What is the difference between a crimped, soldered, and compression connector termination?
Connector Termination Methods
The method used to attach a connector to a cable determines the quality of the electrical transition from the cable to the connector, affecting insertion loss, return loss, power handling, and long-term reliability. Each method has distinct advantages for specific applications.
| Parameter | Semi-Rigid | Conformable | Flexible |
|---|---|---|---|
| Loss (dB/m at 10 GHz) | 0.8-2.5 | 1.0-3.0 | 1.5-5.0 |
| Phase Stability | Excellent | Good | Fair |
| Bend Radius | Fixed after forming | Hand-formable | Continuous flex OK |
| Shielding (dB) | >120 | >90 | >60-90 |
| Cost (relative) | 2-5x | 1.5-3x | 1x |
Cable Selection Criteria
Soldered connections create a metallurgical bond between the connector and cable conductors, providing the lowest resistance and most intimate contact. The center conductor is soldered to the connector pin, and the outer conductor (shield) is soldered to the connector body. When properly executed, soldered connections provide insertion loss indistinguishable from the cable itself. The disadvantages are the skill required, the heat applied to the cable (which can damage PTFE dielectric), and the time per assembly.
- Performance verification: confirm specifications against the application requirements before finalizing the design
- Environmental factors: temperature range, humidity, and vibration affect long-term reliability and parameter drift
- Cost vs. performance: evaluate whether the application demands premium components or standard commercial grades
- Interface compatibility: verify impedance, connector type, and mechanical form factor match the system architecture
Loss and Phase Stability
Crimp connections use mechanical deformation (crimping) to compress the connector sleeve around the cable, creating a gas-tight metal-to-metal contact. Modern crimp tools produce highly consistent connections because the crimp dimensions are controlled by the die geometry. Crimp connections avoid heat damage, are faster than soldering (30 seconds vs 5 minutes per connector), and are preferred for production cable assemblies.
Frequently Asked Questions
Which is best for high-frequency performance?
Soldered, because the impedance transition can be precisely controlled. At frequencies above 18 GHz, the crimp sleeve geometry creates a measurable impedance discontinuity. Precision RF cables for VNA use are almost always soldered.
Can I crimp precision connectors?
Most precision-grade (3.5mm, 2.92mm, 2.4mm) connectors are solder-attach only because the crimp geometry would introduce unacceptable impedance discontinuities at their operating frequencies. SMA and N-type connectors are available in both crimp and solder versions.
What about push-on connectors?
Push-on connectors (QMA, SMPM, SMP) eliminate the threaded coupling mechanism for fast connections. They are used in high-density applications (phased arrays, satellite equipment) where hundreds of connections must be made quickly. RF performance is moderate (typically specified to 18-40 GHz depending on type).