The Latest Technical Trend of Dry Film Photo Resist

摘要

This paper describes the performance of several types of the most advanced Dry Film photo Resist (DFR), for producing high-density package substrates and chip on films (COF).rn1) High resolution type DFR, which achieves very fine conductive patterns less than L/S=15/15um by semi-additive plating process, is discussed.rn2) High photosensitive type DFR is presented, which is used for Direct Imaging (DI) exposure systems expected to be applied to MPU package substrates. In the DI exposure systems, the irradiance of exposure lights affects the DFR resolution. Selecting a new initiation agents, which ras high absorbance at h-line (405nm) for higher photo reaction efficiency, accomplishes the resolution of L/S=15/15um with 25um DFR thickness. This type of DFR also has high resistance for plating by using suchmonomers that increase of photo-reactive groups inside. The current target is L/S=10/10um resolution at quite low exposure energy, 10mJ/cm~2.rn3) Ultra thin DFR below 5um for high density COF and TAB by subtractive method gives higher performance than conventional liquid photo resists. The DFR, which has demonstrated excellent 2um resolution and adhesion with 2um thickness on the experimental basis, extends the application field to near one micron scale, from the previous ten micron scale.rn4) Other grades, thick layer DFR (120um thickness) for electroplating wafer bump formation and DFR for sandblasting which achieves dry etching of wafers, ceramics and glasses, are also introduced in the paper.