JP2006002217A - Method of pretreatment to electroless plating and electroless plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of pretreatment to electroless plating where the precipitation of electroless plating to the region other than a conductor pattern can be sufficiently suppressed, and further, the conductor pattern can be sufficiently covered by an electroless plating film. <P>SOLUTION: The method of pretreatment to electroless plating comprises: a first stage wherein a solution containing a nonionic surfactant is brought into contact with a conductor pattern with a prescribed shape formed on the surface of a substrate; and a second stage wherein a solution containing a cationic surfactant is brought into contact with the conductor pattern after the first stage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pretreatment method for electroless plating and an electroless plating method.

  Conventionally, as a method for selectively forming a plating film such as nickel only on a conductor pattern made of, for example, silver or copper formed on a printed wiring board, an electrolytic plating method and an electroless plating method are widely known. . Among these, the electrolytic plating method is mainly adopted because it is advantageous from the viewpoint of processing cost and bath stability.

  On the other hand, in recent years, there has been a need for higher integration and / or microminiaturization of the mounting of electronic circuits on wiring boards such as semiconductor devices. However, the above-described electrolytic plating method has design restrictions on the power supply leads, and it is relatively difficult to form a plating film on the isolated pattern, so there are cases where such a requirement cannot be met. . Therefore, it is expected that the need for an electroless plating method that is advantageous in this respect will increase in the future.

  Conventionally, nickel plating by the electroless plating method is generally performed through the following steps. First, a printed wiring board on which a conductive pattern made of metal is formed is degreased, and then washed with an acid, and then, for example, a palladium-based catalyst serving as the core of electroless plating is adsorbed. Thereafter, the wiring board is immersed in an electroless nickel plating solution, and the conductor pattern is covered with a desired nickel plating film. When gold plating is further formed on nickel plating, the wiring board is immersed in a replacement gold plating solution to obtain a printed wiring board in which the conductor pattern is coated with a desired gold plating film. In addition, since a running water washing process for several minutes is usually performed between each process, the liquid used in the previous process is less likely to be mixed into the liquid used in the subsequent process, thereby causing a short circuit between the conductor patterns. A selective plating process that is sufficiently suppressed is possible.

  However, when the interval between the conductor patterns becomes as narrow as about 80 to 100 μm, the deposition of the plating on the region other than the conductor pattern becomes relatively remarkable, and thus the occurrence of short circuit between the conductor patterns tends to increase. . In order to prevent such a short circuit, for example, Patent Document 1 discloses a method for improving the palladium catalyst solution to reduce the amount of adsorption of the palladium catalyst on the conductor pattern.

That is, Patent Document 1 intends to suppress palladium adsorption on an insulator, to suppress protrusion of nickel from a line to 1 μm or less, and to significantly improve the electrical reliability of a fine pattern. Treatment with a palladium catalyst solution for electroless nickel plating obtained by dissolving and reacting ammonia and ammonia compound in a buffer solution of pH 3.0 to 4.5 composed of hydrochloric acid and citrate, washing with water, and electroless nickel plating treatment An electroless nickel plating method has been proposed.
JP-A-5-156457

  Recently, a finer conductor pattern, for example, a conductor pattern in which an interval between patterns is less than 80 μm is being put into practical use. The inventors of the present invention have studied in detail the conventional electroless nickel plating method described in Patent Document 1 described above, and using such a conventional electroless nickel plating method, on such an ultrafine conductor pattern. It has been found that when an electroless nickel plating film is formed, a short circuit between conductor patterns cannot be sufficiently suppressed due to the deposition of nickel plating in a region other than the conductor pattern. Furthermore, the present inventors have found that if the amount of adsorption of the palladium-based catalyst is reduced in order to suppress the deposition of nickel plating in a region other than the conductor pattern, the conductor pattern cannot be sufficiently covered with electroless nickel plating. It was.

  Therefore, the present invention has been made in view of the above circumstances, and can sufficiently prevent the deposition of electroless plating on regions other than the conductor pattern and can sufficiently cover the conductor pattern with the electroless plating film. An object of the present invention is to provide an electroless plating pretreatment method and an electroless plating method.

