JP2005054256A - Post treatment liquid for surface of tin or tin alloy plating, and posttreatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration with the lapse of time in solder wettability on posttreatment for the surface of tin or tin alloy plating and to quicken and simplify the posttreatment. <P>SOLUTION: The posttreatment liquid is used to the posttreatment for a tin based plating face after the formation of a tin or tin alloy plating film on an object to be plated, and comprises at least one kind of resin for posttreatment selected from the group consisting of an acrylic resin, a maleic resin, an alkyd resin and a phenol resin having the average molecular weight in a specified range. Since the tin based plating face is surface-treated with the posttreatment liquid comprising the specified resin for posttreatment having the limited average molecular weight, deterioration with lapse of time in solder wettability in the plating face with the lapse of time can be prevented. Further, the deterioration in the solder wettability with the lapse of time can further effectively be prevented by limiting the acid value and softening point, the equivalent of hydroxyl groups and softening point or oil length in the resin for the posttreatment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a post-treatment liquid for the plating surface and a post-treatment method for the plating surface using the post-treatment liquid, while ensuring good solder wettability of the plating surface without causing deterioration over time, and rapid post-treatment. Provide what can be simplified.

The surface of the metal easily deteriorates with time due to oxidation, and oxidation is particularly promoted in a humid and high temperature state.
Therefore, conventionally, an organic film is applied to the metal surface to prevent the surface from being rusted.
For example, Patent Document 1 discloses that after a film mainly composed of chromium hydrated oxide is formed on a metal substrate on which a plated film such as a tin-plated steel sheet or a steel sheet having a chromate film is formed, (a) dehydrated castor oil, flaxseed Oils and oils such as soybean oil, blended with alkylphenol resins and epoxy resins, and maleated resins, or (b) polyhydric alcohols such as glycerin and trimethylolpropane, and phthalic acid, maleic acid, succinic acid Alkyd resin reacted with dibasic acid such as acid, (c) copolymer of acrylic acid, methacrylic acid and methyl acrylate, copolymer of acrylic acid, alkyl ester of methacrylic acid and vinyl toluene It is disclosed that a thin film layer of a water-soluble resin made of an acrylic resin or the like is formed (see claims), but this is applied to a steel sheet with a paint. Or, in order to increase the paint adherence, etc. when coating the laminate film.

On the other hand, when soldering a metal material, in order to ensure solder wettability, a plating film such as tin or a tin alloy is generally formed in advance on the metal material. Oxidation is likely to cause deterioration over time, and surface properties are impaired along with discoloration and the like.
Therefore, techniques for post-processing the plating surface for the purpose of improving the surface characteristics are known, and the conventional techniques are as follows.
First, Patent Document 2 discloses a water-dispersible or water-soluble organic material comprising an acrylic resin, an alkyd resin, a maleic acid resin, an unsaturated polyester resin, or a urethane resin for the purpose of improving solderability, solder aging, corrosion resistance, and the like. A method of post-treating a plated steel sheet subjected to zinc or zinc alloy plating with an aqueous solution containing a resin, hexavalent chromium ions, and a rosin amine salt is disclosed (see claims, paragraphs 1 and 3). .

Japanese Patent Publication No.52-35620 JP-A-9-234421

Even if the plating surface is post-treated with a solution containing a water-soluble or water-dispersible resin such as acrylic resin, maleic acid resin, alkyd resin, etc. described in Patent Documents 1 and 2, the solder wettability of the plating surface is sufficient In addition, there is a risk that dust may be adsorbed by the treated oil film and other products may be contaminated with oil in the oil film.
In the post-treatment of the plating surface, the present invention has a technical problem of ensuring good solder wettability and quick and simple post-treatment.

  When the present inventors apply these resins to the post-treatment of the tin or tin alloy plating surface, mainly the acrylic resin, alkyd resin, etc. described in the above Patent Documents 1 and 2, solder wettability is achieved. As a result of earnest research on the effectiveness of the application, the average molecular weight of these resins has a great influence on ensuring solder wettability of the plating surface, and then the acid value, softening point, hydroxyl equivalent, oil length, etc. of the resin Is important for imparting solder wettability, and if the above resin is made into a salt form with ammonia or a low boiling point amine, it is necessary to use alcohol for the purpose of dissolution, which promotes water solubility and has a risk of fire. In addition, the present invention has been completed by discovering that ammonia or amine easily evaporates during the drying process following the post-treatment, and that the soldering operation can be secured well.

That is, the present invention 1 is a liquid for post-treating the plating surface after forming a tin or tin alloy plating film on an object to be plated,
Containing at least one kind of post-treatment resin selected from the following (A) to (C):
(A) Acrylic resin or maleic resin having an average molecular weight of 2000 to 50000
(B) Alkyd resin having an average molecular weight of 500 to 5,000
(C) A phenol resin having an average molecular weight of 300 to 2,000, and a post-treatment liquid for tin or tin alloy plating surface characterized by not containing chlorine and chromium.

  Invention 2 is the invention 1, wherein the acrylic resin has an acid value of 100 to 500, a softening point of 80 to 200 ° C, a maleic acid resin has an acid value of 100 to 300, and a softening point of 80 to 200 ° C. A tin or tin alloy plating surface post-treatment liquid, wherein the oil length of the alkyd resin is 35 to 55%, the hydroxyl equivalent of the phenol resin is 130 to 1000, and the softening point is 90 to 200 ° C.

  Invention 3 is a post-treatment liquid for a tin or tin alloy plating surface according to Invention 1 or 2, wherein the post-treatment resin is reacted with ammonia or a low boiling point amine to form an ammonium salt or an amine salt.

  Invention 4 is the invention according to any one of Inventions 1 to 3, wherein the tin alloy is composed of tin, bismuth, copper, zinc, nickel, silver, gold, indium, antimony, lead, cobalt, thallium, and gallium. A post-treatment liquid for tin or a tin alloy plating surface, which is an alloy with at least one selected metal.

  The present invention 5 is a tin or tin alloy plating characterized in that after the tin or tin alloy plating film is formed on the object to be plated, the plating surface is brought into contact with the post-treatment liquid according to any one of the present inventions 1 to 4 This is a surface post-treatment method.

  The present invention 6 includes a semiconductor device, a printed board, a flexible printed board, a film carrier, a connector, a switch, a resistor, a variable resistor, a capacitor, a filter, an inductor, a thermistor, a crystal resonator, and the post-processing method of the present invention 5 described above. Electronic components such as lead wires.

