Reference

Aqueous solution of thallium-containing composition and its use in removing deposits of gold, palladium or palladium-nickel from supports

Aqueous solution of thallium-containing composition and its use in removing deposits of gold, palladium or palladium-nickel from supports. Fletcher, Augustus; Moriarty, William L. (American Chemical and Refining Co., Inc., USA). Ger. Offen. DE 3435799 A1 11 Apr 1985, 21 pp. (German). (Germany). CODEN: GWXXBX. CLASS: ICM: C09K013-12. ICS: C23F001-00. APPLICATION: DE 84-3435799 28 Sep 1984. PRIORITY: US 83-537945 30 Sep 1983. DOCUMENT TYPE: Patent CA Section: 56 (Nonferrous Metals and Alloys) Section cross-reference(s): 76 Au, and/or Pd or Pd-Ni alloy [66010-90-0] coatings and/or electroplates are removed from the substrate, used in electronic industry, by an aq. soln. contg. nitrobenzoic acid derivs., such as chloronitrobenzoic acid, alkali nitrobenzoate, and their mixt. ~8-30; cyanides, such as KCN 40-135; Th (I or III) compds. such as Tl nitrate 0.03-0.1; and optionally a Pb compd., such as Pb acetate [15347-57-6] 0.08-0.3, and KOH 4-15 wt. parts for pH control (11-13) to obtain 0.025-0.075 g Tl ions/L and a dissoln. rate of 31 m/min at 18-55, preferably 25-35°. The preferred components are Na m-nitrobenzoate [827-95-2], 2-chloro-4-nitrobenzoic acid [99-60-5], and TlNO3 and the surface layer is Au vapor deposited on Pd. The process is characterized by min. contamination and improved recovery of precious metals. Thus, Pd coating on Ni was removed by an aq. soln. contg. Na m-nitrobenzoate 17.6, KCN 88, KOH 8.8, Pb acetate 0.176, and TlNO3 0.066 g/L at resp. rates 1.45, 2.44, and 2.64 m/min at 21, 38, and 54° vs. 0.015, 0.2, and 0.29 with Tl ions. The etching rate was inferior when As, Te, Sb, Al, Na, Bi, and In substituted for Tl. The soln. is economical, causing no health hazard, and the mixts. have a long storage time.

Process for forming a metallurgical system comprising a bottom layer of nickel and a top layer of gold

Process for forming a metallurgical system comprising a bottom layer of nickel and a top layer of gold. Adwalpalker, Avinash Sripad; Harvilchuck, Joseph Matthew; Ranalli, Joseph Rocco; Rich, David Willia (International Business Machines Corp. , USA). Eur. Pat. Appl.Some commonly used reagents like 827-95-2 and 7440-02-0 are used in this experiment. EP 203423 A1 3 Dec 1986, 8 pp. DESIGNATED STATES: R: DE, FR, GB, IT. (European Patent Organization) CODEN: EPXXDW. CLASS: ICM: C04B041-90. ICS: C04B041-91. ICA: H01L021-48. APPLICATION: EP 86-106186 6 May 1986. PRIORITY: US 85-735040 17 May 1985. DOCUMENT TYPE: Patent CA Section: 76 (Electric Phenomena) Section cross-reference(s): 56 The process involves depositing Ni on a semiconductor or insulating substrate, forming a thin Au layer over the Ni, chem. stripping the Au layer, depositing thick Au over the Ni, and diffusing the thick Au into the Ni. Stripping the thin Au layer prior to subsequent deposition of a thick Au layer results in a 25% greater av. bond pull strength for the metallurgical system. .