▎ 摘　　要

NOVELTY - Ecofriendly graphene-tellurium nanocomposite solder comprises graphene oxide, nanowire shaped tellurium oxide, aided by weed extracts of Euphorbia hirta, where Graphene oxide and nanowire shaped tellurium oxide are used as precursors. USE - The solder is useful in soldering microelectronics packaging and assembly industry. ADVANTAGE - The solder: has melting point 140-180° C; is an eco-friendly non-toxic lead-free soldering material; easily prepared in economical manner and easily fabricated; has good mechanical, chemical and corrosion properties; has high thermal conductivity; utilizes graphene-tellurium nanocomposite which gives high power density and integration, enhances hardness and strength; and has improved shear strength and reduced solder flexibility. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for fabricating an ecofriendly graphene-tellurium nanocomposite (GTeNC) solder comprising (i) preparing Euphorbia hirtaweed extract (a) washing fresh leaves of Euphorbia hirtaby normal tap water followed by distilled water, (b) drying in shade for 10-14 days at room temperature, (c) grinding the dried leaves into fine powder using mixer grinder and stored in airtight container at room temperature, (d) preparing leaves-extract by using 20 g finely grinded Euphorbia hirtaleaves-powder employing Soxhlet extractor in distilled water as a solvent, (e) centrifuging the extracted solution, (f) filtering the above extracted solution through to remove any plant residues and stored the stock extract-solution at 4° C, (ii) fabricating graphene oxide using chemical method comprising (g) taking 2.1 wt/vol.% coal and 1.7 wt/vol% sodium nitrite in conical flask, (h) adding 90 wt/vol.% sulfuric acid with constant stirring on magnetic stirred for 19 hours at 60° C, (i) keeping above composition at constant stirring at an elevated temperature of 80° C for next 4hours, (j) obtaining 5.2 wt/vol.% nitric acid and graphene oxide (GO) as sedimentation by centrifugation at 10000 rotation/minute for 15 minutes, (k) centrifuging the above composition (step j) to remove the ions of oxidant and other inorganic impurity at 12000 rotation/minute for 15 minutes, (l) repeating the centrifugation process for 5 times, (iii) fabricating nanowire shaped tellurium oxide (m) adding 16 wt/vol.% tellurium oxide powder to 80 wt/vol.% (w/v) Euphorbia hirtaleaves extract with constant stirring on magnetic stirrer at 200 rotation/minute, (n) adding 5 wt/vol.% hydrazine hydrate under constant stirring for 1 hour, (o) adding 10 wt/vol.% sodium dodecyl sulfate, (p) stirring the above composition for 15 hours and centrifuging 8 times at 800 rotation/minute for 15 minutes with deionized water to remove hydrazine hydrate and sodium dodecyl sulfate from suspension, (q) acquiring nanowire shaped Tellurium oxide, (iv) fabricating graphene-tellurium nanocomposite solder comprising (r) adding 11.1 wt/vol.% nanowire shaped tellurium oxide and 23 wt/vol.% Euphorbia hirtaleaves extract to 67 wt/vol.% deionized water consisting of 0.5 wt/vol.% graphene oxide and sonicating for 30 minutes to acquire suspension, (s) keeping the above composition undisturbed for 40 hours, (t) Cooling the precipitate obtained in the above step at room temperature, (u) Washing the above solution 7 times with deionized water and centrifuged at 8000 rotation/minute, (v) drying the above composition at 6° C for 30 hours, and (w) obtaining the powdered graphene-tellurium nanocomposite solder.