In the past, PCBs were relatively simple. However, new advancements in technology have made it possible to create complex boards that can do far more than their counterparts of the past. Multilayer PCBs are helpful when creating more advanced electronics.

The Multilayer PCB

A PCB is considered multilayer when it has three or more layers with conductive copper foil. The layers are circuit boards with two sides that have been laminated and then glued together. They also include insulation between the layers to help protect the boards from heat. The electronic connections that take place between the layers happen through vias. These might be blind vias, buried vias, or with plating through holes in the board. This allows for there to be more connections and can make for complex printed circuit boards.

The multilayer PCBs became essential when the need for more sophisticated electronics rose. The standard PCBs were not capable of handling the needs of the new electronics because there would often be issues with stray capacitance, crosstalk, and noise. The multilayer PCB can help to deal with those issues. The number of layers that are used in these boards will vary. Typically, applications will require between four and eight layers, but it depends on several factors.

Why Choose Multilayer PCBs?

These types of PCBs offer a range of benefits. One of the most common reasons for using the multilayer PCB is the size. Because of the layered design, it means that the PCB will be smaller than other printed circuit boards but still have the same level of functionality. Most people today want their electronics to be smaller, while still being powerful. The multilayer PCB allows for this. These types of boards also happen to weigh less, which helps to reduce the overall weight of the gadgets in which they are used. However, the size is certainly not the only benefit.

Typically, these boards will also be high-quality and very reliable. A lot of work goes into the design of the boards to ensure they will work. When combined with quality materials and construction, they can last. They are known for being durable, and a big part of this is the insulation layers that are between the board layers.

The connections on these boards are closer together than they are on standard PCBs. This means that they tend to be more connective and more powerful. They will have a greater capacity, as well as improved speed. The multilayer PCBs also have just a single connection point. This is helpful in the design of the final product in which they will be used. It will mean that the product only needs to have a single connection point. This allows for more design freedom for those gadgets.

These are some of the biggest benefits of multilayer PCBs. If you aren’t already considering using them for your next design, it might be time that you thought about it.

Common Real-World Applications for Multilayer PCBs

These types of boards are often considered the go-to type of printed circuit board to use because of the advantages mentioned above. They are found in many different types of consumer electronics, for example. They are used with smartphones, tablets, microwaves, smartwatches, computers, and much more.

Multilayer PCBs are also used in the telecommunications industry. They are often used for satellites, signal transmission, GPS, and towers. They are used in many industrial control systems, as well as in the automotive industry. Many vehicles today are heavily reliant on computer technology. These boards allow for complex electronics in a smaller space.

The boards are becoming common within medical industry electronics, as well. They are used for a range of different types of equipment that helps to diagnose and treat patients. Multilayer PCBs can be found in heart monitors, CAT scan equipment, and a host of other devices. The functionality, durability, small size and low weight help to make them a good solution for many military and aerospace applications, too.

As you can see, multilayer PCBs are the solution for just about any type of industry today. Above are just some of the different ways that they can be used. There are not any major disadvantages to using these types of boards. Even though there may be increased production time, this can be mitigated by finding a reputable company with a fast turnaround time.

Choosing the Right Manufacturing Company for Multilayer PCBs

When you are looking for a manufacturing company that can create the boards for you, it is important to ensure that they can handle all of the needed layers. Some of the companies available may not be capable of creating the number of layers needed for the boards you are creating. At Advanced Circuits, we have standard specs that can create 0 to 10 layers, and our custom specs can provide 0 to 40 layers. This should be more than enough for any multilayer PCB you might be designing.

When you choose Advanced Circuits, you will have more than just quality materials and the ability to create a large number of layers. You will find that our customer service helps to ensure that customers are happy from start to finish. We have a free software package that will make it easy for designers to create the boards they need and to test them to see whether they work before going ahead with a prototype.

