Chip-on-Board, or COB, applications consist of die directly attached to its circuit board. COB assemblies improve package performance as a result of the shorter interconnection paths and are a preferred application by process engineers.
COB technology is actually 'direct chip attachment', or DCA. Direct Chip Attachment assemblies can be called different names depending on substrate material. For example chip-on-glass (COG), chip-on-flex (COF), among others.
The COB process often has 3 steps:
- Die attach
- Wire bonding
- Encapsulation of the die and wires
The flip chip process incorporated with COB enables successful attachment without using wire bonding - and does so by bumping the bond pads on the correct side (via flipping the chip) and directly attaching the chip. With Flip Chip on Board (FCOB), underfilling the chip is required to protect the chip's active surface from damage.
Palomar Technologies Solution
Palomar Technologies offers two automated equipment solutions for die attach:
- 6500 Die Bonder - 1.5 micron, ultra-high accuracy die bonder
- 3800 Die Bonder - high-accuracy, ultra-flexible die bonder
Both the 6500 Die Bonder and 3800 Die Bonder are designed for high-accuracy die attach, flexibility and factory automation. Chip on Board applications can be performed doing just direct chip attachment, or incorporation of a flipper for flip chip. These die bonder machines can also be retrofitted with conveyors and handlers, automatically feeding the package into a wire bonder.
Depending on application requirements, the three-step COB package can be successfully accomplished in a single run.