Sn995
Sn995 Low-Maintenance, Low-Cost, Pb-Free Soldering Alloy is a cobalt-doped SnCu alloy that provides a low-cost alternative to traditional SAC305 and a low-maintenance alternative to popular low-Ag lead-free alloys like Sn100C. In addition to its low cost, it produces smoother, shinier joints and lower dross than SAC305 and other SnCu-based alloys.
Low Dross
Because of Indium Corporation’s unique manufacturing process, Sn995 bar solder exhibits much lower dross than other SnCu-based alloys.
| 260°C | Run Time (hrs) | Dross (g) | Dross Rate |
| Sn995 | 22.28 | 523.3 | 23.49g dross/hour |
| SAC305 | 19.92 | 1,303.50 | 65.44g dross/hour |
| Sn100C | 25 | 1,357.60 | 54.3g dross/hour |
Why Cobalt?
There are a number of SnCu alloys doped with minor alloy additives available in the industry today but, unlike cobalt (Co), they all have shortcomings. Also, cobalt is replenished with regular additions of the bar; no need for additional additives to maintain the alloy.
The addition of nickel (Ni) is popular, but Ni has a lower operating limit of 0.035%. Below that percentage, the benefits of Ni are lost. Co has a lower operating limit of 0.003% and a much lower risk of dopant depletion.
Bismuth (Bi) is also commonly used as a dopant; however, numerous studies show that Bi content is related to fillet lifting. This is not a risk when using Co.
Note: Converting from Sn100C to Sn995
A pot dump is not necessary to introduce Sn995 to the wave soldering process if the current process is using Sn100C. The Sn100C and the Sn995 are interchangeable alloys. By adding Sn995 to the Sn100C, the grain refiner in the Sn995 replaces the grain refiner in the Sn100C as it depletes. There is no change in the solder joint. The fill yield comparison chart shows how introducing Sn995 to an Sn100C pot will affect the hole fill yields and how that will compare to SAC305.
This conversion method can be applied to most high-Sn bar solder alternatives when converting to Sn995. A pot dump would be necessary for SAC alloys.
Hole Fill Performance
Sn995 alloy provides improved hole-fill performance when compared to other SnCu-based alloys. Using optimized process conditions and flux materials, the hole fill performance can equal that of SAC305.
Quality and Process Control
Sn995 bar and wire will comply with the requirements of ASTM B-32, J-STD-006 (formerly QQS-571F), and JIS-Z-3282. Each batch of solder alloy used to manufacture Indium Corporation’s bar solder and chips is analyzed for metallic composition and impurities. Indium Corporation will certify its bar solder to meet customer specifications with a Certificate of Compliance or provide a Certificate of Analysis upon request.
Solder Analysis
Solder pot analysis is important for maintaining solder joint quality and optimal first-pass soldering yield. By allowing a solder pot to collect too high a level of contaminants from circuit boards and components, the solder can get sluggish, causing overly large fillets, poor wetting, bridging, and expensive rework and repair. Indium Corporation’s solder analysis service allows customers to purchase individual analysis or pre-paid solder analysis mailers in bulk.