JPS5842766A - Adjustment of boron content in non-electrolytic nickel-boron deposit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to electroless nickel boron deposits with high boron content. More specifically, the bath to be used is
A borane reducing bath with relatively low p'H and relatively low temperature, said bath containing a source of zirconyl and/or vanadyl ions to precipitate a high percentage of boron.

Electroless co-deposition of nickel and boron is accomplished by including the support in an electroless nickel bath containing a source of nickel ions and a borane reducing agent. When compared to substantially pure nickel deposits of up to 999% nickel,
In order to increase the hardness of the precipitate, it is often desirable to form a precipitate with a relatively high boron content. However, traditionally, borane reducing baths have been severely limited in their ability to control the percentage of boron that can be formed in the co-precipitate, and have been susceptible to the formation of co-precipitates with relatively high boron contents, on the order of 2% by weight or more. It is inappropriate for These borane reduction deposits are generally limited by the bath pH and the stability of the bath borane reducing agent.

More specifically, as the pH of the borane reduction bath decreases, the percentage of boron co-deposited with nickel increases. However, since borane hydrolyzes at low pH values, the borane reducing agent begins to lose stability and is thus rapidly consumed as the pH decreases below 4.

Borane-reducing electroless nickel baths that form precipitates with high boron content must have low pH, but low pH baths consume boron reducing agent at excessive rates that are commercially unacceptable. Therefore, although the boron content of the boron-reduced co-precipitate can be increased by lowering the pH by 7, this ability is limited to a commercially acceptable rate when the pH is lowered to a level that produces precipitates of high boron. limited by the fact that it is consumed in Generally, a commercially viable borane reduction bath in terms of acceptable levels of borane consumption should have a pH well above 5.

The boron content of the nickel-boron electroless deposit can be increased by using borohydride ions as the reducing agent in the bath, rather than a boron reducing agent; pH greater than 9
Precipitates with high boron content are formed only when operated at temperatures above 0°C. These are relatively harsh conditions and are undesirable for maintaining commercial electroless plating operations. However, the borohydride reduction bath
When lowered to a pH below 2, the bath undergoes spontaneous solution decomposition.

According to the present invention, we achieve what is recognized as a high boron percentage in excess of about 2% boron in electroless nickel-boron deposits from boron-reducing electroless deposition baths, and avoid the use of borohydride ions. A method has been discovered that avoids the high pH and high temperature conditions associated therewith. Baths according to the invention are borane reducing and contain relatively moderate temperatures and moderate pH. Such a bath according to the invention comprises a source of zirconyl ions and/or vanadyl ions within a borane reduction bath.

Accordingly, it is an object of the present invention to provide improved electroless nickel baths, products and methods in which the nickel-boron deposit is characterized by a relatively high boron content.

Another object of the present invention is 1. an improved electroless nickel deposition bath that contains a boron reducing agent and forms a deposit having a relatively high weight percentage of boron.

Another object of the present invention is to provide an improved electroless deposition system in which a bath having a moderate pH and a relatively moderate temperature forms a nickel-boron co-precipitate having a boron content on the order of 2% by weight. be.

Another object of the invention is an improved electroless bath for depositing nickel deposits having increased hardness than that of substantially pure electroless nickel deposits.

These and other objects of the invention will become apparent from the detailed description that follows.

According to the present invention, an electroless nickel bath is provided in which a nickel-boron deposit is formed on a support and includes a boron deposition enhancer such as zirconyl ions, vanadyl ions or a combination thereof, and a boron reducing agent and a nickel source. provided.

Other typical electroless nickel bath components may be included, such as complexing agents, stabilizers, buffers, and the like.

