With Moulded Interconnect Device technology – MID for short – visible, three-dimensional conductive paths can be applied to the surface of injection-moulded components. This enables mechanical and electronic functions to be integrated on a single shaped part in a unique way.
The products can therefore be designed much more freely in terms of space and made much smaller and lighter – an important step towards further miniaturization. In addition, MID components often do not require any cables, which makes them much easier to mount. Unlike classic, primarily two-dimensional printed circuit boards, MID technology uses a three-dimensional shaped part as a circuit board, such as the housing for example. There are various ways to produce MIDs. In the case of the frequently used Laser Direct Structuring (LDS), a special metallic compound is added to the injection-moulding plastic. As a first step, this material is used to mould the required component.
The areas that need to have conductive paths are then exposed with a laser beam. The additive is activated and immersed in a copper bath during the subsequent metallization process, which shows up the conductive paths in a sharp outline. Various coatings, for example nickel, gold, silver or soldering tin, can be applied one after the other. Electric circuits can be soldered onto these conductive areas.
Photo credit: LPKF/LDS
The small-sized MID technology has already proven itself in many everyday applications. MIDs can for example be found in cars. A compact MID pressure sensor in the ESP brake control system converts the hydraulic braking pressure into an electrical signal. MIDs are also used in mobile telephones. The three-dimensional circuit boards on the plastic housing inside the mobile phone act as an integrated antenna. Applications can also be found in, among others, medical, air-conditioning and safety technology.
The making-of video (MID technology starting at 4:05 min.)