An Introduction to High Reliability Soldering and Circuit Board Repair by Ahlhelm N

Author:Ahlhelm, N [Ahlhelm, N]
Language: eng
Format: epub
Published: 2013-07-27T00:00:00+00:00

The Artwork

Computer-Aided Design (CAD) eases the development of PCB’s considerably. Not so long ago, designers would use templates and stencils to draw the circuits under design. Once the design was approved, the artwork would be photographed and a positive or negative

image made. Both images would be printed on a clear photographic sheet of acetate film. The white areas on the images would be clear on the acetate sheets. Figure 5-12 shows the original design; Figure 5-13 is the negative image. Both images can be used to make circuit boards. A board used with is the negative image. Both images can be used to make circuit boards. A board used with 12 would have the exposed resist (resist is covered in Photo-Developing on the following pages) softened and leave the tracks and pads in their original state. With Figure 5-13, the exposed resist would harden and all the unexposed areas would be removed.

Many programs are available to create circuit images. Some professional versions can cost several thousand dollars. A few design programs are available as freeware and are quite good. They can generate positive and negative images as well as Gerber files needed for milling the PCB (see Milling under Subtractive Methods). Stencils and templates are still available.

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