The SMT surface mount process consists of three main steps, solder paste printing, component placement, and reflow soldering.
1. Solder paste printing
The solder paste is a bonding material for connecting the surface-adhesive component circuit boards. First, after the steel plate(PCB stencil) is etched or laser-cut, the solder paste is printed on the solder pads of the circuit board by the squeegee of the printing machine,in order to proceed to the next step.
2. Component placement
Component placement is the key technology and focus of the entire SMT placement process. The process uses high-precision automated placement equipment to accurately place the surface mount components on the pad of the printed circuit board.Due to the increasingly precise design of the surface-adhesive components, the spacing of the pins is also reduced, so the difficulty of the technical level of placement operations is increasing.
3. Reflow soldering
Reflow soldering is a circuit board on which a surface-adhesive component has been placed, which is preheated by a reflow oven to activate the flux, and then the temperature is raised to a needed scientific temperature(the temperature is different by Lead free and no lead free) to melt the solder paste, and the component pins are connected to the solder pads of the circuit board, then cooled to solidify the solder, that is, the surface adhesion component is bonded to the circuit board.
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