In the electronics industry, printed circuit boards (PCBs), as the basic carrier of electronic components, play an indispensable role in various equipment and systems. Among them, medical PCBs have many differences from ordinary PCBs due to their special application environment and requirements.
This article will discuss in detail the differences between medical PCBs and ordinary PCBs in terms of design, materials, manufacturing processes, reliability and testing.
Medical PCBs need to be designed to meet the special needs of medical equipment, such as high precision, high stability, miniaturization, etc. Therefore, during the design process, medical PCBs pay more attention to considerations such as wiring accuracy, signal integrity, and electromagnetic compatibility (EMC).
In contrast, ordinary PCB boards may pay more attention to factors such as cost, production efficiency, and versatility in design.
✬ Wiring accuracy
Medical PCBs generally have higher wiring density, requiring smaller wire spacing to reduce signal interference and increase transmission speed. In addition, the wiring requirements for special signals such as differential signals and analog signals need to be considered.
✬ Signal integrity
Medical equipment has extremely high requirements for signal quality, and the design of medical PCBs must ensure that the signal is not distorted or attenuated during transmission. Therefore, factors such as transmission line effects, crosstalk, and reflection must be fully considered in the design, and corresponding measures must be taken for optimization.
✬ Electromagnetic compatibility
Medical equipment needs to operate stably in various complex electromagnetic environments, and medical PCB design must have good electromagnetic compatibility. This requires reasonable planning of the circuit board’s ground wires, power wires, and signal wires during the design stage to reduce electromagnetic interference (EMI) and electromagnetic radiation (EMR).
The material selection of medical PCBs is more stringent than that of ordinary PCBs, mainly in terms of substrate material, copper coating thickness, solder resist layer, etc.
✬ Substrate selection
Medical PCBs usually use high-performance, high-stability substrate materials, such as polyimide (PI), polytetrafluoroethylene (PTFE), etc. These materials have excellent high temperature resistance, chemical resistance, low dielectric constant and low loss, making them suitable for the demanding environment of medical equipment. Ordinary PCBs may use more common substrate materials such as FR-4.
✬ Copper thickness
Medical PCBs often require thicker copper layers to improve the circuit board’s electrical conductivity and current carrying capacity. At the same time, a thicker copper layer also helps improve the heat dissipation performance of the circuit board, ensuring that medical equipment can still work stably in high-temperature environments.
✬ Solder mask
The solder mask layer of medical PCBs needs to have good insulation properties and chemical corrosion resistance. Therefore, when it comes to the selection of solder mask ink, medical PCBs prefer to use high-performance, high-stability inks to ensure the long-term reliability of the circuit board.
The manufacturing process of medical PCBs is more complex and sophisticated than ordinary PCB boards. This is mainly reflected in the following aspects:
✬ Surface treatment
Medical PCBs usually require special surface treatment, such as gold plating, silver plating, etc., to improve the conductivity and oxidation resistance of the circuit board. These surface treatment measures also help improve the soldering performance and reliability of the circuit board.
✬ Fine processing
The size and shape of medical PCBs are often more complex and diverse, requiring fine cutting, drilling, milling and other processing techniques. These machining processes need to ensure high precision and stability to meet the precision requirements of medical equipment.
✬ Multilayer board production
Multilayer boards are commonly used in medical PCBs to achieve high-density wiring and complex circuit design. During the production process of multi-layer boards, parameters such as inter-layer alignment accuracy, lamination temperature and pressure must be strictly controlled to ensure the performance and reliability of the circuit board.
Medical PCBs have higher requirements than ordinary PCBs in terms of reliability. Medical equipment usually needs to maintain stable operation under long-term, high-load operating conditions, so medical PCBs need to have higher heat resistance, moisture resistance, shock resistance and aging resistance.
In order to improve the reliability of medical PCBs, a strict quality control system needs to be adopted during the manufacturing process to focus on monitoring key process links. At the same time, comprehensive functional and performance testing of finished circuit boards is also required to ensure that each circuit board can meet the high requirements of medical equipment.
Testing and Certification
Medical PCBs are more stringent in terms of testing and certification than ordinary PCBs. Since medical equipment is directly related to the life safety and health of patients, medical PCBs need to pass a series of rigorous tests and certifications to ensure their safety and effectiveness.
These tests and certifications include but are not limited to: electrical performance testing, environmental adaptability testing, biocompatibility testing, and compliance certification of medical device-related regulations and standards. Through these tests and certifications, it can be ensured that medical PCBs can work stably and reliably in various complex environments, providing a strong guarantee for the normal operation of medical equipment.
There are significant differences between medical PCBs and ordinary PCBs in terms of design, materials, manufacturing processes, reliability and testing. These differences enable medical PCBs to better meet the special needs of medical equipment and provide strong support for the development of the medical industry.
With the continuous advancement and innovation of medical technology, medical PCBs will continue to play an important role in promoting the development of medical equipment towards higher performance and higher reliability.