PCB stack-ups represent the construction of multilayer circuit boards. They provide vital information like material thickness and copper weight required to fabricate a board. Stack-ups also determine the trace width, trace spacing, and reference planes of controlled impedance traces. These layer stacks are sometimes called build-ups. Circuit boards with accurately stacked layers offer improved signal integrity by reducing electromagnetic emissions and crosstalk.
Our Stackup Designer provides precise options for cost-optimized build-up structures. It also includes an impedance calculator to get the desired impedance and trace and space values on any signal layer.
Our tool has the following features that will help you to design a reliable build-up:
In this section, we will describe the steps to design a board stack-up using our tool.
It has 2 sections:
In this section, project name, revision number, PCB size (length and width), target board thickness, material, and board type are keyed in. If you are not sure about choosing the material, click on the material selector compare guide. This will allow you to view the datasheets of various materials and compare their attributes.
After filling in the board info, you can move on to the stack-up design section.
Here, you will have to choose one of the following options:
Choose the first option if you know the number of layers required in your design.
Next, you will have to input the layer count along with the signal-plane layer combination and click on run stack-up generator. For demonstration purposes, we have chosen the layer count as 8 which includes 4 signal and 4 plane layers.
You will be presented with Sierra Circuits’ recommended solutions as shown below.
Each of these options has the following information:
Click on the report to view the stack-up.
Here, you can tweak all the board attributes using the respective dropdowns except the project name and board size. If you make any changes to the board properties, hit generate custom stack-up to view the updates.
Scroll down to view the detailed stack-up.
The detailed build-up comes with the following information:
If your design has controlled impedance traces, you can use our built-in impedance calculator. This calculator allows you to add the impedance model and compute the desired trace geometry and spacing for a target impedance.
To add the impedance models, click on ⊕ under the impedance calculator section and provide the following details:
Please note that you can only choose coated microstrip models if you have solder mask layers in the build-up. The uncoated models can be selected after the removal of solder mask layers. To remove the solder mask from your design, click Ⓧ on the layer number column.
After providing the required impedance data, click on calculate impedance to view the required trace width, calculated impedance, and propagation delay.
If you would like to view other parameters such as trace thickness, inductance, capacitance, and effective dielectric constant, click on 👁 (eye symbol). This will redirect you to our impedance calculator.
Below the built-in impedance calculator, a section named, technology parameters and cost index will be displayed. This section provides the technology levels and via set information. The technology level, for a given layer stack, defines the drill size, pad size, and trace width parameters that can be used.
If you’re not sure about the number of layers required in the design, and there is a complex BGA that dictates the number of layers, choose the option I do not know the number of layers in the design, but I have a complex BGA.
Here, you’ll have to select the applicable BGA pattern and enter the BGA pin and pitch information. Once the required data is given, the Stackup Designer automatically calculates the total number of pins and the estimated number of signal pins. You can change the estimated number of signal pins in this section.
Now, click run stack-up generator present at the bottom of the page. The tool now displays the stack-up options based on the provided input.
The recommended solutions are very similar to the previous option (Choose a Sierra standard stack-up) except for the board thickness.
Choose a suitable option and click on report. This will present a stack-up that works for your BGA.
You can also edit the build-up and the BGA attributes if required. Please remember to hit generate custom stack-up if you make any changes to the provided data.
The layer details and the impedance calculation steps are the same as we saw in the previous option. The only difference is that now the BGA fan-out recommendations are available at the bottom. This provides the following information:
Designing a precise and detailed stack-up at the initial stages of a layout reduces unnecessary board re-spins, optimizes the cost, and increases manufacturability. Our Stackup Designer will assist you to make the right decisions before designing the layout.
Fabrication, Procurement, & Assembly. PCBs fully assembled in as fast as 5 days.
Fabrication. Procurement & Assembly optional. Flexible and transparent for advanced creators.
Complex technology, with a dedicated CAM Engineer. Stack-up assistance included.