Growing Demand for HDI Boards
According to Prismark statistics, with the development of the global electronic information industry, the global PCB market output value is expected to reach $55.3 billion in 2017, the compound annual growth rate is about 2.2% from $54.2 billion in 2016 to $60.4 billion in 2021. Electronic products show two obvious trends: one is thin and small; another is high density interconnect.
In the future, the in-depth usage of large-scale integrated circuit will further drive PCB boards towards higher precision and high-level. HLC board, featuring short wiring length, low circuit impedance, high frequency, high speed and stable performance, can assume more complex functions, is the inevitable electronic technology trend for high-speed high-frequency, multi-functional large-capacity development. Currently, PCB boards less than 8-layer are mainly used for household appliances, PC, desktop and other electronic products, while high-performance multi-channel servers, aerospace and other high-end applications require PCB boards with 10+ layers.
Wiring density on HDI boards has obvious advantages than ordinary multi-layer boards, and become the mainstream of the current smart phone’s motherboard. Smart phone is more complex but lighter, leaving less and less space on the motherboard, requiring more components installed on a limited motherboard, ordinary multilayer boards is unable to meet this requirement.
HDI technical differences reflect on the board layer number, more number of layers means more difficult to fabricate. HDI can be divided into first-grade HDI, second-grade HDI, high-grade HDI, etc., and its layers are expressed as C + N + C, where N is the number of ordinary core layers, C is the number of layers that is HDI grade. Wiring density on high-grade HDI is higher, however, it also means more pressing times, which bring more difficult for manufacturers to drill, plate, etc.
HDI board adopts laminated system method to make board, using the ordinary multi-layer board as the core stack, using drilling and hole metallization process to realize the link function among layers of the circuitry. Compared to ordinary multi-layer boards only with through-holes, HDI boards accurately set blind holes and buried holes to reduce through-holes, saving more PCB wiring area, greatly improving the density of components, and thus replace multi-layer boards used in smart phones.