Plated Through-holes in Flexible Circuits
Figure 4: Carbon deposited on dielectric.The Shadow process ultimately leaves conductive carbon only where it is needed. The carbon-coated through-hole can now be electroplated as shown below:
Figure 5: Electroplated copper over carbon.
It is important to note that both the Shadow and electroless processes are only used to create the conductive bridge. Neither coating is robust enough to withstand environmental stress or conductive enough to carry significant current.
The Shadow Process vs. Electroless Copper
Some flexible circuit manufacturers are primarily using electroless copper and some are using conductive carbon. Each process has its benefits and drawbacks.
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