GB2362035A - Forming pin contacts to electronic devices - Google Patents

Forming pin contacts to electronic devices Download PDF

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Publication number
GB2362035A
GB2362035A GB0028595A GB0028595A GB2362035A GB 2362035 A GB2362035 A GB 2362035A GB 0028595 A GB0028595 A GB 0028595A GB 0028595 A GB0028595 A GB 0028595A GB 2362035 A GB2362035 A GB 2362035A
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United Kingdom
Prior art keywords
ball
diameter
pin
carrier
bonding
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB0028595A
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GB2362035B (en
GB0028595D0 (en
Inventor
Elwyn Paul Michael Wakefield
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pixelfusion Ltd
ClearSpeed Technology Ltd
Original Assignee
Pixelfusion Ltd
ClearSpeed Technology Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pixelfusion Ltd, ClearSpeed Technology Ltd filed Critical Pixelfusion Ltd
Publication of GB0028595D0 publication Critical patent/GB0028595D0/en
Priority to GB0108418A priority Critical patent/GB2362036A/en
Priority to PCT/GB2001/001737 priority patent/WO2001082362A2/en
Priority to EP01921615A priority patent/EP1275143B1/en
Priority to AU2001248586A priority patent/AU2001248586A1/en
Priority to AT01921615T priority patent/ATE371265T1/en
Priority to DE60130111T priority patent/DE60130111D1/en
Priority to US10/257,842 priority patent/US7137547B2/en
Publication of GB2362035A publication Critical patent/GB2362035A/en
Application granted granted Critical
Publication of GB2362035B publication Critical patent/GB2362035B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/74—Apparatus for manufacturing arrangements for connecting or disconnecting semiconductor or solid-state bodies
    • H01L24/78—Apparatus for connecting with wire connectors
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
    • H01L21/4814—Conductive parts
    • H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
    • H01L21/4853—Connection or disconnection of other leads to or from a metallisation, e.g. pins, wires, bumps
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    • H01L24/10—Bump connectors ; Manufacturing methods related thereto
    • H01L24/11—Manufacturing methods
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/4007—Surface contacts, e.g. bumps
    • H05K3/4015—Surface contacts, e.g. bumps using auxiliary conductive elements, e.g. pieces of metal foil, metallic spheres
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    • H01L2224/85045—Reshaping, e.g. forming the ball or the wedge of the wire connector by heating means, e.g. "free-air-ball" using a corona discharge, e.g. electronic flame off [EFO]
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  • Engineering & Computer Science (AREA)
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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Wire Bonding (AREA)

Abstract

A ball is formed at the end of a wire 10 extending through the bore of a wirebonding tool 12, the ball is brought into contact with the contact surface 16, the ball is then extruded into the bore during thermocompression bonding to form a pin 11. The wire is subsequently disconnected from the pin.

Description

FORMING ELECTRiCAUMECHANICAL CONNECTIONS
FIELD OF THE INVENTION 5
The present invention relates to forming electricallmechanical connections. In particular, the present invention relates to an improved method for forming high-density connections associated with electronic carriers such as integrated circuits (IC'S), semiconductor wafers, ceramic interposers/substrates and printed circuit boards.
BACKGROUND OF THE INVENTION
There are currently several known methods for forming electricallmechanical connections between integrated circuits (IC's) and electronic carriers.
One common method of forming such connections involves bonding suitable conductive wires between bond pads formed on the IC, and respective pads carried by the associated carrier. The wires are bonded using well known thermosonic techniques that utilise ultrasonic and thermal energy to form the required bonds.
A second known method of such connection is known in the art as "bumped die" or "flip chip" bonding. This second method involves the formation of contacts, typically in the form of balls, studs or hemispherical bumps, on the bond pads of the IC. The IC can then be connected to the carrier by bonding the contacts of the IC to a bonding surface of the carrier. The bonding can be carried out 25 using a thermal; thermosonic; andlor adhesive bonding technique.
