Laser-Based Process Yields 3-D Circuitry on Molded Plastic Parts

Applying a circuit pattern directly onto a molded plastic component can eliminate the need for separate PCBs or circuitry, consequently reducing assembly time and associated costs for medical device development. It can also facilitate part miniaturization. Common methods for manufacturing these 3-D molded interconnect devices (MIDs), including two-component molding and hot-stamping, can be costly and require custom tooling, however. Emerging as a flexible and cost-effective potential alternative to these processes is laser direct structuring (LDS).

As the only contract provider of LDS 3-D MID services in North America, SelectConnect Technologies (Palatine, IL) is touting the technology's ability to achieve extremely fine, very thin line spaces in order to create a circuit pattern directly onto a plastic part. To do so, a part is first fabricated from an organometallic-infused plastic resin using single-shot injection molding. A range of materials are suitable for LDS processing, including LCP, PC, PBT, ABS, and PC-ABS, among others. Next, the molded part undergoes laser etching, during which the circuit layout is patterned onto the component.

"The part is then plated with electroless copper, nickel, and gold, and the metal is only deposited on the plastic where the laser has traced," explains Doug Gries, vice president of business development. Essentially, the laser activates the patterned surface, making it receptive to metallization and, subsequently, conductive.

"This is a technology that was developed in Germany and has just started to emerge," Gries says. "Five years ago, there were only about two applications that used this technology; now, there are about 25--and the list is growing." Medical applications for LDS range from hearing-aid components to glucose meters to switch rings for diagnostic pens.

To learn about SelectConnect's double-shot technology, which relies on double-shot molding and selective plating, read a case study featured in the Engineering Solutions section of the April issue of MPMN.