Packaging technology by Liquid Mold-UnderFill (MUF) material for the advanced mobile devices
As one approach of advanced packaging technologies, high reliability Liquid Mold UnderFill (Liquid MUF) materials and unique process will be presented here. Liquid MUF materials have the features of high adhesion, low CTE and low modulus. It is possible to alleviate the stress of the solder of each device mounted in the package, and they have excellent reliability too. These materials are adjusted the workability depending on the application. Moreover, because of low viscosity, the Liquid MUF material could be mold-underfilled with relatively lower stress to large Flip Chip devices with small gap and narrow pitch compared to the conventional solid materials. As for the processes of the liquid materials, printing, dispensing and compression molding are applicable. In this paper, the printing process, especially vacuum printing encapsulation systems (VPES) and pressure curing systems, will be mainly discussed. In addition, module package structure that achieved by these material and process development will be also explained in detail.
New Encapsulation Process for the SIP (System in Package)
System-in-Package (SiP) is a promising concept of system integration. Different semiconductor technologies, integrated passives, and other components can be integrated into a single package, without compromising the performance of separate functional blocks. However, the increase of packaging density increases the complexity of structures. Therefore, new processes and materials are needed to achieve high reliable SiP module pkg. So in this test, we tried VPES (vacuum printing encapsulation system) as underfill and encapsulation process of SiP module. The size of SiP module package is 4.84(L) times 6.15(W) times 1.32(H) mm. It contains an IC chip and several passive components such as crystals, filters, register, capacitor, etc. IC chip size is 3.5 mm SQ, thickness 0.45 mm, and the standoff height is almost 0.06 mm. In this test we compared VPES and conventional underfill and molding process. During the VPES process we used pressure cure system to reduce the internal void size. SAT (scanning acoustic transmitter), 3D optical microscope, and shadow moire analysis were done. And reliability test such as MRT and T/C was performed.
Photoinduced spin-state transition of Co3+ in the layered perovskite manganite thin film
The photoinduced effect, at different temperatures, on layered perovskite manganite La1.2Sr1.8Mn1.8Co0.2O7 thin film deposited on a SrTiO3(100) substrate has been studied using a He–Ne laser (632.8 nm) with the power of output 25 mW at low temperatures. The electrical transport and magnetic properties of the film are investigated systematically in the temperature region from 20 to 300 K. The resistance shows a significant decrease at low temperatures (T<90 K) under laser irradiation, which can be interpreted in terms of the spin-state transition of Co3+ ions. The magnetic field combined with the laser is also used to detect the photoinduced effect of the spin-glass state. The time dependence of the metastable system under several applied fields was also discussed. The system has the ability to keep a persistent memory of the magnetic history imprinted in its zero-field resistance.