A third known method of such connection is known in the art as "tape automated bonding" or "TAB bondinj. TAB bonding involves the bonding of a carriers conductive trace directly onto the bond pads of the IC.
Each of the above three connection methods exhibit disadvantages, especially when applied to components having high pin counts andlor where there is a need for chip scale packages (CSP's). For example, thermosonic wire bonding and TAB bonding methods have a disadvantage in that the bond pads must be placed about the periphery of the IC. Another disadvantage of these methods is that the connections from the IC to the carrier are relatively long, and as such, present many well known and understood problems associated with the with routing of signals, especially high frequency signals. Furthermore, another disadvantage associated with thermosonic wire bonding and TAB bonding techniques is that as the physical size of an IC gets smaller, the IC becomes bond pad limited. Bond pad limitation occurs when the size of the]C is determined by the number of connections that need to be made between the]C and the carrier, and not by the functionality of the IC. This is still the case even when dual rows of the finest available pitch (typically less than 100 microns) of bond pads are used. For a given yield of devices per wafer, the physical size of the IC directly affects the absolute number of "good devices" per wafer, and so being limited to a minimum size by bond pad considerations has serious cost implications and such a situation is therefore undesirable and disadvantageous.
One disadvantage associated with flip chip technology is that it does not permit the use of the same fine pitch bond pads that are currently available for thermosonic wire bonding or TAB bonding connection techniques. Typical pitch values for current flip chip technology are greater than 200 microns. However, flip chip technology does have an advantage over thermosonic wire bonding and TAB bonding techniques in that the positioning of the bond pads is not limited. Using flip chip technology, bond pads can be placed, for example, in an area array all over the top surface of an IC. A disadvantage associated with flip chip technology is that the balls, studs or hemispherical bumps, that are employed are limited in height because of the fine pitch requirements i.e. the aspect ratio (AR) of a contact's height (h) to its diameter (md) is typically less than one (AR h:md:S 1). The problem of having contacts with such low value aspect ratios is that the resulting connections of the IC to the carrier tend to transmit mechanical stresses caused by the different coefficients of thermal expansion (CTE) of the IC and carrier materials between the IC and its carrier. One solution to the problem associated with the different WE's of IC and carrier materials is to ensure that the difference between the CTE of the IC and the carrier are within acceptable limits for the size of the IC and its operating temperature range. However, matching such IC and carrier CTE's has an associated disadvantage in that the matching can involve the use of expensive specialist carrier materials. It should be noted that as the semiconductor industry moves towards greater system integration, i.e. systerri-on-chip, the inherently larger]C's compound the present problems of CTE matching. These larger [C's result in greater mechanical stresses, which results in more attention having to be paid to solving the matching problems associated with the different coefficients of thermal expansion (CTE) of the IC and carrier.
In light of the foregoing problems associated with the state of the art, it is desirable to provide an improved method of forming electricallmechanical connections between a plurality of electronic carriers. It is also desirable to provide an improved method of forming high stress tolerant electricallmechanical connections which are suitable for use with a variety of electronic carriers.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a method of forming a connection on a surface of an electronic carrier, the method comprising: providing a malleable wire having a first diameter via a capillary tool having a bore of a second diameter, the second diameter being greater than the first diameter; forming a ball of material on an end of the wire; bonding the ball of material to a bonding surface of an electronic carrier to form a connection having a third diameter; extruding the ball of material into the bore of the capillary tool to form a pin structure having a diameter substantially equal to the second diameter; and disconnecting the wire from the pin structure.
