Surface-mount technology reflow soldering

PCX withstands SMT (surface mount technology) reflow soldering. 

Oven reflow surface-mount technology (SMT) soldering... 

Surface mounting. Surface mounting of components onto PWBs is commonly referred to in the industry as SMT or surface-mount technology. It consists of the attachment of electronic components by automated dispensing or screen printing of solder paste and adhesive onto a PWB, placement of the components, then curing the adhesive and reflowing the... 

Coleman W.E., Jean, D., and Bradbury-Bennett, J.R., Stencil design for mixed technology through-hole/SMT placement and reflow. Soldering and Surface Mount Technology, Vol. 12, No. 3, 8-12, 2000. 

Stratton, P. F, Chang, E.,Takenaka, L, Onishi, H.,Tsujimoto, Y., The Effect of Adventitious Oxygen on Nitrogen Inerted IR Reflow Soldering with Low Residue Pastes, Soldering and Surface Mount Technology, No. 13,February 1993, pp. 12-15. 

Fenner, M., Solder Paste for No Clean Reflow, Soldering and Surface Mount Technology, No. 13, February 1990. 

Hot air solder leveling (HASL) or reflowed tin on copper bond pads possess a thin intermetallic layer between the applied surface finish and the pads. During surface-mount technology (SMT) reflow, the addition of molten solder on top of this preexisting intermetallic layer will further its growth. Therefore, the TAL should be limited to minimize IMC but sufficient for good solder wetting. 

Before the widespread use of solder mask, a primary method for protecting copper circuitry was to electroplate a coating of tin or tin-lead on the copper. After component insertion, the tin plating could be liquefied with oven or vapor-phase reflow to form solderjoints.The use of solder mask over bare copper to take advantage of surface mount, wave soldering, and mixed assembly restricted the use of tin plate finishing. For simple technology product, tin or tin-lead plate and reflow remains a viable fabrication and assembly method. 

An advantage of through-hole technology is reduced cost in some appUcations. That cost benefit may be realized by lower labor costs in some parts of the world that support hand assembly, which is relatively easy with the larger components and products, and lower board densities. Even when fully automated—either by wave soldering, selective soldering, or paste-in-hole/reflow—the capital equipment and manufacturing costs can stiU be lower than those required for surface-mount assembly. 

In addition to wire harness connectors, printed circuit board-attached connectors, for automotive or electronic applications, also benefit from many of SPS s performance characteristics, including low viscosity, which helps to fill thin walls and heat resistance to maintain dimensional stability through lead-free reflow soldering operations (see Table 15.2). The trend toward miniaturization in automotive electronic control modules has increased the need for compact surface mount connector technology, as opposed to bulkier through-hole and wave-soldered alternatives. 

A decade ago, PCAs comprised little more than a through-hole PCB with wave-soldered components. Today, modest electronics products can involve an array of surface mount, chip-scale, through-hole, and electromechanical technologies. Screen-printed solder paste and reflow/wave ovens no longer are sufficient to complete the build alone. This is where benchtop dispensing comes in. 

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