Ceramic substrate manufacturing

Figure 1.3 Typical multilayer ceramic substrate manufacturing process.

Standards for High Mlumina Ceramic Substrates for Microelectronic Mpplications, Alumina Ceramic Manufacturers Association, New York, 1971, pp. 1—12. 

Cera.mic, The ceramic substrate is made from a mixture of siUcon dioxide, talc, and kaolin to make the compound cordierite [12182-53-5]. Cordierite possesses a very low coefficient of thermal expansion and is thermal-shock resistant. The manufacturing process involves extmding the starting mixture (which is mixed with water and kneaded into a sort of dough) through a complex die to form the honeycomb stmcture. The extmded piece is dried and fired in a kiln to form the cordierite. The outside or circumferential dimension is formed by the die, and the length is cut later with a ceramic saw. 

Also in an industry where weight and space are at a premium ceramic substrates occupy a larger volume than would a unit of comparable catalytic activity manufactured using Fecralloy as the substrate. In the relatively short time that the alloy has been available for large scale evaluation it has already gained acceptance by many potential users in the automobile industry and, as a result, specialty steelmakers both in the U.S.A. and Britain are now able to offer tonnage quantities in various fabricated forms. 

The matching of expansion behavior is of the utmost importance to manufacturers of, for example, multi-layer capacitors, porcelain enameled cast iron sinks, fiber reinforced composites, light bulbs, etc. In all cases, various materials in rigid contact must have their expansion characteristics carefully matched. Inattention to this runs the risk of cracking and shattering of a light bulb at its seal to aluminum, delamination of metallic conductive leads from the ceramic substrate in a hybrid circuit, etc. By changing the composition of a constituent material, its... 

After printing the ceramic ink on ceramic substrates, the coatings are dried at about 150°C for 15 minutes. After the drying step the films are densified at about 1100°C for 15 minutes using a temperature profile which is compatible with the manufacturing process of the ceramic substrates. 

Rolls Royce 60 planar, on porous ceramic substrate materials, cells, stack, manufacturing, system... 

The number of circuits which can be placed on one silicon "chip" is restricted by the difficulty of keeping the wafer of silicon bonded to its ceramic substrate as it heats up. At present, the most frequently used packaging material is alumina which has a thermal expansion coefficient, nearly twice that of silicon. Differential expansion between the silicon and its substrate is containable in current packages but the manufacturers want to move to larger circuits, for faster computers and to reduce size and cost of the overall equipment, so differences in expansion set a limit on how large the circuits can be. The semiconductor companies have a real need for a substrate material with thermal expansion similar to that of silicon. (Table 3)... 

Nevertheless, preparation of the multilayer substrate surface is more complex and is usually carried out by the users instead of manufacturers of ceramic substrates. Simply applying a polymer layer onto the as-fired ceramic surface cannot lead to successful thin-film layers. The solvent trapped in microporosities in the conductor for vias and/or at the interface between conductor and ceramics may outgas during the reflow soldering when populating components on the finished thin-film substrate, resulting in poor adhesion of thin-film metal and dielectric at the position of vias. 

Master, R.N., Herron, L.W., and Tummala, R.R., Cofiring process for glass-ceramic/ copper multilayer ceramic substrate, IEEE Transactions on Components, Hybrids, and Manufacturing Technology, Vol. 14, 780-783, December 1991. 

The original equipment manufacturer (OEM) or module or component manufacturer may perform testing of the ceramic substrate, the assembly using the substrate, or depending on the test requirements at the lower levels, may not perform any further testing imtil the end item goes to final test. 

The lead-on-substrate MCP could also be implemented using a cofired ceramic package with the leads brazed on and finished by cover coating with a suitable encapsulant or hermetic seaUng of the assembled ICs. Chapter 7 of Ref. 7 gives a detailed discussion of the cofired multilayer ceramic package manufacturing processes. 

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