16MHz crystal oscillator is one of the most commonly used frequency control components in electronic circuits, providing accurate clock signals for microcontrollers, communication modules and embedded systems. As the core component of timing control, its stability directly affects the reliability of the entire system. ZHEJIANG A-CRYSTAL ELECTRONIC TECHNOLOGY CO.,LTD.  (A-Crystal) specializes in the production of various 16.000MHz Quartz Crystal Oscillator, products cover a variety of package sizes and temperature grades.

16MHz crystal oscillator package type  

The package size directly affects the crystal oscillator PCB layout, heat dissipation performance and mechanical stability. Mainstream packages include:

1. 3225 package (3.2mm×2.5mm) surface mount type  

-  Applicable scenarios  : Space-constrained design (IoT devices, wearable products)

-  characteristic  :

- Ultra-thin design (0.8mm height)

- Frequency stability ±10ppm~±30ppm

- Suitable for high density PCB layout

2. 5032 package (5.0mm×3.2mm) surface mount type  

-  Applicable scenarios  ：Industrial control, automotive electronics

-  characteristic  :

- Excellent temperature stability

- Wide operating temperature range (-40℃~+125℃)

- Higher power handling capability

3. 7050 package (7.0mm×5.0mm) surface mount type  

-  Applicable scenarios  : High reliability systems (5G equipment, medical electronics)

-  characteristic  :

- Excellent aging properties

- Low phase noise, suitable for RF applications

- Can be used for oven controlled crystal oscillator (OCXO) design

4. HC-49/S   PACKAGE

-  Applicable scenarios  ：Traditional equipment, test instruments

-  characteristic  :

- Easy to replace during the prototype development phase

- Large-volume purchasing has obvious cost advantages

5. Other packages:HC49U packages,HC-49SMD/SSMD packages etc 

16.000MHz crystal oscillator key parameters  

Parameters that need to be focused on when selecting:

Importance of Load Capacitance  

16MHz crystal oscillator needs  External matching capacitors (C1 & C2 ) are used to stabilize the oscillation. The actual load capacitance calculation formula is:

- If the specification requires CL=18pF, it is recommended to use  C1=C2=36pF  (Assuming stray capacitance 3pF)

- Wrong capacitance value will cause frequency deviation or failure to oscillate  

Typical Application of 16MHz Crystal Oscillator  

1. Microcontroller (MCU) and embedded systems  

- for  STM32, AVR, PIC, ESP series  Provides system clock

- Ensure the timing accuracy of communication interfaces such as UART, SPI, I2C, etc.

2. Wireless communication module  

- Reference clock source for RF modules such as Wi-Fi (ESP8266/ESP32), Bluetooth (nRF), Zigbee, etc.

- Low jitter crystal oscillators can significantly improve RF signal quality

 3. Industrial and automotive electronics  

- CAN bus, industrial Ethernet PHY, vehicle ECU and other key systems

- pass  AEC-Q200 qualified  Automotive grade crystal oscillator solutions

 4. Consumer Electronics  

• Real-time clock control for smart watches, drones, game controllers, etc.

Advantages of choosing A-Cryatal's 16MHz crystal oscillator  

-  High accuracy option (±10ppm available)  

-  Full range of packages (3225/5032/7050/HC-49)  

-  Industrial/automotive temperature range (-40°C~125°C)  

-  Low power consumption design (suitable for battery powered devices)  

16MHz crystal oscillator is the "heart" of modern electronic systems.  Package selection, load capacitance matching, and temperature characteristics directly affect system performance. Engineers must choose carefully when designing IoT, industrial control, or automotive electronics.

Zhejiang A-Crystal Company provides high reliability 16.000MHz crystal oscillators, which have been widely used in various industries. Welcome to request samples! If you need special frequency, higher precision and other customized requirements, please contact the technical team: market@acrystals.com or visit the official website: [www.acrystals.com](http://www.acrystals.com)

The 3225 crystal is a common quartz crystal resonator, which is widely used in electronic devices to provide a stable clock signal. Here is some basic information about the 3225 crystal:

1.Size

- The "3225" in the name of the 3225 crystal refers to its size of 3.2mm x 2.5mm. This miniaturized design makes it ideal for use in compact electronic devices.

2. **Frequency Range**

• The frequency range of 3225 crystal is usually between 12MHz and 54MHz, and the specific frequency depends on the application requirements.

