Abstract:

With the rapid development of automotive intelligence and networking, on-board electronic systems are becoming increasingly complex, which puts forward higher requirements for the rate, reliability and anti-interference ability of communication transmission. Optical fiber harnesses, with their advantages of high speed, low loss, anti-electromagnetic interference and lightweight, are gradually becoming the ideal choice for in-vehicle communication systems. This article systematically analyzes the technical features, application advantages and implementation plans of optical fiber harnesses, and looks forward to their development prospects, providing a reference for the upgrade of automotive communication systems.

Introduction

At present, functions such as autonomous driving, Internet of Vehicles and high-definition entertainment have driven a sharp increase in the volume of in-vehicle data, posing challenges to traditional copper wire transmission in terms of speed and stability. Optical fiber communication technology, with its outstanding performance, provides an effective solution for building a new generation of vehicle-mounted networks. This article conducts an analysis from the dimensions of technical principles, application scenarios and system solutions, explores the role of optical fiber harnesses in promoting the upgrade of automotive communication, and looks forward to their prospects for large-scale application.

Technical Overview of Optical Fiber Harnesses

Optical fiber harnesses use light waves as the transmission carrier and rely on optical fiber media to achieve signal transmission. Their core advantages lie in high speed, high reliability, low loss and resistance to electromagnetic interference, fully matching the communication requirements of vehicle systems for large data volume and high real-time performance. Its communication link is mainly composed of optical fiber connectors and optical fiber conductors, which work together to ensure the stable transmission of signals.

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1.1 Optical Fiber Connector

Optical fiber connectors are core passive components for achieving active optical fiber connections. They are composed of key structures such as optical fiber reinforcement, alignment, elastic docking, locking, and optical cable fixation (see Figure 1). The core working principle is as follows: Ceramic pins and ceramic sleeves are used to achieve precise alignment of optical fibers. The elastic alignment force is provided by the spring in the pre-compressed state - during the connection, the pins retract to generate secondary compression, ensuring that the two pins are always in a compressed contact state and guaranteeing the stability of the connection. This structural design enables the optical fiber connector to feature reliable insertion and extraction as well as low loss, making it suitable for the usage requirements of vehicle-mounted environments. ​

1.2 Optical Fiber Conductor

Optical fibers have a cylindrical structure and are composed of three layers: the core, the cladding, and the coating (see Figure 2). Their transmission core relies on the principle of total light reflection: when light is incident from the core with a high refractive index (optically dense medium) onto the cladding with a low refractive index (optically sparse medium), if the incident Angle is greater than the critical Angle, all the light will be reflected back to the core, achieving leak-free signal transmission. ​

The core technical features of optical fibers can be summarized in six points:

(1) Outstanding transmission efficiency: Fast transmission speed, long distance, capable of simultaneously carrying massive amounts of data, far exceeding traditional wires; ​

(2) Strong anti-interference ability: It transmits optical signals rather than electrical signals, is not affected by electromagnetic interference, and ensures stable signal quality; ​

(3) Wide frequency band: Supports ultra-high-speed data transmission, meeting the parallel communication requirements of multiple systems in vehicles; ​

(4) Extremely low loss: The theoretical transmission loss can be as low as less than 0.0035 dB per kilometer, achieving long-distance transmission without attenuation. ​

(5) High security: No electromagnetic radiation, not easy to be eavesdropped on, suitable for sensitive data transmission scenarios in vehicles; ​

(6) Lightweight and miniaturization: Compared with copper cables, it is smaller in volume and lighter in weight, facilitating on-board layout and maintenance, and reducing the overall burden on the vehicle.

