When you selectively metallize circuitry on plastic, you create what is called a 3 Dimensional Molded Interconnect Device or 3D MID. 3D Molded Interconnect Devices consist of circuit traces embedded onto molded thermoplastics to form electrical pathways and landings for surface mount components.
3D MIDs combine electrical and mechanical functionality. Electronic circuit traces are formed on the molding which can also be used as a housing, a chassis for additional electro-mechanical functions and the frame work for mounting chips, resistors and electronic connections.
Compared to 2-dimensional printed circuit boards or a flexible circuit, a 3D MID can take the shape of a molded component allowing circuit paths to be created on non-conductors used for the enclosure, chassis, and device structure. The electrical path is patterned in true 3D following the contour of the molded component.
The aim of these Molded Interconnected Devices is to achieve design freedom. 3D MIDs are designed to maximize the use of space where components are placed at different heights and in different declinations enabling an increase in functional density of products. Most importantly, utilization of a 3D MID in a design can lead to miniaturization, component reduction, a more environmentally friendly product and lower costs.
Designing systems with 3D MID components allows designers to reduce the size, weight, number of components and complexity, as well as to decrease assembly times and cost by having fewer components, wires and interconnects to assemble.
Two processes are commonly used to manufacture a 3D MID, the two-shot molding process and Laser Direct Structuring (LDS). Both 2 shot molding and the Laser Direct Structuring process use an electroless plating process called the SelectConnect™ Process developed by Arlington Plating Company and MacDermid to metallize the circuit patterns, plating a layer of electroless copper, electroless nickel, and finally, an optional layer of immersion gold.
There are several methods of creating a 3D MID, however the benefits can be seen across technologies.
Benefits of 3D MID Technology
Today’s plastics are strong enough to replace aluminum in many applications and plastics weigh half as much. Add to that the elimination of a Printed Circuit Board when you structure your circuitry directly onto the plastic part and your weight savings are substantial.
The combination of electric and mechanical systems combine with the efficient use of all the available space in the carrier allow for substantial reductions in size.
Your circuit paths are run directly on the molded component eliminating wires and interconnects. The need for multi-layer Printed Circuit Boards is also drastically reduced.
Because the electrical and mechanical systems are integrated, assembly times can be greatly reduced.