Storage and shelf life of solder pastes, wires and fluxes
A solder alloy does not age, but fluxes do: this is why pastes, flux-cored wires and liquid fluxes have a limited shelf life, while bars and solid wire do not. Storing materials correctly avoids defects that look like process problems but actually originate in the warehouse. This guide summarises the rules for each type of product.
Dickmann Srl · updated
Overview by product type
The exact temperature and shelf-life values are those given in each product's technical data sheet and on the package label: this table gives the general rules.
| Product | Where to store it | Shelf life |
|---|---|---|
| Solder pastes | In the refrigerator, package closed | Limited: see technical data sheet and label |
| Gel fluxes in syringes | According to the technical data sheet | Limited: see technical data sheet |
| Flux-cored wires | Dry place, room temperature, original packaging | Depends on the flux: see technical data sheet |
| Liquid fluxes | Cool place, away from light and heat sources, container closed | Limited: see technical data sheet |
| Solid wire, bars, solder sticks | Dry, clean place | No expiry: they contain no flux |
Solder pastes
Solder paste is a mixture of alloy powder and flux: over time and with heat the flux reacts with the powder and the paste loses printability and wettability. This is why it is stored in the refrigerator. For AIM H10, for example, the manufacturer states 6 months between 0 and 12 °C or 3 months below 25 °C.
- Before use, let the package reach room temperature without opening it, to avoid condensation on the paste.
- Do not freeze the paste.
- Do not put paste already used on the stencil back into the jar.
- Use the oldest lots first and respect the expiry date on the label.
Flux-cored wires and fluxes
In flux-cored wire the flux is protected by the alloy, but humidity and heat still degrade it: the wire must be kept dry, at room temperature and in its original packaging. Liquid fluxes must be kept closed, because the solvents evaporate and the concentration changes; alcohol-based fluxes are flammable and must be stored according to the safety data sheet.
Solid wire, bars and solder sticks
Without flux, the alloy has no expiry date. It must, however, be protected from humidity, dust and contamination, especially if it is going into a solder pot: a dirty bar brings impurities into the bath. Slight surface oxidation is normal. See our wave soldering bars and solid wire for selective soldering.
Warehouse management
- Apply the first-in, first-out principle.
- Write the opening date on paste and flux packages.
- Keep lead-free materials separate from lead-bearing ones, to avoid contaminating the baths.
- Keep up-to-date technical and safety data sheets together with the products.