How to improve the reliability of PCB equipment
Technical measures to improve the reliability of PCB equipment: plan 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, on 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 structure design should be simplified so that each component becomes the simplest design. Modular design methods popular in the world today are effective measures to improve equipment reliability. The function of the block is relatively single, and the system consists of modules, which can reduce the complexity of the design and standardize and standardize the design. A large number of domestic and foreign facts have proved this, and the 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 extensive testing and extensive use, which can fully eliminate equipment defects and hidden dangers, and also facilitate 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, and provide extremely favorable conditions for the rapid modification and installation of the equipment.
(3) Improve integration.
Choose various large-scale and ultra-large-scale integrated circuits with strong functions and high integration to minimize the number of components. The fewer components there are, the fewer points of potential hazards. In this way, not only can the reliability of the equipment be improved, but also. Can shorten the research and development cycle.
(4) Derating design.
Derating design refers to the working of components under their rated stress, which is an effective method to reduce the failure rate of components. Therefore, the design of the components under the premise of ensuring technical performance indicators, the operating voltage range of components, The temperature characteristics and electrical characteristics parameters are all derated to reduce the failure rate of components under various stress conditions.
Derating design, different components have different factors to consider: some are voltage range, some are current, some are temperature, some are frequency, some are vibration, etc. In general, the voltage, frequency, temperature characteristics of capacitors, the power of resistors, the current and frequency characteristics of inductors, the junction current, junction temperature, or other components of diodes, transistors, thyristors, operational amplifiers, drivers, gate circuits, or Fan-out factor, voltage / current and temperature resistance of power switch and main power supply cable, frequency characteristics of signal cable, and the use of radiators, connectors, module power and other components require derating design .
(5) Select high-quality devices.
The component is the basic unit of the equipment, and its quality will directly affect the reliability of the equipment. Military communication equipment should use industrial-grade or higher products, preferably military products, and perform aging and screening before the machine is used to eliminate early failure devices.
(6) Make full use of software resources.
Because of the flexibility of software programming, software resources should be fully utilized in the design. At present, there are relatively many software debugging methods and tools, and it is easy to locate faults and design problems, and the solution period is relatively short. Making the most of software resources is an important way to improve reliability.
(7) Reliable structure, mature and advanced technology.
In the design of circuits and structures, the number of connectors and metallization holes should be reduced as much as possible. Circuit devices and chips should be soldered directly on the printed board as much as possible. Surface-mount devices should be selected and surface-mount technology should be used to avoid poor contact. To ensure the reliability of the equipment.
(8) Thermal design.
Excessive temperature is one of the important factors that cause the performance and reliability of the equipment to decrease. To this end, thermal protection measures should be taken to control and reduce the temperature rise of the equipment during operation, ensure a good heat dissipation setting, and improve the thermal reliability of the equipment.
Too low temperature will also cause the equipment performance and reliability to decrease, and some components may not work properly when the ambient temperature is too low. Therefore, equipment used in low temperature environments should also be tested at low temperatures. The temperature conditions and environment in which the equipment operates must be considered in the design.
(9) Electromagnetic compatibility design.
The equipment will be interfered by many electromagnetic fields when working, there are natural and artificial. This is especially true for military equipment. In modern high-tech electronic confrontation warfare, a very important technical means is to locally emit high-energy electromagnetic waves to destroy the components in the opponent's equipment and cause the equipment to malfunction. To this end, effective shielding, filtering and other anti-interference measures should be taken to prevent noise and interference from interference of electromagnetic fields on the equipment and ensure that the equipment works reliably.
(10) Anti-shock design.
The equipment will be affected by various vibrations and shocks during use and transportation, which will affect its reliability. To this end, the mechanical strength and stiffness of the equipment should be improved, and vibration damping measures should be taken to strengthen the equipment's resistance to vibration and shock. The ability to improve the reliability of the equipment.
(11) adopts fault indication device.
Design fault detection circuit and fault alarm device, in order to find the fault in time, thereby shortening the troubleshooting 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, plug-in units and modules should be used as much as possible, and at the same time, a modular, standardized structure and a quick disassembly structure are used to facilitate operation and maintenance. Facts have proved that the modular structure of the equipment can greatly simplify operation and facilitate maintenance.