The relentless drive toward smaller, faster, and more intelligent electronic devices has pushed printed circuit board (PCB) technology to its limits. Among the most advanced solutions available today is Any Layer HDI (High Density Interconnect) PCB. Unlike conventional HDI, which limits microvias to adjacent layers, Any Layer HDI allows stacked microvias to connect any two layers in the stack‑up – from top to bottom.
For Electronics Manufacturing Services (EMS) providers and PCB manufacturers, mastering Any Layer HDI is no longer optional. It is a strategic capability required to build flagship smartphones, wearables, medical implants, ADAS, and AI accelerators.
In this comprehensive guide, we will explore:
- What Any Layer HDI is and how it differs from standard HDI
- Key manufacturing challenges and solutions
- Leading global manufacturers of Any Layer HDI PCBs
- Why EMS partners must embrace this technology
What is Any Layer HDI PCB?
Traditional HDI PCBs typically use a “1+N+1” or “2+N+2” build‑up sequence, where microvias connect only adjacent layers or skip one layer. Any Layer HDI goes further: it uses copper‑filled stacked microvias that can interconnect any two layers in the stack‑up, regardless of their position.
📌 Key characteristic: Every layer is a build‑up layer, and microvias can be placed directly over one another, forming a continuous conductive path from the top layer to the bottom layer.
Any Layer HDI vs. Standard HDI
| Feature | Standard HDI (e.g., 1+N+1) | Any Layer HDI (e.g., 3+N+3) |
|---|---|---|
| Via types | Buried, blind, microvias | Stacked microvias on every layer |
| Maximum layers | Typically 8–12 | Up to 20+ layer |
| Line/space | 50/50 µm | 30/30 µm or even 25/25 µm |
| Typical applications | IoT, industrial control | Flagship smartphones, AI modules |
For EMS providers, choosing Any Layer HDI means accepting tighter process controls – but unlocking the ability to build ultra‑compact, high‑performance assemblies.
Manufacturing Challenges for Any Layer HDI
From a PCB manufacturing perspective, Any Layer HDI is one of the most difficult technologies to master. Key challenges include:
- Laser drilling registration: Stacked microvias require multiple laser drills on the exact same spot. Misregistration of even 15 µm can cause open circuits.
- Desmear and cleaning: Residual epoxy from prepreg layers must be completely removed; otherwise, copper plating will have voids.
- Uniform copper filling: Void‑free filling of microvias is essential. Pulse plating or proprietary additives are required.
- Layer‑to‑layer registration: Thin cores and multiple lamination cycles demand advanced optical alignment systems.
Leading PCB manufacturers overcome these challenges using direct imaging, automated optical inspection (AOI) after each build‑up step, and X‑ray inspection for stacked via integrity.
Global Any Layer HDI PCB Manufacturers
The ability to produce high‑quality Any Layer HDI PCBs is concentrated among specialized manufacturers worldwide. Below are notable companies from key regions:
🇺🇸 United States
- TTM Technologies – A major US-based PCB manufacturer with advanced HDI lines for aerospace, defense, and medical.
- Unimicron USA – The US arm of the Taiwanese giant, offering Any Layer HDI for automotive and industrial applications.
🇪🇺 Europe
- AT&S (Austria) – A European leader in HDI and substrate-like PCBs, supplying Any Layer HDI for mobile and automotive.
- Schweizer Electronic (Germany) – Specializes in high‑frequency and HDI PCBs, including Any Layer designs.
🇯🇵 Japan
- Ibiden – Known for ultra‑high density interconnect PCBs used in flagship smartphones and AI accelerators.
- Shinko Electric Industries – Provides Any Layer HDI for semiconductor packaging and high‑end consumer electronics.
🇰🇷 Korea
- LG Innotek – Manufactures Any Layer HDI for mobile devices, automotive, and communication modules.
- Daeduck Electronics – A key supplier of advanced HDI PCBs to global electronics brands.
