FAQs
Basics of Crystal Devices and How to Choose the Right One
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What role do crystal devices play in electronic equipment?
Crystal devices act like the “conductor of an orchestra” or the “heartbeat” of electronic systems.
They generate the precise reference signal (clock) that allows digital systems to process data and communicate at the correct timing. Without this timing signal, modern electronics cannot operate reliably.
Crystal devices are essential components used in a wide range of electronic products, including smartphones, PCs, automotive electronics, and wireless communication devices.
・Smartphones
・Personal computers
・Automotive electronics
・Wireless communication devices
・Industrial and IoT equipment
By providing an accurate and stable clock signal, crystal devices ensure that processors, communication modules, and sensors operate in perfect synchronization. -
Should I choose a crystal unit or a crystal oscillator?
The best choice depends on your development resources and cost requirements.
【Crystal Unit (Resonator)】
A crystal unit requires the customer to design an external oscillation circuit using an IC. While circuit matching and tuning are required, this approach enables lower cost and greater design flexibility.
【Crystal Oscillator】
A crystal oscillator integrates the optimal oscillation circuit and crystal inside the package. Once power is supplied, it immediately outputs a stable clock signal.
This option is ideal when you want to:
・Reduce circuit design complexity
・Improve noise immunity
・Shorten development time
・Ensure stable timing performance
View Product Lineup -
How should I choose between kHz crystals (tuning fork type) and MHz crystals (AT-cut, etc.)?
The selection mainly depends on the application purpose and power consumption requirements.
【kHz crystals (32.768 kHz tuning-fork type)】
These are typically used for:
・Timekeeping functions
・Sleep-mode timing
・Low-power standby operation
They operate with extremely low power consumption, making them ideal for battery-powered devices.
【MHz crystals (AT-cut, etc.)】
These are used as the main system clock for:
・High-speed digital processing
・Wireless communication (Wi-Fi, Bluetooth, etc.)
・Microcontrollers and processors
River Eletec provides industry-leading ultra-miniature crystal devices in both the kHz and MHz frequency ranges. -
What is the difference between AT-cut and GT-cut crystals?
The difference lies in the cutting angle used when slicing the quartz crystal.
【AT-cut crystals】
・Suitable for frequencies from several MHz to hundreds of MHz
・Excellent temperature stability
・Widely used in communication equipment and digital electronics
・The most common crystal cut type
【GT-cut crystals】
・Used in the kHz to several MHz frequency range
・Offers extremely high frequency stability over a wide temperature range
・More difficult to manufacture due to the precise cutting angle required
Because of their superior temperature characteristics, GT-cut crystals are suitable for high-reliability and precision timing applications.
River Eletec GT-cut product: GTXO-04
River Eletec’s Proprietary Technologies
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What is the greatest advantage of photolithography technology?
The greatest advantage of photolithography technology is its ability to achieve ultra-fine precision beyond the limits of conventional mechanical processing such as polishing or stamping.
By applying semiconductor manufacturing techniques—specifically photolithography used in semiconductor fabrication—to the three-dimensional processing of quartz, extremely small crystal devices can be manufactured with minimal dimensional variation and highly precise electrode patterns.
This enables the formation of ideal crystal shapes and electrode structures even at microscopic scales, which is a key factor behind River Eletec’s ability to produce some of the world’s smallest crystal resonators. -
Does miniaturizing the crystal device affect performance such as ESR?
In general, when the crystal element becomes smaller, ESR (Equivalent Series Resistance) tends to increase, which can make oscillation more difficult.
However, River Eletec overcomes this challenge through its proprietary Electron Beam Sealing (EBS) and Metal Diffusion Sealing (MDS) technologies. These technologies maintain an extremely high vacuum level inside the package, minimizing energy loss during vibration.
As a result, even in ultra-miniature crystal devices, River Eletec can maintain high Q values and low ESR, enabling miniaturization without compromising performance. -
How is the proprietary “KoT cut OPAW technology” different from conventional AT-cut crystals?
The biggest difference is that KoT cut OPAW technology overcomes the conventional barrier to ultra-high-frequency operation.
With traditional AT-cut crystals, achieving higher frequencies requires the crystal element to become extremely thin. This creates manufacturing limitations and can negatively affect mechanical stability.
In contrast, KoT cut technology enables high-frequency oscillation in the fundamental mode while maintaining sufficient crystal thickness. This allows stable operation together with excellent temperature characteristics.
In addition, OPAW (Orthogonal Plate Acoustic Waves) vibration technology suppresses unwanted vibration modes and noise, enabling extremely clean timing signals.
By combining these technologies, River Eletec achieves ultra-low jitter performance, which is essential for next-generation applications such as optical transceivers, high-speed networking equipment, and AI data center infrastructure. -
In which countries are the patents for KoT cut technology registered?
The KoT cut OPAW technology is protected by patents not only in Japan but also in several major global markets, including the United States, the United Kingdom, China, and Taiwan.
This international patent portfolio reflects River Eletec’s innovative approach to crystal device technology and provides a strong intellectual property foundation. As a result, customers can leverage this unique technology to gain technical advantages in next-generation module development on a global scale.
Circuit Design, PCB Mounting, and Handling
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Can I request a circuit matching evaluation when implementing a crystal unit?
Yes, we provide circuit matching evaluation services.
The oscillation margin and frequency accuracy of a crystal unit can vary depending on the compatibility between the crystal device and the customer’s PCB design. Proper matching of circuit constants is therefore important to ensure stable oscillation performance.
If you send us your evaluation board or PCB, our experienced engineers will analyze the oscillation circuit and determine the optimal circuit parameters for matching. We will then provide our recommendations together with a detailed technical report.
