Ceramic packages

The discrepancy between ambient temperature and the bulk-silicon chip temperature as a function of the microhotplate temperature in a DIL ceramic package is shown in Fig. 6.6. The measurement was done at room temperature, and the control voltage was increased in steps of 100 mV heating the membrane from room temperature to 355 °C. The maximum temperature discrepancy due to the heating of the microhotplate was less than 3.5 °C. 

Figure 3.33 Commercial ceramic package (a) high-voltage failure and (b) electrostatic analysis showing the high-field (3 MV/m) region.

Figure 13. Process flow for cofired multilayer ceramic packages. (Used by courtesy of Interamics.)...

The most advanced implementation of cofired-ceramic-packaging technology is the thermal conduction module (TCM) used in large-scale computers (IBM) (4, 72, 74). This package can accommodate over 100 flip-chip-bonded ICs on a 90 by 90 mm cofired ceramic substrate. The multilayer ceramic substrate contains 33 metal layers for chip pad redistribution, signal interconnection, and power distribution (Figure 14). Each chip contains 120 bonding pads, and 1800 pins are brazed to the bottom of the substrate for connection to a PWB. 

What new developments the future holds nobody knows for certain. In electronics people will try to miniaturise electric equipment even further. Non-functional, ceramic packaging will be converted into functional components. For this new ceramic materials are necessary, as are ways to process them. High-temperature superconductors will lead to magnetic levitation craft, cheap electricity and improved MRI (magnetic resonance imaging). 

Briefly trace how the demands of electronic circuit technology have impacted on the development of ceramic packaging technology. 

Knickerbocker, S.H., Kumar, A.H. and Herron, L.W. (1993) Cordierite glass-ceramics for multilayer ceramic packaging. Am. Ceram. Soc. Bull. 72, 90-5. 

Examples of the sol-gel process for ceramic powder preparation include titanate and aluminates , cuprate superconductors , ceramic packaging materials, and BaTiOs. ... 

Extraction Replication (Crystals In Fired Moly). The multilayer ceramic package that Is used by IBM has a sintering operation In which the alumlna/glass body undergoes slnterlng-wlth-a-llquld phase simultaneously with the firing of the molybdenum lands. 

First-level packages provide interconnection between the printed circuit board and the chip. These packages must have the desired number of wiring layers, provide thermal expansion compatibility with the chip, provide a thermal path for heat dissipation from the chip, and keep electrical noise and transmission delay to the minimum. The two types of packages used are plastic packages and ceramic packages. 

Figure 4 shows an example of a pin grid array (PGA), developed to accommodate IC s with 84 or more pins. The original PGA s were ceramic packages, but several techniques are now used to produce them in plastic. The PGA s can be through-hole mounted on the printed wiring board, or can be socketed and surface mounted. 

Ford Microelectronics accelerometer in a plastic package [98] e) the EG. G 1C Sensor accelerometer ceramic package [23] and f) the... 

While attempts have been made to mitigate corrosion of electronics by encapsulating the components in plastics, it is useful to note that polymers are permeable to moisture. Hermetically sealed ceramic packaging is more successful. However, care must be taken to prevent moisture and other contaminants from being sealed in. A useful common approach for mitigating corrosion of circuits housed inside a relatively large-size chassis includes the use of volatile corrosion inhibitors. 

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