Chip on Chip (CoC) is a packaging technology designed to electrically connect two (or more) dice together, without the need for TSV (Through Silicon Vias). Electrical interconnection is achieved via fine flip-chip interconnects, sub 100 μm, in a face to face configuration. The mother die can then be connected to the package using flip-chip bumps or wire bonds, typically at a coarser pitch to match the package. The two (or more) dice can now communicate more efficiently at faster speeds, with larger frequency bandwidth, reduced electrical resistance (R), inductance (L) and capacitive resistances, and at a lower cost than TSV.

In the wire bond package interconnect scheme, the CoC is connected to the package substrate via perimeter wire bonds on the mother die.

POSSUM CoC Cross Sections

Conceptual Illustration of CoC Attached to Package Substrate Using Wire Bonds

The CoC may also be connected to the package via POSSUM™ configuration. In this configuration, the mother die uses fine flip-chip interconnects, sub 100 μm, and coarser pitch bumps to interconnect to the package substrate. The daughter dice is thinned to allow for Underfill clearance during package assembly. An added benefit of the POSSUM™ configuration is the reduced Z height of the CoC and overall package.

Amkor has taken a proactive but strategic approach in the research and development of CoC. The technology has been proven to be beneficial and advantageous from both a cost and technical standpoint. The CoC packaging method has evolved from the existing technologies of flip-chip and Fine Pitch Copper Pillar (FPCP), both of which Amkor has years of experience in mass production. Also, Amkor’s CoC technology uses existing infrastructure that is readily available, with minimum supplemental capital investment.

Complementary to CoC, Chip on Wafer (CoW) has now been developed and started production at Amkor. In the CoW approach the mother wafer is not sawn. Rather it is used as the substrate populated with sawn daughter dice. Besides all the advantages of CoC, the CoW provides the added benefit of chip set test and it simplifies logistics. Both 200 and 300 mm are supported with a wide range of die sizes and chip stack thicknesses.

This technology has been developed over the course of several years, in parallel with engaging key alpha customers for strategic market segments. This has allowed Amkor to support a wide range of products with a vast variety of application areas in the micro sensors, automotive microcontroller, wireless, optoelectronics and mobile arena.


X section of High End FCBGA Lidded Package using CoC POSSUM™ interconnect.


For more information on our Chip-on-Chip (CoC) POSSUM™ Packaging Technology, please contact an Amkor Regional Sales Office near you or fill out the Request for Information Form.


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