Tips for Creating the Best PCB Layer Stackup

When I first started building projects in and around my house, I learned very quickly to consult the experts when it came time to select my materials. For instance, the instructions for a tool shed that I built specified a certain roofing material that was pretty expensive. After asking at my local home improvement store I found out that for our climate, the ultra-robust roofing material listed wasn’t needed and was, therefore, more expensive than the standard materials.

When you are creating the PCB layer stackup on your board design you will probably run into a similar scenario. You may not know the best PCB materials to use or how to effectively construct the stackup. It will be in your best interest to understand what you need before you commit to anything. Optimizing your design means sorting through hordes of variables to consider and choose from. I can’t tell you what you should do, but let’s take a look at some of the ways that you can find out what you need to know about PCB layer stackups before you proceed with your design.

Work with Your Manufacturer for the Best PCB Layer Stackup

One of the best sources of information that you can leverage when creating a PCB layer stackup is that of your board manufacturer. They will be able to work with you to figure out what you are trying to do with your board design, and then tell you the specifics of what you will need to successfully fabricate it.

When first setting up your board, consider the many different parameters and make sure to give your manufacturer as much information as possible about the board you are designing. For instance, you will want to tell them the following:

• Purpose of the board: Knowing what the board is supposed to do will help them when they make their evaluation of what materials and stackup should be used. On the same hand, knowing in what environments the board will live will alter what materials will be best suited. High-moisture environments could alter a design entirely.

• Board technology: They will want to know what kind of parts are being used, and whether or not the board will have high speed circuits on it. High speed designs may require different materials and/or unique board layer stackups signal performance.

• Board size: The manufacturer will want to know what size the board is in order to determine what panel size will be needed for manufacturing. Not only is it more cost effective to maximize the number of individual boards that can be put into a panel, but it will affect how the board layer stackup is created and what materials will be used.

• Cut-outs, holes, and special features: Like the board size, this information could make a difference in what the manufacturer decides is the best way to go in setting up your board for fabrication and assembly. Drill hole files and information for plated through-hole (PTH) or non-plated through-hole (NPTH) will also be helpful for your manufacturer.

There is a lot more information that your manufacturer will need, and they will present you with a complete set of questions on your design so that they are as prepared as possible. The important thing is to work with them early so that you can start the design in the right direction.

The last thing you want to do is to have to do a major redesign because the manufacturer can’t make a board layer stackup the way you devised it. As it has been said, “Design your board according to the way that the manufacturer has specified it be done instead of how you think it should be done. This is what these people do every single day for a living, and they are good at it!”

Your manufacturer will be a great resource for complex PCB layer stackup information

PCB Design Resources and Help are Out There—Use Them

As I mentioned, your PCB manufacturer will be the first best resource to go to for information on how to create your board layer stackup. There are, however, many other resources that you should look into as well for a helping hand. If you are working for a company that has been designing boards, find out what they have been doing for similar designs. Also, seek out help for those you work with, and don’t be afraid to consult blogs and white papers for information as well. That is what they were written for.

Another good resource to use is online impedance calculators and layer stackup generators. Many printed circuit board fabricators have these available for you to use, and they can be a big help. You can also find additional information on layer stackups from organizations such as IPC.

The Cross Section Editor in OrCAD PCB Designer is a great tool for creating stackups

PCB Design Tools that Can Help You Work with PCB Layer Stackups

Once you’ve decided on what kind of board you are designing, and you’ve consulted with your manufacturer so that you are synchronized with them, it is time to start to design your stackup. Here is where having the best PCB design tools that you can get at your disposal will be a huge help. With advanced PCB design tools you can specify the complete layer stackup of your PCB design including the materials and widths of the conductor and dielectric layers. With this information built into the system you will have complete fabrication data that can be used for calculations, simulations, and eventually output documents and drawings for manufacturing.

The PCB design system that we use is OrCAD PCB Designer, and with its cross section editor it can create PCB layer stackups in full detail. OrCAD PCB Designer is a powerful set of design tools giving you the ability to capture and simulate your design in a schematic followed by creating the physical design in layout. Furthermore, if you are using the IPC-2581 format, you can have your stackup imported from your vendors.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.