High-Density Interconnect (HDI) PCB is a premium printed circuit board defined by IPC-2226 standards, featuring ultra-fine line geometries, microvia interconnections, and high wiring density. As the core interconnect solution for high-integration, miniaturized electronic systems, HDI PCB uses laser-drilled microvias (down to 50μm) and buried vias to achieve layer-to-layer signal interconnection, breaking the wiring limitations of traditional through-hole PCBs. It is the industry-preferred solution for high-end chipsets, high-speed signal transmission, and ultra-compact electronic designs.
HDI Structure & Tier Classification
In line with global PCB industry standards, HDI tiers are defined by the number of sequential lamination cycles for build-up layers, with standard structural nomenclature as n+N+n (n = number of build-up layers on each side of the core, N = number of core layers):
- 1st Order HDI (1+N+1): Single build-up layer on both sides of the core, with laser microvias connecting the outer layer to the adjacent inner layer, the most widely used mainstream HDI structure
- 2nd & Multi-Order HDI (2+N+2 to n+N+n): 2 or more sequential build-up layers, supporting staggered or stacked microvias to achieve cross-layer interconnection, for higher wiring density requirements
- Anylayer HDI: The highest-density HDI technology, enabling interconnection between any two adjacent layers through laser microvias, with no full-panel mechanical through vias. It maximizes wiring space and is the standard solution for flagship consumer electronics and high-end chip packaging substrates.
Core Manufacturing Technologies
Laser Microvia Fabrication Process
All processes below are based on industry-standard 17μm (1/2 oz) finished inner layer copper thickness, with strict compliance with IPC-6012 performance specifications:
- Staggered (Non-Stacked) Microvia Process
Inner Layer Pattern Transfer → Core Lamination → Brown Oxide Treatment → Laser Drilling → Desmear & Debrowning → Electroless Copper Deposition → Panel Electroplating & Microvia Filling → Cross-Section Validation → Outer Layer Pattern Transfer → Etching → AOI Inspection → Post-Fabrication Processes
- Stacked Microvia Process
Inner Layer Pattern Transfer → Core Lamination → Brown Oxide Treatment → Laser Drilling → Desmear & Debrowning → Electroless Copper Deposition → Full-Fill Electroplating → Cross-Section Validation → Copper Thickness Reduction → Outer Layer Pattern Transfer → Etching → AOI Inspection → Post-Fabrication Processes
Note: Stacked microvias require 100% void-free filling of inner layer microvias to ensure interlayer connection reliability, with additional copper thickness control to meet surface copper uniformity requirements.
Microvia Filling Technologies
We adopt two industry-standard via filling solutions, with full process capability for high-volume production:
- Electroplated Via Filling: Our mainstream production process, which achieves 100% void-free filling of microvias through pulse electroplating. It delivers excellent surface flatness (dimple < 10μm), superior electrical conductivity and thermal performance, and is fully compatible with subsequent soldering and fine-pitch SMT assembly.
- Resin Plug Hole: Fills vias with high-temperature modified epoxy resin after copper wall plating, followed by surface copper plating. It achieves a completely flat surface with no dents, ideal for high-layer-count HDI designs with via-in-pad requirements, eliminating soldering risks and improving assembly yield.
MaxiPCB HDI Manufacturing Capabilities
| Parameter |
Mass Production Capability |
Prototype Capability |
| Layer Count |
4 - 24 Layers |
Up to 36 Layers |
| Minimum Line Width/Spacing |
2/2 mil (50/50 μm) |
1.5/1.5 mil (35/35 μm) |
| Minimum Laser Microvia Diameter |
75μm |
50μm |
| Impedance Control Tolerance |
±5% |
±3% |
| HDI Tier Support |
Up to 6th Order HDI |
Up to 8th Order Anylayer HDI |
| Via Filling Solution |
Electroplated Via Filling / Resin Plug Hole |
Customized Filling Process |
Quality & Compliance
All our HDI PCB products are manufactured in strict accordance with IPC-6012 Class 2/Class 3 standards, with a full closed-loop quality management system covering incoming material inspection, in-process SPC control, and finished product reliability testing. All products fully comply with RoHS, REACH and other global environmental regulations, with stable batch consistency for both prototype and high-volume production.
With over 10 years of HDI PCB R&D and manufacturing experience, MaxiPCB has a professional engineering team and dedicated HDI production lines, specializing in high-reliability, high-complexity HDI PCB solutions for communications, consumer electronics, automotive electronics, medical devices, aerospace and other industries.
