The quality of the Pcb assembly craft involves five aspects: “human, machine, material, link, and method”. If the quality of these “entries” fluctuates greatly, then establishing a high-quality, repeatable craft is an empty talk.
Many pcb manufacturers use multi-brand electronic materials in order to reduce the procurement cost of electronic manufacturing and avoid risks which is a big hidden danger for the pcb craft. Materials of different brands, especially those with a low degree of standardization, often have different weights and different pin widths, which are often factors that cause craft instability. Therefore, in order to create a first-class craft, it is necessary to systematically think and control the system from the aspects of material selection, craft design, craft trial manufacturing, craft optimization, and quality monitoring.
In view of the above recognition, the characteristics, common causes and improvement measures of circuit board quality defects must be recognized that "a single craft problem may have multiple causes, the same cause may lead to different defects", before taking measures should locate the problem accurately, verify the measures, and do not blindly copy; also should realize that many pcb craft measures have "two-sidedness", for example, to reduce the bridging connection of the dense components, use a thin steel mesh, but will add the probability of open soldering of components with poor coplanarity of large pins, therefore, weigh and evaluations must be made before taking measures.
The causes of some craft problems are sometimes difficult to define due to design problems, material problems or operational problems. Sometimes they change among them, and they can often be solved from different aspects. For the cause of such problems, it can be said t A reason or B reason. For example, the screw around the BGA is easy to cause the BGA solder joint to break. It can be said design problem or operation problem.