Pick and Place Machine Vision Calibration for Fine Pitch Components
Fine pitch machine vision calibration requires quartz grid targets, telecentric optics, and closed-loop thermal drift compensation to hold 5 µm accuracy.
Optical Resolution
Resolving Power
Ability of an imaging system to distinguish two closely spaced objects as separate entities defines the limit of its inspection capability. High optical resolution is necessary for identifying fine-pitch components and verifying the integrity of microvias on dense circuit boards. Resolution depends on the wavelength of light used and the numerical aperture of the lens.
Diffraction Limit
Diffraction effects at the edges of the lens aperture set the theoretical maximum for what the system can see. When discussing optical resolution, engineers refer to the airy disk pattern created by a point source of light. As the features on a board become smaller than this pattern, the image blurs and the system can no longer detect defects.
Feature Detection
Hardware choices like sensor pixel size and lens quality determine the practical performance of the vision system. A system with poor optical resolution cannot be salvaged by high-resolution sensors because the lens itself fails to deliver sharp data. Improving the light intensity or moving to a shorter wavelength like blue light can enhance the clarity of the captured image.
The contrast ratio between the traces and the board substrate also impacts the ability of the software to resolve edges accurately.