HDI PCBs (High-Density Interconnect Printed Circuit Boards) are increasingly popular in today’s electronic devices. These PCBs use advanced manufacturing technologies to provide more functionality in a smaller space. The use of HDI PCBs can also improve signal integrity, reduce noise, and increase the reliability of electronic devices. In HDI PCB design, three types of holes are commonly used: Microvia, Buried Via, and Blind Via. In this article, we will discuss the applications of these holes in HDI PCB design.
Microvia
Microvia is a small hole with a diameter of less than 0.15mm drilled by laser technology. Microvias are typically used to connect two or more layers of the PCB. They are widely used in HDI PCB design to increase the density of interconnections and reduce the size of the PCB. Microvias are usually filled with a conductive material like copper to provide a reliable connection between layers.
The advantages of micro vias are numerous. Firstly, they reduce the PCB’s size, making it possible to design smaller and more compact devices. Secondly, micro vias can improve the signal integrity by reducing signal reflection and attenuation. Thirdly, micro vias can increase the reliability of the PCB by reducing the possibility of via cracking, which can occur during thermal cycling or mechanical stress. Finally, microvias can reduce the cost of the PCB by eliminating the need for through-hole plating and reducing the amount of drilling required.
Buried Via
Buried vias are holes drilled through several layers of the PCB but do not extend to the surface. Buried vias are used to connect the inner layers of the PCB, and they are typically used in designs with many layers. Buried vias are drilled after the inner layers of the PCB have been laminated together.
Buried vias are used in HDI PCB design to increase the density of interconnections and reduce the size of the PCB. They also help to improve signal integrity by reducing signal reflection and attenuation. Buried vias are filled with a conductive material like copper to provide a reliable connection between layers.
The advantages of buried vias are that they increase the density of interconnections, reduce the size of the PCB, and improve signal integrity. They also reduce the possibility of via cracking, which can occur during thermal cycling or mechanical stress. However, buried vias are more expensive to manufacture than micro vias and require more drilling.
Blind Via
Blind vias are holes drilled through some of the layers of the PCB but do not extend through the entire thickness of the PCB. Blind vias are used to connect the outer layers of the PCB to the inner layers, and they are typically used in designs with a small number of layers. Blind vias are drilled before the inner layers of the PCB are laminated together.
Blind vias are used in HDI PCB design to increase the density of interconnections and reduce the size of the PCB. They also help to improve signal integrity by reducing signal reflection and attenuation. Blind vias are filled with a conductive material like copper to provide a reliable connection between layers.
The advantages of blind vias are that they increase the density of interconnections, reduce the size of the PCB, and improve signal integrity. They also reduce the possibility of via cracking, which can occur during thermal cycling or mechanical stress. However, blind vias are more expensive to manufacture than micro vias and require more drilling.
Conclusion
In HDI PCB design, three types of holes are commonly used: Microvia, Buried Via, and Blind Via. These holes are used to increase the density of interconnections, reduce the PCB’s size, improve signal integrity, and increase the reliability of the PCB. Microvias are the smallest type of hole, and they are used to connect two or more layers of the PCB. Buried vias are used to connect the inner layers of the PCB, and they do not extend to the surface. Blind vias are used to connect the outer layers of the PCB to the inner layers, and they do not extend through the entire thickness of the PCB.
Each type of hole has its advantages and disadvantages. Microvias are the most cost effective and provide the highest density of interconnections, but they are unsuitable for designs with many layers. Buried vias and blind vias provide a higher density of interconnections than through-hole vias, but they are more expensive to manufacture and require more drilling. The choice of hole type depends on the specific design requirements and manufacturing capabilities.
In summary, HDI PCB design relies heavily on the use of microvias, buried vias, and blind vias to provide a high density of interconnections in a small space. These advanced manufacturing technologies can improve signal integrity, reduce noise, and increase the reliability of electronic devices. As the demand for smaller and more advanced electronic devices continues to grow, HDI PCBs and these types of holes will only become more important.
