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32 The PCB Magazine • September 2014 The most common methods for integrating electronic circuits directly on plastic compo- nents are: • Hot stamping, using a die to press thin flexible films onto a plastic component: Excess film is then removed. This method is simple and works with a large range of materials. The prob- lem is that this method is incapable of creat- ing fine tracks, real 3D structures, and complex circuits. A change of layout data also requires a new film or a new stamp tool. • The two-component injection molding method: This works by using the first metal- lizable polymer to mold a structure with the circuitry at the surface. The second polymer is not metallizable and covers those areas with- out conductive tracks. This method allows a great deal of 3D design freedom, but it needs high upfront costs and is restricted to only a few types of plastic. Two complex injection molding tools are required. Creating fine tracks is also a problem. Another negative aspect is the relatively long time needed to successfully push products of this kind through the product pipeline and onto the market. The lead time for the development of injection molding tools alone is around two months, but in very high series without layout changes this method is very economical. • The subtractive method: This method uses a laser to remove metal layers where they are no longer required, or to open a resist for the sub- sequent etching process. This method requires long laser exposures, and components with ful- ly metallized surfaces. • The Laser Direct Structuring method (LDS): Patented by LPKF, this method provides further advantages, both technically and economically. The LDS method uses a thermoplastic polymer doped with a laser-activatable metal-polymer additive. When the laser beam hits this poly- mer it activates the metal complex and creates a precise track with a rough surface. Exposed metal particles form the nuclei for the subse- quent metal coating process. The laser beam therefore draws the structures required on the component so that the conductor layers are cre- ated precisely along these tracks in a currentless metal coating bath. Copper, nickel and a gold finish can be successively applied. The LDS Process, Step-by-Step All the special strengths of lasers such as high flexibility, speed, resolution and precision, are utilized in this process. If the circuit has to 3D LDS COMPONENTS continues figure 1: differentiation of the use of lds systems by market segments (3d-mid e.V.).