Sn96.5/Ag3.0/Cu0.5
J-STD-006 SAC305 powder, O < 100 ppm, satellite-free T3-T8 cuts for stencil and jet printing. Custom distributions and low-Ag alternatives. Lot SEM certification.
QUICK ANSWER
SAC305 is the electronics industry's standard lead-free solder alloy — 96.5% tin, 3.0% silver, 0.5% copper — supplied as spherical powder in Type 3 through Type 8 size cuts for solder paste production. Melting at 217-219 °C, it solders virtually every consumer, automotive, and industrial electronic assembly built today, from smartphone motherboards to EV inverters.
SAC305 became the default lead-free alloy after the RoHS transition because it balances reflow behavior, joint reliability, and cost better than any alternative: the silver strengthens the tin matrix and improves thermal fatigue life, while the small copper addition reduces copper dissolution from pads. Solder paste formulators buy the powder — not the alloy — because paste performance depends on powder sphericity, oxygen content, and tight size distribution; satellite particles and irregular shapes cause printing defects and solder balling that no flux chemistry can fix.
MATERIAL DATA
Lot-level controls focus on the chemistry, particle characteristics, and process values that influence manufacturing consistency and finished-part performance.
| Element | Content | Performance Role |
|---|---|---|
| Tin (Sn) | 96.5 wt% | Wetting and conductive base of the solder joint |
| Silver (Ag) | 3.0 wt% | Strengthens matrix, improves thermal fatigue and creep resistance |
| Copper (Cu) | 0.5 wt% | Reduces copper pad dissolution; stabilizes melting behavior |
| Oxygen (O) | < 100 ppm (powder) | Critical powder spec — oxides cause solder balling and poor coalescence |
| Impurities (Pb, Bi, others) | < 0.1% combined | IPC/J-STD-006 limits for joint reliability |
Final limits can be aligned with the agreed purchase specification.
APPLICATIONS
SMT assembly is the totality of the market: every printed circuit board reflowed today in lead-free production uses SAC-family paste, and SAC305 holds the dominant share. Paste manufacturers atomize or buy powder and blend it with flux vehicles at 85-90 percent metal loading, then the paste is stencil-printed onto boards at line speeds where powder quality directly controls print definition, slump, and defect rates. Finer powder types (T4, T5) enable the shrinking pad geometries of smartphones and wearables; ultra-fine T6-T8 grades serve jet printing, micro-assembly, and SiP packaging.
Beyond standard SMT, SAC305 powder serves power electronics (where its thermal fatigue resistance suits IGBT and inverter assemblies), automotive electronics under AEC-Q reliability regimes, and repair/rework paste markets. The buying criteria everywhere are the same: certified alloy to J-STD-006, sphericity and satellite control, oxygen below spec, and size distribution certified per IPC type — because a paste line shutdown costs more in an hour than a powder lot costs in total.
BRAZING FILLER & SOLDER POWDERS
CUSTOM SUPPLY
We supply SAC305 powder in Type 3 through Type 8 cuts with certified sphericity, satellite-free morphology, oxygen below 100 ppm, and IPC size distribution per lot. Custom size distributions for jet printing, low-oxygen premium grades, and alternative alloys (SAC105, SAC0307, SAC387) are available. Export note: the 3% silver content ships as manufactured solder alloy under standard declarations; China's silver quota administration applies to silver metal, and we confirm documentation at order time — supply is routine.
We supply SAC305 powder in Type 3 through Type 8 cuts with certified sphericity, satellite-free morphology, oxygen below 100 ppm, and IPC size distribution per lot.
Custom size distributions for jet printing, low-oxygen premium grades, and alternative alloys (SAC105, SAC0307, SAC387) are available.
Export note: the 3% silver content ships as manufactured solder alloy under standard declarations; China's silver quota administration applies to silver metal, and we confirm documentation at order time — supply is routine.
MATERIAL COMPARISON
| Comparison Point | This Product | Low-Ag SAC |
|---|---|---|
| Silver content | 3.0% | 1.0% / 0.3% |
| Thermal fatigue life | Benchmark — best in class | Reduced in harsh cycling |
| Drop/shock resistance | Good | Better (softer alloy) |
| Alloy cost | Higher (silver price) | 20-40% lower |
| Wetting | Excellent | Good |
| Best use | Automotive, power, harsh service | Consumer electronics, cost-driven |
TECHNICAL FAQ
Need a different chemistry, particle range, or processing route? Our material team can review the requirement and supply window.
The five-particle rule: the smallest aperture should fit at least five particles across. Standard SMT runs Type 3; fine-pitch below 0.4 mm runs Type 4; micro-BGA and 01005 components need Type 5 or finer. Tell us your smallest aperture and we recommend the cut.
Solder balls come from oxides and satellites that fail to coalesce during reflow. Oxygen above 100 ppm and satellite content are the primary powder-side causes — our lots are certified on both, with SEM images available.
Yes — jet printing needs ultra-narrow Type 6-8 distributions with exceptional sphericity to pass micronozzles. We supply these cuts with jetting-test support.
No — solder alloys are manufactured products shipping under standard declarations. The silver quota regime applies to silver metal and unwrought forms; SAC powder supply is routine.
Cool, dry, sealed — ideally refrigerated like paste for long storage. Oxidation over time degrades reflow coalescence, so buy to consumption and rotate stock FIFO.
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