JP2007262394A - Surface-treating agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-treating agent which can inhibit the formation of coating films on a different kind of metal and can reduce environmental loads. <P>SOLUTION: This surface-treating agent for treating the surface of copper or a copper alloy is characterized by comprising an imidazole compound and a sugar alcohol. The surface-treating agent can inhibit the formation of coating films on a different kind of metal, because copper ion eluted in the surface-treating agent is bound to the sugar alcohol. Furthermore, waste liquids can easily be treated, and environmental loads can be reduced, because the sugar alcohol is used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface treatment agent for copper or copper alloy.

  Conventionally, an OSP (water-soluble) containing an imidazole compound such as benzimidazole as a surface treatment agent for improving the rust prevention and solderability of circuit wiring made of copper or a copper alloy (hereinafter also simply referred to as “copper”). Preflux) is known (see, for example, Patent Documents 1 to 4).

  On the other hand, in printed wiring boards, metals other than copper, such as gold, silver, aluminum, tin, and solder (hereinafter also referred to as “foreign metals”) may coexist on the copper wiring. When a substrate in which such a different metal coexists is treated with a water-soluble preflux containing the imidazole compound as described above, a film may be formed on the different metal to cause a problem such as discoloration.

  The reason why a film is formed on a dissimilar metal is that when treating with the above-mentioned water-soluble preflux, copper ions eluted from the copper surface into the water-soluble preflux liquid adhere to the dissimilar metal as oxides or hydroxides. It is considered that a film is formed by bonding copper and imidazole compound on the adhered dissimilar metal.

In order to solve the above problem, a technique for chelating the copper ions eluted from the substrate into the surface treatment agent to prevent the copper ions from adhering to the different metal has been proposed (for example, see Patent Documents 5 to 7). .
JP-A-7-54169 JP-A-5-237688 JP-A-5-163585 Japanese Patent Laid-Open No. 11-177218 JP-A-52-72342 JP-A-6-81161 Japanese Patent Laid-Open No. 9-291372

  However, the methods described in Patent Documents 5 to 7 use a chelating agent that complicates the treatment method at the time of waste liquid treatment, which may increase the environmental load. Moreover, since the chelating agent described in Patent Documents 5 to 7 inhibits the formation of a film on copper, the methods described in Patent Documents 5 to 7 may reduce solderability.

  The present invention has been made in view of such circumstances, and provides a surface treatment agent that can suppress the formation of a film on a dissimilar metal without inhibiting the formation of a film on copper and can reduce the environmental burden.

  The surface treatment agent of the present invention is a copper or copper alloy surface treatment agent, and contains an imidazole compound and a sugar alcohol.

  According to the surface treatment agent of the present invention, since the copper ions eluted in the surface treatment agent and the sugar alcohol bind to each other, it is possible to suppress the film formation on the dissimilar metal without inhibiting the film formation on the copper. Moreover, since sugar alcohol is used, waste liquid processing becomes easy and an environmental load can be reduced.

  The surface treating agent of the present invention is used for the purpose of forming a film on the surface of copper for forming wiring, for example, for rust prevention and solderability improvement. The said surface treating agent contains the imidazole compound used as the main component of the membrane | film | coat formed, and the sugar alcohol couple | bonded with the copper ion eluted in the said surface treating agent. As a result, film formation on different metals can be suppressed, and since sugar alcohol is used, waste liquid treatment becomes easier than conventional surface treatment agents using chelating agents, and the environmental burden can be reduced. Moreover, when the surface treatment agent is used as a water-soluble preflux, a film having high heat resistance can be formed without lowering the solderability even after a high temperature treatment step such as reflow.

  The surface treatment agent can be prepared, for example, by dissolving an imidazole compound and a sugar alcohol in a solvent. As the solvent, water such as ion-exchanged water, pure water or ultrapure water, acids such as organic acids and inorganic acids, water-soluble organic solvents, and the like can be used. When an acid or a water-soluble organic solvent is used as the solvent, dissolution of the imidazole compound can be promoted.

  Although the imidazole compound is not particularly limited, for example, 2-propylbenzimidazole, 2-cyclohexylbenzimidazole, 2-phenylbenzimidazole, 2-benzylbenzimidazole, 2- (3-phenylpropyl) -5-methylbenzimidazole, Benzimidazole compounds such as 2- (mercaptomethyl) benzimidazole, 2- (1-naphthylmethyl) benzimidazole, 2- (5′-phenyl) pentylbenzimidazole, 2-phenylethylbenzimidazole, 2,4-diphenyl -5-methylimidazole, 2-pentylimidazole, 2-undecyl-4-methylimidazole, 2,4-dimethylimidazole, 2,4-diphenylimidazole, 2,4,5-triphenylimidazole, 2 Benzyl imidazole, 2-benzyl-4-imidazole compounds such methylimidazole can be used. Moreover, the surface treating agent of this invention may contain 2 or more types of these imidazole compounds.