Here are some common frequency of 3225 quartz crystal 

3. **Application**

- 3225 crystals are widely used in various electronic devices, including:

- Smartphones

- Tablets

- Wireless communication devices

- Internet of Things devices

- Consumer electronics

4. **Features**

- **High stability**: The 3225 crystal has high frequency stability and can maintain stable performance under different temperature and environmental conditions.

- **Low power consumption**: Suitable for low-power devices, helping to extend battery life.

- **Miniaturization**: The compact size makes it ideal for modern portable devices.

5. **Packaging**

- 3225 crystals are usually packaged using surface mount technology (SMT), which is convenient for automated production and high-density circuit board design.

6. **Operating temperature range**

- 3225 crystals usually have a wide operating temperature range, such as -40°C to +85°C, suitable for various environmental conditions.

7. **Load Capacitance**

- Common load capacitance values include 12pF, 18pF and 20pF, and the specific value depends on the circuit design requirements.

8. **Manufacturing process**

- The 3225 crystal uses a sophisticated quartz crystal processing process to ensure high accuracy and high reliability.

9. **Market**

- Due to its wide application and high performance, 3225 crystals occupy an important position in the global electronic component market.

10. **Selection considerations**

- When selecting a 3225 crystal, the following factors need to be considered:

- Frequency accuracy

- Load capacitance

- Operating temperature range

- Package type

- Supplier reliability and technical support

3225 crystal has become one of the indispensable components in modern electronic devices due to its miniaturization, high stability and wide range of applications.

In the early years, people relied on paper maps for self-driving trips. However, paper maps cannot be used to check routes while driving, and cannot quickly determine the current location. With the continuous development and progress of technology, navigation devices have quietly entered people's daily lives, bringing great convenience. Next, let's talk about the role of crystal oscillators in navigation devices.

First, the crystal oscillator provides an accurate time reference in the navigation device. By synchronizing with the external GPS satellite, the crystal oscillator can ensure that the time inside the navigation device is consistent with the global standard time. This is essential for the normal operation of the navigation device because it needs to accurately calculate information such as position, speed and direction.

Secondly, the crystal oscillator also provides a stable frequency signal. In radio navigation equipment, the crystal oscillator acts as an oscillator to generate a stable oscillation frequency. These frequency signals are used to modulate and demodulate wireless signals to achieve communication with navigation satellites or ground base stations. The stability and accuracy of the crystal oscillator are essential to ensure reliable communication between navigation equipment and the outside world.

In addition, crystal oscillators also play the role of frequency synthesis in radio navigation equipment. By combining multiple crystal oscillators together, higher frequency band signals can be generated to meet the needs of different navigation systems. This frequency synthesis technology enables radio navigation equipment to operate in a wide frequency range, improving the flexibility and adaptability of the navigation system.

Crystal oscillators play an important role in providing accurate time reference and stable frequency signals in radio navigation equipment. Its stability, accuracy and frequency synthesis capability are essential to ensure the normal operation of navigation equipment and reliable communication with the outside world. Therefore, crystal oscillators play an indispensable role in radio navigation equipment.

Simple Packaged Crystal Oscillators (SPXO)

SPXO is an oscillator for watches, which uses crystal resonance to create an electrical signal with a more precise frequency and are suitable for clock signal generators.

Voltage Controlled Crystal Oscillators (VCXO)

These crystal oscillators have a variable-capacitance diode inserted into a SPXO oscillation loop, and enables the oscillation frequency to change by varying the voltage of the external power supply. The temperature characteristic of these oscillation are equivalent to those of the SPXO loop and takes advantage of the good attributes of crystal resonators.

Temperature Compensated Crystal Oscillators(TCXO)

These high-precision crystal oscillators have a built-in circuit that corrects frequency variations resulting from temperature variations of the crystal resonator. It is optimal for applications where small frequency tolerance is required across a wide temperature.

Oven Controlled crystal Oscillator(OCXO)

OCXO is a super high-precision crystal oscillator with very small frequency variations by a built-in thermostatic bath, to maintain a constant temperature of the crystal resonator. Available to the frequency reference, such as instruments and infrastructure base stations.

Real Time Clock Module(RTC)

RTC is a high-precision crystal application product with built-in tuning-fork crystal oscillator,has an interrupt function and data provide function necessary for calendar clock function,such as year, month, day, hour, minute and second.

