The effect of interface reaction with different finishes and SnAgCu on the reliability of solder joints

BGA device is always inefficient for its solder joints, of which part the interface intermetallic compounds (IMC) is most likely to crack. What´s more, interfacial reactions are becoming more complex these days as the lead-free alternative becoming an urgent requirement for electronic industry and various materials being applied in electronics packaging application. Taking account of the above reasons, it´s of great significance to take out a research on the influence of IMC on the reliability of the BGA product. This thesis mainly concerns on different kinds of IMC formed under different PCB plating layer and the effects of those IMCs on the reliability of the solder joints. Large amount of statistics show that most of the electronic components lost their efficacy under the instantaneous momentum and the thermal stress. Hence this thesis has investigated the reliability of interconnections between SBGA and PCB with different plating layer under drop test and temperature cycling test. After each stage of the test, add up the number of cracking solder joints by X-ray. Then, the components were made of metallographic samples, and the phases of different IMCs were identified by Energy Dispersive X-ray (EDX) and Scanning Electron Microscope (SEM). Some were tested using the red dye penetration method. By analyzing the experiment and simulation, it is found that: (1) The solder paste reliability of the SBGA components reflowed on the OSP and EING finish boards were significantly better than that of the components soldered on HASL and Immersion Ag boards for drop test. SBGA components failed sooner for the boards with Immersion Ag pad finishes. The initial reliability of the SnAgCu solder on ENIG finish boards is greater than that of the SnPb solder shifting the failures to the PCB, and the SnPb solder on OSP, HASL and Immersion Ag is better than that of the SnAgCu solder. (2) The solder joints have the best strength when using the ENIG finishes and comparatively less w- - hen using the OSP finishes for temperature cycling. What´s more, when using the HASL finishes, the solderability is the best and the Immersion Ag finishes is the worst. The overall strength of the SnAgCu solder is greater than that of the SnPb solder after the temperature cycling.