The study of the epoxy-based anisotropic conductive adhesive in electronic packaging interconnects applications (chip-on-glass, chip-on-flex, etc. especially in RFID applications) has received particular attention. This is due to its potential advantages of finer pitch printing, reducing environmental contamination. The thermal curing process is critical to develop the ultimate electrical and mechanical properties of the ACA devices. In this article, the curing kinetics of ACA was studied with a differential scanning calorimeter (DSC) under constant heating rates conditions in the range of 520 °C/min. The model free method was used to describe the curing reaction. The degree-of-cure and the activation energy through the whole conversion range were mathematically determined and used to predict the progress of the curing process. Experimental results show that the activation energy of the ACA varies significantly with degree-of-cure during the curing process. The peculiar phenomenon indicates that the ACA underwent a complex series of reactions. The kinetics of curing reaction changes when large conversion values are reached at low heating rates. The change in the reaction kinetics is due to vitrification of the ACA during heating. In addition, the degree-of-cure of the ACA as a function of bonding times during isothermal ACA bonding process was theoretically predicted.
It is difficult to keep the precise conveyance in film discontinuous winding system, while there are no etch or print marks on the transparent film. Based on dark field illumination theory, a micro-indentation detection method is proposed for multilayer structured transparent film roll-to-roll processing. Two parallel strip lights are involved in the vision system to illuminate the indentation at a low angle, which ensures that the distinct image of the cutting indentation can be obtained in reflection and diffuse homogeneous lights. The measurement of micro-indentations can be used to evaluate the film conveying positioning accuracy and calculate the compensation of film feeding position control. An experiment platform was established to show the efficiency and feasibility of proposed scheme. Experimental results showed that the micro-indentation detection method, based on dark field illumination, is successful to increase the feeding precision of multilayer structured transparent film discontinuous winding system.
Due to the nonlinearity, time-varying and load disturbance in linear servo system, the conventional PID control is hard to get an ideal control effect, this paper deduces the mathematical model of the permanent magnet linear synchronous motor (PMLSM) direct drive system, designs a fuzzy PID controller by combining fuzzy control with conventional PID control, adjust the parameters of PID controller in real time by making use of fuzzy control's ability of adjusting online. Simulation and experimental results show that the fuzzy PID controller is superior to the conventional PID controller in responsiveness, steady performance and dynamic tracking, which can shorten the positioning time, improve the system positioning accuracy.
For the pick-and-place operations of GDL, this paper presents and obtains the control system model using system identification method, and analyzes three distinct stages for the motion characteristics in pick-and-place operations. To satisfy the stick requirements for contact force control, a force controller based on fuzzy adaptive PID algorithm and a position controller based on feed-forward control are presented and designed. Simulations are carried out to verify the feasibility and effectiveness of the proposed control method. The above control strategies and methods are applied to pick up and place GDL. They can also be extended to the pick-and-place operations of the chips and other filed, which has broad application prospects.
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