  The concentration of the imidazole compound in the surface treatment agent is preferably 0.01 to 5% by mass, more preferably 0.05 to 1% by mass. When the concentration of the imidazole compound is less than 0.01% by mass, a film may not be formed. On the other hand, when the concentration of the imidazole compound exceeds 5% by mass, a precipitate of the imidazole compound may be generated.

  The sugar alcohol is not particularly limited, and monosaccharide alcohols such as mannitol, sorbitol, xylitol, erythritol, maltitol, and lactitol, disaccharide alcohols such as sucrose, polysaccharide alcohols such as oligosaccharide alcohol, and the like can be used. Among these, mannitol, sorbitol, and xylitol are preferable because they are inexpensive and easily available. The surface treatment agent of the present invention may contain two or more kinds of these sugar alcohols.

  The concentration of the sugar alcohol in the surface treatment agent is preferably 0.01 to 7% by mass, more preferably 0.05 to 4% by mass, and most preferably 0.1 to 1% by mass. When the concentration of the sugar alcohol is less than 0.01% by mass, the effect of suppressing film formation on the dissimilar metal may be reduced. On the other hand, when the concentration of the sugar alcohol exceeds 7% by mass, no further effect can be expected, which may be uneconomical.

  When the surface treatment agent of the present invention contains an organic acid, specific examples of the organic acid that can be used include formic acid, acetic acid, propionic acid, glycolic acid, n-butyric acid, isobutyric acid, acrylic acid, crotonic acid, isocrotonic acid, and shu Acid, malonic acid, succinic acid, adipic acid, maleic acid, acetylenedicarboxylic acid, monochloroacetic acid, trichloroacetic acid, monobromoacetic acid, lactic acid, oxybutyric acid, glyceric acid, tartaric acid, malic acid, citric acid, enanthic acid, caproic acid, What mixed 2 or more types among these can be illustrated. The concentration of the organic acid in the surface treatment agent is preferably 1 to 80% by mass, more preferably 1.5 to 45% by mass, and most preferably 3 to 30% by mass. When the concentration of the organic acid is less than 1% by mass, a precipitate of an imidazole compound may be generated. On the other hand, when the concentration of the organic acid exceeds 80% by mass, it is difficult to form a film.

  When the surface treating agent of the present invention contains an inorganic acid, specific examples of the inorganic acid that can be used include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and a mixture of two or more thereof. The density | concentration of the inorganic acid in the said surface treating agent becomes like this. Preferably it is 1-80 mass%, More preferably, it is 1.5-30 mass%, Most preferably, it is 3-15 mass%. When the concentration of the inorganic acid is less than 1% by mass, a precipitate of the imidazole compound may be generated. On the other hand, when the concentration of the inorganic acid exceeds 80% by mass, it is difficult to form a film.

  When the surface treating agent of the present invention contains a water-soluble organic solvent, specific examples of the water-soluble organic solvent that can be used include methanol, ethanol, 2-propanol, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether. The concentration of the water-soluble organic solvent in the surface treatment agent is preferably 1 to 80% by mass, more preferably 1.5 to 30% by mass, and most preferably 3 to 15% by mass. When the concentration of the water-soluble organic solvent is less than 1% by mass, a precipitate of an imidazole compound may be generated. On the other hand, when the concentration of the water-soluble organic solvent exceeds 80% by mass, it is difficult to form a film.

  The usage method of the surface treating agent of this invention is not specifically limited, For example, it can use by the immersion method, the spray method, etc. When using the immersion method, for example, the immersion time may be about 15 to 120 seconds. In addition to the above-exemplified components, additives such as a film forming aid and a dissolution stabilizer may be blended with the surface treatment agent of the present invention as necessary. In addition, the use temperature of the said surface treating agent is the range of 25-35 degreeC normally.

  When the surface treatment agent of the present invention is used with an apparatus, for example, all components of the surface treatment agent may be prepared to have a predetermined composition and then supplied to the apparatus, or each component may be individually supplied. The components may be supplied to the apparatus and the components may be mixed in the apparatus so as to have a predetermined composition. Further, when supplying each component of the surface treatment agent to the apparatus, the concentration of each component is not particularly limited. For example, each component having a high concentration is supplied to the apparatus, and acid or water is used in the apparatus. May be diluted to a predetermined concentration.

  In addition, copper ions may be added to the surface treatment agent for forming a rust preventive film on copper for the purpose of easily forming a film. When copper ions are added, a film is also formed on the dissimilar metal, so copper ions cannot be added, and there is a possibility that the film is difficult to be formed on the copper surface. In the surface treatment agent of the present invention, the film-forming property on the copper surface is not lowered even if copper ions are not added due to the action of the sugar alcohol.

