Materials Selection for Medical-Grade Ultrasound PCBs

Ultrasound imaging systems demand high-precision, high-frequency signal transmission, reliability, and biocompatibility. At the heart of these systems lies the PCB, and selecting the right materials is critical to ensure safety, accuracy, and long-term performance in medical applications.

Why Material Selection Matters in Medical Ultrasound PCBs?

In medical-grade applications, especially diagnostic imaging, PCBs must:

• Support high-frequency signal transmission (typically 20–100 MHz)
• Ensure thermal stability and low signal loss
• Be compatible with biocompatible or non-toxic materials
• Maintain dimensional stability during sterilization
• Offer high reliability in compact medical devices

Commonly Used Materials for Medical Ultrasound PCBs

1. High-Frequency Laminates

• Materials: Rogers RO4350B, Taconic RF-35
• Features: Low dielectric loss (Df), stable dielectric constant (Dk)
• Application: Signal layer in transducer driver boards

2. FR-4 with Enhanced Tg

• Materials: FR-4 Tg170+, S1000-2M
• Features: Good thermal performance, cost-effective
• Application: Power modules, control boards

3. Polyimide for Flex Circuits

• Features: High flexibility, excellent heat resistance
• Application: Probe interconnects, wearable ultrasound devices

4. Ceramic Substrates

• Materials: Al₂O₃ (alumina), AlN (aluminum nitride)
• Features: Exceptional thermal conductivity, used for miniaturized high-power designs
• Application: High-end diagnostic ultrasound front-ends

Key Design Considerations

• Dielectric Constant Control: Essential for maintaining signal speed and impedance matching
• Loss Tangent (Df): Lower Df ensures better signal clarity and lower distortion
• Moisture Absorption: Materials with low moisture absorption resist degradation during sterilization
• RoHS & Biocompatibility Compliance: Must meet medical regulations such as RoHS, REACH, and FDA-related standards

Choosing the right PCB materials for medical-grade ultrasound devices is more than an engineering decision—it’s a matter of patient safety and clinical precision. Partnering with an experienced PCB manufacturer familiar with medical standards ensures your product meets both regulatory and performance requirements.