HDI printed circuit board reduce signal loss
The circuit boards of modern electronics are packed with high-tech features that make them more efficient and powerful. However, their small size and densely packed circuitry imposes a number of challenges in terms of signal integrity and power distribution. One way to overcome these issues is to use HDI printed circuit boards. This technology improves the performance of electronic devices by enabling them to carry more transistors. However, this additional functionality is possible only when the signals can travel quickly and reliably.
In order to achieve this, the board designer must focus on reducing the overall signal loss of the board. The signal path must be kept short, which can be achieved by using HDI PCBs. However, achieving this requires careful consideration of the design layout and manufacturing process.
An hdi printed circuit board consists of two types: build-up/sequential lamination and any-layer structure/every layer interconnect (ELIC). The former uses sequential construction, where core layers are built, laminated, drilled, plated, and filled in a single step. This method is used for specialized high-pin-count boards that require complex circuit structures.
How does an HDI printed circuit board reduce signal loss?
The latter has a multi-layer structure where conductors of different layers are connected through copper-filled microvias. This method is used for achieving higher pin-counts and higher speeds in electronic devices. The microvias in HDI PCBs are created using laser drilling techniques, which ensure a smaller hole diameter than traditional mechanical methods. The laser drills work at up to 20 microns in diameter, which creates small but clean holes. This technique also minimizes the amount of buried copper on the surface of the PCB.
Keeping the routing as simple as possible can reduce the signal-to-noise ratio (SNR) and power-to-noise ratio (PPR). Signal reflection, via stub length, and ground shielding have to be carefully optimized in the HDI layout to meet the required SI effect. Using blind and buried vias to connect inner layers can help reduce the impact of impedance mismatches on the signal. Putting decoupling capacitors close to ICs can reduce power noise.
Another factor to consider is the manufacturer’s capabilities and drilling capability. The drill-to-copper clearance has to be carefully considered, as it is critical for proper HDI routing. In addition, the manufacturer should be able to provide the right surface finishes for HDI PCBs.
Using the right surface finishes for your board can significantly improve the quality of your product. For example, ENIG or ENEPIG are preferred over soft gold because they offer better oxidation resistance and corrosion protection. These qualities can help you avoid problems such as shorts and defects, which will increase the reliability of your final product. Additionally, minimizing the number of staggered vias and Extra-Large Inner Connects (ELIC) can save money by lowering your PCB assembly costs. The type and amount of vias, through-holes or microvias in your design can also affect its cost. For the best result, you should always check with your manufacturer before deciding on the stackup, the number of layers and the type and quantity of vias you need for your design.
