Solder pastes used in electronics manufacturing printing processes are thixotropic.

Solder pastes may also function as a temporary adhesive for keeping electronic parts in place before and during soldering.

One of the major differences between lead-containing and lead-free solder pastes is the "flow" of the solder in its liquid state.

Viscosity - especially important for solder pastes, which have to be easy to apply but also thick enough to stay in place without spreading to undesired locations.

Generally, solder pastes are made of a tin-lead alloy, with possibly a third metal alloyed, although environmental protection legislation is forcing a move to lead-free solder.

Solder pastes are classified based on the particle size by JEDEC standard J-STD 005.

In most countries, "no-clean" solder pastes are the most common; in the United States, water-soluble pastes (which have compulsory cleaning requirements) are common.

According to JEDEC standard J-STD-004 "Requirements for Soldering Fluxes", solder pastes are classified into three types based on the flux types:

However it is highly susceptible to corrosion and oxidation in air, therefore zinc-containing alloys are unsuitable for some purposes, e.g. wave soldering, and zinc-containing solder pastes have shorter shelf life than zinc-free.

YCTC's other product lines include BGA spheres (both Pb and Pb free), Solder Paste, SMT Flux, and Semiconductor Flux.