Common causes of poor design and SMB phenomenon Analysis

In the SMB design stage, if not fully take into account the manufacturing process requirements, resulting in the manufacturing process of the poor, to correct in the manufacturing process, there is a problem, it will waste hours delay period, they can not guarantee the quality of products; poor general design issues and, in production stage is difficult to overcome. Here are some common reasons for SMB design and produce undesirable phenomena.
1) Design of SMB no edge technology, process shaped hole or shape or size too big / too small, which is due to insufficient understanding of surface mount technology equipment, lead to the design of the SMB can not meet the requirements of the equipment setup, not mass production.
2) via the pad: when the result after the solder is melted by welding via the drain to the bottom, the solder joints is too small, welding unreliable. This is due to the designer of the reflow soldering process equipment enough to understand. SMT solder reflow soldering is distributed beforehand on the pad, solder melting connect components and PCB pad welding, when the PCB pad with a hole melted solder will flow through the lower hole, it is not a hole on the pad when the pad over the line must be drawn pad hole and then over the line.
3) chip component pad size asymmetry, especially land line, over the line as part of the pad to use, so that when the reflow chip components at both ends of uneven heating pads, solder melting has caused tombstoning.
Cause of the defect is part of the enterprise lack of a unified design specifications, good corporate design for manufacturing standard design is based on SMT process requirements, and the development of the enterprise status quo out of SMT equipment and continuous improvement.
Conclusion
Because of small surface mount components to meet the requirements of high density and automated assembly equipment, enabling miniaturization of electronic products, the volume, the development of a variety of functional requirements and accelerate the replacement frequency of reality, to promote the Surface Mount Technology unstoppable trends, design for manufacturability and therefore more and more integrated into the design of the PCB, which emphasizes the problems that may occur during the manufacturing process to advance to the design stage to resolve. Good PCB design for manufacturing can effectively control costs, shorten product development cycles, improve the market competitiveness of products.