  As a result of intensive studies to achieve the above object, the present inventors have found that the degreasing treatment of the conductor pattern affects the selective formation of the electroless plating film on the conductor pattern. As a result of further research, adjusting the type of degreasing liquid used for the degreasing treatment is insufficient for selective formation of the plating film on the conductor pattern, and multiple types of degreasing liquids are used. It was found that it was necessary to adjust the order of using the degreasing solution, and the present invention was completed.

  That is, the pretreatment method for electroless plating of the present invention includes a first step of bringing a solution containing a nonionic surfactant into contact with a conductor pattern having a predetermined shape formed on the surface of a substrate, and the first step. And a second step of bringing the conductive pattern after the step into contact with a solution containing a cationic surfactant.

  By adopting such a pretreatment method, the deposition of electroless plating to areas other than the conductor pattern is sufficiently suppressed, and the factor that can sufficiently cover the conductor pattern with the electroless plating film is currently However, details are not disclosed. The present inventors estimate as one of the factors as follows, but the factor is not limited to this. That is, first, in the first step, the surface of the substrate is degreased, and further, through the second step, the substrate surface is considered to have a positive charge due to, for example, the remaining cationic surfactant. Thereby, it is estimated that adsorption | suction to the area | regions other than the conductor pattern of the chemical species which has positive charges, such as a palladium-type catalyst, can be prevented. On the other hand, the chemical species are adsorbed on the conductor pattern because it is easier to remove the cationic surfactant in the conductor pattern than in other regions.

  The pretreatment method for electroless plating according to the present invention includes a third step of performing a soft etching process on the conductor pattern after the second step, a fourth step of washing the conductor pattern with dilute acid after the third step, and a fourth step. You may have the 5th process of making a palladium compound containing solution contact a conductor pattern after a process.

  In the pretreatment method of electroless plating of the present invention, the nonionic surfactant is preferably polyoxyethylene alkylphenyl ether, and the cationic surfactant is preferably alkylmethylammonium chloride. By using these surfactants, an electroless nickel plating film can be selectively formed on the conductor pattern.

  For the same reason, in the pretreatment method of electroless plating of the present invention, the concentration of the nonionic surfactant in the solution containing the nonionic surfactant is preferably 0.1 to 20 g / L, The concentration of the cationic surfactant in the solution containing the surfactant is preferably 1 to 100 g / L.

  The electroless plating method of the present invention includes a nickel plating step of forming an electroless nickel film on a conductor pattern subjected to the above-described electroless plating pretreatment method. Furthermore, there may be a gold plating step of forming an electroless gold plating film on the surface of the obtained electroless nickel plating film.

  According to the present invention, the electroless plating pretreatment method and the electroless method capable of sufficiently suppressing deposition of electroless plating on regions other than the conductor pattern and sufficiently covering the conductor pattern with the electroless plating film. A nickel plating method can be provided.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIG. In the preferred electroless plating method of the present invention, a pretreatment step S10 for pretreating a conductor pattern having a predetermined shape formed on the surface of a substrate, and an electroless plating film is formed on the conductor pattern. And a plating step S20. The pretreatment step S10 corresponds to the pretreatment method for electroless nickel plating according to the present invention, and a wiring board obtained by forming a conductor pattern on a substrate is immersed in a nonionic surfactant-containing aqueous solution. 1st process S1, 2nd process S2 immersed in a cationic surfactant containing solution, 3rd process S3 which performs a soft etching process, 4th process S4 wash | cleaned with a dilute acid, In a palladium compound containing solution And 5th process S5 immersed in. The plating step S20 includes a sixth step S6 for forming an electroless nickel plating film on the conductor pattern and a seventh step S7 for forming an electroless gold plating film on the nickel plating film. Furthermore, between each process, in order to remove the excess liquid remaining on the wiring board used in the previous process, there is an eighth step S8 for washing the wiring board using running water or the like. Hereinafter, each process mentioned above is explained in full detail.

