Fast Feedrate Scheduling and PVT-based High Precision Interpolation for Wire Bonding Operation

Abstract

With the rapid development of electronic packaging technology and the improvement of electronic integration, chip packaging technology with fine pitch, high density and reliability are highly demanded. For electronic packaging technology, the high-speed wire bonding equipment plays an important role for the high efficiency operation and high quality production. For wire bonding equipment, one of the key issues is to ensure a high-precision tracking trajectory for the wire looping process under high-speed motion. Hence, this paper proposes a novel NURBS interpolator that combines optimal feedrate scheduling and PVT interpolation algorithm to improve the wire looping quality. Firstly, under the consideration of various contour accuracy constraints, a feedrate scheduling model is established based on the fitted NURBS path, and a time-optimized feedrate profile is quickly planned by simplifying the model. In order to improve the interpolation accuracy and simplify the internal operation process of the interpolation, the interpolator is developed by adopting the idea of piecewise fitting, adding derivative constraints at the piecewise points, and using the Lagrange multiplier method to obtain a curve that satisfies the fitting precision. The motion trajectory of each axis is converted into a time-synchronized continuous cubic curve, and then these cubic curves are converted into PVT (position-velocity-time) interpolation instructions according to the principle of Hermitian interpolation. The method in this paper belongs to the curve interpolation method. Even at the corner of the path, the calculated interpolation point can accurately fall on the target path. At the same time, the proposed method can achieve higher contour accuracy with fewer interpolation commands.