What are the ways and methods to improve the reliability of PCB equipment?

Date：2022-04-08 15:06:50Views：859

PCB reliability refers to the ability of "bare board" to meet the production conditions of subsequent PCBA assembly and maintain normal operation function in a certain period of time under specific working environment and operating conditions. 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.

In the scheme design, on the premise of ensuring that the equipment meets the technical and performance indicators, the design shall be simplified as much as possible, and the circuit and structure design shall be simplified to make each component the simplest design. Nowadays, the popular modular design method in the world is an effective measure to improve the reliability of equipment. The function of the block is relatively single, 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, and the modular design method should be adopted in product design.

(2) Use modules and standard components.

Modules and standard components are products that have been proved to be highly reliable after a large number of tests and extensive use, so they can fully eliminate the defects and hidden dangers of the equipment, and also bring convenience for replacement and repair after problems occur. The adoption 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 assembly of the equipment.

(3) Improve integration.

Select various large-scale and super large-scale integrated circuits with strong functions and high integration to minimize the number of components. The fewer components, the fewer hidden dangers. In this way, it can not only improve the reliability of the equipment, but also. It can shorten the research and development cycle.

(4) Derating design.

Derating design refers to that the components work under the condition of lower than their rated stress, which is an effective method to reduce the failure rate of components. Therefore, on the premise of ensuring the technical performance index, derating is adopted for the working voltage range, temperature characteristics and electrical characteristic parameters of components, so as to reduce the failure rate of components under various stress conditions.

In derating design, different components need to consider different factors: some are voltage range, some are current size, some are temperature, some are frequency, some are vibration and so on. In general, the withstand voltage, frequency and temperature characteristics of capacitor, the power of resistance, the current and frequency characteristics of inductance, the junction current, junction temperature or fan out coefficient of diode, triode, thyristor, operational amplifier, driver, gate circuit and other devices, the voltage / current and temperature resistance of power switch and main power supply cable, the frequency characteristics of signal cable, as well as radiator, connector The use of module power supply and other devices requires derating design.

(5) Select high-quality devices.

Components are the basic components of equipment, and their quality will directly affect the reliability of equipment. Military communication equipment should try to use products above industrial grade, preferably military products, and strictly carry out aging screening before putting on the machine 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 the design. At present, there are relatively many software debugging means 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 the circuit and structure design, the number of connectors and metallized holes shall be reduced as far as possible. The circuit devices and chips shall be welded directly on the printed board as far as possible. Surface mount devices and surface mount technology shall be adopted to avoid poor contact and ensure the reliability of the equipment.

(8) Thermal design.

Excessive temperature is one of the important factors that reduce the performance and reliability of the equipment. 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.

Too low temperature will also reduce the performance and reliability of the equipment. Some components can not work normally when the ambient temperature is too low. Therefore, the equipment used in low-temperature environment should also be tested at low temperature. The temperature conditions and environment of the equipment must be considered in the design.

(9) Electromagnetic compatibility design.

When the equipment works, it will be disturbed by many electromagnetic fields, both natural and man-made. This is especially true for military equipment. In the modern high-tech electronic war of resistance against Japan, a very important technical means is to locally launch high-energy electromagnetic waves to destroy the components in each other's equipment, so as to make the equipment work out of order. Therefore, effective shielding, filtering and other anti-interference measures shall be taken to prevent the interference of noise and electromagnetic field on the equipment and ensure the reliable operation of the equipment.

(10) Anti vibration and impact design.

The equipment will be affected by all kinds of vibration and impact in the process of use and transportation, which will affect its reliability. Therefore, the mechanical strength and stiffness of the equipment should be improved, and vibration reduction and buffer measures should be taken to strengthen the ability of the equipment to resist vibration and impact and improve the reliability of the equipment.

(11) Fault indication device is adopted.

The fault detection circuit and fault alarm device are designed to find the fault in time, so as to shorten the fault maintenance time of the equipment.

(12) Simple operation and convenient maintenance.

The function of operation and maintenance in the equipment is one of the main factors to ensure the reliability of the equipment. In the design, insert units and modules shall be used as much as possible, and modular, standardized structure and rapid disassembly structure shall be adopted to facilitate operation and maintenance. Facts have proved that the modular structure of the equipment can greatly simplify the operation and facilitate maintenance.

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