Ceramic green sheet

R. A. Gardner and R. W Nufer, Properties of Multilayer Ceramic Green Sheets, Solid State Technology, (May 1974). 

Ogata, T., Masaki, T., Iguchi, Y., Tanaka, T., and Iwanaga, K., U.S. Patent 6159322, Photosensitive Ceramic Green Sheet, Ceramic Package, and Process for Producing the Same, 2000. 

With LTCCs, conductors are achieved by patterning conductive paste onto a ceramic green sheet by screen printing, then firing it simultaneously with the ceramic. The conductive material is one of the important constituent materials of LTCCs, and many characteristics are required of it so that it can meet a wide range of applications in high frequency components, wiring for substrates, and electrode terminals. 

This is achieved by screen printing conductive paste on ceramic green sheets (raw sheets of ceramic powder and organic binder) before firing, forming... 

Tanaka, T. Masaki, T Ogata, T. Ceramic green sheets suitable for semiconductor devices. Jpn. Kokai Tokkyo Koho JP 10330167, 1998 Chem. Abstr. 1998, 130, 16613. 

All of these UV-curable systems have very different chemistries than those used in solvent-based systems. Most contain a dispersant, a plasticizer (not necessary in all cases), a photopolymerizable binder, and an initiator to activate the UV curing. A typical binder/initiator system found in the literature is a polyester acrylate binder and an initiator such as 2-hydroxy-2methyl-l-phenyl-propan-l-one. The binder is a liquid low-viscosity monomer diluted into hydroxy-ethyl methacrylate. Most of the UV-curable systems contain an acrylate monomer of some sort, since they have relatively low viscosities (100 mPa s or cP) and excellent reactivity with the UV radiation. The low viscosity allows the preparation of ceramic slurries with a relatively high solids loading, and the resulting high-density green sheets have excellent mechanical properties. 

The manufacturing process flowchart of the MLCs is shown in Figure 5.1.2. Green sheet process is suitable to prepare the defect-free thin ceramic him. Thickness reduction of the dielectric layer is a most effective method to design the higher capacitance capacitor with given dielectrics and chip dimension. 

A 4mil (100 iin) Punch (bottom) and EHe (top) that are used to form vias in green sheets of ceramics. The center image is a punch holder that is used by the punch system to hold the small via punch. 

A low-volume prototype screen- and stencil-printing machine is shown in Figure 6.18. This machine is equipped with a porous stone vacuum chuck that is specifically designed for handling tape layers. Unlike a prefired ceramic substrate, the green sheets of LTCC, HTCC, or MTCC are fragile and must be handled with care however, adequate force must be applied... 

The basic manufacturing process for multilayer ceramic substrates is shown in Figure 1.3 [16]. First, the ceramic powder and organic binder are mixed to make a milky slurry. The slurry is cast into tape using the doctor blade method, to obtain a raw ceramic sheet (green sheet) that before firing, is flexible like paper. Vias for conduction between layers and wiring patterns... 

Green sheets consist of ceramic powder and binder, resin materials such as plasticizer and dispersing agent and voids. It is desirable if the various ingredients are dispersed evenly and the structure is three dimensionally homogeneous in the x and y axes and z axis. From the point of view of macro-structure, the thickness of the green sheet should be uniform (since the thickness of the green sheet is stipulated as the thickness of one layer of... 

Since the surface roughness of green sheets is influenced by the size and aggregation of the ceramic powder particles, the dispersibility of the raw materials in the green sheet can be considered to be one relevant scale. However, the surface condition of the sheets is influenced by the processing... 

Figure 6-11 The relationship between the amount ofbinder in the green sheet and the distance between ceramic particles [Ref. 19].

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