coil sheath surrounding said central core; and a plurality of cage connector portions, each comprising;
a plurality of resilient strands formed by untwisting selected segments of said sheath to dislocate said center core.
16. An elongated jumper for interconnecting a plurality of electronic assemblies, comprising a plurality of cylindrical portions and a plurality of connector portions separated by a cylindrical portion along the length of the jumper, wherein:
each of the plurality of cylindrical portions comprises:
a central core strand;
a helically wound, multiple strand coil sheath surrounding said central core strand; and each of the plurality of connector portions comprises:
a plurality of resilient strands forming a barrel shaped cage extending transversely outward a greater distance than the sheath of an adjacent cylindrical portion, the barrel shaped cage adapted for connection with said electronic assemblies.
17. The jumper of claim 16 wherein said coil strands and said core strand have the same strand diameter.
18. The jumper of claim 16 wherein said coil strand diameter exceeds the core strand diameter.
19. The jumper of claim 16 wherein said coil strand diameter is less than the core strand diameter.
20. The jumper of claim 16 wherein said multiple strand coil sheath comprises six strands helically wound around the central core strand.
21. A jumper for interconnecting a plurality of electronic assemblies, each electronic assembly having at least one interconnection aperture, said jumper comprising:
a central core strand: and a plurality of multifilament coil strands surrounding said core and wherein:
at each of a plurality of first locations the coil strands are in contact with the core strand; and at each of a plurality of second locations spaced between two adjacent first locations, the coil strands extend outward away from the core strand to form a bulged cage for resilient frictional engagement with said interconnection apertures to provide an electrical interconnection and a releasable mechanical connection between said assemblies.
22. A jumper for interconnecting a plurality of electronic assemblies, each electronic assembly having at least one interconnection aperture, said jumper comprising:
a central core strand having a head portion and having a tail portion;
a helically oriented coil surrounding said core strand, the helically oriented coil wound to form a sequence of bulged cages for resilient frictional engagement of said interconnection apertures, the bulged cages providing an electrical interconnection and a releasable mechanical connection between said assemblies, and the helically oriented coil also wound to form a sequence of cylindrical sections for the electrical coupling of said bulged cages and for the mechanical support of said bulged cages.
23. The jumper of claim 22 wherein at least one of said bulged cages is separated from a cylindrical section by crimping said coil to said central core.
24. The jumper of claim 22 wherein at least one of said bulged cages is separated from a cylindrical section by laser welding said coil to said central core.
25. The jumper of claim 22 further including a leader cylindrical section having a blunt nose at a first end of the jumper.
26. The jumper of claim 22 further including a tail cylindrical section having a blunt nose at a second end of the jumper.
27. A method of manufacturing an elongated twisted wire jumper from a wire formed by a plurality of helically wound strands, comprising the steps of:
clamping said wire to place it under tension;
melting said wire to form a blunt nose;
crimping said wire at first and second locations to form a pair of crimp collars;
rotating said wire in an antihelical direction to form a bulged cage section between said collars;
releasing said wire;
advancing said wire to form a cylindrical section.
28. A twisted wire jumper for interconnecting electronic assemblies comprising:
an elongated central core strand;
a helically wound, multiple strand coil sheath exteriorly surrounding said central core;
a plurality of cylindrical portions, each comprising:
a segment of the elongated central core strand;
a segment of the helically wound, multiple strand coil sheath surrounding said segment of the central core; and a plurality of cage connector portions located at different positions along the jumper from the cylindrical portions, each cage connector portion comprising:
a plurality of resilient strands formed by untwisting selected segments of said sheath between two cylindrical portions to dislocate said central core strand from a central position to an exterior position in the cage connector portion.
29. The jumper of claim 25 wherein said leader cyndrical section is formed by crimping said coil to said central core.
30. The jumper of claim 25 wherein said leader cylindrical section is formed by laser welding said coil to said central core.
31. The jumper of claim 25 further including a tail cylindrical section having a blunt nose at a second end of the jumper.
