The Thousand Layer Cake of the Electronic World: Innovative Decryption of High Layer Circuit Board Technology

AI Introduction

Behind smartphone facial recognition is a "miniature city" that is even denser than Manhattan - a high multi-layer PCB the size of a fingernail, using black technology such as laser drilling and arbitrary layer interconnection to achieve lightning transmission of 0.003nS/mm in a 24 layer three-dimensional network, and even withstand the extreme cold test of Mars -196 ℃.

When you use a smartphone for facial recognition, you may not know that the completion of this process depends on a circuit board area that may not exceed the size of a fingernail. This land, which carries billions of transistor interactions, is performing a more densely packed "architectural miracle" than Manhattan - this is the technological wonder created by modern multi-layer printed circuit boards (PCBs).

1、 From flat roads to three-dimensional transportation: the dimensional revolution of circuit boards

The single panel used in early electronic products was like a rural road, where all "vehicles" (electronic signals) were squeezed onto the same plane. In the 1980s, double-sided panels were upgraded to overpass structures, while modern high multi-layer panels have developed into a three-dimensional transportation network with dozens of layers.

Typical layer structure anatomy (taking 12 layer board as an example):

Top/Bottom Layer: Signal Transmission Layer (equivalent to a ground main road)

Level 3/10: High speed signal layer (similar to elevated expressways)

Layer 4/9: Grounding layer (acting as an electromagnetic shielding wall)

5th/8th floor: Power layer (like an underground power supply network)

Layer 6/7: Core Signal Layer (Confidential Data Transmission Channel)

In the 24 layer board used in Huawei's 5G base stations, this three-dimensional layout reduces signal transmission delay to 0.003n/s/mm, which is nearly 8 times higher than the traditional 6-layer board.

2、 Micro scale architectural art: three major technologies that break through physical limits

1. Laser drilling technology: carving flowers on hair strands

When the number of layers on the circuit board exceeds 8, mechanical drilling can cause glass fiber tearing. Modern ultraviolet laser drilling can achieve a pore size of 25 μ m (human red blood cell diameter is about 8 μ m), with over 5000 micropores arranged within an area of 1 square centimeter.

2. Arbitrary Layer Interconnection (ALIVH): Elevator System for Stereoscopic Cities

The technology developed by Panasonic allows for the establishment of vertical channels between any two layers. Just like setting up a dedicated elevator directly between the 17th and 29th floors of a 30 story building, avoiding signal detours.

3. Ultra low loss dielectric material: signal highway pavement

The RO4835 material from Rogers Corporation has a dielectric loss of only 0.0035 at a frequency of 10GHz, which is equivalent to a signal attenuation of only 0.3% per meter of transmission. This improves performance by nearly 20 times compared to traditional FR-4 materials.

3、 Survival tests in extreme environments

High multilayer boards for spacecraft need to withstand:

● Temperature cycle: 2000 impacts from -196 ℃ (liquid nitrogen) to+125 ℃

Mechanical vibration: 50G acceleration within the frequency range of 20-2000Hz

Cosmic radiation: cumulative ionizing radiation dose of 100krad

The 40 layer board used by NASA on the Mars probe is made of polyimide dielectric and gold wire, which can maintain signal integrity at -120 ℃.

4、 Invisible Industry Gaming

In high-end medical CT equipment, data from 256 rows of detectors requires 128 layers of boards to process. The circuit board used in Siemens' latest CT in Germany achieves 18 layers of wiring within a thickness of 0.5mm, with a copper thickness deviation of no more than ± 3 μ m per layer, which is equivalent to uniformly coating a copper layer of hair thickness on A4 paper.

Future prospects: When PCB meets photonics

The optical PCB in the laboratory has started to convert electrical signals into optical pulses for transmission. The hybrid circuit board showcased by Corning integrates optical waveguides alongside traditional copper wiring, achieving a data transmission rate of over 1Tbps while reducing power consumption by 90%. This may indicate the next dimensional revolution in electronic engineering.