Please feel free to contact us via the Contact Form for further consultation. -
Can I request production with a specific (custom) frequency?
Yes, custom frequency specifications may be available depending on the product and application requirements.
If you need a special frequency, tighter frequency tolerance, or other customized specifications, please contact us with your requirements through the [Contact Form]. Our engineering team will review your application and propose the most suitable solution.
Leveraging River Eletec’s flexible design and manufacturing capabilities, we strive to provide crystal devices optimized for your specific system requirements. -
What is the recommended reflow (soldering) temperature profile?
Recommended reflow temperature profiles are available for each product family.
River Eletec’s surface-mount crystal devices are generally designed to comply with lead-free soldering processes, typically based on a reflow profile with a peak temperature of up to 260°C.
For detailed temperature conditions and recommended reflow profiles, please refer to the datasheet for each product or contact us through the Contact Form for further assistance. -
Are there any precautions when mounting ultra-miniature packages on a PCB?
Yes. When mounting ultra-miniature packages such as 1.2 × 1.0 mm devices, special care is required because of their extremely small footprint.
We recommend designing the PCB according to the land pattern (pad design) specified by River Eletec. Proper land dimensions and solder pad layout are essential to ensure reliable solder joints and stable mounting.
In addition, the following factors are important for preventing mounting defects:
・Optimizing the pickup nozzle size of the placement machine
・Proper control of solder paste volume
・Maintaining accurate component placement during automated assembly
River Eletec provides detailed mounting and PCB design guidelines to support reliable implementation. Please feel free to request these documents through the Contact Form. -
Are crystal devices vulnerable to shock? Are there precautions for handling or dropping them?
River Eletec’s crystal devices offer excellent shock resistance thanks to proprietary technologies such as Metal Diffusion Sealing (MDS) and Electron Beam Sealing (EBS), which provide a highly robust package structure.
However, crystal devices are precision components that contain thin quartz elements inside the package. Excessive mechanical stress applied to the PCB, or dropping the device onto a hard surface, may cause performance degradation.
To maintain optimal performance and reliability, careful handling during storage, assembly, and transportation is recommended. -
Can ultrasonic cleaning be performed after mounting the crystal device on a PCB?
As a general rule, ultrasonic cleaning is not recommended for crystal devices.
If the ultrasonic frequency used in the cleaning equipment is close to the resonant frequency of the internal quartz element, resonance may occur. This can potentially damage the crystal element inside the package.
Depending on the product type and cleaning conditions, ultrasonic cleaning may be possible in some cases. However, we strongly recommend conducting preliminary verification tests under the customer’s actual process conditions before applying ultrasonic cleaning in production.
Quality, Environmental Compliance, and Standards
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How do you ensure long-term reliability and quality assurance?
River Eletec maintains a rigorous quality management system throughout the entire process—from development to mass production—based on ISO 9001 certification.
One of the most critical factors affecting product lifetime is hermetic sealing. River Eletec’s proprietary Metal Diffusion Sealing (MDS) technology bonds metals at the molecular level without using adhesives or glass frit.
This advanced sealing method maintains an extremely high vacuum inside the package, even under severe temperature changes and long-term operating conditions. As a result, River Eletec crystal devices achieve exceptional long-term reliability with minimal performance degradation over time. -
Are your products compliant with RoHS and REACH regulations (lead-free compliant)?
Yes. River Eletec’s main products comply with major environmental regulations, including the RoHS Directive and the REACH Regulation, and are designed to support lead-free requirements.
By complying with these regulations, River Eletec contributes to reducing hazardous substances in electronic components and supports environmentally responsible manufacturing.
River Eletec is committed to providing crystal devices that meet both high performance requirements and sustainable environmental standards. -
Are your products compliant with automotive standards such as IATF 16949 and AEC-Q200?
Yes. River Eletec supports automotive industry requirements with both certified manufacturing systems and automotive-grade products.
Our major production facilities have obtained certification for IATF 16949, the globally recognized quality management system standard for the automotive industry. This certification ensures a highly rigorous quality control framework suitable for automotive applications.
In addition, River Eletec offers a wide range of crystal devices that comply with AEC-Q200, the reliability testing standard for passive electronic components used in automotive electronics.
Through strict system management and robust product design, River Eletec supports the development of next-generation mobility systems where high reliability and safety are essential, particularly as vehicle electrification continues to advance.
View Automotive Applications
Purchasing, Samples, and Lead Times (for Procurement & Purchases)
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Can I request free samples for evaluation and prototyping?
Yes, we offer free samples for design verification and evaluation.
Please provide details such as the desired product series, frequency, and application, and we will promptly arrange the most suitable samples for you and your team.
You can request samples via Request a Free Sample. -
What are your minimum order quantity (MOQ) and packaging specifications?
Our surface-mount crystal devices are typically supplied in tape-and-reel (embossed tape) packaging, compatible with automated assembly equipment.
The minimum order quantity (MOQ) varies depending on the product size, but typically ranges from 3,000 to 5,000 units per reel.
We also support small-quantity orders for prototyping and evaluation. Please feel free to contact us with your requirements. -
What is the typical lead time for mass production requests?
Lead times vary depending on product specifications and factory capacity.
For standard crystal devices, typical lead times range from several weeks up to approximately six weeks.
We prioritize a stable supply in line with our customers’ production plans. For detailed lead time information and forecast discussions, please contact our sales representative. -
Where are your products manufactured?
Our products are primarily manufactured in Japan at Aomori River Techno Corporation (Aomori and Hiraga plants). Production is also carried out at our overseas manufacturing subsidiary in Xi’an, China.
By establishing a robust global production network, we ensure stable supply and operational resilience against risks such as natural disasters and geopolitical uncertainties, delivering reliable products to customers worldwide.