  First, before the first step S1, a wiring board in which a conductor pattern that is a material to be plated is formed on a substrate is prepared. The wiring board is obtained, for example, by forming a conductor pattern made of a material such as silver or copper on a ceramic or resin substrate by a printing method or an etching method.

(First step S1)
In the first step S1, the wiring board prepared as described above is immersed in a nonionic surfactant-containing aqueous solution to mainly perform degreasing cleaning of the conductor pattern.

The nonionic surfactant is not particularly limited. For example, as a raw material for a hydrophobic group, a higher alcohol, a thioalcohol, an alkylphenol, a polypropylene glycol, a higher fatty acid, a higher amine, a higher fatty acid amide, or an oil and fat, and a hydrophilic group raw material Examples thereof include those obtained using polyethylene glycol, alkylene oxide, glycerin, sorbitol sucrose, or diethanolamine. Among them, polyoxyalkylene alkyl ether and polyoxyalkylene alkyl phenyl ether obtained by using higher alcohol or alkylphenol as a raw material for hydrophobic group and alkylene oxide as a raw material for hydrophilic group are preferable, and polyoxyalkylene alkyl phenyl ether is preferable. Is more preferable. As polyoxyalkylene alkylphenyl ether, for example, polyoxyethylene alkylphenyl ether can be used, and this molecule may have an oxypropylene group (—OC ₃ H ₆ —).

  As the alkyl group in the molecule of polyoxyethylene alkylphenyl ether, those having about 7 to 10 carbon atoms are preferable, and as polyoxyethylene alkylphenyl ether having such an alkyl group, for example, polyoxyethylene isooctylphenyl Examples include ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, and the like.

  The concentration of the nonionic surfactant in the aqueous solution containing a nonionic surfactant varies depending on the type of nonionic surfactant used, but is preferably 0.1 to 20 g / L, and preferably 1 to 5 g / L. And more preferred. When the concentration of the nonionic surfactant is less than 0.1 g / L, it is difficult to obtain the degreasing cleaning effect of the conductor pattern as the material to be plated, and the subsequent process is caused by residual dirt on the conductor pattern. Therefore, it tends to cause uneven deposition of electroless nickel plating and poor adhesion. On the other hand, when the concentration of the nonionic surfactant exceeds 20 g / L, further improvement in the degreasing and cleaning effect of the conductor pattern is not observed, and it becomes difficult to obtain product properties that meet the manufacturing cost. Furthermore, since the nonionic surfactant is likely to remain on the surface of the conductor pattern, if the subsequent water washing (water washing) is insufficient, the electroless nickel plating may be unevenly deposited in a later step. It tends to cause poor adhesion.

  Further, when the nonionic surfactant-containing aqueous solution contains an alkaline salt such as sodium hydroxide or potassium hydroxide in addition to the nonionic surfactant, the pH of the conductive pattern is increased when the pH exceeds 7. This is preferable because the degreasing and cleaning effect can be further improved.

  The pH of the nonionic surfactant-containing aqueous solution is more preferably in the range of 8 to 11 by adjusting the addition amount of the alkaline salt. If the pH is less than 8, the effect of degreasing and cleaning the conductor pattern tends not to be exhibited as compared with the case where no alkaline salt is added. In addition, when the pH exceeds 11, alkaline salt tends to remain on the surface of the conductor pattern. Therefore, in the case where subsequent washing with water is insufficient, the uneven deposition of electroless nickel plating is further performed in a later step. It tends to cause poor adhesion.

  The immersion time of the wiring board in the nonionic surfactant-containing liquid is not particularly limited, and the conductor pattern can be sufficiently degreased and washed depending on the shape and dimensions of the wiring board and the conductive pattern, the concentration of the nonionic surfactant, etc. And what is necessary is just to adjust suitably to such an extent that the time of a 1st process does not become excess.

(Second step S2)
In the second step S2, the wiring board after degreasing and washing is immersed in an aqueous solution containing a cationic surfactant so that the precipitation of the palladium catalyst mainly on the area of the wiring board other than the conductor pattern can be suppressed. .

