Juotepasta

Juotepasta, also known as solder paste, is a material used in electronics manufacturing to join electronic components to a printed circuit board (PCB). It is a suspension of fine solder particles in a flux vehicle. The solder particles are typically made of a tin-lead alloy, although lead-free alternatives are increasingly common. The flux vehicle is a chemical compound that helps to clean the surfaces to be soldered, prevent oxidation, and promote the flow of molten solder.

Juotepasta is typically applied to the PCB using a stencil or a syringe. The stencil is a thin sheet of metal with precisely cut openings that align with the pads on the PCB where components will be placed. The paste is squeegeed over the stencil, filling the openings and leaving a precise amount of solder paste on each pad. For smaller production runs or specialized applications, the paste can be applied directly using a syringe.

Once the paste is applied, the PCB is passed through a reflow oven. The oven heats the PCB and the juotepasta in a controlled manner. Initially, the flux in the paste becomes active, cleaning the surfaces. As the temperature increases further, the solder particles melt and coalesce, forming a strong metallurgical bond between the component leads and the PCB pads. After cooling, the flux residue is usually cleaned off. Juotepasta allows for the simultaneous soldering of multiple components, significantly increasing the efficiency of electronics assembly.