KR20010107073A - Nickel-gold alloy plating composition and process of plating same - Google Patents

Abstract

The present invention relates to a nickel-gold alloy plating composition and a plating method thereof, comprising: (i) 9 to 15 g / l nickel ion, (ii) 2 to 6 g / l gold ion, (iii) 10 to 200 g / l conductive compound and (iv) the nickel-gold alloy plating composition of the present invention containing 1 to 10 g / l of a complexing agent can provide a plating layer having excellent stability and excellent corrosion resistance, flexibility and solderability without causing environmental pollution, thereby providing a lead frame, It is usefully used for the plating of semiconductor electronic devices made of copper alloy or iron-nickel alloy materials such as visualizers, printed circuit boards and connectors.

Description

Nickel-Gold Alloy Plating Composition and Plating Method thereof {NICKEL-GOLD ALLOY PLATING COMPOSITION AND PROCESS OF PLATING SAME}

The present invention relates to a nickel-gold alloy plating composition and a plating method thereof, and in particular, a plating layer having excellent stability, excellent flexibility, corrosion resistance, and solderability by containing nickel ions and gold ions as a main component and including a conductive compound and a complexing agent. Nickel-gold alloy plating compositions that can be provided, and methods for plating them on substrates, in particular semiconductor electronic devices made of copper alloys or iron-nickel alloy materials.

Conventionally, semiconductor electronic devices made of copper alloy or iron-nickel alloy material, for example, lead frame, ball grid array (BGA), printed circuit board (PCB), and connectors ( Connectors and the like, mainly silver or tin-lead alloy plating.

However, silver plating causes problems such as discoloration of the plated portion, formation of copper oxide film, and release of cyanide compounds that cause pollution.In the case of tin-lead alloy plating, heavy metals containing a large amount of lead, which are also harmful metals, are caused. Has a problem of discharging. In addition, in order to obtain a certain level of corrosion resistance or solderability required for semiconductor electronic devices, such silver or tin-lead alloy plating requires a relatively thick plating compared to other plating, but it is necessary to increase the storage capacity of the memory in the chip. In view of recent trends in which semiconductor devices are becoming high leads, that is, high capacities, thick plating is undesirable because they can lead to adhesion between the leads.

Thus, several plating methods and compositions have been proposed to replace silver and tin-lead alloy plating.

First, when the semiconductor device is a copper alloy material, in order to improve corrosion resistance, a method of palladium or gold plating with nickel base plating and excellent conductivity thereon and efficient for soldering or wire bonding has been performed. However, in this method, due to the large internal stress due to the hydrogen embrittlement of the nickel metal itself, fine cracking occurs in the nickel plating layer in the trimming and forming process, resulting in poor solderability and flexibility. It is too expensive to have a significant increase in production costs.

In addition, in the case where the semiconductor element is an iron-nickel alloy material, if nickel is directly plated on the substrate, the adhesion strength is reduced due to the iron contained in the material, and thus copper plating and nickel plating and palladium or gold plating are performed. In this method, the internal stress of nickel metal and the price of palladium still exist, and satisfactory performance and efficiency cannot be obtained due to side effects such as poor adhesion and micro cracking caused by electrical stress between plating layers due to multiple processes.

U.S. Patent Nos. 4,436,595 and 4,591,415 disclose gold alloy plating compositions containing other metals such as nickel, cobalt, copper or zinc in addition to the main metal, gold. However, this composition contains a small amount of other metals in the range of 0.3 to 0.6%, and has a composition almost similar to that of a general gold plating composition, and thus requires corrosion resistance of nickel under plating, which is still soldered for the application of conventional nickel or nickel alloy plating compositions. The problem of poor performance and flexibility was followed.

Therefore, the present inventors have diligently researched to develop a plating solution that can replace the existing silver or tin-lead alloy plating, and as a result, a larger amount of nickel ions and a smaller amount of gold ions are the main constituents and appropriate conductive compounds and complexing agents It has been found that the nickel-gold alloy plating composition including the present invention can greatly improve the flexibility, corrosion resistance, and solderability of the plating surface while having excellent stability, and completed the present invention.