Next creative suggestion:

If specific application cases need to be added, in-depth analysis of the PCB design of iPhone motherboards or Tesla autonomous driving modules can be conducted

2. It can supplement the yield control difficulties in the production of high multi-layer boards (such as interlayer alignment accuracy requirements)

3. For the selection of high-frequency materials, more comparative data on the performance of dielectric materials can be added

I hope this article can meet your educational needs for high multi-layer board technology. If you need to adjust the technical depth or supplement specific domain details, please let me know at any time. Comprehensive Guide to Multi Layer PCB Design: From 6-Layer Board Principle to Jialichuang Efficient Sampling Practice

In the context of increasingly complex electronic products today, single and double-sided boards are no longer able to meet the stringent requirements of high-speed signal transmission, electromagnetic compatibility, and power integrity. Therefore, multi-layer PCB (Printed Circuit Board) technology has emerged and rapidly developed. This article will comprehensively analyze the core technical principles, design specifications, and manufacturing processes of multi-layer PCBs (especially 6-layer PCBs), and share practical experience on how to achieve efficient sampling with the help of professional platforms such as Jialichuang. Whether you are a novice hardware engineer or an experienced user looking to optimize your design, you can gain valuable insights into multi-layer board design and practical implementation solutions from this article.

Multi layer PCB technology foundation and advantages of 6-layer board

A multi-layer PCB is a complex circuit board structure formed by alternately stacking and pressing three or more conductive copper foil layers through insulating materials. Compared with traditional single and double-sided boards, multi-layer boards significantly improve the flexibility and integration of circuit design by increasing wiring space in the Z-axis direction. In high demand application scenarios such as high-speed digital circuits, RF systems, and industrial control equipment, multi-layer PCBs have become an indispensable basic carrier.

As the "gold standard" in multi-layer PCBs, 6-layer boards achieve the best balance between complexity and cost. A typical 6-layer stacked structure includes: Top Layer, GND Layer, Mid Layer 1, Power Layer, Mid Layer 2, and Bottom Layer. This carefully designed stacked configuration gives

the 6-layer board the following outstanding advantages:

Excellent signal integrity: Provides low impedance circuits through dedicated power and ground layers, reducing signal crosstalk and electromagnetic interference (EMI). The 6-layer laminated structure recommended by Jialichuang ensures that each signal layer is adjacent to the inner layer, avoiding the crosstalk problem caused by direct adjacent signal layers.

Optimized power distribution: The independent power supply layer can provide stable voltage distribution and reduce power supply noise, which is particularly important for modern processors and high current devices such as FPGAs.

● Higher wiring density: 6-layer boards have two more wiring layers than 4-layer boards, which can increase wiring density by about 50%, suitable for complex logic design and BGA packaging devices.

Better thermal management: A large copper layer helps to evenly distribute and conduct heat, improving system reliability.

Cost benefit ratio: Compared to PCBs with 8 or more layers, 6-layer PCBs maintain good performance while increasing processing costs by only about 30-50%, making them an ideal choice for most mid to high end applications.

Jiali Creation is a leading PCB manufacturer in China, providing full process support from design to production for 6-layer boards, including free disk hole (resin plug hole+electroplated cap) technology, which can significantly improve the throughput and yield of high-density designs. This advanced technology shortens the traditional design cycle from 7 days to around 2 days, saving engineers valuable time.

Core Design Specification for 6-layer Plate and Jialichuang Process Requirements

Successfully designing a high-performance 6-layer board requires adherence to a series of strict regulatory requirements, while fully considering the manufacturer's process capabilities. Jiali Creation is a professional PCB manufacturer with a complete set of process standards and design recommendations for 6-layer boards.

Stacked structure design

A reasonable stacked structure is the cornerstone of 6-layer board design. The standard stacking configuration of 1.6mm thick 6-layer board recommended by Jialichuang is:

1. Top Layer: mainly used to place components and a small number of critical signal lines

2. GND Layer: Provides signal reference plane and electromagnetic shielding

3. Mid Layer 1: Install regular signal lines

4. Power Layer: Allocate various power voltages

5. Mid Layer 2: Install regular signal lines

6. Bottom Layer: Place components and a small number of critical signal lines

This symmetrical structure of "signal ground signal power signal ground" ensures tight coupling between the power source and the ground layer, while each signal layer has adjacent reference planes to minimize crosstalk. Jialichuang specifically pointed out that high-speed signal lines should be prioritized on signal layer 2, so that they can be effectively shielded by the geological and power layers.

Key design parameters

According to the process capability announced by Jialichuang, special attention should be paid to the following parameter limitations when designing 6-layer boards:

Minimum line width/spacing: Inner layer of 6-layer board 3.5mil (about 0.09mm), outer layer 5mil (about 0.127mm)

● Through hole specifications: The minimum hole diameter for mechanical drilling is 0.2mm, and the recommended hole diameter is ≥ 0.3mm; the single-sided through-hole welding ring is ≥ 3mil

Copper thickness selection: The outer layer comes standard with 1oz (35 μ m) and can be upgraded to 2oz; the inner layer is fixed at 0.5oz (17 μ m)

Thickness tolerance: A deviation of ± 10% (1.44-1.76mm) is allowed for a 1.6mm thickness plate

Character specifications: Character line width ≥ 6mil, height ≥ 32mil, ensuring clarity and recognizability

It is worth noting that Jialichuang defaults to using the immersion gold process for 6-layer and above boards instead of tin spraying, because the immersion gold surface is smoother and has better conductivity, which can effectively avoid virtual soldering problems during BGA soldering.

