Wire Bonding Copper Ball Heating Device And Experimental Research

Now the application of electronic packaging technology, more than90%of the integrated circuit encapsulation is the wire bonding technology, and now lead bonding mainly adopts pure gold wire, the production cost is quite high. With the development of electronic packaging technology, packaging pin number increasing, lead spacing smaller, encapsulated in the substrate of the area will be smaller. Many scholars found that gold was more and more unsuitable for multi pins of the IC encapsulation. In recent years, the copper wire bonding technology began to be used in integrated circuit encapsulation,in many schools, scientific research institutions at home and abroad, the enterprise engaged in the research, copper wire have good conductive thermal conductivity, good mechanical properties, excellent properties such as low dielectric constant, in line with the development trend of multi-pin chip bonding.The copper wire bonding two main problems:the first, chemical stability of the copper surface is easy to be oxidized to form an oxide film, caused by the welding strength is low, a lesser weld phenomenon; The second is high hardness of copper bonding high pressure and ultrasonic power, so that it will cause a splash plot of the aluminum layer of the substrate, chip partial rupture and crater failure phenomenon. Aiming at the problem of easy oxidation of copper wire, the general use of laziness protective gas, now commonly used is95%N2/5%H2gas mixture, the mixed gas can effectively protect the less copper oxide. As for the problem of high hardness, the domestic and foreign researchers found a number of new processes and methods, such as recrystallization annealing treatment, double firing the ball, the burning ball current and short period of time, the hardness of the copper ball can be decreased.This article focuses on the hardness of the copper initiate the relevant study, proposed method using resistive heating to soften the ball, in order to reduce the hardness of copper balls in the bonding process, to avoid cracks and craters phenomenon. The main method used is to design improvements on the basis of the gold wire bonder and design a corresponding metal capillary, gold wire bonder and the coordination of the resistance bonding power supply, In the trigger of ultrasonic vibration and resistance welding power source discharge, Through the capillary tip and the copper ball contact resistance discharge heating copper ball.Using ABAQUS finite element simulation, the main consideration have pressure、 ultrasonic power on the bonding process, using the results of the finite element simulation to guide the experiment, the optimum experimental parameters, reduce the number of experiments.In the experimental study, the main parameters of pressure and ultrasonic power by single factor experiment compare gold and copper wire bonding performance.