As described above, when soldering a metal material such as an electronic component, a plating film such as tin or a tin alloy is formed in advance in order to ensure solder wettability. It tends to deteriorate over time.
In the present invention, a liquid containing a specific post-treatment resin such as an acrylic resin having an average molecular weight in a specific range, an alkyd resin, or the like, so that the tin or tin alloy plating surface is contact-treated, without causing the above-mentioned deterioration over time, Solder wettability of the plated surface can be maintained well.
Although the detailed mechanism is still unclear, the carboxyl group of the acrylic resin, maleic resin or alkyd resin, or the hydroxyl group of the phenol resin exerts some chemical bonding action on the plating film. The solder wettability of the post-processed plated surface does not deteriorate over time in order to effectively prevent the bulky lipophilic part from firmly adhering to the plating film and effectively oxidizing the plated surface with outside air or water. Presumed.

The post-treatment liquid of the present invention can be made into an organic solvent liquid, an alcohol solution, a hydrous alcohol solution, or an aqueous solution by dissolving the above active ingredients in various solvents such as aromatic hydrocarbons and alcohols or water. Therefore, the active ingredient can be uniformly adsorbed on the plated surface, and the solder wettability can be maintained well.
In this case, if the post-treatment resin is made into a salt with a base such as ammonia or amine, the amount of alcohol used can be reduced due to increased water solubility even if the post-treatment liquid is in the form of an alcohol or a hydrous alcohol solution. Eliminates the danger of ignition and contributes to environmental conservation and occupational health. In particular, use of ammonia or a low boiling point amine is advantageous because it is easily volatilized by heat drying after the post-treatment.
On the other hand, specifying the softening point, acid value, oil length, or hydroxyl equivalent of the above-mentioned post-treatment resin contributes to the prevention of further deterioration of solder wettability over time, and in particular, the softening point is limited to a specific range. By doing so, there is no stickiness of the plated surface when post-processing, and since it volatilizes quickly at the time of soldering, it is excellent in solderability. In addition, the resin does not separate from the protective surface due to the increase in fluidity that occurs as the temperature rises.

  In the present invention, first, a tin or tin alloy plating surface containing, as an active ingredient, a post-treatment resin selected from the group consisting of an acrylic resin, a maleic acid resin, an alkyd resin, and a phenol resin having an average molecular weight in a specific range. A post-treatment liquid; second, a method of post-treating the plated surface of the object to be plated with the post-treatment liquid; and third, an electronic component such as a printed circuit board or a semiconductor integrated circuit to which the post-treatment method is applied. It is.

The average molecular weight of the acrylic resin of the present invention is 2000 to 50000, preferably 5000 to 30000. Specific examples of the acrylic resin are as follows (1) to (3).
(1) Polymer or copolymer obtained by polymerizing or copolymerizing acrylic acid, methacrylic acid, crotonic acid, acrylic ester, methacrylic ester, crotonic ester, acrylamide, methacrylamide, acrylonitrile, etc. The ester of is an esterified product such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, iso-butyl, t-butyl, amyl, ethylhexyl, octyl, etc. (the same applies to the ester of (2) below).
(2) Copolymers obtained by copolymerizing acrylic acid, methacrylic acid, crotonic acid, acrylic acid ester, methacrylic acid ester, crotonic acid ester, acrylamide, methacrylamide, acrylonitrile, etc. with urethane, styrene, vinylidene chloride, etc.
(3) An acrylic resin obtained by modifying the resin of (1) to (2) with an alkyd resin, an epoxy resin, a phenol resin, or the like. The acrylic resin is an unsaturated compound such as acrylic acid, for example, a reaction temperature of 70 to 150 ° C. The reaction is carried out by a known method starting with a reaction time of 2 to 10 hours.
If the average molecular weight of the acrylic resin is less than 2000, sufficient solder wettability cannot be obtained, and if it exceeds 50000, the film remains without being completely vaporized during soldering, which may adversely affect the solder wettability. .
As shown in the present invention 2, from the viewpoint of preventing deterioration of solder wettability with time, the acid value of the acrylic resin is 100 to 500, preferably 150 to 500, and the softening point is 80 to 200 ° C, preferably 110 to 200 ° C. It is.
The acid value of the post-treatment resin is related to a mechanism for preventing deterioration of solder wettability over time on the plated surface, and the above appropriate range is required for manufacturing reasons. If the softening point is lower than 80 ° C., the surface becomes sticky, and organic matter and dust are likely to adhere in the heating and drying process following the post-treatment, which may adversely affect the solderability and increase in temperature. There is also a risk of separation from the protective surface due to increased fluidity. On the other hand, when the temperature is higher than 200 ° C., it is difficult to melt at the time of soldering, and it may remain without volatilizing and adversely affect soldering.

The maleic acid resin of the present invention is a copolymer obtained by copolymerizing maleic anhydride or maleic ester with olefin, styrene, vinyl acetate or the like, and has an average molecular weight of 2000 to 50000, preferably 5000 to 30000 Say.
The maleic resin is produced by reacting an unsaturated compound such as maleic anhydride with a known method such as a reaction temperature of 70 to 150 ° C. and a reaction time of 2 to 10 hours.
If the average molecular weight of the maleic resin is too small, sufficient solder wettability cannot be prevented over time, and if it is too large, the film will remain completely vaporized during soldering, which will adversely affect solder wettability. There is a risk.
As shown in the present invention 2, from the viewpoint of preventing deterioration of solder wettability with time, the acid value of the maleic acid resin is 100 to 300, preferably 150 to 300, and the softening point is 80 to 200 ° C., preferably 110 to 200. ° C.

The alkyd resin of the present invention is a polybasic acid-polyhydric alcohol condensate or a modified product further reacted with a modifying agent and has an average molecular weight of 500 to 5,000, preferably 1,000 to 3,000.
Examples of the polybasic acid include (anhydrous) phthalic acid, terephthalic acid, isophthalic acid, (anhydrous) trimellitic acid, adipic acid, succinic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, citraconic acid and the like. .
Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, neopentyl glycol, glycerin, diglycerin, trimethylolpropane, and bisphenol A.
Examples of the modifier include soybean oil, linseed oil, tung oil, rosin, ester gum, stearic acid, phenol, styrene, and isocyanate.
The alkyd resin is produced by a known method such as a fatty acid method or a transesterification method using the polybasic acid and a polyhydric alcohol. The general reaction temperature is 150 to 230 ° C., and the reaction time is 2 to 10 hours, but is not particularly limited thereto. Furthermore, as described above, this product can be made into a modified product by reacting with the above-mentioned modifying agent.
If the average molecular weight of the alkyd resin is too small, the effect of preventing sufficient solder wettability over time cannot be obtained, and if it is too large, the film remains without being completely vaporized during soldering, adversely affecting the solder wettability. There is a fear.
As shown in the present invention 2, the oil length of the alkyd resin is 35 to 55%, preferably 38 to 50% from the viewpoint of preventing the solder wettability from aging.

