Altium NEXUS Documentation

Glossary of Design Terms

Created: November 13, 2017 | Updated: August 13, 2019

Technical jargon and terminology is something that typically 'goes with the territory' for most involved in the design of electronic products. But different design tools often adopt a terminology all their own, associated with the features and functionality they deliver.

In some cases, moving from one tool to another would be a breeze, if only the terminology - for similar features - were the same, or at least explained. While the former is not going to happen any time soon, the latter can be handled effectively through use of a Glossary.

This page aims to satisfy this very requirement, and presents the meanings behind various terms that appear while designing with Altium Design solutions, clustered into suitable categories.

By no means exhaustive, this glossary of terms associated to designing with Altium will continue to grow over time, but all the while helping to demystify the unfamiliar jargon you may encounter.

Term Meaning
Blind Via A via that starts on a surface layer, but does not continue all the way through the board. Typically a blind via descends 1 layer, down to the next copper layer.
Buried Via A via that starts on one internal layer and ends on another internal layer, but does not reach a surface copper layer.
Core A rigid laminate (often FR-4) with copper foil on both sides.
Double-Sided Board A board that has 2 copper layers, one on either side of an insulating core. All holes are through holes, that is they pass all the way from one side of the board to the other.
Fine Line Features and Clearances Tracks/clearances down to 100µm (0.1mm or 4mil) are considered standard for PCB fabrication today, the current technology limit available in component packaging is around 10µm.
High Density Interconnect (HDI) High Density Interconnect technology, a PCB that has a higher wiring density per unit area than a conventional PCB. This is achieved using fine line features and clearances, microvias, buried vias, and sequential lamination technologies. This name is also used as an alternative to Sequential layer Build-Up (SBU).
Microvia Defined as a via that has a hole diameter smaller than 6 mils (150µm). Microvias can be photo imaged, mechanically drilled, or laser drilled. Laser drilled microvias are an essential High Density Interconnect (HDI) technology, as they allow vias to be placed within a component pad, and when used as part of a build-up fabrication process, allow signal layer transitions without the need for short tracks (referred to as via stubs), greatly reducing via-induced signal integrity issues.
Multilayer Board

A board that has multiple copper layers, ranging from 4 to over 30. A multilayer board can be fabricated in different ways:

  • As a set of thin, double-sided boards that are stacked (separated by prepreg) and laminated into a single structure under heat and pressure. In this type of multilayer board the holes can be all the way through the board (through-hole), blind, or buried. Note that only specific layers can be mechanically drilled to create the buried vias, as they are simply through holes drilled in the thin double-sided boards before the lamination process.
  • Alternatively, a multilayer board is fabricated as just described, and then additional layers are laminated onto either side. This approach is used when the design demands the use of microvias, embedded components, or rigid-flex technology.
Prepreg A glass-fiber cloth, impregnated with thermosetting epoxy (resin+hardener) which is only partially cured.
Sequential Lamination The name given to the technique of creating a multilayer PCB which includes mechanically drilled buried vias (drilled in the thin, double-sided boards prior to final lamination).
Sequential layer Build-Up (SBU) Starts as a core (double-sided, or an insulator), with conductive and dielectric layers formed one after the other (using multiple pressure passes), on both sides of the board. This technology also allows blind vias to be created during the build-up process, and discrete or formed components to be embedded. Also referred to as High Density Interconnect (HDI) technology.
Surface Laminar Circuit (SLC) Starts as a multilayer core, with build-up layers added on either side (typically 1 to 4). The common notation used to describe the finished board is Build-up copper layers + Core copper layers + Build-up copper layers. For example, 2+4+2 describes a board with a 4 layer core, with 2 layers laminated on either side (also written as 2-4-2). This technology allows blind vias to be created during the build-up process, and discrete or formed components to be embedded.
Term Meaning
Account The account is each organization's record of details in Altium's database. Account details can be accessed by an account administrator through the Altium Dashboard.
Activation This is the process that notifies Altium that the license is now in use. For a time-based license this also commences the time period. An Altium License File (*.alf) is created as part of the activation process, which is then used to enable the Altium software. If activation is being performed for a Standalone or Private Server license, the ALF file is downloaded to the default download location defined for the browser being used for activation. The user must then perform the standard licensing process from within their Altium Design Software to complete the activation process for these 2 license types. Activation of other license types is automatic, no further user intervention is required to complete the activation process.
Activation Code The code issued by Altium that is used to activate the software.
Contact Also referred to as the Notification Contact, this is the user that is nominated to receive (email and mail) notifications from Altium about software, content and services, and other matters related to the provision of Altium’s software, content and services. The contact is defined when the software license is purchased.
Group A collection of users, created by a Group Administrator. Groups are created to help manage license assignments and usage across the company. You would typically group users by company department - for example, a certain design team could be one group. Users are assigned to a group and then that group is assigned licenses, which are only available to members of that group.
Group Administrator Dashboard Account administration tasks can only be performed by a Group Administrator. For each Account a Group Administrator is defined when the Account is first created. A current Group Administrator can also promote another user to also be a Group Administrator.
License The software license is the entity that a customer purchases from Altium. The license gives them the right to use the Altium software specified by that license, under the terms defined in the End User License Agreement (EULA). A license is purchased for a specific number of seats of Altium software, the number of seats (number of PCs that can run the software simultaneously) is shown on the Licenses page of the Dashboard.
License Type

The license Type defines how the License is currently configured to be enabled.

