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Copper Wire Bonding

Copper wire bonding refers to the wire bonding process that employs copper wires for interconnection, instead of the gold and aluminum wires traditionally used in semiconductor packaging.

Copper is rapidly gaining a foothold as an interconnection material in semiconductor packaging because of its obvious advantages over gold, which include:
1) Cost reduction of up to 90%
2) Superior electrical and thermal conductivity
3) Less intermetallic growths
4) Greater reliability of the bond at higher operating temperatures
5) Higher mechanical stability.

Copper is inherently 3 to 10 times cheaper than gold, so substituting gold wires with copper wires can realize tremendous annual cost savings for a semiconductor packaging company.

Copper also has about 25% higher thermal conductivity than gold and copper wires dissipate heat within the package faster and more efficiently than gold wire, minimizing the thermal stress to which they are exposed.

Another advantage of copper over gold is its reduced tendency to form intermetallic compounds with aluminum bond pads. The atoms of the gold wire have a greater affinity to interdiffuse with those of the aluminum bond pad and form intermetallic compounds (IMC) with them. These IMC’s can create voids at the bond interfaces. The presence of such voids weaken the bond and can lead to bond lifting as well as other wire bond reliability problems. Other issues with IMC’s include stress, cracking and increased heat formation at the joint area problems. Copper wire can achieve greater mechanical stability than gold wire.

The disadvantages of copper wires versus gold wires include:
1) Copper tends to undergo oxidation at relatively lower temperatures
2) The hardness of copper wire require a bonding parameter (bond force and ultrasonic energy in particular) optimization to achieve effective bonding without causing cratering
3) Copper wire introduces a few failure analysis difficulties
4) Being relatively new, copper wire bonding technology is not yet as well-understood as gold ball bonding technology.

The oxidation of copper wire may be addressed by conducting the free air ball formation in an inert atmosphere. However, such a bonding process modification introduces new complexities into the assembly operation, such as parameter optimization for the nitrogen or forming gas used.

In summary, copper wire bonding offer many advantages over gold and aluminum wire bonding. However, it also comes with certain technological challenges that need to be overcome. The achievement of reliable fine-pitched copper wire bonds requires the formation of consistently round and reproducible free-air balls. This necessitates the prevention of oxidation in free-air balls, which can be attained by creating an inert atmosphere around it during electronic flame-off. Optimized bond parameters and well-designed bonding capillaries are also needed for reliable copper bonds.

Other Applications

Contact Information

Product NameDescription/BenefitsDownloads
Gases

Argon

Argon can be used as an inerting atmosphere in place of nitrogen for specialized processes.

Argon can be used as an inerting atmosphere in place of nitrogen for specialized processes.

Hydrogen

Hydrogen is a reactive gas that is used to reduce the metal oxides in your process.

Hydrogen is a reactive gas that is used to reduce the metal oxides in your process.

Nitrogen

Nitrogen can help you increase the number of first pass yields, reduce labor for rework and increase production rates. Gas atmospheres ranging from nitrogen to nitrogen-based blends can help improve productivity.

Nitrogen can help you increase the number of first pass yields, reduce labor for rework and increase production rates. Gas atmospheres ranging from nitrogen to nitrogen-based blends can help improve productivity.

Gas Blending Equipment

To accurately and safely blend gases to produce the proper percentages and flow rate of the process gas to the point-of-use.

To accurately and safely blend gases to produce the proper percentages and flow rate of the process gas to the point-of-use.

Optimization Studies

We align with your engineering team so we can understand your processes. By implementing our technology and process audits, we can assist you to use the process gases in a more efficient manner. It can improve the quality of your products being assembled and lower your cost of ownership.

We align with your engineering team so we can understand your processes. By implementing our technology and process audits, we can assist you to use the process gases in a more efficient manner. It can improve the quality of your products being assembled and lower your cost of ownership.

Process Audit

Our application engineers evaluate your inert atmosphere processing. Utilizing a temporary nitrogen supply system to your reflow furnace, they can help you improve solder joints, good wetting appearance and reduce oxidation of component leads.

Our application engineers evaluate your inert atmosphere processing. Utilizing a temporary nitrogen supply system to your reflow furnace, they can help you improve solder joints, good wetting appearance and reduce oxidation of component leads.

Safety Audits

Site visit to inspect the use of process gases and to assess their proper use from an EH&S viewpoint. To provide safety suggestions to reduce risks in the process areas and supply systems.

Site visit to inspect the use of process gases and to assess their proper use from an EH&S viewpoint. To provide safety suggestions to reduce risks in the process areas and supply systems.

Safety Training

Safety is our top priority. Our experts can train your personnel in the safe handling and use of industrial gases such as hydrogen, nitrogen, and oxygen.

Safety is our top priority. Our experts can train your personnel in the safe handling and use of industrial gases such as hydrogen, nitrogen, and oxygen.

Technology Audit

Our application engineers conduct an investigation at your facility utilizing our NitroFAS™ technology to introduce nitrogen into the solder process. Benefits can include defect reduction, reduced dross formation and solder oxide.

Our application engineers conduct an investigation at your facility utilizing our NitroFAS™ technology to introduce nitrogen into the solder process. Benefits can include defect reduction, reduced dross formation and solder oxide.

Test Program

To evaluate the use of our atmospheres to determine the benefits to your processes.

To evaluate the use of our atmospheres to determine the benefits to your processes.

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