Due to their capacity to handle high-speed, high-performance devices in a compact form factor, HDI (High-Density Interconnect) PCBs are growing in popularity in electronics. Consequently, there is an increasing demand for HDI PCB Design Standards, and engineers must adhere to particular guidelines to ensure their boards perform optimally.
Thus, developing an HDI PCB needs a thorough assessment of multiple facets, including the multitude of layers, vias, pad diameters, trace lengths, and distance among pieces.
In the following paragraphs, we’ll summarize some practical, tried-and-true methods engineers can use for quality. These are essential parameters to generate quality and certain HDI PCBs to satisfy cost considerations, dimensions, and functionality demands.
What is High-Density Interconnect (HDI) PCB?
In a nutshell, HDI (High-Density Interconnect) PCB is a form of PCB that employs sophisticated technology to handle a high density of pieces in a compact area. This is accomplished by including cutting-edge elements like microvias and hidden vias, which permit more links among sections without taking up extra room.
In contrast to conventional PCBs, which use through-hole vias, HDI PCBs use microvias, which are substantially smaller and offer more design freedom. Typically, microvias have a width of fewer than 0.2 millimeters and can be pierced with beams of light, allowing for greater precision and accuracy.
On the contrary, buried vias, or those positioned between sections of the PCB, can also be included in HDI Boards. As a result, fewer through-hole vias are needed. Further links between levels are only possible by growing the design’s size and intricacy.
HDI Boards can include cutting-edge features like blind vias, which link an exterior layer of the PCB to an interior layer without going through the complete board, in addition to microvias and hidden vias. As a result, fewer layers are needed for a particular design, and the layout has more freedom.
In terms of usage, HDI Boards are often employed in strong-performance programs, including laptops, mobile devices, and other electrical devices that require superior performance in a compact design. HDI PCBs can support a substantial component density while keeping signal integrity and minimizing noise by utilizing cutting-edge design elements like microvias, hidden vias, and blind vias.
Features of an HDI PCB
A High-Density Interconnect (HDI) PCB is made to fit many components into a compact area. Thus, we have compiled all of the technical characteristics one must be aware of in an HDI Board; listed below are a few features that set HDI PCBs apart.
Number of Layers
|4 to 22 layers standard, 30 layers advanced|
Compared to typical multilayer boards, these boards have an enhanced attachment pad density, thinner lines, gaps, tiny via openings, and capture pads that enable microvias to only pass-through particular layers and be positioned in surface areas.
|We have the 1+N+1, then the 2+N+2, and then the 3+N+3, and 4+N+4, any layer in R&D.|
FR4 standard, FR4 high performance, Halogen free FR4, Rogers
Copper Weights (finished)
|18μm to 70μm|
|Minimum Track and Gap|
|0.40mm to 3.20mm|
610mm by 450mm; dependent upon laser drilling machine
OSP, ENIG, Immersion tin, Immersion silver, Electrolytic gold, gold fingers
Minimum Mechanical Drill
|Minimum Laser Drill|
0.10mm standard, 0.075mm advanced
Fundamental HDI PCB Design Guidelines
Suppose one wants to ensure that an HDI (High-Density Interconnect) PCB performs at its best. In that case, a few basic design principles must be observed. The essential rules to think about are listed below.
Check the Skills of the Maker Periodically
It’s crucial to regularly assess the manufacturer’s abilities in High-Density Interconnect (HDI) PCB design to ensure they are up-to-date with the most current methods and technologies. Listed below are some strategies for evaluating a maker’s aptitude for HDI Boards Layout:
- Review their Design Portfolio: If one wants to find out if the manufacturer has any expertise with HDI PCB design, look at their design catalog. Seek patterns using microvias, delicate pitch components, and many layers.
- Inquire about their Capabilities: Ask the producer to describe their grasp of HDI technology and how PCB design can use it. Their understanding of various microvia varieties, layered vias, and blind/buried vias might fall under this category.
- EDA Tools Capacity: Ask the manufacturer if they have any expertise with Electrical Design Automation (EDA) software, like Altium Designer, Cadence Allegro, or Mentor Graphics PADS. They should be acquainted with instruments explicitly made for HDI PCB design, like Allegro HDI, which offers microvia streamlining and stack-up organizing functions.
- Provide Training Opportunities: Verify if the fabricator offers educational chances to aid in developing new skills or the enhancement of current ones to their staff. This might entail instruction in particular EDA tools or HDI design methods.
- Conduct a Design Review: Conduct a thorough design evaluation of the supplier’s HDI PCB design abilities. This could entail an assessment of their design data or an actual examination of a sample board.
In general, frequently evaluating a maker’s abilities in HDI PCB design can guarantee that they have the skills and understanding to produce PCBs of the highest caliber and effectiveness.
Observe the Distances Between the Lines and the Electrodes
The only thing that has altered is expanding to microvia levels in 1 mm diameter BGAs. Otherwise, the concept remains identical. The trace breadth is usually similar dimension as the solder shield gap figures. The pad spacing and pad dimensions affect the solder cover space.
Use ELIC and Split Vias Only When Required
Given as much room as feasible for tracking on the topmost and interior levels, HDI routing is the whole purpose. Even though building throughout the complete base might be alluring, only do so if it is essential.
