Soldering terminology

Phenomenon which occurs when the temperature distribution of a circuit board is not uniform, the solder paste was not applied uniformly onto the pads, the surface of the solder powder was oxidized during pre-heating, or the solvent is partially evaporated and an uneven soldering occurred due to any of these reasons. In this case, the solder melts faster on one of the solder pads than on the other and its surface tension pulls the end of the chip down, making it protrude (see Figure). Since this condition is reminiscent of the closely spaced rows of high-rise buildings in New York, the name Manhattan effect is befitting. On the other hand, the protruding chips may also resemble a grave at times; hence the name gravestone or tombstone effect is also commonly used. Usually, this occurs when the solder has wetted only one side of the land. See also Grabstein effect.