Building models doesn’t seem to captivate young people as much as it has in the past. History, engineering, and best assembly practices are just a few things that I learned from the satisfaction of building models. Another important lesson was in how to apply paint best. Rushing the painting process, which should happen in stages, risked producing a messy looking model. Evenly applying the paint in multiple coats achieves a remarkably realistic look and texture.
Many processes besides painting benefit from the expert application of multiple layers, especially printed circuit boards. Indeed, you can lower the cost of a PCB if you design it as a double-sided board, but you may strangle its performance by doing so. Using multiple board layers can increase electrical performance to outweigh the differences in cost. Here are some of the advantages of multilayer PCBs and how you can best benefit from them.
Multilayer PCBs Open Up Space to Work with on the Board
The main benefit of multilayer circuit boards is the extra layers opening up additional real estate. You’ll shift signal and power traces to internal layers where there’s more room for direct connections, without winding the traces around exterior components and other obstacles. With the extra room freed on the board’s external layers, you’ll have space for additional components and their associated circuitry.
Another space-saving benefit uses solid metal plane layers instead of routing power and ground nets with wide traces. On single or double-sided boards, power and ground are routed with wide traces to allow for the regular signal trace routing. Some boards have a full or partial plane on the top or bottom of the board to help with EMI, thermal, and other considerations, but most rely on internal power and ground planes for their PDN. Much of the trace routing on a circuit board is done in conjunction with the different plane layers to provide clear signal return paths and maintain signal integrity.
Better Performance is One of the Most Important Advantages of Multilayer PCBs
There are many reasons to use a multilayer board rather than just saving space. Multiple layers in your PCB solve electrical performance issues, including the following:
- EMI Shielding: With a multilayer board, you can configure the layer structure to include multiple ground planes. The planes shield against incoming electromagnetic interference that can abuse the board’s circuits and stop any outgoing EMI emissions.
- Signal integrity: Multilayer boards can be configured with microstrip or stripline layer structures to sandwich high-speed transmission lines between them. These structures will provide better signal return paths, reducing noise on the board and controlling crosstalk and broadside coupling between signal traces.
- Power integrity: Full metal power and ground planes offer a better method of distributing power and ground than routing them with traces. The planes also help absorb the power spikes that occur with high-speed circuit switching, providing a cleaner power distribution network (PDN).
- Thermal control: Many components on a circuit board will run hot and require additional cooling methods. The multilayer board structure can help with this by dissipating the heat throughout the board layer stackup.
Another benefit to a multilayer board stackup is in the fabrication of the board. With more room, the circuitry balances across the board as well as through its layers. Designers can then balance the copper weight of each layer with its mirror layer. For instance, a four-layer board’s goal is to have the two outer layers configured with similar copper weights and traces for balance, while the two inner layers should be similarly balanced. Consistency will reduce the chance of the board “potato chipping” or curling during manufacturing. Trying to achieve balance on a two-sided board can be much more difficult if one layer is devoted to a solid plane while the other is not.
Many decisions present themselves when configuring the best layer stackup for your circuit board for its performance and manufacturing. Here is where working with experts can make a big difference to the success of your project.
For the Best Results, Consult the Multilayer PCB Experts
Adding layers to a board layer stackup will cost additional money, averaging between $25 to $50 per layer pair on a typical sized board. The increase justifies itself with the expected increase in performance, manufacturability, and even additional circuitry that a multilayer board will offer. Your local PCB contract manufacturer can help you understand these decisions’ potential benefits toward the most informed choice.
At VSE, we’ve been working with design engineers like you for over 30 years and understand the choices you’re considering when configuring your PCB design. We can help you with questions about balancing out the layers in your board layer stackup, as well as how the configuration of a multilayer board will impact the signal and power integrity of your design. We have a wealth of experience engineering and building many circuit boards, and our engineering team is ready to work with you.
