In Circuit Fixture Spring Probe Force Balancing on Ultra Fine Pitch Assemblies
Balancing micro-probe forces with precision push-fingers prevents substrate strain over 500 microstrain, protecting fine-pitch BGAs and MLCCs from fixture damage.
Plunge Travel
Stroke Measurement
Mechanical stroke distance defines the vertical range of motion for a component placement head or a test probe during operation. Plunge travel must be sufficient to reach the surface of the board without bottoming out the internal spring mechanism of the tool. Precise calibration of this distance prevents damage to sensitive components and ensures reliable electrical contact.
Tooling Depth
Coordinate programming involves the vertical settings used by the assembly machine to execute a placement. The machine calculates the necessary plunge travel by measuring the height of the component and the thickness of the substrate. If the travel is too short, the component will not reach the solder paste, resulting in an open circuit.
Excessive travel can crack ceramic packages or deform the board surface. Modern systems use laser sensors to verify these heights in real time before every stroke.
Force Control
Pressure regulation manages the force applied at the bottom of the stroke to protect the assembly. When plunge travel is correctly managed, the downward force remains within the limits of the component specification. High-precision actuators allow for a soft landing that preserves the integrity of both the part and the pad.
This parameter is a primary setting in the setup of automated placement equipment.