Advanced Circuits, Inc. (ACI)

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Printed Circuit Board Design and Microvias

Printed circuit boards are becoming smaller and smaller thanks to all the innovations in technology. It is possible to fit more into smaller spaces with the use of high density interconnect PCBs, as well as microvias.

Although microvias have been around for years, they are starting to become more common when multiple functions need to be controlled by a single board. The microvia routing between layers can make it easier to include all of the necessary functions.

Because all functions can be accomplished with a single board, it can help to save space in the equipment, and it could help to reduce some of the weight. While such a small weight reduction might not matter with some types of equipment, it can be quite important for equipment designed for the aerospace industry or the military.

What is a Microvia?

This is a much smaller version of a traditional via. To be considered micro, most feel that the diameter needs to be less than 150 micrometers (µm). These holes can be drilled with lasers or mechanically. Lasers, because of their precision, are becoming a preferred method of drilling these holes. Some can be as small as 15 micrometers.

Lasers also have the benefit of not leaving behind any residue or materials in the drilled holes, which could happen with a mechanical drill. There tend to be fewer defects with lasers, as well. However, a quality manufacturer that knows and understands how to properly drill the microvias mechanically will have a low instance of failures, as well.

Today, there are several different types of microvias. Regardless of the type, you will find that they all have two characteristics in common that will need to be considered. They are going to have a low aspect ratio, and there may be a risk of fracture in the neck region. This fracturing could happen due to mechanical shock, vibrations, or because of the thermal cycling.

Buried Microvias

A buried microvia will only span between two interior layers. They will not reach the outer part of the circuit board. Many designers will span a single layer using these types of microvias, which can help to make fabrication easier and help to increase the reliability of the vias.

Blind Microvias

Blind microvias will start at the surface layer of the board and then go one to two layers below the surface before terminating. Most designers will have a blind microvia that spans just a single layer. Those who need to span two layers may want to use stacked microvias instead.

Stacked Microvias

The stacked microvias are “stacks” of buried vias or a blind microvia that has been stacked atop buried microvias. This is a common way to span multiple layers in the printed circuit board while helping to improve reliability and reducing the number of fabrication steps needed. It is important to note that internal buried microvias that are in the stack should be filled with conductive paste and then plated over. This helps to provide a strong contact for the next via in the stack.

Microvias Offer Many Benefits

Many companies today are using these types of vias because they need to have more components packed into smaller spaces. As mentioned, this helps to reduce the size of the board, meaning it can fit into smaller equipment.

However, smaller boards can also often result in cost savings. The use of microvias-in-pad allows for connections to be made in the pads of various types of surface-mounted technologies. Normal vias are often too large for the surface-mounted technologies, so this helps to ensure a better fit inside of the pad without needing to worry about manufacturing problems. There are plenty of reasons to choose to use microvias. However, you also need to be sure that they can be manufactured properly.

Fabrication Should Be Entrusted to the Right Manufacturer

Microvia fabrication can be complex, and this means that not all of the manufacturers offering these services are capable of providing you with what you need. You need to make sure that you are always working with the best manufacturers in the field, such as Advanced Circuits. We have the technology, the tools, the experience, and the facilities to handle all manner of PCB fabrication needs, including microvias.

Other Reasons to Choose Advanced Circuits

Advanced Circuits has many features that help to make us a standout company for creating all of your printed circuit boards. One of the biggest benefits is the free software that we offer. This software makes it easy for designers to create the ideal boards for their needs. They can experiment with the designs. They can use various types of vias and microvias and other features. You can test it all out virtually before committing to getting a prototype or going into full production. Our experts will review the engineering file before it goes into production, as well, to ensure there are no errors that will need to be fixed.

We’re the third-largest printed circuit board manufacturer in the United States and we work hard to ensure the best possible customer service. Advanced Circuits has a reputation for being reliable and for providing high-quality fabrication of PCBs. We offer around-the-clock tech support, so users can always get in touch by phone with a live person at Advanced Circuits.

We offer instant quotes, order status tracking, and extremely fast turnaround time. Additionally, there are not any minimum PCB order requirements as you might find with other companies. This means that if you are just in need of a prototype or a handful of boards, you can get just what you need. If you need thousands of PCBs, we can do that, as well.

Create Your Board Today

If you are intrigued by the benefits that can be found with microvias and you feel that they could be what your PCBs need, it’s time to get started. Use our software to build your board, test it out, and see whether it’s the right solution for your needs.


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