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The advantages of optical fiber harnesses in the intelligent application of automobiles

When the transmission rate of traditional copper wires reaches over 10 GB/s, the wire diameter needs to be thickened to meet the requirements. This will directly lead to an increase in the overall vehicle weight and cost, which is contrary to the development trend of automotive lightweighting and low cost. While enhancing communication performance, optical fiber harnesses perfectly avoid the aforementioned drawbacks. Their core advantages are specifically reflected in four aspects:

(1) Transmission rate outperforms traditional wires: Optical fiber harnesses can transmit millions of megabytes of data per second, easily meeting the large data volume transmission requirements of autonomous driving, high-definition entertainment, etc. However, the maximum speed of traditional copper wire networks is only 10GB/s, which is difficult to meet the communication upgrade requirements of intelligent vehicles. ​

(2) Extremely low transmission loss: The loss of optical fibers per kilometer is usually less than 0.0035 dB/m, ensuring high-quality signals even during long-distance transmission. The transmission loss of traditional copper wires reaches 0.5 dB/m, and the signal attenuation is severe during long-distance transmission, requiring additional relay equipment. ​

(3) Electromagnetic interference immunity: The light wave transmission characteristics make it immune to electromagnetic interference generated by the vehicle's internal engine, sensors and other electronic devices, and it will not cause interference to other on-board electronic systems, ensuring communication stability and compatibility with the vehicle's electronic systems. ​

(4) Facilitating vehicle lightweighting: Automotive optical fibers represented by plastic optical fibers (POF) are much lighter than traditional metal wires, which can significantly reduce the vehicle's overall weight, improve fuel economy or driving range, and align with the development direction of automotive energy conservation.

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Application scenarios of optical fiber harnesses in Automobiles

Optical fiber harnesses have been widely applied in communication, industry, medical care and other fields, but their implementation in the automotive field still faces challenges such as insufficient basic theories, lack of technical specifications, unclear test standards and limited application practices. Its in-vehicle applications need to focus on adapting to the environmental characteristics of different areas of the car and provide targeted solutions.

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3.1 Application of Optical Fiber Harnesses in the Layout Area

The usage environment of automobiles is complex, and the requirements for the temperature resistance, water resistance and vibration resistance of wiring harnesses vary significantly in different regions. Based on the risk of liquid contact, the vehicle layout area can be divided into three categories, corresponding to different protection levels of the wiring harness:

(1) Wet zone: The area that is bound to come into contact with liquids during regular use, such as the chassis, engine room and other areas outside the passenger cabin. In rainy and snowy weather, the wire harness connectors in this area are prone to contact with rainwater and sewage, and the highest level of waterproof protection is required. ​

(2) Potential wet areas: These are areas that may come into contact with liquids in specific scenarios, such as the floor of the passenger compartment, door handrails, and seat surfaces. They may come into contact with liquids due to opening the door on rainy days, spilling water cups, or dripping condensate water, and require moderate waterproof protection. ​

(3) Absolute dry zone: An area where there is almost no possibility of liquid contact during normal use, such as the interior of the dashboard and the interior of the ceiling, which has the lowest requirements for waterproof sealing. ​

The waterproof sealing requirements of the three aspects decrease successively from the wet area to the dry area, which is the core basis for the layout of the optical fiber harness.

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3.2 Optical Fiber Harness Application Solutions

The application of optical fiber harnesses in vehicles must simultaneously meet the requirements of electrical performance and mechanical performance, with a focus on addressing the three core challenges of temperature, vibration, and waterproofing. The specific solutions are as follows:

(1) Optical fiber cables: Multi-dimensional adaptation to vehicle environments

For high-temperature environments:

① Select high-temperature resistant materials (such as silicone wire, XLPE wire) to ensure stable insulation at high temperatures;

② It adopts a double-layer coating + ultraviolet curing process to enhance high-temperature resistance.

③ Optimize the layout plan to avoid the engine exhaust pipe and high-temperature vortex areas, and use high-temperature resistant heat insulation coatings (such as aluminum foil fiberglass tubes), while enhancing the aging resistance. ​

In response to waterproofing requirements: A multi-layer protective structure design is adopted - the outermost plastic sheath provides basic waterproofing and mechanical protection, the inner metal sheath enhances the pressure resistance and waterproofing capacity, and a water-swelling water-blocking layer is set in the middle (which rapidly expands to close the path when water invades). The optical fiber is wrapped with grease inside the cable core to absorb trace amounts of moisture, ensuring the optical fiber remains dry in all aspects. For instance, the automotive optical harness solution of Yangtze Optical Fibre and Cable Co., Ltd. features quartz multimode fibers that meet automotive standards in terms of bending (radius 10mm), tensile strength (150N), temperature adaptability (-40℃ to 125℃), aging (125℃/3000h), and vibration (V3). ​

