Research On The Soldering Process Technology Of μBGA Packaged Device

The development of modern electronic information technology is changing with each passing day,the miniaturization,high speed and high reliability of electronic systems require electronic components to change to miniaturization and integration,and at the same time promote the emergence and development of new packaging technology,and the importance of packaging structure represented by ball grid array packaging BGA(Ball Grid Array)in electronic systems is becoming increasingly prominent.Miniaturization has become one of the necessary technical means for electronic products to achieve high integration,high performance,miniaturization,low power consumption and high reliability.At present,designers in existing models have selected Micro BGA(also known as μBGA)devices in miniature ball grid array packages with a solder ball diameter of 200μm.Due to the solder ball diameter of μBGA packaging device 200μm and the center distance of 400μm,its special structural characteristics lead to the traditional Denso process parameters and methods can no longer guarantee the reliability of its welding quality,therefore,in order to master the welding process technology of μBGA packaging device,it is necessary to carry out reliability research to ensure the rationality of its process parameters.This project involves two μBGA packaged devices with a diameter of 200μm and 300μm solder balls,and carries out mounting and reliability verification work,both of which are lead-free solder balls.μBGA’s veneer assembly adopts standard surface mount equipment and process flow,goes through printed board cleaning,solder paste leakage,patch,reflow soldering,cleaning and testing,etc.,combines device characteristics and package form to carry out process tests,and conducts temperature cycle,vibration,and metallographic section analysis of test pieces.The research on μBGA package device welding process technology is divided into:(1)solder paste printing process research: in the process of μBGA device assembly,the most critical process is the printing process of solder paste,which is the most critical process parameter to ensure the welding reliability of μBGA devices;(2)Research on reflow soldering process: Reflow soldering is a key step in the μBGA assembly process,and the welding curve should refer to the requirements recommended by the solder paste supplier,while taking into account the welding process characteristics of μBGA.In order to ensure the soldering quality of all pins,it is necessary to explore the reflow soldering curve suitable forμBGA devices through testing;(3)Research on environmental test verification and reliability evaluation technology: μBGA,as a board-level fine pitch device,should also pay attention to the influence of the environmental test conditions of the corresponding model on its welding quality when the soldering conditions are met,so as to determine whether the component can meet the use requirements.After completing the research of solder paste printing process,the research of reflow soldering temperature curve setting,and the research of environmental test verification and reliability evaluation technology,the final research results show that the pass rate of μBGA package device is 95%;After the environmental test or reliability test,the internal crack of the solder joint does not exceed 25% of the diameter of the solder ball,and no cracks appear in the intermetallic compound layer;The IMC(Intermetallic Compound)thickness of the solder joint meets the range of 0.5μm～4μm.Meet its special welding process requirements.