JPH083753A - Electroless ni plating solution for aln substrate - Google Patents

Abstract

PURPOSE:To selectively and more rapidly form the thin film of an Ni-contg. plating excellent in adhesion, hardness, etc., by conducting electroless plating on a wiring without bleeding even if the fine wiring is formed on an AlN substrate without corrosing the substrate. CONSTITUTION:The electroless plating soln. for an AlN substrate contains (water of crystallization-contg.) nickel sulfate, (water of crystallization-contg.) nickel chloride or (water of crystallization-contg.) nickel acetate as an Ni ion source, (water of crystallization-contg.) ethylene-dimamine as a complexing agent, (water of crystallization-contg.) sodium hypophosphite as a reducing agent, at least one kind among lactic acid, sodium succinate and sodium acetate as the org. acid or org. acid salt and further d-thiourea and/or thallium malonate. Consequently, when the plating soln. is used, the yield in plating is greatly improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to electroless Ni for AlN substrates.
More specifically, the present invention relates to an electroless Ni-based plating solution for AlN substrates, which is useful, for example, when Ni-plating an AlN substrate in a manufacturing process of an IC package or the like.

[0002]

2. Description of the Related Art In contrast to electroplating in which an electric current is applied from the outside to reduce and deposit metal ions in a solution on a cathode, metal ions in a solution are reduced and deposited on the surface of an object to be plated without using an external current. The method is generally called chemical plating. The chemical plating is roughly classified into immersion plating based on ion substitution and electroless plating using a chemical reducing agent.

In the immersion plating, a metal such as Ni is immersed in a solution containing ions of a noble metal such as gold,
This is a method of depositing gold on Ni by a so-called substitution reaction, and once the Ni surface is covered with gold, the growth of plating also stops, so there is a problem that thick plating is difficult.

On the other hand, in the electroless plating, a salt of a metal to be deposited in a solution, a complexing agent for forming a complex with the metal, a reducing agent for reducing a metal complex to reduce and deposit a simple metal, a solution. The material to be plated is mixed in a solution in which a pH buffering agent for suppressing fluctuations in the pH, a pH adjusting agent for keeping the pH value constant, and a stabilizing agent for stabilizing the solution are mixed. It is a method of dipping and reducing and depositing a metal on the surface of the object to be plated.

A problem with this method is that the metal is reduced and deposited by a reducing agent instead of an electric current, so that the cost is higher than that of electrolytic plating, and when an attempt is made to increase the plating speed, a powder state in the plating bath is used. There is a possibility that the metal may be deposited, so that the plating speed cannot be increased too much.

[0006] On the other hand, on the other hand, a power source, electrodes, etc. are not required, and by simply immersing the object to be plated in a plating solution, it is possible to obtain a coating having a uniform thickness excellent in adhesion, homogeneity, etc. It is easy to control the properties of the sheath by changing the plating conditions such as the composition of the plating solution, and it is possible to form a coating that meets the required characteristics. It is widely used industrially because of its excellent features such as that it is possible to perform direct plating on non-conductive substances such as plastic, glass, ceramics and the like.

[0007] When the electroless plating treatment is applied to the object to be plated, the mechanism of what reaction proceeds in the solution to form the plating film is not completely understood. Absent.

However, for example, when hypophosphite is used as the reducing agent and electroless Ni plating treatment is applied to a ceramic substrate or the like, the chemical reaction shown in the following chemical formulas 1 to 3 is performed in the solution. It is said to proceed.

[0009]

[Formula 1] _{^{Ni 2+ + H 2 PO 2+ H}} 2 O → Ni + H 2
PO ₃ ^{- +} 2H +

[0010]

Embedded image H ₂ PO ₂ ⁻ + H ₂ O → H ₂ PO ₃ ⁻ + H ₂

[0011]

