Research On Techniques Of Ultrasonic Monitoring On Gold Wire Bonding

Gold wire bonding is the key to the packaging procedure and sensitive to ultrasoundwhich has much impression on the forming of bonding strength.Realizing the ultrasoundon-line monitoring of bonding quality has important significance to improve the reliability ofwire bonding.Setting up the relationship between electrical signal and the strength of wirebonding through the monitor and analysis of ultrasonic electrical signal is put forward formonitoring the quality of wire bonding. The major work is as the following aspects:(1) In view of the work situation of gold wire bonding system,the design of ultrasoundon-line monitoring system is given.It contains the circuit design of real-time signalsensing,acquisition processing and communication module etc.(2) The median filter is used to preprocess ultrasonic electrical signal.The capturedelectrical signal are filtered by digital bandpass filter banks to obtain the correspondingsubband signals such as fundamental signal,second harmonic and third harmonic.Eachsubband envelope is obtained using the Hilbert transform for further feature extraction.Therelations between bond quality and ultrasonic electrical signal were analyzed briefly.(3) Aimed at the condition of different bonding,nine features were selected,such as therise time and slope of baseband signal of bond process,root mean square values of basebandsignal etc.Using the selected features as inputs and bonding strength as output,the bondingquality model of ultrasound on-line monitoring based on Neural Network is established.Therelations between ultrasonic electrical signal and bonding strength is acquired by a BPNNtraining.The above methods were applied in the aluminum wire bonder U3000.Therecognition of bond failure and estimate of bonding strength were realized.