Wire bonding methods and apparatus for heat sensitive metallization using a thermally insulated support portion

A wire bonding apparatus has a first support arrangement for supporting a first integrated circuit package component. A second support arrangement is configured to supporting a second integrated circuit package component. The second support arrangement includes at least a portion of a heating arrangement for heating certain portions of the second component. At least portions of the first support arrangement are thermally insulated from the second support arrangement such that at least certain portions of the first component may be maintained at a temperature substantially lower than the temperature of the heated portions of the second component. The apparatus may be used in method of forming a bonding wire for electrically connecting a first contact on a first integrated circuit package component to a second contact on a second integrated circuit package component. The method includes the steps of supporting and holding the first component and the second component in a desired position. Certain regions of the second component, including the second contact, are heated to a desired temperature while maintaining the temperature of at least certain portions of the first component, including the first contact, at a temperature substantially lower than the heated regions of the second component. A bonding wire is formed that electrically connects the first contact on the first component to the second contact on the second component.

BACKGROUND OF THE INVENTION 
The present invention relates generally to wire bonding apparatus and 
methods used in the manufacture of integrated circuit packages. More 
specifically, the present invention relates to methods and apparatus used 
to wire bond an integrated circuit package component such as a die that 
utilizes heat sensitive contacts such as copper contacts. 
The semiconductor industry has been moving continuously toward smaller and 
faster semiconductor devices with higher transistor density and increasing 
numbers of input/output connections. These trends have led to the desire 
to replace the more common aluminum metallization layers within 
semiconductor devices with copper containing metallization layers. As is 
well known to those skilled in the art, this use of copper rather than 
aluminum provides substantial benefits such as higher speed and improved 
conductivity, and reduces the problems caused by the inductance and 
capacitance of the features formed in the metallization layer. 
Although the use of copper metallization layers in semiconductor devices 
improves the performance of the device, these devices are difficult to 
package using conventional wire bonding techniques. This difficulty is 
mainly due to the fact that, compared to conventional aluminum 
metallization layers, copper metallization layers oxidize very quickly 
when exposed to oxygen in the air. This is especially the case when copper 
is exposed to air at an elevated temperature as is typically required 
during conventional wire bonding processes. 
Wire bonding remains the most common chip interconnecting method for fine 
pitch semiconductor devices. Gold or aluminum wire is commonly used to 
connect an input/output terminal pad of the semiconductor die to a lead of 
a interconnecting substrate such as a leadframe. Typically, a ball bond is 
used to connect a first end of a bonding wire to the input/output terminal 
pad while a wedge bond, also called a stitch bond, is used to connect the 
bonding wire to the lead of the leadframe. Conventional wire bonding 
apparatus utilize a capillary that is driven by the wire bonding apparatus 
to form the bonding wire. The capillary is also used for both the ball 
bonding and the stitch bonding processes. 
For illustrative purposes, a conventional wire bonding apparatus 100 that 
is used to wire bond a conventional integrated circuit die to the leads on 
a leadframe will be described with reference to FIGS. 1-3. As shown in 
FIG. 1, wire bonding apparatus 100 includes a heater block 102 for 
supporting leadframe 104 and an integrated circuit die 106. Die 106 
includes a plurality of input/output terminal pads 108 that are to be 
electrically connected to a plurality of associated leads 110 on leadframe 
104 using an array of bonding wires 112 that are formed during the wire 
bonding process. As shown in FIG. 1, bonding wires 112 are attached to 
associated input/output terminal pads 108 using a ball bond 114. The other 
end of each bonding wire 112 is attached to an associated lead 110 using a 
stitch bond 116. 
Leadframe 104 is held in position using a window clamp 118 which 
mechanically clamps leadframe 104 against heater block 102. Heater block 
102 includes a vacuum port 120 having a vacuum cup 122 that is used to 
securely hold die 106 in place during the wire bonding process. Heater 
block 102 also includes heating elements 124 that run through heater block 
102. As described in more detail hereinafter, heating elements 124 are 
used to heat heater block 102, and therefore leadframe 104 and die 106, to 
a desired temperature to aid in the wire bonding process. 
