Hits:

Indexed by:会议论文

Date of Publication:2018-01-01

Included Journals:CPCI-S

Page Number:603-606

Key Words:3D packaging; Cu6Sn5; regular grains; anisotropy; temperature gradient

Abstract:With the development of three-dimensional (3D) packaging technology, the dimension of solder joints is continuously shrinking. How to ensure the service performance of solder joints has become an important issue. As the solder joint height reduces to several microns, the total growth rate of Cu-Sn intermetallic compounds (IMCs) increases accordingly, meanwhile, whose proportion in solder joints will increase rapidly. At this point, the physics and mechanical characters of the solder joints won't depend primarily on the solder alloy, but on the IMCs. However, since the IMCs formed in solder joints have a non-cubic crystal structure, the IMC grains have a strong anisotropy along different crystal directions. Therefore, effective control of the orientation and growth behavior of IMC grains becomes a key issue in the 3D packaging fabricating. In the current study, the (001)Cu/Sn/Cu joints are fabricated by soldering under isothermy and temperature gradient (TG), respectively. Initially, the resultant eta-Cu6Sn5 grains show faceted prism textures with an intersecting angle of 90 degrees on the (001)Cu end. However, in the isothermal soldering process, the initial faceted prism textures gradually disappear. By applying a TG, the IMCs on cold end, i.e. (001)Cu end, continue to grow rapidly and maintain the regular grain morphology. Moreover, the epitaxial growth direction of the IMCs is about parallel to the TG direction. These results provide a potential way to control the morphology and growth of Cu6Sn5 grains in 3D packaging technology.