Abstract
Persistently growing Power QFN packages are used in various fields especially micro-electronics, aerospace, oil and gas as well. However, the particular industries is pushing forward to reduce the use of hazardous materials in the process of manufacturing and assemblies. Thermo-compression die-attach layer is perceived to be the most critical element in power QFN packages as the increase in operating temperature requires new materials with suitable thermo-chemical properties also with suitable melting points of next generation lead free die attachment material. In this situation, Hi-lead solder (RM218: Pb92.5Sn5Ag2.5) which known as high temperature material is widely being used in most semiconductor assembly for die attach, yet it deduce few reliability challenges like solder voids, the clip tilt performance and also solder splash which has been considered as major quality issue in assembly of Power QFN packages (FET die, IC die and clip attach). As a solution, sintering epoxy paste (SPC073-3: Sn96.5/Ag3/Cu0.5) is being considered as a replacement. In this case, sintering epoxy paste demonstrating excellent electrical and thermal performance for Power QFN packages which is known to be demanded in market. Thus, this study investigates the differential pastes sintering paste and also solder paste, in order to identify best die attachment material to be used in thermo-compression bonding method. Therefore, the shear strength was resulting good indication where the sintering paste was recorded 2.4 Kg/mm meanwhile the solder paste was recorded 0Kg/mm at peak temperature of 260°C. Besides of that, the pot life seems promising as the sintering paste seems to have constant viscosity of 100Pa*s throughout the 48 hours tested while, high lead solder paste records viscosity from 100Pa*s marginally increase as the time increase which effects the inconsistency of pot life. Last but not least, the voids mechanisms proves sintering epoxy paste has the same pinhole voids as its individual, but the solder paste’s pinhole voids are not same as individuals which easily can fail when the particular shear force was applied. Hence, sintering epoxy paste could resolve the quality issue by using thermo-compression bonding method and produce the better reliability than the solder paste.
Highlights
Power Quad Flat No-Lead (PQFN) package is known as plastic package surface mounted with lead pads mounted on the bottom surface of the package [1]
PQFN packages is a unique as it will be in first choice because of its high speed application where high thermal performance is demanded in various industry
Sinterable epoxy die attachment paste seems to be the best choice in building the Power QFN packages, as it is compatible with silver and gold die back, bare copper lead frames and the PPF lead frames [6]
Summary
Power Quad Flat No-Lead (PQFN) package is known as plastic package surface mounted with lead pads mounted on the bottom surface of the package [1]. Existing work and studies have disclosed the processes that includes solder alloys i.e. AuSn, PbSnAg, AuGe and AuSi as well as nano- and micro- particle sintering (regularly with Ag) apart from transit liquid phase bonding [3]. The former is divided into two categories, i.e. Transient Liquid Phase diffusion bonding (TLP) and sintered nanoparticles. Sintering particles basically are applied to delay the instruction of mass diffusion and eliminates densification diffusion at high temperature and melting point which able to stabilize according to process condition which leads to improved properties to support high temperature packages. The occurrence of electrical migration and dry migration which cause Ag to build up at cathode in dendrites form that will reach the anode that will later cause failure of the device [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
