Wire bonding apparatus

A wire bonding machine includes (1) a support structure for supporting a work piece and (2) a pre-heat structure for supporting the work piece during a pre-heat operation. The pre-heat structure is moveable with respect to the support structure.

FIELD OF THE INVENTION

The present invention relates to wire bonding equipment used in semiconductor processing. More particularly, the present invention relates to a material handling system component of a wire bonding system.

BACKGROUD OF THE INVENTION

The present invention is an improvement which may be applied to known wire bonding equipment (or new wire bonding equipment) such as the Maxμm™ automatic wire bonder available from Kulicke and Soffa Industries, Inc. of Willow Grove, Pa. Such wire bonding equipment typically includes a material handling system which operates to supply and remove work pieces, or lead frames, to a bonding station having an indexer. During the wire bonding process, the indexer moves each lead frame relative to a bonding head element of the wire bonder.

In conventional wire bonding equipment, the material handling system typically includes at least one magazine handler which holds a stack of lead frames. Lead frames move sequentially from the magazine handler to the bonding station along a support structure including, for example, a pair of rails. The wire bonding process is performed with the lead frame positioned at the bonding station. Following completion of the wire bonding process, the lead frame may be returned to the magazine handler.

Typically, each lead frame is pre-heated prior to the wire bonding process. The preheat process is typically performed with a pre-heat block positioned intermediate the magazine handler and the bonding station. The lead frame is brought into contact with the pre-heat block, and is heated to a temperature of, for example, approximately 160 degrees C. (320 degrees F.). For example, the pre-heat process may take approximately 15 seconds to complete.

In a conventional wire bonder having a single magazine handler, the pre-heat and wire bonding operations are typically performed sequentially, and thus the total processing time for a single lead frame includes both the time for the pre-heat operation and the time for the wire bonding process (which, depending on the number of connections to be formed and the speed of the wire bonding equipment, can vary, for example, over the range of about 37 seconds to about 120 seconds). If it were possible to perform all or part of the pre-heat operation on a first lead frame while simultaneously a second lead frame undergoes the bonding operation, it would be possible to increase the total number of lead frames processed by the wire bonder in a given period of time. However, in conventional wire bonders having a single magazine handler, the return path from the bonding station to the magazine handler (along which the pre-heat block is positioned) is desirably kept clear to allow a lead frame which has completed the wire bonding process to move from the bonding station to the magazine handler without the obstruction of a second lead frame undergoing the pre-heat process. Thus, the pre-heating and wire bonding processes are performed sequentially. It is known to provide two magazine holders with the wire bonder, allowing a first lead frame from the first wire bonder to be pre-heated, while a previously pre-heated second lead frame undergoes the wire bonding process. It would be desirable, however, to provide the improved processing times associated with two magazine holders without incurring the additional cost of a second magazine holder.

BRIEF SUMMARY OF THE INVENTION

According to an exemplary embodiment of the present invention, a wire bonding machine is provided. The wire bonding machine includes (1) a support structure for supporting a work piece, and (2) a pre-heat structure for supporting the work piece during a pre-heat operation. The pre-heat structure is moveable with respect to the support structure.

According to another exemplary embodiment of the present invention, a wire bonding machine is provided. The wire bonding machine includes (1) a magazine handler, (2) a bonding station for wire bonding work pieces, and (3) a material handling system for supplying the work pieces from the magazine handler to the bonding station. The material handling system includes (1) a support structure for supporting a work piece, and (2) a pre-heat structure for supporting a work piece during a pre-heat operation. The pre-heat structure is moveable with respect to the support structure

DETAILED DESCRIPTION OF THE DRAWINGS

According to certain exemplary embodiments of the present invention, a bypass system is provided which simultaneously allows (1) a first work piece to be wire bonded, and (2) a second work piece to be pre-heated. Further, according to certain exemplary embodiments of the present invention, (1) the first work piece (after wire bonding is complete) may be returned to a storage system (e.g., a magazine handler) while (2) the second work piece remains on a pre-heat structure.

Referring to the drawings, where like numerals identify like elements, there is illustrated inFIG. 1a portion of a wire bonding apparatus, generally designated by the reference numeral10. The portion of wire bonding apparatus10includes bonding station20having indexer22and material handling system30adapted to supply work pieces to bonding station20where the wire bonding operation is performed and to remove the work pieces from bonding station20following the wire bonding operation. For example, the work pieces may be lead frames90, although any other type of work piece is contemplated. Bonding station20and lead frames90are conventional.

Material handling system30includes a conventional work piece holder (e.g., a magazine handler32such as that incorporated into the Maxμm™ automatic wire bonder available from Kulicke and Soffa Industries, Inc. of Willow Grove, Pa.). Material handling system30further includes conveyor assembly40to transport lead frames90between magazine handler32and bonding station20. For example, gripper12is provided to move lead frames90along material handling system30to bonding station20. Conveyor assembly40includes support structure42functioning to support lead frames90during their movement. For example, support structure42includes first and second rails44and46(seeFIG. 2B). Support structure42includes first, second and third sections,48,50and52, respectively. First section48is at a first end of support structure42adjacent magazine handler32. Third section52is at a second end of support structure42adjacent bonding station20. Second section50is intermediate first and third sections48and52.

