Fig. 1. Experimental setup for LIFT

Fig. 2. Fabrication of bulk structure by LIFT. (a) SEM image of single transfer particle array prepared on silicon sheet; (b)‒(d) schematics of preparing monolayer bulk structure by multiple transfers;(e)‒(g) SEM images of surface structures obtained at different stages of preparing monolayer bulk structures on silicon sheet; (h) schematic of staggered filling in z-direction; (i) optical microscope image of bulk structure prepared on epoxy resin plate, where inset at upper left corner is image taken during body resistance measurement process after probes are placed onto sample; (j) surface SEM image and (k) surface profile of prepared bulk structure; (l) section images of prepared bulk structure sample with original image at top and image after binarization at bottom

Fig. 3. Fabrication of bulk structure by LIFT combined with electroless plating on epoxy resin receptor. (a) Equally spaced particle array prepared by four LIFTs; (b) deposition of copper on surface of copper column array prepared by LIFT; (c) change of height of copper column array with forming times under different d; (d)(e) SEM images of copper column arrays with different spacings prepared by LIFT, in which Fig. 3(d) is top view and Fig. 3(e) is 45° side view; (f)(g) SEM images of surfaces after electroless plating, in which Fig. 3(f) is top view and Fig. 3(g) is 45° side view

Fig. 4. Effects of copper column spacing d on properties of structure after deposition. (a) Surface profiles and (b) roughness values of structures before and after electroless plating; (c) resistivity of structure after electroless plating; (d)(e) section images of structures after electroless plating, with original optical microscope image at top and black and white image obtained after binarization at bottom; (f) internal porosity of structure after electroless plating

Fig. 5. Comparison of properties of bulk structures prepared by LIFT and LIFT combined with electroless plating (LIFT+EP). (a)(b) SEM images of surfaces of two structures; (c) comparison of surface profile curves of two structures; (d)(e) EDS surface scan analysis results of two structures; (f) comparison of surface element compositions of two structures; (g)(h) SEM images of microscopic cross sections of two structures, in which the microscopic cross sections are obtained by FIB method

Fig. 6. Metal lines and 3D step structures prepared by LIFT combined with electroless plating method on epoxy resin plate. (a) SEM image, (b) 3D profile, and (c) surface contour curve at black dotted line shown in Fig. 6(b) of metal lines; (d) SEM image, (e) 3D profile, and (f) surface contour curve at black dotted line shown in Fig. 6(e) of 3D step structure