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What is I/O bump and FLIP CHIP methadology

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Full Member level 3
Feb 28, 2007
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In SOC encounter's user guide, there is a section on flip chip methodology. I am finding it hard to understand:
1) What is bumps (I/O bumps) .
2) What is FLIP chip method?

Please explain bumps first, so that i can go through the section once again.


An IO bump is a large lump of solder placed on top of each of the bondpads at the end of processing an IC, The chip is then "flipped over" inside the package, the whole thing is heated up in order to melt the solder lumps, which are already in the correct locations for bonding to the package. This is basically Flip Chip Technology. The nice thing about this technology is that your bondpads can be located anywhere on your chip, they don't necessarily need to be at the chips edges.
See: "IC Mask Design: Essential Layout Technioques" Christopher and Judy Saint

Flip-chip is a method for interconnecting semiconductor devices, such as IC chips and Microelectromechanical systems (MEMS), to external circuitry with solder bumps that have been deposited onto the chip pads. The solder bumps are deposited on the chip pads on the top side of the wafer during the final wafer processing step. In order to mount the chip to external circuitry (e.g., a circuit board or another chip or wafer), it is flipped over so that its top side faces down, and aligned so that its pads align with matching pads on the external circuit, and then the solder is flowed to complete the interconnect. This is in contrast to wire bonding, in which the chip is mounted upright and wires are used to interconnect the chip pads to external circuitry.

It is well explained here with pictures.
Flip chip - Wikipedia, the free encyclopedia
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