  • On-Demand - In this mode a license is requested when the Altium Design Software is started on a given PC, the license is then held while the software is open, then released when the software is closed on that PC. That license is then available to other installations of the software. To run in this mode the PC must have internet access to one of Altium’s Account Management Servers.
  • Standalone - this license type licenses the Altium software on a specific PC. Continuous connectivity to an Altium Account Management Server is not required for this license type, as the license activation file (*.alf) is retained on the PC.
  • Private Server - client-side license acquisition is administered by the Private License Service of an Altium Infrastructure Server - a free, on-premise server that provides remote Altium product installation and license management. The Infrastructure Server, installed on a PC connected to the company LAN/WAN, is set up by an administrator to acquire the company's Altium licenses and then using its PLS, serve these over the network to Altium software installations. When initially acquired from Altium's web-based license service, the licenses are converted to Private Licenses for localized access. A seat (instance) of a PLS-hosted Altium license can be 'leased' by workstation software when it is in use, and then 'revoked' (returned to the available pool of licenses) when no longer required. Licenses can also be served on a Roaming basis, where the license seat is leased to the target machine for a specified time, allowing the software's host PC, say a laptop, to 'roam' freely while isolated from the network.
Member When a user is added to a group, they are referred to as a member. A user can be a member of more than one group.
Perpetual A software license that has no expiration date.
Seat The individual installation of Altium software running on a PC. The number of seats associated with a software license is determined when the license is purchased. Each seat must have access to a valid license to function correctly, and to be legally licensed for usage.
Serial Number A unique serial number is used to identify each Altium software license.
Subscription Altium Subscription gives the user access to both software releases and updates and new content and services, released during the subscription time period.
Time-based A software license that continues to operate while the user has valid software subscription. When the software subscription expires the software license will cease to operate.
User An individual that is registered in your Altium Account as a user of Altium’s software and AltiumLive content and services. Users can have one or more Altium Software Licenses allocated.

Defines the scope of how a license can legally be used; including:

  • Commercial - the software can be used to generate income in a professional development environment.
  • Commercial Trial - the software can be used to generate income in a professional development environment, but only for the period of time specified as the Trial period.
  • Educational - the software can only be used for educational purposes in an approved education institution, for non-commercial designs.
  • Internal Altium Use - the software can only be used by a current Altium employee, for Altium-related design work.
Term Meaning

The revision in the repository that you checked out to be your local Working Copy. Also called the checked out revision.


To save your working copy of the file into the repository. Referred to as Commit in SVN.


To take a copy of a file from the VCS repository into a working folder. This is generally the latest revision of the file, but all earlier revisions can also be checked out. Depending on the VCS, the file can be flagged as simply checked-out, or checked-out exclusively (locked).


Save the working copy of the file back into the repository. Referred to as Check-in in some version control systems. In Altium Design Software, the normal Save command saves an edited file to the working folder, whereas Commit saves that folder file to the repository as a new revision (version).


The situation when two users attempt to commit changes that affect the same region of the same file. These must be resolved, either using a Merge tool, manually, or by determining which version will dominate (become the new revision).


The master storage of all the files under version (or source) control - also known as the Repository in practice.


The latest revision committed to the version control system.

Log message

A comment about changes made to a revision when it is checked back in (committed) to the repository. The log messages can be used as a summary of the progress of changes in a file.


Many version control systems support the concept of a project. A VCS project is a set of related files which can be checked-in/out as a set. The VCS may also support other project-type features, such as setting a version number on all files in a project. This is distinct from the concept of an Altium Design project, which can be added to Version Control using the Add Project Folder to Version Control command.


The master storage of all the files under version (or source) control - can also be known as the Database.


A committed change in the history of a file or set of files. This is the numerical reference supplied by the VCS to track the different editions (versions) it is holding of the file.


The folder where files are checked out to from the repository, so they can be worked on - also referred to as the Working Folder. Files checked out from Altium Design Software are automatically loaded.


Subversion is an open source version control system. Altium Design Software has a direct SVN interface, allowing revisions to be directly tracked and accessed from its Storage Manager panel. This makes it easy to compare different revisions of schematic and PCB files.


The act of checking for and 'pulling in' changes from the repository version of a file to a working copy (the complement of Commit, or Check-in). The process of merging in any differences requires a Merge tool, or manual updating.


Version Control System: A generic term applied to any tool that is capable of managing file version history and file retrieval.


The term version is normally used to refer to the external reference number allocated by a human to the controlled files, or their output (such as in the case of source code). Most often this is considered as a revision.

Working Copy

The 'local' copy of a file that changes are made to - normally resides in the Working Folder.

Working Folder

The folder where files are checked out to from the repository, so they can be worked on - also referred to as the Sandbox Folder. Files checked out from Altium Design Software are automatically loaded.

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