Crystal resonators are vital components in frequency control and timing applications, ranging from consumer electronics like smartphones and laptops to industrial equipment and military applications. The method used to seal these resonators can significantly impact their performance and reliability. Two common sealing techniques are cold weld sealing and resistance weld sealing. In this short blog post, we’ll compare the differences between these two methods and explain their advantages and disadvantages.
Cold Weld Sealed Crystal Resonators
Cold weld sealing is a manufacturing process that involves creating a hermetic seal without the application of heat. This technique is often used for crystal resonators due to its ability to maintain the integrity of sensitive frequency control and timing devices. Here are some key points to consider:
- Hermetic Seal
Cold weld sealing offers an excellent hermetic seal, preventing the entry of moisture, gases, and contaminants. This seal ensures the crystal resonator’s long-term stability and reliability. - Low Thermal Stress
Since no heat is applied during the sealing process, cold weld sealing minimizes thermal stress on the crystal and other components. This is crucial for maintaining the resonator’s frequency accuracy and stability. - Clean and Residue-Free
Cold weld sealing leaves no residue or flux behind, contributing to a cleaner and more reliable end product.
Resistance Weld Sealed Crystal Resonators
Resistance weld sealing is another common method used to hermetically seal crystal resonators. Unlike cold welding, resistance welding applies heat to create the seal. Here are some key considerations for resistance weld sealed crystal resonators:
- Speed of Production
Resistance welding is a faster process compared to cold welding, making it a preferred choice for high-volume production environments. - Suitable for Larger Components
Resistance welding can handle larger and more complex components, which may be advantageous in certain applications. - Potential for Thermal Stress
The application of heat in resistance welding can introduce some thermal stress to the crystal and surrounding materials. This may affect the resonator’s performance, especially in high-precision applications. - Potential for Contamination
The resistance welding process requires that the two metals to be joined must be melted and this can result in outgassing and splatter which can result in some level of contaminants being trapped inside the sealed enclosure. This can result in increased crystal aging rates and degraded phase noise.
Selecting the Right Sealing Method
The choice between cold weld sealing and resistance weld sealing depends on various factors, including the specific application, production volume, and performance requirements. Here are some guidelines to consider:
- Cold Weld Sealing
Opt for cold weld sealing when precision, long-term stability, and minimal thermal stress are critical. This method is ideal for applications where the resonator operates in extreme conditions or needs to maintain precise frequency accuracy. - Resistance Weld Sealing
Choose resistance weld sealing when production speed and cost efficiency are a priority, and when the resonator’s size and complexity necessitate this sealing method.
Conclusion
Crystal resonators play a crucial role in frequency control and timing devices, and selecting the right sealing method is essential to ensure their performance and reliability. Cold weld sealing and resistance weld sealing offer distinct advantages and disadvantages, and the choice between the two should be based on the specific requirements of your application. Whether it’s the precision of cold weld sealing or the efficiency of resistance weld sealing, understanding the differences between these techniques can help you make an informed decision and ensure the success of your frequency control and timing device.
Authored by:
Luke Mueller, Managing Director
William Walsh, Marketing & Communications Manager