In electronic device design, the 32.768KHz crystal oscillator serves as the core component of Real Time Clocks (RTC), where stability andreliability are paramount. While EPSON's MC-306 series has long been a mainstream choice in the market, technological advancements and the need for supply chain diversification have made finding high quality alternatives a key concern for many engineers. The PMX206 series crystal oscillator from Zhejiang A Crystal Electronic Technology Co., Ltd. is specifically designed as a high performance alternative solution to meet this demand. 

Key Features of PMX206 Crystal (8038 SMD Tuning Fork Crystal PMX206, size 8.0*3.8*2.5 mm)

1. Excellent Frequency Stability  

Frequency range: 25.60KHz to 307.20KHz, covering a wide range of application needs  

Standard 32.768KHz frequency, fully compatible with MC-306  

Frequency tolerance: ±5ppm to ±100ppm (referenced at 25℃)  

Temperature coefficient:  0.034±0.006 ppm/℃², ensuring stable operation across various temperature environments  

2. Optimized Electrical Parameters  

High quality factor (Q): Typical value 75,000  

Series resistance (R1): 35KΩMin 50KΩMax  

Load capacitance (CL): Adjustable 6PF-30PF to accommodate different circuit designs  

Insulation resistance (IR): ≥500MΩ (DC100V±15V)  

Advantages of PMX206 Over MC-306  

1.   Wider Temperature Range  : PMX206 offers an operating range of  40℃ to +85℃, making it more suitable for extreme environments than the standard MC-306  

2.   Better Frequency Stability  : Excellent performance in temperature coefficient and aging rate ensures higher long term reliability  

3.   Flexible Load Capacitance Options  : Adjustable range of 6-30pF facilitates circuit design optimization  

4.   Supply Chain Advantages  : Zhejiang A Crystal, as a professional crystal oscillator manufacturer, provides stable supply assurance  

5.   Cost Effectiveness  : Competitive pricing while maintaining equal or better performance  

For engineers seeking alternatives to EPSON MC-306, the PMX206 offers excellent performance, reliable quality, and competitive pricing. Whether for new product designs or upgrades to existing products, PMX206 is a cost effective option worth considering. By choosing Zhejiang A Crystal, you not only get high quality crystal oscillator products but also professional technical support and supply chain security.  

Contact Us for Technical Support and Sample Requests  

Contact us today to learn how PMX206 can add value to your application!  

For more technical details about the PMX206 crystal or to request samples, please contact our sales team:  

Tel: 0086-576-89808609  

Email: market@acrystals.com  

Website: [www.acrystals.com](http://www.acrystals.com)  

32.768kHz crystal is a commonly used clock source, especially in electronic devices. This crystal is often used in real-time clock (RTC) and timing applications, such as watches, alarm clocks, thermometers, pedometers, etc.

Working principle:

32.768kHz crystal oscillator is an oscillator that generates a stable frequency through resonance phenomenon. It usually consists of a quartz crystal and related circuits.

1. Quartz crystal: Quartz crystal is a key component of the crystal oscillator. It is a material with a highly lattice structure and stable mechanical properties. The shape of the crystal can be cylindrical or flake with electrodes on both sides, flake is more common. The size of the quartz crystal determines the stability of the oscillation frequency.

2. Oscillation circuit: The oscillation circuit drives the quartz crystal to the resonance point and provides feedback to maintain the stability of the oscillation. The oscillation circuit usually consists of an amplifier, a feedback network and a compensation circuit.

- Amplifier: The amplifier is responsible for boosting the crystal oscillator's signal to offset the damping caused by the oscillation circuit and external load.

- Feedback network: The feedback network feeds a portion of the crystal oscillator's output signal back to the amplifier to maintain the stability of the oscillation. This feedback enhances at a specific frequency and attenuates at other frequencies, so that the oscillator only oscillates at the resonant frequency.

- Compensation circuit: The compensation circuit is used to compensate for the influence of temperature, power supply voltage and crystal aging on the oscillation frequency. It can be realized by combining a temperature sensor and a dedicated circuit.

Once the oscillator is working, the quartz crystal will generate a stable oscillation signal at a frequency of 32.768kHz through the oscillation circuit. This signal can be used to drive time-related electronic devices such as RTC after passing through the frequency divider.

