# Pre-placed components

### Overview

Quilter treats all components within the board boundary at upload as "pre-placed." 

**As a core principal rule, Quilter doesn't change the position or orientation of pre-placed components.** 

When compiling, Quilter will place and route components that were left outside the board outline.

{% hint style="success" %}
**Overhanging Components**\
Quilter can handle pre-placed components with overhanging design elements or component outlines, such as an ESP32 module with a PCB trace antenna positioned off the edge of the circuit board.
{% endhint %}

### Why should I pre-place components?

There are a few reasons to pre-place components:

1. **Location-sensitive components**\
   One main reason to pre-place a component is to make sure that location-sensitive parts, such as mechanical pieces and connectors, end up in the right spot. <br>
2. **Unsupported physics constraints**\
   If Quilter doesn't currently support a physics constraint that demands precise or highly organized placement of components, you can manually position individual components or groups to ensure they're placed correctly. <br>
3. **"Saving your progress"**\
   When working with Quilter, you might find that you like certain elements of a layout candidate, but not the overall design. Once you've downloaded a candidate, you can choose to keep the routing and placements you like, remove the rest, and resubmit to Quilter to save your progress towards a fabrication-ready design.

### How to specify

#### As a preference

Components inside the board outline are locked and can't be moved or rotated by Quilter during compilation. We won't change pre-placed components, even if they stop Quilter from finishing a layout job successfully.&#x20;

If you wish to constrain component placement to pre-specified sides or areas within your board outline, see [placement-regions](https://docs.quilter.ai/design-parameters/placement-regions "mention").

#### As a requirement

Locking the position and rotation of a component is easy: just pre-place it within the board outline and upload your input file to Quilter.


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