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Surface mount components are commonly available
with gull-wing, J-style and butt-lead configurations. Gull-wing style
leads are the most popular design for interconnects. While it can be argued
in some cases that a J-style lead offers a better solder fillet, in other
cases they offer no technical advantages with connectors and almost always
require more complex and expensive stampings. Butt-leads have less surface
area than is desirable for good solder fillets, a particular concern with
surface mount interconnects. Some tests have shown pull strengths of butt
joints at less than half that of gull-wing and J joints. Gull-wing style
leads are relatively easy to stamp and form on standard
and fine pitches, lend themselves to low profile constructions and have
some ability to self-align on the pads during soldering. Depending on
the insulator design, all styles allow easy cleaning of boards and visual
inspection of solder joints.
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