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The 8-layer PCB laminated structure usually includes signal layer, power layer and ground layer, the specific arrangement and design principles are as follows

Signal layer: It usually includes the top layer (TOP), the bottom layer (Bottom) and the signal layer in the middle (e.g. Signal2, Signal3, etc.). The signal layer is mainly used for wiring and transmitting electrical signals.

Power Layer: It usually includes one or more power layers (e.g. Power1, Power2, etc.), which are used to provide a stable power supply. The power supply layer is adjacent to the ground layer to better realize the coupling between the power supply and the ground, and to reduce the impedance between the power plane and the ground plane.

Ground layer: includes one or more ground layers (e.g. Ground1, Ground2, etc.), which are mainly used to provide a stable ground reference plane and reduce electromagnetic interference. The ground plane is adjacent to the power plane to provide better signal integrity.

Design Principles and Common Arrangements

The layer adjacent to the main chip is the ground plane: it provides a stable reference plane for the main chip and reduces interference.
All signal layers are adjacent to the ground plane as much as possible: provides better signal integrity.
Avoid two signal layers directly adjacent to each other as much as possible: reduce signal interference.
Main power supply is adjacent to its corresponding ground plane as much as possible: to reduce the impedance between the power plane and the ground plane.
Symmetrical structure design: Dielectric layer thickness and type, copper foil thickness, and graphic distribution type should be symmetrical to minimize the impact of asymmetry.

Common design examples and tool usage

Common stacked layer design: such as TOP-Gnd-Signal-Power-Gnd-Signal-Gnd-Bottom, etc. This design can provide better signal integrity and electromagnetic compatibility.
Using Huaqiu DFM tool: This tool helps to calculate impedance, select proper line width and spacing, and ensure the accuracy of the design.

8-Layer PCB Stackup Design Analysis

Option 1: Six Signal Layer Design (Not Recommended)

Structure Characteristics:

1. Top Layer: Signal 1 (Component side/Microstrip routing layer)
2. Inner Layer: Signal 2 (X-direction microstrip, premium routing layer)
3. Inner Layer: Ground (Ground plane)
4. Inner Layer: Signal 3 (Y-direction stripline, premium routing layer)
5. Inner Layer: Signal 4 (Stripline routing layer)
6. Inner Layer: Power (Power plane)
7. Inner Layer: Signal 5 (Microstrip routing layer)
8. Bottom Layer: Signal 6 (Microstrip routing layer)

Drawback Analysis:

• Poor electromagnetic absorption
• High power impedance
• Incomplete signal return paths
• Inferior EMI performance

Option 2: Four Signal Layer Design (Recommended)

Improved Features:

1. Top Layer: Signal 1 (Component side/Microstrip, premium routing layer)
2. Inner Layer: Ground (Low-impedance ground plane, excellent EM absorption)
3. Inner Layer: Signal 2 (Stripline, premium routing layer)
4. Inner Layer: Power (Power plane forming capacitive coupling with adjacent ground)
5. Inner Layer: Ground (Ground plane)
6. Inner Layer: Signal 3 (Stripline, premium routing layer)
7. Inner Layer: Power (Power plane)
8. Bottom Layer: Signal 4 (Microstrip, premium routing layer)

Advantages:
✓ Dedicated reference plane for each signal layer
✓ Precise impedance control (±10%)
✓ Reduced crosstalk (orthogonal routing between adjacent layers)
✓ 40% improvement in power integrity

Option 3: Optimal Four Signal Layer Design (Highly Recommended)

Golden Rule Structure:

1. Top Layer: Signal 1 (Component side/Microstrip)
2. Inner Layer: Ground (Solid ground plane)
3. Inner Layer: Signal 2 (Stripline)
4. Inner Layer: Power (Power plane)
5. Inner Layer: Ground (Core ground plane)
6. Inner Layer: Signal 3 (Stripline)
7. Inner Layer: Ground (Shielding ground plane)
8. Bottom Layer: Signal 4 (Microstrip)

Outstanding Performance:
★ Five ground planes provide perfect EM shielding
★ <3mil power-ground spacing for optimal decoupling
★ Symmetrical layer distribution prevents warpage
★ Supports 20Gbps high-speed signaling

Design Recommendations:

1. Route critical signals on S2/S3 stripline layers first
2. Implement split power plane design
3. Limit top/bottom layer traces to <5mm length
4. Maintain orthogonal routing between adjacent signal layers

Stackup Thickness Reference

Note: All designs should incorporate blind/buried vias for optimal routing space utilization.