Wire bonding apparatus 100 further includes a capillary 126 that has a 
longitudinally extending wire feed bore 128 that is used to extrude 
bonding wires 112. To assist in the wire bonding process, wire bonding 
apparatus 100 is capable of placing a desired downward force on capillary 
126 during the process of forming ball bond 114 and stitch bond 116. 
Apparatus 100 also typically is capable of delivering ultrasonic energy to 
the bonding region through capillary 126 to enhance the bonding process. 
As mentioned above, heater block 102 is heated to a desired temperature, 
typically a temperature greater than about 150 degrees centigrade, to aid 
in the bonding process. 
FIGS. 2A-C briefly illustrate the basic steps involved in forming a bonding 
wire using capillary 126. FIG. 2A is a close up partial cross sectional 
view of capillary 126. As illustrated in FIG. 2A, a free air ball 130 of a 
bonding wire material such as gold or aluminum is formed at a distal end 
132 of capillary 126. This is typically accomplished using an electronic 
flame off mechanism 134 which applies energy to distal end 132 of 
capillary 126. Once free air ball 130 is formed, it is used to form ball 
bond 114 on input/output terminal pad 108. FIG. 2B illustrates a close up 
vertical cross sectional view of capillary 126 as it is being used to form 
ball bond 114. As mentioned above, a combination of heat, pressure from 
capillary 126, and ultrasonic energy are used to attach ball bond 114 to 
pad 108. 
Once ball bond 114 is attached to pad 108, bonding wire 112 is extruded 
through wire feed bore 128. With an appropriate length of bonding wire 
extruded, bonding wire 112 is stitch bonded to an associated lead 110 on 
leadframe 104. FIG. 2C illustrates a close up vertical cross sectional 
view of capillary 126 as it is being used to form stitch bond 116 on lead 
110. Again, a combination of heat, pressure, and ultrasonic energy are 
used to make stitch bond 116. 
Traditionally, the above described wire bonding process requires a 
substantial amount of heat in order to insure good quality bonds at ball 
bond 114 and stitch bond 116. Typically temperatures of greater than 150 
degrees centigrade are required. When utilizing heat sensitive 
metallization layers such as copper or copper alloys to form the 
input/output terminal pads 108 on die 106, these relatively high 
temperatures accelerate the oxidation of the copper pads which can prevent 
the formation of a good reliable bond between ball bond 114 and pad 108. 
Therefore, to reduce this problem, it is desirable to develop methods and 
apparatus capable of forming ball bonds at a reduced temperature. 
One approach to reducing the amount of heat required to form ball bonds is 
described in detail in two copending U.S. Patent Applications, which 
applications are incorporated herein by reference. These two U.S. patent 
applications are: Ser. No. 08/784,271, entitled METHOD AND APATUS FOR 
FINE PITCH WIRE BONDING, attorney docket number NS3463/NSC1P087; and Ser. 
No. 08/890,354, entitled ENCAPSULATED BALL BONDING APATUS AND METHOD, 
attorney docket number NS3681/NSC1P098. 
FIG. 3 illustrates a close up partial cross sectional view of a capillary 
140 similar to capillary 126 described above. However, capillary 140 
includes a specific tip configuration such as that described in detail in 
the above referenced patent applications. This specific tip configuration, 
which is referred to as encapsulated ball bonding, allows capillary 140 to 
be used to form a ball bond 144 without requiring as much heat as is 
typically required to form reliable ball bonds. In fact, as will be 
described in more detail hereinafter, applicants have found that the 
encapsulated ball bonding methods and apparatus may be used to form high 
quality ball bonds without requiring any substantial heating of the 
contacts to which the ball bonds are to be attached 
To summarize the above referenced patent applications, the encapsulated 
ball bonding apparatus and methods will be briefly described with 
reference to FIG. 3. As shown in FIG. 3, capillary 140 has a 
longitudinally extending wire feed bore 141 that is used to extrude 
bonding wires 112. Capillary 140 also has a cavity 142 formed into its 
tip. Cavity 142 has a cavity diameter 143 and is shaped and sized such 
that cavity 142 substantially encapsulates and is capable of molding a 
ball bond 144. Among other things, this configuration allows capillary of 
this design to deliver ultrasonic energy to ball bonds more effectively 
than conventional tip configurations. Because of this, reliable ball bonds 
may be formed without requiring any substantial heating of the 
input/output terminal pads to which the ball bonds are to be attached. 
