PCB Tech - What is the hazard of holding the PCB board with one hand?

What are the reasons for PCB board welding defects?

1. The solderability of the PCB circuit board holes affects the quality of soldering. The poor solderability of the PCBA circuit board holes will cause virtual soldering defects, which will affect the parameters of the components in the circuit, resulting in unstable conduction of the components and the inner line. Cause the entire circuit function to fail.

2. Welding defects caused by warpage, PCB circuit boards and components warped during the welding process, and defects such as virtual welding and short circuit due to stress deformation. Warpage is often caused by the temperature imbalance of the upper and lower parts of the circuit board., For large PCBs, the PCB will warp due to the weight of the board itself.

3. The design of the PCB circuit board affects the welding quality. In the design, the circuit board size is too large, although the welding is easier to control, but the printed line is long, the impedance increases, and the cost increases.

If it is too small, the heat dissipation will decrease and the welding will not be easy to control. It is easy for adjacent lines to interfere with each other, therefore, the PCB board design must be optimized.

a. Shorten the connection between high-frequency components to reduce EMI interference, b. Heavy weight components should be fixed with brackets, and then welded, c. Heat dissipation issues should be considered for heating components, and heat-sensitive components should be far away from heat sources, d. The arrangement of the components is as parallel as possible. The PCB is not only beautiful but also easy to weld, so it is suitable for mass production.

In the process of dip plug-in and soldering of the circuit board PCB, smt chip processing manufacturers have many employees or customers involved in operations, such as plug-in component insertion, ICT testing, PCB sub-boarding, and manual soldering operations on the PCB board., Install screws, install rivets, manually press in crimp connectors, PCBA circulation, etc. During this series of operations, a common action is to hold the circuit board alone, which is the one that causes the failure of BGA and chip capacitors. The main factor is what are the hazards of holding the PCB board with one hand on the PCB circuit board.

(1) Holding the PCB board with one hand, for those circuit boards with small size, light weight, no BGA, and no chip capacitance, it is generally allowed, but for those circuits with large size and heavy weight, BGA and chip capacitors are laid out on the side. Boards should be avoided, because such behavior can easily cause the solder joints of BGA, chip capacitance and even chip resistors to fail. Therefore, in the process documents, the requirements for how to take the circuit board should be specified.

The link that is prone to hold the PCB board with one hand is the circulation process of the circuit board. Regardless of whether the board is taken from the belt line or the board is placed, most people will unconsciously use the method of holding the board with one hand because it is smooth. When manually soldering, attaching heat sinks, and installing screws, because of the need to complete an operation, it is natural to hold the circuit board in one hand and operate other work items in the other. These seemingly normal operations often hide great quality risks.

(2) Install screws. In many smt chip processing factories, in order to save costs and eliminate tooling, when installing screws on PCBA, they are often deformed due to the unevenness of the components on the back of the PCBA, which are easy to make which are sensitive to stress. The solder joints are cracked.