  Examples of the surface treatment agent of the present invention will be described below together with comparative examples. In addition, this invention is not limited to the following Example.

Experiment 1 (Evaluation of the amount of film formed on different metals)
First, 0.1% by mass of 2- (1-naphthylmethyl) benzimidazole, 5.25% by mass of formic acid, and xylitol at the concentrations shown in Table 1 were added to ion-exchanged water, and the surfaces of Examples 1-12. A treating agent was prepared. Further, as Comparative Example 1, a surface treatment agent prepared in the same manner as in Examples 1 to 12 except that xylitol was not added was prepared.

  Next, a double-sided copper-clad laminate (4 cm x 4 cm) with 18 μm thick copper foil attached to both sides of a glass epoxy substrate (GEA-67N manufactured by Hitachi Chemical Co., Ltd., thickness: 1.6 mm) was prepared. A Ni-plated film having a thickness of 0.5 μm was formed on the copper foil, and a gold-plated film having a thickness of 0.05 μm was further formed on the Ni-plated film to prepare a material to be processed. Then, after immersing this to-be-processed material one by one in each of the surface treating agent of Examples 1-12 and Comparative Example 1, it washed with water and dried. At this time, each of the surface treatment agents was performed in two ways: when copper acetate was added at a concentration of 30 mg / L at a copper ion concentration and when not added. The temperature of the surface treatment agent was 30 ° C. for all. Next, the treated material after drying was immersed in a mixed liquid of 35% by mass hydrochloric acid and methanol (mass ratio hydrochloric acid: methanol = 0.5: 99.5) for 5 minutes, and the film component adhered on the gold Was dissolved in the above mixture. And the said liquid mixture with which the film | membrane component melt | dissolved was sampled, and the light absorbency of the absorption peak (277 nm) of 2- (1-naphthylmethyl) benzimidazole was measured with the ultraviolet visible absorption spectrophotometer. And the light absorbency when not adding the copper ion of the comparative example 1 was set to 1, the relative value of the light absorbency when another surface treating agent was used was calculated, and the film amount on gold | metal | money was evaluated from the value. The results are shown in Table 1.

  In Examples 1 to 12, there is no appearance defect by visual observation, and as shown in Table 1, the absorbance is smaller than that of Comparative Example 1 (that is, the amount of film on gold is small), and the film formation on gold is suppressed. I understood that I could do it. In particular, in Examples 3 to 10 in which the concentration of xylitol was 0.05 to 4% by mass, the appearance by visual observation was good, and even when copper ion was added at 30 mg / L, film formation on gold was effectively performed. I was able to suppress it.

Experiment 2 (Relationship between the concentration of copper ions in the surface treatment agent and the coating amount)
First, 0.3% by mass of 2-methylbenzimidazole, 4.5% by mass of acetic acid, and 0.5% by mass of D-sorbitol were added to ion-exchanged water, and the copper ion concentrations shown in Table 2 were further added. Copper acetate was added so that the surface treatment agents of Examples 13 to 20 were prepared. Moreover, the surface treating agent of Comparative Examples 2-9 prepared similarly to Examples 13-20, respectively, except not adding D-sorbitol as a comparative example was prepared. And about each of Examples 13-20 and Comparative Examples 2-9, the to-be-processed material was processed like the said experiment 1, and the film amount on gold | metal | money was evaluated by the method similar to the said experiment 1. The results are shown in Table 2.

  As shown in Table 2, Examples 13 to 20 have a smaller amount of film on the gold even when the copper ion concentration is higher than those of the corresponding Comparative Examples 2 to 9, and suppress the film formation on the gold. I understood that I could do it.

  From the above results, it can be seen that according to the surface treatment agent of the present invention, film formation on different metals can be suppressed. Further, as shown in Table 3 in which the amount of the film on gold was similarly evaluated by changing the imidazole compound and in Table 4 in which the amount of the film on gold was similarly evaluated by changing the sugar alcohol, the surface treatment of the present invention was performed. The agent can exert the above effect regardless of the type of imidazole compound or the type of sugar alcohol. In Table 3, the absorbance was measured when copper acetate was added at a concentration of 30 mg / L at a copper ion concentration, and the amount of film was evaluated using a blank (absorbance: 1) when no sugar alcohol was added. Moreover, in Table 4, about the type | system | group which uses 0.1 mass% 2- (5'-phenyl) pentyl benzimidazole and 4.5 mass% acetic acid, the kind of sugar alcohol was changed and the film amount was evaluated. did.

Experiment 3 (Confirmation of solderability improvement effect)
First, 0.3% by mass of 2- (5′-phenyl) pentylbenzimidazole, 4.5% by mass of acetic acid, and a sugar alcohol shown in Table 5 were added to ion-exchanged water, and Examples 35 to 44 were performed. A surface treatment agent was prepared. Further, as Comparative Example 11, a surface treatment agent prepared in the same manner as in Examples 35 to 44 except that no sugar alcohol was added was prepared.