(2) Optical fiber connector: Dual upgrades for temperature resistance and water resistance

Enhance temperature resistance:

① Design a heat dissipation structure, reserve metal components for heat conduction, add heat dissipation fins to the casing, and use a metal casing to improve heat dissipation efficiency;

② High-temperature resistant materials are selected. The shell and internal structure are made of high-quality engineering plastics resistant to medium and low temperatures, and key components are made of special alloy materials to enhance high-temperature resistance and anti-deformation capabilities. For instance, the non-contact optical connectors launched by Letas Optics offer higher repeatability in insertion and extraction, longer lifespan, lower insertion loss, and lower dust sensitivity compared to traditional products. ​

Enhanced waterproof performance: Adopt a combination solution of heat shrink tubing and sealant - place the heat shrink tubing over the connection part, heat it to shrink and closely adhere to the joint and optical fiber, then evenly apply sealant to fill the gap. After drying and hardening, it forms a double protection to prevent moisture and contaminants from entering. ​

(3) Hybrid connection scheme

It adopts a "fiber optic + electrical connection" hybrid mode: the fiber optic is responsible for high-speed data transmission, and the electrical connection port is responsible for the power supply function of the sensor, taking into account both transmission efficiency and power supply stability, and meeting the requirements of multi-device collaborative operation in vehicles. 

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Conclusion

The development of intelligent automobiles has put forward requirements for high speed, low loss, anti-interference and lightweight communication systems, which has driven the upgrade of traditional copper wires to optical fiber harnesses. Optical fiber harnesses, with their core advantages such as transmission efficiency, anti-interference ability and lightweight, perfectly match the communication requirements of vehicles. Through implementation measures such as regional protection design, material and process optimization, and hybrid connection schemes, the adaptation to the complex on-board environment has been achieved. ​

In the future, with the improvement of basic theories, the standardization of technical norms, and the accumulation of application practices, optical fiber harnesses will be applied on a large scale in the automotive industry, becoming the communication support for core functions such as autonomous driving and the Internet of Vehicles, injecting key impetus into the intelligent upgrade of automobiles, and leading in-vehicle communication into a new era of high speed, reliability and efficiency.

In today's fast-paced world, staying connected while maintaining your health has never been more important. The T9 Smartwatch beautifully bridges this gap, combining sophisticated design with comprehensive health monitoring in one sleek device. Its 1.27-inch HD display offers crystal-clear visibility, while the lightweight 40-gram design ensures all-day comfort without compromising on style.

What truly sets the T9 apart is its advanced health monitoring system. The watch provides 24/7 heart rate tracking, blood oxygen monitoring, and stress level detection, giving you valuable insights into your wellbeing. For women, it offers specialized health tracking with menstrual cycle reminders and predictions. The built-in breathing training guide helps you manage stress effectively, while intelligent sleep analysis helps optimize your rest patterns.

Beyond health features, the T9 keeps you connected with Bluetooth calling and message notifications. Fitness enthusiasts will appreciate the multiple sports modes that accurately track various activities, and the music control feature adds convenience to your workouts. With its elegant design transitioning seamlessly from day to night, the T9 isn't just a smartwatch - it's your personal health companion that complements your lifestyle while keeping you connected and healthy.

How Does Embedded Copper Coin Technology Enhance Thermal Management in High-Frequency PCBs?

In the demanding world of high-frequency electronics, thermal management is not just a mechanical consideration—it is a critical factor that directly impacts electrical performance, signal integrity, and long-term reliability. As power densities increase in applications like 5G base stations and automotive radar, traditional cooling methods often fall short. This is where embedded copper coin technology emerges as a changing solution, offering a direct and highly efficient path for heat dissipation.

Here’s a detailed breakdown of how this technology enhances thermal management:

1. The Fundamental Principle: Creating a Low-Thermal-Resistance Path

At its core, an embedded copper coin is a solid, thick piece of pure copper that is precision-machined and pressed into a milled cavity within the PCB's substrate during the lamination process. The key to its effectiveness lies in its ability to create a low-thermal-resistance pathway from the heat source to a heat sink or the opposite side of the board.

• Direct Thermal Connection: The coin is placed directly beneath a specific high-power component, such as a Power Amplifier (PA), Field-Programmable Gate Array (FPGA), or processor. This creates an intimate thermal connection, bypassing the insulating layers of the PCB laminate.