Embedded image H ₂ PO ₂ ⁻ + H → P + H ₂ O + OH ⁻ As shown in the above formula 1, oxidation of phosphorus in hypophosphite ions progresses, Ni is reduced, and the surface of the object to be plated is reduced. To deposit. At this time, the reaction of Chemical formula 2 also proceeds at the same time, water is reduced and hydrogen is generated. Hydrogen is actually involved in the reductive precipitation of Ni shown in Chemical formula 1, and Ni is reduced by transferring electrons to the Ni ions by the hydrogen atom once reduced in the reaction of Chemical formula 2 above. It is said to be. Further, with respect to hypophosphorous acid, a disproportionation reaction progresses, and a part of phosphorus is oxidized as shown in Chemical formula 2, and at the same time, a part of other phosphorus is changed as shown in Chemical formula 3. It is reduced and phosphorus is deposited. That is, the hydrogen atom once reduced by the reaction of Chemical formula 2 releases an electron also to the phosphorus in the hypophosphite ion, whereby the phosphorus in the hypophosphite ion is also reduced. Therefore, the deposited film usually becomes an alloy of Ni and phosphorus. This Ni alloy has characteristics that it is more excellent in hardness of the coating, adhesion to the substrate, and the like, as compared with a coating of Ni alone.

In electroless Ni plating, it is considered that the deposition reaction of the plated coating proceeds due to the above-mentioned reaction, but this deposition reaction forms a coating having excellent wear resistance and heat resistance, so that it is industrially used. It has been used for a long time and has been studied for a long time, and its reaction mechanism is gradually becoming clear.

[0013]

Thus, although electroless plating is widely used, this electroless N
The objects to be plated that were subjected to i-plating processing were limited. That is, the object to be plated is relatively stable to acids and bases such as Al ₂ O ₃ plate, Cu plate, and Au plate, and corrodes the substrate even when immersed in a high temperature solution for a long time. Most of them do not occur. Therefore, in the past, 90 to 1 has been used for the above-mentioned object to be plated.
It was possible to perform the plating treatment in a high temperature range of about 00 ° C.

In recent years, it has come to be used for plating of printed wiring boards and the like, and in this case, it is desirable that the temperature for forming the coating is low, so that 3
A low-temperature Ni-based plating solution that can be plated at a low temperature of 0 to 60 ° C. has also been developed. However, these Ni-based plating solutions are also intended for the object to be plated having a relatively high corrosion resistance, and are not intended for chemically unstable substrates such as AlN substrates. Table 1 below shows the composition of the Ni-based plating solution that is conventionally used for plating in the high temperature range, and Ni that is used for plating in the low temperature range.
The composition of the system plating solution is shown in Table 2 below.

[0015]

[Table 1]

[0016]

[Table 2]

Let us perform electroless plating on the wiring formed by co-firing with Cu or W paste or on the AlN substrate having the wiring formed by a method such as the sputtering method on the surface. If any of the conventionally used Ni-based plating solutions shown in Tables 1 and 2 above is used, a bleed phenomenon occurs in which a plating film is formed in a place other than the metal wiring portion. Or
The AlN substrate itself was dissolved, or an autolysis reaction of the solution occurred. When the self-decomposition reaction occurs, Ni in the form of powder or Ni in the form of foil will be reduced and precipitated in the solution, and thus the precipitated powder will adhere to the substrate,
The Ni concentration in the solution changes, and the conditions for forming the film change, resulting in an extremely low plating rate.

As described above, it is difficult to find a condition in which only the metal wiring on the surface of the AlN substrate is plated. Especially, when a metal such as W is contained in the AlN substrate as a coloring agent or the like. It is difficult to prevent the bleeding phenomenon because a plating film is formed on a portion where the metal is exposed and the plating film spreads starting from this portion. In addition, the coloring agent such as W existing in the AlN substrate is usually transmitted through the AlN substrate by ultraviolet rays or the like so that S
It is added in order to prevent the i substrate and the like from being deteriorated.

Therefore, the present inventors have previously described (crystal-containing water) nickel sulfate, (crystal-containing water) nickel chloride or (crystal-containing water) nickel acetate as a Ni ion source, and (crystal-containing water) ethylenediamine as a complexing agent. We proposed an electroless Ni-based plating solution for AlN substrates containing lactic acid as a second complexing agent and sodium hypophosphite (containing water of crystallization) as a reducing agent (Japanese Patent Application No. 5-298590).