Bypass station60is provided as part of conveyor assembly40. Bypass station60is located within second section50of support structure42, that is, intermediate magazine handler32and bonding station20. Bypass station60includes movable pre-heat block62. Pre-heat block62is, for example, a resistive heater capable of heating lead frame90from room temperature to a fully pre-heated temperature (e.g., approximately 160 deg C. (320 deg F.)) in a time period of, for example, approximately 15 seconds. Pre-heat block62has first face64upon which lead frame90may be positioned in a pre-heating position. With lead frame90positioned on first face64in the pre-heating position shown (see lead frame90ainFIG. 2D), heat may be readily transferred from pre-heat block62to lead frame90.

Referring now toFIG. 2A, bypass station60including pre-heat block62is illustrated in a first position (a “down” position adjacent rails44and46). In this first position, in the illustrated exemplary embodiment, tabs/ears62aand62bare received by apertures44aand44cdefined by rail44. Rail44also defines aperture44bwhich is not used in the illustrated embodiment, but which may also receive another tab/ear of pre-heat block62in the first position.

Referring now toFIG. 2B, exemplary lead frame90is shown traveling toward (or away) from pre-heat block62of bypass station60. Pre-heat block62includes first edge66and second edge68. Pre-heat block62is sized, and the edges66,68are configured such that pre-heat block62is movable relative to first and second rails44,46between (a) a first position adjacent first and second rails44,46as shown inFIGS. 2A,2B, and2D, and (b) a second position raised above first and second rails44,46as shown inFIGS. 2C and 3. In the first position, pre-heat block62is nested within the rails44,46such that lead frame90can travel from first section48of support structure42into the second section, moving lead frame90into the pre-heating position. Similarly, in the first position, lead frame90can move from the pre-heating position away from second section50and pre-heat block62onto third section52of support structure42.

Pre-heat block62is moved between the first and second positions, for example, by linear actuator assembly76(seeFIG. 2B) which translates pre-heat block62vertically. Linear actuator assembly76includes lead screw78operatively coupled to motor80. Sliding support assembly82is connected to pre-heat block62and to a remainder of wire bonding apparatus10and operates to support and maintain alignment of pre-heat block62during movement between the first and second positions. It will be recognized that other conventional types of positioning systems (e.g., air cylinder systems, pneumatic cylinder systems, hydraulic cylinder systems, belt driven systems, etc.) could be substituted for lead screw78and motor80.

Referring now toFIG. 2C, pre-heat block62is illustrated in the second position (an “up” position above rails44and46). In this second position, in the illustrated exemplary embodiment, tabs/ears62aand62bare removed from apertures44aand44cdefined by rail44.

Referring now toFIG. 2D, pre-heat block62is illustrated in the first position with an exemplary lead frame90(i.e., lead frame90a) positioned thereon. While any type of work piece is contemplated, exemplary lead frame90aincludes five (5) semiconductor die90a1,90a2,90a3,90a4, and90a5.

With reference toFIG. 3, in the second position, pre-heat block62is moved away from support structure42to allow already wirebonded lead frame90bto move from bonding station20to magazine handler32(shown inFIG. 1), bypassing pre-heat block62. Thus, first lead frame90acan be undergoing the pre-heat operation with pre-heat block62in the second position, while simultaneously second lead frame90b(e.g., which has completed the wire bonding operation) can move from bonding station20back to magazine handler32.

According to an exemplary operation, with pre-heat block62in the first position, first lead frame90awhich is to undergo the wire bonding operation moves from magazine handler32, over support structure first section48to support structure second section50into the pre-heating station. Pre-heat block62is then translated upward into its second position, and first lead frame90aundergoes the pre-heat operation. While pre-heat block62is in the second position, second lead frame90bwhich has previously undergone the pre-heat operation and which has also completed the wire bonding operation moves from bonding station20across the third section52, through the second section50(and under pre-heat block62), and then through first section48as it returns to magazine handler32. With second lead frame90bclear of second section50, pre-heat block62is moved (e.g., lowered) from the second position to the first position. First lead frame90, now fully pre-heated, is then translated away from pre-heat block62and second section50, across third section52of support structure42and into position at bonding station20for the wire bonding operation. Simultaneously with movement of first lead frame90ainto bonding station20, a third lead frame90(not shown) may be moved from magazine handler32, across first section48and into the pre-heating station at second section50. Thus, the wire bonding operation and the pre-heat operations may be carried out at least, in part, simultaneously, rather than sequentially as is the case for a conventional wire bonder having a single magazine handler. Thus, a significant amount of time is saved in comparison to conventional techniques.

Therefore, a novel wire bonder apparatus and associated wire bonding process are thus described which provide improved processing efficiency for a wire bonder equipped with, for example, a single magazine holder.

Although the present invention has been illustrated and described primarily with respect to a single bond head wire bonding machine, it is contemplated that the teachings disclosed herein may be applied a multi-bond head machine (e.g., a dual bond head wire bonding machine). In such a configuration, for example, each bond head may be configured with a bypass station (and its own magazine handler) such as those described herein.

Although the present invention has been illustrated and described primarily with respect to a moveable pre-heat structure (e.g., pre-heat block62) which moves vertically away from a support structure, it is not limited thereto. For example, in certain configurations, it is contemplated that alternative motions may be utilized such as (1) lowering the pre-heat structure away from the support structure, (2) moving the pre-heat structure to a side of the support structure, (3) moving the pre-heat structure up and then to a side of the support structure, as well as many other potential motion paths.

Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions may be made therein and thereto, without parting from the spirit and scope of the present invention.