High Density Interconnect
The electronics industry has been evolving at a rapid pace and there has been a constant demand for higher functionality in smaller packages. This has led to the development of a special PCB variant known as High Density Interconnect (HDI). It is an advanced class of densely-packed multi-layer PCB technologies engineered for component packaging miniaturization, plus enhanced electrical and reliability performance to suit rising modern device integration challenges.
This technology uses a new design and fabrication process to enable a greater amount of circuitry to be packed into a shorter space without affecting the functioning or quality of the product. This is achieved by using smaller traces, vias and copper pads. It is also based on advanced microlithography processes that can produce fine geometries with much better signal function.
In a high density interconnect, there are several layers of copper-filled conductive pathways between the components that can be found in each layer. These conductive paths are called ‘microvias’ and are drilled through the layers using lasers. The number of layers used in a HDI board can vary from one to eight, with different configurations offering different routing options for the designers.
What is a High Density Interconnect?
As a result of these advancements, HDI boards can be thinner and lighter than conventional printed circuit board technology. This is beneficial for a variety of applications where the size and weight of the product is important, such as consumer electronics like smartphones and tablet computers, as well as wearable devices like smartwatches and VR headsets.
In addition to these advantages, HDI boards provide superior thermal integrity. By utilizing a unique construction method that is based on copper unrelieved layering, these advanced PCBs offer ideal heat dissipation, ensuring that increased component count doesn’t compromise functional operation under harsh operating conditions.
HDI PCBs are also commonly used in a wide range of other applications, such as aerospace and defense, as well as medical and automotive. The density and reliability offered by HDI PCBs make them the perfect choice for these environments, as they can withstand extreme environmental conditions and still provide a highly reliable electronic device.
During the manufacturing of an HDI board, it is essential to have a photomask created. A photomask is a clear film that contains the complete circuit layout and it serves as a template for the metal trace patterns. The photomask is then used in conjunction with innovative etching techniques to create the actual board. It is crucial that the photomask be carefully created, as even a small deviation from its intended placement can lead to a failure in the final product. This is why sophisticated photolithography machinery and etching methods like reactive ion etch are employed. Without these technologies, producing an HDI board would be a very challenging task.