It is believed that the boron precipitation enhancer provides additional stability to the boron reducing agent in the bath while also increasing boron precipitation ability at moderate pH values. The zirconyl ion boron precipitation enhancer adds zirconyl ion (Zr
Compounds that liberate O+), such as zirconyl chloride ions (ZrOCA!2.8) (20), are therefore added. The vanadyl ion (■0++) boron precipitation enhancer is vanadyl sulfate or vanadium ochinosulfate (VOSO
4.2H20) or other vanadyl salts, as well as by vanadates such as sodium metavanadate, which oxidizes organic compounds in the bath, which are reduced to vanadyl ions. is supplied into the bath.

The boron precipitation enhancer is included in the bath at a concentration that has a lower limit at which the particular enhancer will increase the percent boron precipitation and an upper limit determined by economics and bath stability considerations. In accordance with the present invention, the enhancer is at least about 0.0
0.005 mol/l. Typical concentrations of boron precipitation enhancer in the bath are at least 0.0005 mol/l, preferably at least about 0.0007 mol/l,
Most preferably at least <0.001 mol/l. Usually, these boron precipitation enhancers are added at 0.5 mol/1
It is not necessary to combine with a bath concentration of more than 3'x, preferably the concentration is less than 0.1 mo/L-/1.

Boron reducing agents utilized in baths according to the present invention include bath soluble boron sources such as amine borane, lower alkyl substituted amine borane, and nitrogen-containing heterocyclic borane such as pyridine and morpholine borane. in general,
Alkylamine borane, especially dimethylamine borane, is preferred. The concentration of reducing agent in these baths is sufficient to effect adequate reduction and is also cost effective for reducing the nickel cations within the bath.

Typical minimum concentrations are at least about 0.001 mol/l
, more usually at least 0.005 mol/l, but 1
It can contain as much as mol/l, but usually about 0
．． It is necessary to contain 1 mol/l or less.

The nickel source for these baths is a bath-soluble nickel source, such as sulfate, chloride, sulfamate, or other anion compatible with the electroless nickel system. The concentrations utilized are typical of electroless nickel plating baths and are on the order of between about 0.001 mole/l and about 0.5 mole A.

As in most electroless nickel plating baths,
These baths often contain a complexing agent, and almost any type of complexing agent is suitable, and the complexing agent is advantageous in terms of availability, economy, and increased boron content of the precipitate formed by the bath. In addition to that, the choice can be made depending on the desired properties of the particular bath. Complexing agents are generally bath-soluble carboxylic acids and bath-soluble derivatives thereof, such as hydroxy-substituted carboxylic acids, amino-substituted carboxylic acids, and bath-soluble derivatives thereof, such as bath-soluble anhydrides, salts or esters. be.

Examples of other complexing agents are U.S. Pat. No. 4,019.910 (
It is an ester complex of a polyhydric compound formed by the reaction of ochic acid with a polyhydric acid or alcohol, as described by K. Mallory. Examples of other complexes are pyrophosphoric acid and its derivatives and organophosphorus complexing agents such as phosphonates.

Examples of complexing agents for specific hydroquine-substituted carboxylic acids are citric acid, glycolic acid, lactic acid and malic acid, while examples of oxidizing agents for amine-substituted carboxylic acids are β-alanine, aminolead acid, aminodiacetic acid, and Amino acids, e.g. α
- alanine, aspartic acid, glutamic acid, gly7ine, leucine, serine, trio7no, and valine. Complexing agents that fall within the category of ester complexes of oxyacids and polyhydric acids or alcohols include oxyheptadic acids containing at least divalent hydroxyl groups and about 4 to about 15 carbon atoms per molecule. Includes ester complexes prepared by reaction with carbo/acid or alcohol compounds. Examples of typical suitable polyhydric compounds are carboxylic acids such as tartaric acid, gluconic acid or glucoheptonic acid, and alcohols such as tartaric acid, mannitol, 2
．． 3-butanediol and 1,2.3-propanetriol. The oxyacid used when forming the ester is generally an inorganic acid, such as boric acid, tungstic acid, molybdic acid or chromic acid.