We offer a fast turnaround time, great prices, and reliability. Additionally, you only have to order as many PCBs as you need, since we do not have a minimum. Get in touch today to learn more about how we can help.

Advanced Manufacturing Capabilities for Multilayer PCBs

There is a growing demand for more advanced printed circuit boards including multilayer PCBs and a growing need for smaller and lighter boards for many applications; from smartphones to medical devices and military equipment.  Advanced Circuits™ has made significant capital investments in the latest state-of-the-art equipment in its three U.S. based manufacturing facilities to offer advanced capabilities that include: oversized boards, heavy copper (up to 20 oz.), multilayer boards (up to 40 layers), laser drilled microvias, via-in-pad, microwave & RF boards, and much more.

Benefits of Multilayer PCBs

There are many benefits to using multilayer PCBs that design engineers can use to their advantage:

• Reduced circuit board space/weight
• Increased functionality
• High capacity/speed in a smaller footprint
• Higher assembly density
• connectors required for multiple PCBs reduced or eliminated

Advanced Circuit’s™ has many resources and the industry’s largest support team to help you meet your project requirements.  Click on the quick-links below for more information about our multilayer PCB manufacturing services:

• Full Capability Sheet [PDF]
• Pre-Preg Thickness Chart
• Controlled Impedance/Dialectic

Due to the physical attributes of these PCBs, size for a particular circuit or application may result in the need for large boards, or even the use of multiple boards. This is where the advent of technology and manufacturing techniques that permits fabrication of multilayer boards has been a major leap forward for application in electronic products.

Multilayer PCB Advantages

Utilization of multilayer printed circuit boards presents board design engineers and product developers with many strategic advantages:

Space requirements – creating printed circuit board designs with multiple layers means a considerable savings of real estate within the products that take advantage of the technology. Considering that adding layers generates only a slight increase in thickness of the resulting board (depending on the number of layers), the benefits over larger single or double-sided boards can be considerable. This is critical for modern electronic devices.

Weight – just as with space benefits, combining layers of components into a single multi-layer card can provide circuit functionality with a fraction of the weight over prior technologies. Think of the advantages when introduced for use in personal electronics, laptop computers, and flat-screen televisions.

Reliability – construction of multilayer board contributes to a high level of reliability and consistent performance.

There are Downsides to Multilayer PCBs

As critical as multilayer boards are in enabling the development of high-performance, compact electronic devices such as smartphones, military equipment, aerospace instrumentation, etc., there are trade-offs to be considered in their development and use:

• Cost – this is the primary consideration. With the specialized equipment required to manufacture multilayer PCBs, manufacturers must pass that cost to the customers, making the PCBs more expensive than traditional boards. Fortunately, as demand has increased and technology has evolved, this gap has narrowed considerably.
• Design tools – creating detailed technical designs for fabricators means that design engineers and layout technicians must transition to sophisticated software to aid in the design and manufacturing processes. This requires training and a learning curve for designers.
• Replacements – due to the structure and complexity of multilayer PCBs, repair of a failed board can be extremely cumbersome, if even possible. In most cases, a failed board results in the need to replace it, rather than attempt repair.

Fabrication Considerations for Multilayer PCBs

Fabrication of multilayer boards is not available from all PCB manufacturers. With the increasing percentage of boards designed with multilayer requirements, the number of producers is expanding. Although the process is relatively straightforward, specialized equipment and attention to detail is required. Training in the techniques is also required for efficient production as quality improves with experience.

Manufacturing processes include construction of layers of conductive material such as copper foil, core material, and prepreg layers, sandwiched together with heat and high pressure applied to laminate the layers together. Heat serves to melt and cure the prepreg materials, and the pressure removes air pockets that could impact board integrity.

These processes require specialized equipment and a significant commitment to operator training, not to mention the financial consideration. This explains why some fabricators have been slower to enter the multilayer manufacturing market than others.

