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Italian manufacturer · low-silver lead-free alloy

SAC0307 and SAC0307 with bismuth: the low-silver alloy for wave and selective soldering

Sn99Ag0.3Cu0.7, also with 0.1 % bismuth, direct from the manufacturer: bars, solid wire and flux-cored wire for wave and selective soldering

SAC0307 is a lead-free solder alloy with 0.3 % silver and 0.7 % copper: it costs less than SAC305 because it contains one tenth of the silver. On wave soldering lines it is often used in the version with about 0.1 % bismuth, which improves wetting and joint strength after thermal ageing. Dickmann produces both versions and sells them directly, with no distribution steps in between. Ideal for electronics, automotive and industrial applications. Discover also our other lead-free alloys.

Why choose the SAC0307 alloy

What you gain and what you lose compared with SAC305

Less silver, lower cost
0.3 % silver versus 3 % in SAC305: in processes that consume a lot of alloy, such as wave and selective soldering, the saving on the bath and on top-ups is significant.
Melting between 217 and 227 °C
The liquidus is about 7 °C above that of SAC305: in wave soldering the bath still runs at 255–265 °C, but the margin above the liquidus is smaller and the thermal profile must be checked.
RoHS and REACH compliant
SAC0307 bars compliant with EN ISO 9453:2020 (no. 501), with metals of purity above 99.9 %, under an ISO 9001:2015 certified quality system. The bismuth version is a composition to specification derived from alloy EN ISO 9453 no. 501.
For wave, selective and HASL
Designed for bath processes and THT components. For SMT joints heavily stressed by thermal cycling, SAC305 remains preferable.
Wave soldering with SAC0307 alloy

SAC0307 alloy technical data

Properties of the Sn99/Ag0.3/Cu0.7 alloy

PropertyValueUnitNotes
CompositionSn99/Ag0.3/Cu0.7%0.3 % silver, 0.7 % copper, balance tin; version with 0.1 % bismuth
Solidus217°CStart of melting
Liquidus227°CFully molten, about 7 °C above the SAC305 liquidus
Density7.3g/cm³Typical value at room temperature
StandardsEN ISO 9453:2020 no. 501, IPC J-STD-006-Bismuth version: composition to specification derived from alloy EN ISO 9453 no. 501
ComplianceRoHS, REACH-Lead-free alloy

Direct from the manufacturer, not from a distributor

Dickmann produces its own alloys in its own plant in Italy: SAC0307 bars, solid wire and flux-cored wire come directly from our plant, without the chain of distributors and resellers that separates customers from the large international brands. For small and medium-sized companies this means a more competitive price for the same alloy, even small lots (minimum order one 25 kg box for bars) and direct contact with the people who produce and analyse the alloy.

For bars and solid wire, which contain no flux, soldering behaviour is determined solely by the chemical composition of the alloy and its freedom from oxides. With the same composition, the process and the finished products do not change: that is why every lot comes with a spectrometric analysis certificate (spark OES) stating the content of tin, silver, copper, bismuth and impurities.

  • Manufacturer's price, with no distribution mark-ups.
  • Composition certified for every lot by spectrometric analysis.
  • Same nominal composition as the most common SAC0307 with bismuth alloys: no process change for bars and solid wire.
  • Bath monitoring over time with periodic analyses.

SAC0307 with bismuth: what it is and why EMS providers use it

Basic SAC0307 contains only tin, silver and copper. Many electronics manufacturers in Italy, however, run their wave soldering lines with SAC0307 doped with about 0.1 % bismuth: the nominal composition Sn-0.3Ag-0.7Cu-0.1Bi, which has become a de facto standard on low-silver wave soldering lines.

In such small amounts, bismuth does not change the melting range but improves the wetting and spreading of the alloy. In high-speed ball pull tests on joints aged for 500 hours at 150 °C, adding 0.1 % bismuth to SAC0307 markedly reduced brittle fractures. In our market experience, this is why the bismuth version has spread in wave and selective solder pots in place of SAC305.

VersionNominal compositionMeltingTypical use
SAC0307Sn 99 / Ag 0.3 / Cu 0.7217–227 °CWave, selective, HASL, solid wire
SAC0307 with bismuthSn balance / Ag 0.3 / Cu 0.7 / Bi 0.1217–227 °CEMS wave and selective soldering, rework, lead tinning
Sn99.7Ag0.3Sn 99.7 / Ag 0.3, copper-freeSee technical data sheetTop-up to lower copper in SAC0307 baths

Nominal values. The bismuth version is a composition to specification derived from alloy EN ISO 9453 no. 501, which allows a maximum of 0.06 % bismuth. The bismuth content can be adjusted to customer specification: state it in your quote request.

Switching supplier without changing the process

If your bath is already SAC0307 with bismuth from another supplier, you can top it up with Dickmann bars of the same nominal composition, without emptying the solder pot and without changing the machine parameters. Before switching, send us a sample of at least 250 grams from the bath: with our bath analysis we check silver, copper, bismuth and impurities and recommend the most suitable top-up alloy. We can then monitor the composition of the bath over time with ongoing analyses, at intervals agreed according to your volumes.

  • Send a sample of the bath in use and the specification of the alloy you are using.
  • Receive the analysis report with the measured composition.
  • Top up with SAC0307 with bismuth bars and send us a sample at regular intervals: we alert you in advance when copper or impurities approach the limits.