Power and ground handling

The design of the power and ground systems directly affects the performance and stability of the 6-layer board. Jialichuang technical experts suggest:

1. Power ground width: Following the principle of ground wire>power line>signal line, the typical power line width is 1.2-2.5mm

2. Decoupling capacitor layout: Place decoupling capacitors with appropriate capacitance values near the power pins

3. Ground plane integrity: Try to avoid dividing the ground plane as much as possible, and if necessary, use "island" technology for processing

4. Digital analog common ground: The ground of digital circuits and analog circuits should be connected at one point, usually at the power interface

Jialichuang's multi-layer board impedance control service cannot be ignored, as it ensures that the characteristic impedance of high-speed signal lines (such as 50 Ω single ended or 100 Ω differential) meets design requirements without additional costs.

6-layer board wiring strategy and Jialichuang design optimization

Excellent wiring strategy is the key to ensuring the performance of 6-layer boards. Unlike single and double-sided boards, multi-layer board wiring requires consideration of the signal path and electromagnetic field distribution in three-dimensional space. Based on extensive production experience, Jialichuang has summarized the following efficient wiring methods.

Basic principles of wiring

1. Priority for key signals: Sensitive signals such as clock and high-speed differential should be wired first, with short lines as much as possible and reference to the complete plane

2. Orthogonal interlayer direction: The routing directions of adjacent signal layers should be perpendicular to each other (such as horizontal routing on one layer and vertical routing on adjacent layers) to reduce crosstalk

3. Avoid parallel long lines: Avoid parallel wiring between the input and output edges, and if necessary, add a ground wire for isolation

4. 3W principle: The line spacing should be at least 3 times the line width to significantly reduce crosstalk

5.20H principle: The power layer is reduced by 20 times the thickness of the medium compared to the formation, reducing edge radiation

Jialichuang's disk hole technology is particularly suitable for high-density 6-layer board designs. It allows direct drilling on the solder pads without affecting the soldering quality, saving more than 30% of wiring space.

Through hole optimization strategy

Vias are bridges that connect different layers, but they can also become bottlenecks for signal integrity. In the design of 6-layer boards, the following should be considered:

● Prioritize the use of first-order vias: such as connections between layers 1-2, 3-4, 5-6, to avoid complex second-order vias (such as 1-3, 2-5, etc.)

Grounding through holes are commonly used: 1-6 layers of through holes provide better grounding effect

● Control the number of through holes: Too many through holes will reduce the yield rate. Jiali Creation recommends not exceeding 15 through holes per square centimeter

● Pay attention to the size of the welding ring: Jialichuang requires that the single-sided welding ring of the through-hole be ≥ 3mil, otherwise it may cause an open circuit

Special signal processing

High speed digital signals, RF signals, and analog signals require special attention to:

Differential pair: Maintain line length matching and consistent spacing to avoid unnecessary through holes

● Clock signal: Use ground wire shielding and keep away from other sensitive circuits

RF signal: 50 Ω impedance control, try to minimize losses by walking on the surface as much as possible

● Analog signal: far away from digital circuits, using star shaped grounding

Jialichuang's impedance calculation tool can help engineers quickly determine the appropriate combination of linewidth and dielectric thickness to achieve the target impedance.

Jialichuang 6-layer board sampling process and advantages

Translating design into physical objects is a crucial step in PCB development. Jiali Creation is a leading one-stop electronic industry service platform, providing efficient and convenient solutions for 6-layer board sampling.

The entire process of sampling

1. Design submission: The system automatically performs DFM (Design for Manufacturing) checks through Jialichuang EDA or uploading Gerber files

2. Engineering review: Jialichuang engineers verify whether the design meets the process requirements, such as line width, line spacing, aperture size, etc

3. Production and manufacturing: Using high-precision equipment for more than 20 processes such as graphic transfer, lamination, drilling, and electroplating

4. Quality inspection: including flying pin testing, impedance testing (if necessary), and visual inspection

5. Logistics delivery: Shipping from multiple warehouses nationwide, usually with a 6-layer board sampling cycle of 3-5 working days