With the trend of electronic productsmoving towards miniaturization, high-speed operation, and high performance,traditional PCB technology is increasingly unable to meet the requirements ofcomplex circuit designs. High-Density Interconnect (HDI) technology, combinedwith Micro Blind Vias and Buried Vias, has become a key trend in modernPCB/PCBA design. This article introduces HDI and micro blind/buried viatechnology and analyzes their advantages and application prospects.

1.Overview of HDI Technology

HDI is a high-density PCB technology thatachieves more compact and higher-performance circuit designs by using smallervias, higher layer counts, and high-precision interconnections. The mainfeatures of HDI boards include:

Micro blind and buried via technology:Enables high-density interconnections between multiple layers while reducingthe use of outer layer space.

Higher wiring density: Trace spacing can beless than 100 µm, supporting complex circuit designs.

Improved signal integrity: Shorter signalpaths reduce crosstalk and signal attenuation, suitable for high-speed signaltransmission.

HDI technology can be classified accordingto interconnection type into single/double-sided micro blind via HDI and buriedvia HDI. Micro blind vias primarily connect outer layers to inner layers, whileburied vias exist only between inner layers and do not penetrate outer layers,making them suitable for high-layer-count and complex PCBs.

2.Micro Blind and Buried Via Technology

2.1 Micro Blind Via

Micro blind vias connect only the outerlayer to inner layers without going through the entire board. Their advantagesinclude:

Saving PCB area, allowing higher wiringdensity

Reducing crosstalk and improving high-speedsignal performance

Can be combined with laser drillingtechnology for high-precision, small-diameter vias

2.2 Buried Via

Buried vias exist between inner layers anddo not affect outer layer layouts. The main advantages are:

Maintain a flat outer layer, facilitatingSMT assembly

Support compact design of high-layer-countPCBs

Improve board mechanical strength andreduce stress concentration

3.Advantages of HDI with Micro Blind/Buried Vias

Reduced PCB size: HDI allows more routingin the same area, meeting the miniaturization requirements of portable devices.

Enhanced performance: Shorter signal pathsand controlled impedance are beneficial for high-speed and high-frequencycircuit designs.

Improved reliability: Micro blind andburied via designs reduce solder joint stress and enhance mechanical andthermal performance.

Support for complex applications: Such asmulti-layer PCBs and rigid-flex boards.

4.Application Areas

HDI technology and micro blind/buried viasare widely used in multiple industries:

Consumer electronics: Smartphones, tablets,wearable devices

High-speed communications: 5G basestations, networking equipment, high-speed data interfaces

Automotive electronics: ADAS systems,electronic control units (ECUs)

Medical devices: Portable diagnosticinstruments, implantable devices

Industrial automation: Robot controlboards, high-precision sensors