In a specific example, a number of experiments have been successfully 
performed using a model 3006FPX wire bonding machine available from ESEC. 
Using such a machine and a capillary having a 1.0 mil gold bonding wire 
and a cavity diameter of about 1.6 mil, bonding times on the order of 15 
milliseconds at 14% power worked well. In the experiment, the bonding 
temperature was about 120 degrees centigrade and the bonding force exerted 
downward on the ball bond during the bonding process was about 100 mN. Of 
course, the settings used for various applications may be widely varied. 
Because the above described encapsulated ball bonding approach does not 
require heating of the contact to which the ball bond is to be attached, 
this approach is well suited to ball bonding on heat sensitive 
metallization layers such as cooper or copper alloys. By eliminating the 
need to heat the contact to which the ball bond is to be attached, the 
amount of oxidation that occurs during the overall bonding process may be 
substantially reduced. However, although the encapsulated ball bonding 
approach works well to produce a ball bond without requiring any 
substantial heating, this is not the case for forming good quality stitch 
bonds. In the case of stitch bonds, the encapsulated ball bonding approach 
still appears to require the heating of the lead to which the stitch bond 
is to be attached in order to provide reliable connections. 
To date, wire bonding is one of the most cost effective and popular 
packaging methods of packaging integrated circuit die. Because of the 
popularity of this packaging approach, conventional wire bonding equipment 
is readily available. Accordingly, it is desirable to provide methods and 
apparatus that will allow conventional wire bonding apparatus to be 
modified so that integrated circuit packages using heat sensitive 
metallization layers such as copper or copper alloy may be reliably 
assembled. The present invention provides improved wire bonding methods 
and wire bonding apparatus that substantially reduce the oxidation problem 
associated with the use of higher performance heat sensitive metallization 
layers such as copper and copper alloys. This allows integrated circuit 
packages using the higher performance materials to be reliably assembled 
using cost effective wire bonding methods and apparatus in accordance with 
the invention. 
SUMMARY OF THE INVENTION 
As will be described in more detail hereinafter, a method of forming a 
bonding wire for electrically connecting a first contact on a first 
integrated circuit package component to a second contact on a second 
integrated circuit package component is disclosed herein. The method 
includes the step of supporting and holding the first component and the 
second component in a desired position. Certain regions of the second 
component, including the second contact, are heated to a desired 
temperature while maintaining the temperature of at least certain portions 
of the first component, including the first contact, at a temperature 
substantially lower than the heated regions of the second component. A 
bonding wire is formed that electrically connects the first contact on the 
first component to the second contact on the second component. 
In one embodiment, the first component is an integrated circuit die, the 
first contact is a heat sensitive metal input/output terminal pad on the 
die, the second component is a leadframe, and the second contact is a 
contact pad located on an electrically conductive lead of the leadframe. 
The step of forming the bonding wire includes the steps of using a 
capillary driven by a wire bonding machine to form a ball bond attached to 
the first contact of the first component. The capillary has a recessed tip 
that defines a cavity. The cavity is sized and shaped such that it is able 
to substantially encapsulate and mold the ball bond into a desired ball 
bond shape during the step of using the capillary to form the ball bond on 
the first contact of the first component. The capillary is also used to 
form a bonding wire extending from the ball bond and to stitch bond the 
bonding wire to the second contact of the second component. 
