<h1>HDI PCB Design Best Practices</h1> <h2>Overview</h2> <p>High-Density Interconnect (HDI) PCBs represent cutting-edge technology enabling smaller, faster, and more powerful electronic devices.</p> <h2>Core Design Principles</h2> <h3>1. Layer Stack-Up Planning</h3> <ul> <li>Use sequential lamination for complex designs</li> <li>Implement 1+N+1 or 2+N+2 stack-up structures</li> <li>Place signal layers adjacent to reference planes</li> <li>Symmetrical stack-up to minimize warpage</li> </ul> <h3>2. Microvia Design (2025 Standards)</h3> <ul> <li>Diameter: ≤150 μm for standard HDI, ≤100 μm for ultra-HDI</li> <li>Aspect ratio: ≤1:1 for reliability</li> <li>Limit depth to 1-2 layers maximum</li> <li>Pad size: 0.25-0.30mm</li> </ul> <h3>3. Via-in-Pad Technology</h3> <ul> <li>Direct laser drilling on component pads</li> <li>Copper plating and planarization</li> <li>Essential for BGAs with pitch ≤0.8mm</li> </ul> <h3>4. Trace Width and Spacing</h3> <ul> <li>Minimum: 2 mil (0.05mm)</li> <li>Controlled impedance requires precise geometry</li> <li>Differential pairs: match lengths within 5 mil</li> </ul> <h3>5. DFM Guidelines</h3> <ul> <li>Consult manufacturer for capabilities</li> <li>Provide detailed stack-up specifications</li> <li>Design for electrical testability</li> </ul> <h2>Applications</h2> <ul> <li>Consumer electronics (smartphones, wearables)</li> <li>High-performance computing</li> <li>Medical devices</li> <li>Aerospace and defense</li> </ul> <hr> <p><em>Based on industry best practices from <a href="https://www.allpcb.com/blog/pcb-knowledge/hdi-pcb-stackup-mastering-layer-configuration-for-optimal-performance.html">AllPCB</a>, <a href="https://www.tessolve.com/blogs/high-density-interconnect-hdi-pcb-design-best-practices-for-complex-products/">Tessolve</a>, and <a href="https://resources.pcb.cadence.com/blog/2024-hdi-pcb-design-guidelines-with-orcad-x">Cadence</a></em></p>