High-Density PCB Design Planning
Key Takeaways
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Basically, there are two high-density PCB designs: build-up structure and any-layer structure.
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Type 5 high-density PCBs are a popular construction using layers with no core.
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When redesigning a regular PCB to high-density interconnect technology, budget, manufacturing time, electrical performance, etc. get compromised.
The wiring density per unit area of HDI boards is relatively higher than basic printed circuit boards
The electronics industry is always striving for more miniaturized products. Consumers are more satisfied when device size and weight are reduced. Smaller devices are made possible with high-density interconnect PCB technology. High-density PCB design is entirely different from conventional PCB design, and that is what makes it superior when it comes to dimension, weight, and performance. Let’s discuss high-density PCB design planning in this article.
High-Density PCBs
High-density interconnect technology is growing fast and has revolutionized the PCB industry as well as the electronics market. The wiring density per unit area of HDI boards is relatively higher than basic printed circuit boards. The features of high-density boards, such as lightweight, compactness, cost-effectiveness, etc., are provided by including micro vias, blind and buried vias, sequential laminations, thin lines and spaces, via-in-pad techniques, etc. The electrical performance of the circuits laid on high-density PCBs is enhanced by incorporating via technology and lamination.
Advantages of High-Density PCBs
The advantages of high-density PCBs are numerous. Some advantages include:
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Space |
Availability of space on the board to place more components (both sides). |
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Density |
High wiring density per circuit area. The HDI PCB provides a finer track arrangement. |
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Versatile routing |
Versatile routing and dense packaging are possible with micro vias and via-in-pad technology. |
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Signal integrity |
Better signal integrity and faster transmission. |
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Reduced cost and size |
Integration of all sub-circuits to a single board, thereby reducing overall cost and size. |
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Reliability |
High reliability under extreme environmental conditions due to the incorporation of stacked vias. |
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Easy thermal management |
The thermal management of the board can be improved with small holes drilled using lasers. |
Structure of High-Density PCBs
Basically, there are two high-density PCBs: build-up structure and any-layer structure.
Build-Up Structure
The build-up structure issues the sequential lamination process, and hence it is also called a sequential lamination structure. The sequential lamination or build-up structure is the most common high-density PCB structure. The design flow of the build-up structure is illustrated below.
Any-Layer Board Structure
The any-layer board structure or type 6 high-density boards freely interconnect all the micro vias and are suitable for high-level interconnection applications.
Types of High-Density PCBs
As per the IPC 2226 standard, high-density PCBs can be classified into different types. The table below describes the six types.
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Type |
Description |
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Type 1 |
Plated micro vias and plated through-holes are used for interconnection. Only a single micro via layer is allowed on either one side or both sides of the core. |
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Type 2 |
Possible to incorporate through-hole vias in the core before applying the high-density interconnect layers. The through-hole vias can connect the outer layers from surface to surface. |
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Type 3 |
With the inclusion of a through-hole, two or more high-density interconnect layers can be added on top of the core. In this type of high-density PCB, through-vias from surface to surface are also allowed. |
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Type 4 |
Micro vias act as a redistribution layer over the existing drilled and plated substrate, which is passive with no electrical function. |
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Type 5 |
A popular construction using layers with no core. |
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Type 6 |
The alternative for no core or coreless construction using a layer pair corresponds to type 6 high-density PCBs. |
Proper planning is necessary before choosing the board layout for any of the types given above.
High-Density PCB Design Planning
It is not required to design all the printed circuits as high-density boards. If the high-density interconnect technology is to be applied to the design, then it is best to start it right from the beginning rather than modifying the conventional PCB design. The process of redesigning or modifying into a high-density PCB is an expensive process.
The complexity of high-density PCB boards is greater than standard or traditional PCBs. In this context, it is important to plan ahead for the high-density PCB design process and related considerations.
Benefits of High-Density PCB Design Planning
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Expensive Design Interactions Can Be Avoided
When redesigning a regular PCB to high-density interconnect technology, budget, manufacturing time, and electrical performance get compromised.
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Fast Designing
Proper planning of the high-density PCB design can help you stay within budget limits without curbing any requirements and speed up the design process.
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Optimizing the High-Density PCB Design
A well-planned high-density PCB design process never leaves room for the design to be sub-optimal. The planned approach to the designing of high-density PCBs with the exact number of layers, traces, space sizes, vias, pads, lamination cycles, etc. prevents any confusion.
Cadence OrCAD software helps with high-density PCB design planning when creating, placing, and reusing blind and buried via stacks in high-density PCBs. Leading electronics providers rely on Cadence products to optimize power, space, and energy needs for a wide variety of market applications. If you’re looking to learn more about our innovative solutions, talk to our team of experts or subscribe to our YouTube channel.