HDI printed circuit boards (High Density Interconnect) offer the finest trace structures, the smallest holes and Blind & Buried Vias (Microvias). HDI technology enables a highly compact, reliable printed circuit board design. Also applied are Via-in-Pad and multiple microvia-layers (Stacked & Staggered Vias).
For Via-in-Pad applications, via holes are placed directly in the solder pads, saving valuable space. With a reliable Via Filling / Capping process, without enclosures of chemicals, it is possible to produce high-density PCB designs with Via-in-Pad technology, avoiding soldering errors (see Filled & Capped Vias). Amongst other things, this faciliates additional conductor traces for BGAs.
Pressing of additional layers through SBU (Sequential Build-Up) or SSBU (Semi Sequential Build-Up) technology enables routing on the inner layers, with space left on the outer layers for components with high pin density.
IPC-6012D defines HDI-Printed Circuit Boards et al. with drills ≤ 0.15mm (6mil) and track width/ -space ≤ 0.1mm (4mil).
State-of-the-art production equipment and over 25 years of experience in printed circuit board technology enable Multi-CB to offer process-reliable, cost-effective solutions for HDI circuit boards! 0.1mm tracks as well as 0.2mm drills are already standard technology with Multi-CB (without surcharge).
HDI-Printed Circuit Boards definition of terms
- Blind Via: Contacting of an outer layer ending on an inner layer
- Buried Via: Through-hole in the core layers
- Microvia: Blind Via (coll. also via) with a diameter ≤ 0.15mm
- SBU (Sequential Build-Up): Sequential layer buildup with at least two press operations on multilayer PCBs
- SSBU (Semi Sequential Build-Up): Pressing of testable substructures in SBU technology
Advantages of HDI-Printed Circuit Boards
The most common reason for using HDI technology is the significantly higher packing density. The space, which is obtained by finer track structures and Microvias, is available for components and their landing surfaces. In addition, the overall space requirement decreases, which results in a smaller board size and a reduced number of required layers.
Often FPGAs or BGAs are only available with a pitch of 1mm and less. HDI technology makes it easy to route and connect, especially when tracks are routed between the pins.
Reasons for HDI PCBs
Price savings through HDI-Printed Circuit Boards
- Higher packing density
- Less layers
- Smaller circuit board
- Miniaturization increases competitiveness
Improved features by HDI-Printed Circuit Boards
- Denser trace routing
- More stable power supply
- Reduction of disturbing inductance and capacitance effects
- Improved signal integrity in high-speed designs
HDI-Circuit Printed Boards enable high-tech
- Higher packing density
- Enables placement of BGAs with the smallest pitch
- Easier placement for CSP (Chip Scale Package) or Flip Chip
Faster development with HDI-Printed Circuit Boards
- Easier placement of SMD components
- Faster routing
- Reduction of frequent relocation of components
- More space for components (also by Via-in-Pad)
Higher reliability through HDI-Printed Circuit Boards
- Microvias have a very high reliability
- Improved thermal properties (thin insulation layers, HTg material)
- Future-proof technology as components become smaller and smaller
Microvias in HDI circuit boards
A microvia has typical diameters of 0.15mm (6mil) - 0.1mm (4mil) and can be drilled by laser (standard) or mechanically. Due to a small annular ring of only 0.1mm, the microvia pad has a diameter of only 0.3mm (12mil), which means an enormous space-saving compared to conventional Via pads.
Via | Annular ring | Via pad | Notes | |
---|---|---|---|---|
Traditional | 0.3mm | 0.15mm | 0.6mm | |
Multi-CB Standard | 0.2mm | 0.1mm | 0.4mm | without surcharge |
HDI-Technology | 0.1mm | 0.1mm | 0.3mm | special production |
Technically possible | 0.075mm | 0.075mm | 0.225mm | extreme special production |
Microvias are also available in these applications: Via-in-Pad, Stacked Vias, Staggered Vias filled with non-conductive paste and Filled & Capped Vias (metallized and planarized). Microvias offer a special added value when routing Finepitch BGAs with 0.8 mm pitch and below. They also have better electrical properties than conventional "thick" vias or Blind Vias.