In the PCB board design, the engineers, the circuit design is the most basic. But many engineers are often careful in the design of complex and difficult PCB board, in the basic design of the PCB board but also ignore some of the places to pay attention to, and lead to errors. May make a perfect circuit diagram in the conversion into a PCB board when the problem is completely broken or broken. Therefore, in order to help engineers in the PCB board design to reduce design changes, improve work efficiency, in this proposed several in the PCB board design process to pay attention to aspects.

Design of Heat Dissipation System in PCB Board Design

In the PCB board design, the cooling system design includes cooling methods and cooling components selection, as well as the consideration of the cold expansion coefficient. PCB board is now commonly used methods are: through the PCB board itself heat, to the PCB board plus radiator and thermal conductivity board.

In the traditional PCB board design, the use of copper / epoxy glass cloth substrate or phenolic resin glass cloth substrate, there are a small amount of paper-based CCL, these materials, electrical performance and processing performance is good, but the heat Poor performance. As the current PCB design in the QFP, BGA and other surface mount components used in large quantities, the heat generated by components to a large number of PCB board, therefore, the most effective way to solve the heat is to enhance the contact with the heating element PCB board itself Ability to pass out or spread out through the PCB board.
PCB design _ thermal system design
Figure 1: PCB design _ thermal system design
When the PCB board has a small number of devices when the heat is large, the heating device in the PCB board to add heat sink or heat pipe; when the temperature can not come down, you can use a fan with a fan. When the amount of heat generated on the PCB board, you can use a large cooling cover, the overall heat sink on the component surface, so that it and the PCB board on each component in contact with the heat. For professional computers for video and animation production, even the need for water cooling way to cool.

Design and Layout of Components in PCB Board Design

In the PCB board design, no doubt face the choice of components. The size of each component is not the same, even if the same product manufacturers do not have the same characteristics of the production of components, so the PCB board design for the choice of components, suppliers must contact the characteristics of components, and Understand the impact of these features on PCB board design.

At present, the choice of the appropriate memory for the PCB board design is also very important point, due to DRAM and Flash memory constantly updated, PCB board designers to the new design from the memory market is a big challenge. So the PCB board designers must aim at the memory market, and manufacturers to maintain close contact.
PCB board design _ components overheating burned
Figure 2: PCB design _ components overheating burned

In addition, for some of the heat dissipation of the components must be necessary to calculate, their layout also need to consider, a large number of components together can produce more heat, causing the solder mask deformation separation, and even ignite the entire PCB board. So the PCB board design and layout engineers must work together to ensure that the components have a suitable layout.

Layout should first consider the size of the PCB board size. PCB board size is too large, the printed line length, impedance increases, anti-noise capacity, cost increases; PCB board is too small, the heat is not good, and adjacent lines vulnerable to interference. After determining the PCB board size, and then determine the location of special components. Finally, according to the functional unit of the circuit, all the components of the circuit layout.

Testability Design in PCB Board Design

Key technologies for testability of PCBs include: testability of testability, design and optimization of testability mechanisms, and processing and troubleshooting of test information. The testability design of the PCB is actually a testability method that can be easily tested to the PCB

, To provide access to the test object internal test information information channel. Therefore, the rational and effective design of the testability mechanism is successfully improved PCB board testability level of protection. Improve product quality and reliability, reduce the product life cycle cost, requires testability design technology to quickly and easily access the PCB board test feedback information, can be easily based on feedback information to make fault diagnosis. In the PCB board design, to ensure that DFT and other probe detection location and access to the path will not be affected.

With the miniaturization of electronic products, components of the pitch is getting smaller and smaller, the installation density will be more and more. The number of circuit nodes available for testing is less and less, and the on-line testing of printed circuit board assemblies is becoming more and more difficult. Therefore, the design of the PCB should take full account of the testable electrical conditions and physical and mechanical Conditions, the use of appropriate mechanical and electronic equipment for testing.
PCB design _ testability design
Figure 3: PCB design _ testability design

Sensitivity level in PCB board design
PCB board design _ humidity level
Figure 4: PCB design _ humidity level
MSL: Moisure Sensitive Level, that is, humidity sensitive level, in the moisture-proof packaging bags on the label, divided into: 1,2,2a, 3,4,5,5a, 6 eight grades. Components that have special requirements for humidity or are marked with a humidity sensor on the package must be managed effectively to provide a range of temperature and humidity control for the material storage and manufacturing environment to ensure the reliability of the temperature and humidity sensitive components. In the baking, BGA, QFP, MEM, BIOS and other requirements of vacuum packaging perfect, high temperature and non-high temperature components were baked at different temperatures, pay attention to baking time. PCB board baking requirements first refer to the PCB board packaging requirements or customer requirements. Baked after the humidity components and PCB board at room temperature can not exceed 12H, not used or not used at room temperature is not more than 12H humidity sensitive components or PCB board must be sealed with a vacuum or into the oven put.

More than four in the PCB board design to pay attention to the place, hoping to fight in the PCB board design engineers to help.