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72 PCB007 MAGAZINE I JUNE 2019 Article by Joan Tourné NEXTGIN TECHNOLOGY Micro-machining is used every day in circuit board manufacturing with both drill and rout- ing bits. Micro-machining is a very broad term for techniques used to shape an object. I in- troduce this term because micro-machining, in combination with the fabrication and process- ing of objects in 2.5D and 3D is not commonly used in circuit board manufacturing. But ver- tical conductive structure (VeCS) technology will change that. Today, the industry has available to it the in- frastructure needed to shape circuits in a dif- ferent way and to create new functions and ap- plications, such as higher density connections between internal and external layers and tuned connections that minimize signal distortion. VeCS is a multi-depth slot element currently achieved with CNC machines (part of today's infrastructure) using drill and router bits to create the shapes (Figure 1). The objective is to create a new structure that makes the verti- cal connections using the board real estate dif- ferently so that we do not comprise isolation. CAF/electron migration are the primary con- straints in reducing the distance between verti- cal connections (via hole, microvia, etc.). By using micro-machining, we can create struc- tures that are less–or not at all–sensitive to these isolation defects. VeCS-1, as described in the first article of this series, is a slot go- ing through the circuit from top to bottom. In this article, I will focus on VeCS-2 technology (blind slots) as more micro-machining tech- niques are required for VeCS-2 than VeCS-1. Note that the examples in this article all fo- cus on slots with the same depth. In a later Vertical Conductive Structures, Part 2: VeCS and Micro-machining Figure 1: The basic VeCS element shown from the bottom side using two traces and a power connection at the far end of the slot. Terms for the wide structures are cross route and bottom route.

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