• Superior Thermal Conductivity: Copper has a thermal conductivity of approximately 400 W/mK, which is orders of magnitude higher than standard FR-4 (~0.3 W/mK) or evenhigh-frequency materials like M6. This massive disparity means heat is drawn away from the component and into the coin with remarkable efficiency.

2. Superiority Over Traditional Methods

To appreciate the copper coin's advantage, it's helpful to compare it to common alternatives:

• Vs. Thermal Vias: A cluster of thermal vias is a common solution. However, each via is a cylinder plated with a thin layer of copper (e.g., 20µm), filled with air or a thermal epoxy. The effective cross-sectional area of solid copper in a via field is relatively small. A solid copper coin, in contrast, provides a massive, uninterrupted cross-section of pure copper, resulting in significantly lower thermal resistance and much more efficient heat spreading.

• Vs. External Heat Sinks: While effective, top-side heat sinks can be bulky, heavy, and interfere with component placement or airflow. An embedded coin can often reduce the size and weight of an external heat sink or, in some cases, eliminate the need for one altogether, enabling more compact and elegant designs.

3. Direct Benefits for High-Frequency Performance

The thermal benefits of the copper coin translate directly into enhanced electrical performance, which is crucial for high-frequency PCBs:

• Preventing Performance Drift: Many active components, especially RF components, have performance parameters (like gain, output power, and noise figure) that are sensitive to temperature. By maintaining a stable, lower operating temperature (T_j, junction temperature), the copper coin ensures the component performs consistently within its specified range.

• Improving Signal Integrity: Excessive heat can increase the dissipation factor (Df) of the PCB laminate and alter its dielectric constant (Dk). This can lead to signal attenuation, impedance mismatches, and phase shifts. Effective cooling via a copper coin helps maintain the stable electrical properties of the surrounding M6 material or IT-180 material.

• Enabling Higher Power Density: By efficiently managing the "hotspots," designers can safely use more powerful components or pack them more densely on the board without fear of thermal throttling or failure, pushing the boundaries of what's possible in a given form factor.

4. Enhancing Mechanical Reliability and Lifespan

Thermal cycling—the repeated heating and cooling of a board during operation—is a primary cause of failure in electronics.

• Reduced Thermal Stress: By effectively dissipating heat, the copper coin minimizes the peak temperature and the temperature delta across the board and within the component itself. This reduces the mechanical stress on solder joints and the PCB laminate, preventing cracking and delamination.

• Increased Mean Time Between Failures (MTBF): A cornerstone of reliability engineering is that component failure rates decrease exponentially with lower operating temperatures. By keeping critical components cool, the embedded copper coin directly contributes to a longer, more reliable operational lifespan for the entire system.

Implementation in a Hybrid PCB

In a sophisticated board like the Copper Coin Embedded 6-Layer M6 IT180 Hybrid PCB, the coin is strategically placed in the center of the PCB stackup. It connects directly from the component on the outer layer down to the internal ground planes or to the bottom side, where it can be attached to an external chassis or heat spreader. This integration is seamless and is completed during lamination, ensuring a robust mechanical bond and optimal thermal transfer without compromising the board's structural integrity.

Conclusion

Embedded copper coin PCB technology is a powerful and targeted thermal management solution that directly addresses the thermal bottlenecks in high-frequency, high-power PCBs. It moves beyond the limitations of traditional vias and heat sinks by providing a low-resistance, high-conductivity thermal highway. The result is not just a cooler-running board, but one that delivers superior electrical performance, greater design flexibility, and unparalleled long-term reliability—making it an indispensable technology for next-generation applications in 5G, automotive, and aerospace.

How Does the RO3035 Laminate's Thermal Stability Enhance PCB Reliability?

In high-frequency electronics, heat is an inevitable byproduct of operation. Components like power amplifiers (PAs) in cellular base stations or automotive radar modules generate significant heat. If the PCB substrate is not stable, this heat can cause catastrophic failures. The RO3035 laminate is engineered to prevent these failures through several key mechanisms:

1. Matched Coefficient of Thermal Expansion (CTE) Prevents Mechanical Failure

One of the most critical aspects of thermal stability is how much a material expands and contracts when heated or cooled.

