DD216260A1 - ELECTROLYTE FOR THE DEPOSITION OF HALF-GLAENZING GOLD ALLOY LAYERS - Google Patents

Abstract

The invention relates to a cyanide-based electrolyte for depositing semi-glossy gold alloy layers for contact devices and for coating bond pads. The aim and the object of the invention is to find an inhibitor for a gold electrolyte operating in the weakly acidic range, which guarantees a sufficient hardening of the gold layer at high current efficiency. This object is achieved in accordance with the invention by adding to an electrolyte consisting of potassium dicyanoaurate (I) and the alkali metal salt of a weak organic acid a xanthine-nicotinate metal salt complex compound of general formula X.sub.n deep (MeY) in which X is the reacting reaction component d. Xanthinol Nicotinates, Me a metal cation, Y a Saeurerestanion and n an integer, which agree with the valency of the metal cation, mean, be implemented.

Description

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Title of the invention

Electrolyte for the deposition of semi-glossy gold alloy layers

'.5-. ''.. ·. ';^"..:.-''Field of the Invention

The invention relates to a cyanide-based electrolyte for depositing semi-glossy gold alloy layers for contact devices and for coating bond pads.

Characteristic of the known technical solutions

Known is the electrodeposition of gold alloy layers of potassium dicyanoaurate (I) electrolytes with the addition of complexes of nickel or cobalt. The complexing agents used are aminodicarboxylic acids, methenamines, EDTE and organophosphorelates.

\ '' - '"''♦ In VVP C 25 D / 241,523 a Methenaminkomplex of Co (II) or Ni is proposed (II) in combination with a 3.7 dimethylxanthine as an inhibitor of weak acid gold electrolytes.

In addition, the addition of polyhydric alcohols, and boric acid is known.

 27. "1983 * 009431

  , - 2 - ..

In the prior art, there is a drawback that by incorporating potassium in an amount of at least 0.2%, the electron work function is reduced and the reliability of contact devices is deteriorated.

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Object of the invention

The object of the invention is to find an inhibitor which increases the reliability of electrical contacts in the weak current technique with sufficient hardening of the gold layer.

Explanation of the essence of the invention

The invention has for its object to find an inhibitor for a working in the weakly acidic gold electrolyte, which guarantees a minimum potassium incorporation at high current efficiency.

This object is achieved in that an electrolyte consisting of Kaliumdicyanoaurat (I) and the alkali metal salt of a weak organic acid, a Xanthinolnikotinat metal salt complex compound of the general formula X (Me ¹ Y) is added, in which 25. '. '·'. , -

X- the reacting reaction component

of xanthine nicotinate, Me- a metal cation, Y- an acid residue anion, and η - an integer of valence

of the metal cation,

mean.

The addition of Ni (II) xanthine nicotinate is particularly advantageous. »This addition enables the deposition of gold alloy layers with a nickel incorporation of 0.57 % with a potassium incorporation of 0.0003 %. This results in very favorable TC bonding properties.

embodiment

The invention will be explained below with reference to two embodiments: Example 1

electrolyte composition

Potassium dicyanoaurate (I) 6-20 g / l

tri-Na citrate 30-60 g / l

Ni (II) xanthine nicotinate 3 - 10 g / l

The electrolyte can preferably be operated in the temperature range from 40 to 80 G. The cathodic current density with electrolyte movement is 0.2 to 0.6 A / dm at a pH of 4.5 to 5.5 (electrometrically);

Example 2

electrolyte composition

Potassium dicyanoaurate 4 - 15 g / l

tri-Na citrate 30-60 g / l

Co (II) xanthine nicotinate 2 - 8 g / l

The cathodic current density in the temperature range of 30 to 80 C is 0.3 to 0.7 A / dm. The pH is preferably 4.5 to 5.5 (electrometrically). _x

Claims (2)

, - ⁴ - · invention claim An electrolyte for depositing semi-bright gold alloy layers consisting of potassium dicyanoaurate (I) and the alkali salt of a weak organic acid, characterized in that the electrolyte is a xanthine-metal salt complex compound of the general formula X (MeY) is added, in which X- the reacting reaction component of xanthine nicotinate, Me- a metal cation,
Y - an acid residue anion and η - an integer that matches the valency of the metal cation mean· 2. Electrolyte according to item 1, characterized in that Ni (II) is added Xanthinolnikotinat.