Polymer Collar WLP™ Process Summary

Below is an example of Polymer Collar WLP on UltraCSP Bump on I/O. (None of the drawings are to scale)

Deposit and pattern a layer of BCB passivation.

Deposit three layer (Al/NiV/Cu) Under Bump Metalization (or UBM) stack.

Pattern UBM pads.

Deposit Polymer Collar Material

Attach pre-formed solder ball.

Reflow solder.