HDI Printed Circuit Boards Manufacturer

High-quality, Short lead time, Affordable price

What is HDI PCB?

HDI PCBs or high-density interconnect PCBs are circuit boards with higher wiring density per unit area than standard printed circuit boards. They are light weight and compact PCBs with a lesser number of layers. 

HDI PCBs may have micro vias, blind and buried vias, finer spaces and lines, built-up laminations, and higher connection pad density. Electrical components are getting smaller and more lightweight every day. HDI PCBs help you to pack the functionality in these small components. However, the placement of the miniature pads and fine pitches require extra precision.

HDI PCBs are of different types, namely:

  • Through vias from surface to surface
  • Buried vias and through vias
  • Through vias in at least two layers
  • Coreless construction with layer pairs
  • Alternate coreless construction with layer pairs
  • Passive substrate without any electric connection

The different features of the HDI PCBs include high-speed signal, impedance control, high-frequency transmission capability, and decreased redundant radiation. One HDI PCB can pack the functionality and cost of multiple PCBs in an electrical device.

Benefits of using HDI PCB

The benefits of HDI PCBs lie in their capability of doing more with less. If you use an HDI PCB, you can get the following benefits:

  • Compact size and lightweight: HDI boards can secure many components on both sides of a PCB. As a result, PCB gains more functionality while decreasing the size and weight of the PCB and the products.
  • Cost-effectiveness: When designed with proper planning and manufacturing, these PCBs can cost you way less than the standard PCBs due to their small & compact size and lesser number of board layers required. If a device needs multiple standard PCBs, you can complete the work with just one HDI PCB.
  • High electrical performance: Many transistors and a smaller distance between different electrical components improve HDI PCBs’ electrical performance. As a result, it leads to lower power consumption and better signal integrity. Further, its small size will ensure reduced signal losses and crossing delays.
  • Quick production times: As these PCBs use few materials and few boards and deploy efficiency and technical methods of designing, it leads to short production cycles. Also, the ease of placing components and the high electrical performance of the HDI PCBs reduce testing and troubleshooting time. Thus, you get your products faster in the market.
  • Highly reliable: The smaller aspect ratio and high construction quality of microvias make these PCBs highly reliable. With better reliability, you get high-performing products.

HDI PCB structure

HDI PCBs have a symmetrical structure having inner and outer layers. The outer layers clamp the inner ones while the inner ones are the PCB’s symmetry axis part. These layers have separate penetration by buried vias. If the HDI PCB structure is not symmetrical, it can lead to non-performance of the boards.

Based on your design requirements, you can choose from different HDI printed circuit boards structures to get desired performance.

  • HDI PCB (1+N+1): Simplest HDI

This HDI PCB structure has a single build-up of high-density interconnected layers that requires only one laser drilling. This structure is ideal for BGA with lower I/O counts. It features fine lines, microvia, strong mounting stability, high reliability, registration technology of 0.4mm ball pitch, and may have copper-filled vias. You can use this on cell phones, GPS, MP3 players, and Memory cards.

  • HDI PCB (2+N+2): Moderate Complex HDI

This type has two or more than two build-ups of highly dense interconnection layers and thus requires multiple laser drillings. In this, microvias on the outer layers may overlap and form stacked via, or they may not overlap and create a staggered via. As the piling and overlapping of microvias on outer layers require high precision, stacked, HDI PCBs are more expensive than staggered ones. 

You can use stacked PCBs in applications that require high-speed signal transmission like in-game consoles, PDAs, cell phones, and portable video recording equipment. These PCBs are ideal for BGA with small ball pitch and higher I/O counts.  

  • ELIC (Every Layer Interconnection): Most Complex HDI

In this structure, every layer is a high-density interconnection layer. As a result, conductors on any layer can connect to the copper-filled stacked microvias. Highly complicated pin-count devices like CPU and GPU in mobile devices use these PCBs.