It should be noted that the frequency of the 32.768kHz crystal oscillator was chosen because it is 2 to the 15th power and can be easily divided by multiples of 2 to produce a lower frequency clock signal.

A quartz crystal resonator is an electronic component that uses the piezoelectric effect of a quartz crystal to achieve frequency stabilization. The chemical composition of quartz is SiO2, which belongs to the hexagonal oxide mineral system, mainly including low-temperature quartz (α-quartz) and high-temperature quartz (β-quartz). This crystal produces a piezoelectric effect when subjected to pressure or heat, which is the fundamental physical property of its use as a resonant device.

In actual manufacturing, the basic structure of a quartz crystal resonator is: thin slices are cut from the quartz crystal at a specific azimuth angle (such as AT cut or BT cut), electrodes are made by silver plating on both sides, and the leads are welded and then packaged to form a complete device. The products are usually packaged in metal shells, but they can also be packaged in glass, ceramic or plastic. When an alternating voltage is applied to the electrodes, the chip will produce mechanical vibrations, and when the voltage frequency is consistent with the natural frequency of the chip, a significant piezoelectric resonance phenomenon will occur.

The piezoelectric effect of quartz crystal is characterized by bidirectional conversion: applying an electric field produces mechanical deformation (inverse piezoelectric effect), while applying mechanical pressure produces an electric field (postive piezoelectric effect). This characteristic makes its mechanical vibration equivalent to inductance L, which together with static capacitance C0 forms an LC resonant circuit. This structure enables the Q value of the quartz resonator to reach tens of thousands or even millions, which is far superior to ordinary LC oscillation circuits.

Quartz crystal resonators mainly operate in two modes: fundamental frequency and overtone. By optimizing the electrode design and the wafer cutting method, the performance of specific modes can be improved for different application scenarios. Due to their excellent frequency stability, these devices are widely used in communication equipment, computer systems, consumer electronics and other fields.

With the development of technology, modern quartz crystal resonators have been able to meet the diverse needs from ordinary consumer electronics to high-precision industrial equipment. Through special cutting methods and packaging processes, the temperature stability and reliability of the product can be further improved, allowing it to continue to play a key role in emerging fields such as 5G communications and the Internet of Things.

How to Choose Between RO4350B, PTFE, and Ceramic-Filled Substrates？

Introduction

High-frequency PCBs are critical in modern RF and microwave applications, including 5G communications, radar systems, and satellite technology. Selecting the right substrate material is essential to ensure signal integrity, thermal stability, and manufacturability. Three of the most commonly used high-frequency PCB materials are Rogers RO4350B, PTFE (Teflon), and ceramic-filled laminates.

In this guide, we’ll explore the properties, advantages, and trade-offs of each material and provide insights on how to choose the best option for your application. We’ll also showcase a real-world6-layer RF PCB example using RO4350B and RO4450F bondply to illustrate material selection in practice.

Key Considerations for High-Frequency PCB Materials

Before diving into material specifics, let’s outline the key factors that influence substrate selection:

• -Dielectric Constant (Dk)–Affects signal propagation speed and impedance control.
• -Dissipation Factor (Df)–Determines signal loss at high frequencies.
• -Thermal Conductivity–Important for heat dissipation in power applications.
• -Coefficient of Thermal Expansion (CTE)–Impacts reliability under thermal cycling.
• -Manufacturability–Some materials require specialized processing.
• -Cost- High-performance materials can be expensive.

Now, let’s compare the three leading high-frequency PCB materials.

1. RO4350B: The Cost-Effective High-Performance Option

Rogers 4350B is a woven glass-reinforced hydrocarbon/ceramic laminate that offers a balance between electrical performance and ease of fabrication.

Key Features of RO4350B

• -Dielectric Constant (Dk): 3.48±0.05 @ 10 GHz
• -Dissipation Factor (Df): 0.0037 @ 10 GHz (low loss)
• -Thermal Conductivity: 0.69 W/m/°K (better than FR4)
• -CTE: Low expansion (X/Y: 10-12 ppm/°C, Z: 32 ppm/°C)
• -Tg (Glass Transition Temp): >280°C (excellent thermal stability)
• -Moisture Absorption: 0.06% (minimal impact on performance)

Why Choose RO4350B?