It is an object of the present invention to provide a nickel-gold alloy plating composition which can provide a plating layer having excellent stability and excellent flexibility, corrosion resistance and solderability without containing harmful substances, and a method of plating a substrate using the same.

In order to achieve the above object, in the present invention, (i) 9 to 15 g / l nickel ion, (ii) 2 to 6 g / l gold ion, (iii) 10 to 200 g / l conductive compound and (iv) 1 to 10 g complexing agent Provided is a nickel-gold alloy plating composition for a copper alloy or iron-nickel alloy substrate, including / l.

In addition, the present invention provides a method of plating a base material of a copper alloy or iron-nickel alloy material with the nickel-gold alloy plating composition at a current of 0.3 to 3.0 Ampere per Square Decimeter (ASD).

Hereinafter, the present invention will be described in more detail.

The novel nickel-gold alloy plating compositions of the present invention include nickel, gold, conductive compounds and complexing agents.

Nickel, which is a hard metal, is a metal that is usefully used to increase the corrosion resistance of a base material, and has a property of being poorly alloyed with a soft metal such as gold. Since it has not been tried yet, the composition according to the present invention based on nickel and gold has a new composition different from the existing one.

The nickel component used in the composition of the present invention is preferably supplied in the form of a salt, and representative examples of the nickel salt include nickel sulfate, nickel chloride, nickel acetate, nickel carbonate, nickel hydroxide and mixtures thereof. The concentration of nickel ions in the composition is 9-15 g / l, preferably about 13 g / l, and when the concentration is lower than 9 g / l, the corrosion resistance of the plating layer is lowered and the current efficiency is low, so that plating is not performed at low current. If the content is higher than 15 g / L, cracks may occur in the plating layer, thereby deteriorating flexibility and solderability.

The gold component used in the composition of the present invention is preferably supplied in the form of a salt, and representative examples of the gold salt include sodium gold sulfate, gold cyanide (I), tetrachloro gold (III) potassium, gold chloride and mixtures thereof. Can be mentioned. The concentration of gold ions in the composition is 2 to 6 g / l, preferably about 4 g / l, and when the concentration is lower than 2 g / l, the wire bonding and soldering properties are lowered. When the concentration is higher than 6 g / l, the corrosion resistance of the plating layer and There is a problem that glossiness is lowered.

According to the present invention, the conductive compounds used in the compositions of the present invention not only further improve the conductivity of the metal ions but also increase the stability of the composition to provide uniform plating and improved current efficiency. The conductive compound may be appropriately selected depending on the type of metal salts of nickel and gold to be alloyed and may have various acid and salt forms, and preferred conductive compounds include sulfuric acid, citric acid, hydrochloric acid, carbonic acid, acetic acid, tartaric acid, sulfamic acid and phosphoric acid, and Alkali metal salts, alkaline earth metal salts, ammonium salts, organic amine salts and mixtures thereof. The conductive compound is used in an amount of 10 to 200 g / L, and if the concentration is lower than 10 g / L, the plating layer is not plated at the low current portion and the corrosion resistance and adhesion of the plating layer are lowered. If the concentration is higher than 200 g / L, the high current portion burns. There is a problem that the surface of the plating layer is not rough and uniform.

The nickel salt and the gold salt may be sufficiently reacted with the conductive compound in advance before being added to the composition, and then added to the composition, which helps to bond the metal and the conductive compound to prevent the metals from being precipitated or neutralized in the composition.

The complexing agent used in the composition of the present invention forms a stable complex with nickel and gold to provide a stable plating composition. Representative complexing agents include gluconic acid, sodium ethylenediaminetetraacetic acid dihydrate, N, N ', N "-tritosyldiethylenetriamine, nitrilotriacetic acid and mixtures thereof, and the like, and 1 to 10 g / l, preferably Preferably, it is used in an amount of 4 to 7 g / l, and if the concentration is lower than 1 g / l, the alloy ratio is not constant and the solution may be unstable, causing precipitation. If the concentration is higher than 10 g / l, the alloy ratio is not correct. There is.

