Via Aspect Ratio Be Used in Medical Devices

Creating a high-quality medical device requires careful layout to ensure signal integrity and long-term reliability. Numerous layout best practices can help with this, including using the largest vias possible and a proper aspect ratio. This will reduce fabrication issues and improve reliability while keeping cost under control.

Via aspect ratio is a relatively small factor that can have a big impact on PCB fabrication and design. Aspect ratio refers to the diameter of a plated through hole (VPH) in relation to its board thickness. The lower the aspect ratio, the more difficult it is to plate the interior of a VPH, and the harder it is to get a clean, consistent copper deposit. A lower aspect ratio also means that more of the hole’s copper will be exposed to the surrounding metallization, improving signal transmission and reducing impedance.

For example, a hole with an via aspect ratio of 10:1 would have a diameter of 0.02” and a depth of 0.062” – this is a very large hole for such a thin board, which can cause problems during manufacturing due to the difficulty of plating. Moreover, the extra thickness of the outer shell can increase the risk of cracking in z-axis expansion during soldering.

Can Via Aspect Ratio Be Used in Medical Devices?

The aspect ratio of a hole is also related to its material thickness, which is important because it has a significant effect on the coefficient of thermal expansion of the material. When the material is subjected to large temperature changes, such as during reflow, it lengthens along all axes. As a result, the larger a via’s aspect ratio, the more it can experience mechanical failure caused by the expansion of the copper inside. This can be particularly problematic for blind vias and buried vias, where any leftover via stubs can present inductive discontinuities that can impact signal integrity.

While it may seem like a trivial issue, the aspect ratio of a via is vital for the manufacture of a medical device, and should be carefully considered. In addition to the considerations mentioned above, it is also necessary to make sure that the aspect ratio of a hole does not exceed the maximum allowable value set by the IPC.

If the aspect ratio of a via is too high, it can create problems during manufacturing and compromise the quality of the finished product. To avoid these issues, you should consult a reputable PCB manufacturer for guidance on proper hole sizes and aspect ratios. Alternatively, you can use PCB layout software such as Altium Designer to help with figuring out appropriate via dimensions and annular rings. In addition, the software can assist you in implementing the best design practices to ensure signal integrity and long-term reliability. Talk to an Altium expert today to learn more about the benefits of using the software for your next project.

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