Wave soldering

Most commercial wave soldering machines have a preheating section before the PCB or assembly is immersed into the solder wave, the thermal shock is reduced As the ambient temperature has already been raised before the solder wave, the thermal gradient in the reed switch seal is reduced. 

Resins are used in electromc/electncal applications (connectors, circuit boards that are vapor and wave solderable, microwave transparent radomes, integrated circuit chip carriers, miniature switches, explosion proof enclosures, lamp reflectors, and high-precision fiber optic components). Polyetherimide is used for medical components (hat require all forms of sterilization. Other uses are found in the transportation field, dual-ovenable cookware, as well as bearings, fasteners, and advanced composites. 

Thin ( 2 /mi) layers of nickel and tin are electroplated over the silver termination, the former to act as a barrier preventing dissolution of the silver during the subsequent wave-soldering operation when the chips are surface-mounted onto a substrate. The tin layer ensures good wetting of the termina tion by the solder. In the case of the BME capacitor (see below) the termination is copper fired on under reducing conditions and covered with an electroplated layer of nickel. 

The mounting of SMD components onto PCBs or flexible substrates demands a certain amount of interconnection material (solder or conductive adhesive) to form a correct joint. In contrast to wave soldering, where heat and material (molten solder) are provided simultaneously during the soldering... 

Flow soldering, see Wave soldering Flow time, determination of, 1631 Fluid-flow switches, 1902... 

Clean Water Act, 595 water permits, 596 Water systems, 1581 Wave soldering, 423, 424, 429 WBS, see Work breakdown structure WBT (Web-based training), 940 Wealth, creation vs. preservation of, 755 Web-based procurement, 262-263 Web-based programming, 76-79 Web-based training (WBT), 940 Web browsers, 240, 244-245 Web pages, 245 Web security protocols, 734 Web servers, 256 Active Server Pages, 79 application program interfaces, 78 Web stores, 262... 

Surface-mount technology replaces previous methods of inserting component leads into plated through-holes of PWBs, wave soldering from the back side to flow solder into the holes, and simultaneously forming both mechanical and electrical connections. SMT is highly automated and currently the most widely used production process for the assembly of single-layer, double-sided, and multilayer circuit boards. 

Figure 5.1 Representation of SMT for (a) wave soldering and b) reflow soldering.

In general, standard industrial cyanoacrylates do not operate effectively above 180°F (see Fig. 4). However, the new allyl types of cyanoacrylates can operate as high as 480°F before the bond loses sufficient strength to be operationally effective (see Table 2). Allyl cyanoacrylates for metal-bonding applications have proven effective in wave solder and under-hood (automotive) applications. In Fig. 4, bonded assemblies are cured at room temperature for 24 h. The assemblies are heated for 2 h and tested hot. 

Dymax 911/ urethane acrylate Dymax 0.12 3,000/N/A UV light or heat <10 sec Strain relief and wire/parts tacking (PCBs) where resistance to wave-solder profiles is required... 

Electronic chips are temporarily bonded with a 1-second UV-curing adhesive. The bonds hold the chip to a PC board prior to wave soldering. The adhesive must continue to bond during the soldering process, which could reach up... 

Optimization is an activity carried out in almost every aspect of our life, from planning the best route in our way back home from woik to more sophisticated approximations at the stock market, or the parameter optimization for a wave solder process used in a printed circuit board assembly manufacturer optimization theory has gained importance over the last decades. From science to applied engineering (to name a few), there is always something to optimize and of course, more than one way to do it. 

The printed circuit boards and the various electronic components to be added to it are cleaned, trimmed and sorted. The components are then mounted on to the printed circuit board ( stuffing ). This can be done either by hand or by automated surface mount machines. The parts are then soldered on to the board, by immersion in wave solder baths, or by hand. Excess solder and wire is removed by hand in a touching-up process. The final product is marked and tested in a quality control check. 

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