(HDI) PCBs
A PCB is an electronic circuit board that is used in the design and production of a wide range of products. Traditionally, it is constructed using several layers of a core material and conductive tracks connecting via holes. While these traditional PCBs continue to serve a valuable purpose, new technologies are driving the development of high-density interconnect (HDI) printed circuit boards.
An HDI PCB is a type of printed circuit board that features a higher number of layers, smaller size and more components. These innovations make them ideal for use in a wide variety of applications that require a high-density, small footprint and high performance PCB solution.
While the overall design of an pcb hdi is similar to that of a standard PCB, the key difference lies in its construction process. In order to achieve the high-density of an HDI PCB, it must be built using a series of multi-step processes that are characterized by the use of different types of microvias. These vias connect the layers of a PCB and allow it to function as an integrated circuit.
High-Density Interconnect (HDI) PCBs
The first step in the fabrication process of an HDI PCB is the etching of the inner layers of copper. This process must be precise in order to ensure that all traces and holes are aligned correctly. This is because the metallization of an HDI PCB relies on the alignment of these elements in order to provide a high-density layout that delivers the necessary performance required for the end application.
After the etching process is complete, the inner layer copper is separated from the dielectric layers. Then, the various layers are stacked together like a book and held in place by partially cured laminates known as prepregs. The resulting structure is then heated and pressed in order to liquify the prepregs. Once the prepregs are liquified, they can be cooled down and stuck to each other in order to form an integrated circuit board.
To connect the various layers of an HDI PCB, it must contain both conventional plated through holes (PTH) and filled plated microvias. The latter are used in a “via-in-pad” design approach to increase density. This helps to reduce manual routing time while also improving signal integrity by allowing the component leads to be connected directly to internal layers.
In general, the via sizes in an HDI PCB are limited by the limitations of fabrication methods and ball pitch on BGA components. It is important to keep these limits in mind when designing an HDI PCB, as it will impact the resulting mechanical drilling and via formation capabilities.
Aside from enabling smaller components and a greater number of components per square inch, HDI technology can also lead to improved reliability in the final product. This is due to the reduced amount of cross delays and signal losses that are incurred when components are placed closer together. This leads to a more robust, reliable circuit board that is ideal for many different applications. These include consumer electronics, smart devices, industrial automation, and even avionics.