✔Cost-Effective Alternative to PTFE–RO4350B performs close to PTFE but at a lower cost.

✔Compatible with Standard FR4 Processes–No special drilling or plating required.

✔Stable Dk Over Frequency & Temperature–Ideal for RF and microwave circuits.

Example: 6-Layer RF PCB Using RO4350B

Here’s a real-world PCB we manufactured using RO4350B cores and RO4450F bondply:

Layer Count: 6

Dimensions: 98.5 mm×68 mm (±0.15mm)

Min Trace/Space: 4/6 mils

Min Hole Size: 0.3mm

Blind Vias: L1-L2, L3-L6, L5-L6

Board Thickness: 1.8mm

Surface Finish: Immersion Gold

Solder Mask: Green (top & bottom)

Quality Standard: IPC-Class-2

Stackup Structure:

Top Layer (35µm Cu)

RO4350B Core (0.254mm)

Inner Layer (35µm Cu)

RO4450F Bondply (4mil, 2x)

RO4350B Core (0.762mm)

Bottom Layer (35µm Cu)

This design is optimized for RF applications with controlled impedance and low insertion loss.

2. PTFE (Teflon): The Ultra-Low Loss Solution

PTFE (Polytetrafluoroethylene) is the gold standard forultra-high-frequency PCBs due to its extremely low loss.

Key Features of PTFE

• Dk: 2.1–3.5 (varies with filler material)
• Df: As low as 0.0009 (best for mmWave applications)
• Thermal Stability: Excellent, but high CTE (~160 ppm/°C)
• Challenges: Requires specialized drilling/plating processes.

When to Use PTFE?

✔Millimeter-Wave (mmWave) Circuits (24GHz+, 5G, radar)

✔Extremely Low-Loss Applications (satellite comms, aerospace)

✖Not Ideal for Cost-Sensitive Projects (higher fabrication costs)

3. Ceramic-Filled Materials: High Thermal & Mechanical Stability

Ceramic-filled substrates (e.g.,Rogers RO3000 series) offer enhanced thermal conductivity and mechanical strength.

Key Features of Ceramic-Filled Laminates

• Dk: 3.0–10.2 (adjustable based on ceramic content)
• Df: 0.001–0.003 (low loss, but not as good as PTFE)
• Thermal Conductivity: Up to 4 W/m/°K (great for power amplifiers)
• CTE: Matches copper (~17 ppm/°C), reducing warping risks.

Best Applications for Ceramic-Filled PCBs

✔High-Power RF Devices (base stations, power amplifiers)

✔Applications Needing Heat Dissipation (automotive radar, LED PCBs)

Material Selection Guide: RO4350B vs. PTFE vs. Ceramic

Which One Should You Choose?

• For most RF applications (up to 20GHz), RO4350B Frequency PCB is the best balance of cost and performance.
• For mmWave (24GHz+), PTFE is ideal but expensive.
• For high-power/high-thermal applications, ceramic-filled laminates are superior.

Conclusion

Selecting the right high-frequency PCB material depends on your application’s frequency range, thermal requirements, and budget.

RO4350B PCB is the best all-around choice for most RF designs, offering low loss, stable Dk, and easy fabrication.

PTFE is unmatched for ultra-low-loss mmWave circuits but comes at a higher cost.

Ceramic-filled materials excel in high-power and high-thermal scenarios.

Our 6-layer RF PCB example demonstrates howRogers4350B and RO4450F bondply can be used effectively in real-world designs. If you need high-frequency PCBs with optimized material selection, we provide global manufacturing with IPC-Class-2 quality standards.

Need a custom RF PCB solution? Contact us today for expert guidance!

PTFE Materials Are Difficult to Process—How to Solve Lamination and Drilling Challenges?

Introduction

Polytetrafluoroethylene (PTFE), commonly known by the brand name Teflon (TFE), is a high-performance material widely used in printed circuit boards (PCBs) for high-frequency applications. Its low dielectric constant (Dk) and dissipation factor (Df) make it ideal for RF, microwave, and millimeter-wave circuits. However, TFE materials like Rogers RT/duroid 5880 present significant challenges in lamination and drilling due to their unique properties.

In this article, we’ll explore the key difficulties in TFE material PCB fabrication and provide practical solutions to overcome them. We’ll also highlight how our 3-layer rigid PCB with RTduroid 5880 and RO4450F bonding ply successfully addresses these challenges while maintaining high-frequency performance.