In one version of this embodiment, the first contact on the first component 
is a copper contact and the step of forming a ball bond on the first 
contact includes the step of using ultrasonic energy to attach the ball 
bond to the first contact on the first component. Preferably, the step of 
forming the ball bond includes the step of forming the ball bond at a 
temperature of less than about 110 degrees centigrade. In some cases, the 
step of forming the ball bond includes the step of forming the ball bond 
attached to the first contact using substantially only ultrasonic energy 
without substantially heating the capillary or first contact in order to 
assist in the formation and attachment of the ball bond to the first 
contact. 
In another embodiment, the step of supporting and holding the first and 
second component includes the step of supporting the first and second 
component on a heater block. The heater block includes a first portion for 
supporting the first component and a second portion that is thermally 
insulated from the first portion for supporting the second component, the 
second portion of the heater block including at least a portion of a 
heating arrangement for heating the second portion of the heater block. In 
one version of this embodiment, the heating arrangement includes a heating 
element formed into the heater block. In this version, the step of heating 
certain portions of the second component includes the step of using the 
heating element to heat the second portion of the heater block on which 
the second component is supported thereby heating certain portions of the 
second component. Alternatively, in another version, the heating 
arrangement includes a primary coil and a secondary coil. In this case, 
the step of heating certain portions of the second component includes the 
step of using the primary and secondary coils to inductively heat the 
certain portions of the second component. 
In another embodiment, the step of supporting and holding the first and 
second component includes the step of using a window clamp to hold the 
second component in position on the heater block. The window clamp has an 
opening formed into the window clamp for allowing access to the first and 
second contacts during the step of forming the bonding wire. The window 
clamp also includes an arrangement for directing a flow of gas over the 
first component during the step of forming the bonding wire. The method 
further includes the step of directing a flow of inert cooling gas over 
the first component during the step of forming the bonding wire. 
In one embodiment, the heating step includes the step of heating the 
certain regions of the second component to a temperature greater than 
about 150 degrees centigrade while maintaining the temperature of at least 
certain portions of the first component at a temperature less than about 
110 degrees centigrade. 
A wire bonding apparatus is also disclosed. The apparatus includes a first 
support arrangement for supporting a first integrated circuit package 
component. The apparatus also includes a second support arrangement for 
supporting a second integrated circuit package component. The second 
support arrangement includes at least a portion of a heating arrangement 
for heating certain portions of the second component. At least portions of 
the first support arrangement are thermally insulated from the second 
support arrangement such that at least certain portions of the first 
component may be maintained at a temperature substantially lower than the 
temperature of the heated portions of the second component. 
The wire bonding apparatus may further include a window clamp for holding 
the second component in position on the second support arrangement. The 
window clamp has an opening formed into the window clamp for allowing 
access to portions of the first and second components during a wire 
bonding process. The window clamp also has an arrangement for directing a 
flow of a cooling gas over the first component during the wire bonding 
process. This allows portions of the second component to be heated to a 
desired temperature while maintaining the temperature of portions of the 
first component at a temperature substantially lower than the heated 
portions of the second component. 
In one embodiment of the apparatus, the first support arrangement and the 
second support arrangement are formed as part of a heater block. The 
heater block has a first and a second portion. The second portion includes 
at least a part of a heating arrangement for heating at least certain 
parts of the second portion of the heater block. The first portion of the 
heater block is thermally insulated from the second portion such that the 
second portion of the heater block may be heated to a desired temperature 
while maintaining the temperature of the first portion of the heater block 
at a temperature substantially lower than the temperature of the second 
portion of the heater block. In one embodiment, the first portion of the 
heater block is thermally insulated from the second portion of the heater 
block by an air gap located between the first and second portions of the 
heater block. 
The second portion of the heater block may be configured to support a 
leadframe of an integrated circuit package and the first portion of the 
heater block may be configured to support an integrated circuit die. This 
configuration allows at least certain regions of the leadframe to be 
heated to a desired temperature while maintaining the temperature of the 
die at a temperature substantially lower than the heated regions of the 
leadframe. 
