PCB Design Principles

PCB Design Principles

1. Prefer Surface-Mount and Crimped Components

Surface-mount (SMD) and crimped components offer excellent manufacturability.

With advancements in component packaging, most parts are now available in reflow-compatible formats—including through-hole components compatible with reflow soldering. A fully surface-mounted design significantly enhances assembly efficiency and quality.

Crimped components, primarily multi-pin connectors, also provide strong manufacturability and connection reliability, making them a preferred choice.

2. Shorten the Process Path

A shorter process path improves production efficiency and quality reliability. The recommended process hierarchy is:

  • Single-sided reflow soldering
  • Double-sided reflow soldering
  • Double-sided reflow + wave soldering
  • Double-sided reflow + selective wave soldering
  • Double-sided reflow + manual soldering
3. Optimize Component Layout

Component placement should consider orientation and spacing to meet soldering requirements. A well-planned layout reduces defective solder joints, minimizes tooling dependencies, and optimizes stencil design.

4. Coordinate Pad, Solder Mask, and Stencil Design

The pad geometry, solder mask openings, and stencil fenestration determine solder paste volume and joint formation. Aligning these elements improves first-pass yield in soldering.

5. Evaluate New Package Types

“New” packages refer to those unfamiliar to your production team—not necessarily the latest on the market. Before full adoption, conduct small-batch process validation to understand their characteristics, failure modes, and mitigation strategies.

6. Handle Stress-Sensitive Components with Care

BGAs, chip capacitors, and crystal oscillators are highly sensitive to mechanical stress. Avoid placing them near PCB areas prone to bending during soldering, handling, or operation.

7. Refine Design Rules Through Case Studies

DFM guidelines evolve from real-world production data. Continuously analyze assembly defects and failures to optimize design rules for better manufacturability.