Why TFE Materials Are Difficult to Process

PTFE-based laminates like RT/duroid 5880 offer outstanding electrical properties, including:

• -Low dielectric constant (Dk = 2.2±0.02)
• -Ultra-low dissipation factor (Df = 0.0009 at 10 GHz)
• -Excellent thermal stability

However, these benefits come with manufacturing challenges:

1. Lamination Difficulties

• -Poor Adhesion: PTFE is inherently non-sticky, making it difficult to bond with copper layers.
• -Thermal Expansion Mismatch: PTFE has a higher coefficient of thermal expansion (CTE) than copper, leading to potential delamination.
• -Resin Flow Control: Excessive heat and pressure can cause resin squeeze-out, affecting dielectric thickness.

2. Drilling Challenges

• -Material Softness: PTFE is soft and prone to smearing during drilling, leading to poor via quality.
• -Thermal Sensitivity:Excessive heat from drilling can degrade PTFE’s electrical properties.
• -Hole Wall Roughness: Improper drilling can result in rough via walls, affecting signal integrity.

Solutions for Successful TFE PCB Fabrication

1. Optimizing Lamination for TFE Materials

a) Use Special Bonding Materials

To improve adhesion, we use RO4450F bonding ply—a thermoset material compatible withPTFE laminates. In our 3-layer PCB stackup, RO4450F ensures strong interlayer bonding while maintaining electrical performance.

Our PCB Stackup Example:

Layer 1: Copper (35μm)

Core: RT/duroid 5880 (1.575 mm)

Layer 2: Copper (35μm)

Bonding Ply: RO4450F (0.102 mm)

Core: RT/duroid 5880 (1.575 mm)

Layer 3: Copper (35μm)

b) Controlled Lamination Parameters

• Temperature & Pressure: Precise control prevents resin flow issues and maintains consistent dielectric thickness.
• Slow Ramp-Up Rates: Gradual heating minimizes thermal stress, reducing delamination risks.

2. Overcoming Drilling Challenges

a) Specialized Drill Bits & Parameters

• Carbide Drill Bits: Harder than standard drills, reducing PTFE smearing.
• Optimized RPM & Feed Rate: Prevents excessive heat buildup.

b) Laser Drilling for Micro-Vias

• For smaller holes (0.4mm in our PCB), laser drilling provides cleaner, more precise vias with minimal wall roughness.

c) Post-Drilling Treatments

• Plasma Etching: Removes PTFE residue from via walls.
• Via Plating (20μm in our PCB): Ensures reliable electrical connections.

Case Study: Our 3-Layer RT/duroid 5880 PCB

To demonstrate successful TFE material processing, here’s a breakdown of our high-frequency PCB solution:

Key Specifications:

Material: RT/duroid 5880 (core) + RO4450F (bonding ply)

Layers: 3

Board Thickness: 3.3 mm

Min Trace/Space: 5/7 mils

Min Hole Size: 0.4 mm

Via Plating Thickness: 20μm

Surface Finish: Immersion Gold (enhances signal integrity)

Why This Design Works for High-Frequency Applications?

✔Low Signal Loss: RT/duroid 5880’s ultra-low Df ensures minimal RF attenuation.

✔Stable Dk: Uniform dielectric constant across frequencies.

✔Robust Construction: RO4450F bonding ply prevents delamination.

✔Precision Drilling: 0.4mm vias with 20μm plating ensure reliable interconnects.

Conclusion: Partner with a PCB Supplier Experienced in TFE Materials

Fabricating High Frequency PTFE PCB with RT/duroid 5880 and other PTFE-based materials requires specialized expertise in lamination, drilling, and thermal management. By optimizing bonding materials, drilling techniques, and lamination processes, we deliver high-performance PCBs for RF, aerospace, and millimeter-wave applications.

Looking for a reliable TFE PCB supplier? Our 3 Layer High Frequency PCB RT/duroid 5880 is IPC-Class-2 compliant, electrically tested, and available worldwide. Contact us today for high-frequency PCB solutions tailored to your needs!

What Are the Design Considerations for Hybrid High-Frequency PCBs?