Phenolic resins of the present invention is phenol, phenol C ₁ -C ₁₂ alkyl groups such as cresol and xylenol were replaced, resorcinol, bisphenol A, F, B, etc. and, addition condensate (resol type with formalin, novolac type Any), or a modified phenolic resin obtained by further modifying the condensate with rosin, ester gum, drying oil or the like and having an average molecular weight of 300 to 2000, preferably 400 to 1200.
For example, if the phenol resin is a resol type, the phenols and formalin are reacted in the presence of an alkali catalyst under the conditions of a reaction temperature of 40 to 100 ° C. and a reaction time of 1 to 10 hours. Manufactured by.
If the average molecular weight of the phenol resin is too small, sufficient solder wettability cannot be obtained, and if it is too large, the film remains without being completely vaporized during soldering, which may adversely affect the solder wettability.
As shown in the present invention 2, from the viewpoint of preventing deterioration of solder wettability with time, the hydroxyl equivalent of the phenol resin is 130 to 1000, preferably 200 to 500, and the softening point is 90 to 200 ° C, preferably 110 to 200 ° C. It is.

The post-treatment resin of the present invention is prepared as a post-treatment liquid by adding it to an organic solvent and water. The above post-treatment resin may be dissolved as it is in an organic solvent such as methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, n-butyl acetate, chloroform, or post-treatment. The carboxyl group of the resin may be partially esterified and dissolved in alcohol or a mixture of alcohol and water.
In this case, the use of organic solvents such as alcohol presents a risk of ignition, and there are also problems in terms of environmental protection and occupational health (partial esters can reduce the amount of alcohol used for dissolution and are soluble in hydrous alcohols. The adverse effect can be alleviated to some extent). However, when ammonia or amine is allowed to act on the post-treatment resin to form a salt to increase the water solubility, the handling property of the post-treatment liquid is improved. Examples of the amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, isopropylamine, diisopropylamine, triisopropylamine, butylamine, piperidine, ethylenediamine, 1,2- Examples include propanediamine, morpholine, 1,3-propanediamine, cyclohexylamine, piperazine, tetramethyl-1,3-propanediamine, tetramethylethylenediamine, dimethylethanolamine, ethanolamine, and tetramethylenediamine.
Incidentally, although it is conceivable to form a salt form with an alkali metal salt, ammonia or an amine salt is preferable because the alkali metal salt is alkaline and may corrode the plated surface.
The plated surface subjected to the post-treatment of the present invention is heat-dried and then soldered. As shown in the present invention 3, ammonia or a low-boiling amine is allowed to act on the post-treatment resin to form an ammonium salt. Alternatively, in the form of a low-boiling amine salt, a portion of these salts is smoothly evaporated in this drying step, and impure components that adversely affect solder wettability can be eliminated.
Further, as the form of the post-treatment liquid, in addition to the solution in an organic solvent such as alcohol or an aqueous solution, the post-treatment liquid remains as the post-treatment resin or is partially esterified and dispersed in water. It can also be. At this time, if a surfactant is added, it remains as an impurity during heating and drying, and there is a concern that it may adversely affect the solder wettability, but there is an advantage that the uniform dispersibility of the liquid is improved.

The post-treatment resin of the present invention is an acrylic resin, a maleic acid resin, an alkyd resin, or a phenol resin, but these resins may be used singly or in combination, and a plurality of types such as an acrylic resin and an alkyd resin may be used. Needless to say, these resins may be used in combination.
In the post-treatment liquid of the present invention, the content of the post-treatment resin is appropriately 0.001 to 10% by weight, preferably 0.001 to 3% by weight. As the post-treatment liquid, a concentration of about 0.1 to 1% by weight is more practical, and 3% by weight or more is a considerably high level.
The post-treatment liquid of the present invention may contain various additives such as a rust inhibitor, an antioxidant, and a pH adjuster in addition to the surfactant.
Examples of the surfactant include monoalkyl phosphate esters and dialkyl phosphate esters, as well as various nonionic, anionic, amphoteric, and cationic surfactants.
Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl benzene sulfonates, and alkyl naphthalene sulfonates. Examples of the cationic surfactant include mono-trialkylamine salts, dimethyldialkylammonium salts, and trimethylalkylammonium salts. Examples of the nonionic surfactant, C ₁ -C ₂₀ alkanols, phenol, naphthol, bisphenol, C ₁ -C ₂₅ alkyl phenols, aryl phenols, C ₁ -C ₂₅ alkyl naphthol, C ₁ -C ₂₅ alkoxyl phosphoric acid (salt ), Sorbitan esters, polyalkylene glycols, C ₁ -C ₂₂ aliphatic amides and the like, and 2-300 mol addition-condensation of ethylene oxide (EO) and / or propylene oxide (PO). Examples of amphoteric surfactants include carboxybetaine, imidazoline betaine, sulfobetaine, and aminocarboxylic acid.
As the surfactant, monoalkyl phosphate ester, dialkyl phosphate ester and the like are preferable. However, the above-mentioned adverse effects are considered for the surfactant.
In addition, since the post-treatment liquid of the present invention contains a specific post-treatment resin as an active ingredient, corrosive chlorine and chromium which is a main component of chromic acid treatment (chromate treatment) which is a well-known metal surface treatment method are These are not included in the post-treatment liquid, and naturally both of them are excluded.

The present invention 5 is a post-treatment method of a tin or tin alloy plating surface using the post-treatment liquid. After forming a plating film on an object to be plated such as made of copper or copper alloy, the post-treatment liquid is applied to this plating solution. This is done by contacting the surface. In addition, since the plating surface used as the object of the post-treatment of the present invention includes a plating surface that has been subjected to post-treatment such as phosphoric acid treatment that has been conventionally used, a known post-treatment such as phosphoric acid treatment was applied. Later, the post-treatment of the present invention can be performed.
The tin alloy is at least one metal selected from the group consisting of tin and bismuth, copper, zinc, nickel, silver, gold, indium, antimony, lead, cobalt, thallium, and gallium, as shown in the present invention 4. For example, tin-copper alloy, tin-copper-bismuth alloy, tin-silver alloy, tin-bismuth alloy, tin-bismuth-silver alloy, tin-zinc alloy, tin-lead alloy, tin-cobalt Alloys, tin-thallium alloys, tin-gallium alloys, and the like.
The object to be plated is not particularly limited, but as shown in the present invention 6, semiconductor devices, printed boards, flexible printed boards, film carriers, connectors, switches, resistors, variable resistors, capacitors, filters, inductors, thermistors, crystal vibrations Representative examples are electronic parts such as a child and lead wires.

