PTI Blog

Multipurpose Wire Bonding–Bumps, Wires, Combination Interconnects, & Operation Efficiency

Posted by Janine Powell on Tue, Apr 01, 2014 @ 02:16 PM

Today’s multipurpose wire bonding machines are required to deliver a combination of wires, bumps, and specialty interconnects for RF, automotive, and optical markets with odd-form factor parts. These market production requirements are generally lower volume with a higher mix of products compared to typical high-volume semiconductor packaging of memory and logic. These markets also require multipurpose wire bonders to accommodate large work area, deep access, and a complex mix of bond surfaces, wire shapes, and bumps. The number of components in a package can vary from one with a few wires up to hundreds of components with thousands of wires.  Programming methods, process development, traceability, and rework are different for customers using this class of bonder.

The following four primary cases highlight the range of applications that can be handled for odd-form factor packages and specific areas of focus to maximize productivity for these classes of products.

Case 1: Ball Bump Size and Shape Examples  

The multipurpose wire bonder can generate a variety of bump shapes and sizes. 

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The largest bump with 119µm mashed ball diameter (MBD) is nearly as tall with an untraditional shape. Ball in corner is still in use today for joining two perpendicular conductive surfaces together. The 80µm MBD is a more traditional shape of ball bump. 

Case 2: Ambient Wire Bonding to a 6” Tall Package

In this example, the part required ambient bonding because of heat sensitive components, plustool heated by capillary it was impractical to get heat from the part base up through the entire 6” of length. A tool heater wrapped around the capillary is used to create the extra activation energy for bonding. Dual pyrometers for conductive heater plate and convective radiant tool heater are available. In this case the tool heater was used since the part could tolerate heat.

Case 3: Batch Load Tray (Mechanical and Vacuum Clamping)  

In this case, a customer has a wide range of odd-form packages that they manually load/unload onto a wire bonder. The batch load system is used to improve throughput and efficiency. There are two classes of parts that require either mechanical or vacuum clamping. Vacuum clamping is used to minimize tooling complexity where possible. However, there are cases where mechanical clamping is required to hold the parts. In both cases, trays full of parts are manually manipulated with a detachable handle. The handle locks into position and isolates the operator from heat. Each tray type has a mating heated base that is mounted to the bonder heater stage. Switching from one part type to another is accomplished by changing the base plate and loading another program on the bonder. Tooling is designed to minimize change-over time by ensuring that no adjustments to the EFO wand are required.

Case 4: Complex High Part Count

Odd-form factor packages come in a variety of complexities, from simple one die packages to hundreds of die in a single package. Some of these complex packages also allow alternate parts with alternate wires to be included within a single program. The operator interface should support the following five distinct phases of a package:

1.         Program creation and process development

2.         Documentation and transfer to production

3.         Production runs

4.         Product rework

5.         Long term program maintenance

In Conclusion

The purpose here was to show the differences in packages and capabilities between semiconductor and odd-form factor part (hybrid) wire bonding machines. Odd-form factor wire bonders discussed here have larger work spaces and handle a wider range of part sizes. Multipurpose bonder machine programming and navigation interfaces require supporting packages with one to hundreds of die. Multipurpose bonders are typically more expensive and have lower throughput when compared to semiconductor package wire bonders. However, many odd-form packages simply cannot be bonded on semiconductor bonders.

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Daniel Evans
Senior Scientist
Palomar Technologies, Inc.