According to the present invention, when the ball has been thermosonically scrubbed against the bond surface such that it makes the necessary, operative, electricallmechanical connection to the bond surface, the bonding apparatus and capillary tool are operatively controlled such that the remaining portion of the ball that is not bonded to the bond surface is allowed to extrude inside the bore of the capillary tool. By operatively controlling the actions of the bonding apparatus and capillary tool beyond the normal limits used for forming ball bonds, an operative pin, or pin- like, connection can be formed within the bore of the capillary. The pin can then be detached from the wire using known techniques.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1 to 4 illustrate one known method of forming and attaching connections to a surface; Figure 5 illustrates in more detail part of a tool used in the method of Figures 1 to 4 diagram of a capillary tool that has a ball that is at the point at which it adheres to a bond surface;.
Figures 6 and 7 illustrate respective power profiles used in methods embodying respective aspects of the present invention; Figure 8 illustrates the formation of a first pin connection, in accordance with a method embodying one aspect of the present invention; Figure 9 illustrates the first pin connection of Figure 8; Figure 10 illustrates the formation of a second pin connection, in accordance with a method embodying one aspect of the present invention; Figure 11 illustrates the second pin connection; Figure 12 illustrates attachment of an IC to a carrier; and Figure 13 illustrates attachment of an]C to a second carrier.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
It should be noted that the accompanying drawings are not to relative, or absolute, scale and are intended as non-limiting examples.
Figures 1 to 4 of the accompanying drawings illustrate a method of forming and attaching a normal ball bond to a surface, such as a surface of an integrated circuit.
Referring to Figure 1, the procedure to form a required connection on a bonding surface 16 begins with feeding, from a supply spoof (not illustrated), a predetermined amount of wire 10 through a bore 11 of a capillary tool 12 of a bonding apparatus (not illustrated). The tip T of the wire 10 extends beyond the end of a capillary tool 12 by a predetermined amount. The wire is held by clamps 14 of the bonding apparatus.
As shown in Figure 2, a ball 18 of material is formed at the tip T of the wire 10. Typically, a mechanical arm positions an electrode 20 adjacent to the tip of the wire 10. A high voltage is applied to the electrode 20 such that an arc is produced between the wire 10 and the electrode 20 and a highvoltage electrical current between the electrode 20 and the tip of the wire 10. The tip of the wire 10 is thereby melted and a ball of material is formed. This ball forming procedure is known as electronic flame-off (EFO).
As shown in Figure 3, lowering the capillary tool causes the wire to be withdrawn so as to locate the ball 18 near the tip of the capillary tool 12.
The ball 18 is then bonded to the bonding surface 16, as illustrated in Figure 4. During this bonding process, the bonding apparatus lowers the capillary tool 12 towards the bond surface 16, thereby holding the ball 18 against the bonding surface. A vertical load L is applied to the capillary tool 12 so that the ball 18 is pressed against the surface 16. The bonding apparatus operates to vibrate the capillary tool 12 at high frequency such that ultrasonic energy is driven through the capillary tool 12. 20 The vibration of the capillary tool 12 serves to vibrate the ball 18 and so "scrub" the ball onto the bonding surface 16. This "scrubbing" action causes the material of the ball 18 to alloy with the material of the bonding surface 16 such that an electricallmechanical connection is formed. The bonding surface can be heated during the ultrasonic scrubbing process in order to aid the 25 formation of the bond. The ultrasonic vibrations applied to the ball 18 cause the material to become more plastic in nature. The plastic nature of the material means that, since it is under a load L, the ball deforms to produce a bonding area. Although not illustrated, after the ball 18 has been bonded to the bond surface 16, the wire 10 is 30 detached from the bonded ball 18. The detachment of the wire 10 from the bonded ball 18 can be achieved using a number of different known techniques. One such technique involves withdrawing the capillary tool 12 from the bond surface 16, while clamping the wire, such that the wire 10 simply detaches from the bonded ball 18. This clamp and detach method may also employ any of the known techniques of pre-weakening the wire at the appropriate point prior to detachment.