The heating arrangement may include a heating element formed into the 
second portion of the heater block. Alternatively, the heating arrangement 
may include a primary coil and a secondary coil with one of the coils 
being formed into the second portion of the heater block. With this 
arrangement, the primary and secondary coils are used to inductively heat 
at least certain parts of the second portion of the heater block. 
In a preferred embodiment, the heating arrangement is configured to heat at 
least a part of the second portion of the heater block to a temperature 
greater than about 150 degrees centigrade. Also, the first portion of the 
heater block is thermally insulated from the second portion of the heater 
block such that the first portion of the heater block may be maintained at 
a temperature of less than about 110 degrees centigrade. 
A heating arrangement for use in a wire bonding apparatus is also 
disclosed. The heating arrangement includes a primary coil and a secondary 
coil. The secondary coil has a portion of the secondary coil positioned in 
close proximity to at least a portion of the primary coil. An A/C power 
source is electrically connected to the primary coil for driving the 
primary coil such that the primary coil and secondary coil interact to 
inductively heat certain materials that may be positioned between the 
primary and secondary coils.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the following detailed description of the present invention, several 
specific embodiments are set forth in order to provide a thorough 
understanding of the invention. However, as will be apparent to those 
skilled in the art, the present invention may be practiced without these 
specific details or by using alternative elements or processes. In other 
instances, well known processes, procedures, components, and circuits have 
not been described in detail so as not to unnecessarily obscure aspects of 
the present invention. 
Referring initially to FIG. 4, a wire bonding apparatus 200 designed in 
accordance with the invention will be described. For illustrative 
purposes, an example of a system similar to that described above in the 
background will be described. As shown in FIG. 4 and in accordance with 
the invention, wire bonding apparatus 200 includes a first support 
arrangement 202 for supporting a first integrated circuit package 
component. In this example, the first integrated circuit package component 
takes the form of integrated circuit die 106 as described for FIG. 1 and 
first support arrangement 202 takes the form of a first portion 204 of a 
heater block 206. Apparatus 200 also includes a second support arrangement 
208 for supporting a second integrated circuit package component. In this 
case the second integrated circuit package component is leadframe 104 as 
described for FIG. 1 and second support arrangement 208 is a second 
portion 210 of the heater block 206. 
Although the first and second integrated circuit package components are 
described in this example as being a die and a leadframe, it should be 
understood that this is not a requirement of the invention. Instead, these 
components may be any desired integrated circuit package components that 
are to be interconnected using a bonding wire. For example, they may be 
two die that are to be interconnected using bonding wires. Also, although 
support arrangements 202 and 208 have been described as first and second 
portions 204 and 210 of a heater block 206, it should be understood that 
other support arrangements would also fall within the scope of the 
invention. 
In accordance with the invention, first portion 204 and second portion 210 
of heater block 206 are thermally insulated from one another. In the 
example shown in FIG. 4, this thermal insulation is provided by an air 
space 212 between the first portion 204 and second portion 210. 
Alternatively, solid insulating material or any other suitable and readily 
providable insulating arrangement may be utilized to thermally insulate 
the first and second portions of the heater block and still remain within 
the scope of the invention. The thermally insulated first portion of the 
heater block is sometimes referred to herein as a "floating pedestal" 
since it supports and thermally insulates a portion of the component being 
wire bonded during wire bonding. 
Apparatus 200 also includes a heating arrangement 214 for heating at least 
portions of second portion 210 of heater block 206. This heating 
arrangement may be any suitable and readily providable heating 
arrangement. In the example shown in FIG. 4, heating arrangement 214 
includes a heating element 216. Heating element 216 runs through heater 
block 206 such that it is capable of heating second portion 210 of heater 
block 206 and therefore capable of heating certain portions of leadframe 
104 including leads 110. However, since first portion 204 of heater block 
206 is thermally insulated from second portion 210 by air space 212, 
heating element 216 does not substantially heat first portion 204. Also, 
since die 106 is supported by first portion 204 of heater block 206, die 
106 is not substantially heated by heating element 216. Therefore, in 
accordance with the present invention, the above described configuration 
of apparatus 200 allows certain portions of leadframe 104 including leads 
110 to be heated to a desired temperature while maintaining die 106 at a 
temperature substantially lower than the heated portions of leadframe 104. 