Typically, such ester-forming complexes are in the form of polyesters, which are ester complexes formed by the reaction of two or more moles of an oxyacid with one mole of a polyhydric compound.

Examples of phosphonate complexing agents are aminotri(methylenephosphonic acid) and its salts, such as the pentasodium salt of aminotri(methylenephosphonate), 1-hydroxy/ethylidene-1,1-diphosphonic acid and its salts, such as 1- Trisodium salt of hydroxyethylidene-1,1-diphosphonic acid.

Ethylenediaminetetra (methylphosphonic acid) and its salts, and 1,6-diamithexanetetra (methylphosphonic acid) and its alkali metal and alkaline earth metal salts.

The concentration of complexing agent will, of course, depend somewhat on the particular complexing agent included in the bath. Generally, the complexing agent in the bath is at least about 0.0005 mol/l and 1. Although it can be higher due to bath solubility limitations and economic considerations, it is usually less than about 1.5 mol/l. A typical range is around 0
．． 0.05 to about 1 mol/l, especially when the complexing agent is a carboxylic acid, preferably about 0.1 to 0.7 mol/l. These baths optionally contain stabilizers, e.g. type, antimony or lead sources to adjust the content of sulfur ions, or sulfur-containing compounds, e.g.
Thiourea or a combination thereof, such as thiodiglycolic acid, can be included. Whenever a sulfur-containing compound is added, the sulfur content must be carefully controlled as excessive sulfur will reduce the boron content of the precipitate. Any such sulfur addition should be monitored so that the maximum sulfur concentration is about 20 ppm as divalent sulfur. Otherwise, when adding the stabilizer to the bath, the stabilizer will be at a concentration typical for the particular compound.

Examples of other compositions that can be included in this system at typical bath concentrations are buffers, buffer systems, co-deposition enhancers, and pH adjusting agents, such as strong bases. Borealoy deposits are complexes that are ester complexes produced by reacting a bath-soluble compound, such as a polyhydric acid or alcohol, with the oxyacid of the metal to be deposited as part of a polyalloy with nickel and other metals. This can be achieved by including a curing agent.

When carrying out the process according to the invention, a nickel-boron co-precipitate with a high boron content is produced with a moderate pF containing a source of zirconyl ions and/or vanadyl ions.
(and is formed by precipitation from a boron-reducing electroless nickel bath with a moderate temperature. The operating pH is less than 13, typically 4-10, and proceeds under moderate conditions, while at the same time To take full advantage of the ability of this process to form still high boron precipitates, the pH of the bath is preferably maintained at about 5-7, while the temperature is below 90°C, typically maintained at about 60 to about 70° C. By this method, nickel from the nickel source in the bath is co-precipitated with boron from the reducing agent, and this co-precipitate is equal to or less than 2N, based on the total weight of the precipitate. Contains more than % boron.

The method combines a bath-soluble nickel source, a bath-soluble borane reducing agent, a boron precipitation enhancer that liberates vanadyl ions and H/M or zirconyl ions when added to the bath, preferably with an electroless bath complexing agent. and preparing an electroless deposition bath containing the following: Preparation of the bath can optionally include adding one or more stabilizers, sulfur ion content regulators, buffers, buffer systems, polyalloy precipitation sources, co-precipitation enhancers, and the like. Typically, the bath p
) (to within the desired moderate pH range, this is usually done by adding a strong base, e.g. hydroxide,
Alternatively, when the pH is too high, by adding a strong acid, for example sulfuric acid or other mineral acids, the support to be immersed is immersed in a bath thus prepared. The weight or thickness of the nickel-boron co-deposit formed by this bath will, of course, vary with the plating rate and the immersion time of the support in the bath. The plating speed by this method is about 0.2 to about 0.5 microA (about 0.005
1 to about 0.0127 mm')/Vj tar'), and a typical bath load is about 0.25 to 1.0 square feet/Vj tar').
bath gallon (approximately 0.006-0.025 m/bath l).

