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.
Filling the via hole of IC by VPES (Vacuum Printing Encapsulation Systems) for stacked chip (3D packaging)
The most important process for the development of 3-dimensional packaging, especially wafer stacking, is studied in this paper. This is the process of via hole filling; via holes require filling with conductive paste for connection or non-conductive paste for reliability. VPES (Vacuum Printing Encapsulation System) is useful for the process of filling the paste in small via holes. This process is also suitable for filling via holes of a functional substrate and glass. Various types of paste (both of conductive paste and nonconductive paste) were studied to aid the selection of paste for the requirement of packaging. It was most difficult and important that printing conditions (printing times, vacuum condition etc.) were different for each paste. Printing conditions for each paste were confirmed and the mechanisms for filling of via hole by VPES were identified. The printing condition depends on the structure of via hole (design, aspect ratio, diameter and depth etc.), also the properties of the filling paste (viscosity and thixotropic index etc.).
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.