HDI PCBs are making a big impact in many industries. This is largely due to their high performance and excellent quality. They also have a very short turnaround time. However, implementing HDI design requires careful planning and special equipment to manufacture.
It’s important to adhere to design rules, including minimum trace widths and clearances. It’s also necessary to plan for a proper stack-up and microvia structures.
Material
Despite being smaller than traditional PCBs, HDI boards can still deliver the performance, durability and reliability that customers need. The technology is also making a mark in the medical industry. Its small size means that it can fit in medical equipment like imaging equipment and miniature sized cameras, which help doctors to diagnose patients without compromising on picture quality.
It is essential to choose the right materials for HDI PCBs. The material must be able to withstand high temperatures and have good electrical properties. It should also be able to resist high-frequency signals. In addition, it must be able to meet the manufacturing requirements of the traces and the circuitry.
The fabrication process for HDI PCBs involves a number of steps, including laser drilling and sequential lamination cycles. This technique provides good control over the final thickness of the board and reduces the risk of warping. The drilled holes are then filled with either electrochemical plating, conductive epoxy or a conductive paste containing silver or copper. The resulting filling should sit flush with the land to form a flat solderable surface.
It is also important to consider the heat dissipation of HDI PCBs when designing them. If heat is not properly dissipated, the components can overheat and cause failure of the circuitry. It is therefore necessary to incorporate thermal vias into the design.
Vias
The vias used in HDI PCBs are a critical component of the design process. They must be designed with precision to avoid EMI/EMC issues and signal interference. The vias must also be carefully sized and located to minimize the number of layers required for routing. This allows the components to be closer together, which reduces the length of the signal paths and enhances signal integrity.
The most common types of HDI vias are blind and buried vias, which are used to connect the different layers in the multilayer board. These are created by laser drilling to hdi pcb design a controlled depth, which ensures that they are filled with copper and not just air. The drilled holes are then capped with copper. These vias are essential to reduce the layer count in HDI circuit boards.
Another type of HDI via is the through-hole microvia, which requires a higher level of precision to avoid impedance mismatches and signal interference. Through-hole microvias can hdi pcb be used to connect different layers of the PCB, but they can also be used to make contact with BGA components on the surface of the board.
There are two standard structures for HDI circuit boards: the Sequential Build-Up structure and Every Layer Interconnect (ELIC). The Sequential Build-Up structure consists of several laminations that must be laminated, etched, and plated separately. It is most suitable for complex designs that require high-level signal transmission performance, such as those found in mobile devices and portable video recording devices.
Stack-up
A proper stack-up is crucial for HDI PCBs. It allows for a high level of circuit density and improves signal integrity. It also reduces ground bouncing effect, which can cause noise and EMI. Additionally, it provides a return path for high-speed signals, which helps to reduce EMI and crosstalk. The stack-up is also important in ensuring that the signal layers are isolated from power and ground planes. This will ensure that the signal can travel over shortest distances with minimum impedance and will minimize power losses.
The type and number of vias, microvias, and through-holes you use in your stack-up will impact the manufacturing cost of your HDI board. The more features you add, the higher your PCB’s price will be. In order to reduce costs, you can try to use smaller via sizes and avoid overusing microvias and through-holes.
Choosing the right stack-up configuration for your HDI PCB depends on the specific requirements of your design. You should choose a configuration that is appropriate for your application’s power and signal density, impedance needs, and EMI shielding requirements. Additionally, you should consider the layer count and copper trace widths.
There are several types of HDI stack-ups, including i+N+i and 2+n+2 designs. Each of these options has its own benefits and disadvantages, but they all offer great routing flexibility. These configurations allow you to use blind microvias and buried vias, which can help you achieve greater routing freedom and reduce the overall thickness of your board.
Layout
HDI PCBs require advanced layout and routing techniques to achieve a high wiring density. These PCBs also require special materials and processes to fabricate, including laser drilling, laser direct imaging and sequential lamination cycles. The layout of a HDI PCB is crucial to its performance, and it should be considered carefully throughout the design process. It should take into account the type and amount of vias, through-holes or microvias, stack-up height, and component placement.
Through-holes and microvias are the main methods used to connect layers in an HDI PCB, but there are also other options. For example, buried vias can be used to connect multiple layers of a single-sided board without using solder joints. This can significantly reduce the size of a multilayer circuit board.
Compared to traditional PCBs, HDI boards are thinner and smaller, and they provide improved electrical performance. They are also better suited for harsh environments and can withstand higher temperatures. In addition, the shorter distance between devices and trace spaces allow for more components to be deployed on a single board, which can lead to greater device efficiency and lower power consumption.
To get the most out of your HDI PCB, you’ll need a PCB design system built for high-density routing and fine pitch components. Altium Designer is the world’s most trusted PCB design system, with a full suite of CAD tools that support HDI layout and routing.