More About PCM
The PCM process lends itself to intricate designs of low to medium volumes of metal parts which are thin and difficult to handle. "If it can be drawn, it can be etched," is considered the extent of the process' design capabilities. Most PCM applications employ flat metal stocks, but various 3-D shapes can be utilized to produce rather exotic parts.
Although the PCM process lends itself economically to middle range production runs, it is capable of prototype to large volume applications where the unique advantages of the PCM process reign. Because of the low initial tooling costs and fast tooling turnaround, PCM production is very appealing compared to stamping dies. Parts that are formed by the PCM process range from flat springs, electronic lead frames, medical implants, and pump valves to highly ornate decorations and ornaments.
Low tooling costs are only the beginning of the advantages of the PCM process. The photographic tool can be produced within days of receipt of a CAD drawing and production can begin as soon as the metal is coated and the tool is accepted. In addition, adjustment to the tool configuration or dimensions can be performed with minimal costs and delays. Therefore, critical time-to-market considerations are substantially reduced.
The photo tool lends itself to multiplicity of design whereas multiple pieces of the same design or different designs can be incorporated on the same sheet of metal. The same photo tool is used during the production process to provide precise reproduction of the pieces during production runs.
Since the PCM process "dissolves" the metal during formation edge burrs do not exist. Nor does it alter the edge characteristics, as is the case with laser cutting. Therefore, expensive de-burring processes are eliminated. Etching does dissolve the metal laterally as well as vertically, so an undercut of the mask or photo resist results. Since most PCM applications utilize etching from both sides of the metal surface, a slight metal "cusp" forms mid way down the cross-section of the metal part. This physical attribute is minimized by etching solution parameters and typically is not a major consideration.
Because the metal is dissolved during the PCM process, the original characteristics of the metal such as hardness, grain structure, magnetic properties and ductility are not changed during the process. The metal characteristics are the same from the beginning to end of the process.
When metal pieces are formed into shapes after the initial PCM process, form lines can be incorporated into the photo tool. The subsequent "half etch" areas are produced on one side of the metal and provide precise and easy forming into the final configuration.