  The cationic surfactant is not particularly limited. For example, a higher fatty acid, a higher fatty acid halide, a higher fatty acid amide, a higher amine, a higher phosphine, a higher alkyl halide, or a higher alcohol is used as a hydrophobic group raw material. As raw materials, lower alkyl halides, di-lower alkyl sulfates, alkylene amines such as ethylenediamine and diethylenetriamine, alcohol amines such as ethanolamine, diethanolamine and triethanolamine, aminoalkyl alcoholamines, acids, pyridine, benzyl halides, or ethylene oxide are used. Can be obtained.

  Among them, alkylammonium halides obtained by using a higher amine as a raw material for a hydrophobic group and using a lower alkyl halide as a raw material for a hydrophilic group are preferable. As the alkylammonium halide, for example, alkylmethylammonium chloride or alkylmethylammonium bromide having at least a methyl group as an alkyl group and having a chlorine atom or a bromine atom as a halogen atom can be used. Among these, those having an alkyl group other than a methyl group having about 9 to 20 carbon atoms are preferred, and those having two or three methyl groups bonded to a nitrogen atom are preferred. More specifically, for example, decyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadodecyltrimethylammonium chloride, dioctyldimethylammonium chloride, didecyldimethylammonium chloride, didodecyldimethyl Ammonium chloride or the like, or those obtained by substituting chlorine atoms in these molecules with bromine atoms can be used.

  The concentration of the cationic surfactant in the aqueous solution containing the cationic surfactant varies depending on the type of the cationic surfactant used, but is preferably 1 to 100 g / L, and more preferably 5 to 40 g / L. preferable. When the concentration of the cationic surfactant is less than 1 g / L, the effect of improving the selectivity when the electroless nickel plating is formed on the conductor pattern is lowered in the subsequent steps, and nickel is formed in a region other than the conductor pattern. There is a tendency for plating to be easily deposited. On the other hand, when the concentration of the cationic surfactant exceeds 100 g / L, further improvement of the above-described selectivity improvement effect is not observed, and it is difficult to obtain a product property corresponding to the manufacturing cost. Furthermore, since the cationic surfactant is likely to remain on the surface of the conductor pattern, if the subsequent water washing (water washing) is insufficient, the uneven deposition of electroless nickel plating may be caused in a later step. It tends to cause poor adhesion.

  In addition to the cationic surfactant, the cationic surfactant-containing aqueous solution contains an organic acid salt such as sulfuric acid or citric acid, and is made strongly acidic with a pH of 1 or less. The effect of removing the oxide film formed on the surface is obtained.

(Third step S3)
In the third step S3, soft etching is performed by immersing the wiring board in an etching solution in order to smooth the surface of the conductor pattern on the wiring board obtained through the second step S2.

  The etching solution is not particularly limited as long as it is used for ordinary soft etching treatment. For example, an ammonium persulfate aqueous solution, a sodium persulfate aqueous solution, a sulfuric acid-hydrogen peroxide aqueous solution, or a commercially available soft etching solution is used. Can do.

(Fourth step S4)
In the fourth step S4, in order to remove the oxide film formed on the surface of the conductor pattern on the wiring board obtained through the third step S3, the wiring board is dipped in dilute acid for a relatively short time to perform acid cleaning. Do. The dilute acid is not particularly limited, and dilute sulfuric acid, dilute hydrochloric acid, dilute nitric acid and the like can be used.

(5th process S5)
In 5th process S5, the wiring board obtained through 4th process S4 is immersed in palladium compound containing aqueous solution, and metal palladium (Pd) used as a catalyst is selectively formed on the conductor pattern surface.

The palladium compound-containing aqueous solution is not particularly limited as long as it can replace the metal on the surface of the conductor pattern with Pd, and may be one used for pretreatment of conventional Ni plating. Any palladium compound may be used as long as it contains palladium ions (Pd ²⁺ ). Examples thereof include palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium oxide, and palladium sulfide. It is done.

(6th process S6)
In the sixth step S6, the wiring board obtained through the fifth step S5 is immersed in an electroless nickel plating solution to selectively form an electroless nickel plating film only on the conductor pattern.