The above contact method is based on immersing the plating material in the post-treatment liquid, but the post-treatment liquid may be applied to the plating material or may be sprayed.
Although the time of post-processing is not specifically limited, For example, it is 1 second-60 minutes, and the temperature of a liquid is 0 degreeC-80 degreeC. A preferred treatment time is 1 second to 1 minute, and a preferred temperature is around room temperature.
The processing time can be appropriately increased or decreased depending on the processing temperature, and the processing time and temperature can be appropriately selected according to the shape and material of the plating material.

Hereinafter, preparation examples of the post-treatment liquid of the present invention, examples of post-treatment of the tin or tin alloy plating surface using the treatment liquid, and solder wettability test examples of the plating surface subjected to the post-treatment method will be described. To do.
The present invention is not limited to the following examples and test examples, and it is needless to say that arbitrary modifications can be made within the scope of the technical idea of the present invention.

<< Preparation example of post-treatment liquid >>
Among the following Preparation Examples 1 to 10, Preparation Examples 1 to 3 are usage examples of acrylic resins. Preparation Example 4 is an example of a maleic acid resin. Preparation Examples 5 to 7 are examples in which an alkyd resin is used alone, and Preparation Example 10 is a combination example of an alkyd resin. Preparation Examples 8 to 9 are examples of using phenol resins.
On the other hand, of Comparative Preparation Examples 1 to 9, Comparative Preparation Example 1 is a blank example in which no post-treatment liquid is prepared. Comparative Preparation Example 2 is an example using an acrylic resin having an average molecular weight exceeding the upper limit of the specific range of the present invention, and Comparative Preparation Example 3 is an example using an acrylic resin having an average molecular weight less than the lower limit of the same range. Comparative Preparation Example 4 is an example using a maleic acid resin whose average molecular weight exceeds the upper limit of the specific range of the present invention, and Comparative Preparation Example 5 is an example of using a maleic resin having an average molecular weight less than the lower limit of the same range. Comparative Preparation Example 6 is an example using an alkyd resin whose average molecular weight exceeds the upper limit of the specific range of the present invention, and Comparative Preparation Example 3 is an example of using an alkyd resin having an average molecular weight less than the lower limit of the same range. Comparative Preparation Example 8 is an example using a phenol resin having an average molecular weight exceeding the upper limit of the specific range of the present invention, and Comparative Preparation Example 9 is an example using a phenol resin having an average molecular weight less than the lower limit of the same range.

(1) Preparation Example 1
250 ml of n-butanol was added to a four-necked flask equipped with a thermometer, a dropping funnel, a stirrer, a cooler, and a nitrogen introduction tube, and heated to 105 ° C. with stirring. Next, a mixture of 105 g of acrylic acid, 50 g of styrene and 8 g of benzoyl peroxide was placed in the dropping funnel and dropped in 4 hours. After further reacting at the same temperature for 3 hours and allowing to cool, 400 ml of n-butanol was added to obtain an acrylic-styrene resin solution having a solid content of 25%, an average molecular weight of 7400, an acid value of 350, and a softening point of 150 ° C. .
This resin solution was diluted with isopropyl alcohol (IPA) to obtain an IPA solution of acrylic-styrene resin having a solid content concentration of 0.1% by weight.

(2) Preparation Example 2
In accordance with Preparation Example 1, acrylic acid and vinylidene chloride are used as monomer components, and an acrylic-vinylidene chloride resin (vinylidene chloride 40 mol%) solution having an average molecular weight of 20,000, an acid value of 250, and a softening point of 170 ° C. is obtained. It was.
This resin solution was diluted with toluene to obtain a toluene solution of acrylic-vinylidene chloride resin having a solid content concentration of 0.1% by weight.

(3) Preparation Example 3
Based on Preparation Example 1, acrylic acid was used as a monomer component, and an acrylic resin solution having an average molecular weight of 30,000, an acid value of 500, and a softening point of 200 ° C. was obtained.
This resin solution was diluted with a hydrous alcohol having IPA / water = 1/10 to obtain an IPA / water mixed solution of acrylic resin having a solid content concentration of 0.1% by weight.

(4) Preparation Example 4
A mixture of 690 g of monobutyl maleate, 340 g of styrene, 175 g of butyl cellosolve, 500 g of n-butanol and 20 g of azobisisobutyronitrile was charged into a nitrogen-substituted flask, heated to 120 to 130 ° C., and left at that temperature. Of 3/4 was added dropwise over 2 hours. Subsequently, a mixture of 3 g of azobisisobutyronitrile and 50 g of butyl cellosolve was added dropwise over 30 minutes. After completion of dropping, the mixture was further stirred at the same temperature for 2 hours to obtain a maleic acid-styrene resin solution having a solid content of 60%, an average molecular weight of 8600, an acid value of 215, and a softening point of 130 ° C.
This resin solution was diluted with IPA to obtain an IPA solution of maleic acid-styrene resin having a solid concentration of 0.1% by weight.

(5) Preparation Example 5
Based on Preparation Example 7 described later, linseed oil was used as the modified oil to obtain an alkyd resin having an average molecular weight of 1000 and an oil length of 43%.
This resin was diluted with xylene to obtain a xylene solution of an alkyd resin having a solid content concentration of 0.1% by weight.

(6) Preparation Example 6
Based on Preparation Example 7 described later, phenol was used as a modifier to obtain an alkyd resin solution having an average molecular weight of 3000 and an oil length of 50%.
Then, this resin was diluted with xylene to obtain a xylene solution of a phenol-modified alkyd resin having a solid content concentration of 0.1% by weight.

(7) Preparation Example 7
Tall oil fatty acid 373 g, trimethylolpropane 197 g, neopentyl glycol 78 g, bisphenol A 91 g, isophthalic acid 204 g, trimellitic anhydride 157 g and xylene 20 g were charged into a four-necked flask and heated with stirring. Next, the reaction temperature was maintained at 180 to 210 ° C., and the reaction was performed for 5 hours while removing the generated water to obtain an alkyd resin having an average molecular weight of 2100 and an oil length of 38%.
This resin was diluted with xylene to obtain a xylene solution of an alkyd resin having a solid content concentration of 0.1% by weight.

(8) Preparation Example 8
94 g of phenol, 243 g of 37% aqueous formalin solution and 160 g of 25% aqueous sodium hydroxide solution were mixed and reacted at 40 ° C. for 6 hours, then heated to 70 ° C. and reacted at that temperature for 1 hour. After the reaction, it is neutralized with hydrochloric acid and extracted with a mixed solvent of ethyl acetate / n-butanol = 1/1, and a resol type phenolic resin solution having an average molecular weight of 500, a hydroxyl value of 300, a softening point of 130 ° C., and a solid content of 80%. Got.
And this resin solution was diluted with toluene, and the toluene solution of the phenol resin with a solid content concentration of 0.1 weight% was obtained.

