TECHNICAL GUIDES
HDI Design Handbook: Any-Layer vs 2+N+2
Fabrication · Technical Guide
Any-Layer vs 2+N+2
Any-Layer
Maximum Density
Every layer carries signals; microvias stack anywhere — the highest escape density available.
A
B
2+N+2
Cost-Efficient
A conventional core routes the bulk of signals, with two build-up layers per side on top.
Routing on every layer, with stacked laser vias in any layer pair.
Density
Core routes most signals; escape limited to 2 build-up layers per side.
Microvias stacked anywhere in the stack-up, no position limit.
Via Stacking
Stacking limited to outer build-up pairs around the core.
Via-in-pad under the BGA body — no dog-bone fanout needed.
Via-in-Pad
Via-in-pad possible near the BGA periphery, rarely under the die.
Sweet spot: 0.3mm pitch and below.
µBGA ready
µBGA ready
BGA Pitch
Sweet spot: 0.4mm pitch and above.
Cost sweet spot
Cost sweet spot
Higher — repeated laser drill, plating and lamination cycles.
Process Cost
Lower — standard core drills and familiar lamination.
More inspection steps; longer lead time.
Yield & Time
Consistently higher first-pass yield, shorter lead time.
Flagship phones, AI modules, µBGA fanout, extreme routing density.
Best Fit
IoT, industrial control, cost-sensitive HDI, 0.4mm+ pitch BGA.
The Verdict
There is no "better" architecture — only the one that matches your pitch, your density, and your cost ceiling.
Choose Any-Layer when…
- BGA pitch is 0.4mm or tighter
- Vias must sit directly under the BGA body
- You need maximum escape density with fewer layers
- Density outweighs unit cost in your BOM
Choose 2+N+2 when…
- Your BGA pitch is 0.4mm or looser
- A hard cost ceiling drives the design
- High-volume first-pass yield is the priority
- You want the shortest possible lead time
<100µm
Typical laser via diameter in production
1:1
Recommended depth-to-diameter ceiling for stacked vias
3 mil
Minimum laser microvia we drill in volume
O-Leading Engineering Note
We build Any-Layer HDI up to 44 layers with copper- and resin-filled via-in-pad and full AOI + X-Ray verification. Send us your stack-up and a free DFM review will tell you which architecture clears your design at the lowest cost.
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