  Next, a double-sided copper-clad laminate (7.8 cm × 4.8 cm) in which a 18 μm thick copper foil was pasted on both sides of a glass epoxy substrate (GEA-67N, manufactured by Hitachi Chemical Co., Ltd., thickness: 1.6 mm). Prepared, 160 through-holes with a diameter of 0.8 mm were formed in this, and the to-be-processed material was produced. Then, after immersing this to-be-processed material in Meckbright CB-801 (micro etching agent by Meck Co., Ltd.), etching the copper foil surface only 1 micrometer, and washing with water, Examples 35-44 and Comparative Example 11 One sheet was immersed in each surface treatment agent for 60 seconds, washed with water and dried. The temperature of the surface treatment agent was 30 ° C. for all. Next, the reflow process was performed 1 to 4 times for each of the processed materials after drying. A hot air circulation type reflow furnace was used for the reflow treatment, and for each reflow treatment, the surface temperature of the material to be treated was heated at a temperature of 240 to 245 ° C. for 40 seconds. Subsequently, the material to be treated was post-flux treated by spraying. As a post-flux agent, AGF-880 manufactured by Asahi Chemical Research Co., Ltd. was used. Thereafter, flow processing was performed. In the flow treatment, first, as a preheating treatment, the surface temperature of the material to be treated was heated for 80 seconds at a temperature of 100 ° C., and then subjected to a double wave treatment under the condition of a solder temperature of 255 ° C. At this time, the used solder had a mass ratio (Sn: Ag: Cu) of 96.5: 3: 0.5. In the double wave treatment in this experiment, the treatment material and the solder are brought into contact with each other for 2.5 seconds, and then the treatment material and the solder are again brought into contact with each other for 3 seconds at an interval of 2.5 seconds. went. And the soldering defect rate was confirmed about each of the said to-be-processed material. The results are shown in Table 5. The soldering failure rate in Table 5 is the ratio of through holes where soldering failure occurred out of 160 through holes. In addition, the soldering defect in this experiment means the case where it can be confirmed by visual observation that the solder is not completely filled in the through hole.

  As shown in Table 5, in Examples 35 to 44, the soldering failure rate could be reduced as compared with Comparative Example 11. From the above results, it can be seen that the surface treatment agent of the present invention can form a film having high heat resistance.

Experiment 4 (Confirmation of solder wettability improvement effect)
First, Examples 45-54 were prepared by adding 0.3% by mass of 2- (5′-phenyl) pentylbenzimidazole, 4.5% by mass of acetic acid, and the sugar alcohol shown in Table 6 to ion-exchanged water. A surface treatment agent was prepared. Further, as Comparative Example 12, a surface treatment agent prepared in the same manner as in Examples 45 to 54 except that no sugar alcohol was added was prepared.

  Next, a single-sided copper-clad laminate in which a copper foil having a thickness of 18 μm was pasted on one side of a glass epoxy substrate (GEA-67N, manufactured by Hitachi Chemical Co., Ltd., thickness: 1.6 mm) was prepared. Forty pieces of 8 mm rectangular conductor patterns were formed to produce a material to be treated. Then, after immersing this to-be-processed material in Meckbright CB-801 (micro etching agent by MEC Co., Ltd.), etching the copper foil surface only 1 micrometer, and washing with water, Examples 45-54 and Comparative Example 12 One sheet was immersed in each surface treatment agent for 60 seconds, washed with water and dried. The temperature of the surface treatment agent was 30 ° C. for all. Thereafter, a solder paste (TAS650 S10 / 011 / M9.5 manufactured by Solder Coat Co., Ltd.) was printed on the central portion of the conductor pattern. At this time, the printing pattern was circular. Each printed pattern had a diameter of 0.4 mm and a thickness of 100 μm. After printing, using the same reflow furnace as in Experiment 3, the surface temperature of the material to be treated was heated for 40 seconds at a temperature of 225 to 230 ° C. And about the area | region (40 places) of the solder expanded by this reflow process, the length of the longest diameter was measured with the microscope, respectively, and the average value was computed. The results are shown in Table 6.

  As shown in Table 6, the solder wettability was improved in any of Examples 45 to 54 as compared with Comparative Example 12.

  The surface treatment agent of the present invention is useful for a water-soluble preflux, a rust prevention treatment agent, and the like.

Claims (3)

A surface treatment agent for copper or copper alloy,
A surface treatment agent comprising an imidazole compound and a sugar alcohol.   The surface treatment agent according to claim 1, wherein the sugar alcohol is contained in a range of 0.01 to 7 mass%.   The surface treatment agent according to claim 1 or 2, wherein the sugar alcohol is at least one selected from mannitol, sorbitol, and xylitol.