Ultrasonic welding can reduce bonding pressure and temperature and improve the bonding process, which is particularly beneficial in semiconductor manufacturing. For example, solderless die-to-die bonding technology in flip-chip bonding enables area array interconnections by using the process to join the array of gold bumps located at the bottom of an IC with gold-plated pads on a substrate. Thermocompression bonding (TSB) can be used especially for this uncomplicated, clean and dry assembly process.
The TSB process starts with a substrate placed on a heated support and held in position by vacuum. A pick & place tool holds the chip with a die collet designed for thermosonic bonding applications. The gold stud bumps are contacted with the substrate once the chip is aligned with the substrate by a pattern recognition system. Once the required adhesion force is achieved, the current of ultrasonic welding is applied for a defined period of time.
The vertical technology offered guarantees stable and accurate coplanarity and parallelism over the entire Z-axis stroke. In combination with the force control, an excellent joining result can be achieved at any height. Furthermore, it is possible to individually programme decisive parameters such as force, temperature and power of the ultrasonic welding as well as the process time.
The IP collet (inverted pyramid (IP)) is also of central importance. If access to the tool is limited, an additional channel type (CH) collet can be used in addition to the IP, which is usually used for undemanding tasks. Particularly if this is to be aligned on two sides of the chip. Whether a collet is suitable for the TSB can be determined by various factors. For example, the cyclic movement of the collet during the US process, the sensitive surface of the chip and the heat transfer.
US power and collets can be used to create an excellent bond between a chip and a substrate thanks to next generation thermosonic bonding. The pick & place system offering excellent coplanarity and parallelism along the Z-axis thus ensures accurately bonded chips.
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Firma: Tresky GmbH
Ihr Ansprechpartner: Daniel Schultze