Another technique for detaching of the wire 10 from the bonded ball 18 involves withdrawing the capillary tool 12 from the bond surface 16, without the wire being clamped the wire 10. The wire 10 is then cut at the top of the bonded ball 18. Whichever detachment technique is employed, the wire 10 is then left extending beyond the tip of the capillary tool 12, in preparation for the formation of another ball, and the bonding process is then repeated for the next ball bond.
It will be appreciated by those skilled in the art that the method illustrated in Figures I to 4 is intended to be a non-limiting example of a known method of ball bonding and in particular flip chip ball bonding. It will be appreciated by those skilled in the art that other methods of flip chip and/or ball bonding exist and variations on the steps described above are possible.
As mentioned briefly above, one problem that is associated with bonding connections with different carriers is concerned with the different coefficients of thermal expansion (CTE's) of the carriers. By way of example, a silicon integrated circuit typically has a CTE of between 2-4, a ceramic interposer typically has a CTE in the range of 5-12 and a printed circuit board typically has a CTE of approximately 17. The differences in CTE values effectively limit the size of integrated circuits which are to be connected with a carrier. For example, mounting a silicon device on a ceramic carrier using known ball bonding techniques can lead to high stress levels being placed on the silicon device, because of the differences in thermal expansion of the two materials. Some of the factors that affect the maximum size of integrated circuit that can be bonded directly onto a high value CTE ceramic interposer using the described ball bonding technique include: the difference in CTE's of the carriers; the required operating temperature range; the height of the ball bonds; the materials used to form the ball bonds; and the presence of an underfill material and, if present, the composition of such underfill material.
In a method embodying the present invention, the steps illustrated in Figures 1 to 4 are used to bond a ball formed on the end of a wire to a bonding surface, as described. Figure 5 illustrates in more detail the point at which the ball 18 bonds to the bonding surface 16. The capillary tool 12 through which the wire 10 extends, vibrates the ball 18. The ultrasonic vibration of the ball 18 causes the ball to become plastic in nature, so that the ball spreads along the bonding surface 16 forming a bonding area 17. As is well known, the spreading of the ball causes the material of the ball to alloy with the material of the bonding surface thereby producing a bond between the ball and the surface. Figure 5 illustrates in more detail the capillary tool bore 11 which has a diameter d2 through which the wire having a diameter d, extends. In contrast with prior art ball bonding methods, the present invention does not simply stop the bonding process at this point and cut the wire from the ball, but rather continues to form a desired contact profile, as will be described in more detail below.
Figure 6 illustrates an example of a measured power profile used in a first method embodying the present invention.
The bonding process begins a time to, the point at which the ball 18 of Figures 3 and 4 is brought into contact with the bonding surface 16. At time to, power is applied to an actuator (not shown) which serves to vibrate the capillary tool 12, and hence the ball 18. Initially, the frictional force between the ball 18 and the surface 16 is low, which means the measured power at the capillary tool 12 rises to a maximum value P, due to resonance of the tool 12. At time fl, the frictional force between the ball 18 and the surface 16 has increased to such a level that the tool 12 no longer resonates. This results in a fall in measured power to a second level P2, at time t2. The ball and bonding surface are then effectively bonded to one another. However, due to variations in material properties, the power to the actuator is applied for a further time, until time h. In prior art methods, the power to the actuator is then switched off, and the measured power would decay. The reduction in power from P, to P2 during the period t, to h is commonly known and understood as 'lug down' by those skilled in the art. Typically, the period t, to t3 is in the region of 6-1OmS and the values of P, is typically in the region of 30 to 150 mW, and P2 to 10 to 20% lower than P, . At an appropriate time thereafter, the wire 10 can be operatively disconnected (not illustrated) from the ball 18 and the process repeats itself at the next bond surface location.
