High Speed Digital Imaging Using Gray Level with Micromirror Array

摘要

In recent years the PCB industry has increasingly turned to digital, or maskless, imaging techniques in order meet demands for tighter registration between layers. Many of these techniques, including laser direct imaging (LDI), rely on a "dot-matrix" style exposure technique that uses "binary" pixels and small pixel or dot spacing to achieve the required resolution. This results in limitations in write speed and throughput, since many small pixels or dots must be written over a relatively large area PCB substrate. A patented gray level technique1 based on a commercially available digital micro-mirror device (DMD) achieves required resolutions with a relatively large projected pixel size, and thus offers a higher speed alternative to conventional digital techniques. Gray level, or dose control as a function of panel position can also provide some degree of compensation for minor processing or development artifacts that are known to recur in the same areas of a panel.