Tapered Focus Module
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-16
Inline Projection Printers (IPPs) are used to place circuitry on substrates. This placement of circuit lines is accomplished by focussing on the actual substrate to receive the circuit lines. The substrate is exposed and the line/space widths are measured and, if within specification, it is assumed that the expose tool is in focus. The limitation of this method is that variations in the substrates can range as high as 4 mils while the depth of focus for some IPPs is less than 3 mils. The following describes a tapered module which is used to eliminate focus problems in the manufacture of circuit lines on a substrate. The method works as follows.