Select Lesser Layers
HDI PCBs with a substantial sheet quantity require more construction stages and production expenses. The expense per board can be significantly decreased if you stick to the preceding recommendation.
When Dealing with HDI devices, Keep Transmission Fidelity in Mind
When dealing with an RF surface, high-frequency design principles should be kept at the forefront when creating any HDI arrangement. In HDI PCBs, amplification differs from standard PCBs in terms of the reliability of signal standards. One must carefully plan your line and stack them up in an HDI board that needs resistance-regulated signaling to ensure the impedance aligns with the communication specification.
HDI PCB Manufacturing and Designing Process
In a nutshell, High-Density Interconnects (HDI) PCBs are complex with high component density and fine traces, making them ideal for small, high-performance devices.
Here are the steps involved in the HDI PCB manufacturing and designing process:
- Define the Design Requirements: Define the design requirements for the HDI PCB, including the board size, layer count, minimum trace width and spacing, and other specifications.
- Schematic Design: Create a schematic of the HDI PCB design using an Electronic Design Automation (EDA) tool, such as Altium Designer, Cadence Allegro, or Mentor Graphics PADS.
- Layout Design: Use the EDA tool to create the layout of the HDI PCB design, including the placement of components, vias, and traces. The structure must follow design rules to ensure manufacturability.
- Review and Revise: Conduct a design review to ensure that the layout meets the design requirements and that the minimum spacing requirements are followed. Make revisions as necessary.
- Generate Manufacturing Files: Generate the manufacturing files, including the Gerber files, drill files, and assembly drawings, to send to the PCB fabricator.
- PCB Fabrication: The fabricator uses the manufacturing files to produce the HDI PCB. This involves layer alignment, imaging, etching, plating, and drilling.
- Assembly: The HDI PCB is then assembled with components using automated surface-mount technology (SMT) or manual placement and soldering.
- Testing: The completed HDI PCB is then tested for functionality and performance to ensure it meets the design requirements.
The HDI PCB manufacturing and designing process requires specialized expertise and equipment. By following these steps and working with experienced professionals, designers can create high-quality HDI PCBs that meet their applications’ performance and functionality requirements.
Benefits of HDI PCB
High-Density Interconnect (HDI) PCBs offer several benefits compared to traditional PCBs, making them a popular choice in modern electronic devices.
Indispensable advantages of HDI PCBs include the following:
- Increased Component Density: HDI PCBs allow for much greater component density, allowing more functionality to be packed into smaller devices. This makes HDI PCBs ideal for mobile phones, tablets, and other small electronic devices.
- Smaller Size: With higher component density, HDI PCBs can be made smaller, reducing the overall size and weight of electronic devices.
- Improved Signal Integrity: The shorter, more direct signal paths of HDI PCBs can reduce signal loss and noise, leading to enhanced signal integrity.
- Faster Signal Transmission: The reduced distance between components on an HDI PCB can improve signal transmission times, leading to faster performance.
- Increased Reliability: HDI PCBs use advanced manufacturing techniques that result in more reliable boards, reducing the risk of failure and improving overall product quality.
- Lower Cost: While the initial cost of designing and manufacturing HDI PCBs may be higher than traditional PCBs, the increased reliability and reduced size can lead to overall cost savings in the long run.
Overall, HDI PCBs offer many benefits that make them popular in modern electronic devices. By increasing component density, reducing size, improving signal integrity and transmission, increasing reliability, and potentially lowering costs, HDI PCBs are a critical enabling technology for a wide range of electronic devices.
Applications of HDI PCB
High-density interconnect (HDI) PCBs are used in many applications where space and performance are critical.
A few of the most typical uses for HDI PCBs are listed below:
- Mobile Devices: HDI PCBs are ideal for mobile phones, tablets, and other portable electronic devices due to their high component density and small size.
- Automotive: HDI PCBs are used in automotive applications with limited space, such as in-car entertainment systems, GPS systems, and engine control units.
- Medical Devices: HDI PCBs are used in medical devices such as diagnostic equipment, patient monitoring systems, and implantable devices due to their high reliability and small size.
- Aerospace and Defense: In military and security uses where pounds and dimensions are crucial considerations, HDI PCBs are employed. They are used in avionics systems, satellite communications, and military equipment.
- Consumer Electronics: HDI PCBs are used in various consumer electronics, including cameras, smart watches, gaming consoles, and virtual reality devices.
- Industrial Equipment: HDI PCBs are used in industrial equipment such as automation, robotics, and machine control systems.
Apart from the mentioned industries, the HDI PCBs are prevalent in 5G and AI Smart Technologies, wherein swift data communications are necessary.
In general, the high component density and small size of HDI PCBs make them ideal for use in a wide range of applications where space and performance are critical. By enabling more functionality to be packed into smaller devices, HDI PCBs are a necessary enabling technology for developing modern electronics.
In summary, in this article, we have proven the importance of determining the design guidelines for HDI PCB since they significantly affect the overall quality and performance of the board during operation. Consequently, we have tackled the various approaches to keep in mind whenever dealing with HDI PCBs.
Suppose you need to be more confident in layout and configuring your HDI PCB. In that case, there is no need to worry, as MV Flex Circuit has decades of experience performing this service. We have served and satisfied over a thousand clients worldwide. We’re eager to fulfill more of them by providing our top-tier services and products through our advanced technologies and experienced personnel.
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