Curved Traces

Curved Traces lets you switch from rigid 90-degree routing to smooth, arcing trace segments.

Overview

With Curved Traces, you can define how sharp or smooth your trace corners should be—globally across the board, per net, or down to individual segments. It’s driven by rules like trace shape and trace corner radius, giving you precise control over trace curvature. This makes it easier to design flexible PCBs or improve signal integrity in high-speed traces.

The system is rule-based. After you set the rules, Flux applies them automatically. You choose whether corners should be straight or curved, and you define how round they should be.

Getting Started

Ask Flux to set the curved trace rules at the level that you need.

You can also do it in the editor.

Curved Traces are controlled using layout rules. You can apply these rules at different levels. Here's how to get started:

1- Layout-wide

Ask Flux to set the default trace style of the board.

Best for flex boards or any project where you want all traces to curve by default.

1. Set the default trace style on the board

   1. Navigate to the "Objects" menu and select the Layout element.

   2. Add a Trace Shape rule.

   3. Set it to curved to apply a curved style to all trace segments across the board.

2. Define the corner radius

   1. Add a Trace corner radius rule.

   2. This value defines the minimum radius for any curve (default is ~500µm).

   3. You can increase or decrease it depending on your board’s needs.

2- Net-specific

Ask Flux to set the trace style of a net.

Great if only certain signals are in a flexible area or need rounded routing.

• Set the default trace style for the net

  1. Navigate to the "Objects" menu and select the net you want to modify.

  2. Add a Trace Shape rule.

  3. Set it to curved to apply a curved style to all trace segments that belong to that net.

• Define the corner radius

  1. Add a Trace corner radius rule.

  2. This value defines the minimum radius for any curve (default is ~500µm).

  3. You can increase or decrease it depending on your board’s needs.

3- Segment-specific (fine-tuning)

Ask Flux to set the trace style of one segment.

Only use this when you need to override the behavior for a single segment.

Making both corners of a segment curved

Ask Flux to make both corners of a segment curved.

You can also do it in the editor.

• Select the target segment

  1. Navigate to the "Objects" menu and select the target segment

  2. Add a Trace Shape rule.

  3. Set it to curved to apply a curved style to both corners.

• Define the corner radius

  1. Add a Trace corner radius rule.

  2. This value defines the minimum radius for any curve (default is ~500µm).

  3. You can increase or decrease it depending on your board’s needs.

• Use trace-shape, trace-shape-start, or trace-shape-end on specific trace segments

• curved always overrides straight if both are applied

Making a single corner of a segment curved

Ask Flux to make one corner of a segment curved.

You can also do it in the editor.

1. Select the target segment

   1. Navigate to the "Objects" menu and select the target segment.

   2. Add Trace Shape Start and Trace Shape End rules. Trace Shape Start and Trace Shape End set the corner shape at the beginning or end of a trace segment.

   3. Set the rule for the target corner to curved.

2. Define the corner radius

   1. Add a Trace corner radius rule.

   2. This value defines the minimum radius for any curve (default is ~500µm).

   3. You can increase or decrease it depending on your board’s needs.

Understanding Priorities

• Curved traces take priority: If one segment is curved and the other is straight, the resulting corner will be curved.

• Radius Rules Conflict: If two connected segments have different trace-corner-radius values, one will take priority—usually the one with start defined.

Tips & Tricks

• To create a smooth 90° curve, make sure your segments intersect at a right angle.

• Use the visual inspector or hover over segments to debug which shape or radius rules are active.

• Curves are clamped by trace length. A tight corner won’t allow a large radius, no matter what rule you set.