The Problem: If the PCB laminate expands at a significantly different rate than the copper traces and plated through-holes, it creates immense stress. This can lead to cracked vias, broken circuit traces, and delamination (separation of the copper from the substrate). For a board with 21 vias and 63 pads, as in our standard offering, via integrity is paramount.

The RO3035 Solution: RO3035 has a low and well-controlled in-plane CTE:

• X & Y Axis: 17 ppm/°C
• Z Axis: 24 ppm/°C 

Crucially, the in-plane CTE (17 ppm/°C) is very close to that of copper (≈17 ppm/°C). This "CTE match" means the substrate and the copper circuits expand and contract in harmony during thermal cycles.

Reliability Enhancement: This drastically reduces mechanical stress on the plated through-holes and the copper-to-laminate bond. It prevents via barrel cracking and pad lifting, which are common failure points in less stable materials, ensuring the electrical connections remain intact over thousands of thermal cycles.

2. High Decomposition Temperature (Td > 500°C) Ensures Material Integrity

During assembly and operation, theRogersRO3035 PCB is subjected to high temperatures.

• The Problem: Standard FR-4 materials have a lower glass transition temperature (Tg) and can begin to decompose at soldering temperatures, leading to blistering, delamination, and a loss of mechanical strength.
• The RO3035 Solution: RO3035 is a ceramic-filled PTFE composite with an exceptionally high Decomposition Temperature (Td) exceeding 500°C. This is far beyond the peak temperatures encountered in typical lead-free soldering processes (which are around 240-260°C).
• Reliability Enhancement: The board remains mechanically and chemically stable during all assembly stages and throughout its operational life. This guarantees that the 0.37mm thin board will not warp, blister, or degrade when subjected to the heat of soldering components or from internal power dissipation, ensuring the physical integrity of the assembly.

3. Stable Dielectric Constant (Dk) Over Temperature Maintains Electrical Performance

For high-frequency circuits, electrical stability is just as important as mechanical stability.

• The Problem: In many materials, the Dielectric Constant (Dk) can shift significantly with temperature changes. For a circuit designed to operate at a specific frequency (e.g., 24 GHz for automotive radar or 28 GHz for 5G), a drifting Dk causes a shift in the impedance and the resonant frequency. This leads to signal distortion, loss of gain, and overall system performance degradation.
• The RO3035 Solution: Rogers 3035 offers a remarkably stable Dk of 3.50±0.05 across a wide temperature range. This is a core feature of its "thermal stability."
• Reliability Enhancement: Your circuit's performance remains predictable and consistent whether it's a cold start in winter or operating at peak load on a hot summer day. This is non-negotiable for applications like global positioning satellite antennas and cellular power amplifiers, where signal integrity is critical.

4. Low Dissipation Factor (Df) Minimizes Signal Loss and Heat Generation

The electrical properties of the laminate also contribute to thermal management.

• The Problem: At high frequencies, materials with a high loss tangent (Df) convert significant signal energy into heat. This self-heating effect can raise the board's local temperature, creating a feedback loop that further degrades performance and stresses components.
• The RO3035 Solution: With an ultra-low Dissipation Factor of 0.0015 at 10 GHz, RO3035 minimizes dielectric losses.
• Reliability Enhancement: Less signal energy is lost as heat. This results in a lower operating temperature for the PCB itself, which directly increases the mean time between failures (MTBF) for both the board and the surface-mounted components. This is a key benefit for power amplifiers, where efficiency and heat management are major design challenges.

Conclusion: A Synergistic Effect for Ultimate Reliability

The thermal stability of the RO3035 high frequency laminate is not a single property but a synergistic combination of its matched CTE, high Td, stable Dk, and low Df. For our RO3035 2-layer 10mil Immersion Gold PCB, this means:

• Mechanically Robust: It can withstand the rigors of assembly and harsh operating environments without suffering from cracked vias or delamination.
• Electrically Predictable: Its performance remains locked in, ensuring that your high-frequency design works as intended throughout its lifespan.
• Thermally Efficient: It runs cooler and manages heat more effectively, leading to a more reliable end-product.