Articles made in accordance with the present invention include both metallic and non-metallic supports, said supports being plated with a protective coating of an electroless nickel-boron co-deposit having a boron content of at least about 2% by weight. and said precipitate is formed by the bath according to the invention. These products are
It can have a boron content as high as 5% by weight or higher, based on the weight of the precipitate. usually,
The remainder of the precipitate will be nickel. Such co-precipitates exhibit increased hardness of the order of 800-1 ooo VHN5o.

The following examples further illustrate the invention.

Example l 096 mol/l lactic acid, 0.08 mol/l citric acid,
0.04 mol/l! of dimethylamine borane, 0.01
Mol/l silconyl chloride hydrate, 0.01 mol/l
An electroless bath was prepared containing sufficient ammonium hydroxide to maintain nickel and II) HO,6'.

The bath was heated to 65° C. and the support was immersed therein, when a precipitate of 4.1% by weight boron and 95.5% by weight nickel formed.

Example ■ Another electroless nickel bath was prepared by adding the following ingredients to an aqueous bath: o, 3 mol/l lactic acid, 0.08
mol/l lactic acid, 0.08 mol/l citric acid, 0.0
4 mol/l dimethylamine borane, o, oo 1 mol/l
l of 4a (Vi, vanadyl, 0.01 mol/l nickel and - ammonium hydroxide at a concentration to bring the pH of the bath to 6.0 at 70°C. 6.6% by weight boron and 96.41 % of nickel was formed.

Written amendment to the proceedings Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 146751 of 1982, Title of the invention: Adjustment of boron content in electroless nickel-boron precipitate6,
Relationship with the case of the person making the amendment Address and name of the patent applicant Richardson Chemical Company 4,
Agent 5, [Claims] and [Detailed Description of the Invention] columns of the specification subject to amendment (attachment) (1) The statement in [Claims] will be corrected as follows.

Fl, an electroless nickel bath comprising: a bath-soluble nickel source, a bath-soluble borane reducing agent, and a bath-soluble boron precipitation-enhancing compound, the boron precipitation-enhancing compound being a group consisting of zirconyl ions, vanadyl ions, and combinations thereof. An electroless nickel bath for forming a nickel-boron deposit with a relatively high percentage of boron, characterized in that the ion source is a selected ion source.

2. The electroless bath according to claim 1, wherein the boron precipitation enhancing compound is a zirconyl salt or a vanadyl salt.

3. The electroless bath of claim 1, wherein the boron precipitation enhancing compound is selected from the group consisting of zirconyl chloride, vanadyl sulfate, sodium metavanadate, and combinations thereof.

4. The electroless bath of claim 1, wherein said boron precipitation enhancing compound is included in the bath at a concentration of at least about 0.0005 moles/p based on total bath volume.

5. The electroless bath according to claim 1, wherein the reducing agent is an amine borane or a cyclic amine borane.

6. The electroless bath of claim 1, wherein the borane reducing agent is included in the bath at a concentration of at least about 0,000 moles/min based on the total bath volume.

7. The electroless bath of claim 1, wherein said bath further comprises a complexing agent at a concentration of at least about 0.0005 mole/min based on total bath volume.

8. The electroless bath according to claim 1, further comprising a complexing agent, wherein the complexing agent is a carboxylic acid or a bath-soluble derivative thereof.

9. The electroless bath according to claim 1, further comprising a complexing agent, the complexing agent being a hydroxy-substituted carboxylic acid.

1o, further comprising a complexing agent, the complexing agent being oxyff
The electroless bath according to claim 1, which is an ester complex of fff1 with alcohol.

11. The electroless bath according to claim 1, further comprising a complexing agent, the complexing agent being an organic phosphoric acid complexing agent.

