SMTA International Conference Proceedings


FLIP CHIP ULTRASONIC GOLD TO GOLD INTERCONNECT FOR SMALL DIE WITH HIGH BUMP COUNT

Author: Philip Couts
Company: TDK Corporation of America
Date Published: 9/25/2005   Conference: SMTA International


Abstract: Flip Chip ultrasonic gold to gold interconnect (GGI) has provided a lead free, no clean, process solution for devices with bump counts under thirty for the past five years. The proven reliability and manufacturing cost savings of ultrasonic GGI bonding has now expanded to include large die sized up to 10mm2 with bump counts up to one hundred. The mounting accuracy of the GGI process is +/- 10 µm. The availability of a voice coil motor with 100N load capability and improved ultrasonic control has allowed for the performance improvement in ultrasonic GGI bonder equipment for fine pitch high bump die bonding. Improved devices using GGI CSP packaging such as sensor, RF, memory, and HB LED can now use the 100N ultrasonic GGI process.

Ultrasonic GGI bonders use a built in monitoring function for each die bond. Collapse height and impedance can be "mapped" for each die bond location in real time. Using the built in process each die location characteristics can be mapped. The map data is stored as a monitor text log file for easy access by other windows based programs.

Gold bonds provide superior bond strength because of the monolithic structure of the gold material. Gold bonds also have superior high frequency performance and low resistance when compared to solder or conductive materials. Die size reductions are achieved with flip chip ultrasonic GGI process when compared to wire bonding. The GGI ultrasonic GGI process reliably handles gold bump pitches of 100 µm or less in high volume manufacturing. This process capability has allowed die size reductions up to 70% when compared to wire bonding or C4 solder flip chip process.

Flip Chip ultrasonic GGI process can bond die with thickness as thin as 100 µm. This has been an important benefit for mobile products where low profile is critical. Low cost organic substrate materials and embedded passive LTCC substrates are used in flip chip ultrasonic GGI device manufacturing. Because the GGI ultrasonic GGI process relies on solid phase welding of the die to the substrate, relatively low bonding temperatures <150° C is used allowing it to be an excellent choice for substrate materials sensitive to heat.



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