Typical wave soldering parameters

With the liquidus at 227 °C, the bath typically runs between 255 and 265 °C, with contact times of about 2–3.5 seconds depending on single or dual wave configuration. Copper in the bath should be kept between 0.7 and 1 %: above 1 % the liquidus rises and bridges and icicles increase. To bring it back within limits, top up with our copper-free Sn99.7Ag0.3 alloy, which lowers copper while keeping silver at 0.3 %. See the guide to copper erosion and bath contamination and the one on dross in wave soldering.

Available formats

  • Dixtra Electronic bars of about 1 kg for wave and selective solder pots, in 25 kg boxes (minimum order one box).
  • Solid wire from 0.5 to 4 mm on spools from 0.25 to 4 kg for automatic top-up of selective soldering machines.
  • Flux-cored wire for hand soldering, rework and soldering robots.
  • Copper-free Sn99.7Ag0.3 bars for topping up baths.
  • SAC0307 in both versions, with and without bismuth, with an analysis certificate for every lot.

Where the SAC0307 alloy is used

Bath processes and production where the cost of the alloy matters

Wave soldering (THT/PTH)
Wave soldering (THT/PTH)
Wave solder pots for boards with through-hole components: the low silver content reduces the cost of the bath and of top-ups.
Selective soldering
Selective soldering
Solder pots of selective soldering machines, with bars for filling and solid wire for automatic top-up.
PCB HASL
PCB HASL
Low-silver lead-free alloy for the HASL pots of PCB fabricators.
Industrial and consumer electronics
Industrial and consumer electronics
THT and mixed boards produced in high volumes, where the thermal cycling resistance of SAC305 or SAC405 is not required.

SAC0307 compared with SAC305, SAC405 and Sn-Cu

Composition, melting and typical use of the main lead-free alloys

AlloyCompositionMelting PointApplication Notes
SAC0307Sn99/Ag0.3/Cu0.7217–227 °CLow silver, contained cost: wave, selective, HASL
SAC0307 with bismuthSn/Ag0.3/Cu0.7/Bi0.1217–227 °CThe bismuth-doped version used on the wave soldering lines of EMS providers
SAC305Sn96.5/Ag3/Cu0.5217–220 °CThe electronics standard: SMT reflow and specifications that require it
SAC405Sn95.5/Ag4/Cu0.5217–219 °CMore silver, for high-reliability specifications; higher cost
Sn-CuSn99.3/Cu0.7227 °CSilver-free, eutectic, the most economical

💡 Nota: SAC0307 sits between Sn99.3Cu0.7 and SAC305: the small amount of silver improves wetting compared with the silver-free alloy, at a much lower cost than SAC305.

Frequently asked questions about the SAC0307 alloy

Answers from Dickmann technicians

It is the SAC0307 alloy (0.3 % silver, 0.7 % copper, balance tin) with the addition of about 0.1 % bismuth. Bismuth improves wetting and, in ball pull tests after ageing at 150 °C, markedly reduced brittle fractures of the joints; the melting range remains 217–227 °C. In our market experience it is the low-silver version most widely used on the wave soldering lines of EMS providers.

Yes, if the nominal composition is the same: for bars and solid wire only the chemical composition and freedom from oxides matter, so the process and the finished products do not change. Before switching, it is advisable to send us a sample of the bath of at least 250 grams: based on the analysis we recommend the most suitable top-up alloy and can then monitor the bath with periodic analyses.

Because you avoid the distribution chain: for the same alloy the price is more competitive, you can order even small lots and you speak directly with the people who produce and analyse the alloy. Dickmann produces SAC0307 bars, solid wire and flux-cored wire in its own plant in Italy.

By topping up with a copper-free alloy: Dickmann produces Sn99.7Ag0.3, which lowers the copper in the bath while keeping silver at 0.3 %. Copper should be kept between 0.7 and 1 %, checked with periodic bath analyses.

SAC0307 contains 0.3 % silver versus 3 % in SAC305, and 0.7 % copper versus 0.5 %. It costs less because silver is the most expensive component of the alloy. In return it has a wider melting range (217–227 °C versus 217–220 °C), leaves less margin between liquidus and process temperature and has somewhat lower static mechanical strength and thermal fatigue resistance. In drop tests on SMT joints, however, low-silver alloys perform better than SAC305.

In processes that consume a lot of alloy, such as wave soldering, selective soldering and HASL, on THT components and non-critical boards. For SMT joints subject to severe thermal cycling, or when the specification requires SAC305, SAC305 remains preferable.

Less than SAC305 for the same weight, because it contains one tenth of the silver. The difference depends on tin and silver prices: contact us for an up-to-date quote.

The liquidus is at 227 °C, but in wave soldering it runs in the same window as SAC305. Typical values: wave solder bath 255–265 °C, selective solder pot 280–320 °C and soldering iron 330–370 °C, depending on nozzle, tip and thermal mass. Always check the parameters against the technical sheets of the flux and machine.

Yes, but not with a simple top-up: the solder pot must be emptied or diluted and the bath must be checked with an analysis of its silver and copper content. Mixing different alloys changes the composition and melting range of the bath.

Yes. It is one of the low-silver lead-free alloys used in the HASL pots of PCB fabricators, together with Sn99.3Cu0.7 and the 99SnCuNiGe alloy.

Request a quote for the SAC0307 alloy

Bars, solid wire and flux-cored wire · Direct from the manufacturer

Compare SAC0307 with the SAC305 alloy, the Sn99.3Cu0.7 tin-copper alloy and the silver-free 99SnCuNiGe alloy (SN100C equivalent), or read the guide to selective soldering. Complete overview of lead-free alloys.

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