What is a high density PCB board (HDI PCB)?
The HDI board is based on the traditional double panel as the core board, which is made by continuously accumulating. This circuit board made by a continuous layer is also called the Build-Up Multilayer (BUM). Compared with the traditional circuit board, the HDI circuit board has the advantages of "light, thin, short, small".
The electrical connection between HDI's plate layer is achieved by conductive pores, buried holes, and blind holes. Its structure is different from ordinary multi -layer circuit boards. A large number of blind holes are used in HDI boards. HDI PCB uses laser direct drilling, and standard PCB usually uses mechanical drilling, so the number of layers and high width ratio often decreases.
HDI includes the use of fine features or signal traces and spaces of 0.003” (75 µm) or less and laser-drilled blind or buried microvia technology. Microvias allow the use of micro-interconnects from one layer to another within a PCB utilizing a smaller pad diameter creating additional routing density or reducing form factor.
High-density interconnect (HDI) PCBs are characterized by finer lines, closer spaces, and more dense wiring, which allow for a faster connection while reducing the size and bulk of a project. These boards also feature blind and buried vias, laser ablated microvias, sequential lamination, and via in-pads. As a result, a HDI board can house the functionality of the previous boards used. HITECH CIRCUITS is an HDI PCB manufacturer and provider in Shenzhen, China supports HDI PCB prototype and mass production with less expensive price and quick-turn lead time. Customers from a variety of industries we serve have a common that have high expectations in quality, reliability and on-time delivery in HDI PCB production. Our quality is not afterthought, but built into each process from front-end to fabrication and shipping.
HDI PCB's advantages
1. Reduce PCB cost: When the density of PCB increases beyond the eight-layer board, it will be manufactured in HDI, and the cost will be lower than that of traditional complicated press-forming process.
2. Better reliability: Due to the thin thickness and the aspect ratio of 1:1, the micropores have higher reliability when transmitting signals than ordinary through holes.
3. Improves thermal properties: The insulating dielectric material of the HDI board has a higher glass transition temperature (Tg) and therefore has better thermal properties.
4. Improve RF interference / electromagnetic interference / electrostatic discharge (RFI / EMI )
5. Increase design efficiency: Micro-hole technology allows the circuit to be arranged in the inner layer, so that the circuit designer has more design space, so the efficiency of the line design can be higher.
HDI PCB Manufacturing Process
The overall process for manufacturing HDI PCB is essentially the same as for fabricating other PCB board, with notable differences for PCB stack-up and hole drilling. Since HDI boards generally require smaller drill holes for vias, laser drilling is usually required. Although laser drills can produce smaller and more precise holes, they are limited by depth. Therefore, a limited number of layers can be drilled through at a time. For HDI boards, which are invariably multilayer and may contain buried and blind vias, multiple drilling processes may be required. This necessitates successive layer boding to achieve the desired stack-up or sequential lamination cycles. Not surprisingly, this can significantly increase PCB manufacturing time and cost. HDI PCB fabrication is an advanced technology and therefore requires expertise along with specialized equipment like laser drills, laser direct imaging (LDI) capability, and special clean room environments. In order to efficiently manufacture high-quality and reliable HDI PCB products, you must understand the HDI board manufacturing process and coordinate with your HDI PCB supplier to implement good DFM (Design for Manufacturability) for HDI layout design. Therefore, not all board factories have the ability to do the HDI, but Hitechpcb can, we will be here to support our customer needs.