The electroless Ni-based plating solution for the AlN substrate described above is used for the Ni-containing plating having excellent characteristics such as film hardness for the wiring formed on the AlN substrate by the electroless plating method without corroding the AlN substrate. It has the excellent property of being able to form a coating selectively and quickly, but it is improved in terms of the plating property for fine wiring, the formation rate of the plated coating, and the suppression of the amount of hydrogen generated during plating. There was room for

[0021]

Therefore, the present inventors have aimed to improve the plating property for fine wiring, increase the formation rate of the plating film, further suppress the amount of hydrogen generated during plating, and improve the plating yield. However, although it was described that the addition to the plating solution had an effect on the stability of the plating solution and an increase in the rate of formation of the plating film, the above-mentioned plating solution (low temperature reduction As a result of the addition of thiourea and thallium malonate, which have never been used for electroless plating, to the plating solution, the inventors have found that the above-mentioned objects can be almost achieved, and have completed the present invention.

That is, the electroless Ni plating solution for an AlN substrate according to the present invention comprises (a) nickel sulfate (containing crystal water), nickel chloride (containing crystal water) or nickel acetate (containing crystal water) as a Ni ion source, ( b) (Crystalline water) as the complexing agent, (d) (Crystalline water) sodium hypophosphite as the reducing agent, (c) Organic acid or organic acid or lactic acid, sodium succinate or sodium acetate It is characterized by containing at least one kind and further containing (d) thiourea and / or thallium malonate.

In the present invention, the concentration of nickel sulfate (containing crystal water), nickel chloride (containing crystal water) or nickel acetate (containing crystal water) used as the Ni ion source in the Ni-based plating solution is 0. About 0.1 to 0.10 mol / liter is preferable. Here, for example, the description that nickel sulfate is (crystal water containing) nickel sulfate means that the nickel sulfate may contain crystal water or may be an anhydride. This also applies to other compounds. In the following, a compound to which (water of crystallization) is added will be represented by omitting (water of crystallization), but in reality, a compound containing water of crystallization is also included.

If the concentration of the nickel sulfate, nickel chloride or nickel acetate in the Ni-based plating solution is less than 0.01 mol / liter, the Ni ion concentration in the Ni-based plating solution decreases, so that the Ni coating film is formed. If the concentration of the nickel sulfate or nickel chloride in the Ni-based plating solution exceeds 0.10 mol / liter, powder or foil pieces in the solution become difficult. -Like Ni tends to precipitate, and the precipitation rate decreases on the contrary.

The concentration of ethylenediamine used as a complexing agent in the Ni-based plating solution is 0.05 to 0.20.
About mol / liter is preferable. N of ethylenediamine
If the concentration in the i-based plating solution is less than 0.05 mol / liter, it cannot form a complex with Ni ²⁺ completely,
On the other hand, when the concentration of ethylenediamine in the Ni-based plating solution exceeds 0.20 mol / liter, the amount of the complexing agent becomes too large.
A stable complex of i is formed and Ni is less likely to precipitate.

The concentration of sodium hypophosphite used as a reducing agent in the Ni-based plating solution is 0.05 to 0.
30 mol / liter is preferred. If the concentration of sodium hypophosphite in the Ni-based plating solution is less than 0.05 mol / liter, the reducing power is weak and Ni is not precipitated, while the sodium hypophosphite is used in the Ni-based plating solution. If the concentration in the medium exceeds 0.30 mol / liter, the oxidation reaction of the hypophosphite ion shown in Chemical formula 1 proceeds, and the amount of free Ni ion also increases. Decrease.

The concentration of lactic acid used as an organic acid in the Ni-based plating solution is preferably about 0.15 to 0.30 mol / liter. When the concentration of lactic acid in the Ni-based plating solution is less than 0.15 mol / liter, the deposition rate of Ni is high, but the pH of the Ni-based plating solution becomes unstable and a plated film is formed at a stable rate. When the concentration of lactic acid in the Ni-based plating solution exceeds 0.30 mol / liter, the amount of the complexing agent becomes too large as a whole, so that the precipitation amount of Ni is suppressed. To be done. This lactic acid serves as a complexing agent and as a pH adjusting agent. Since the lactic acid has a chiral center, there are two types of optical isomers, but in the present invention, either one may be used, or a commercially available racemate may be used.

