Everything To Know About High-Density PCB


In a few years, printed circuit boards have evolved. From simple single-layer PCBs, there are now high-quality circuit boards such as High-Density Interconnect Printed Circuit Boards.

HDI PCBs are more complex than standard PCBs. This means they are used in electronic devices that require better signal integrity. To help you understand more about circuit boards, here is everything you need to know about HDI PCBs.

What is High-Density Interconnect PCB (HDI PCB)?

An HDI PCB is a type of circuit board with several interconnections but occupies a small space. The elements are placed closer and the space of the board is significantly reduced. However, the functionality is not compromised.

Since standard PCBs cannot accommodate many components in smaller circuit areas, HDI PCBs permit the manufacturer to fit more elements. A circuit board with an average of a hundred and twenty to a hundred and sixty pins per square inch is known as a High-Density Interconnect circuit board.

HDI PCBs are mostly used in digital cameras, cell phones, laptops, digital products, and automotive electronics among others.

Structure of an HDI PCB

HDI-printed PCBs are multilayer circuit boards whose layers are populated with copper and lines. In addition, several vias are used and allow the layers to be electrically interconnected. The whole board is held together through a lamination process.

The layers are interconnected using various types of vias. During the lamination process, the etching of copper layers is the first process. They are then separated by cured laminates. Here, they are stacked with prepreg on the top and at the bottom.

The whole stack-up is heated to liquefy the prepreg. After cooling the prepreg, it solidifies and the stack up is held together. To improve routing density, designers increase the number of layers to come up with a more complex stack-up.

Advantages of HDI PCB

HDI-printed circuit boards come with numerous benefits. This has made them popular in various sectors. Below are the main advantages of HDI PCBs.


HDI PCBs are good in the placement of standard PCBs when space, weight, and performance are the main concerns. With them, it is possible to fit many components into the board. The manufacturers use buried, blind, and micro vias to reduce the size of the board.

Better signal integrity

By placing elements together through blinds and buries to connect them, the signal path length is reduced. Hence, the technology helps to get rid of stubs thus enhancing signal quality. It also makes them less prone to thermal degradation.


It is possible to have the functionality of a standard 8-layer through-hole standard circuit board reduced to a 6-layer HDI board without interfering with the performance and the quality of the board.

High reliability

The introduction of stacked vias ensures the boards are strong and can withstand extreme environmental conditions.

Difference between HDI PCBs and Ordinary PCBs

There are several key differences between ordinary PCBs and HDI PCBs. From performance to quality, HDI PCBs are more popular than standard circuit boards. Here are the main differences between HDI and standard PCBs.

*HDI PCBs are smaller, lighter, and more powerful. On the other hand, normal PCBs are larger, heavier, and less powerful than HDI circuit boards.

*With HDI, the implementation is of blinds, buried, and micro vias. This board is hard to fabricate, which needs laser drilling or precise CNC machining. But with standard PCBs, the implementation is through holes.

*HDI PCBs have a lower number of layers while ordinary circuit boards have a higher number of layers.

*High-density interconnect PCBs are compatible with higher pin count gadgets and small pitch gadgets while standard circuit boards are sometimes not compatible.

Types of HDI PCBs

There are three types of HDI PCBs namely Type I, Type II, and Type III.

Type I – this is an HDI type that comes with a laminated core and uses a through hole for connectivity. Nevertheless, it does not have buried vias in its stack up.

Type II – is an HDI PCB that has a sequentially laminated core. It makes use of one micro via a layer on both sides of its core. It comes with both micro vias and PHT for interconnectivity.

Type III – this type of HDI PCB has a laminate core with micro vias on each side of the board. It uses both blind and buried vias. In addition, the manufacturers use staggered and stacked micro vias.

Applications for HDI PCBs


HDI PCBs have benefited the healthcare industry in a big way. This is because most medical equipment uses HDI since it can fit well in small devices. Some of the medical gadgets that use HDI PCB include implants, imaging gadgets, and lab equipment.

HDI PCBs have also made it possible to accommodate advances in medical cameras. These are small cameras that are used to observe the inner parts of the patients.

Tablets and smartphones

Smartphones and tablets are other devices that use HDI PCBs. The HDI PCBs have made it possible for manufacturers to create smaller and thinner portable electronic devices.


Today, vehicle manufacturers are attracted to small PCBs. This is because they are able to save space in the car. Moreover, today there are many smart devices installed inside cars.


HDI PCBs are essential components when manufacturing military equipment. This is because they can withstand harsh environments.


Just like in military applications, HDI PCBs are ideal for aerospace applications. This is because they are small, light, and suited for extreme environments.

Wearable technology

With the launch of smartwatches, HDI PCBs have become vital in wearable technology. The demand is high in this sector because wearable technology has become popular among the young generation.


Printed circuit boards have changed the electronic industry. This is because they are used in all modern electronic devices. Moreover, the demand for PCBs is promising since almost all industries require them.

HDI PCBs are some of the most used circuit boards. This is because designers can create smaller and lighter devices with HDI PCBs. Moreover, it is possible to get an enhanced signal in a reduced size.


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