Transient Flexure
Mechanical deformation of a printed circuit board under transient loads represents a critical quality concern during automated assembly. Process engineers measure dynamic deflection to quantify how much a circuit card bends when subjected to localized forces from pick-and-place nozzles or test probes. If the board bends beyond acceptable thresholds during these operations, delicate solder joints or multi-layer ceramic capacitors can fracture.
This measurement tracks the movement of the substrate in real time rather than observing only the final resting state of the assembly.
Thermal Stress
In thermal environments like reflow ovens, differential expansion between resin and reinforcement generates substantial mechanical force. Here, dynamic deflection occurs as the board passes through different heating zones, with the substrate twisting or bowing as temperatures rise. Unsupported spans of thin laminates are especially vulnerable to this type of distortion.
High temperature co-fired ceramics and glass-epoxy composites exhibit different degrees of displacement under these thermal profiles, which can lead to misaligned components or bridged solder connections when the board cools. Support pins and custom pallets minimize this movement during the oven transition.
Inspection Method
Metrology systems utilize laser triangulation sensors to capture the change in board height during active processing. This test detects surface height deviations of less than ten micrometres. Placing sensors at the points of highest stress allows manufacturers to adjust tooling support before defects occur.
