Organic chip carriers are built with resin based materials such as BT, IBM Driclad™ or FR4 with copper conductors.
The BT and Driclad carriers evolved from printed wiring board technology and utilize plated through hole vias for their layer to layer connections. FR4 is used in an IBM developed technology called Surface
Laminar Circuit™.
Surface Laminar Circuit builds on the standard printed wiring board to provide a high-density surface layer. This density is achieved by substituting micro vias for the plated through-hole vias with
a resulting two- to three-times reduction in land diameter. The Surface Laminar Circuit process also eliminates the surface layer of copper foil (used in standard printed wiring boards) and, with a lower
total external copper thickness, finer lines and spaces can be circuitized. Organic chip carriers can achieve pin outs exceeding 1,000 I/O. Chips are attached by fine gold wires with bond pad pitch spacings
as low as 60 microns or less or by flip chip.
