HDI printed circuit board support miniaturization
With the ongoing trend towards smaller form factor electronic devices, it becomes critical to improve performance and functionality in a reduced footprint. Fortunately, advances in high-density interconnect PCB (HDI) technology have allowed manufacturers to achieve this by increasing component density and supporting more connections on an HDI board with thinner traces and vias. This allows a higher number of components to fit within a small size and also reduces the time it takes for signals to travel from one layer to another, resulting in better signal transmission.
To support this miniaturization trend, HDI PCBs have introduced innovations like microvias PCB and fine traces. Microvias are holes drilled with lasers, which are much smaller in diameter than mechanically drilled through-holes and enable the use of more layers in a PCB. This, along with a reduction in component size and pitch, helps to increase the number of circuits on the PCB and reduces the risk of signal loss or interference.
Besides being more compact, hdi printed circuit board have a faster time-to-market thanks to their ease of design and improved electrical performance. The shorter path that electrical signals must travel means they can be transmitted with greater speed, ensuring that all the information needed to function correctly is delivered.
How does an HDI printed circuit board support miniaturization?
However, while the advantages of HDI are numerous, it is important to remember that a well-designed circuit board is still required. This is because the manufacturing process used for HDI PCBs requires careful consideration of the fabricator limitations to ensure optimal performance. This includes proper component placement, routing and signal integrity considerations. In addition, a thorough fanout strategy must be used to ensure that the required pins can be routed to the correct location.
A key concern with the HDI process is that it can be costly if not properly implemented. The etching and imaging processes are a lot more involved than traditional PCBs, which leads to an increased chance of defects, particularly with the fine lines, spacing and annular rings. This is a result of the requirement for the use of semiconductor class 100 clean rooms to process the boards as well as the need to maintain very strict photo tool, laminate prep and imaging parameters.
To help mitigate the cost of HDI PCBs, the manufacturer can implement techniques like sequential lamination and landless via technology. This reduces the total number of layers in a circuit board by eliminating the need for buried or blind vias, which require multiple sequential laminations and can be costly. Additionally, the manufacturer can use ENIG or ENEPIG surface finishes for the copper layers, which reduces thickness by as much as 40% and further cuts the overall board costs.
An HDI PCB is often found in complex electronic devices that demand excellent performance while conserving space. These include mobile /cellular phones, digital cameras, laptop computers, touch-screen devices, 4/5G network communications and military applications such as avionics and smart munitions. It is also becoming increasingly common in medical equipment, such as pacemakers and diagnostic and monitoring systems.