The concentration of sodium succinate or sodium acetate used as the organic acid in the Ni-based plating solution is preferably about 0.05 to 0.30 mol / liter. When the concentration of the organic acid in the Ni-based plating solution is less than 0.05 mol / liter, the sodium salt of these organic acids does not cause a pH buffering action despite having a function mainly as a pH buffering agent. If the concentration of the organic acid in the Ni-based plating solution exceeds 0.3 mol / liter while violently changing the pH of the plating solution, a stable compound is formed with the Ni salt, resulting in a decrease in the deposition rate. cause.

FIG. 1 shows thiourea or thallium malonate when thiourea or thallium malonate is added to a plating solution containing the Ni ion source, the complexing agent, the reducing agent, the organic acid, and the organic acid salt. 5 is a graph showing the relationship between the addition amount of Ni and the precipitation amount of Ni. As shown in FIG. 1, in the case of thiourea, Ni was added in the range of 0.2 to 0.6 mg / liter.
Most precipitation, 0.2 ~ for thallium malonate
It can be seen that the Ni precipitation amount is the largest in the range of 0.8 mg / liter. The Ni deposition amount is the deposition amount when an NiN coating film is formed by immersing an AlN substrate having a 2500 mm ² metal underlayer formed thereon in a plating solution for 15 minutes.

As described above, the concentration of thiourea in the Ni plating solution is preferably 0.2 to 0.6 mg / liter, and the concentration of thiourea in the Ni plating is 0.2 mg / liter.
If it is less than 1 liter, the amount of Ni deposited is reduced and the amount of hydrogen generated is increased, so that bleeding is likely to occur in the fine wiring portion, while the concentration of thiourea in the Ni-based plating solution is 0.6 mg / liter. Even if it exceeds, the precipitation amount of Ni similarly decreases.

The concentration of thallium malonate in the Ni plating is preferably 0.2 to 0.8 mg / liter, and the concentration of thallium malonate in the Ni-based plating solution is 0.2.
If it is less than mg / liter, the amount of Ni deposited decreases,
On the other hand, even if the concentration of thallium malonate in the Ni-based plating solution exceeds 0.8 mg / liter, the amount of Ni deposited is similarly reduced.

In the electroless Ni plating solution for AlN substrate according to the present invention, the Ni ion source, the complexing agent, the reducing agent, the organic acid, the organic acid salt, thiourea, and thallium malonate are usually used. They are used by mixing in an appropriate combination and the pH is adjusted by adding an acid, but other additives may be added depending on the conditions such as the type of the underlying metal formed on the substrate and the thickness of the plating layer. May be added. Here, the acid used for adjusting the pH is preferably hydrochloric acid. When sulfuric acid or nitric acid is used, SO ₄ ²⁻ ion in sulfuric acid or NO ₃ ⁻ ion in nitric acid adversely affects the stability of the formed Ni complex, which is not preferable. Particularly, in the case of NO ₃ ⁻ ion, Ni (NO ₃ ) ₂ forms a stable salt, which is not preferable. Examples of the additives include organic acid salts that function as pH buffers and organic acids that function as pH adjusters.

Next, a method of plating the AlN substrate using this electroless Ni-based plating solution for the AlN substrate will be described.

FIG. 2 shows that the Ni ion source, the complexing agent, the reducing agent, the organic acid, and thiourea are added at concentrations of 0.4 mg / liter and thallium malonate at concentrations of 0.5 mg / liter. 5 is a graph showing the relationship between the temperature of the plating solution or the pH of the plating solution when added to and mixed with the plating solution containing an organic acid salt and the Ni deposition amount. In both cases, the pH was 6.00 and the temperature was 6 when Ni was deposited.
It is set to 0 ° C.

As shown in FIG. 2, the preferred temperature for adding and mixing thiourea and thallium malonate is 60 to
70 ° C., the preferable pH is 6 to 7, and it is understood that the amount of precipitation decreases if the temperature or pH is out of the range during mixing.

In order to form a uniform film having excellent characteristics, the pH is 6 to 7 and the temperature is 6 during the plating process.
Set the temperature of the Ni-based plating solution within ± 1 ° C and set the pH within ± 1 ° C while setting the temperature to 0 to 80 ° C
It is preferable to keep it within 0.05. In addition, agitate the Ni-based plating solution and rotate the AlN substrate sufficiently to constantly
It is necessary to ensure that the substrate is supplied with fresh solution. Further, it is necessary to remove dissolved oxygen by blowing nitrogen or argon gas into the Ni-based plating solution.

