Study On Ultrafine Wire Bonding Technology And Performance Of Radio Frequency Devices

As the performance and morphology of Active Phased Array Radars develop to a higher level,more stringent requirements are placed on the volume and weight of T/R(Transmitter and Receiver)components.Wire bonding is one of the widely used interconnection technologies for T/R components,so the size of bonding wires is bound to become smaller and smaller.But ultra-fine wires will cause problems such as low bonding mechanical properties and poor RF performance.Therefore,there is an urgent need to study the process and RF performance of ultra-fine wire bonding in RF devices.This article uses thermosonic wedge bonding to bond ultra-fine gold wires and gold pads in RF devices,explores the bonding process,and simulates the RF performance and matching circuit.As to thermosonic wedge bonding gold wire with a diameter of 10?m and gold tape with a cross-sectional size of 25×5?m to gold pad process,gold wire morphology and tensile force after bonding are first investigated.Then analyzed the broken position of the gold wire after the tensile test.The three-factor four-level orthogonal experiment was used to obtain the best process parameters of these two ultra-fine gold wires.The ANSYS HFSS simulation software was used to analyze the radio frequency performance of the ultra-fine gold wire bonding RF circuit,and investigate the influence of different bonding structure parameters on insertion loss and return loss.The ANSYS Q3 D and ADS software were used to analyze L-shaped network,microstrip single-branch stub and microstrip double-branch stub impedance matching of two types of ultra-fine gold wires.The results show that with the increase of bonding pressure,bonding time and ultrasonic power,the wire deformation rate gradually increases after bonding,and the tensile force of the gold wire increases first and then decreases after bonding.The influence of process parameters on the deformation of the gold ribbon is smaller than that of the round gold wire.Aiming at the problem that the bonding device exerts too much force on the second bonding point,which leads to a large wire deformation and a small tensile force,a method to change the number of bonding points is proposed.Among them,the structural mechanics of three bonding points with the same bonding parameters has the best performance.Three-factor four-level orthogonal experiments show that the best process parameters for bonding 10?m diameter gold wire are 4g pressure,90 LSB ultrasonic power,100 ms time,and for bonding cross-sectional size of 25×5?m gold ribbon bonding are pressure 8g,ultrasonic power 120 LSB,time 80 ms.According to the HFSS simulation results,as the wire diameter increases,the return loss and insertion loss tend to decrease;Within a certain range of arch height,the return loss decreases with the decrease of the arch height;As the span decreases,the return loss and the insertion loss shows a decreasing trend;The return loss of two and three gold wires bonding circuits is almost equal,which is less than that of a gold wire bonding circuit,and the return loss decreases with the increase of the number of gold bonding wire;As the width of gold tape increases,the return loss and insertion loss decrease;At 0-10 GHz,the return loss of gold tapes with different thicknesses is not obvious,but the insertion loss is not much different.At 10-20 GHz,the return loss and insertion loss decreases with increasing thickness of gold tape;At 10-20 GHz,when the cross-sectional area of the gold wire is the same,the RF performance of the gold tape is better than that of the round gold wire,and the aspect ratio of the gold tape has no obvious relationship with the RF performance.According to the ADS matching simulation results,inserting a matching structure can significantly improve the RF performance of the circuit.There is almost no loss of signal in the matching structure circuit of the selected two sizes of fine gold wires inserted into the Lshaped network and the type two microstrip double-branch stub.Different matching structures have different trends of transmission performance with frequency.