(9) Preparation Example 9
In accordance with Preparation Example 8 above, rosin was used as a modifying agent to obtain a rosin-modified phenol resin solution (modification rate 30%) having an average molecular weight of 1200, a hydroxyl value of 300, and a softening point of 150 ° C.
This resin solution was diluted with toluene to obtain a toluene solution of a rosin-modified phenol resin having a solid concentration of 0.1% by weight.

(10) Preparation Example 10
In accordance with Preparation Example 7, an alkyd resin having an average molecular weight of 2100 and an oil length of 38% and an alkyd resin having an average molecular weight of 2500 and an oil length of 43% were obtained, and a mixture of 50% by weight of these alkyd resins was xylene. To obtain a xylene solution of an alkyd resin having a solid content concentration of 0.1% by weight.

(11) Comparative Preparation Example 1
No post-treatment solution was prepared.

(12) Comparative Preparation Example 2
Based on Preparation Example 1, an acrylic-styrene resin solution (styrene 40 mol%) having an average molecular weight of 60,000, an acid value of 80, and a softening point of 140 ° C. was obtained.
This resin solution was diluted with IPA to obtain an IPA solution of acrylic-styrene resin having a solid content concentration of 0.1% by weight.

(13) Comparative Preparation Example 3
Based on Preparation Example 1, an acrylic-styrene resin solution (styrene 40 mol%) having an average molecular weight of 1500, an acid value of 100, and a softening point of 90 ° C. was obtained.
This resin solution was diluted with IPA to obtain an IPA solution of acrylic-styrene resin having a solid content concentration of 0.1% by weight.

(14) Comparative Preparation Example 4
Based on Preparation Example 4, a maleic acid-styrene resin solution (styrene 55 mol%) having an average molecular weight of 60,000, an acid value of 85, and a softening point of 110 ° C. was obtained.
This resin solution was diluted with IPA to obtain an IPA solution of maleic acid-styrene resin having a solid concentration of 0.1% by weight.

(15) Comparative Preparation Example 5
Based on Preparation Example 4, a maleic acid-styrene resin solution (styrene 55 mol%) having an average molecular weight of 1350, an acid value of 110, and a softening point of 120 ° C. was obtained.
This resin solution was diluted with IPA to obtain an IPA solution of maleic acid-styrene resin having a solid concentration of 0.1% by weight.

(16) Comparative Preparation Example 6
Based on Preparation Example 7, an alkyd resin solution having an average molecular weight of 8000 and an oil length of 63% was obtained.
This resin solution was diluted with xylene to obtain a xylene solution of an alkyd resin having a solid concentration of 0.1% by weight.

(17) Comparative Preparation Example 7
Based on Preparation Example 7, an alkyd resin solution having an average molecular weight of 300 and an oil length of 45% was obtained.
This resin solution was diluted with xylene to obtain a xylene solution of an alkyd resin having a solid concentration of 0.1% by weight.

(18) Comparative Preparation Example 8
Based on Preparation Example 9, a rosin-modified phenol resin solution (modification rate 30%) having an average molecular weight of 3000, a hydroxyl value of 100, and a softening point of 165 ° C. was obtained.
This resin solution was diluted with toluene to obtain a toluene solution of a rosin-modified phenol resin having a solid concentration of 0.1% by weight.

(19) Comparative Preparation Example 9
Based on Preparation Example 9, a phenol resin solution having an average molecular weight of 200, a hydroxyl value of 120, and a softening point of 80 ° C. was obtained.
And this resin solution was diluted with toluene, and the toluene solution of the phenol resin with a solid content concentration of 0.1 weight% was obtained.

Then, after tin-plating to the to-be-plated object, this plating surface was surface-treated with each post-processing liquid obtained by the said preparation example and the comparative preparation example.
<< Example of post-processing the tin plating surface >>
(1) Example 1
(a) Tin plating treatment First, a tin plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 20g / L
Methanesulfonic acid 100g / L
Nonylphenol polyethoxylate (EO15 mol) 8g / L
Hydroquinone 1g / L
Adjustment to pH 1 or less Subsequently, a pure copper plate of 25 mm square and a plate thickness of 0.3 mm was used as an object to be plated, and electroplating was performed using the above tin plating bath to form a tin plating film with a film thickness of 5 μm on the pure copper plate.
(b) Post-treatment of the plating surface The pure copper plate subjected to the above-described plating treatment (a) was immersed in the post-treatment liquid obtained in Preparation Example 1 at 25 ° C. for 10 seconds, and then sufficiently dried.

(2) Examples 2 to 10
On the basis of Example 1 described above, plating treatment and post-treatment were performed under the same conditions as in Example 1 except that the post-treatment liquid was changed from Preparation Example 1 to another preparation example.
The types of post-treatment liquids used in Examples 2 to 10 are as shown in FIG. 1. In Example n, the post-treatment liquids of Preparation Example n (n = 2 to 10) are used (for example, implementation). In Example 2, Preparation Example 2 was used, and in Example 3, Preparation Example 3 was used, respectively (the same applies to Examples 4 to 10 below). The numbers in parentheses in the Example column of FIG. 1 indicate the numbers of the preparation examples (the same applies to FIGS. 2 to 6 which are examples of the following tin alloy).

(3) Comparative Examples 1-9
On the basis of Example 1 described above, plating treatment and post-treatment were performed under the same conditions as in Example 1 except that the post-treatment liquid was changed from Preparation Example 1 to Comparative Preparation Example.
The types of post-treatment liquids used in Comparative Examples 1 to 9 are as shown in FIG. 1, and Comparative Example n used post-treatment liquids of Comparative Preparation Example n (n = each integer of 1 to 9) (for example, Comparative Example 1 used Comparative Preparation Example 1 and Comparative Example 2 used Comparative Preparation Example 2. The following Comparative Examples 3 to 9 were also used). The numbers in parentheses in the comparative example column of FIG. 1 indicate the numbers of comparative preparation examples (the same applies to FIGS. 2 to 6 which are examples of the following tin alloy).
Since Comparative Preparation Example 1 is a blank example in which no post-treatment solution is prepared, in Comparative Example 1, only the tin plating process (a) of Example 1 was applied to the pure copper plate, and the post-process (b) was not performed. .

