1. Preferably surface assembly and crimping components
Surface assembly components and crimping components, with good technology.
With the development of component packaging technology, most components can be purchased in a package category suitable for reflow welding, including plug-in components that can adopt through-hole reflow welding. If the design can achieve full surface assembly, it will greatly improve the efficiency and quality of assembly.
The crimping components are mainly multi-pin connectors. This kind of packaging also has good manufacturability and reliability of connection, which is also the preferred category.
2. Taking PCBA assembly surface as the object, packaging scale and pin spacing are considered as a whole
The packaging scale and pin spacing are the most important factors that affect the process of the whole board. On the premise of selecting surface assembly components, a group of packages with similar technological properties or suitable for paste printing of steel mesh of a certain thickness must be selected for PCB with specific size and assembly density. For example, mobile phone board, the selected package is suitable for welding paste printing with 0.1mm thick steel mesh.
3. Shorten the process path
The shorter the process path, the higher the production efficiency and the more reliable the quality. The optimal process path design is as follows:
Single-side reflow welding;
Double-sided reflow welding;
Double side reflow welding + wave welding;
Double side reflow welding + selective wave welding;
Double side reflow welding + manual welding.
4. Optimize component layout
Principle Component layout design mainly refers to component layout orientation and spacing design. The layout of components must conform to the requirements of the welding process. Scientific and reasonable layout can reduce the use of bad solder joints and tooling, and optimize the design of steel mesh.
5. Consider the design of solder pad, solder resistance and steel mesh window
The design of solder pads, solder resistance and steel mesh Windows determines the actual distribution of solder paste and the process of solder joint formation. It is very important to coordinate the design of welding pad, welding resistance and steel mesh to improve the pass rate of welding.
6. Focus on new packaging
The so-called new package, is not completely refers to the new package on the market, but refers to their own company has no experience in the use of those packages. For new package imports, small batch process validation should be performed. Others can use, does not mean that you can also use, the use of the premise must be done to understand the process characteristics and problem spectrum, master the response measures.
7. Focus on BGA, chip capacitor and crystal oscillator
BGA, chip capacitors and crystal oscillators are typical stress-sensitive components, which should be avoided as far as possible in PCB bending and deformation in welding, assembly, workshop turnover, transportation, use and other links.
8. Study cases to improve design rules
Manufacturability design rules are derived from production practice. It is of great significance for improving manufacturability design to continuously optimize and perfect the design rules according to the continuous occurrence of poor assembly or failure cases.