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50 The PCB Magazine • August 2017 areas were measured at 10 different locations in the wire to obtain an average value, which is re- ported with ±1σ. The wires have a cross-section that is an isosceles triangle approximately 25 μm wide and 25-30 μm deep, with a measured cross-section of 3.53 ± 0.38 × 10 -10 m 2 . Four- point probe measurements employed a produc- tion DC power supply for both establishing cur- rents from 50-200 mA across the plated features and recording the voltage drop. The reported resistivity values are the average of four mea- surements carried out at different applied currents for each sample to gauge the error in the resistance measurements; standard devi- ations of the resistance were less than 1% of the average (Table 1). The calculated resistivity values were between 1−1.5x the bulk copper value of 1.68 × 10 -8 Ωm (at 20°C). Most of the error in the resistivity measurements arises from uncertainty in the wire's cross section. A second pattern was employed for resistivi- ty testing (Figure 3, D-E) that consisted of 5 mm lengths of wire separated by 100 μm with a total length of a 411.14 mm. The dimensions of the wire were measured at 10 different positions, yielding a width of 24.3 ± 2.2 μm, depth of 38.9 Table 1. Resistivity measurements of 10 mm and 5 mm wires embedded in glass. Figure 3: Resistivity measurements. A) Height measurement of the intersection of the laser-etched wire and pad. B) Optical microscope image of a plated wire and pad. C) Patterns with 5 and 10 mm long wires used for resistivity testing. D−E) Long wire pattern and detail under optical microscope after laser patterning. The pitch between the lines is 100 μm and the total length 411.14 mm. LASER PATTERNING AND METALLIZATION TO REDUCE PROCESS STEPS FOR PCB MANUFACTURING