Issue link: https://iconnect007.uberflip.com/i/1156271
96 PCB007 MAGAZINE I AUGUST 2019 Padstack Generation (1-mm BGA/0.045-mm Ball Pads) Plated Slots • Plated slot used as a base for the structure which does not directly connect to a net (Fig- ure 6) • Drill = 5.254 mm x 0.254 mm – X size slot = span of BGA pads connection + Y size slot • Regular pad (all layers) / mask pad (external layers) = oblong 5.508 mm x 0.508 mm • Anti-pad = oblong 5.127 mm x 0.127 mm – Anti-pad is smaller than drill to allow connection via attachment to slot hole wall on negative planes – Anti-pad on connection via and keepout in non-plated hole will isolate non-connected locations • Thermal pad (all layers) = none – Plated slot is not directly connected to a net, no thermal required • Adjacent layer keepout = oblong 5.508 mm x 0.508 mm – Mechanical drill overshoot clearance for VeCS-2 (blind depth) • Plated slot placement – Orthogonally placed between BGA ball pads (Figure 7) Non-Plated Hole/Slot (Slot Separator) • Non-plated hole is used to divide the slot into multiple sections so that individual connections can be made by traveling down the slot hole wall (Figure 8) • Drill = 0.559 mm • Regular pad (all layers) = circle 0.127 mm • Anti-pad/thermal pad (all layers) = none • Keepout (all layers) = circle 0.813 mm • Mask pad (external layers) = circle 0.356 mm • Adjacent layer keepout = circle 0.813 mm – Mechanical drill overshoot clearance for VeCS-2 (blind depth) • Non-plated hole placement – Spaced on 1-mm centers orthogonally placed between BGA ball pads aligned with plated slot (Figures 9 and 10) Connection Vias • Connection via adopts the BGA pad net name using the cline stub (Figure 11) – Cline width = 0.127 mm - 0.222 mm (outward) – Cline length = 0.162 mm (outward) – Cline stub is only required on the BGA pad layer • Drill = none • Regular pad (all layers) = rectangle 0.228 mm x 0.222 mm – Offset Y = 0.100 mm • Thermal pad (all layers) = circle 0.012 mm • Anti-pad (all layers) = rectangle 1.000 mm x 0.350 mm – Offset Y = 0.164 mm • Mask pad (all layers) = none Figure 6: Plated slot. Figure 7: Alignment in BGA pin field. Figure 10: Alignment in BGA pin field. Figure 9: Plated slot and non-plated hole (slot separator) alignment. Figure 8: Non-plated hole (slot separator).