  The electroless nickel plating solution is not particularly limited as long as it is conventionally used. Thus, for example, the electroless nickel plating solution contains an organic source such as citric acid, malonic acid or tartaric acid in addition to a nickel ion source such as nickel chloride or nickel sulfate and a reducing agent such as hypophosphite or amine boron compound. An appropriate amount of various commonly used additives such as a complexing agent such as an acid or a salt thereof, or other pH adjusting agents may be included.

  The temperature of the electroless nickel plating solution when dipping the wiring board and the dipping time of the wiring board in the plating solution can be appropriately set so that a nickel plating film having a desired film thickness can be obtained. That is, when it is desired to make the nickel plating film relatively thick, the temperature of the plating solution may be set higher and / or the immersion time of the wiring board may be lengthened. Conversely, when it is desired to make the nickel plating film relatively thin, the temperature of the plating solution may be set low and / or the immersion time of the wiring board may be shortened. However, the film thickness of the nickel plating film needs to be a film thickness that does not expose the conductor pattern below it.

  In this step S6, nickel ions are reduced on the catalyst by the action of the catalyst on the conductor pattern of the wiring board to form a nickel plating film.

(Seventh step S7)
In the seventh step S7, a gold plating film is formed on the nickel plating film by immersing the wiring board obtained through the sixth step S6 in a displacement gold plating solution.

  The displacement gold plating solution is not particularly limited as long as it is conventionally used for forming a gold plating film on the nickel plating film by a substitution reaction between nickel and gold ions in the liquid. Thus, for example, the displacement gold plating solution is a cyanide gold ion source (gold cyanide salt) such as sodium gold cyanide or potassium gold cyanide, or non-cyanide such as gold sulfite, gold thiosulfate or gold chloride. An appropriate amount of various additives usually used in a gold ion source, a complexing agent such as sulfite or carboxylate, or other substituted gold plating solution may be included.

  Although the temperature of the displacement gold plating solution at the time of wiring board immersion can be suitably set so that the displacement gold plating film of a desired film thickness can be obtained, it is preferable that it is about 80-90 degreeC. When the temperature of the displacement gold plating solution is lower than 80 ° C., the deposition rate of gold tends to be too slow, and when it is higher than 90 ° C., the displacement gold plating solution volatilizes quickly, or a component in the plating solution. Is thermally decomposed, the stability of gold ions in the liquid tends to be remarkably reduced.

  The pH of the displacement gold plating solution is 5 to 7 when a cyanide gold ion source is contained from the viewpoint of ensuring the stability of the plating solution or ensuring the thickness of the displacement gold plating film, and a non-cyanide gold ion source. When it contains, it is preferable that it is 6-9.

  And the immersion time of the wiring board in this plating solution can be suitably set so that the substitution gold plating film of a desired film thickness can be obtained. That is, when it is desired to make the displacement gold plating film relatively thick, the immersion time of the wiring board in the plating solution may be increased. Conversely, when it is desired to make the displacement gold plating film relatively thin, the immersion time of the wiring board in the plating solution may be shortened. However, when a substitution gold plating process is performed, after a gold plating film having a certain thickness (about 30 to 100 nm) is formed, the film thickness of the film tends to hardly change even if immersed for a longer time. Therefore, it is preferable to set the immersion time from the viewpoint of reducing the manufacturing cost in consideration of this.

  In the electroless plating method of the present embodiment described above, the first step S1 for immersing the wiring board in the aqueous solution containing a nonionic surfactant and the second step S2 for immersing in the aqueous solution containing a cationic surfactant are performed in this order. By doing so, it becomes possible to selectively form an electroless plating film only on the conductor pattern.

  The present inventors performed each process after the third step S3 after immersing the wiring board in an aqueous solution in which a nonionic surfactant and a cationic surfactant were mixed. As a result, the conductor pattern on the wiring board was obtained. It was experimentally confirmed that an electroless plating film was formed in a region other than (see Comparative Example 5).

  Furthermore, the present inventors have provided the nonionic surfactant-containing aqueous solution after the first step S1 and the second step S2 are reversed, that is, after the wiring board is immersed in the cationic surfactant-containing aqueous solution. It was experimentally confirmed that an electroless plating film was formed in a region other than the conductor pattern on the wiring board when immersed in (see Comparative Example 4).