Subsequently, instead of tin plating, tin-lead alloy plating was applied to the object to be plated, and then the plated surface was surface-treated with each of the post-treatment liquids obtained in the above preparation examples and comparative preparation examples.
<< Example of post-processing the tin-lead alloy plating surface >>
(1) Example 11
(a) Tin-lead alloy plating treatment First, a tin-lead alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 54g / L
Lead methanesulfonate (as Pb2 ⁺ ) 6g / L
Methanesulfonic acid 120g / L
Styrenated phenol polyethoxylate (EO20 mol) 10g / L
Hydroquinone 1g / L
Adjust to pH 1 or less Then, using a pure copper plate of 25 mm square and 0.3 mm thickness as the object to be plated, electroplating is performed using the above tin-lead alloy plating bath to form a tin-lead alloy plating film with a film thickness of 5 μm did.
(b) Post-treatment of plating surface The pure copper plate subjected to the plating treatment of (a) was dipped in the post-treatment liquid obtained in Preparation Example 1 at 25 ° C. for 10 seconds and then sufficiently dried.

(2) Examples 12 to 20
On the basis of Example 11, the plating treatment and the post-treatment were performed under the same conditions as in Example 11 except that the post-treatment liquid was changed from Preparation Example 1 to another preparation example.
The types of post-treatment liquids used in Examples 12 to 20 are as shown in FIG. 2, and in Example n, the post-treatment liquids of Preparation Example (n-10) (n = each integer of 12 to 20) were used. (For example, Preparation Example 2 was used in Example 12 (n = 12) and Preparation Example 3 was used in Example 13 (n = 13). The following Examples 14 to 20 were also used).

(3) Comparative Examples 10-18
On the basis of Example 11, the plating treatment and the post-treatment were performed under the same conditions as in Example 11 except that the post-treatment liquid was changed from Preparation Example 1 to Comparative Preparation Example.
The types of post-treatment liquids used in Comparative Examples 10 to 18 are as shown in FIG. 2, and Comparative Example n uses the post-treatment liquids of Comparative Preparation Example (n-9) (n = each integer of 10 to 18). (For example, Comparative Example 10 (n = 10) used Comparative Preparation Example 1 and Comparative Example 11 (n = 11) used Comparative Preparation Example 2. The same applies to Comparative Examples 12 to 18 below).
Since Comparative Preparation Example 1 is a blank example in which no post-treatment liquid is prepared, in Comparative Example 10, only the tin plating treatment (a) of Example 11 was applied to a pure copper plate, and the post-treatment (b) was not performed. .

Subsequently, after tin-copper alloy plating was performed on the object to be plated, the plated surface was surface-treated with each of the post-treatment liquids obtained in the above preparation examples and comparative preparation examples.
<< Example of post-processing the tin-copper alloy plating surface >>
(1) Example 21
(a) Tin-copper alloy plating treatment First, a tin-copper alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 50g / L
Copper methanesulfonate (as Cu ²⁺ ) 1.5g / L
Methanesulfonic acid 140g / L
β-naphthol polyethoxylate (EO12 mol) 7g / L
Lauryldimethylaminoacetic acid betaine 2g / L
Adjust to pH 1 or lower Then, using a pure copper plate of 25 mm square and 0.3 mm thickness as an object to be plated, electroplating is performed using the above tin-copper alloy plating bath to form a tin-copper alloy plating film with a thickness of 5 μm did.
(b) Post-treatment of plating surface The pure copper plate subjected to the plating treatment of (a) was dipped in the post-treatment liquid obtained in Preparation Example 1 at 25 ° C. for 10 seconds and then sufficiently dried.

(2) Examples 22-30
Plating and post-treatment were performed under the same conditions as in Example 21 except that the post-treatment liquid was changed from Preparation Example 1 to another preparation example based on Example 21.
The types of post-treatment liquids used in Examples 22 to 30 are as shown in FIG. 3, and in Example n, the post-treatment liquids of Preparation Example (n-20) (each integer of n = 22 to 30) were used. (For example, Preparation Example 2 was used in Example 22 (n = 22) and Preparation Example 3 was used in Example 23 (n = 23). The following Examples 24 to 30 were also used).

(3) Comparative Examples 19 to 27
On the basis of Example 21, the plating treatment and the post-treatment were performed under the same conditions as in Example 21 except that the post-treatment liquid was changed from Preparation Example 1 to Comparative Preparation Example.
The types of post-treatment liquids used in Comparative Examples 19 to 27 are as shown in FIG. 3, and Comparative Example n uses the post-treatment liquid of Comparative Preparation Example (n-18) (n = 19 to 27). (For example, Comparative Example 19 (n = 19) used Comparative Preparation Example 1 and Comparative Example 20 (n = 20) used Comparative Preparation Example 2. The following Comparative Examples 21 to 27 were also used).
Since Comparative Preparation Example 1 is a blank example in which no post-treatment solution is prepared, in Comparative Example 19, only the tin plating treatment (a) of Example 21 was applied to a pure copper plate, and the post-treatment (b) was not performed. .

Subsequently, after tin-silver alloy plating was performed on the object to be plated, the plated surface was surface-treated with each of the post-treatment liquids obtained in the preparation examples and the comparative preparation examples.
<< Example of post-processing the tin-silver alloy plating surface >>
(1) Example 31
(a) Tin-silver alloy plating treatment First, a tin-silver alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 20g / L
Silver methanesulfonate (as Ag ⁺ ) 0.5g / L
Methanesulfonic acid 110g / L
Thiourea 5g / L
β-naphthol polyethoxylate (EO12 mol) 7g / L
Adjust to pH 1 or less Then, using a pure copper plate of 25 mm square and 0.3 mm thickness as the object to be plated, electroplating is performed using the above tin-silver alloy plating bath to form a tin-silver alloy plating film with a film thickness of 5 μm did.
(b) Post-treatment of plating surface The pure copper plate subjected to the plating treatment of (a) was dipped in the post-treatment liquid obtained in Preparation Example 1 at 25 ° C. for 10 seconds and then sufficiently dried.

(2) Examples 32 to 40
On the basis of Example 31, the plating treatment and the post-treatment were performed under the same conditions as in Example 31 except that the post-treatment liquid was changed from Preparation Example 1 to another preparation example.
The types of post-treatment liquids used in Examples 32 to 40 are as shown in FIG. 4, and in Example n, the post-treatment liquids of Preparation Example (n-30) (n = 32 to 40 each integer) were used. (For example, Preparation Example 2 was used in Example 32 (n = 32) and Preparation Example 3 was used in Example 33 (n = 33). The following Examples 34 to 40 were also used).