This holistic thermal stability is precisely why this RO3035 10mil PCB is specified for the most demanding applications in the automotive, aerospace, and telecommunications industries, where failure is not an option. By choosing a PCB built onRO3035 substrate, you are not just buying a board; you are investing in long-term, predictable performance.

When Should You Specify a 2-Layer, 30mil TMM10i Board for Your Next Project?

In the complex world of PCB design, material and configuration selection is a critical decision that can make or break your project's performance, cost, and timeline. While a vast array of options exists, knowing the precise application for a specialized board like the 2-Layer, 30mil TMM10i PCB with Immersion Tin finish is key to leveraging its full potential.

This isn't a one-size-fits-all solution; it's a precision instrument. Specifying it at the right time ensures optimal performance, reliability, and cost-efficiency. You should seriously consider this specific PCB configuration in the following scenarios:

1. When Your Application Operates at High Frequencies (RF & Microwave)

This is the most compelling reason to choose this board. The Rogers TMM10i material is engineered specifically for high-frequency performance.

• Stable Dielectric Constant (Dk of 9.80±0.245): A high and stable Dk allows for the design of smaller wavelength circuits. This means you can create more compact filters, antennas, and couplers without sacrificing electrical performance. The low tolerance ensures your design behaves predictably in production, batch after batch.
• Low Dissipation Factor (0.0020 @ 10 GHz): At microwave frequencies, signal loss is a major concern. The low loss tangent of TMM10i ensures minimal signal attenuation, which is critical for maintaining efficiency in power amplifiers, signal integrity in transceivers, and sensitivity in receiving systems.
• Specify this board for: Power amplifiers, low-noise amplifiers (LNAs), filters, couplers, and oscillators operating in the GHz range.

2. When You Require Superior Thermal and Mechanical Stability

Environmental robustness is non-negotiable in many fields. The TMM10i substrate excels where temperature fluctuations and mechanical stress are a concern.

• CTE Matched to Copper: The Coefficient of Thermal Expansion (CTE) of TMM10i (19/19/20 ppm/°C) is closely matched to the copper foil (~17 ppm/°C). This is crucial for reliability. During thermal cycling (e.g., power on/off or environmental changes), the board and the copper traces expand and contract at nearly the same rate. This drastically reduces the risk of plated through-hole (PTH) barrel cracking, trace delamination, and long-term failure.
• High Decomposition Temperature (Td 425°C): This allows the board to withstand the high temperatures of lead-free solder assembly processes without degrading, ensuring manufacturing yield and long-term reliability.
• Resists Creep and Cold Flow: The thermoset composite structure maintains its dimensional stability under continuous mechanical stress, preventing deformation that could alter electrical characteristics.
• Specify this board for: Automotive radar, satellite communication systems, aerospace electronics, and any application destined for harsh environments.

3. When Your Design Relies on Reliable Plated Through-Holes (PTHs) and Vias

The product description explicitly mentions TMM10i is "designed for high plated thru-hole reliability." This is a foundational feature.

• Robust Via Construction: With a via plating thickness of 20µm and a material that bonds well with copper, the PTHs in this board are exceptionally robust. The 30mil (0.762mm) core thickness is manageable for a 2-layer board, ensuring a reliable plating process throughout the hole barrel.
• No Special Pre-Treatment Required: Unlike pure PTFE materials, TMM10i does not require a sodium napthanate treatment prior to electroless copper plating. This simplifies the fabrication process, reduces potential failure points, and improves overall PTH quality and consistency.
• Specify this board for: Dense interconnects, power grounds, and any design where the integrity of the connection between layers is paramount to the function and lifespan of the product.

4. When You Need a Planar Surface for Fine-Pitch Components or Wire Bonding

The Immersion Tin (ImSn) surface finish is a strategic choice for specific assembly needs.

• Flat, Planar Surface: Immersion tin provides a very flat surface, which is ideal for the fine-pitch components commonly found in RF circuits. It eliminates the "coplanarity" issues that can arise with HASL (Hot Air Solder Leveling) finishes.
• Excellent for Wire Bonding: The thermoset resin base of TMM10i provides a stable, non-porous surface that is highly reliable for both gold and aluminum wire bonding, a critical assembly process in many high-performance RF and microwave multi-chip modules.
• Specify this board for: Designs using fine-pitch BGA or QFN packages, modules requiring wire bonding, or any application where a perfectly flat soldering surface is critical.