  The following factors can be considered as these factors, but the factors are not limited thereto. That is, it is considered that the cationic surfactant adsorbs relatively strongly to the insulator (dielectric), but does not adsorb so strongly to the conductor. Due to this, when the wiring board is immersed in an aqueous solution containing a cationic surfactant, it is presumed that the cationic surfactant is selectively adsorbed only in a region other than the conductor pattern. In addition, it is presumed that the cationic surfactant has an action to repel metal ions. As a result, when the wiring board is immersed in an aqueous solution containing a palladium compound, metallic palladium is selectively formed only on the conductor pattern, and as a result, the electroless plating film is also selectively only on the conductor pattern. It is thought that it is formed.

  On the other hand, when a mixed aqueous solution of a nonionic surfactant and a cationic surfactant is used, or when the first step S1 and the second step S2 are reversed, the conductive pattern other than the cationic surfactant is used. It is considered that the effect of suppressing the formation of plating on this region is reduced by mixing with a nonionic surfactant or subsequent treatment with a nonionic surfactant. As a result, the present inventors presume that it becomes difficult to form a selective electroless plating film on the conductor pattern.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the electroless plating method of the present invention, in order to bring the wiring board into contact with each solution, the solution may be sprayed or applied to the wiring board in addition to the immersion treatment in the solution. Further, depending on the use of the wiring board, the seventh step S7 (electroless gold plating) may be omitted.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

Example 1
As the wiring board for plating test of this example, a copper substrate (pattern interval: 50 to 100 μm) formed by a tenting method on a 10 cm × 10 cm × 1 mm ceramic substrate was used.

  First, an aqueous solution containing 0.1 g / L of polyoxyethylene nonylphenyl ether was prepared as a nonionic surfactant aqueous solution. The obtained aqueous solution was heated to 50 ° C. and maintained at that temperature, and the above-mentioned wiring board was immersed in the aqueous solution for 4 minutes (first step). Next, the wiring board was washed with pure water at 50 ° C. for 1 minute, and further washed with pure water at room temperature for 4 minutes.

  Next, an aqueous solution containing 20 g / L of octadodecyltrimethylammonium chloride was prepared as an aqueous cationic surfactant solution. The obtained aqueous solution was heated to 40 ° C. and maintained at that temperature, and the washed wiring board was immersed in the aqueous solution for 3 minutes (second step). Next, the wiring board was washed with pure water at 50 ° C. for 1 minute, and further washed with pure water at room temperature for 4 minutes.

  Subsequently, the obtained wiring board was immersed in a room temperature ammonium persulfate aqueous solution (concentration: 100 g / L) for 30 seconds, subjected to a soft etching process (third step), and further washed with pure water at room temperature for 1 minute. did. Next, in order to remove the oxide film on the copper pattern, the obtained wiring board is immersed in 10% dilute sulfuric acid at room temperature for 1 minute and washed with acid (fourth step), and further with pure water at room temperature for 1 minute. Washed.

  Next, the wiring board is immersed for 5 minutes in a substituted palladium catalyst solution SA-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.) which is an aqueous solution containing a palladium compound at room temperature (fifth step), and further with pure water at room temperature. Washed for 1 minute. Then, the wiring board is immersed in an electroless nickel plating solution NIPS-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.) at 85 ° C. for 25 minutes to form a nickel plating film having a thickness of 5 μm on the wiring board. Then, a plating-formed wiring board according to Example 1 was obtained.

(Example 2)
In the same manner as in Example 1, except that an aqueous solution containing 3.0 g / L polyoxyethylene nonylphenyl ether was used instead of the aqueous solution containing 0.1 g / L polyoxyethylene nonylphenyl ether. A plating-formed wiring board according to Example 2 was obtained.

Example 3
Example 3 was carried out in the same manner as in Example 1 except that an aqueous solution containing 20 g / L of polyoxyethylene nonylphenyl ether was used instead of the aqueous solution containing 0.1 g / L of polyoxyethylene nonylphenyl ether. The plating formation wiring board concerning was obtained.

