PCBA manufacturability design, not only can be made to solve problems, to solve the problem of low cost and high quality of manufacture. But the "manufacturing" and "low cost and high quality" the achievement of goals, not only depends on the design, also depends on manufacturing, but more depends on the coordination and unification of the design and manufacture, namely the design of "integration". Understanding this is very important, is the foundation of PCBA manufacturability design. Only realize this, we can systematically and comprehensively grasp the PCBA manufacturability design.
In most of the SMT discussion, when it comes to manufacturability design, basically is the optical position symbol design, transmission design, assembly design, space design, welding plate design, and so on, these are some of the design of "elements", but the core is how these elements "coordination and unity". If you don't know it, even if all the design meets the requirements, will not have the desired effect.
In the manufacturability design of PCBA, the assembly mode of PCBA is generally determined according to the number of components in the hardware design material list (BOM) and the package, that is, the layout of components on both sides of PCBA, which determines the process path during assembly, so it is also called process path design. Then, the components are arranged according to the welding process method adopted on each assembly surface. Finally, according to the packaging and technological methods to determine the spacing between components and stencil thickness and window graphic design.
1. Packaging is the basis and starting point of manufacturability design
As can be seen from the above figure, packaging is the basis and starting point of manufacturability design. Regardless of process path, component layout, solder pad, component spacing and stencil window, packaging is carried out around packaging, which is the bridge connecting design elements.
2. The welding method determines the layout of components
Each welding method has its own requirements for the layout of the components. For example, the wave-soldering element requires that its long direction is perpendicular to the transmission direction during PCB wave-soldering, and the spacing is greater than the height of the component with higher adjacent components.
3. Packaging determines the matching of the welding disc and stencil window
Encapsulation process characteristics, decided to need to the amount of solder paste and distribution. Encapsulation, solder and are related and influence of the steel net, welded plate and pin structure determines the morphology of the solder joints, also determines the ability of adsorption molten solder. Steel mesh window and thickness design determines the amount of solder paste printing, in the design of bonding pad must be associated with a window of the stencil and packaging requirements.
4. Manufacturability design and SMT process determine the yield of manufacturing
Manufacturability design provides the prerequisite and inherent process capability (Cpk) for high quality manufacturing, which is one of the reasons mentioned in the quality management course "design determines quality".
These views or logical relations are the embodiment of the inner connection of manufacturability design, which must be remembered in the design of manufacturability in order to carry out the design of manufacturability with the idea of "integration".