[0037]

According to the electroless Ni plating solution for an AlN substrate according to the present invention, (a) nickel sulfate (containing crystal water), (containing crystal water) nickel chloride or (containing crystal water) is used as the Ni ion source.
Nickel acetate, (b) complexing water (containing water of crystallization) ethylenediamine, (d) reducing agent (containing water of crystallization) sodium hypophosphite, (c) lactic acid as an organic acid or organic acid salt,
It contains at least one of sodium succinate and sodium acetate, and further contains (d) thiourea and / or thallium malonate, and by the electroless plating method, the AlN substrate is not corroded and fine Even if a fine wiring is formed, N which has excellent characteristics such as film adhesion and hardness to the wiring without causing bleeding.
The i-containing plating film is formed selectively and more quickly.

[0038]

EXAMPLES AND COMPARATIVE EXAMPLES Hereinafter, the case where the AlN substrate is subjected to the electroless Ni plating treatment using the electroless Ni plating solution for the AlN substrate according to the present invention will be described. As a comparative example, a case where a plating film is formed by using an electroless Ni-based plating solution having a composition different from that of the electroless Ni-based plating solution according to the present invention will be described.

As the AlN substrate, A manufactured by Sumitomo Metal Ceramics Co., Ltd., which has calcium aluminum oxide, calcium yttrium aluminum oxide or the like at grain boundaries, is used.
An IN substrate was used. Then, on the AlN substrate, Ti, Mo, and Cu coatings are sequentially formed by sputtering so as to have predetermined wiring patterns and pad patterns.
It was formed to a thickness of 05 μm, 0.5 μm, and 0.5 μm to form a base metal layer for forming a plating film. The minimum line width of this wiring was 30 μm, the distance between the lines was 20 μm, and the total area thereof was 2500 mm ² .

On the base metal layer, the following Table 3 and Table 4 are given.
The plating film was formed using the electroless Ni-based plating solution having the composition shown in Fig. 1, but first, nickel chloride hexahydrate (NiCl 2) was used as the basic component (Ni ion source, complexing agent, reducing agent). ₂ · 6H ₂ O), sodium hypophosphite monohydrate _{(NaH 2 PO 2 · H 2} O), using ethylenediamine (en), and adjusted to a concentration shown in Table 3 and Table 4 below. This concentration is from N-Rochelle salt complex to N
A value that maximizes the amount of film deposition when i is chemically reduced is selected.

Regarding the organic acid and the organic acid salt, those shown in Table 3 and Table 4 were used, and the concentrations were 0.16 mol / l of lactic acid and 0.01 mol / l of EDTA.2Na, and the organic acid salt was All were 0.08 mol / liter.
The reason for setting this concentration is that the appropriate concentration of the pH buffer in the Ni-Rochelle salt complex solution is 0.07 each.
Since the amount was 5 mol / liter, the reason for this is to adjust the concentration to be almost the same and compare the effects. Furthermore, in this example, the concentration of thiourea was 0.4 mg / liter,
The concentration of thallium malonate was 0.5 mg / liter. This added amount is selected from the relationship between the added amount of thiourea and thallium malonate and the Ni deposition amount shown in FIG.

The Ni-based plating solutions according to the examples and comparative examples were prepared as follows. First, each of the basic components was added to a 500 ml beaker. Addition amount is 1 in total
The amount is such that the concentration becomes that shown in Tables 3 and 4 when it is made to be liter. Stir these ingredients well and mix,
The pH was adjusted with dilute hydrochloric acid so as to be in the range of 6.4 to 6.6. After that, the organic acid, organic acid salt, thiourea, and thallium malonate shown in Tables 3 and 4 were added so as to have a set concentration, and after measuring up to a 1-liter measuring flask, a predetermined pH described later was obtained. Adjusted to. This is to make up after preparing all the reagents at once,
This is because if the pH is adjusted, a strong buffer action acts on the solution, making it difficult to adjust the pH, which may change the liquidity of the plating solution.