Classification and Applications of Printed Circuit Boards (PCBs)

Printed circuit boards (PCBs), as the core components of electronic devices, can be systematically classified based on different characteristics and application scenarios as follows:

Classification by Conductive Layer Count

1. Single-Sided PCB
   The most basic type of PCB, featuring a single copper layer with components mounted on one side and conductive traces on the other. It is simple in structure and low-cost, primarily used in early electronics and simple circuit designs.
2. Double-Sided PCB
   Utilizes copper layers on both sides, with electrical connections between layers achieved through plated through-holes (PTHs). Compared to single-sided PCBs, they offer higher wiring density and design flexibility, making them the most widely used PCB type today.
3. Multilayer PCB
   Consists of three or more conductive layers, bonded together with insulating dielectric materials and interconnected through vias. Multilayer PCBs enable complex circuit designs, meeting the high integration demands of modern electronics.

Classification by Substrate Material

• Rigid PCB
  Manufactured using inflexible, sturdy base materials, including:

• FR-4 (fiberglass epoxy)
• Paper-based substrates
• Composite substrates
• Ceramic substrates
• Metal-core substrates
• Thermoplastic substrates
  Widely used in computers, communication equipment, industrial controls, and more.

• Flexible PCB
  Made with bendable insulating substrates, allowing for folding, rolling, and bending. Ideal for portable electronics such as smartphones and tablets.
• Rigid-Flex PCB
  Combines rigid and flexible sections, providing structural support while allowing bending, making them suitable for 3D assembly applications.

Specialized Functional PCBs

• Metal-Core PCB (MCPCB)
  Composed of a metal base, insulating layer, and circuit layer, offering superior heat dissipation. Mainly used in high-heat applications like LED displays/lighting and automotive electronics.
• Heavy Copper PCB (≥3 oz copper thickness)
  Features:

• High current/voltage handling
• Excellent thermal performance
• Demanding manufacturing processes
  Applications: Industrial power supplies, medical equipment, military electronics, etc.

• High-Frequency PCB
  Characteristics:

• Low dielectric constant materials
• Strict signal integrity requirements
• High-precision fabrication
  Applications: Communication base stations, satellite systems, radar, etc.

• High-Speed PCB
  Features:

• Low-loss dielectric materials
• Precise impedance control
• Minimal insertion loss
  Applications: Networking equipment, servers, data storage systems, etc.

Advanced Multilayer PCB Technologies

• HDI (High-Density Interconnect) PCB
  Technical Features:

• Microvia technology (laser drilling)
• Sequential lamination
• Ultra-high wiring density
  Applications: Smartphones, automotive electronics, aerospace, etc.

• IC Substrate PCB
  Functional Features:

• Direct chip mounting
• High pin-count design
• Miniaturized packaging
  Applications: Memory chips, processors, sensors, and other semiconductor devices.

With advancements in electronics, PCBs continue to evolve toward higher layer counts, greater precision, and increased density. Emerging PCB technologies are driving innovation in electronic product development.

With rising global environmental consciousness, the PCB industry is embracing a profound shift toward sustainability. Stringent regulations and evolving market demands are accelerating the adoption of eco-friendly practices, making green manufacturing an irreversible trend in printed circuit board production.

Sustainable Materials Redefining Industry Standards

• Halogen-free substrates: Enhancing product reliability while reducing environmental impact
• Non-toxic chemical alternatives: Minimizing hazardous emissions
• Energy-efficient production equipment: Cutting power consumption by up to 30%

Eco-Conscious Manufacturing Processes

• Closed-loop water treatment: Reducing wastewater discharge by 40-50%
• Waste recycling systems: Achieving >90% material recovery rates
• AI-driven smart manufacturing: Optimizing material usage and minimizing scrap

Market Forces Accelerating Green Innovation

• 15-20% annual growth in demand for sustainable PCBs
• Eco-certifications (e.g., UL Ecologo, IPC-1401) becoming key purchasing criteria
• Major OEMs prioritizing carbon-neutral PCB suppliers

Policy & Industry Collaboration

• Government incentives for renewable energy adoption
• IPC & IEC developing unified sustainability standards
• Cross-industry alliances sharing breakthroughs in green tech

The Road Ahead: Next-Gen Sustainable Solutions

• Biodegradable substrate R&D gaining momentum
• Zero-liquid-discharge (ZLD) systems nearing commercialization
• Blockchain-enabled carbon tracking emerging as industry norm

Market Projections & Outlook:
The global sustainable PCB market is forecast to surpass $20B by 2025, with CAGR of 18% (2022-2030). While cost and technical hurdles remain, forward-thinking manufacturers are leveraging circular economy principles and digital transformation to establish competitive advantages.

