Solder wires, solder bars, and solder pastes can be classified into hard solders and soft solders according to different melting points; they can also be divided into tin-lead solders, lead-free solders, silver solders, copper solders, etc., based on different compositions. Common shapes of solders: solders are usually processed into specified sizes for use, including sheet, block, rod, strip, and wire shapes.
(1) Wire-shaped Solder ¨C commonly known as solder wire, with rosin flux wrapped in the center, called rosin-core solder wire, which is frequently used in manual soldering with soldering irons.
(2) Sheet-shaped Solder ¨C often used for welding silicon wafers and other sheet-shaped workpieces.
(3) Strip-shaped Solder ¨C commonly applied in automatic assembly production lines. An automatic welding machine cuts a section from the strip-shaped solder for welding to improve production efficiency.
(4) Solder Paste ¨C made by mixing solder and flux powder. Before welding, the solder paste is first applied to the printed circuit board (PCB), and then welding is performed. It has been widely used in automatic chip mounting processes.