Abstract: A viscometer measures the rheological properties of polymers over a wide range of temperature, shear-rate and cure conditions, so that it can be used with extremely fast-changing resinous materials such as fast curing thermosets and fast crystallizing thermoplastics. The viscometer uses a mold made of three plates, clamped together during testing, with the center plate having at least one cavity (reservoir) and a slit from each reservoir to the ambient conditions outside the viscometer. Resin is injected into the reservoir in a short period of time. After filling the reservoir, the sample is heated to a test temperature through heat conduction from the reservoir wall. The heating is rapid because of the small thickness of the reservoir. The rapid filling and heating properties of the apparatus makes the rheology measurement of fast changing polymers possible. The sample is put under pressure by a piston and forced to continuously flow through the slit.

Abstract: A new method and device to encapsulate integrated circuits such as flip chips and BGA packages. A special mold to surrounds the chip to be encapsulated in a cavity, and the encapsulant is injected into the cavity at an elevated pressure, and possibly at an elevated temperature. This shortens the cavity filling time by two or three orders of magnitude, compared to the conventional dispensing process. The reliability of the package is increased by increasing the adhesion of encapsulant to the package, by controlling fillet shape through in-mold curing, and by completely filling the cavity through proper mold design and, optionally, evacuation of the cavity prior to injection. The invention also allows the use of a wider range of encapsulants, including highly viscous material, fast curing materials and reworkable materials.

Abstract: A new method and device to encapsulate integrated circuits such as flip chips and BGA packages. A special mold to surrounds the chip to be encapsulated in a cavity, and the encapsulant is injected into the cavity at an elevated pressure, and possibly at an elevated temperature. This shortens the cavity filling time by two or three orders of magnitude, compared to the conventional dispensing process. The reliability of the package is increased by increasing the adhesion of encapsulant to the package, by controlling fillet shape through in-mold curing, and by completely filling the cavity through proper mold design and, optionally, evacuation of the cavity prior to injection. The invention also allows the use of a wider range of encapsulants, including highly viscous material, fast curing materials and reworkable materials.

Abstract: An efficient numerical procedure for the simulation of Newtonian fluids with non-negligible inertial effect which satisfies the Navier-Stokes equations and the energy equation. The method simulates the molding-filling process of incompressible viscous liquid, e.g. semi-solid metal, in a thin and irregular cavity. The moving free surfaces in an irregular domain is tracked using a fixed-mesh method. The material discontinuities across the interface between air and the liquid are removed by replacing the air with a pseudo-gas which has small density and dynamic viscosity but its kinematic viscosity is the same as that of the liquid. During the filling process, the (semi-solid) liquid may solidify on the mold surface. As a result, the effective cavity thickness reduces non-uniformly according to the result thermal analysis. The Navier-Stokes equations are integrated across the remaining gap by assuming that the velocity profile (not magnitude) is similar to that in a fully-developed flow.

Abstract: A new method and apparatus for the injection molding of semi-solid materials (SSM). In this process (called Rheomolding), a superheated liquid metal is cooled into the semi-solid state in the barrel of a special vertical injection-molding machine, with the growing dendrites of the solid phase being broken into small and nearly spherical particles by the shearing force generated by the screw and barrel. Compared with the superheated liquid metal, SSM has lower temperature, lower shrinkage and a more stable flow pattern. Therefore, the rheomolding process can produce net-shape metal or metal-matrix-composite parts continuously at lower cost.

Abstract: An apparatus and method for measurement of the thermal conductivity of polymer melts is disclosed. A sample of material to be measured is placed in an elongated cylindrical container and is heated to a preselected base temperature. A probe placed in the container in contact with the sample contains a transient heating element and a temperature sensor. To determine the thermal conductivity of the sample material, the transient heating element is energized and the resulting changing temperature of the sample material is measured for a short period of time. The rate of temperature change is a measure of the thermal conductivity of the sample material at the base temperature.