Abstract: Various methods have been proposed for measuring the viscosity of thermosetting polymers. It has been found that these method are generally inaccurate. A test which avoids the inaccuracies of previous techniques is proposed. In this test the heated thermosetting resin is forced at a known flow rate through a runner and through a capillary tube at the end of the runner. By measuring the pressure differential across the capillary a meaningful measure of viscosity is obtained.

Abstract: In molding integrated circuit packages voids are found in the molded plastic due to air entrapped in the charging container. It was discovered that entrapped air can be avoided if a portion of the preheated charge material has a higher viscosity than the remainder. Conveniently, this is achieved by preheating the preforms in a temperature gradient and charging the hottest preforms last into the container. The pressure causes the material at the top of the chamber to flow first, thereby expelling unwanted air through the runners ahead of the plastic flow. An effective implementation results from tilting the RF electrode in the preheating apparatus.

Abstract: An article comprised of a body having a conductor pattern on at least one non-planar and non-flexible surface thereof. The article is prepared by using a three-dimensional mask having an interior surface which is a mirror image replica of the surface of the body on which the conductors are to be formed. The surface of the body is provided with material which is capable of initiating conductor formation. The interior surface of the mask then is placed over the body and in substantial registry therewith. The mask and the body then are exposed to radiation or moving material to delineate the conductor pattern. Subsequently, the mask is removed and conductors are formed.