5. When Your Circuit Complexity is Managed on Two Layers

A 2-layer design is often sufficient for many RF functional blocks like filters, amplifiers, or antenna feed networks. Using this TMM10i configuration in such cases is a model of cost-effective performance.

• Simplified Fabrication: A 2-layer board is less complex to manufacture than a multilayer one, leading to higher fabrication yields, shorter lead times, and lower costs.
• Optimized Stackup: The symmetric stackup (1oz Cu - 30mil TMM10i core - 1oz Cu) provides a consistent environment for controlled impedance lines on both layers, which is perfectly adequate for many microstrip and stripline-inspired designs.
• Ideal for Dedicated RF Modules: The provided PCB Statistics (e.g., 10 components, 15 vias, 2 nets) suggest this board is perfect for a specific, critical function within a larger system.
• Specify this board for: Individual RF sub-assemblies, patch antenna arrays, sensor modules, and other applications where the circuit complexity does not necessitate four or more layers.

When to Look for an Alternative

Conversely, you should consider a different PCB specification if your project has:

• High-Density Digital Logic: Requires 4 or more layers for power integrity and complex routing.
• Extreme Heat Dissipation Needs: While stable, TMM10i's thermal conductivity (0.76 W/m/K) may be lower than specialized metal-core or alumina substrates for high-power applications.
• A Need for On-Board Shielding: This requires dedicated ground planes or buried layers, which a 4+ layer board would provide.
• A Strict Budget for Consumer-Grade Electronics: TMM10i is a performance-grade material; for non-critical, low-frequency applications, standard FR-4 is far more economical.

Conclusion: Making the Strategic Choice

Specifying the 2-Layer, 30mil TMM10i high frequency PCB with Immersion Tin is a strategic decision for engineers and designers who need a reliable, high-performance substrate for demanding high-frequency and thermal applications. It is the ideal choice when your priorities are signal integrity at microwave frequencies, robust plated through-holes, exceptional thermal stability, and a reliable surface for assembly.

By understanding the unique synergy between the TMM10i material, the 30mil thickness, and the immersion tin finish, you can select this board for your next RF power amplifier, satellite communication module, or advanced radar system, ensuring it is built on a foundation of proven performance and reliability.

Why Choose a Silver/Gold Surface Finish for High-Frequency PCBs?

In the world of high-frequency and radio frequency (RF) PCB design, every decision impacts performance. From the laminate material to the trace geometry, engineers labor over details to minimize loss and preserve signal integrity. One of the most critical choices lies in the surface finish—the final coating applied to the exposed copper circuitry. While options like ENIG (Electroless Nickel Immersion Gold) and HASL (Hot Air Solder Leveling) are common, for demanding applications, the silver/gold plate (gold over silver) finish stands out as a superior solution.

Here’s a breakdown of why this specific finish is the go-to choice for high-performance PCBs, such as our TLY-3 2-layer 20mil board.

1. The Unmatched Electrical Performance of Silver

At high frequencies, especially into the millimeter-wave range (like 24 GHz, 77 GHz, and beyond), the "skin effect" becomes dominant. This phenomenon causes the electrical current to flow primarily on the outer surface of the conductor. Therefore, the properties of the surface finish itself directly influence the signal's insertion loss.

• High Conductivity: Pure silver is the most electrically conductive metal, even slightly better than copper. When used as a base plating layer, it creates an exceptionally low-loss path for RF signals. Compared to a standard ENIG finish, which uses a less-conductive nickel barrier layer, silver plating offers significantly lower signal loss at high frequencies.

• Smooth Surface Profile: The electroplating process for silver results in a very flat and uniform surface. This smoothness is crucial for consistent impedance control in delicate transmission lines like microstrips or coplanar waveguides, where surface roughness can increase loss and scatter signals.

2. The Protective and Reliable Role of Gold

While silver is an excellent conductor, it has a major Achilles' heel: it tarnishes and oxidizes easily when exposed to sulfur in the atmosphere. This oxidation layer is non-conductive and would severely degrade performance over time. This is where the thin layer of gold comes in.