Example 4
In the same manner as in Example 1, except that an aqueous solution containing 0.01 g / L polyoxyethylene nonylphenyl ether was used instead of the aqueous solution containing 0.1 g / L polyoxyethylene nonylphenyl ether. A plating-formed wiring board according to Example 4 was obtained.

(Example 5)
Example 5 was carried out in the same manner as in Example 1 except that an aqueous solution containing 50 g / L of polyoxyethylene nonylphenyl ether was used instead of the aqueous solution containing 0.1 g / L of polyoxyethylene nonylphenyl ether. The plating formation wiring board concerning was obtained.

(Example 6)
Instead of an aqueous solution containing 0.1 g / L polyoxyethylene nonylphenyl ether, an aqueous solution containing 0.1 g / L polyoxyethylene octylphenyl ether was used, and 20 g / L octadodecyltrimethylammonium chloride was contained. A plating-formed wiring board according to Example 6 was obtained in the same manner as in Example 1 except that an aqueous solution containing 20 g / L of dodecyltrimethylammonium chloride was used instead of the aqueous solution.

(Example 7)
In the same manner as in Example 6, except that an aqueous solution containing 3.0 g / L polyoxyethylene octylphenyl ether was used instead of the aqueous solution containing 0.1 g / L polyoxyethylene octylphenyl ether. A plating-formed wiring board according to Example 7 was obtained.

(Example 8)
Example 8 was carried out in the same manner as in Example 6 except that an aqueous solution containing 20 g / L of polyoxyethylene octylphenyl ether was used instead of the aqueous solution containing 0.1 g / L of polyoxyethylene octylphenyl ether. The plating formation wiring board concerning was obtained.

Example 9
Instead of an aqueous solution containing 0.1 g / L polyoxyethylene nonylphenyl ether, an aqueous solution containing 3.0 g / L polyoxyethylene nonylphenyl ether was used, and 20 g / L octadodecyltrimethylammonium chloride was contained. A plating-formed wiring board according to Example 9 was obtained in the same manner as in Example 1 except that an aqueous solution containing 1.0 g / L of octadodecyltrimethylammonium chloride was used instead of the prepared aqueous solution.

(Example 10)
Plating according to Example 10 in the same manner as Example 9 except that an aqueous solution containing 100 g / L octadodecyltrimethylammonium chloride was used instead of the aqueous solution containing 1.0 g / L octadodecyltrimethylammonium chloride. A formed wiring board was obtained.

(Example 11)
Instead of an aqueous solution containing 0.1 g / L polyoxyethylene octylphenyl ether, an aqueous solution containing 3.0 g / L polyoxyethylene octylphenyl ether was used, and 20 g / L dodecyltrimethylammonium chloride was contained. A plating-formed wiring board according to Example 11 was obtained in the same manner as in Example 6 except that an aqueous solution containing 1.0 g / L of dodecyltrimethylammonium chloride was used instead of the aqueous solution.

(Example 12)
Plating formation according to Example 12 except that an aqueous solution containing 100 g / L of dodecyltrimethylammonium chloride was used instead of an aqueous solution containing 1.0 g / L of dodecyltrimethylammonium chloride A wiring board was obtained.

(Example 13)
Example 13 is carried out in the same manner as Example 11 except that an aqueous solution containing 0.1 g / L of dodecyltrimethylammonium chloride was used instead of the aqueous solution containing 1.0 g / L of dodecyltrimethylammonium chloride. A plating-formed wiring board was obtained.

(Example 14)
Plating formation according to Example 14 except that an aqueous solution containing 200 g / L of dodecyltrimethylammonium chloride was used instead of an aqueous solution containing 1.0 g / L of dodecyltrimethylammonium chloride A wiring board was obtained.

For the nonionic surfactant-containing aqueous solution and the cationic surfactant-containing aqueous solution according to Examples 1 to 14 described above, the types of surfactants and their concentrations are summarized in Table 1.

(Comparative Example 1)
A plating-formed wiring board according to Comparative Example 1 was obtained in the same manner as in Example 1 except that the first step and the second step were omitted.

