YIELD Engineering Systems Inc.

Polyimides are high temperature engineering polymers utilized by semiconductor manufacturers for their excellent mechanical, thermal, and electrical properties.

Polyimides are usually applied in liquid form and then thermally cured as a thin film or layer to achieve the desired properties. Typically, polyimides are cured in a vacuum oven so effluents can be removed.

Precise temperature uniformity is essential in order to avoid cracks in the polyimide layer and color variations. Color uniformity is important for the pattern recognition systems used in assembly, and low oxygen values during this process help to achieve bright material and good adhesion.

Non-photosensitive polyimide is less expensive and easy to handle. By-products that occur during thermal curing are liquid, so they do not quickly form hard coatings.

Photosensitive material achieves better process performance, including higher resolutions, wider margins in photolithography steps, and longer shelf lives. By using photosensitive polyimide, the number of process steps can be significantly reduced. Ester bond types are more stable than ionic types and have the longest shelf life. Solubility of unexposed areas is also better with ester type polyimide.

For a system specifically suited to curing polyimides, visit the YES-450PB Series product pages.