As describe above for FIG. 1, die 106 includes input/output terminal pads 
108 that are to be electrically connected to associated leads 110 on 
leadframe 104 using bonding wires 112. For the example illustrated in FIG. 
4, bonding wires 112 are formed during the wire bonding process using 
encapsulated capillary 140 as described above for FIG. 3. Bonding wires 
112 are attached to associated input/output terminal pads 108 using a ball 
bond 144. The other end of each bonding wire 112 is attached to an 
associated lead 110 using a stitch bond 116. 
In a similar manner to that described above for FIG. 1, leadframe 104 is 
held in position using a window clamp 118 which mechanically clamps 
leadframe 104 against heater block 206. As also described above for heater 
block 102, heater block 206 includes vacuum port 120 having vacuum cup 122 
that is used to securely hold die 106 in place during the wire bonding 
process. Wire bonding apparatus 200 further includes capillary 140 that 
has longitudinally extending wire feed bore 141 that is used to extrude 
bonding wires 112. To assist in the wire bonding process, wire bonding 
apparatus 200 is capable of placing a desired downward force on capillary 
140 during the process of forming ball bond 144 and stitch bond 116. 
Apparatus 200 also is capable of delivering ultrasonic energy to the 
bonding region through capillary 140 to enhance the bonding process. 
Now that the basic configuration of wire bonding apparatus 200 has been 
described, the process of forming bonding wires in accordance with the 
invention using such an apparatus will be described with reference to the 
flow chart of FIG. 5. FIG. 5 illustrates the basic steps involved in 
forming a bonding wire using apparatus 200 of FIG. 4. As indicated by 
block 302, the process starts by supporting a first and a second 
integrated circuit package component in a desired position. As described 
above, these components include associated contacts that are to be 
interconnected using bonding wires formed by apparatus 200. 
Initially, in accordance with the method of the present invention, certain 
portions of the second integrated circuit package component, for example 
portions of a leadframe, are heated to a desired temperature. This 
temperature is a temperature that is sufficient to assure that a good 
quality stitch bond may be made on the contact of the second component. 
Typically this temperature would be greater than about 150 degrees 
centigrade. Although the specific temperature of 150 degrees centigrade is 
given as an example, it should be understood that this temperature is not 
a requirement of the invention. 
As described above, the first integrated circuit package component, for 
example a die including copper metal input/output terminal pads, is 
maintained at a temperature substantially lower than the temperature of 
the heated portions of the second integrated circuit package component. 
This is accomplished by using an apparatus in accordance with the 
invention that thermally insulates the first portion of the heater block 
from the second portion of the heater block. In a specific example, the 
die and the copper input/output terminal pads are maintained at a 
temperature of less than about 110 degrees centigrade. In other 
embodiments, the die and the input/output terminal pads may be maintained 
at a temperature near ambient temperatures. Again, although specific 
temperatures have been given as an example, it is to be understood that 
the present invention would equally apply regardless of the specific 
temperatures used so long as there is a substantial temperature 
differential between the temperature of the contacts of the second 
component and the contacts of the first component. 
Once the components are heated to their desired temperatures, the wire 
bonding process is performed as indicated by blocks 306, 308, 310 and 312 
of FIG. 5. Initially, a free air ball of a bonding wire material such as 
gold is formed at the distal end of capillary 140 as described earlier for 
FIG. 2A. This is typically accomplished using an electronic flame off 
mechanism which applies energy to the distal end of the capillary. Once 
the free air ball is formed, it is used to form ball bond 144 on 
input/output terminal pad 108 as described above for FIG. 3. As mentioned 
above, because encapsulated capillary 140 is used to form ball bond 144, 
the temperature required for forming this bond is substantially reduced. 
