Ultrasound PCB: Key Design Considerations for Ensuring Patient Safety and Regulatory Compliance

technologyOctober 14, 2025 12 min read

Ultrasound PCBReal-Time Imaging PCBMobile Imaging PCBFluoroscopy PCBMedical Camera PCBMRI PCB

In the field of modern medical diagnostics, ultrasound imaging technology has become an indispensable tool due to its non-invasive, real-time, and high-resolution advantages. At the heart of this technology lies a precisely designed, reliable, and fully compliant Ultrasound PCB. It is not just an electronic substrate carrying complex signal processing algorithms but also a critical medical component directly tied to patient safety and diagnostic accuracy. As medical device regulatory experts, we must emphasize that designing an Ultrasound PCB is not merely an electronic engineering challenge—it is a systematic project involving electrical safety, risk management, quality systems, and global regulatory compliance.

This article will delve into the core principles and regulatory requirements that must be strictly adhered to during the design and manufacturing of Ultrasound PCBs, ensuring patient safety is prioritized from the very beginning.

The Regulatory Framework for Ultrasound PCBs: More Than Just Electronic Engineering

Any device used for medical diagnosis or treatment must have its core components developed under stringent regulatory frameworks. As a critical part of Class II medical devices (in most markets, such as the U.S. FDA and EU MDR), the design, manufacturing, and testing of Ultrasound PCBs must follow a comprehensive set of standards.

ISO 13485:2016: This is the gold standard for quality management systems (QMS) in the medical device industry. It requires that the entire process—from design inputs, design outputs, verification, and validation to production and post-market surveillance—be under controlled conditions. For PCB design, this means all design decisions, material selections, and changes must be documented and integrated into the risk management process.
IEC 60601 Series Standards: These are the general requirements for the safety and essential performance of medical electrical equipment. In particular, IEC 60601-1 defines fundamental principles for electrical, mechanical, and thermal safety. Additionally, IEC 60601-1-2 imposes strict requirements for electromagnetic compatibility (EMC).
ISO 14971:2019: The standard for medical device risk management. It requires manufacturers to systematically identify, assess, control, and monitor risks throughout the product lifecycle, ensuring the intended benefits outweigh the residual risks.

Together, these standards form a comprehensive compliance network, ensuring that the final ultrasound device—whether a large cart-based system or a portable Mobile Imaging PCB device—operates safely and effectively in clinical settings.

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IEC 60601-1 Core Requirements: Electrical Safety and Isolation Design

For Ultrasound PCBs and their connected probes that directly or indirectly contact patients, electrical safety is an absolute red line. IEC 60601-1 provides extremely detailed requirements, with the core focus on protecting patients and operators from electric shock hazards.

Means of Patient Protection (MOPP) and Means of Operator Protection (MOOP)

The standard categorizes protective measures into two levels:

Means of Operator Protection (MOOP): Designed to protect device operators such as doctors and nurses.
Means of Patient Protection (MOPP): Designed to protect patients, its requirements are far stricter than MOOP because patients may be physically weak or unconscious during diagnosis or treatment, rendering them unable to protect themselves.

The ultrasound probe and its interface circuit on the PCB belong to the "Applied Part," which comes into direct contact with the patient. Therefore, they must meet the highest isolation requirement of 2xMOPP. This means that during PCB layout, sufficient electrical clearance and creepage distance must be ensured between high-voltage circuits and patient-connected circuits.

IEC 60601-1 Electrical Safety Design Checklist

Isolation Level: Does the patient-applied part (e.g., probe interface) meet the 2xMOPP isolation requirement?
Creepage Distance/Electrical Clearance: Does the PCB layout meet the MOPP-required distances based on working voltage, pollution degree, and material group?
Leakage Current Test: Does the design ensure that patient leakage current, enclosure leakage current, and earth leakage current remain within standard limits under normal and single-fault conditions?
Dielectric Strength Test: Can critical isolation components on the PCB (e.g., isolation transformers, optocouplers) withstand the required test voltage (e.g., 4000VAC for 2xMOPP)?
Grounding and Protection: Is the protective grounding reliably connected? Is the impedance sufficiently low?
Component Selection: Do all safety-critical components (e.g., power supplies, fuses, connectors) have certifications compliant with IEC 60601-1?