Design consideration for HDI PCB

HDI PCBs production process requires some design considerations that you must keep in mind. Here is a brief description of all those HDI PCB design considerations.

Sequential Lamination: In this heat and pressure helps in forming multilayer PCBs by combining PCB core/cores with copper and prepreg layers. The heat and pressure required may vary from board to board. Once the lamination is complete, manufacturers drill the vias. In HDI PCBs, this process occurs multiple times to ensure no shifting and breaking of boards during drilling.

Via-in-Pad process: With the via-in-pad process, manufacturers can place the vias on the flat surfaces of the PCBs. This step involves plating the vias, filling it with one of the fill types, capping it, and finally plating over it to make it invisible. It requires special equipment and highly skilled technicians to complete the via-in-pad process. This process is preferred for HDI PCBs as it needs less space, simplifies thermal management, and easily bypasses capacitors.

Via Fill Types: There are different types of Via fill types available. You can choose from conductive epoxy, silver-filled, copper-filled, electrochemical plating, and non-conductive epoxy. These via fill types flushes in the flatlands and solders completely. After this, vias and microvias get drilled, blind and buried, plated, and hidden beneath SMT lands. This Via process is time-consuming as multiple drill cycles need controlled depth drilling. Also, the process requires special equipment to complete the process.

Laser Drill Technology: Every layer in HDI PCB requires laser drilling to create microvias. These drills create a laser of 20 microns in diameter, creating tiny and clean holes in either a glass or a metal. If you want smaller holes, you can choose uniform glass materials having a low dielectric constant.

LDI and Contact Imagery: Processing the HDI PCBs require imaging finer lines and creating clean rooms. The process may be expensive but essential too. These fine lines and annular rings require high precision. At….you can find cutting-edge technology for this delicate detailing so that you do not need any repairs in the future. Contact imaging and laser direct imaging are the two well-known methods of creating these fine lines. However, contact imaging is more popular due to the expensive nature of LDI, but LDI can handle the most demanding processes.

Application of HDI PCB in the industries

Today, many advanced technologies use HDI PCBs as their critical component. PCBs and electric components are getting smaller and smaller, and thus, you get very compact and cost-effective devices without affecting their performance and reliability. 

The below list mentions some industries which use HDI PCBs.

Consumer electronics: Remember the times when computers used to acquire big rooms. Thanks to these small components, your smartwatches are a type of personal computer. Your laptops, tablets, smartphones, wearables, and other electronics have HDI boards. Several IoT devices in your home, like fridges, smart thermostats, and other connected devices, use HDI boards. The HDI is becoming popular with these smart devices.

Communications: Some other devices that give functionality to your laptops and smartphones, like routers, modules, switches, and semiconductors, also use HDI PCBs. If you are using any electronic communication (a device that uses radio waves), there is a high possibility that you may be using an HDI printed circuit board. Additionally, you may find HDI technology in digital video and audio equipment.

Automotive and Aerospace: As HDI PCBs are compact and lightweight, manufacturers can design devices that fit into small spaces and weigh less. These devices are beneficial in the automotive and aerospace industries as lightweight devices promote better operation. If you look at your car, you will see that it is getting more computerized daily. Your vehicle may have around 50 microprocessors that help in safety features, diagnostics, engine controls, etc. In addition to this, your onboard Wi-Fi and GPS, backup sensors, and review cameras also use HDI PCBs.

Medical devices: modern electronic medical devices used for imaging, monitoring, surgical procedures, and other uses use HDI boards. The HDIs have high-density technology, so you get better performance and higher accuracy in these small, cost-effective testing and monitoring devices. 

Industrial usage: HDI technology is creeping into industrial equipment too. Nowadays, industries use several IoT devices for manufacturing, warehousing, packaging, etc. Many businesses are also using various electronic tools to manage inventory and monitor the performance of the equipment. Many industrial machines use smart sensors that help collect the data and communicate this information to other smart devices.