Tape Characterization and Analysis

Many types of equipment are used for light transmission analysis, all of which center around the same common principle. A source on one side of the tape transmits light through the tape, which is measured by the detector of choice on the other side. Quite often, the detector of choice is the human eye. Based upon what is seen, defects can be marked and either removed from the tape or simply avoided during 

Analysis of defects in thicker tapes ( 200 to 250 pm [ 0.008 to 0.010 in.]) tends to be limited to surface defect identification. Since light cannot transmit adequately through the thicker tape, light is 

Profiling in this manner is not limited to thickness alone. A good case can be made for the importance of mass uniformity in many tapes. Systems actually exist in which mass uniformity is a more critical parameter than thickness uniformity. Regardless of the system, mass uniformity within a cast layer has great importance, since it affects shrinkage uniformity, density gradients, warpage, electrical properties and the like. 

The next step in the processing of tape-cast materials is to punch the desired shape in the area defined by the x and y directions. Most production facilities use punch-and-die sets in either a hydraulic or a mechanical press. The shaping process usually is divided into two separate functions that are sometimes combined in simple parts. These procedures will be described in the next sections. 

The design of blanking tools is an art in itself. For most ceramic tape punching, the clearance between the punch and the die is on the order of 38.1 pm (0.0015 in.), and most corners have a small radius on the order of 0.254 mm (0.010 in.). 

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