# Stackups

### Overview

Stackups describe how layers and materials are arranged on a printed circuit board (PCB). A complete stackup includes the following information:

* Board thickness
* Number of layers\
  Purpose of each layer (signal, ground, power)
* Type of material used in each layer, including key details like dissipation factor (Df) and dielectric constant (Dk)
* Thickness of each layer and copper layer
* and more!

All ECAD tools supported by Quilter let you specify these details as part of your board's stackup. 

### How Quilter uses stackups

Physics constraints that depend on stackup details – like differential pairs and high current nets – are always tailored to the stackup details Quilter is compiling for. 

Quilter can read and write stackup information to the native CAD files you upload and download from our platform. Quilter always writes information about the stack-up it used to the downloaded board file to support a thorough design review.

### Stackup from your input files

The stackup and design minimums from your files will be an option at the top of the Stackups step, if they have been configured and detected correctly. 

<figure><img src="https://1761213452-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FL9R6Vsa5jGn27oTws0tG%2Fuploads%2FULLah2rt6Hf2ErIV3mlP%2Fimage.png?alt=media&#x26;token=173a8f9f-ee07-436f-8d0f-7a132cba4ac8" alt=""><figcaption></figcaption></figure>

{% hint style="warning" %}
**Make sure to name ground layers "ground" or "gnd" and power layers "power" or "pwr" so that Quilter will respect that intent when compiling your board.**
{% endhint %}

### Predefined Quilter stackups <a href="#h_4d3a642408" id="h_4d3a642408"></a>

For each layout candidate Quilter generates, it uses a specific stackup and associated material properties. These are used to test routing strategies and complete the necessary physics calculations for implementing signals that are sensitive to physics, such as [differential pairs](https://docs.quilter.ai/physics-constraints/differential-pairs).

We've predefined standard stackups with our preferred fabrication partners, including JLCPCB, MacroFab, and CircuitHub.

<figure><img src="https://1761213452-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FL9R6Vsa5jGn27oTws0tG%2Fuploads%2FlBbTCUZWu1Wslpiiajri%2Fimage.png?alt=media&#x26;token=bf14a032-127c-4547-bc98-b227fa61a7e1" alt=""><figcaption></figcaption></figure>


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