Conclusion: The PCB industry’s green transition represents both a regulatory necessity and a strategic opportunity. Companies investing in clean technologies and transparent sustainability reporting will lead the next era of electronics manufacturing.

Resistors are one of the most fundamental and essential components in electronic circuits, serving multiple critical roles such as current limiting, voltage division, current splitting, energy conversion, and signal processing. This article provides a detailed breakdown of the core functions of resistors, helping engineers, electronics enthusiasts, and industry professionals better understand and apply this component.

1. Current Limiting

Resistors restrict the flow of electric current, protecting sensitive components from damage due to excessive current. According to Ohm’s Law (V = IR), adjusting the resistance value (R) allows precise control over the current (I). For example, a resistor in series with an LED prevents excessive current that could burn out the LED.

2. Voltage Division & Current Splitting

• Voltage Division: In a series circuit, resistors divide the input voltage proportionally. For instance, two resistors in series distribute voltage based on their resistance ratios, commonly used in sensor signal conditioning and voltage reference circuits.
• Current Splitting: In parallel circuits, resistors distribute total current across different branches, ensuring each component receives the appropriate operating current for improved stability.

3. Energy Conversion & Power Dissipation

Resistors convert electrical energy into heat (Joule’s Law, P = I²R), making them useful in heating devices like electric water heaters and stoves. They also act as “load” components, absorbing excess energy to prevent circuit overload.

4. Signal Processing & Conditioning

• AC/DC Signal Handling: Resistors are frequency-independent, making them suitable for signal attenuation, impedance matching, and filtering.
• Specialized Resistors: Components like thermistors (temperature-sensitive) and varistors (voltage-sensitive) are used in sensors, protection circuits, and automated control systems.

5. Circuit Protection & Stability Enhancement

Resistors help suppress inrush currents, improving circuit stability. For example, a series resistor at a power supply input reduces transient current spikes, protecting downstream components.

Conclusion

As a cornerstone of electronic design, resistors are indispensable for current regulation, voltage distribution, signal processing, and circuit protection. When selecting a resistor, factors like resistance value, power rating, tolerance, and type (fixed, variable, or specialized resistors) must be considered to meet specific application needs.

1. Whether the shell of the power capacitor is intact, there is no obvious expansion, deformation, cracks and other phenomena. If the above situation occurs, it means that the capacitor is in serious trouble, i.e., it can not continue to be used.
2. whether the terminals of the capacitor are firmly connected, whether there is any looseness, corrosion and other problems. If there are problems with the terminals, it may lead to poor contact and affect the normal operation of the capacitor.

Second, capacity test

Measure the capacity of the power capacitor to see whether the actual capacity of the capacitor should match the nominal capacity. If the actual capacity is too much lower than the nominal capacity, it means that the capacitor has aged and failed.

Insulation resistance test

Measure the insulation resistance of the capacitor with relevant instruments. Under normal circumstances, the insulation resistance should be greater than 10 megohms. If the insulation resistance is lower than this value, it means that the insulation performance of the capacitor may have been damaged, and further inspection is required.

IV. Voltage and current test

1. Measure the voltage value of the power capacitor during operation. If the voltage value fluctuates greatly, it means that the power capacitor may have problems.
2. Measure the current value of the capacitor under the rated voltage. If the actual current value exceeds the current value, the guidelines indicate that the capacitor may be overloaded.

TEMPERATURE TEST

Detect whether the operating temperature of the power capacitor is within the specified range, under normal circumstances the capacitor should be operated under suitable temperature conditions. If the temperature is too high, it proves that the capacitor may have some kind of failure, need to stop using immediately.
Above is to determine whether the power capacitor failure method. In actual operation, power capacitors should be regularly inspected, if abnormalities are found in a timely manner out of operation, to avoid triggering safety hazards.

