Metal fusion bonding – With means to juxtapose and bond plural workpieces – Wire lead bonder
Reexamination Certificate
2001-08-30
2003-11-04
Dunn, Tom (Department: 1725)
Metal fusion bonding
With means to juxtapose and bond plural workpieces
Wire lead bonder
C228S045000, C228S057000
Reexamination Certificate
active
06641025
ABSTRACT:
TECHNICAL FIELD
This invention relates to integrated circuit fabrication, and, more particularly, to a method and tool to facilitate threading integrated circuit bond wires through capillary tubes in wire bond machines.
BACKGROUND OF THE INVENTION
Wire bond machines are typically used to attach bond wires between bond pads fabricated on integrated circuit dies and leadframes through which signals and power are routed to and from the integrated circuit. A typical wire bond machine
10
is shown in FIG.
1
. The wire bond machine
10
includes a spool
12
of bond wire
14
, which is typically gold wire having a diameter of about 1 mil (10
−3
inches). The wire
14
extends over a diverter
20
and passes through a housing
22
containing a sensor
24
and an air guide
26
. The sensor
24
and air guide
26
cooperate with each other in a conventional manner to draw the wire
14
from the spool
12
and maintain the wire
14
at the proper tension. The wire
14
then extends downwardly and passes through a nozzle
30
having a relatively large diameter to a guide tube
34
, which also has a relatively large diameter. The guide tube
34
has a flared upper end
36
that facilitates the threading of the wire
14
into the tube
34
. The wire
14
then extends through a gap
38
, typically 0.5-1.0 inches wide, and passes through a capillary tube. The capillary tube
40
typically has a diameter of about 3.0-3.5 mils. The capillary tube
40
is attached by a clamp
44
, to a transducer that produces ultrasonic force.
In operation, it is occasionally necessary to thread the bond wire
14
from the spool
12
to the capillary tube
40
such as, for example, if the supply of wire
14
from the spool
12
has been exhausted or the wire
14
breaks. Threading the wire
14
over the diverter
20
and through the housing
22
is fairly easy. Threading the wire
14
through the nozzle
30
and guide tube
34
is somewhat more difficult, but because of the relatively large diameters of the nozzle
30
and guide tube
34
, can generally be accomplished by a skilled operator fairly easily in relatively little time. However, it is substantially more difficult to thread the wire
14
into an end
48
in the capillary tube
40
because of the relatively small diameter of the capillary tube
40
. The guide tube
34
is somewhat effective in guiding the wire
14
to the general vicinity of the end
48
of the capillary tube
40
, but, because of the gap
34
, the wire
14
is easily deflected from the entrance to the capillary tube
40
. For example, there may be air currents present that, although slight, are sufficient to deflect the wire
14
away from the end
48
of the capillary tube
40
. Even the breath of an operator threading the wire
14
can be sufficient to deflect the wire
14
away from the end
48
of the capillary tube
40
. As a result, it is invariably necessary for the operator to manually guide the wire
14
into the end
48
of the capillary tube
40
.
The operator typically guides the wire
14
into the end
48
of the capillary tube
40
by grasping the wire
14
with a tweezers (not shown) while viewing the end of the wire
14
through a magnifier (not shown), such as a microscope (not shown). Successfully guiding the wire
14
into the end
48
of the capillary tube
40
in this manner requires a great deal of skill and manual dexterity, and usually requires a great deal of time. During the time the operator is threading the wire
14
through the capillary tube
40
, the bond machine
10
may not be used for fabricating integrated circuits. The difficulty in threading the wire
14
through the capillary tube
40
not only results in excessive down-time of the bond machine
10
, but may also cause excessive down-time of an integrated circuit fabrication line in which the wire bond machine
10
is used. Further, the skill required to manually thread the wire
14
through the capillary tube
40
reduces the availability of operators capable of operating the wire bond machine
10
and, because manually dexterity and vision may decline with age, may shorten the careers of such operators.
There is therefore a need for a device and method to facilitate the threading of bond wires through capillary tubes, thus reducing the time and skill level required to thread bond wires through a bond machine.
SUMMARY OF THE INVENTION
A capillary threading tool is used with a wire bond machine to thread bond wire in though a capillary tube positioned below a guide tube by a gap. The capillary threading tool includes a handle connected to a body portion that is inserted into the gap. The body portion includes a slot through which the bond wire passes between the guide tube and capillary tube. The slot has first and second portions separated from each other along the length of the bond wire. The first portion of the slot has a width that is smaller than the outside diameter of the capillary tube, and the second portion of the slot has a width that is approximately equal to the outside diameter of the capillary tube. The body portion is placed in the gap with the capillary tube inserted into the second portion of the slot beneath the first portion of the slot so that the first portion of the slot substantially fills the gap. The first and second portions of the slot terminate in respective first and second slot ends that are substantially aligned with each other. The capillary tube is placed against the end of the second portion of the slot to align the end of the first portion of the slot with the capillary tube. As a result, the end of the first portion can be used to guide the bond wire into the capillary tube.
REFERENCES:
patent: 5906706 (1999-05-01), Farassat
patent: 6100511 (2000-08-01), Kempe
patent: 6206275 (2001-03-01), Biggs
patent: 6318704 (2001-11-01), Christenson
patent: 6502738 (2003-01-01), Mochida et al.
Pfankuch Daniel A.
Stilwell Michael
Tucker John
Cooke Colleen P.
Dunn Tom
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