Composite solder glasses

Most industrial glasses have linear thermal expansion coefficients between 30 10 /K (thermal shock resistant borosilicate gla.ss) and 80 to 90 lO /K (window gla.ss). In composite systems, such as used in the electronics industry for fusing (soldering) glasses to metal conductors or casing components, the thermal expansion coefficients of the glass and the metal have to be precisely matched. 

Other commercial applications of boric oxide include the lead and zinc borosihcate solder glasses discussed in Secs. 6.1.2.2 and 6.2.2, which are quite chemically durable. Boric oxide is also used in many fiberglass compositions, discussed in Sec. 6.6, Glass Fiber. ... 

Aluminum fluoride is utilized, in addition to cryolite, as a raw material in the electrolytic manufacture of aluminum (temperature of electrolyte 950°C, composition 80-85% Na AlFft, 5-7% AIF, 5-7% CaF2, 2-6% AFO, 0-7% LiF). No fluorine should actually be consumed in this process, modern plants recovering the fluorine in its entirety. Other uses are as a flux (in welding, soldering, manufacture of casts), and as a melting point depressant in glass and enamel. The aluminum fluoride capacities in Europe are given in the table below. 

Use Powder metallurgy, production of pure hydrogen (can contain 1800 cc (STP) H/cc of hydride), production of foamed metals, solder for metal-glass composites, electronic getter, reducing atmosphere for furnaces, hydrogenation agent, refractories. 

Figure 16.38 TMA of three printed circuit board samples showing the glass transitions, the melting of solder on the middle sample, and the large change in dimension (expansion) due to delamination of the composite boards at high temperature. (Courtesy of Mettler-Toledo GmbH, Analytical, Schwerzenbach, Switerzerland, www.mt.com.)...

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