To achieve these requirements, designs often employ Multilayer PCBs to create independent ground and power planes, effectively controlling current paths and electromagnetic interference.

ISO 14971 Risk Management: Mitigating Hazards from the Design Stage

Risk management is the cornerstone of medical device design. For Ultrasound PCBs, potential risks extend beyond electric shock and include misdiagnosis due to signal distortion, PCB overheating causing burns to patients or operators, and device malfunctions caused by software errors. ISO 14971 requires a closed-loop risk management process.

ISO 14971 Risk Management Process

Risk Analysis: Identify foreseeable hazards related to Ultrasound PCB. For example:
- Hazard: Power management chip failure on PCB causing overheating.
- Potential consequence: Excessive temperature in the probe handle, burning the operator or patient.
Risk Evaluation: Assess the probability and severity of each hazard to determine the risk level.
Risk Control: Implement measures to reduce unacceptable risks to acceptable levels. For example:
- Inherently safe design: Select components with higher temperature ratings.
- Protective measures: Add temperature sensors and over-temperature protection circuits on the PCB.
- Providing information: Clearly specify the operational temperature limits in the user manual.
Overall Residual Risk Evaluation: Assess whether the overall residual risk is acceptable after implementing all risk control measures.
Risk Management Report: Document the entire process to demonstrate product safety.
Production and Post-Production Information: Continuously monitor post-market product performance and feed new information back into the risk management process.

For a Real-Time Imaging PCB, signal accuracy is critical. Any interference may lead to misdiagnosis, which constitutes a high-severity risk. Therefore, during the risk analysis phase, the sources and impacts of electromagnetic interference (EMI) must be thoroughly considered.

High-Speed Signal Integrity and EMC Compliance

Ultrasound systems rely on high-speed data acquisition and processing from hundreds of piezoelectric crystal array elements, making the Ultrasound PCB a typical high-speed, high-density design. Ensuring signal integrity (SI) and power integrity (PI) is a prerequisite for achieving high-quality imaging, as well as the foundation for complying with the IEC 60601-1-2 Electromagnetic Compatibility (EMC) standard.

Signal Integrity (SI): The impedance of transmission lines must be strictly controlled in the design to minimize signal reflection, crosstalk, and timing jitter. This typically requires simulation and optimization using specialized High-Speed PCB design tools.
Power Integrity (PI): Providing stable and clean power to high-speed digital chips and sensitive analog front-end circuits is critical. Careful design of decoupling capacitor networks and power planes is necessary during PCB layout to suppress noise.
EMC Compliance: Medical devices must not interfere with other equipment in the environment (e.g., life support systems) and must also resist external electromagnetic disturbances (e.g., from mobile phones or surgical tools). This requires adequate shielding, filtering, and grounding at the PCB level. For Mobile Imaging PCBs, due to their variable operating environments, EMC design challenges are particularly pronounced. Similar design principles apply to other imaging equipment, such as Fluoroscopy PCBs and MRI PCBs, with the latter having even more stringent EMC requirements.

Design Control and Verification & Validation (V&V): The Cornerstone of ISO 13485

ISO 13485 requires the implementation of rigorous design control processes to ensure the final product meets user needs and regulatory requirements. This process is often referred to as the "design waterfall model," with clearly defined inputs, outputs, and review stages at each phase.

Design Control Gates

1. Design and Development Planning: Establish a project plan, clarifying resources, responsibilities, and objectives for each phase.
2. Design Input: Define product requirements, including functionality, performance, safety, regulatory standards (e.g., IEC 60601-1), and user needs. This serves as the foundation for all subsequent work.
3. Design Output: Translate design inputs into technical documentation, such as schematics, PCB layout files, bill of materials (BOM), manufacturing specifications, and test procedures. Design outputs must be verifiable.
4. Design Review: Conduct formal reviews of design outputs at critical milestones with cross-functional teams (including regulatory, quality, and engineering) to ensure alignment with design inputs.
5. Design Verification: Confirm that design outputs meet design inputs. For PCBs, this includes functional testing, signal integrity testing, safety compliance testing, and EMC testing. "Did we build the product right?"

6. Design Validation: Confirm that the final product meets the intended user needs and usage scenarios. Typically achieved through clinical evaluation or simulated use testing. "Did we build the right product?"

