06 — Route Analysis

Power Plane Observations

• Ground pour visible on bottom side (exposed areas show green soldermask over copper fill)
• Ground plane likely continuous across most board area — typical for EMI/thermal management
• Power planes estimated on inner layers (not visible) for VCORE, VMEM distribution

Signal Route Observations

• HDMI traces: run from SoC area (under main shield) to HDMI connector — cannot trace visually
  due to shields, but must pass through PCB layers beneath shield boundary
• USB power traces: Micro-USB VBUS → PMIC input (visible inductor L700 in this path)
  L700 + nearby capacitors form classic LC input filter for switching regulator
• Antenna feeds: PCB trace antennas originate at RF IC (BCM43569, under "TA" shield)
  and extend toward board edge near HDMI connector end — cannot see traces but antenna
  region is clear from shield placement and FCC test report

EMI Shield Grounding

• Three shields soldered to PCB ground at perimeter via castellated tabs
• "TA" shield (top, near HDMI): grounds RF section — critical for 5GHz antenna isolation
• Main SoC shield: large ground cage over highest-frequency digital section
• PMIC shield: smaller, isolates switching regulator noise from RF section

Layer Count Estimate

• Visible vias suggest at least 4 layers: top signal, ground, power, bottom signal
• High-density BGA routing (MT8127D) typically requires 4–6 layers
• Estimate: 4 layers (cost-optimized for consumer device at this price point)

Decoupling Cap Placement

• Multiple 0402 caps visible clustered near the boundary of the main SoC shield
  (bottom side) — these are bypass capacitors for the SoC's power rails
• Blue ceramic cap (likely 10µF or 100µF) visible — bulk capacitance near PMIC output

Authored: Albert Lane + Claude Sonnet 4.6 · SovereignAudits™ · 2026-06-10