Ceramic printed circuits

Table 4.4 lists commercial cleaning solutions currently used in the electronics industry for cleaning printed-circuit boards, assemblies, ceramic printed circuits, thick-film interconnect substrates, electronic components, wiring harnesses, and stencils and screens (used in applying adhesives and solder pastes). 

After quatemalizing the copolymer of the light crosslinkable monomer, 4 -methacryloyl oxycalcon with 1-bromo propane, a comb-shaped gold electrode is either deposited or painted onto a baked ceramic printed circuit board, and by crosslinking this with light, a moisture-sensing film can be produced. 

Metal powder—glass powder—binder mixtures are used to apply conductive (or resistive) coatings to ceramics or metals, especially for printed circuits and electronics parts on ceramic substrates, such as multichip modules. Multiple layers of aluminum nitride [24304-00-5] AIN, or aluminay ceramic are fused with copper sheet and other metals in powdered form. The mixtures are appHed as a paste, paint, or slurry, then fired to fuse the metal and glass to the surface while burning off the binder. Copper, palladium, gold, silver, and many alloys are commonly used. 

It is unusual to be able to And one capacitor to handle the entire ripple current of the supply. Typically one should consider paralleling two or more capacitors (n) of I/n the capacitance of the calculated capacitance. This will cut the ripple current into each capacitor by the number of paralleled capacitors. Each capacitor can then operate below its maximum ripple current rating. It is critical that the printed circuit board be laid out with symmetrical traced to each capacitor so that they truly share the current. A ceramic capacitor ( 0.I pF) should also be placed in parallel with the input capacitor(s) to accommodate the high frequency components of the ripple current. 

Silicon shows a rich variety of chemical properties and it lies at the heart of much modern technology/ Indeed, it ranges from such bulk commodities as concrete, clays and ceramics, through more chemically modified systems such as soluble silicates, glasses and glazes to the recent industries based on silicone polymers and solid-state electronics devices. The refined technology of ultrapure silicon itself is perhaps the most elegant example of the close relation between chemistry and solid-state physics and has led to numerous developments such as the transistor, printed circuits and microelectronics (p. 332). 

Pricing as well as reliability considerations have led to an almost exclusive use of Si-based (i.e. Si and SOI) micro machined devices. Packaging and assembly has focused on ceramics (A1203, AIN, Low Temperature Co-fired Ceramics LTCC), Printed Circuit Board (PCB-) and Surface Mount Device (SMD-) technology and multichip modules (MCM s). 

Laminate materials, properties of, 17 844t Laminates, 26 752-754 electrical, 10 453—451 fabrication of, 20 112 polyimide, 20 285 printed circuit board, 17 843 strength of, 26 782-783 Laminating, ceramics processing, 5 655 Laminating resins, amino acid resins, 2 630-631... 

BaTiOj powder is used widely to make electronic components such as layered capacitor, printed circuit block, integrated circuit and piezoelectric ceramic etc. Moreover, it can be used in the field of computer and mobile telephone and satellite communications. 

Apart from obvious dry cleaning applications, potential applications of C02-based microemulsions include (i) printed circuit board cleaning, (ii) extraction of contaminants from soils, (Hi) cleaning of polymers, foams, aerogels, porous ceramics, and laser optics, (iv) regeneration of activated carbon beds or catalysts, and (v) the separation of dyestuffs from textiles. 

It can be used to deposit metal on nonconduc-tive surfaces, such as plastics, glass, or ceramics. Some proper pretreatment steps are needed to activate these surfaces. The metallizing of printed circuit board is one such example. 

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. 

When molded or premolded packages cannot be used for whatever reason, for example, a need for hermetic sealing, modules using ceramic substrates (or PCB-printed circuit board) offer almost unlimited flexibility. They can be used for simple multichip modules containing two or more elements (e.g., a sensing element and an evaluation circuit), may include external components, or may be used to construct complete systems. Stress-optimized package configurations for sensitive microsystems and sensors are no problem (Fig. 5.8.4). 

A very general question within this modular concept is the choice of circuit board and connection technology. Each pathway in Figure 5.8.7 corresponds to a possible way of building a sensor. Metal packages can be welded directly onto metal inlay parts, and ceramic modules can be directly bonded. All the illustrated modules contain a printed circuit board (PCB). 

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