Introduction

Hybrid (mixed dielectric) high-frequency PCBs combine different materials to optimize electrical performance, thermal stability, and manufacturability. These mixed dielectric hybrid boards are widely used in RF/microwave applications, aerospace, radar systems, and telecommunications, where signal integrity and thermal management are critical.

Designing hybrid PCB requires careful consideration of material properties, layer stackup, signal integrity, and manufacturing constraints. In this article, we explore key design considerations and provide practical insights, using a 4-layer hybrid PCB (RO4350B + High-Tg FR-4 S1000-2M) as an example.

1. Material Selection and Compatibility

Key Factors in Material Selection

Dielectric Constant (Dk) & Loss Tangent (Df):

• -High-frequency signals require stable Dk and low-loss materials (e.g., Rogers RO4350B with Dk=3.48, Df=0.0037).
• -FR-4 (S1000-2M) provides mechanical support but has higher loss, so it’s best used in non-critical layers.

Thermal Expansion (CTE) Mismatch:

• -RO4350B has a CTE close to copper (X/Y: 10-12 ppm/°C), reducing warpage and via reliability issues.
• -S1000-2M offers excellent Z-axis CTE for plated through-hole (PTH) reliability.

Thermal Conductivity & Tg:

• -RO4350B has a high Tg (>280°C) and thermal conductivity (0.69 W/m/°K), making it suitable for high-power RF designs.
• -S1000-2M (Tg 180°C) provides mechanical stability and lead-free compatibility.

Example PCB Construction

Our 4-layer hybrid circuit board combines:

Signal Layers (RO4350B): Optimized for RF performance.

Core/Prepreg (FR-4 S1000-2M): Provides structural integrity.

Stackup:

Layer 1 (RF Signal): 35μm Cu + RO4350B (0.254mm)

Layer 2 (Ground/Power): 35μm Cu + Prepreg (0.254mm)

Layer 3 (Inner Signal): 35μm Cu + S1000-2M (0.8mm)

Layer 4 (Bottom Layer): 35μm Cu

2. Signal Integrity and Impedance Control

Critical Design Rules

Controlled Impedance Routing:

• RO4350B’s stable Dk allows precise impedance matching (e.g., 50Ωmicrostrip lines).
• Use field solvers to calculate trace width/spacing (e.g., 4/6 mil traces in our example).

Minimizing Crosstalk & Loss:

• Keep high-speed traces short and avoid sharp bends.
• Use ground planes (Layer 2 in our stackup) to reduce interference.

Via Optimization:

• Our example Hybrid PCB Board PCB uses 0.20mm minimum hole size with 20μm plating thickness for reliability.
• Avoid blind vias to simplify manufacturing (as seen in our design).

3.Thermal Management Considerations

Preventing Delamination & Warpage

• CTE Matching: RO4350B’s low CTE reduces stress between layers.
• Thermal Relief in Pads: Prevents excessive heat during soldering.

Heat Dissipation Strategies

• Copper Weight: Our PCB uses 1oz (35μm) copper for balanced current handling and heat spreading.
• Surface Finish: ENIG (Electroless Nickel Immersion Gold) ensures reliable solderability and corrosion resistance.

4. Manufacturing and Reliability

Fabrication Tolerances

• Board Dimensions: 173mm x 85.3mm (±0.15mm tolerance).
• Solder Mask & Silkscreen: Green solder mask (top/bottom) with white/green silkscreen for component marking.

Quality Assurance

• 100% Electrical Testing: Ensures no short/open circuits before shipment.
• IPC-Class-2 Compliance: Guarantees reliability for commercial applications.

5. Applications of Hybrid High-Frequency PCBs

Our example PCB (RO4350B + S1000-2M) is ideal for:

✅Radar & Guidance Systems (stable Dk, low loss)

✅5G & Millimeter-Wave Antennas (precise impedance control)

✅Aerospace & Defense Electronics (high thermal reliability)

Conclusion

Designing hybrid high-frequency PCBs requires a balance between material properties, signal integrity, and manufacturability. By selecting compatible materials (like RO4350B FR-4 hybrid PCB), optimizing stackup, and following best practices in impedance control and thermal management, engineers can achieve high-performance RF/microwave designs.

Looking for a reliable hybrid PCB supplier? Our 4-layer mixed-dielectric PCB (RO4350B + S1000-2M) meets stringent RF and thermal requirements while ensuring cost-effective production. Contact us today for your high-frequency PCB needs!