PCB Reliability - Micro Vias vs Stacked Vias
Printed Circuit Boards (PCBs) are an essential component in electronic devices, and their reliability is a critical aspect to ensure the longevity and functionality of the device. Two common types of vias used in PCBs are Micro Vias and Stacked Vias. While both types of vias serve the same purpose, they have different applications and reliability.
Micro Vias
Micro Vias are small diameter vias, usually less than 0.15mm in diameter, and they are used in high-density PCBs. They are drilled using laser technology and are beneficial in decreasing the overall PCB size because of their smaller size. Micro Vias also have a shorter aspect ratio, which reduces the possibility of drilling-related defects.
However, Micro Vias have a lower reliability compared to Stacked Vias because of their smaller size. They are prone to failures like cracking and fracture, which can significantly affect the functionality of the device. In addition, Micro Vias are not ideal for high current applications due to their lower current-carrying capacity.
Stacked Vias
Stacked Vias, as the name suggests, are a series of consecutive vias stacked together vertically. They are larger in diameter, and their aspect ratio is higher than Micro Vias, making them suitable for high current applications. Stacked Vias also offer higher reliability due to their larger size and are better suited for harsh environments because of their interconnect capabilities.
However, Stacked Vias have their drawbacks. They are more expensive and take up more space compared to Micro Vias. Stacked Vias may also have issues with thermal stress and can cause cracking in PCBs.
Comparison
| Aspect | Micro Vias | Stacked Vias |
|---|---|---|
| Reliability | Lower compared to Stacked Vias | Higher due to size |
| Current-carrying capacity | Lower | Higher due to size |
| Size | Smaller and suitable for high-density PCBs | Larger and suitable for high current applications and harsh environments |
| Cost | Cheaper | More expensive |
| Thermal stress tolerance | Higher likelihood of failure | May cause board cracking |
Conclusion
Both Micro Vias and Stacked Vias have their advantages and disadvantages. The choice between the two should depend on the application and reliability required. For high-density PCBs, Micro Vias are an excellent option because they save space and are cheaper. On the other hand, Stacked Vias are ideal for harsh environments and high current applications.
Reference
- Epec Engineered Technologies. (2021). Micro Vias vs Stacked Vias: Which to Use & Why? [online] Available at: https://blog.epectec.com/micro-vias-vs-stacked-vias.