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68 The PCB Magazine • September 2017 can be input into the generation of the print path of the object. This will squeeze the lines closer together, minimizing voids, to an extent. When a high overlap factor is specified, the ma- terial being squeezed together must go some- where and thus it is displaced upwards. This will create a rough surface finish if on the top layer, and could throw off overall height dimen- sions if allowed to compound throughout the print. When printed with the 0.4 mm nozzle, many, albeit smaller, voids are introduced into the object. While the few voids that are pres- ent with the spaghetti-printed layer are larger, the total void area of the parts printed with the 0.4 mm nozzle is greater. These voids contrib- ute to the ~10% difference in ultimate tensile strength for the printed specimens (Figure 9). The print direction plays a major role in the strength of printed parts [7,8] . It is common prac- tice when printing structural parts to have lay- ers printed in the direction of force that the fi- nal part will experience. To exemplify why printing in the direction of force is important, 3D PRINTED ELECTRONICS FOR PRINTED CIRCUIT STRUCTURES Figure 7: Cross-section view of printed layers with a 0.4 mm nozzle. Figure 8: Cross-section view of spaghetti-printed layers. Figure 9: UTS comparison of spaghetti and 0.4 mm nozzle tensile specimens. Figure 10: UTS of 0° and 90° tensile specimens.