7. Design Transfer: Smoothly transition the validated design into production.

8. Design Change Control: Systematically evaluate, approve, implement, and document all design changes to prevent the introduction of new risks.

For Real-Time Imaging PCB, testing during the design verification phase is particularly critical. It must ensure that image quality and data processing speed meet the design input requirements under various simulated clinical conditions.

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Material Selection and Manufacturability: A Compliance Path from Prototype to Mass Production

The material selection and manufacturing process for medical-grade PCBs are also strictly regulated.

Material Selection: Stable-performance materials with strong traceability must be chosen. For example, the substrate's Tg value (glass transition temperature) needs to be sufficiently high to withstand multiple soldering processes and long-term thermal stress. For components like connectors that may come into contact with patients, materials must also consider biocompatibility (ISO 10993).
Design for Manufacturability (DFM): Production process limitations must be considered during the design phase to ensure the PCB can be stably and reliably mass-produced. This includes reasonable component layout, pad design, and test point planning.
Supply Chain Management: According to ISO 13485, key components and PCB manufacturers must undergo qualification audits and continuous evaluations. Choosing qualified suppliers that offer Turnkey Assembly services can effectively simplify supply chain management and ensure manufacturing compliance.

As ultrasound devices trend toward miniaturization and portability, such as handheld ultrasound, PCB requirements are becoming increasingly stringent. Designers may need to adopt HDI PCB (High-Density Interconnect) technology to achieve smaller sizes and higher integration or use Rigid-Flex PCB to accommodate complex device form factors. These advanced technologies are equally important when applied to other miniaturized medical devices like Medical Camera PCB.

Key Parameter Comparison for Medical PCBs

Parameter	Ultrasound PCB Requirements	General Consumer PCB Requirements	Compliance Importance
Traceability	Batch to individual component	Limited or no requirement	Extremely high (for recalls and root cause analysis)
Safety Standards	IEC 60601-1 (MOPP)	IEC 62368 / UL 60950	Mandatory (prerequisite for market access)
Change Control	Strict ECN/ECO process with risk assessment required	Flexible, primarily considers cost and performance	High (prevents introduction of unverified risks)
Service Life	Typically 7-10 years	Typically 2-5 years	High (related to device reliability and total cost of ownership)

Global Market Access: FDA, CE, NMPA Certification Pathways

Ultimately, all design and testing documentation will be compiled into a technical file to support product registration and approval in major global markets.

Guide to Major Market Certification Pathways

USA (FDA):
- Pathway: Typically 510(k) Premarket Notification.
- Core: Demonstrate that your device is "Substantially Equivalent" to a legally marketed predicate device.
- PCB-related documents: Schematics, layout, BOM, electrical safety and EMC test reports (IEC 60601-1 & 1-2), software validation documentation (if applicable).
EU (CE):
- Pathway: Compliance with Medical Device Regulation (MDR 2017/745).
- Core: Demonstrate product conformity with General Safety and Performance Requirements (GSPR) through conformity assessment procedures. Requires Notified Body review.
- PCB-related documents: As part of technical documentation, provide complete Design History File (DHF), risk management documents (ISO 14971), and clinical evaluation report.
China (NMPA):
- Pathway: Medical device registration.
- Core: Must complete type testing ("registration testing") at authorized testing centers within China.
- PCB-related documents: In addition to complete design materials, special attention should be paid to material biocompatibility reports and test reports compliant with Chinese national standards (GB 9706 series).

Whether it's **Fluoroscopy PCB** or **MRI PCB**, the compliance documentation of their core components is an indispensable part of the entire registration submission package.

Conclusion

Designing and manufacturing a compliant Ultrasound PCB is a complex and rigorous task that extends far beyond the scope of traditional electronic design. It requires the design team to maintain strong regulatory and safety awareness from the very beginning of the project, deeply integrating the ISO 13485 quality management system, ISO 14971 risk management principles, and IEC 60601 series of safety standards into every design decision. From component selection to PCB layout, from signal integrity to EMC protection, and finally to verification and validation, each step must prioritize patient safety as the ultimate goal. Only in this way can we ensure that the developed Ultrasound PCB drives safe, reliable, and effective medical devices, making a genuine contribution to global healthcare.