According to one embodiment of the present invention, rather than cutting the power to the actuator at time h, the power is applied for an additional time until time t4. The measured power, P2, during this time remains substantially constant, since the ball is bonded to the surface. The effect of the ultrasonic power during time h to 4 is to render the material plastic, such that the ball is extruded up into the bore of the capillary tool 12. Typically, the period t3 to t4 can be approximately 50mS, but this time is naturally dependent upon ball dimensions, ball material, power and the required pin height etc. At time t4, the power to the actuator is cut, and the measured power decays to zero. Thereafter, the wire 10 can be disconnected from the resulting pin, or pin-like, structure and the process repeats itself at the next bond surface location. One example of the resulting pin structure is shown in Figure 8, to be described in more detail below.
Figure 7 illustrates another example of a power profile used in a method embodying the present invention.
As will be appreciated, the power profile of Figure 7 follows that illustrated in Figure 6 until time %. At time t3 the applied power is cut and the measured power decays to zero, as in the prior art. In this embodiment of the invention, increased power is applied to the actuator at a time t5 after the first power application. This increased applied power results in a peak measured power P3 at a time t acting on the bonded ball.
Preferably, a greater load L' is applied to the ball 18 via the capillary tool 12 than in the previous case. By applying an increased load and increased ultrasonic power to the ball, the material in the ball 12 extruded up into the bore of the capillary tool 12. The increased load assists in extruding the ball material, whilst the increased ultrasonic power serves to prevent the ball material sticking to the bore of the tool, and serves to test the strength of the bond between the ball and the surface, as will be described below in more detail. The extruded material forms a pin or pin- like structure, as will be described below.
-g- As will be clear from Figure 7, bonding occurs during the time period to to t3 (the "bonding period"). The bonding apparatus and capillary tool 12 is then reset during the time period t3 to t5, which is typically 1 to 2 ms. and extrusion occurs during the time period t5 to t7 (the "extrusion period"). At the end of the extrusion period CA the applied power is cut and the measured power decays to zero. Thereafter, the wire 10 can be disconnected from the pin, or pin-like, structure and the process can then be repeated at the next bond location.
It will be readily appreciated by those skilled in the art that the load (L) exerted by the capillary tool 12 on the ball 18, can be altered. Typically, during the bonding period, a load in the region of 30 to 60g can be applied to the ball 18, and during the extrusion period, a load in the region of 80 to 1 00g can be applied to the ball 18.
In the embodiment of the present invention described with reference to Figure 7, the applied power, and hence the measured power level (P3) during the extrusion period is greater than that used during the bonding period. Using a higher power level during the extrusion period than that used during the bonding period, allows a shear test to be carried out on the bond automatically during the extrusion period. Carrying out a shear test on each bond in this way, with minimum increased time used is clearly advantageous, as will be appreciated by those skilled in the art.
In another, unillustrated, method embodying the present invention, the load L and applied power P are increased from the level set at time t3. Therefore, rather than the bonding apparatus being reset during the time period % to t5, the applied load and power are dynamically controlled so as to increase from time h. In such an embodiment, the extrusion period occurs sooner than in the previously described cases; which is advantageous. At the end of the extrusion period, the bonding apparatus and capillary tool 12 are reset, i.e. the applied power is cut, and thereafter, the wire 10 is disconnected from the pin, or pin-like, structure. The process can then be repeated at the next bond surface location.
It will be readily appreciated and understood by those skilled in the art that the process for determining the optimum parameters for forming a ball bond is essentially a matter of experiment. Such factors as adjusting: the downward load L on the ball; the applied power; the time of applying the power; and the background temperature, are among some of the many factors that have to be taken into consideration when forming such ball bonds. The exact parameters which optimise methods embodying the present invention can be found by experiment and testing.
Figures 8 and 9 illustrate a pin formed, using a method embodying the present invention. The pin has been formed using a capillary tool having a straight, or substantially straight, bore 11.
