How to Optimize HDI PCB Design
The PCB industry has evolved dramatically over the past three decades. The recent addition of hybrid circuits (HDI) to PCB design makes it difficult to implement a successful production process without optimization. HDI technology is quickly overtaking conventional design and manufacturing procedures in terms of performance and cost-effectiveness.
If you have ever designed an HDI PCB, then you know how challenging the HDI design can be. The traces may be too wide, the copper pours do not work with the copper plane, or it just does not fit on the board. In this post, we will talk about optimizing your HDI PCB design to get a professional-looking product that will work.
Easy Ways to Optimize HDI PCB Design
1. Select Materials Based on Performance
Traditional materials like FR4 have been used for decades and have proven their worth in countless applications. However, they are not always the best choice for all scenarios. For example, if you are designing something that needs a lot of power handling capability, consider using Rogers’ high-temperature range of materials. These products offer excellent thermal conductivity and can withstand high temperatures without cracking or warping over time. This makes them ideal for use in situations where heat build-up can cause problems, such as electronic enclosures or other areas where other components in the system generate heat.
Check Power Planes
Power planes are located on both sides of the board, and they help distribute power throughout the board. When designing an HDI PCB, it is important to have multiple planes so that you can distribute power more evenly throughout the board. However, when creating a plane on both sides of the board, there needs to be a certain distance between them so that they do not touch each other or short out. If this happens, it will cause problems with your design as well as cause issues during production when testing for shorts and opens on boards at the assembly stage. Make sure there is enough space between these two layers so that they do not touch each other or short out during the assembly stage and testing phase afterward.
Use Multiple Via Types
Different via types have different characteristics; some are better suited for certain applications than others. For example, blind vias are ideal for internal routing in a multilayer board because they do not require plating but require an opening in the copper to be drilled through the board material. Through-hole vias are ideal for surface mount boards because they do not need a plate and can be placed anywhere on the board surface.
Use Ground Planes for Grounding
Ground planes provide a low-impedance path for ground current flow and help minimize the amount of stray capacitance on your board. When you have multiple ground planes at different potentials, you should use vias between them to connect them. This will reduce the risk of crosstalk between separate ground planes and allow you to use only one reference point for ground connections across all planes.
Align Signal Layers with Ground Planes
The primary goal of HDI design is to ensure that all metal traces are electrically isolated. To achieve this, it is important to align signal layers with ground planes on both sides of the board. This will prevent the formation of shorts between traces that cross over each other while ensuring that signals propagate across the entire board without interference or degradation.
Add Solder Masks for an Additional Layer of Heat Protection
Solder masks are critical to the long-term reliability of your board, especially in harsh environments or when used for high-voltage applications. Solder masks protect the copper traces from oxidation and corrosion by preventing moisture or other contaminants from penetrating the board during operation. This is especially important when working with high voltages or performing tests in extreme temperatures — a solder mask can be your best protection.
Increase Trace Width for Long Traces
The most common mistake in HDI PCB design is using too thin trace widths or too many vias, which increases parasitic capacitance and resistance in long traces. To avoid this problem, use 2 oz copper thickness for long traces instead of 1 oz to reduce inductance and capacitance.
Ensure Thermal Reliefs Are Placed Correctly for Maximum Effectiveness
HDI boards have more surface area than traditional boards, so heat is more easily dissipated. However, this also means that you must pay attention to where thermal reliefs are placed when designing your board. If relief is placed in the wrong place, it can cause more problems than it solves.
Thermal reliefs should be placed in areas where they will provide the most benefit. For example, if there is a large heat source near a corner of your board (like an ASIC or FPGA), thermal reliefs should be placed near those corners rather than in the middle of the board. This will help ensure that heat is removed from those areas where it matters most instead of being spread across the entire board.
Increase Via Diameter for Signal Traces
This is another important factor in improving the signal integrity of your HDI PCB. The via diameter should be increased as per the distance between vias and traces on both sides. For example, suppose two vias are 7mm apart from each other. In that case, you need to increase their diameter to at least 2mm by increasing via size in CAM software or manually adding an extra copper area around it. This will help reduce the impedance of signal traces between vias so that they work properly without any issue.
The Bottom Line
All in all, HDI PCB technology is fantastic for prototype boards. And regardless of how you approach the design, there is a lot you can do to narrow your process—and fine-tune it for optimum results.
To get the most effective results, it is important to consider the connections in a balanced and efficient way. In this regard, we hope this blog post has been helpful and given you some great ideas to put into practice when working on PCB design projects in your professional life. If you would like to learn more about the HDI technology, we recommend checking out Hemeixin for a guide on HDI Flex PCB.