8 basic principles of PCBA manufacturability design

1. Preferred surface assembly and crimp components

Surface-assembled components and crimp components have good processability. With the development of component packaging technology, most components can be purchased in a package category suitable for reflow soldering, including THT components that can be reflow soldered. If the design can achieve full surface assembly, it will greatly improve the efficiency and quality of assembly. Crimp components are primarily multi-pin connectors. These packages not only have good process and connection reliability, Also a preferred category to choose.

2. Taking the PCBA assembly surface as the object, considering the package scale and pin pitch as a whole

Package size and pin pitch are the biggest influence on the whole process. Under the premise of selecting surface-assembled components, it is necessary to select a set of similarly similar packages or suitable for a thickness of stencil for solder paste printing. Such as mobile phone board, the package what will be  selected is suitable for 0.1mm thickness stencil to solder paste printing.

3. Shorten the process path

The process path more short, the production efficiency will more high and the quality will more reliable. The preferred process path design is:

(1) Single-sided reflow soldering;

(2) double-sided reflow soldering;

(3) double-sided reflow soldering + wave soldering;

(4) double-sided reflow soldering + selective wave soldering;

(5) Double-sided reflow soldering + manual soldering.

4. Optimize component layout

Component layout design mainly refers to the layout and spacing of components. The plot of the components must fit with the requirements of the welding process. Scientific and reasonable layout, not only can reduce the use of bad solder joints and tooling, but also can optimize the design of steel mesh.

5. Overall consideration of pad, solder mask and stencil window design

The design of the pad, solder mask and stencil window determines the actual amount of solder paste dispensed and the formation of solder joints. Coordinating the design of pads, solder masks and stencils is a great effect on improving the FPY of soldering.

6. Focus on the new package

New package does not refer to the new package in the market, it’s your own company which isn’t have experience with. For the introduction of new packages, a small batch of process validation should be performed. What others can use does not mean that you can use it. The premise of using it must be to test, understand the process characteristics and problem spectrum, and master the countermeasures.

7. Focus BGA, chip capacitor and crystal

BGA, chip capacitors and crystal oscillators are typical stress-sensitive components. When laying out, the layout should be as close as possible to the place where the PCB is easily bent and deformed in the welding, assembly, workshop turnover, transportation, and use.

8. Research case perfect design rules

Manufacturability design rules are derived from production practices. Continuous optimization and perfect design rules based on emerging assembly failures or failure cases are of great importance for improving manufacturability design.