An AlN substrate having a metal thin film obtained by the above method was dipped in this Ni-based plating solution to perform plating treatment. At this time, the temperature of the Ni-based plating solution is set to 60.
The pH was kept within ± 1 ° C. and pH within 6.00 ± 0.01, and the Ni-based plating solution was agitated and the AlN substrate was rotated sufficiently so that a fresh solution was always supplied to the AlN substrate. . During the plating treatment, nitrogen was blown into the Ni-based plating solution to remove dissolved oxygen. The plating treatment time was 15 minutes.

Next, the AlN substrate on which the plating film was formed by the plating treatment was mixed with 25 ml of concentrated nitric acid (special grade reagent manufactured by Kishida Chemical Co., Ltd.) and concentrated sulfuric acid (special grade reagent manufactured by Kishida Chemical Co., Ltd.). (Reagent) 25 ml and then diluted with pure water to make a 100 ml solution to dissolve the plating film. Then, the metal ion concentration in the solution in which the plating film is dissolved is determined by ICP (Inductively Coupled).
Plasma) The concentration of dissolved Ni ions and P ions was determined by emission spectroscopic analysis, and the amount of Ni deposited and the content of P were determined.

By dipping this AlN substrate in a mixed acid solution, Mo, Cu, etc. of the underlying metal layer and the AlN substrate itself were corroded and dissolved, but this did not particularly affect the quantitative analysis of Ni ions and P ions. . The results are shown in Tables 3 and 4 below.

[0046]

[Table 3]

[0047]

[Table 4]

In Tables 3 and 4 above, P ions were detected in the solution in which the plated coating was dissolved. The reason why sodium hypophosphite was deposited at the same time when the Ni plated coating was formed was This is because it forms an alloy with.

As can be seen from Tables 3 and 4, the electroless Ni-based plating solution for the AlN substrate according to the example in which the organic acid and the organic acid salt are added to the basic components, and thiourea or thallium malonate is further added. In comparison, the amount of Ni deposited was larger than that of the plating solution according to the comparative example to which the above compound was not added, and the amount of precipitation was particularly large when both thiourea and thallium malonate were added. In addition, the amount of Ni deposited increases in the system in which sodium succinate and sodium acetate are added as organic acid salts. From this result, the composition obtained by adding lactic acid, sodium succinate, or sodium acetate as an organic acid or an organic acid salt to the three types of basic components according to the example, and further adding thiourea and thallium malonate as a basic composition It can be seen that the electroless Ni-based plating solution that has a large amount of deposition has excellent properties as a Ni-based plating solution. Further, even in the fine wiring portion, the bilead phenomenon was not observed at all, and the plating film was formed only on the wiring portion.

Next, using an alumina substrate on the surface of which copper was printed in an area of 2500 mm ² , the above Tables 3 and 4 were used.
Electroless N for AlN substrates according to the examples and comparative examples shown in FIG.
With respect to a plating solution having the same composition as some of the i plating solutions, the amount of hydrogen generated during the plating treatment was measured. As another comparative example, a commercially available plating solution was used and the amount of hydrogen generated was measured in the same manner.

The amount of hydrogen generated was measured by the method described below. That is, a through hole through which a tube is inserted is formed in a part of the through hole, and a flat plate-shaped lid in which a tube is inserted into the through hole is produced. The flat plate-shaped lid is placed in a container containing a plating solution. The container was sealed so that gas would not leak from anywhere other than the tube. Next, put a graduated cylinder whose inside is filled with water in a water tank and turn it upside down,
The tip of the tube was put inside the graduated cylinder, and hydrogen gas generated by the plating reaction was collected inside the graduated cylinder to measure its capacity.

As the commercially available plating solution, Linden SA manufactured by World Metal Co., Ltd. was used for Comparative Examples 13 to 16, and Top Nicolon U manufactured by Okuno Chemical Industries, Ltd. was used for Comparative Examples 17 to 20. In the case of 13 and 17, the commercially available plating solution was used as it is, in the case of Comparative Examples 14 and 18, thiourea was added to the commercially available plating solution at 0.4 mg / liter, and in the case of Comparative Examples 15 and 19, the commercially available plating solution was used. Comparative Example 1 by adding thallium malonate to the plating solution of 0.5 mg / liter
In the case of 6 and 20, thiourea was added to the commercially available plating solution in an amount of 0.
4 mg / liter and 0.5 mg thallium malonate
/ Liter was added and used as a plating solution. The method of use was as specified by the manufacturer.
In the other examples and comparative examples, the plating solutions under the same conditions as those of the examples and comparative examples shown in Tables 3 and 4 are used.

