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Electrical Soldering

Solder Alloys for Electrical Soldering and Tinning

Alloys for soldering and tinning cables, cable lugs, copper braids and windings

Alloys for soldering and tinning cables, cable lugs and braids: Sn99.3Cu0.7 tin-copper alloy, SAC305 and Sn60Pb40 where permitted. For battery terminals see the battery grade alloys, for electrolytic tinning the pure tin anodes.

Why Choose Our Alloys for Electrical Engineering

Optimal electrical and mechanical performance

Low-resistance joints
A full, void-free joint keeps the contact resistance between conductor and terminal low.
Current Resistance
Joints that withstand high currents without overheating. Proper sizing for power loads.
RoHS and REACH Compliance
Lead-free alloys for equipment subject to RoHS; Sn60Pb40 only where lead is permitted (products outside the scope or exemptions). ISO 9001:2015 quality system.
Long-Term Reliability
Joints that remain stable over time, resistant to oxidation and corrosion. Reduced maintenance, maximum uptime.
Tinned copper cable lugs and braid

Recommended Alloys for Electrical Engineering

Technical characteristics for electrical applications

AlloyCompositionMeltingApplication
Sn60Pb40Sn60/Pb40183–190 °CTraditional tinning, where lead is permitted
SAC305Sn96.5/Ag3/Cu0.5217–220 °CLead-free, wiring and power electronics
Sn99.3Cu0.7Sn99.3/Cu0.7227 °CEconomical lead-free, tinning of conductors and braids
Sn96.5Ag3.5Sn96.5/Ag3.5221 °CEutectic, bright joints

Tinning of terminals, braids and conductors

In electrical engineering the alloy is often used more for tinning than for soldering: terminals, copper braids and conductor ends are dipped in a bath of molten alloy or tinned with the soldering iron, to protect them from oxidation and prepare them for soldering. The ends of flexible conductors intended for screw terminals must not be tinned (IEC 60364-5-52): there, cable lugs or ferrules are used.

Tinning baths use bars of Sn99.3Cu0.7 or, where permitted, Sn60Pb40 and Sn63Pb37; for continuous top-up, solid wire. Oxidised conductors need a more active flux, such as Impetol B (ROM1) flux-cored wires or organic fluxes, with cleaning of the residues. Flux does not remove the enamel from enamelled wires: solderable enamels are stripped in the high-temperature bath, the others must be removed mechanically.

Lead or lead-free?

The RoHS directive restricts lead in electrical and electronic equipment. Large-scale stationary industrial tools and large-scale fixed installations, for example, are outside its scope; there are also exemptions for specific uses and rules for spare parts of equipment placed on the market before the bans. Where none of these applies, lead-free alloys such as Sn99.3Cu0.7 or SAC305 are required.

UseLead-free alloysLeaded alloys (if permitted)
Wiring and connectorsSAC305, Sn99.3Cu0.7Sn60Pb40, Sn63Pb37
Tinning bathsSn99.3Cu0.7Sn60Pb40, Sn63Pb37
Motors and transformersSn99.3Cu0.7, SAC305Sn60Pb40

Flux-cored wire or solid wire?

For hand soldering of cables and cable lugs, flux-cored wires from 0.5 to 3 mm; for larger diameters and for baths, solid wire up to 4 mm with separate flux is used. For batteries see the battery grade alloys, for electrolytic tinning the tin anodes.

Electrical Soldering Applications

Typical sectors and installations

Electrical Control Panels

LV wiring, busbar connections, terminals and cable lugs on copper conductors.

Industrial Plants

Power distribution, motor connections, transformers. High-current copper joints, mechanical strength.

Lighting

LED drivers, power supplies, lamp connections. Soldering of power components, heat dissipation.

Renewable Energy

Photovoltaic inverters, string box connections, LV panels. High reliability, resistance to UV and temperature.

Soldering vs Crimping in Electrical Engineering

When to choose soldering for electrical connections

AspectSolderingCrimpingNotes
ConductivityExcellent (continuous)Good (contact)Soldering: continuous path
Mechanical StrengthHighVery highCrimp: higher tensile strength
Installation TimeMediumFastCrimping is faster
ReliabilityHigh, if the joint is not subject to vibrationHigh with a calibrated toolBoth depend on workmanship
CostLow (material)Medium (tools)Crimping: initial investment

Recommendation: soldering for permanent high-reliability connections (fixed panels, industrial plants). Crimping for fast installations, field wiring, frequent maintenance. Do not combine the two methods: a crimped terminal must not be soldered and a tinned conductor must not be crimped.

Frequently Asked Questions about Electrical Soldering

Everything you need to know about soldering for electrical installations

For equipment subject to RoHS: lead-free SAC305 or Sn99.3Cu0.7. Sn60Pb40 only where lead is permitted: products outside the scope of RoHS or uses covered by exemptions. For terminals and braids of large cross-section, dip tinning in a bath is often used.

Yes, but minimally. Quality alloys (SAC 305, Sn-Ag) have a conductivity of 10-15% that of copper. Over a short length (a few mm) the impact on total resistance is negligible. Important: clean surface, complete joint without voids.

What matters most is the contact area between conductor and terminal, not the thickness of the alloy: the alloy conducts about 10–15 % as well as copper. For high currents heat dissipation also matters: check the joint temperature under load.

It depends on the application. Soldering: permanent connection, suitable for joints not subject to vibration. Crimping: fast installation, repeatable with a calibrated tool, preferred where there is vibration. They are alternatives: a crimped terminal is not soldered and a tinned conductor is not crimped.

For alloys the reference is EN ISO 9453 (designation and purity); for lead, the RoHS directive applies with its exemptions. Installation and panel standards, such as the CEI standards or IEC 60204 for machinery, concern the design of the panel, not the alloy.

Use a suitable flux during soldering. Clean residues afterwards (IPA alcohol). Protect joints with protective varnish or heat-shrink sleeving. For aggressive environments: conformal coating or protective resins. Periodic maintenance for inspection.

Soft soldering uses tin-based alloys below 450 °C and is the technique for wiring, terminals and braids. Brazing, above 450 °C, uses silver or copper-phosphorus alloys: Dickmann supplies only soft soldering alloys.

Request Advice for Electrical Engineering Applications

Compare the lead-free alloys, choose the flux and find out about our ISO 9001 quality system. Request a quotation for formats and quantities.

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