6-Layer HDI Circuit Board

Description

A 6-layer 1st-order HDI PCB is a type of multilayer high-density interconnect (HDI) printed circuit board, commonly used in electronic products that require high density, high speed, and high reliability. HDI (High-Density Interconnect) technology uses micro-via, blind via, and buried via techniques to achieve higher circuit density and smaller size, making it suitable for complex and highly integrated circuit designs. A 6-layer 1st-order HDI PCB is one of the applications, consisting of six circuit layers, where “1st-order” indicates the use of a combination of micro-blind vias and micro-vias.
This article provides a detailed introduction to the structure, design principles, manufacturing process, advantages, and application fields of the 6-layer 1st-order HDI PCB.
1. Basic Concept of 6-Layer 1st-Order HDI Circuit Board
The 6-layer 1st-order HDI PCB consists of six layers, including signal layers, power layers, and ground layers. “1st-order” refers to the use of a combination of micro-blind vias (which connect part of the layers) and micro-vias (which go through multiple layers) to interconnect the layers.
Differences Between HDI and Traditional Circuit Board
Higher Circuit Density: HDI boards use narrower traces and smaller hole diameters, allowing more circuit functions to be integrated into the same area, achieving higher density in limited space.
Precise Signal Transmission: HDI technology ensures more stable and efficient signal transmission through more precise designs, reducing electromagnetic interference (EMI) and signal attenuation.
Compact Layout: The use of blind and buried vias optimizes the space usage on the PCB, making the layout more compact.
2. Structure of 6-Layer 1st-Order HDI Circuit Board
A 6-layer 1st-order HDI Circuit Board typically includes the following main layers:
Top Layer: The outermost layer for placing high-frequency signals, power, and grounding.
Inner Layer 1: The first inner signal layer, interconnecting with the top layer via micro vias or blind vias.
Inner Layer 2: The second inner signal layer used for additional routing and signal transmission, typically placed between the power and ground layers.
Power Layer: Dedicated to distributing stable power to other components on the board.
Ground Layer: Ensures proper grounding to minimize EMI and maintain signal integrity, especially for high-frequency signals.
Bottom Layer: Corresponds to the top signal layer and is located at the bottom of the PCB.
For 1st-order HDI, the combination of micro-blind vias and micro-vias ensures precise and high-density interconnections between the different layers, achieving better performance and signal integrity.
3. Manufacturing Process of 6-Layer 1st-Order HDI Circuit Board
The manufacturing process for a 6-layer 1st-order HDI PCB involves several detailed steps to ensure high density, precision, and reliability. Key steps include material selection, lamination, drilling, copper plating, etching, and surface treatment.
Material Selection: HDI PCBs are typically made from high-performance substrates such as FR4 or PTFE to meet the requirements for high-frequency and high-speed signal transmission.
Lamination: Different materials are laminated together at high temperatures and pressures to ensure strong bonding and stable electrical performance between layers.
Drilling and Hole Processing: Laser or mechanical drilling is used to create micro-vias and micro-blind vias for interconnecting layers.
Copper Plating and Coating: Copper is electroplated onto the walls of vias to ensure electrical connections, and a copper layer is applied to the surface.
Chemical Etching: Excess copper is etched away to form the required circuit traces.
Surface Treatment: Surface treatments such as HASL (Hot Air Solder Leveling), ENIG (Electroless Nickel Immersion Gold), or OSP (Organic Solderability Preservative) are applied to ensure excellent solderability.
4. Advantages of 6-Layer 1st-Order HDI Circuit Board
Compared to traditional PCBs, 6-layer 1st-order HDI PCB offer several distinct advantages:
High Circuit Density: By using micro-blind vias and micro-vias, 6-layer 1st-order HDI PCBs enable more signal layers and circuits to be placed in the same area, increasing the board’s density and allowing for more functions.
Better Electrical Performance: With more precise routing, these boards offer superior signal transmission and lower attenuation, especially for high-speed and high-frequency applications.
Compact Size: HDI PCBs allow more functionality in smaller sizes, ideal for space-constrained devices.
Higher Reliability: The precise layout and optimized hole design of HDI PCB enhance their resistance to interference and mechanical stress, providing stable performance even in extreme environments.
Improved EMC: With appropriate power and ground layer designs, these PCB reduce EMI and improve electromagnetic compatibility, ensuring stable performance in high-frequency environments.
5. Applications of 6-Layer 1st-Order HDI Circuit Board
6-layer 1st-order HDI PCB, with their high density, integration, and reliability, are widely used in industries that require high-performance circuit boards.
Telecommunications: In smartphones, base stations, Wi-Fi routers, and other communication devices, 6-layer 1st-order HDI PCB meet the increasing demand for high-density interconnects driven by the development of 5G technology.
Consumer Electronics: Devices like smartwatches, wireless earbuds, tablets, and other consumer electronics rely on HDI PCB to meet the demand for high functionality and compact size.
Automotive Electronics: In the automotive industry, especially in autonomous and electric vehicles, 6-layer 1st-order HDI PCB are used in control units, radar sensors, and infotainment systems.
Medical Devices: These PCB are used in portable monitors, ultrasound systems, and in vitro diagnostic devices, where high signal integrity and reliability are crucial.
Computer Hardware: 6-layer 1st-order HDI PCB are increasingly used in computer hardware such as motherboards, graphics cards, and storage devices, where high-density and fast signal processing are required.
With their high-density, high-speed, high-integration, and high-reliability advantages, 6-layer 1st-order HDI PCBs have become indispensable in many advanced electronic products. As technology continues to evolve, the use of 6-layer 1st-order HDI PCB will keep growing across various industries such as telecommunications, consumer electronics, automotive electronics, medical devices, and more. With the advancements in 5G, IoT, and autonomous driving technologies, the demand for these PCBs will continue to rise.