When SMT production welding is performed, large and small solder balls are scattered on the substrate, and sometimes they are splashed under the components, so that they cannot be removed and brought into the device during cleaning.In the device, it rolls again due to vibration and other reasons, causing a short circuit. At the same time, these high temperature solder particles also melt the protective layer of the solder on the substrate and are then fixed thereon without being removed.
Producing solder balls is a major drawback of solder paste, the main reason are as below.
(1) The solder paste is stored at a low temperature before using. If the temperature is not raised to room temperature before using, the solder paste itself should absorb heat, and the solder will evaporate the absorbed water, causing the solder particles to scatter. In addition, if the melting temperature rises too fast, the solder particles will splash.
(2) The surface layer of the solder powder is oxidized, and heat energy which is agglomerated with other particles is not obtained at the time of soldering, making solder balls of a large size and small size remain on the substrate.
Electronic grade solder pastes are currently used in the fabrication of discrete devices and hybrid integrated circuits. It will also play an positive role in the soldering of microelectronic components.
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