Study On Thermal Mechanism Of Solder Bumps Reflowed By Induction Self Heating

The manufacture of solder bump is one of the key technologies for area array packaging (AAP) such as ball grid array (BGA), chip scale packaging (CSP) and flip chip (FC). The traditional global heating technologies usually make the chips and substrate suffer too much heat duration, which will cause big warpage of the component and the substrate. Huge thermal input and big warpage would reduce the reliability of the solder bumps in their service time.The application of lead-free solders aggravates the effects of these problems mentioned above for the global heating methods. The induction self heating reflow (ISHR) technology, which has the advantages of 3-D selective heating, high heating speed, high potential production efficiency and small warpage caused by different coefficient of thermal expansion (CTE), can solve the problems that can't be controlled in the global heating technologies. This thesis aims at testing the processing parameters of ISHR technology, analyzing the characters of temperature change and the metallurgical reaction, and establishing a practical thermal physical model to calculate the actual heating power of solder bump. The results can supply the theory support for the application of ISHR technology.The thesis mainly includes the following parts:(1) The heating mechanism of ISHR process have been listed, and the design and the technical parameters have been put forward.(2) According to the results of experiments on ISHR reflow process and quality analysis on solder bumps, it can be found that the solder bumps with smooth surface could be formed in a wide parameters window. Combined with the temperature change curves, the local heating characters have been analyzed. Based on interconnection experiments of actual components, the feasibility of ISHR technology of eutectic Sn3.5Ag solder ball is certified.(3) The temperature characters of ISHR are analyzed, considering about the temperature change curves obtained at the condition of different processing parameters and different positions in the solder ball and pad...