Solder Paste - Application: Copper

Solder paste is a homogeneous mixture of fine solder alloy powder suspended in a flux medium, used for Surface Mount Technology (SMT) assembly to attach electronic components to PCBs.

2. Composition

Solder Alloy Powder: Typically 8592% by weight

Common types:

Sn63/Pb37 (Leaded)

SAC305 (Sn96.5/Ag3.0/Cu0.5) Lead-free

Flux Medium: 815% by weight

Activators

Solvents

Resins

Thixotropic agents

3. Physical Properties

Appearance: Gray, smooth paste

Particle Size: Type 3 / Type 4 / Type 5 (per IPC standards)

Viscosity: 150250 Pas (typical, depends on grade)

Tack Time: 48 hours (typical)

4. Application Method

Stencil printing

Dispensing (syringe)

Jet printing

5. Reflow Profile (Typical Lead-Free SAC305)

Preheat: 150200C

Soak: 60120 sec

Peak Temperature: 235250C

Time Above Liquidus (217C): 3090 sec

6. Storage Conditions

Temperature: 210C (refrigerated)

Shelf Life: 312 months (unopened)

Bring to room temperature before use (24 hours recommended)