Measuring PCB dimensions can be done using either digital tools within design software or physical tools on a manufactured board.
Accurately measuring the dimensions of a Printed Circuit Board (PCB) is crucial for design verification, manufacturing, assembly, and ensuring the board fits correctly into its intended enclosure. There are two primary methods: digitally within PCB design software and physically on a finished board.
Digital Measurement in PCB Design Software
Modern PCB design software includes powerful tools specifically for measuring distances and verifying dimensions directly within the design files.
- Using Measurement Tools: Software like Altium Designer, Eagle, KiCad, and others offer dedicated measurement commands.
- Typically, you activate a command (e.g., "Measure Distance," "Interactive Measurement").
- As noted in descriptions for tools like Altium Designer, once the command is active, the mouse cursor takes the form of crosshairs.
- You then specify two points on the design canvas by clicking. The software instantly calculates and displays the distance between these two points, often in multiple units (mils, inches, millimeters).
- What to Measure Digitally:
- Overall board length and width.
- Distance between mounting holes.
- Spacing between component pads (e.g., for verifying connector footprints).
- Distance between trace segments or features for design rule checking.
- Coordinates of specific points or components.
Digital measurement is essential during the design phase to ensure layouts meet specifications and design rules before manufacturing.
Physical Measurement of Manufactured PCBs
Once a PCB has been manufactured, physical tools are used to verify the dimensions against the design files or specifications.
- Tools Used:
- Rulers: Simple and effective for basic overall measurements.
- Calipers: More precise tools (digital or manual) ideal for measuring external dimensions, distances between hole centers, component sizes, and board thickness.
- Optical Comparators or Vision Systems: For highly precise measurements and verification of small features.
- What to Measure Physically:
- Overall board length and width.
- Location and diameter of mounting holes.
- Positions of connectors and large components.
- Board thickness (important for connectors and enclosures).
- Spacing between critical features.
Physical measurement is vital for quality control and ensuring manufactured boards match the design intent and any required tolerances.
Digital vs. Physical Measurement
Here's a quick comparison of the two methods:
| Feature | Digital Measurement (Software) | Physical Measurement (Manufactured Board) |
|---|---|---|
| Phase | Design and Verification | Quality Control and Verification |
| Tools | PCB Design Software Measurement Commands | Rulers, Calipers, Optical Comparators |
| Precision | Limited by software resolution and design | Limited by tool precision and user skill |
| Speed | Very fast for specific points | Depends on tool and complexity |
| Purpose | Design validation, DRC, layout checks | Manufacturing QC, fit checks |
Both methods are important in the PCB lifecycle. Digital tools allow for precise design and verification before manufacturing, while physical tools confirm that the manufactured product meets those specifications.
