Soldering processes

M. C. Pecht, ed.. Soldering Processes and Equipment, John Wiley Sons, Inc., New York, 1992. 

Fig. 1. The essence of the brazing/soldering processes (a) before brazing/soldering (b) heating to the brazing/soldering temperature, and (c)...

In any brazing/soldering process, a molten alloy comes in contact with a surface of solid, which may be an alloy, a ceramic, or a composite material (see Ceramics Composite materials). For a molten alloy to advance over the soHd surface a special relationship has to exist between surface energies of the hquid—gas, soHd—gas, and Hquid—soHd interfaces. The same relationships should, in principle, hold in joining processes where a molten alloy has to fill the gaps existing between surfaces of the parts to be joined. In general, the molten alloy should have a lower surface tension than that of the base material. 

The manufacturers stress ease of processing as a particular feature of the material. Recommended melt temperatures are in the range 320-340°C and mould temperatures are 135-165°C. Mould shrinkage of glass-filled grades is usually of the order of 0.2-0.4% in the flow direction and up to twice this value in the transverse direction. The materials are notable for their ability to withstand vapour phase and infrared soldering processes. 

Martensitic stainless steels are usually used in the softened (tempered at or above 650°C) or in the fully hardened condition (tempered at or below 250°C) so that there is no substantial reduction in corrosion resistance resulting from carbide precipitation. However, the hard soldering of knife blades can result in carbide precipitation and pitting of the blade at the area adjacent to the handle, and care must be taken in the soldering process to avoid this danger. 

There are apparently customers who soldered on ceramic capacitors in their power supplies and found the clock was just too low. They figured the capacitance was above the guaranteed upper tolerance band (a rare event with commercial ceramics ), and shipped them right back to their manufacturers. But the problem was only that as soon as the PCBs went through the soldering process, age reset (or de-aging) occurred and so capacitance rose. If only they had waited for some more time, their clocks would have been right on However, I would have preferred SMD him capacitors if stability was so important. 

The glass plates were manufactured by photoetching of a specially glass and were irreversibly bonded by a thermal soldering process [39],... 

The manufacturing process Includes photolithography, Etching, electroplating and a Novel soldering process... 

The loss of insulation resistance of a solder mask determined at elevated temperature and humidity is dependent mostly on the moisture content of the air. Elevated temperature alone does not cause a dramatic reduction of insulation resistance. The soldering process increases the insulation resistance of the solder masks examined. It is postulated that hot solder seals the surface of the solder mask, rendering a better moisture barrier. This study suggests higher insulation resistance should be obtained from solder masks with higher hydrophobic properties. 

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