Microstrip Isolator Welding Failure Mechanism Analysis And Simulation

In this paper,analysis the failure cause of microstrip ferrite microwave devices for welding thin film microstrip circuit substrate with the metal chassis welding .at the same time,this paper analysis the welding circuit microstrip microwave ferrite substrate film rupture, film microstrip circuit electrical performance of the film off and the product failed.1. There are some reasons for breakdown of the welded film microstrip circuits microwave ferrite substrate:1)Microwave Ferrite substrate have some quality problems in itself.2)Microwave ferrite microstrip circuit substrate in the processing, production process or the welding process, there will be various types of stress exist, when they release the stress in the welding process, or subjected to thermal shock, random vibration and other environmental tests released More than microwave ferrite microstrip circuit capacity of the substrate, the microwave ferrite microstrip circuit substrate will rupture.These stresses including:Ueing Dicing machine to cut the microstrip circuit substrate by a large number of small cuts to the process of the substrate, leading to the edge of the microstrip circuit substrate has stress.Microstrip circuit substrate for the removal of the side of the microstrip transmission line circuit, or adjust the microstrip transmission line circuit in the direction of the substrate size to meet the size of the metal chassis to the corresponding position of the grinding, all those reasons make the microwave ferrite substrate microstrip circuit edge of the existence of stress.In the welding process, the solder paste in the solder flux residue, the formation of hollow, empty and microstrip circuit welding and metal bottom substrate due to thermal expansion coefficient between the different formation of stress. 3)The surface of the metal base plate welding large surface roughness, resulting in the welding process in the microwave ferrite microstrip circuit substrate fracture.2. There are some reasons for microwave ferrite substrate after welding thin film microstrip circuits off.when the film and substrate interface chemical bond between the force is low, the interface between film and substrate binding force mainly depends on the physical and mechanical bonding to combination. In the high-temperature welding process, the interface between film and substrate binding and mechanical combination of physical force a dramatic change, binding decreased to less than the tension of the film, the film microstrip circuits will be off.3. Microstrip circuit substrate and the metal base plate formed in the welding process between the holes, due to the impact of the size and position,resulting in the microwave microstrip circuit substrate ground is not good, causing abnormal electrical properties of the device.According to Failure of welding, the use of the following measures to avoid those failures occurred:1. The metal chassis and microstrip should choose the linear expansion coefficient close to the material processing, and the bottom surface of the metal should be controlled roughness.2. In the welding process control of rising, cooling rate, to reduce the welding residual stress, or eutectic soldering process using alternative heating units welding process, in order to minimize the size and number of welded hollow.3. Using the sputtering measure and a polished substrate can make face-centered cubic structure of the TaN thin film to reduce internal stress using the methods of in the film and substrate interface chemical bonding between the atoms on both sides can ensure that films and ferrite-based microstrip circuit film adhesion; using the surface of the substrate before plating two scrubbing process methods and enhancing the impact of the current method of plating will enhance copper plating layer and rendering the binding force between layers.