🇹🇼 Taiwan
- Unimicron – The world’s largest PCB manufacturer by revenue; a leader in Any Layer HDI for smartphones and wearables.
- Compeq Manufacturing – Specializes in HDI and Any Layer HDI for mobile and networking applications.
- Zhen Ding Technology (Flexium) – Provides Any Layer HDI for flagship consumer electronics.
🇨🇳 China
- Shengyi Technology – One of the first global manufacturers to mass-produce 16-layer Any-layer HDI; possesses 8-layer 28-layer HDI and 100+ layer high-multilayer PCB capabilities for AI accelerators and servers .
- Avary Holding – A global PCB leader with mass-production capabilities for 3-8 steps HDI and 4-14 layer Any-layer HDI structures, serving flagship consumer electronics and AI servers .
- Shennan Circuits – PCB business includes Any Layer HDI process capabilities for mid-to-high-end products in communications, data centers, industrial control, and automotive electronics .
- Dongshan Precision (Multek) – Leveraging Multek’s heritage, the company masters both HDI and high-multilayer PCB technologies, positioning itself for high-end AI computing applications .
- AKM Meadville Electronics (Xiamen) – Offers high-volume, highly reliable Any-layer HDI rigid PCBs up to 18 layers, with fine-pitch BGA and high-speed material hybrid capabilities
💡 Note for EMS buyers: When selecting an Any Layer HDI supplier, audit their laser registration capability, copper filling quality, and reliability testing (thermal cycling, IST).
Why Any Layer HDI Matters for Electronics Manufacturing Services
EMS companies sit at the intersection of PCB fabrication and final product assembly. Here is how Any Layer HDI directly benefits EMS operations:
Extreme Miniaturisation
By replacing through‑hole vias with stacked microvias, board area is dramatically reduced. EMS providers can integrate more functions into smaller enclosures – critical for wearables and hearables.
Thermal Management
Copper‑filled stacked vias act as thermal conduits, directly transferring heat from top‑layer components to inner ground planes. This reduces hot spots and improves reliability.
Improved Signal Integrity
Shorter vertical interconnects lower parasitic capacitance and inductance. High‑speed signals (PCIe Gen 4, LPDDR5) suffer less reflection and crosstalk.
Higher Assembly Yields
Any Layer HDI boards are manufactured with very flat surfaces (via‑in‑pad and planarization), improving solder paste printing and placement accuracy for fine‑pitch BGAs and 01005 passives.
Real‑World Applications
Application
Why Any Layer HDI?
Flagship smartphones
Highest component density (e.g., iPhone main board with 12+ layers in 1.2 mm thickness)
ADAS (Advanced Driver‑Assistance Systems)
High‑speed camera and radar data routing
Medical endoscopes
Ultra‑small form factor with reliable interconnects
Smartwatches
Mixed rigid‑flex with dense HDI for sensors and battery management
AI accelerators
Ultra‑fine lines and stacked vias for high‑bandwidth memory interfaces
How to Choose an EMS Partner for Any Layer HDI Projects
Not all EMS providers are ready for this technology. Look for:
Experience with via‑in‑pad assembly (void‑controlled solder joints)
In‑house SMT lines capable of 0.3 mm pitch BGAs and 01005 components
X‑ray inspection systems to verify stacked microvias after reflow
DFM feedback specific to Any Layer HDI rules (annular rings, microvia aspect ratio)
Conclusion
Any Layer HDI PCB is no longer an experimental niche – it is the backbone of modern, high‑density electronics. For electronics manufacturing services, adopting this technology opens doors to flagship projects. For PCB manufacturers, it represents the pinnacle of fabrication capability.
As demand for thinner, faster, and more integrated devices grows, partnerships between PCB fabricators and EMS providers will determine market leadership. Whether you are designing a 5G smartphone, an implantable medical device, or an AI module, Any Layer HDI is your path to success.
Ready to explore Any Layer HDI for your next project? Contact our engineering team for a free DFM review.