Technology that Supports Design of Multilayer PCBs

A significant development that enables the creation and integration of multilayer boards into so many industries and products is the creation of extremely sophisticated software tools that are available to design engineers, layout specialists, and fabricators.

PCB design software facilitates computer aided design (CAD) that empowers circuit designers to increase efficiency, spot errors or problem areas quickly, and generate files for fabricators that are less likely to be problematic for the manufacturer. Even the design files can be analyzed for missing or incorrect content, avoiding traditional back-and-forth communications when manufacturing questions or issues arise.

Design for Manufacturing (DFM) applications aid both designers and fabricators through analysis functions that validate manufacturability of the resulting design. Without a DFM tool, PCB designs can made it to a fabricator to find the PCB will be either impractical, costly, or even impossible to build as designed.

Computer Aided Manufacturing (CAM) software is used by the manufacturer to validate and automate the actual fabrication processes.

Combined, these sophisticated tools make multilayer PCB design and manufacturing more efficient, streamlining the process from end-to-end. The result is more reliable, less costly multilayer boards, with improved project timelines.

Smartphones and computers are perfect applications for multilayer PCBs with their need for compactness and light weight, yet sophisticated functionality.

From a technical standpoint, there are numerous advantages to the use of multilayer designs, over and above saving space and weight:

• By incorporating multiple layers in a single PCB, boards can increase functionality.
• Manufacturing processes for multilayer boards result in high-quality, reliable end products.
• Multilayer boards by their innate electrical properties provide high capacity and high speed in a smaller footprint.
• Higher density of assembly
• Connectors required for multiple separate PCBs are reduced or eliminated, simplifying construction and further reducing weight.
• Multilayer PCBs can be manufactured in both rigid and flexible construction. Be advised though, that the more layers incorporated in a flex PCB, the less flexible it becomes.

Downsides of Multilayer PCBs

Every technology has pros and cons, and multilayer PCBs are not immune from negative attributes:

• Cost – one of the primary negatives in designing and implementing multilayer PCBs is the cost. As specialized processes are involved in the manufacturing of these boards, there is a considerable investment required for fabricators to offer these services. This makes the cost of multilayer boards higher than a traditional single or double-sided board.
• Service availability – not all PCB manufacturers have made the commitment to manufacturing these complex boards, limiting the resource options available to PCB designers.
• Compactness of multilayer boards generates design concerns for such issues as crosstalk and impedance problems.
• With increased functionality comes the need for more extensive testing of a single PCB. Manufacturing cycles may also be longer, due to the very complexity of the manufacturing process.
• Repairing a multilayer PCB can be extremely difficult, and may even be unfeasible or impossible. This makes failure of a multilayer board costly, since it may need to be totally replaced.
• Interconnection between layers is critical for board function, making design and fabrication of microvias and overall density critical.

Processes for Manufacturing Multilayer PCBs

Due to the sheer demand for multilayer PCBs for use in technology devices, healthcare equipment, military use, and even such consumer products as smart televisions and home monitoring equipment, most competitive manufacturers have positioned themselves to respond to the need for these boards.  There remains a mix of capabilities among fabricators related to volume production capabilities, and the number of PCB layers that can be produced.

Manufacturing of multilayer PCBs involves a process of combining alternating layers of prepreg and core materials into a single unit, utilizing heat and high pressure to ensure uniform encapsulation of conductors, elimination of air between layers, and proper curing of adhesives that bind the layers together.

Due to the multiple layers of material, execution of drill holes among layers must be carefully observed and registered. It’s important for successful manufacturing of multilayer PCBs that engineers incorporate symmetrical layout across layers, to help avoid twisting or bow in the materials when heat and pressure are applied.

When sourcing a fabricator for multilayer PCBs, it is critically important to acquire the manufacture’s capabilities and standard tolerances for these complex boards, and utilize design for manufacturing (DFM) techniques to accommodate those standards. This goes a long way toward building confidence that the result will meet all functional, reliability, and performance expectations.