In addition, the compositions of the present invention may optionally include surface improvers and / or stress reducers.

Surface improvers are used to obtain a uniform plating surface, representative examples thereof include polyethyleneimine, polyoxyethyleneamine, polyvinylpyrrolidone and mixtures thereof, and 0.1 to 5 g / l, preferably 0.5 To 2 g / l. In addition, representative examples of the stress reducing agent include diethylene glycol, polyethylene glycol, triethylene tetraamine and mixtures thereof, and the like, and may be used in an amount of 0.05 to 2.0 g / l, preferably 0.06 to 0.23 g / l. Can be. When the concentrations of the surface improver and the stress reducer are outside the range values, there is a problem that stains, pits and pin holes are formed on the plating surface, and a cloudy plating solution is made.

The novel plating compositions of the present invention can be readily prepared by dissolving certain components and any other component (s) in water within a certain concentration range, with a specific gravity of 5 to 10 Be 'and an acidity of about pH 3 to 8 Has

According to the invention, at room temperature, the substrate to be plated and the positive electrode (e.g., platinum network) are immersed in the plating composition of the present invention, and then a current of 0.3 to 3.0 ASD (A / dm ² ), preferably 0.4 to 0.8 ASD May be flown to the substrate and the anode to form a nickel-gold alloy plating layer having a thickness of 0.07 to 0.2 μm.

At this time, the plating composition of the present invention is suitable for plating semiconductor electronic devices, such as lead frames, visualizers, printed circuit boards, connectors and other electrical components made of copper alloy or iron-nickel alloy material, the plating is It may preferably be carried out in conventional installations, in particular in reel-to-reel or cut-strip equipment.

As such, the novel nickel-gold alloy plating composition of the present invention is excellent in stability and very insensitive to impurities, which can provide uniform plating with excellent corrosion resistance, flexibility and solderability even after long use and does not cause contamination problems. .

The present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited only to the following examples.

The adhesion, solderability and corrosion resistance of the plating layer prepared in the following examples are evaluated according to the following reference examples.

Reference Example 1: Adhesiveness

The plated sample was calcined at 400 ° C. ± 5 ° C. for 2 minutes, and the plated surface of the sample was evaluated by observing with a microscope (20 ×) or visually as follows.

i) presence of blister, peeling, lifted and bleeding (none: good, present: bad).

ii) the presence of peeling and fluffing when the sample is scratched with tongs or pointed objects (none: good, present: poor).

iii) When the adhesive tape (3M Scotch tape: # 540, # 610 or # 810) is firmly attached to the sample, and then peeled off quickly, the presence of peeling off of the plated part adheres to the tape (none: good, present: bad) ).

Reference Example 2: Solderability

The plated sample was mold cured at 175 ° C. for 3 minutes and then left at the same temperature for 3 hours. The cured substrate was then held at 145 ° C. for 95 hours and then soldered for 3 seconds in Flux, Kester. The uniformity of the soldered portion was observed with a microscope (Nikkon microscope UM-2 (25)).

Reference Example 3: Corrosion Resistance

After the salt spray test (KSD 9502) was performed on the plated surface of the sample under the following conditions, the degree of damage of the plated surface was observed under a microscope (20 X) or visually; Saline concentration-5 ± 1%, saline pH-6.5 to 7.2, feed air pressure-0.7 to 1.8 kg / cm ² , spray concentration rate-0.5 to 3.0 cc / 80 cm ² / hr, temperature in the tester-35 ± 2 ℃, And spraying time-8 hours of spraying and 16 hours of suspension.

Example 1

The following components were dissolved in distilled water to prepare 1 L of nickel-gold alloy plating composition according to the present invention.