12. Claim 1, wherein the bath further comprises a stabilizer.
Electroless bath as described in section.

13. Claim 1, wherein the bath further comprises a buffering agent.
Electroless bath as described in section.

14. The electroless bath according to claim 1, wherein the bath further comprises a co-deposition enhancer.

”5. 2. The electroless bath according to claim 1, wherein said bath has a temperature of 90 r or less.

]6. An electroless bath according to claim 1, wherein said bath has a pH of less than 1.6.

7. The electroless bath of claim 1, wherein said bath has a p) of from about 5 to about 7.

18. immersing the support in an electroless nickel bath and depositing a nickel-boron deposit thereon, the bath comprising: a bath-soluble nickel source, a bath-soluble borane reducing agent, and a bath-soluble boron deposit. an enhancing compound, characterized in that the boron precipitation enhancing compound is an ion source selected from the group consisting of a combination of zirconyl ions, vanadyl ions, and Oyohiso ions;
A method for increasing the boron content of niranal-boron electroless deposition.

19. The method according to claim 18, wherein the bath is maintained at a humidity of 90 tZ' or less.

20. The method of claim 18, wherein the bath is maintained at a pH of less than 13.

21. The method of claim 18, wherein said bath is maintained at a pH of about 4 to about 10.

22. The method of claim 18, wherein said bath is maintained at a pH of about 5 to about 7.

23. 19. The method of claim 18, wherein the bath further comprises a bath-soluble complexing agent.

24. The precipitation step is based on the total weight of precipitates,
19. The method of claim 18, forming a precipitate containing at least about 2% by weight boron.

25j support and an electroless deposit on the support,
the precipitate has a relatively high percentage of boron, the precipitate is formed by an electroless bath, the bath consisting of: a bath-soluble nickel source, a bath-soluble borane reducing agent, and a bath-soluble boron precipitation enhancement compound; An electroless plating product, wherein the boron precipitation enhancing compound is an ion source selected from the group consisting of zirconyl ions, vanadyl ions, and combinations thereof.

26. The article of claim 25, wherein the percentage of boron is at least about 2% by weight, based on the total weight of the deposit.

27. The article of claim 25, wherein the percentage of boron is as high as about 5% by weight, based on the total weight of the deposit.

28. The article of claim 25, wherein the bath further comprises a bath-soluble complexing agent.

29. The product of claim 25, wherein the bath is maintained at a temperature of less than 900 and a pH of less than 16.

3o. present on a support and formed by immersing the support into an electroless bath, said bath comprising: a bath-soluble nickel source, a bath-soluble borane reducing agent, and a bath-soluble boron precipitation enhancement compound; An electroless nickel-boron deposit, wherein the precipitation enhancing compound is an ion source selected from the group consisting of zirconyl ions, vanadyl ions, and combinations thereof.

Claims (1)

