Lead-free wire is kinder on soldering iron tips

A new formulation of Pb-free solder wire is designed to minimise the leaching of soldering iron tips and reduce the cost of tip degradation common at higher lead-free process temperatures.

New from Almit Technology, SR37 - LFM-48S is a new formulation of its successful Pb-free solder wire specifically designed to minimise the leaching of soldering iron tips and reduce the cost of tip degradation common at higher lead-free process temperatures.

The new Almit cored solder wire is an enhanced formulation based around the company's proven Pb-free qualified SR37 flux chemistry paired with an innovative modified Sn, Ag, Cu alloy which gives the new solder wire its low-wear characteristics at the soldering iron tip.

Current Pb-free alloys typically cause iron tip wear at 300% the rate of traditional lead containing formulations.

In contrast, SR37- LFM-48S, extends tip life by delivering degradation rates comparable to that of conventional 60Sn-40Pb alloys, giving a more efficient and stable Pb-free soldering process.

SR37- LFM-48S, shares the same soldering abilities, mechanical properties and excellent joint strength associated with Almit's existing solder alloy used for high reliability Pb-free soldering, even after heat shock tests and 3000 hours at 60C and 90% RH.

Wear at the soldering iron tip is caused by erosion due to the high tin content of the lead free solder.

Some iron manufacturers deploy thicker ferrous plating to give longer tip life but this reduces thermal transfer.

Higher temperatures are then employed which in turn accelerate tip wear.

With the high cost of soldering iron tips, the erosion issue is a real concern and a significant consumable cost for manufacturers engaged in Pb-free hand or robotic soldering.

Key to the low-wear characteristic of SR37 - LFM-48S, is that the chemistry permits most of the flux within the cored wire to flow off the iron tip during the soldering operation, while a small amount of flux stays on the tip to maintain its condition.

The flux released from the iron tip aids the wetting process to form a stronger joint.

The special formulation also prevents the flux from charring on the tip, even at elevated Pb-free soldering iron temperatures of 380C or more.

This charring effect also contributes to the erosion of the ferrous tip plating.

This ability to release the flux from the tip delivers additional advantages.

It leaves the tip cleaner for the next joint and therefore reduces the frequency of tip cleaning.

Naturally, tip cleaning procedures typically contribute to tip wear but also impact on productivity as the tip is usually cooled by the action, so the user must wait for the iron to recover its regulated temperature before a subsequent joint can be soldered.

SR37 - LFM-48S low-leaching cored solder wire for Pb-free hand or robotic cell soldering is available now from Almit Technologies in diameters of 0.5 to 1.6mm.

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