Nickel Chloride 50 g / ℓ

Tetrachlorogold (III) Potassium 7 g / L

Ammonium Sulfate 80 g / L

Ammonium Chloride 23 g / L

Sodium Ethylenediaminetetraacetate 7 g / L

Polyethyleneimine 1 g / ℓ

Diethylene glycol 0.1 g / L

The lead frame was plated at a current of 0.6 A / dm ² using the nickel-gold alloy plating composition prepared above to make an alloy plating layer of 70% nickel and 30% gold. The solderability and adhesion of the plated lead frame were measured according to the method described in Reference Examples 1 to 3, which showed even and flexible plating with 100% solderability and good adhesion and corrosion resistance.

Example 2

The following components were dissolved in distilled water to prepare 1 L of nickel-gold alloy plating composition according to the present invention.

Nickel Sulfate 60 g / ℓ

Gold Sodium Sulfate 8 g / ℓ

Ammonium Sulfate 125 g / L

Nitrilotriacetic acid 6 g / l

1.3 g / l polyoxyethylene amine

Triethylenetetraamine 0.08 g / l

The lead frame was plated at a current of 0.6 A / dm ² using the nickel-gold alloy plating composition prepared above to make an alloy plating layer of 70% nickel and 30% gold. The solderability and adhesion of the plated lead frame were measured according to the method described in Reference Examples 1 to 3, which showed even and flexible plating with 100% solderability and good adhesion and corrosion resistance.

The nickel-gold alloy plating composition of the present invention can form a plating layer having excellent stability and excellent corrosion resistance, flexibility and solderability without containing environmentally harmful components, such as lead frames, visual aids, connectors and printed circuit boards. It is useful for plating semiconductor electronic devices made of copper alloy or iron-nickel alloy material. In addition, it is efficient in terms of cost and productivity by shortening the conventional two-step process of palladium or gold plating after nickel plating to one-step process of nickel-gold alloy plating.

Claims (11)

a copper alloy comprising (i) 9-15 g / l nickel ion, (ii) 2-6 g / l gold ion, (iii) 10-200 g / l conductive compound and (iv) 1-10 g / l complexing agent Nickel-gold alloy plating compositions for iron-nickel alloy substrates. The method of claim 1, The source of nickel ions is selected from the group consisting of nickel sulfate, nickel chloride, nickel acetate, nickel carbonate, nickel hydroxide and mixtures thereof. The method of claim 1, And the source of gold ions is selected from the group consisting of sodium sulfate, potassium cyanide (I) potassium, potassium tetrachloro (III), gold chloride and mixtures thereof. The method of claim 1, The conductive compound is selected from the group consisting of sulfuric acid, citric acid, hydrochloric acid, carbonic acid, acetic acid, tartaric acid, sulfamic acid and phosphoric acid, and alkali metal salts, alkaline earth metal salts, ammonium salts, organic amine salts and mixtures thereof Composition. The method of claim 1, And the complexing agent is selected from the group consisting of gluconic acid, sodium ethylenediaminetetraacetic acid dihydrate, N, N ', N "-tritosyldiethylenetriamine, nitrilotriacetic acid and mixtures thereof. The method of claim 1, And a surface improver selected from the group consisting of polyethyleneimine, polyoxyethyleneamine, polyvinylpyrrolidone and mixtures thereof in an amount of 0.1 to 5 g / l. The method of claim 1, And a stress reducing agent selected from the group consisting of diethylene glycol, polyethylene glycol, triethylenetetraamine, and mixtures thereof in an amount of 0.05 to 2.0 g / l. A method of plating a substrate of a copper alloy or an iron-nickel alloy material with the composition of any one of claims 1 to 7 at a current of 0.3 to 3.0 Ampere per Square Decimeter (ASD). The method of claim 8, And the substrate is a lead frame, a visualizer, a printed circuit board or a connector. The method of claim 8, Method carried out on a reel-to-reel or cut-strip equipment. A plated body having a nickel-gold alloy plated layer prepared according to the method of any one of claims 8 to 10.