Thick-film substrates

Hybrid Sources Inc. (2009) Thick Film Substrates and Innovative Hybrid Sources Inc. Thick Film substrates and innovative hybrid assemblies , http //www.hybridsources. com/glossary-t.php... 

This multichip module was designed for military airborne communications applications where small size, high density, and low weight were critical to system performance. The module shown in Figure 1.20 is a 25.4-mm (1-in.) square package with a multilayer thick-film substrate with 125-pm (5-mil)... 

High-temperature cofired ceramic (HTCC) packages make use of thermal vias in the same manner as in multilayer thick-film substrates. The via-fill material used in HTCC packages is a refractory material such as tungsten or moly-manganese. 

A description of the application of ceramic and photopolymer technologies to achieve high-resolution electronic patterns follows. The first section discusses ceramic dielectric vias, and the second, conductive circuitry. Improved photosensitive ceramic coating compositions and more particularly, compositions that function as precursors to fired dielectric ceramics, are mainly useful in preparation of multilayer thick-film substrates. 

Other lead-free solder alloys which have been developed and evaluated by fee industry include Sn-Ag, Sn-Ag-Bi, Sn-Bi-In, and other ternary and quaternary alloys (Ref 24-33). The use of alloys containing indium (In) may be limited due to fee scarcity of indium and its high cost. The eutectic Sn-Ag alloy (melting temperature 221 °C, or 429 °F) was qualified for automotive applications in fee 1990s on ceramic thick film substrates and PWBs (Ref 3,12-15,34- 5). The microstructural characteristics of the Sn-Ag-Cu system under different reflow conditions and... 

Thin-film dielectric coatings for capacitors Thick-film substrates for hybrid circuits Glass passivation of semiconductor surfaces " ... 

Cobalt—chromium films (20 at. % Cr) exhibiting strong perpendicular anisotropy, ie, hexagonal i -axis normal to the substrate surface, have been studied (53). Fifty nanometer films are composed of columnar crystaUites and the domain size was found to be a few stmctural columns in diameter. Magnetization reversal was shown to occur by domain rotation in thick films. Thinner (ca 10-nm thick) films do not show the columnar crystaUite... 

Polymer thick films also perform conductor, resistor, and dielectric functions, but here the polymeric resias remain an iategral part after cuting. Owiag to the relatively low (120—165°C) processiag temperatures, both plastic and ceramic substrates can be used, lea ding to overall low costs ia materials and fabrication. A common conductive composition for flexible membrane switches ia touch keyboards uses fine silver particles ia a thermoplastic or thermoset polymeric biader. 

The XPS survey spectrum of a 75 nm thick film of plasma polymerized acetylene that was deposited onto a polished steel substrate is shown in Fig. 18 [22]. This film consisted mostly of carbon and a small amount of oxygen. Thus, the main peaks in the spectrum were attributed to C(ls) electrons near 284.6 eV and 0(ls) electrons near 533.2 eV. Additional weak peaks due to X-ray-induced O(KVV) and C(KLL) Auger electrons were also observed. High-resolution C(ls) and 0(ls) spectra are shown in Fig. 19. The C(ls) peak was highly symmetric. 

Tsai then applied thick films of the polyamic acid of PMDA and 4-BDAF to polished silver substrates and thermally imidized the films. The substrates were immersed into liquid nitrogen, causing the films to delaminate and XPS was used to examine the polyimide and silver fracture surfaces (see Fig. 33). The C(ls) spectra of the silver fracture surface were very similar to those of neat polyamic acid, indicating that imidization was inhibited by interaction of the polyamic acid with the silver substrate. This was evident from the observation of two peaks near... 

The gas-sensitive material in thick-film gas sensors has a sintered layer area of a few square millimeters, and about 30 im in thickness, on a ceramic substrate (Fig. 13.546). In other types of gas sensors, it is on the outer surface of a thin tube or as a sintered button (Fig. 13.54l and c). The sensor is heated tet the operating temperature of 300-500 °C by means of a resistor. 

Ultra-thin films of polyanilinc may be spin-coaled onto the ITO substrates. By studying thick films, spectra of the polymer itself are obtained. As the thickness of the polymer overlayer is reduced, some of the subtle details of the interface between the very thinnest possible polymer layer (essentially a mono-layer, in the... 

Figure 10-9. Emission spectra for a 210 nm thick film of BuEH-PPV spin-coalcd onto a glass substrate for different excitation pulse energies. Optical excitation was accomplished with laser pulses of duration 10 ns (according to Ref. [37]).

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