In fact, applicants have found that the proper combination of pressure 
from capillary 140 and ultrasonic energy may be used to attach ball bond 
144 to pad 108 without requiring pad 108 to be heated. 
Once ball bond 144 is attached to pad 108, bonding wire 112 is extruded 
through wire feed bore 141 as indicated in block 308 of FIG. 5. With an 
appropriate length of bonding wire extruded, bonding wire 112 is stitch 
bonded to an associated lead 110 on leadframe 104 as indicated by block 
310 of FIG. 5. This procedure is illustrated in FIG. 2C. As described 
above, stitch bond 116 requires a combination of heat, pressure, and 
ultrasonic energy to form a reliable stitch bond 116. Since, leads 110 of 
leadframe 102 are heated to a desired temperature as indicated in block 
304 of FIG. 5, this approach to wire bonding is able to produce reliable 
stitch bonds on leads 110. As indicated in block 312, steps 306, 308, and 
310 are repeated until all of the desired bonding wires are formed 
interconnecting die 106 to leadframe 104. 
Because copper input/output terminal pad 108 is maintained at a temperature 
substantially lower than the temperature of leads 110, the amount of 
oxidation of copper pad 108 is substantially reduced. By reducing the 
oxidation levels, more reliable ball bonds are produced compared to those 
that would be possible if copper pads 108 were heated to the same 
temperatures as leads 110 as is the case in conventional wire bonding 
processes. 
Referring now to FIG. 6, several alternative configurations for a wire 
bonding apparatus 400 in accordance with the invention will be described. 
FIG. 6 illustrates another embodiment of the invention that incorporates a 
novel window clamp arrangement 402 that aids in maintaining die 106 at a 
temperature substantially lower than the heated portions of leadframe 104. 
As described above for apparatus 200, apparatus 400 includes a heater 
block 206 having a first portion 204 that is thermally insulated from 
second portion 210. However, in this embodiment window clamp arrangement 
402 includes a gas directing arrangement 404 for directing a flow of gas 
over die 106. 
In the embodiment shown in FIG. 6, gas directing arrangement 404 includes a 
lower plate 406 and an upper plate 408. Lower plate 406 functions in a 
manner similar to a conventional window clamp such as window clamp 118 
described above. That is, the primary purpose of lower plate 406 is to 
hold leadframe 104 in place. Upper plate 408 provides a completely 
separate function. As shown in FIG. 6, upper plate 408 is configured to 
direct a flow of gas 410 over die 106 and around the first portion 204 of 
heater block 206 as indicated by arrows 410. This flow of gas is able to 
provide two different functions. 
The first function provided by window clamp arrangement 402 is that gas 410 
acts as a coolant to assist in maintaining the first portion 204 of heater 
block 206 and die 106 at a temperature substantially lower than the 
temperature of the heated portions 210 of heater block 206. To further 
assist in this cooling effect, first portion 204 of heater block 206 may 
include a plurality of openings 412 formed into first portion 204. These 
openings increase the surface area of first portion 204 which improves the 
cooling effect of gas 410. That is, the openings 412 form channels in the 
pedestal 204 through which the cooling gas 410 may pass to better cool the 
pedestal relative to the second portion 210 of the heater block 206. 
In the second function, gas 410 may be an inert gas such as nitrogen. Since 
gas 410 is directed over die 106 as indicated in FIG. 6, this flow of 
inert gas over die 106 and pads 108 creates a localized region of inert 
gas surrounding die 106 that has a substantially reduced concentration of 
oxygen. By increasing the concentration of inert nitrogen gas and reducing 
the concentration of oxygen in the localized region surrounding die 106, 
the amount of oxidation that may occur on pads 108 is further reduced. 
Although second portion 210 of heater block 206 has been described as 
including a heating element, this is not a requirement. Instead, any 
suitable arrangement for heating second portion 210 may by utilized. FIG. 