(3) Comparative Examples 28-36
On the basis of Example 31, the plating treatment and the post-treatment were performed under the same conditions as in Example 31 except that the post-treatment liquid was changed from Preparation Example 1 to Comparative Preparation Example.
The types of post-treatment liquids used in Comparative Examples 28 to 36 are as shown in FIG. 4. In Comparative Example n, the post-treatment liquids of Comparative Preparation Example (n-27) (n = 28 to 36) are used. (For example, Comparative Example 28 (n = 28) used Comparative Preparation Example 1 and Comparative Example 29 (n = 29) used Comparative Preparation Example 2. The same applies to Comparative Examples 30 to 36 below).
Since Comparative Preparation Example 1 is a blank example in which no post-treatment solution is prepared, in Comparative Example 28, only the tin plating process (a) of Example 31 was applied to a pure copper plate, and the post-process (b) was not performed. .

Subsequently, after tin-bismuth alloy plating was performed on the object to be plated, the plated surface was surface-treated with each of the post-treatment liquids obtained in the above preparation examples and comparative preparation examples.
<< Example of post-processing the tin-bismuth alloy plating surface >>
(1) Example 41
(a) Tin-bismuth alloy plating treatment First, a tin-bismuth alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 ⁺ ) 9.5g / L
Bismuth methanesulfonate (as Bi ³⁺ ) 0.5g / L
Methanesulfonic acid 100g / L
Bisphenol A polyethoxylate (EO17 mol) 5g / L
Lauryldimethylaminoacetic acid betaine 2g / L
Hydroquinone 1g / L
Adjust to pH 1 or less Then, using a pure copper plate of 25 mm square and 0.3 mm thick as the object to be plated, electroplating is performed using the above tin-bismuth alloy plating bath to form a tin-bismuth alloy plating film with a film thickness of 5 μm did.
(b) Post-treatment of plating surface The pure copper plate subjected to the plating treatment of (a) was dipped in the post-treatment liquid obtained in Preparation Example 1 at 25 ° C. for 10 seconds and then sufficiently dried.

(2) Examples 42-50
On the basis of Example 41, plating treatment and post-treatment were performed under the same conditions as in Example 41 except that the post-treatment liquid was changed from Preparation Example 1 to another preparation example.
The types of post-treatment liquids used in Examples 42 to 50 are as shown in FIG. 5, and in Example n, the post-treatment liquids of Preparation Example (n-40) (n = 42 to 50) were used. (For example, Preparation Example 2 was used in Example 42 (n = 42) and Preparation Example 3 was used in Example 43 (n = 43). The following Examples 44 to 50 were also used).

(3) Comparative Examples 37-45
On the basis of Example 41, plating treatment and post-treatment were performed under the same conditions as in Example 41 except that the post-treatment liquid was changed from Preparation Example 1 to Comparative Preparation Example.
The types of post-treatment liquids used in Comparative Examples 37 to 45 are as shown in FIG. 5. In Comparative Example n, the post-treatment liquids of Comparative Preparation Example (n-36) (n = 37 to 45) are used. (For example, Comparative Example 37 (n = 37) used Comparative Preparation Example 1 and Comparative Example 38 (n = 38) used Comparative Preparation Example 2. The same applies to Comparative Examples 39 to 45 below).
Since Comparative Preparation Example 1 is a blank example in which no post-treatment liquid is prepared, in Comparative Example 37, only the tin plating process (a) of Example 41 was applied to a pure copper plate, and the post-process (b) was not performed. .

Subsequently, after tin-zinc alloy plating was performed on the object to be plated, the plated surface was surface-treated with each of the post-treatment liquids obtained in the above preparation examples and comparative preparation examples.
<< Example of post-processing the tin-zinc alloy plating surface >>
(1) Example 51
(a) Tin-zinc alloy plating treatment First, a tin-zinc gold plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 30g / L
Zinc methanesulfonate (as Zn ²⁺ ) 6g / L
Sulfosuccinic acid 1.5 mol / L
β-naphthol polyethoxylate (EO12 mol) 5g / L
Cetyldimethylbenzylammonium salt 0.05 g / L
Adjustment to pH 2.5 Subsequently, electroplating was performed using the above-described tin-zinc alloy plating bath using a 25 mm square and 0.3 mm thick pure copper plate as an object to be plated, and a tin-zinc alloy plating film having a thickness of 5 μm was formed. Formed.
(b) Post-treatment of plating surface The pure copper plate subjected to the plating treatment of (a) was dipped in the post-treatment liquid obtained in Preparation Example 1 at 25 ° C. for 10 seconds and then sufficiently dried.

(2) Examples 52-60
Based on Example 51 described above, the plating treatment and the post-treatment were performed under the same conditions as in Example 51 except that the post-treatment liquid was changed from Preparation Example 1 to another preparation example.
The types of post-treatment liquids used in Examples 52 to 60 are as shown in FIG. 6, and in Example n, the post-treatment liquids of Preparation Example (n-50) (each integer of n = 52 to 60) were used. (For example, Preparation Example 2 was used in Example 52 (n = 52) and Preparation Example 3 was used in Example 53 (n = 53). The following Examples 54 to 60 were also used).

(3) Comparative Examples 46-54
Based on Example 51 described above, the plating treatment and the post-treatment were performed under the same conditions as in Example 51 except that the post-treatment liquid was changed from Preparation Example 1 to Comparative Preparation Example.
The types of post-treatment liquids used in Comparative Examples 46 to 54 are as shown in FIG. 6. In Comparative Example n, the post-treatment liquids of Comparative Preparation Example (n-45) (n = 46 to 54) are used. (For example, Comparative Example 46 (n = 46) used Comparative Preparation Example 1 and Comparative Example 47 (n = 47) used Comparative Preparation Example 2. The same applies to Comparative Examples 48 to 54 below).
Since Comparative Preparation Example 1 is a blank example in which no post-treatment solution is prepared, in Comparative Example 46, only the tin plating process (a) of Example 51 was applied to the pure copper plate, and the post-process (b) was not performed. .

