Microvias Impact Thermal Management in PCBs

A microvia is an interconnect hole in a printed circuit board that carries electrical signals from layer to layer. These tiny structures are one of the biggest drivers behind a shift toward smaller devices, precision, and high performance in today’s electronics landscape. Microvias can also create challenges for PCB designers, which is why it’s crucial to understand how they impact thermal management and to use them wisely.

Achieving the right balance between minimizing cost, manufacturing time, and reliability is the key to success when designing a PCB with microvias. The good news is that there are a few best practices to help you successfully incorporate these elements into your design and ensure they meet the demands of your application.

Before deciding to use microvias in your next design, you must first determine if they are manufacturable and work with your fabricator. The process of achieving these holes is not straightforward, and it’s essential to find a factory with the skills, technology, and experience necessary to reliably create these high-density interconnects (HDI).

How Do Microvias Impact Thermal Management in PCBs?

There are several methods for creating microvias in a PCB. Mechanical drilling is the most common, but this technique has many limitations when it comes to the type of via holes it can produce and its overall quality. Laser ablation, on the other hand, has become the go-to method for forming microvias due to its versatility and efficiency. In fact, this is now the only method used for forming Type 2 HDI boards, which require both buried and blind microvias.

When working with a fabricator that employs laser ablation to produce microvias, you’ll need to specify the exact diameter of each via’s capture pad and target pad in your PCB stackup. The manufacturer will then add a microvia fabrication allowance, which is the difference between these two numbers and must be sufficiently large to provide a reliable connection.

Another factor that impacts the reliability of a PCB with microvias is its copper plating thickness. If the thickness is too thin, it can lead to stress concentration at the via’s neck region. This happens because the via’s copper plating curves inward at its center, causing a pressure point at the center of the via barrel. This issue can cause the via to fracture under harsh conditions such as repeated thermal cycling or mechanical stress.

Finally, the dielectric material used in a PCB with microvias also plays an important role in its reliability. Using the lowest-cost option can negatively affect its performance over time and may lead to cracking, failures, or signal loss. The best way to avoid these issues is by choosing an advanced materials supplier with a track record of delivering superior products and exceptional customer service. The right partner will have the experience, knowledge, and resources to support your PCB design goals while offering competitive pricing. Contact JHYPCB for more information on how they can help your next project.