An attempt was made to analyze the composition of the commercially available product, but it was not clear. However, it is clearly different from the electroless Ni plating solutions for AlN substrates according to the examples, and it is only known that Rochelle salt is used as a complexing agent.

[0054]

[Table 5]

As is clear from the results shown in Table 5, the hydrogen generation amount of the commercially available product was almost the same as that of the plating liquid without addition, regardless of which additive was added.
Although the effect of suppressing the amount of generated hydrogen was not observed, the amount of generated hydrogen was greatly reduced and the amount of Ni deposited was also increased in the electroless Ni plating solutions for AlN substrates according to the examples. Since the generation of hydrogen is suppressed by using the electroless Ni plating solution for an AlN substrate according to the embodiment as described above, the film adhesion of the plating film by the hydrogen generated between the plating film and the underlying metal layer is suppressed. Is never reduced.

In addition, Example 3, Comparative Examples 3, 13, 16,
A plating solution having the same composition as in the cases of 17 and 20 was used to form a plating film on the AlN substrate used in carrying out the examples and comparative examples shown in Tables 3 and 4 above.
The yield was measured. The number of times the plating film is formed is
12 times each. A good product was one in which the bleeding phenomenon did not occur at all on the fine wiring of the plated AlN substrate and the plating film was formed on the wiring portion to a thickness of about 4 μm or more.

As a result, in the case of Example 3, the yield was 98%.
And a very large value, whereas in Comparative Example 3, it was 88.
%, 80% in Comparative Example 16, 85% in Comparative Example 16, 80% in Comparative Example 17, and 85% in Comparative Example 20. As described above, the yield is improved by adding thiourea and thallium malonate to the commercially available plating solution, but the yield is considerably smaller than that of the electroless Ni plating solution for AlN substrate according to the example. all right.

[0058]

As described above in detail, the AlN according to the present invention is
In the electroless Ni plating solution for substrates, (a) nickel sulfate (containing crystal water), nickel chloride (containing crystal water) or nickel acetate (containing crystal water) as a Ni ion source, and (b) as a complexing agent (Crystalline water) Ethylenediamine, (d) Reducing agent (Crystalline water) sodium hypophosphite, (c) Organic acid or organic acid salt as at least one of lactic acid, sodium succinate and sodium acetate. (D) It contains thiourea and / or thallium malonate and causes bleeding by an electroless plating method without corroding the AlN substrate and even when fine wiring is formed on the AlN substrate. The Ni-containing plating film having excellent properties such as film adhesion and hardness can be selectively and more quickly formed on the wiring. for that reason,
When the Ni-based plating solution is used, the yield during the plating process can be greatly improved.

[Brief description of drawings]

FIG. 1 is an amount of thiourea or thallium malonate added and Ni deposition when thiourea or thallium malonate is added to a plating solution containing a Ni ion source, a complexing agent, a reducing agent, an organic acid, and an organic acid salt. It is the graph which showed the relationship with quantity.

FIG. 2: Thiourea and thallium malonate in prescribed amounts, N
The relationship between the temperature of the plating solution or the pH of the plating solution when added to and mixed with the plating solution containing the i-ion source, the complexing agent, the reducing agent, the organic acid, and the organic acid salt and the Ni deposition amount was shown. It is a graph.

Claims (1)

[Claims] 1. (a) As a Ni ion source (crystal water)
Nickel sulfate, (crystal-containing water) nickel chloride or (crystal-containing water) nickel acetate, (b) complexing water (crystal-containing water) ethylenediamine, (d) reducing agent (crystal-containing water) sodium hypophosphite, (C) At least one of lactic acid, sodium succinate, and sodium acetate as an organic acid or organic acid salt, and (d) thiourea and / or thallium malonate, which are not used for AlN substrates. Electrolytic Ni-based plating solution.