How to see if the PCB board is good or bad?

With the rapid development of mobile phones, electronics, telecommunications and other industries, the PCB circuit board industry has developed rapidly. People demand more and more layers, weight, precision, materials, colors and component reliability.
However, due to fierce competition in market prices, the cost of PCB boards is also on the rise. More and more manufacturers monopolize the market at low prices to enhance their core competitiveness. However, behind these ultra-low prices is to reduce material costs and production costs, but equipment is often prone to cracks (cracks), scratches (or scratches), and its comprehensive factors such as accuracy and performance do not meet the standards, seriously affecting the products used. Solderability and reliability.
Faced with various PCB boards on the market, there are two ways to distinguish the quality of the PCB board. The first way is to judge from the appearance, and the other method is judged from the quality specifications of the PCB board itself.
PCB board
How to judge the quality of the PCB board:
First: distinguish the appearance quality of the PCB
In general, the appearance of a PCB board can be analyzed and judged from three aspects.
1. Standard rules for size and thickness.
The thickness of the PCB is different from the standard PCB. Customers can measure and inspect according to the thickness and specifications of the product.
2. Light and color.
The external circuit board is covered with ink, and the circuit board can be insulated. If the color of the circuit board is not bright, the ink is small, and the insulating board itself is not good.
3. Welding appearance.
Because there are many PCB components, if the soldering is not good, the components are easily detached from the PCB, which seriously affects the soldering quality of the PCB, good appearance, careful identification, and a powerful interface is very important.
Second: high quality PCB boards need to meet the following requirements
1. After the components are installed, the telephone is required to be used well, that is, the electrical connection should meet the requirements;
2. The width, thickness and distance of the line meet the requirements to avoid line heating, open circuit and short circuit.
3. When exposed to high temperatures, the copper skin is not easily peeled off.
4. The copper surface is not easily oxidized, which affects the installation speed. It will be damaged soon after oxidation.
5. No additional electromagnetic radiation;
6. The shape is not deformed to avoid deformation of the housing and misalignment of the screw holes after installation. All are now mechanized installations. The hole position of the board and the distortion of the circuit and design should be within the allowable range.
7. High temperature, high humidity and special environmental tolerance should also be considered.
8. The mechanical properties of the surface should meet the installation requirements.