Chip on Board Assembly Process
Chip-on-board or chip-on-substrate assembly technology relies on widely available die attach and wire bond infrastructure to ensure highly reliable interconnection between the die and substrate.
COB provides the capability to perform direct chip to chip wiring that facilitates improved performance and strong functional integration in many modern high speed applications.
Courtesy of Portelligent, Inc., 1998 data
The COB Process
Bare die mounted on interconnecting substrate
Die are mechanically attached to the substrate using conductive or non-conductive epoxies
Die are electrically connected to the substrate using wirebonding
Die are encapsulated with a protective shell
-No major shift in proportion of SMT, Through Hole vs Price.
-COB constructions dominate at the low end and high end of the product set; COB appears in low cost throw-away assemblies and more expensive profile-critical products.
The Chip on Board structure is shown below in cross-section.
This photo shows a finished module.
Source: GJ Technology