It can be argued that selecting the components that will comprise your board is the most important PCB design task. After all, without the right components, your circuitry will not function as desired. Your board’s operation also depends upon the interconnectivity between components, through-hole or surface mount technology (SMT), by way of traces and vias. Although on-board operation is required, no PCB is deployed in a vacuum and connection to external devices will also be necessary.
Typically, electrically interfacing with nearby external devices is done by common connectors. However, this means that edge clearance depends upon signal type. In some cases, it is preferable to have physical contact between the boards as opposed to a wiring or cable connection such that signals are received simultaneously among multiple devices. For these situations, one board plugs directly into another. A popular way of achieving this direct connectivity is using gold fingers. Irrespective of the connection method, clearance with the board edge is an important issue that impacts the building of your PCB. Understanding the significance of PCB component to edge clearance will enable us to make design decisions to help facilitate board fabrication and assembly.
What is PCB Component to Edge Clearance?
When considering PCB components, some of the following most likely come to mind:
- Passive components - resistors, capacitors, inductors, transformers, diodes, etc.
- Active components - bipolar junction transistors (BJTs), junction field-effect transistors (JFETs), metal-oxide field-effect transistors (MOSFETs), optocouplers, etc.
- Integrated Circuits (ICs) - may contain a single element type, multiple circuits or complete systems.
- Power supplies - batteries, etc.
- Electro-mechanical components - piezoelectric devices, switches, etc.
Listing all of the components that fall into one of the above major categories would be quite exhaustive. Also, the list would be incomplete unless we included connectors like wiring, cable, headers, USB, Ethernet, and gold fingers. When considering the PCB component to edge clearance, connectors must be included as they are the most likely components to be placed near the edge of the PCB.
Why is PCB Component to Edge Clearance Important?
The fabrication and assembly of your boards are conducted in sheets or standard panel sizes. The design of the arrangement of your boards on the panel must be done for manufacturing. You may leave this panelization task to your CM or incorporate it into your design stage. By performing panelization during design, you are able to determine the number of boards per sheet, which impacts waste and manufacturing costs, and control board orientation that affects the depanelization method(s) listed below used to separate the boards back into single units.
Done in a straight line. Requires that adequate spacing between components and the edge be available to prevent damage to components during separation.
More flexible than scoring. A router bit is used to trace around odd shapes. Results in breakaway tabs and irregular board edge when separated.
Creating the best PCB layout design requires you to tailor your specifications to your contract manufacturer’s (CM’s) capabilities. This includes designing for PCB component to edge clearance that complies with the available depanelization techniques of your board manufacturer. As a PCB development team committed to a smooth and efficient process, a high-quality and reliable product should be easily obtainable.
|Tempo‘s Custom PCB Manufacturing Service|
At Tempo Automation, we help you get started on the best path by furnishing information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium user, you can simply add these files to your PCB design software.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on PCB component to edge clearance or how it impacts your board’s design and manufacture, contact us.