The specific methods to test the capacitor are as follows

Method 1: Multimeter Test

We can use a digital multimeter to perform the test. In resistance mode, follow these steps: make sure the capacitor is fully discharged, set the meter to ohm range (at least 1000 ohms), connect the multimeter probe to the capacitor terminals and observe the value displayed by the digital multimeter. The value will then immediately return to the OL (open line) or infinity state. If each attempt shows the same result, the capacitor is good; otherwise, it may be faulty.

Method 2: Analog Multimeter Test

An analog multimeter can also be used to check the capacitance. In ohms mode, do the following: make sure the capacitor is discharged, select resistance mode and connect the multimeter leads to the capacitor terminals. Note the value read and compare it to the standard result. A shorted capacitor will show a low resistance and an open capacitor will not deflect on the ohmmeter. A good capacitor, on the other hand, will show a low resistance at the beginning and then gradually increase to infinity, indicating that the capacitor is in good condition.

Method 3: Checking Capacitance with a Multimeter in Capacitance Mode

Testing in capacitance mode is only possible if the analog or digital multimeter has a capacitance “C” function. In addition, the multimeter’s capacitance mode function is also suitable for testing small capacitance. Observe the reading displayed by the multimeter. If the reading is close to the actual value of the capacitor (i.e., the value printed on the capacitor case), the capacitor is in good condition. Note that the reading may be slightly less than the actual rating of the capacitor, which is usually within the range of ±10 or ±20. If the multimeter shows a reading significantly lower than expected or zero, this may mean that the capacitor is damaged and replacement is recommended to ensure proper operation of the circuit.

Method 4: Testing with a Voltmeter

Test with a voltmeter. This method is equally applicable to both polarized and non-polarized capacitors, but only if we know the nominal voltage value of the capacitor. This voltage level is usually clearly marked on the nameplate of the electrolytic capacitor. Observe the initial voltage reading in the voltmeter. If the reading is close to the supply voltage, the capacitor is in good condition; if the reading is significantly lower, the capacitor may have failed.

Method 5: Testing Capacitance by Measuring Time Constant

If the capacitance value of a capacitor (printed on it in microfarads) is known and the capacitor does not show any abnormalities such as fusing or burning, we can further verify the capacitance value by measuring the time constant. The time constant, usually denoted as τ or Tau, is the time it takes for a capacitor to charge to approximately 2% of the supply voltage, starting from a voltage of 0 during the charging process. This time constant can be calculated by the following formula: τ = R x C, where R is the known resistance value and C is the capacitance value to be measured. Calculate the capacitance value by using the time constant formula. Compare the calculated capacitance value with the value printed on the capacitor. If they are similar or equal, the capacitor is in good condition; if there is a significant difference, it may be necessary to consider replacing the capacitor as it may be operating abnormally. .

Surface-mount (SMD) and crimped components offer excellent manufacturability.

With advancements in component packaging, most parts are now available in reflow-compatible formats—including through-hole components compatible with reflow soldering. A fully surface-mounted design significantly enhances assembly efficiency and quality.

Crimped components, primarily multi-pin connectors, also provide strong manufacturability and connection reliability, making them a preferred choice.

A shorter process path improves production efficiency and quality reliability. The recommended process hierarchy is:

• Single-sided reflow soldering
• Double-sided reflow soldering
• Double-sided reflow + wave soldering
• Double-sided reflow + selective wave soldering
• Double-sided reflow + manual soldering

Component placement should consider orientation and spacing to meet soldering requirements. A well-planned layout reduces defective solder joints, minimizes tooling dependencies, and optimizes stencil design.

The pad geometry, solder mask openings, and stencil fenestration determine solder paste volume and joint formation. Aligning these elements improves first-pass yield in soldering.

“New” packages refer to those unfamiliar to your production team—not necessarily the latest on the market. Before full adoption, conduct small-batch process validation to understand their characteristics, failure modes, and mitigation strategies.

BGAs, chip capacitors, and crystal oscillators are highly sensitive to mechanical stress. Avoid placing them near PCB areas prone to bending during soldering, handling, or operation.

DFM guidelines evolve from real-world production data. Continuously analyze assembly defects and failures to optimize design rules for better manufacturability.