What is a High Density Interconnect?
High Density Interconnect
The high density interconnect (HDI) is an advanced printed circuit board technology that allows for a higher number of connections and a smaller footprint than traditional PCBs. It offers greater reliability, faster signal functioning, and improved electronic device functionality. The HDI PCB is a multilayer PCB that contains several layers of copper traces and pads. Each layer is connected to the other through vias, which are tiny conductive holes that connect multiple layers in the PCB. There are four different types of vias in a high-density PCB: Through Hole Vias, Blind Vias, Buried Vias, and Microvias. Each of these is a different type of hole and is used for connecting different layers in the PCB.
Through-Hole vias are pierced using a drill or laser through the multilayer high density interconnect PCB to connect all internal layers. This type of via is also called a Plated Through Hole (PTH). The other three types of vias are Blind and Buried vias. The Blind and Buried vias are not visible from the outside of the PCB and they connect only specific internal layers. The Blind and Buried vias are plated with metal, which makes them conductors.
A high-density PCB is a multilayer PCB with densely routed layers and smaller vias. These features allow designers to build a complex stack-up for their designs without increasing the thickness of the PCB. The stack-up is fabricated by a series of sequential laminations of pre-cured laminates called prepregs. The prepregs are heated to a temperature that liquifies them and sticks them together. The resulting stack-up is then etched and soldered to the copper layers on both sides of the PCB.
What is a High Density Interconnect?
One of the most important features of a high-density PCB is via-in-pad, which connects the component solder pads to the board through the conductive path in the middle of the stack-up. This allows for shorter trace lengths, which leads to smaller boards and lower power consumption. It also reduces the amount of solder needed for connection, which saves money and resources.
High-density PCBs can be made with a variety of materials, including standard polyimide, FR-4 and FR-5. However, they are most often manufactured with a FR-4 material. This is because FR-4 is less expensive than other materials and is still durable enough for most applications.
A good FR-4 material has a thickness of 1.6-2.7 mm. This thickness is ideal for many high-density applications because it is a durable, insulating material that can protect the components and the copper traces from oxidation. Moreover, it is an environmentally friendly material. It does not emit toxic substances when burned or melted, and it can be disposed of safely. It is also resistant to thermal stress and vibrations. In addition, FR-4 is easy to handle and can be drilled with precision. This makes it ideal for manufacturing high-density PCBs.