We are currently designing an 8-layer FR4 PCB (1.5 oz outer copper, 2.0 oz inner copper) using BGA Ultralow Noise Silent Switcher 3 µModules, specifically the LTM4732, LTM4703, and LTM4702. 4 inner layers are GND and power planes; prepreg thickness between TOP and inner plane is 4 mil
We are evaluating two thermal/layout VIA options:
- Via-in-Pad (8/18 mil): Resin-filled (epoxy) and capped (VIPPO).
- Dogbone / External Vias (16/28 mil): Placed between pads and connected via 16-mil trace short routes.
Could you please advise which option Analog Devices recommends for optimal thermal performance and reliable SMT assembly yield?