Multilayer ceramics tape casting

For planar sensors manufactured by multilayer technology, the recently developed ceramic tape casting process was improved further [17, 18]. ZrOz powder is mixed into an organic matrix of binders, plasticizers, and solvents and is tape cast onto a Mylar supporting tape or a steel belt After drying, the ceramic tape is separated from the support tape and the flexible green tape can be punched to form individual substrates. 

Equally important as tape casting in the fabrication of multilayer ceramics is thick film processing. Thick film technology is widely used in microelectronics for resistor networks, hybrid integrated circuitry, and discrete components, such as capacitors and inductors along with metallization of MLC capacitors and packages as mentioned above. 

Tape casting is used to produce a green body which consists of a thin layer of a dried ceramic suspension. These green layers can be cut into a near-net shape and sintered to give a useful ceramic object. In addition, these thin ceramic layers can be layered to produce a multilayer structure like that of the multilayer capacitor shown in Figure... 

Next to tubes and fibers, tbin ceramic sheets are also a very interesting subject for the development of thermoplastic ceramic extrusion systems. It has been shown that it is feasible to produce ceramic sheets and films with thicknesses under 200 pm. Figure 8 shows a picture of a ceramic sheet made of silicon dioxide nanoparticles. This technique could, for example, be used for the fabrication of multilayer ceramic bodies (e.g. multilayer capacitors, structural laminates) which currently are produced using the tape casting process. Big advantages relative to this conventional process would be the recycleability of the thermoplastic feedstocks and the higher achievable powder loading. 

Development work at RCA on multilayered ceramics using tape-cast material. 

Patent filed by W. ]. Gyurk of RCA on the lamination of tape-cast ceramics to form multilayers,... 

First presentation on multilayered ceramic packages prepared from tape-cast materials H. Stetson and B. Schwartz, "Laminates, New Approach to Ceramic Metal Manufacture Part 1 Basic Process." Am. Ceram. Soc. Bull., 40 [9] 584 (1961). 

Tape casting equipment capable of manufacturing 5-micron tapes continuously for use in multilayered ceramic capacitors introduced to the marketplace in Japan and the U.S. 

The next step in part fabrication is the generation of a hole pattern in the tape-cast material. These holes are used to interconnect layers in a multilayered ceramic package or to interconnect the two surfaces of a substrate. The holes are generally circular, but they can be most any other shape. This section will address the techniques and equipment used in the via generation process. 

The basis for the production of MLC and MLCC (multilayered ceramics and multilayered ceramic capacitors) is the ability to laminate together several layers of green tape to form a structure that sinters together into a monolithic solid ceramic part. This procedure for the lamination of green tape cast-sheets was invented in 1965 by W J. Gyurk of RCA. ... 

The substrates that we have been describing are single-layer substrates. There are a wide variety of multilayered packages that perform the same function as the single-layer substrate—that is, as a carrier for components that also provide insulation of one component from another, but which occupy a smaller area since some of the layers are internal to the package. The next section will discuss these multilayered ceramic packages in some detail, since they are manufactured primarily by tape casting. 

Multilayered ceramic packages (MLC) would not exist if tape casting had not been invented. The basis for the multilayer industry is the... 

Along with the multilayered ceramic capacitors, there are many other categories of electronic ceramic materials that are active by nature— that is, they perform a function other than that of a simple insulator in the electronic circuitry. Some are conductors or semiconductors, while others act as resistors, sensors, electrooptics, or magnetic components. In this section we will describe some of the electronic devices that depend upon tape casting as a forming technique. 

In addition to the multilayered ceramic capacitors just described, many of the barium titanate-based compounds that exhibit high dielectric constants are used in single-layer tape-cast capacitor devices. Relaxor materials such as lead magnesium niobate (PMN), which are characterized by high dielectric constants, broad dielectric maxima, and low sintering temperatures, have been manufactured in thin sheets by tape casting. 

W R. Cannon, J. R. Morris and K. R. Mikeska, Dispersants for Nonaqueous Tape Casting pp. 161-74 in Advances in Ceramics, Vol. 19, Multilayer Ceramic Devices. Edited by J. B. Blum and W R. Cannon. The American Ceramic Society, Westerville, OH, 1986. 

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