HDI High-Density Interconnect
HDI PCBs capitalize on the latest technologies available to increase the functionality of PCBs using the same or less amount of area. This advancement in PCB technology is driven by the miniaturization of components and semiconductor packages that supports advanced features in revolutionary new products. This includes touch screen computing, 4G network communications, and military applications such as avionics and smart munitions.
Highfive HDI Rigid Flex Prototype PCB Layout Rules AI PCB
Micro Vias for High-Density Attributes HDI
HDI PCBs are characterized by high-density attributes including laser micro vias, fine lines, and high-performance thin materials. This increased density enables more functions per unit area. Higher technology HDI PCBs have multiple layers of copper filled stacked micro vias which creates a structure that enables even more complex interconnections. These very complex structures provide the necessary routing solutions for today’s large pin-count chips utilized in mobile devices and other high technology products.
HDI Structures
1+N+1 – PCBs contain 1 “build-up” of high-density interconnection layers.
i+N+i (i≥2) – PCBs contain 2 or more “build-up” of high density interconnection layers. Micro vias on different layers can be staggered or stacked. Copper filled stacked micro via structures are commonly seen in challenging designs.
Any Layer HDI – All the layers of a PCB are high-density interconnection layers which allow the conductors on any layer of the PCB to be interconnected freely with copper filled stacked micro-via structures (“any layer via”). This provides a reliable interconnect solution for highly complex large pin-count devices, such as CPU and GPU chips utilized on handheld and mobile devices.
Advanced Capabilities: Micro Vias HDI
A micro via maintains a laser-drilled diameter of typically 0.006″ (150µm), 0.005″ (125µm), or 0.004″ (100µm), which are optically aligned and require a pad diameter typically 0.012″ (300µm), 0.010″ (250µm), or 0.008″ (200µm), allowing additional routing density. Micro vias can be via-in-pad, offset, staggered or stacked, non-conductive filled and copper-plated over the top, or solid copper filled or plated. Micro vias add value when routing out of fine pitch BGAs such as 0.8 mm pitch devices and below.
Micro vias HDI add value when routing out of a 0.5 mm pitch device where staggered micro vias can be used, however, routing micro-BGAs such as 0.4 mm, 0.3 mm, or 0.25 mm pitch device, requires using an inverted pyramid routing technique.
Highfive maintains years of experience with HDI products and was a pioneer of second-generation micro vias that offers solid copper stacked micro vias providing rout-out solutions for micro HDI BGAs.
Standard or First Generation Micro vias HDI
Create routing density (eliminate through vias)
Reduce layer count
Enhance electrical characteristics
Standard Microvias limited to layers 1 – 2 & 1 – 3
Second Generation Micro vias HDI
Allows increased routing on multiple layers
Provides routing solutions for next generation applications
1 mm – 0.8 mm – 0.65 mm – 0.5 mm – 0.4 mm – 0.3 mm & 0.25 mm
Provides solid copper plate eliminating potential solder voiding
Provides a Thermal Management Solution
Improves Current Carrying Capability
Improves Current Carrying Capability
Provides a Planar surface for BGA (Via-in-Pad)
Allows any layer via technology
Deep Stacked Micro Vias HDI
Provides additional dielectric for RF applications
Maintains small geometries on multiple layers
Improved signal integrity
Provides a solid copper plate
Improves Current Carrying Capability & Thermal Management
Provides a Planar surface for BGA (Via-in-Pad)
Highfive PCBAE developed and now offers generation microvias which offers stacked microvia fabrication in a timely manner (5-7 days). And allows for a quick-turn of PCB designs with complex via structures and requires only one lamination cycle reducing thermal excursions (thermal degradation of material) and cycle time.
It eliminates the copper plating cycle of inner layers, improving impedance tolerance, reducing overall thickness and improving electrical characteristics. Additionally, it can provides designer flexibility to have any-layer-via connectivity using a metallurgical bond between conductive paste and copper on the inner layers. It can also be utilized for the surface or external microvias to create a solid copper via if required.
Additionally, HDI allows interconnecting of multiple subs containing high technology or standard technology. Also, this technology allows the use of high performance materials only where they are needed or required.