HDI PCBs capitalize on the latest technologies available to increase the functionality of PCBs using the same or less amount of area. This advancement in PCB technology is driven by the miniaturization of components and semiconductor packages that supports advanced features in revolutionary new products such as touch screen computing and 4G network communications,now it is 5G time,any layer technology is required for PCB .
HDI PCBs are characterized by high-density attributes including laser microvias, fine lines and high performance thin materials. This increased density enables more functions per unit area. Higher technology HDI PCBs have multiple layers of copper filled stacked microvias (Advanced HDI PCBs) which creates a structure that enables even more complex interconnections. These very complex structures provide the necessary routing solutions for today's large pin-count chips utilized in mobile devices and other high technology products. Most HDI boards are with burried/blind vias from 0.076-0..127mm.
Vias for HDI is 3-5 mil (0.076-0.127mm),line width is from 3-4mil(0.076-0.1mm). 0.8mm /0.5mm pitch BGA is usually for 1+N+1. Another thing is many customers did not know HDI board have to use special material--RCC (Resion Coated Copper),0.08mm thickness with copper.
0.4mm pitch BGA, means the space from BGA ball to another BGA ball is 0.4mm.
Many PCB designers do not know much how to design 0.4mm pitch BGA board,they make things very difficult to do .Here is a 0.4mm pitch BGA PCB design guide from TI OMAP processor. Pages 8 through 12 talk about pads, mask and vias. Obviously, you should consult similar materials written specifically for the part you are using, but Ti did a great job of covering all the issues here.
HDI-HIGH DENSITY INTERCONNECT PCB Any layer/ELIC (Every layer interconnection)
2022 03/01