6 illustrates an alternative embodiment of a heating arrangement 420 that 
uses inductive heating to heat lead 110 of leadframe 104. In this 
embodiment, second portion 210 of heater block 206 includes at least 
portions of a primary coil 422. Additionally, lower plate 406 of window 
clamp arrangement 402 includes at least portions of a secondary coil 424 
that is positioned in close proximity to portions of primary coil 422. In 
this embodiment, primary coil 422 is driven by a suitable and readily 
providable A/C power source 426 in a way that causes primary coil 422 and 
secondary coil 424 to interact, thereby inductively heating leads 110 of 
leadframe 104. This inductive heating approach allows for very localized 
heating of leads 110 and improves the efficiency of the overall wire 
bonding apparatus 400. 
Referring now to FIG. 7, one final embodiment of a wire bonding apparatus 
500 designed in accordance with the invention will be described. In this 
embodiment, apparatus 500 is designed to operate on leadframes that are 
arranged in a strip or magazine 502. That is, multiple leadframes 104 are 
formed within a single strip or sheet 502 of substrate material. 
As shown in FIG. 7, apparatus 500 includes heater block 206 having first 
and second portions 204 and 210 as described above. However, in this 
embodiment, heater block 206 includes additional thermally insulating 
regions 504. Insulating regions 504 are located in heater block 206 such 
that, as leadframe strip or magazine 502 is advanced as each die 106 
completes the wire bonding procedure, that die advances to a location 
above one of insulating regions 504. Also, each die is positioned over 
another insulating region 504 prior to being positioned over the first 
portion 204 of heater block 206. This successive positioning of the die 
over thermally insulated regions prevents the heating of the die as it is 
queued to the wire bonding position on apparatus 500. 
Apparatus 500 also includes a window clamp arrangement 506 similar to that 
described above for window clamp arrangement 402. That is window claim 
arrangement 506 includes a lower plate 508 and upper plate 510. However, 
in this embodiment, lower plate 508 and upper plate 510 cooperate to form 
openings 512 above insulating regions 504. These openings 512 allow inert 
gas 410 to flow over die 106 as die 106 are awaiting the wire bonding 
process and after die 106 have completed the wire binding process. In this 
embodiment, a plurality of feed hoses 514 are used to supply gas 410 to 
apparatus 500. 
Although window clamp arrangement 506 has been described as including a 
lower plate and an upper plate, this is not a requirement of the 
invention. Instead, any suitable clamping arrangement may be utilized and 
any suitable arrangement for directing a flow of gas over the die may be 
utilized. Any of these various combinations of clamping and gas feed 
arrangements would equally fall within the scope of the present invention. 
Although only a few specific embodiments of a wire bonding apparatus and 
methods of using the apparatus in accordance with the invention have been 
described in detail, it should be understood that the apparatus of the 
invention may take on a wide variety of different configurations that may 
be used in a wide variety of specific methods of the present invention. 
All of these various apparatus and methods would equally fall within the 
scope of the invention so long as the heat sensitive metallization 
contacts of the first integrated circuit package component are maintained 
at a temperature substantially lower than the temperature of the heated 
portions of the second integrated circuit package component. Also, 
although only a few specific embodiments of methods of the invention have 
been described, it is to be understood that the methods of the present 
invention may be embodied in a wide variety of alternative forms and still 
remain within the scope of the invention. Any of these various embodiments 
would equally fall within the scope of the invention so long as the 
temperature differential is maintained between the ball bond contact and 
the stitch bond contact. 
Although only certain conventional integrated circuit package components 
have been described as being used with the novel method of the invention, 
it should be understood that the present invention may take on a wide 
variety of specific configurations using a variety of other conventional 
components and still remain within the scope of the present invention. 
Therefore, the present examples are to be considered as illustrative and 
not restrictive, and the invention is not to be limited to the details 
given herein, but may be modified within the scope of the appended claims.