[Scope of Claims] 1. The electroless nickel bath comprises: a bath-soluble nickel source, a bath-soluble boron reducing agent, and a bath-soluble boron precipitation enhancement compound, and the boron precipitation enhancement compound includes zirconyl ions, vanadyl ions, and An electroless nickel bath for forming a nickel-boron deposit with a relatively high percentage of boron, characterized in that the ion source is selected from the group consisting of combinations thereof. 2. The electroless bath according to claim 1, wherein the boron precipitation enhancing compound is a zirconyl salt or a vanadyl salt. 3. The boron precipitation enhancing compound is zirconyl chloride, vanadyl sulfate, and sodium metavanadate. and a combination thereof. 4. The boron precipitation enhancing compound has a total bath volume of -
based on at least about [1,(J 005 mol/l
concentration of . An electroless bath according to claim 1, which is contained in the bath. 5. The electroless bath according to claim 1, wherein the reducing agent is an amine borane or a cyclic amine borane. 6. The electroless bath of claim 1, wherein the borane reducing agent is included in the bath at a concentration of at least about o, ooi moles/l, based on the total bath volume. 7. The electroless bath of claim 1, wherein said bath further comprises a complexing agent at a concentration of at least about 0.0005 mol/l, based on the total bath volume. 8. The electroless bath according to claim 1, further comprising a complexing agent, wherein the complexing agent is a carboxylic acid or a bath-soluble derivative thereof. 9. The electroless bath according to claim 1, further comprising a complexing agent, the complexing agent being a hydroxy-7-substituted carboxylic acid. 10. 2. The electroless bath according to claim 1, further comprising a complexing agent, wherein the complexing agent is an ester complex of an oxyacid and a polyhydric acid or alcohol. 11. The electroless bath according to claim 1, further comprising a complexing agent, the complexing agent being an organic phosphoric acid complexing agent. 12. Claim 1, wherein the bath further comprises a stabilizer.
Electroless bath as described in section. 13. Claim 1, wherein the bath further comprises a buffering agent.
Electroless bath as described in section. 14. The electroless bath according to claim 1, wherein the bath further comprises a co-deposition enhancer. 15. The electroless bath according to claim 1, wherein the bath has a temperature of 90°C or less. 16. The electroless bath of claim 1, wherein said bath has a pH of less than 16. 17. The electroless bath of claim 1, wherein the bath has a pl of about 5 to about 7 pl. a bath-soluble nickel source, a bath-soluble boron reducing agent, and a bath-soluble boron precipitation enhancement compound, wherein the boron precipitation enhancement compound includes zirconyl ions, vanadyl ions, and combinations thereof. an ion source selected from the group consisting of;
A method for increasing the boron content of nickel-boron electroless deposition. 19. The method of claim 18, wherein the bath is maintained at a temperature of 90°C or less. 20. The method of claim 18, wherein said bath has a pHVCja of less than 13. 21. The method of claim 18, wherein said bath is maintained at a pH of about 4 to about 10. 22. The method of claim 18, wherein said bath is maintained at a pH of about 5 to about 7. 23. The method of claim 18, wherein the bath further comprises a bath-soluble complexing agent. 24. The method of claim 18, wherein the AiJ precipitation step forms a precipitate containing at least about 2% by weight boron, based on the total weight of the precipitate. 25 comprising a support and an electroless deposit on said support, said deposit having a relatively high percentage of boron, said deposit being formed by an electroless bath, said bath comprising: a bath-soluble nickel source; , a bath-soluble boron reducing agent, and a bath-soluble boron precipitation enhancing compound, wherein the boron precipitation enhancing compound is an ion source selected from the group consisting of zirconyl ions, vanadyl ions, and combinations thereof. Electroless plating products. 26. Claim 2, wherein the percentage of boron is at least about 2% by weight, based on the total weight of the precipitate.
Products listed in Section 5. 27. The article of claim 25, wherein the percentage of boron is as high as about 5% by weight, based on the total weight of the deposit. 28. The article of claim 25, wherein the bath further comprises a bath-soluble complexing agent. 29. The product of claim 25, wherein the bath is maintained at a temperature of less than 90°C and a pH of less than 16. 30, present on the support and formed by immersing the support into an electroless bath, the bath comprising: a bath-soluble nickel source, a bath-soluble boron reducing agent, and a bath-soluble boron precipitation enhancement compound; An electroless nickel-boron deposit, wherein the boron precipitation enhancing compound is an ion source selected from the group consisting of zirconyl ions, vanadyl ions, and combinations thereof. 31. The electroless nickel-boron deposit of claim 30, wherein said deposit has a percentage of boron that is at least about 2% by weight, based on the total weight of the deposit. 32. The electroless nickel-boron precipitate according to claim 61, wherein the percentage of boron is as high as 5% by weight, based on the total amount of N in the precipitate. 61. The electroless nickel-boron deposit of claim 60, further comprising an agent. 34. The electroless nickel deposit of claim 30, wherein said bath is maintained at a temperature of less than 90<0>C and a pH of from about 4 to about 10.