| 摘要 |
A contact printing system produces photopatterned planar workpieces, such as printed wiring boards, with polymerized patterns on photopolymer coatings of precisely controlled thicknesses from a few microns to at least 0.08mm., with the workpieces ready for development by washing out unpolymerized portions. Mesh screens deposit the initial polymer coatings, on the workpiece and preferably also on a phototool image bearing surface, so that two layers are merged into one. A clamshell fixture permits the layers of pastelike consistency liquid photopolymer to be sandwiched in precise registration for photoexposure from an U.V. lamp radiation source. An operator can prepare one workpiece as another is being photoexposed. A second exposure chamber permits preexposure of the layer on the phototool with one surface exposed to air to permit partial polymerization through its thickness, so that when merged onto the workpiece layer in liquid to liquid bubble free contact, wiring traces and through holes are covered with polymerized polymer of controlled thickness. Boards are photoexposed on both sides before development, low energy is used and operator controlled steps are provided to produce high speed production of up to 60 double sided workpieces per hour. |