The pin 20 has a diameter d2, which substantially equals the diameter d12 of the bore 11 of the capillary tool 12. The diameter of pin is greater than the diameter d, of the wire from which it was formed. The height h of the pin is greater than, or at least equal to, the diameter c13 of the bonded ball. The bore 11 of the capillary tool 12 has an intermediate opening 13 which has a diameter larger than the bore 11. The intermediate portion 13 serves to hold the ball 18 in place during the bonding process. Figure 9 illustrates the removal of the wire 10 from the pin 20.
The aspect ratio (height to base diameter ratio) of pins manufactured according to a method embodying the present invention is preferably greater than or equal to 1.
Figures 10 and 11 illustrates a pin formed using a capillary tool having a tapered bore 15. In this case the bore tapers from a diameter d21 down to a diameter d2.
One advantage of having a tapered bore over a constant cross-section bore is that: the horizontal grip of the capillary tool 12 on the pin 20 will be greater; and the load L needed to extrude the pin 20 will be less. Exerting less load on the pin 20 results is less load being exerted on the bond surface 16, which is advantageous.
As can be seen from Figures 10 and 11, the diameter of the bore of the capillary tool 12 varies, between d2' and d2, along the height h of the pin 20. However, the pin 20 still has the desired characteristics of having a minimum diameter (d2) that is greater than the diameter d, of the wire 10 and a height h that is greater than, or at least equal to, the diameter of the bonded ball.
One preferred example application of these pins is for a series of pins to be bonded to a semiconductor device, such as a silicon device. The device can then be mounted on a carrier, for example a ceramic layer, by attaching the free ends of the pins to the carrier. Figure 12 illustrates bonding of a device to a carrier, the device having a number of pins 20 bonded thereto.
A feature of the present invention is that the length and the diameter d2 of the bore of the capillary tool 12, together with the profile of the bore, are sufficiently large enough so as to form a pin 20, or pin-like structure, having the required characteristics for its intended application. The height to base diameter ratio is determined by the likely stresses which will be transferred between the two surfaces to be connected by the pins. It is likely that a material which is malleable at normal operating temperatures would be used for the pins so that differences in thermal expansion can be allowed for by deformation of the pins. Such deformation reduces, or eliminates, the transferred stresses.
By way of a non-limiting example, the wire 10 could have a diameter d, of 25 microns, the bore of the capillary tool 12 could have a diameter d2 of 50 microns, the diameter d3 of the bonded ball could be microns and the height h of the pin could be 200 microns. The dimensions of the pin 20 are dependent upon the mechanical stresses that need to be counteracted and as such, the dimensions of the ball and the capillary tool 12 can be calculated so as to extrude a pin 20 with the required characteristics. Furthermore, the material from which the pin 20 is formed is preferably a malleable conductive material. Some non-limiting examples of such malleable conductive materials include aluminium, gold or copper, including alloys thereof.
In one exemplary method embodying the present invention pins are extruded, as described above, on only the good die that constitute a semiconductor wafer. There are obvious time and cost implications in only forming pins on these good die. A good die of the wafer can then be separated and attached to a suitable carrier by any one of the known bonding techniques, such as thermal compression or adhesive bonding, such bonding techniques being well known and understood by those skilled in the art. Alternatively, a complete semiconductor wafer could be bonded to a suitable electronic carrier.
Figure 12 illustrates bonding of an]C 24 to a carrier 26 using pins 20.
As illustrated in Figure 13 it is also possible to form aligned pins 20 on separate electronic carriers 24, 26 and then bond the pins together. An advantage of such a technique is that greater mechanical stresses can be compensated for since the overall pin height between the carriers is larger than with 5 single pins.
Furthermore, according to the present invention, it is also possible to form pins 20, or pin-like structures, on the same carrier, that have different heights (not illustrated).
Having bonded the semiconductor die/wafer to a carrier, for example, an appropriate underfill material can be applied so as to sea[ the area between the die and the carrier, such a technique, including its associated advantages, being understood and appreciated by those skilled in the art. The die and carrier can then be packaged accordingly.
