Understanding Rules And Constraints

David Haboud
|  Created: September 27, 2018  |  Updated: March 16, 2020

This webinar will discuss how Altium Designer supports your design process with hierarchical rules and constraints. Knowing how to define design guidelines enables you to create first pass designs without having to memorize every requirement.

Why use Rules and Constraints?

Every logical schematic design defines requirements for your physical PCB. Satisfying these requirements requires understanding and consistency throughout the entire design process. How do you validate every requirement while maintaining accuracy?

There are many challenges to requirement adherence, but we will focus on three challenges and how we will be able to overcome them with Altium Designer.


1. Requirement Interactions


Schematic/Logical Requirements

PCB/Physical Requirements





Rule Hierarchy

Conflicting Scope

2. Error Resolution


Seeing Errors Early


Associated Design Aspects


Fixing Errors While Avoiding New Ones


3. Validation and Proof


Requirement Compliance


Requirement Visibility





Overview of Rules and Constraints Key Benefits and Capabilities


  1. Define scope, category, and prioritization of design constraints
  2. Validate and report logical and physical design requirements
  3. Automate and resolve DFM and electrical checks

Electrical and Design Rules

Define logical and physical requirements.

Enables rule, constraint, and check hierarchy.

5 Steps to Rule Creation:

1.Create New Rule

2.Name Rule

3.Define Scope

4.Set Value

5.Adjust Priority


Rules and Constraint Hierarchy

Visualize Scope and Priority

Organize requirements

Add/remove items quickly

Traceability and reproducibility

Save/share hierarchy


Rule Wizard

Quick, guided rule and constraint creation

Rule type visibility


Real-time Design Guidance

Automation to ensure requirement adherence

Stops you from making mistakes

Eliminates need to remember all requirements manually


Design Rule Check Options (DRC)

Configure rule checks

Online – real-time as you design

Streamline usage

Batch – executed on DRC

Utilize “Used On”


PCB Rules and Violation Panel

Traceability and navigation of existing issues

Violation visibility

Run individual and batch DRC

Waive unavoidable violations

For example, an edge connector failing to meet board outline clearance

Validation Reports

Proof of logical and physical requirement adherence for formal release

Traceability of existing issues

Violation recording

Easily shareable


Questions and Answers

Below are the top asked questions for the webinar. Questions focusing on specific support questions and feature requests are omitted.

Q: Can we create rule templates?
A: You can import and export RUL files and share them with your team to ensure everyone is using the same rules and constraints. You can save them with Altium Vault and Altium NEXUS Server to ensure your rules are in a centralized location for everyone.

Q: What are the filters other than 'room' that can be used for localized rules?
A: You can define the scope of rules with pad name, net, classes, and just about any design aspect.

Q: Where can we get access to the Query functions?
A: You can find the Query Language Reference on our documentation page following the link: https://www.altium.com/documentation/18.1/display/ADES/((Query+Language+Reference))_AD


Q: Did you have to do anything to get the trace to neck down when it entered the room?
A: The rule hierarchy and scope I created in the webinar allow automatic neck-down of the trace as it enters the room with the custom query: TouchesRoom(‘BGA_Area’).



We discussed the requirement adherence challenges and how rules and constraints help resolve those challenges. You can review below the functionality in Altium Designer and the challenges they address in turn. Properly using rules and constraints allows you to meet and validate all requirements easily without having to manually keep track of everything necessary for a successful design. You are able to prevent, navigate, and correct errors in real-time and benefit from design automation to give you a helping hand.

Requirement Interactions

Define scope, category, and prioritization of design constraints.

Electrical and Design Rules

Rules and Constraint Hierarchy

Rule Wizard


Error Resolution

Automate and resolve DFM and electrical checks.

Real-time Design Guidance

Design Rule Check Options (DRC)


Validation and Proof

Validate and report logical and physical design requirements.

PCB Rules and Violations Panel

Validation Reports

About Author

About Author

David Haboud is a Product Marketing Engineer at Altium. He studied electrical engineering with an emphasis in computer architecture and hardware/software design at the University of Southern California. David began his career as an embedded software engineer in the aerospace industry and has always strived to make it easier for hardware and software engineers to communicate. During his tenure as an embedded software engineer, he focused on firmware development and data acquisition for auxiliary power units. In his spare time, David hosts and performs in improvisational and stand-up comedy nights in San Diego, California.

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