32. The jumper of claim 26 wherein said tail cylindrical section is formed by crimping said coil to said central core.
33. The jumper of claim 26 wherein said tail cylindrical section is formed by laser welding said coil to said central core.
34. A method of manufacturing an elongated twisted wire jumper from a segment of an elongated wire having a plurality of exterior helically wound strands, comprising the steps of:
forming a blunt nose at a first predetermined location on the segment by fusing the strands integrally together at the first predetermined location;
gripping the segment at a second and a third predetermined spaced apart locations;
rotating said wire at one of the second or third locations in an antihelical direction with respect to the other one of the second or third locations to expand the strands between the second and third locations and form a bulged cage section between the second and third locations.
35. A method as defined in claim 34 wherein the step of forming the blunt nose further comprises fusing the strands together by melting the strands at the first predetermined location.
36. A method as defined in claim 35 wherein the step of fusing the strands together is performed by laser welding the wire at the first predetermined location.
37. A method as defined in claim 34 further comprising:
cutting the segment simultaneously with the step of forming the blunt nose.
38. A method as defined in claim 34 wherein the step of gripping the segment further comprises crimping the strands together at each one of the second and third locations.
39. A method as defined in claim 34 wherein the step of gripping the segment further comprises laser welding the strands together at each one of the second and third locations.
40. A method as defined in claim 39 wherein the wire has a core strand around which the helically wound exterior strands are wound and wherein the step of gripping the segment does not join the exterior strands to the core strand.
41. A method as defined in claim 34 wherein the step of rotating the wire further comprises rotating one of the second or third locations between approximately 100 degrees and approximately 180 degrees with respect to the other one of the second or third locations.
42. A method as defined in claim 41 wherein one of the second or third locations is rotated approximately 160 degrees with respect to the other one of the second or third locations.
43. A method as defined in claim 34, further comprising:
gripping the segment at a fourth predetermined location which is relatively closer to the third location than to the second location: and rotating said wire at one of the third or fourth locations in an antihelical direction with respect to the other one of the third or fourth locations to expand the strands between the third and fourth locations and form a bulged cage section between the third and fourth locations.
44. A method as defined in claim 34 further comprising:
forming at least one cylindrical section from a portion of the segment that has not been formed into a bulged cage section.
45. A method as defined in claim 44 further comprising:
forming one blunt nose at a first end of the segment;
sequentially selectively forming one of a bulged cage section or a cylindrical section along the segment after the step of forming the one blunt nose at the first end; and forming another blunt nose at a second end of the segment after the step of sequentially selectively forming one of a bulged cage section or a cylindrical section.
46. A method as defined in claim 45 further comprising:
moving the segment linearly along an axis of the segment during the steps of forming the blunt noses and each bulged cage section and each cylindrical section.
47. A method as defined in claim 34 wherein the second and third locations are each spaced from the first location.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000616409A CA1324686C (en) | 1989-05-04 | 1992-06-19 | Twisted wire jumper electrical interconnector |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/347,507 US5014419A (en) | 1987-05-21 | 1989-05-04 | Twisted wire jumper electrical interconnector and method of making |
| US347,507 | 1989-05-04 | ||
| CA000615248A CA1304168C (en) | 1989-05-04 | 1989-09-29 | Twisted wire jumper electrical interconnector |
| CA000616409A CA1324686C (en) | 1989-05-04 | 1992-06-19 | Twisted wire jumper electrical interconnector |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000615248A Division CA1304168C (en) | 1989-05-04 | 1989-09-29 | Twisted wire jumper electrical interconnector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1324686C true CA1324686C (en) | 1993-11-23 |
Family
ID=25673203
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000616409A Expired - Lifetime CA1324686C (en) | 1989-05-04 | 1992-06-19 | Twisted wire jumper electrical interconnector |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1324686C (en) |
-
1992
- 1992-06-19 CA CA000616409A patent/CA1324686C/en not_active Expired - Lifetime
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