(Comparative Example 2)
A plating-formed wiring board according to Comparative Example 2 was obtained in the same manner as in Example 1 except that the first step was omitted.

(Comparative Example 3)
A plating-formed wiring board according to Comparative Example 3 was obtained in the same manner as Example 7 except that the second step was omitted.

(Comparative Example 4)
A plating-formed wiring board according to Comparative Example 4 was obtained in the same manner as in Example 2 except that the order of the first step and the second step was reversed.

(Comparative Example 5)
A plating-formed wiring board according to Comparative Example 5 was obtained in the same manner as in Example 1 except that the first step and the second step were replaced with the steps described below. An aqueous solution containing 3.0 g / L of polyoxyethylene nonylphenyl ether as a nonionic surfactant and 20.0 g / L of octadodecyltrimethylammonium chloride as a cationic surfactant was prepared. The obtained aqueous solution was heated to 40 ° C. and maintained at that temperature, and the above-described wiring board was immersed in the aqueous solution for 3 minutes.

  About the nonionic surfactant containing aqueous solution and cationic surfactant containing aqueous solution which concern on the comparative examples 1-5 mentioned above, the kind of surfactant and its density | concentration are put together in Table 1, and are shown.

[Evaluation of plating state]
The surface of the plating forming wiring board according to Examples 1 to 14 and Comparative Examples 1 to 5 was observed with a stereomicroscope (100 times), and the formation state of the plating film on the copper pattern was evaluated in three stages A to C. Then, the formation state (deposition state) of the plating film in the region other than the copper pattern was evaluated in four stages A to D. As for the formation state of the plating film on the copper pattern, “A” when the entire surface of the pattern is covered with the plating film and no pattern exposure is observed, and when only a small part of the pattern surface is exposed. “B”, and “C” when a part of the surface of the pattern was exposed and discoloration due to it was observed.

As for the formation state of the plating film in the region other than the copper pattern, “A” indicates that the plating film is not observed, and “B” indicates that the plating film is recognized in the region of less than 5% of the entire region. "C" when the plating film is recognized in an area of 5% or more and less than 10% with respect to the entire area, and "D" when the plating film is recognized in an area of 10% or more with respect to the entire area. It was. The evaluation results are shown in Table 2.

It is a flowchart of suitable embodiment which concerns on the electroless-plating method of this invention.

Explanation of symbols

  S1 ... 1st process, S2 ... 2nd process, S3 ... 3rd process, S4 ... 4th process, S5 ... 5th process, S6 ... 6th process, S7 ... 7th process, S8 ... 8th process.

Claims (8)

A first step of bringing a solution containing a nonionic surfactant into contact with a conductor pattern having a predetermined shape formed on the surface of the substrate;
A second step of bringing the conductive pattern after the first step into contact with a solution containing a cationic surfactant;
A pretreatment method for electroless plating. A third step of performing a soft etching process on the conductor pattern after the second step;
A fourth step of washing the conductive pattern with dilute acid after the third step;
A fifth step of bringing a palladium compound-containing solution into contact with the conductor pattern after the fourth step;
The pretreatment method for electroless plating according to claim 1, comprising:   The pretreatment method for electroless plating according to claim 1 or 2, wherein the nonionic surfactant is polyoxyethylene alkylphenyl ether.   The pretreatment method for electroless plating according to any one of claims 1 to 3, wherein the cationic surfactant is alkylmethylammonium chloride.   Before the electroless plating according to any one of claims 1 to 4, wherein the concentration of the nonionic surfactant in the solution containing the nonionic surfactant is 0.1 to 20 g / L. Processing method.   The pretreatment method for electroless plating according to any one of claims 1 to 5, wherein the concentration of the cationic surfactant in the solution containing the cationic surfactant is 1 to 100 g / L. .   An electroless plating method comprising a nickel plating step of forming an electroless nickel plating film on the surface of the conductor pattern subjected to the electroless plating pretreatment method according to claim 1.   The electroless plating method according to claim 7, further comprising a gold plating step of forming an electroless gold plating film on a surface of the electroless nickel plating film.

Images