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52 The PCB Magazine • August 2017 ± 2.9 μm and cross-sectional area of 6.08 ± 0.51 × 10 -10 m 2 . For these dimensions, a pattern con- sisting of bulk copper would have a resistance of 10.7 ± 0.9 Ω. Resistance measurements using a multimeter for four of these patterns gave a value of 24.1 ± 0.6 Ω, about 2.25 times the val- ue expected for bulk copper in this geometry. A major advantage to having wires embed- ded in a dielectric material is the ability to fine- ly control the geometry of individual wires and the pitch between wires, thereby enabling a more predictable total copper volume for any given pattern. Figure 4 demonstrates wires hav- ing a very fine pitch and controllable depth. The lines are 1–4 passes using 3 μJ, 1 MHz, 500 mm/s on the company system. After one pass the trench is about 8 μm wide and 7 μm deep. The width increases somewhat upon subsequent passes, and the increase in depth saturates with the number of passes such that at the fourth pass the trench is 9.5 μm wide and 20 μm deep. The lines are separated by about 10 μm. Figure 4 also demonstrates plated through-holes of 133 and 87 μm diameter (at the laser entrance side) in 150 μm borosilicate glass. In both cases the sidewall angle is around 82°, such that at the exit the diameters are 85 μm and 41 μm, respec- tively. Through-holes have also been drilled in Figure 4: A−C) Fine pitch lines and variable via sizes. Trenches in the glass are made with 3 μJ, 1 MHz, 500 mm/s and 1−4 repeats of the pattern on the company system. A) Height measurements of the etched glass. B) Dark field optical microscope image of the wires. C) Cross-sections of the wires. D−F) Through-holes in 150 μm borosilicate glass with 150 and 100 μm top diameters. LASER PATTERNING AND METALLIZATION TO REDUCE PROCESS STEPS FOR PCB MANUFACTURING