It will be readily appreciated that the ball of material formed on the end of the wire can be of any suitable shape. The most common existing example shape is a sphere or near-spherical shape. Other shapes could be used. The one requirement is that the ball is an enlarged mass of material on the end of the wire which is able to be extruded into the required pin shape.
It will also be readily appreciated that the term "wire" can be construed to include filamentary material having any desired cross-section. Although most usual wires have circular cross-sections, methods embodying the present invention can be carried out using wires having any desired cross-section.

Claims (1)

  1. -13CLAIMS:
    1. A method of forming a connection on a surface of an electronic carrier, the method comprising: providing a malleable wire having a first diameter via a capillary tool having a bore of a second diameter, the second diameter being greater than the first diameter; forming a ball of material on an end of the wire; bonding the ball of material to a bonding surface of an electronic carrier to form a connection having a third diameter; extruding the ball of material into the bore of the of the capillary tool to form a pin structure; and disconnecting the wire from the pin structure.
    2. A method as claimed in claim 1, wherein the step of bonding the ball of material to the bonding surface includes: holding the ball of material in contact with the bonding surface using a predetermined load; and applying a first predetermined level of ultrasonic power to the ball of the material, for a first predetermined time period.
    3. A method as claimed in claim 2, wherein the step of extruding the ball of material into the bore includes: continuing to apply the first predetermined level of ultrasonic power to the ball of material for an additional second predetermined time period.
    4. A method as claimed in claim 2, wherein the step of extruding the ball of material into the bore includes: applying a second predetermined level of ultrasonic power to the ball of material for a third predetermined time period subsequent to the first predetermined time period.
    -145. A method as claimed in claim 1, wherein the bore has a substantially constant diameter along its length.
    6. A method as claimed in claim 1, wherein the bore is tapered such that its diameter reduces from an 5 initial diameter to the second diameter, along the length of the bore.
    7. A method as claimed in claim 1, wherein the pin structure is of a height greater than, or equal to, the third diameter.
    8. A method as claimed in claim 1, wherein the third diameter is greater than said second diameter.
    9. A method as claimed in claim 2, wherein the pin structure has a minimum diameter that is greater than said first diameter.
    10. A method as claimed in claim 1, wherein the wire is of a malleable conductive material.
    11. A method as claimed in claim 10, wherein the malleable conductive material is gold.
    12. A method as claimed in claim 10, wherein the malleable conductive material is a gold alloy, 20 13. A method as claimed in claim 10, wherein the malleable conductive material is copper.
    14. A method as claimed in claim 10, wherein the malleable conductive material is a copper alloy.
    15. A method as claimed in claim 1, wherein the carrier is an integrated circuit.
    16. A method as claimed in claim 1, wherein the carrier is an electronic interposer 17. A method as claimed in claim 1, wherein the carrier is a ceramic interposer. 30 -1518. A method as claimed in claim 1, wherein the carrier is a printed circuit board.
    19. A method as claimed in claim 1, wherein the carrier is an organic electronic carrier.
    20. A method as claimed in claim 15, wherein the integrated circuit is one of a plurality of integrated circuits on a semiconductor wafer.
    21. An electronic device comprising an integrated circuit and a carrier, the integrated circuit being attached to the carrier by at least one pin structure, formed and bonded to the integrated circuit in 10 accordance with a method as claimed in any one of the preceding claims.
    22. A pin for bonding to an integrated circuit, the pin comprising a main body portion, and a connection portion, wherein the pin is formed from a wire which has a diameter smaller than the diameter of the main body portion, and wherein the pin has an overall height greater than or equal to the diameter of 15 the connection portion.
    23. A pin as claimed in claim 22, formed in accordance with a method as claimed in any one of claims 1 to 20.
    24. An electronic device comprising integrated circuits having pins bonded thereto, each pin being as claimed in claim 22 or 23.
