Total Pitch Tolerance

Accumulated Dimension Tolerance

The structure of a flat panel display (FPD) consists of a COF with driver ICs (source driver and gate driver) mounted at the edge of the panel.

To connect the COF to the glass panel terminals (Indium Tin oxide: ITO), an Anisotropic Conductive Film (ACF) is used.

Conductive particles within the ACF are dispersed when inserting between the connecting terminals(pads), and creates a conductive current path when the outer coating of the particle breaks open.

Upon bonding of the output terminals, if the accumulated dimension of the bonding area is out of specification, they will be misaligned with the terminals, resulting in poor connections or connection failures that connect to the wrong terminals, which would require repair work such as removal and re-bonding process.

Therefore, a COF with a small variation in the accumulated dimensions of output terminals is required.

Accumulated Dimension Tolerance COF Process outline Comparison COF Process outline Comparison

① FLEXCEED COF without Support Film (Support Film-less)

Better and stable OLTTP ( OL Total Pitch Tolerance : 0.01%)

⇒ Good OLB results

② Competitors' COF with Support Film;

Thermal history and tension effect wider variations of OLTTP


⇒ In case out of spec3% failure, theoretical OLB Yield loss is approx. USD3~5M (based on customers' input)