Then, the solder wettability of the plating surface of the pure copper plate which performed each post-processing method of the said Examples 1-60 and Comparative Examples 1-54 was investigated.
<Example of solder wettability test on tin and tin alloy plating surface>
In the following solder wettability test, an accelerated test was added, and the plated surface subjected to post-treatment was placed in a harsh atmosphere, and the solder wettability of the tin plated surface and various tin alloy plated surfaces was evaluated.
That is, the plated surfaces of the pure copper plates subjected to the post-treatment of Examples 1 to 60 and Comparative Examples 1 to 54 were subjected to a solder wettability test under the following conditions, and the zero cross time (seconds) was measured.
(A) Acceleration test Based on a pressure cooker, the temperature was 105 ° C., the relative humidity was 100%, and the time was 4 hours.
(B) Wetting test conditions Solder: Eutectic solder with tin / lead = 63/37 Bath temperature: 230 ° C
Immersion depth: 10mm
Immersion time: 10 seconds Immersion speed: 25 mm / second Flux: 25% rosin flux Measurement method: Meniscograph method

(1) Evaluation of tin-plated surface Fig. 1 shows the test results of the tin-plated surface.
In Examples 1 to 10 in which the surface of the tin plating was post-treated, compared to Comparative Example 1 in which the post-treatment was not performed, the zero cross time was clearly short in the wetting time after the acceleration test, and the post-treatment was solder wetting after the acceleration test. It was confirmed that it contributed to the prevention of deterioration of the property. Regardless of whether the post-treatment resin is an acrylic resin, a maleic acid resin, an alkyd resin, or a phenol resin, it is the same evaluation in that the solder wettability can be improved, and the form of the post-treatment liquid is an alcohol solution. It has been found that either a hydroalcoholic solution or an organic solvent solution of toluene or xylene functions effectively.
Moreover, if Examples 1-10 are relatively evaluated, in Examples 1-3, Examples 5-7 and 10 in which the post-processing resin is an acrylic resin and an alkyd resin, the effect of preventing deterioration of solder wettability with time is large. In Example 4 and Examples 8-9 using a maleic acid resin and a phenol resin, it was a level according to an acrylic resin and an alkyd resin.

On the other hand, Comparative Example 2 in which the average molecular weight of the acrylic resin is 60,000 exceeding the upper limit of the specific range of the present invention, or Comparative Example 3 in which 1500 is less than the lower limit of the same range is used in Example 1 using the acrylic resin. In contrast to Examples 3 to 3, Examples 1 to 3 exhibit excellent solder wettability, while Comparative Examples 2 to 3 have a greater regression than these Examples (although improved over Comparative Example 1). Therefore, even if the average molecular weight of the acrylic resin is too large or too small, it does not contribute to the prevention of solder wettability over time, and the need to optimize the average molecular weight of the acrylic resin can be confirmed. It was.
Similarly, (a) Example 4 using a maleic acid resin having an average molecular weight within an appropriate range is compared with Comparative Examples 4 to 5 using a maleic resin deviating from the same range to the upper and lower limits. (B) Examples 5 to 7 and 10 using alkyd resins having an average molecular weight in an appropriate range are compared with Comparative Examples 6 to 7 using alkyd resins deviating from the same range to the upper and lower limits, or (C) Examples 8 to 9 using a phenol resin having an average molecular weight in an appropriate range are compared with Comparative Examples 8 to 9 using an alkyd resin deviating from the same range to the upper and lower limits. In the example, the deterioration of the solder wettability with time could not be prevented, so that it was recognized that the importance of limiting the average molecular weight of each resin within an appropriate range for maintaining the solder wettability.

(2) Evaluation of various tin alloy plated surfaces FIGS. 2 to 6 show test results of various tin alloy plated surfaces.
Similar to the above tin plating surface, acrylic resin, maleic acid resin, alkyd resin, phenol resin for the plating surfaces of tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-bismuth alloy and tin-zinc alloy In the examples after-treatment with a specific resin selected from the above, compared with the comparative example in which no post-treatment was performed, the zero cross time after the acceleration test was clearly shorter, and the post-treatment deteriorated the solder wettability after the acceleration test. It was confirmed that it contributed to prevention. In this case, regardless of whether the resin for post-treatment uses an acrylic resin or other specific resin, and the form of the post-treatment liquid is an alcohol solution, a hydrous alcohol solution, or an organic solvent liquid, both are solders. It was the same evaluation in the point which can maintain wettability.
Furthermore, even if a specific post-treatment resin such as an acrylic resin or an alkyd resin is used, in the comparative examples in which the average molecular weight of each resin is out of the appropriate range, it is impossible to prevent deterioration of solder wettability with time. On the tin alloy plating surface, similar to the above tin plating surface, it was confirmed that it was necessary to limit the average molecular weight of the post-treatment resin to each appropriate range in order to maintain the solder wettability.

It is a graph which shows the test result of Examples 1-10 and Comparative Examples 1-9 about the post-process with respect to a tin plating surface. It is a graph which shows the test result of Examples 11-20 and Comparative Examples 10-18 about the post-process with respect to a tin-lead alloy plating surface. It is a graph which shows the test result of Examples 21-30 and Comparative Examples 19-27 about the post-process with respect to a tin- copper alloy plating surface. It is a graph which shows the test result of Examples 31-40 and Comparative Examples 28-36 about the post-process with respect to a tin- silver alloy plating surface. It is a graph which shows the test result of Examples 41-50 and Comparative Examples 37-45 about the post-process with respect to a tin-bismuth alloy plating surface. It is a graph which shows the test result of Examples 51-60 and Comparative Examples 46-54 about the post-process with respect to a tin- zinc alloy plating surface.

Claims (6)

After forming a tin or tin alloy plating film on the object to be plated, a liquid for post-processing the plating surface,
Containing at least one kind of post-treatment resin selected from the following (A) to (C):
(A) Acrylic resin or maleic resin having an average molecular weight of 2000 to 50000
(B) Alkyd resin having an average molecular weight of 500 to 5,000
(C) A phenol resin having an average molecular weight of 300 to 2,000, and a post-treatment liquid for tin or tin alloy plating surface characterized by not containing chlorine and chromium.   The acid value of the acrylic resin is 100 to 500, the softening point is 80 to 200 ° C, the acid value of the maleic acid resin is 100 to 300, the softening point is 80 to 200 ° C, and the oil length of the alkyd resin is 35 to 55 2. The post-treatment liquid for tin or tin alloy plating surface according to claim 1, wherein the phenolic resin has a hydroxyl group equivalent of 130 to 1000 and a softening point of 90 to 200 ° C. 3.   The post-treatment liquid for a tin or tin alloy plating surface according to claim 1 or 2, wherein the post-treatment resin is reacted with ammonia or a low boiling point amine to form an ammonium salt or an amine salt.   The tin alloy is an alloy of tin and at least one metal selected from the group consisting of bismuth, copper, zinc, nickel, silver, gold, indium, antimony, lead, cobalt, thallium, and gallium. The tin or tin alloy plating surface post-treatment liquid according to any one of claims 1 to 3.   After forming a tin or tin alloy plating film on an object to be plated, the plating surface is brought into contact with the post-treatment liquid according to any one of claims 1 to 4, wherein the tin or tin alloy plating surface Post-processing method.   6. Electronic parts such as semiconductor devices, printed circuit boards, flexible printed circuit boards, film carriers, connectors, switches, resistors, variable resistors, capacitors, filters, inductors, thermistors, crystal resonators, lead wires, etc. subjected to a post-processing method. .

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