GB0028595A 2000-04-20 2000-11-23 Forming electrical/mechincal connections Expired - Fee Related GB2362035B (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
GB0108418A GB2362036A (en) 2000-04-20 2001-04-03 Forming pin contacts to electronic devices
PCT/GB2001/001737 WO2001082362A2 (en) 2000-04-20 2001-04-17 Process for forming electrical/mechanical connections
EP01921615A EP1275143B1 (en) 2000-04-20 2001-04-17 Process for forming electrical/mechanical connections
AU2001248586A AU2001248586A1 (en) 2000-04-20 2001-04-17 Process for forming electrical/mechanical connections
AT01921615T ATE371265T1 (en) 2000-04-20 2001-04-17 METHOD FOR PRODUCING ELECTRICAL/MECHANICAL CONNECTIONS
DE60130111T DE60130111D1 (en) 2000-04-20 2001-04-17 METHOD FOR PRODUCING ELECTRICAL / MECHANICAL CONNECTIONS
US10/257,842 US7137547B2 (en) 2000-04-20 2001-04-17 Process for forming electrical/mechanical connections

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0009839A GB2362504A (en) 2000-04-20 2000-04-20 Pin contacts

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GB0028595D0 GB0028595D0 (en) 2001-01-10
GB2362035A true GB2362035A (en) 2001-11-07
GB2362035B GB2362035B (en) 2002-08-14

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GB0009839A Withdrawn GB2362504A (en) 2000-04-20 2000-04-20 Pin contacts
GB0028595A Expired - Fee Related GB2362035B (en) 2000-04-20 2000-11-23 Forming electrical/mechincal connections

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2095473A (en) * 1981-03-20 1982-09-29 Philips Nv Providing raised contact portions on contact areas of a microelectronic device
EP0376294A1 (en) * 1988-12-28 1990-07-04 Hitachi, Ltd. Optically active compounds, liquid crystal compositions comprising said compounds, and liquid crystal optical modulators using said compositions
US5195237A (en) * 1987-05-21 1993-03-23 Cray Computer Corporation Flying leads for integrated circuits
US5558270A (en) * 1995-01-06 1996-09-24 Kulicke And Soffa Investments, Inc Fine pitch capillary/wedge bonding tool
US5871141A (en) * 1997-05-22 1999-02-16 Kulicke And Soffa, Investments, Inc. Fine pitch bonding tool for constrained bonding
US5906308A (en) * 1996-08-21 1999-05-25 Kabushiki Kaisha Shinkawa Capillary for use in a wire bonding apparatus
US5938105A (en) * 1997-01-15 1999-08-17 National Semiconductor Corporation Encapsulated ball bonding apparatus and method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2095473A (en) * 1981-03-20 1982-09-29 Philips Nv Providing raised contact portions on contact areas of a microelectronic device
US5195237A (en) * 1987-05-21 1993-03-23 Cray Computer Corporation Flying leads for integrated circuits
EP0376294A1 (en) * 1988-12-28 1990-07-04 Hitachi, Ltd. Optically active compounds, liquid crystal compositions comprising said compounds, and liquid crystal optical modulators using said compositions
US5558270A (en) * 1995-01-06 1996-09-24 Kulicke And Soffa Investments, Inc Fine pitch capillary/wedge bonding tool
US5906308A (en) * 1996-08-21 1999-05-25 Kabushiki Kaisha Shinkawa Capillary for use in a wire bonding apparatus
US5938105A (en) * 1997-01-15 1999-08-17 National Semiconductor Corporation Encapsulated ball bonding apparatus and method
US5871141A (en) * 1997-05-22 1999-02-16 Kulicke And Soffa, Investments, Inc. Fine pitch bonding tool for constrained bonding

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GB0009839D0 (en) 2000-06-07
GB2362035B (en) 2002-08-14
GB0028595D0 (en) 2001-01-10
GB2362504A (en) 2001-11-21

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Effective date: 20081123