The present invention relates to a method for aligning a pair of planar templates on opposite sides of a planar board, and apparatus for practicing this method.
Double-sided circuit boards having aligned circuit patterns on opposite board sides are commonly used in the electronics industry. In the usual case, such a board is formed by placing circuit pattern layouts at mutually aligned positions on opposite sides of the board. A photo-etching process is used to remove copper selectively from plating on the two board sides, so as to leave the desired circuit pattern on opposite sides of the board.
The present invention contemplates a method and apparatus for aligning a pair of templates on opposite sides of a board. The method of the present invention includes cradling a board and a template placed against one side thereof, with such cradling producing alignment in the template and the board. Where the templates and board have matching, intersecting edges, the template and board are supported, in their cradled position, at such edges. The aligned board and template are flipped to expose the board's other side. The second template is placed against the exposed side of the board, and the two templates and board are cradled, again to produce alignment between the board and the second-mentioned template.
The apparatus of the invention includes structure defining a pair of surfaces, each surface being adapted to promote alignment between a board and a template placed against one side of the board. The surfaces are mounted for shifting toward and away from a position wherein a board and template placed against one are flipped onto the other to expose the other side of the board.
A preferred embodiment of the invention includes an open-book structure having a pair of interior surfaces which intersect along an inclined edge having raised and lowered ends. The structure pivots about an axis substantially paralleling this edge. Projecting from each of the surfaces in the structure, adjacent the lower end of the inclined edge, is a pin which cooperates with the two surfaces to promote alignment of a board and template placed against one of the surfaces.
A general object of the present invention is to provide a simple, efficient method for aligning a pair of substantially planar templates on opposite sides of a planar board, and apparatus for practicing the method.
A more specific object of the invention is to provide such a method wherein alignment between a board and a template placed against one side of the board is produced by cradling the board and template.