Technical measures to improve the reliability of PCB equipment

Technical measures to improve the reliability of PCB equipment: scheme selection, circuit design, circuit board design, structural design, component selection, manufacturing process and other aspects. The specific measures are as follows:

(1) Simplify scheme design.

When designing the scheme, under the premise of ensuring that the equipment meets the technical and performance indicators, the design should be simplified as much as possible, and the circuit and structural design should be simplified to make each component the simplest design. The modular design method popular in the world today is an effective measure to improve the reliability of equipment. The function of the block is relatively simple, and the system is composed of modules, which can reduce the complexity of the design and standardize the design. A large number of facts at home and abroad have proved this point. Product design should adopt a modular design method.

(2) Use modules and standard components.

Modules and standard components are products that have been proven to be highly reliable after a large number of tests and extensive use. Therefore, they can fully eliminate the defects and hidden dangers of the equipment, and also bring convenience to replacement and repair after problems occur. The use of modules and standardized products can not only effectively improve the reliability of the equipment, but also greatly shorten the development cycle, providing extremely favorable conditions for the rapid modification and installation of equipment.

(3) Improve integration

. Select various large-scale and ultra-large-scale integrated circuits with strong functions and high integration, and try to reduce the number of components. The fewer components, the fewer potential hazards. In this way, not only can the reliability of the equipment be improved, but also the research and development cycle can be shortened.

(4) Derating design.

Derating design refers to the operation of components under conditions lower than their rated stress. It is an effective method to reduce the failure rate of components. Therefore, when designing, under the premise of ensuring technical performance indicators, the operating voltage range, temperature characteristics, electrical characteristic parameters, etc. of the components are all reduced, thereby reducing the failure rate of components under various stress conditions.

For derating design, different components have different factors to consider: some are voltage range, some are current size, some are temperature, some are frequency, some are vibration, etc. Generally speaking, the voltage, frequency and temperature characteristics of capacitors, the power of resistors, the current and frequency characteristics of inductors, the junction current, junction temperature or fan-out coefficient of diodes, triodes, thyristors, operational amplifiers, drivers, gate circuits and other devices, the voltage/current and temperature resistance of power switches and main power cables, the frequency characteristics of signal cables, and the use of heat sinks, connectors, module power supplies and other devices require derating design.

(5) Select high-quality components.

Components are the basic components of equipment, and their quality will directly affect the reliability of the equipment. Military communication equipment should try to use industrial-grade products or above, preferably military products, and strictly perform aging screening before installation to eliminate early failure devices.

(6) Make full use of software resources.

Due to the flexibility of software programming, software resources should be fully utilized in design. At present, there are relatively more software debugging methods and tools, which are easy to locate faults and design problems, and the solution cycle is relatively short. Making full use of software resources is an important method to improve reliability.

(7) Reliable structure, mature and advanced technology.

In circuit and structural design, the number of connectors and metallized holes should be minimized. Circuit components and chips should be directly soldered on the printed circuit board as much as possible. Surface mount components and surface mount technology should be used to avoid poor contact and ensure the reliability of the equipment.

(8) Thermal design.

Excessive temperature is one of the important factors that cause the performance and reliability of equipment to decrease. Therefore, thermal protection measures should be taken to control and reduce the temperature rise of the equipment during operation, ensure good heat dissipation, and improve the thermal reliability of the equipment.

Excessive low temperature will also cause the performance and reliability of the equipment to decrease. Some components cannot work normally when the ambient temperature is too low. Therefore, equipment used in low temperature environments must also be tested at low temperatures. The temperature conditions and environment of the equipment must be considered during design.

(9) Electromagnetic compatibility design.

When the equipment is working, it will be interfered by many electromagnetic fields, both natural and man-made. This is especially true for military equipment. In modern high-tech electronic countermeasures, a very important technical means is to locally emit high-energy electromagnetic waves to destroy the components in the opponent’s equipment, thereby causing the equipment to malfunction. To this end, effective shielding, filtering and other anti-interference measures should be taken to prevent noise and interference electromagnetic fields from interfering with the equipment and ensure the reliable operation of the equipment.

(10) Anti-vibration and impact design.

During use and transportation, the equipment will be affected by various vibrations and impacts, which will affect its reliability. Therefore, the mechanical strength and rigidity of the equipment should be improved, and vibration reduction and buffering measures should be taken to enhance the equipment’s ability to resist vibration and impact and improve the reliability of the equipment.

(11) Use fault indication device.

Design fault detection circuits and fault alarm devices to detect faults in time, thereby shortening the equipment’s fault repair time.

(12) Simple operation and convenient maintenance.

The operation and maintenance functions in the equipment are one of the main factors to ensure the reliability of the equipment. In the design, plug-in units and modules should be used as much as possible, and modular, standardized structures and quick disassembly structures should be used to facilitate operation and maintenance. Facts have proved that the modular structure of the equipment can greatly simplify operation and facilitate maintenance.