Electroless plating is the method for forming electro-mechanical traces on the laser defined structures or the double-shot molded component. The metallization sequence is electroless copper plating (100 to 600 micro inches), electroless nickel plating (50 to 100 micro inches) and optional immersion gold plating (3 to 8 micro inches).
The first step in the process is depositing electroless copper on the laser defined pattern or the catalyzed double-shot material. In either case, deposition of the electroless copper in the desired areas is dependent on a catalytic contrast between plated and non-plated areas. In the case of double shot molding, the contrast is enhanced by adding palladium to the double-shot material creating an electronegative potential that initiates deposition.
The result of laser ablation on the Laser Direct Structured thermoplastic (organometallic doped) is a textured surface with exposed metal particles that produce an nucleation site for copper deposition.
Most Molded Interconnect Devices (MIDs) are then plated with electroless nickel providing a robust surface against oxidation. A topcoat of immersion gold may be applied to improve solderability and further guard against long term oxidation or for the gold layer can be built up using an electrolytic process for applications requiring a thicker layer of gold.