• Inert Protection: Gold is a noble metal, meaning it does not oxidize or corrode in normal environments. The thin, immersion gold layer hermetically seals the underlying silver, protecting it from the elements and ensuring long-term shelf life and reliability. 
• Excellent Contact Properties: For PCBs designed to be plugged into a connector or make direct contact with a metal housing (e.g., in an antenna module), gold is ideal. It provides a stable, low-resistance contact interface that won't degrade through repeated mating cycles.

3. The Synergy of the Duo: Best of Both Worlds

The "gold over silver" finish is a classic case of a perfect partnership. Each metal plays a distinct role:

• Silver serves as the workhorse conductor, providing the ultimate electrical performance.
• Gold acts as the protective shield, guaranteeing long-term solderability, stable contact resistance, and reliability.
• This combination delivers a surface that is both electrically superior at high frequencies and robust enough for demanding automotive, aerospace, and telecommunications applications.

Comparison to Other Common Finishes

To fully appreciate the silver/gold finish, it helps to compare it to alternatives:

• vs. ENIG (Electroless Nickel Immersion Gold): ENIG is popular but problematic for very high frequencies. The nickel layer, while preventing copper diffusion, has poor conductivity and introduces magnetic losses, which are detrimental above a few GHz. Silver/gold avoids this lossy nickel layer entirely.
• vs. Immersion Silver: Immersion silver alone is a good option but is more susceptible to tarnishing and has a shorter shelf life than the gold-protected version.
• vs. OSP (Organic Solderability Preservative): OSP is a thin, organic layer that offers little to no protection for exposed contacts and can be unsuitable for certain assembly processes.

Conclusion: A Finish for Mission-Critical Applications

Choosing a silver/gold surface finish is not about luxury; it's a calculated engineering decision for applications where signal integrity and long-term reliability are non-negotiable. For our TLY-3 PCB  20mil Silver Gold board, this finish is the perfect complement to the high-frequency properties of the TLY-3 laminate. It ensures that the exceptional signal performance designed into the board is not compromised at the surface level, making it the ideal choice for:

• 77 GHz Automotive Radar Sensors
• Satellite Communication Phased Arrays
• Millimeter-Wave Antennas (Ka, E, W-Band)

When your design cannot afford unnecessary losses, the silver/gold finish PCB provides the electrical edge and enduring protection you need.

EE-Type Bobbin

1. Structural Features

The ferrite magnetic core of an EE-Type Bobbin is shaped like two symmetrical "E" letters combined, with the width of the central leg usually equal to that of the two side legs. This symmetrical structural design ensures a more uniform magnetic field distribution when winding the coil, which helps enhance the performance of the transformer. The pins of the EE-Type Bobbin are distributed on both sides of the bobbin, and their quantity and spacing vary according to different models and application requirements. Common sizes include EE5, EE8, EE13, EE19, etc. EE-Type Bobbins of different sizes are suitable for transformers of different power levels. For example, EE5 is used for low-power transformers and often applied in auxiliary power supplies for small electronic devices, while EE19 can be used in higher-power industrial power transformers.

2. Application Scenarios

EE-Type Bobbins are widely used in various types of transformers, including low-frequency transformers and high-frequency transformers. In the low-frequency field (e.g., power-frequency transformers), EE-Type Bobbins are often used in power transmission and distribution systems to convert high voltage into low voltage suitable for household and industrial use. In the high-frequency field (e.g., EE19 switching power supply transformers), EE-Type Bobbins can achieve efficient electrical energy conversion under high-frequency operating conditions, providing stable power for electronic devices. Additionally, EE-Type Bobbins are also applied in fields such as audio transformers and pulse transformers to meet the performance requirements of transformers in different applications.

3. Performance Advantages

The symmetrical structure of the EE-Type Bobbin results in uniform magnetic field distribution and low leakage inductance, which can improve the efficiency and power factor of the transformer. Therefore, it is also widely used in bobbins for EE05 LED driver transformer bobbin. Meanwhile, due to its simple structure, relatively mature manufacturing process, and low cost, it has high cost-effectiveness in the market. Besides, EE-Type Bobbins have high versatility—products with various sizes and pin configurations are easily available, which facilitates engineers' design and application work.

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Email: sales008@mycoiltech.com

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Name：Alex~Mycoiltech

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