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Tin-copper solder commodity

Tin-copper solder denotes commercially supplied soldering material described as Sn-Cu, rather than elemental tin or copper, a mineral species, or a documented waste stream. Jadhav and colleagues studied material supplied by Taiwan-Solid Enterprises Limited; their methods do not establish a prior service life or recovery from discarded equipment. They report nominal Sn-Cu composition as 63-37%, which is retained as reported rather than corrected to a conventional alloy formulation. Their surface observations suggest a tin-rich coating and a copper-containing interior, so this record does not assert homogeneous bulk alloy composition. Evidence applies to those experimental pieces, not every product sold under the Sn-Cu solder description. No constituent criticality designation is inherited.

Microbial & Biochemical Mechanisms (1)

Laboratory copper and tin leaching with an Acetobacter culture preparation

bioleaching Microbial

The study reports dissolution of copper and tin when Sn-Cu solder pieces were exposed to a preparation from an acid-producing Acetobacter culture. The observed endpoint is dissolved metal measured by ICP-OES, not an isolated recovered product. Acid-mediated leaching is the authors' interpretation; the experiment does not isolate a causal contribution from newly produced acetic acid or establish that living cells were required during leaching. It is a laboratory observation, not industrial deployment or a demonstrated treatment of end-of-life solder.

Experimental Context & Analytical Limits:
Commercial pieces were cut to 3 mm, rinsed with water and 75% ethanol, and dried. The microbial arm used 100 mg Sn-Cu solder with 4 mL of culture preparation at 30 degrees C and 150 rpm for 30 h. Methods describe culture grown for 24 h at 30 degrees C and 150 rpm in yeast-glucose-ethanol-acetic-acid medium; results instead call the leaching preparation a collected culture supernatant, without specifying a cell-removal procedure. Biomass presence and viability during leaching therefore remain unresolved. The paper names Acetobacter sp. TISTR 102 but attributes supply to BCRC in Taiwan without a BCRC accession. No species or strain CURIE is assigned to that unauthenticated experimental culture. Experiments were performed in three sets; the error-bar statistic and independence of those sets are not defined. An uninoculated-medium control and a matched acid-only control for this microbial preparation are not reported.
Curated Evidence Points:
Methods on pp. 2-3 and the microbial subsection on p. 6 with Figure 7 on p. 7 support time-dependent copper and tin solubilization in the reported culture preparation. The numerical extraction percentages are not adopted as reusable yields because the nominal feed composition and denominator verification are insufficiently resolved. The study's chemically supplied acetic-acid experiments and Figure 8 surface microscopy are separate arms, not direct evidence for microbial mineralization or cell contact.
The medium already includes acetic acid, and the reported culture acidity was estimated by acid-base titration with underlying data not shown. This does not independently quantify newly biosynthesized acetic acid. The chemical-acid comparison used different acid strengths and, in the low-strength series, different liquid loading, preventing a matched estimate of biological benefit. Figure 8 and pp. 7-8 describe a tin-rich outer layer and a copper-containing interior rather than independently establishing the reported bulk composition. The article's comparison with a 2014 fungal study is secondary discussion; its original full methods were not available for acceptance here.
The official catalogue currently identifies TISTR 102 as Acetobacter pasteurianus and records its historical Acetobacter aceti name. This narrows the catalogue identity, but does not resolve the paper's BCRC supply statement or prove that its experimental culture was the authenticated TISTR deposit.

Sources & References

  1. jadhav2017: Jadhav U, Su C, Chakankar M, Hocheng H (2017). Acetic acid mediated leaching of metals from lead-free solders. Bioresources and Bioprocessing 4:42. DOI 10.1186/s40643-017-0173-5. Complete ten-page original: materials and culture methods on pp. 2-3; microbial leaching result on pp. 6-7 and Figure 7; separate chemical-acid SEM/EDS experiment on pp. 7-8 and Figure 8.
    https://doi.org/10.1186/s40643-017-0173-5 (accessed 2026-10-16)
  2. tistr102: Thailand Institute of Scientific and Technological Research, Culture Collection. Bacterial catalogue entry TISTR 102: Acetobacter pasteurianus, originally deposited as Acetobacter aceti; original number No. 24 DMKU B-45. Catalogue identity does not independently authenticate the culture used in Jadhav et al.
    https://www.tistr.or.th/tistr_culture/cdetail.php?tno=102&type=b (accessed 2026-10-16)

Curation History

Timestamp Curator Action Summary
2026-10-16T08:06:49Z codex (GPT-6; codex) CREATE Created a commercial solder product record with bounded culture-associated leaching evidence and explicit feed, strain, biomass, control and outcome uncertainty.

Record source: data/records/tin-copper-solder.yaml