TW201211323A - Cyanide based electrolytic gold plating solution and plating method using same - Google Patents

Abstract

Disclosed is a cyanide based electrolytic gold plating solution characterized by containing a dicyanoaurate (I) alkali salt or dicyanoaurate (I) ammonium salt such that the gold concentration is 1.0 - 5.0 g/L, crystal adjuster, conductive salt, buffer and deposition accelerator formed from one of either a sulfite alkali salt and sulfite ammonium salt such that sulfite ions amount to 0.1 mg/L - 18 g/L.

Description

201211323 VI. EMBODIMENT OF THE INVENTION [Technical Field] The present invention relates to a gold-clad electrolytic shovel gold bath and a plating method using the same, in which a gold-plated film is formed on a printed wiring board such as a BGA (Ball Grid Array) wiring board, or Suitable for use in electronic industrial parts such as 1C packages, germanium or compound wafers. [Prior Art] A gold-plated film formed by using a cyanide electrolytic gold plating bath is widely used for, for example, a printed wiring board and other precision electronic machine parts such as a 1C package, an LSI package, or an LC drive 1C. The gold film used for these precision electronic machine parts is required to have high wire bonding properties, solder joint properties, and heat resistance. The smoothness and gold purity of the gold-plated coating are important factors influencing these characteristics. In order to form a gold-plated film having improved properties, a crystal modifier such as ruthenium or lead is used (Patent Document 1 - 3). The gold concentration in the cyanide electrolytic gold plating bath is generally 8 to 10 g/L. As long as the gold concentration is within this range, a cathode current efficiency of about 95% can be obtained. However, if the gold concentration in the plating bath is lowered to 4 g/L or less, the cathode current efficiency is remarkably lowered, and the productivity is deteriorated. In addition, because of the decrease in cathode current efficiency, side reactions occur with the generation of hydrogen. Affected by this, electroplating scorching may occur, or abnormal deposition of a gold-plated film mainly caused by resist stripping may occur. As a result, a short circuit of the circuit pattern, peeling of the electrodeposited film, and a failure in the subsequent step may occur. Reducing the gold concentration in the mineral bath is effective in reducing the operating cost of electroplating to -5 - 201211323. However, if the concentration of gold in the plating bath is lowered too low, the cathode current efficiency is lowered, and the above problem occurs. In the conventional cyanide electrolytic gold plating bath, when the cathode current density is in the range of 0 gt; 1 to 0·3 A/dm 2 , the plating uniformity is high. The reason for this is because in actual operation, suitable plating can be performed in the range of a cathode current density of 0.1 to 0.3 A/dm2. However, in the case where the gold concentration in the plating bath is less than 5 g/L, in the range of the cathode current density of 〇.1 to 5.5 A/dm2, particularly in the range of 0.1 to 0.3 A/dm2, Electroplating is performed with over 90% cathode current efficiency. [PRIOR ART DOCUMENT] [Patent Document 1] Japanese Unexamined Patent Publication No. Hei. No. Hei. No. Hei. Problem to be Solved The problem to be solved by the present invention is to provide a cyanide electrolytic gold plating bath and a plating method using the same, even if the gold concentration in the plating bath is 5 g/L or less, the cathode current density is In the range of 0.01 to 1.5 A/dm 2 ', a smooth gold-plated film can be formed with high cathode current efficiency. A further object of the present invention is to provide a cyanide electrolytic gold plating bath and a plating method using the same, which can form a gold plating film having high plating thickness uniformity and high wire bonding property or solder ball bonding property. 8 -6- 201211323 [Method for Solving the Problem] The results of the review by the inventors of the present invention were found to be trace amounts by using an alkali metal salt of dicyandiamide (I) or ammonium dicyanate (I). a crystallizing agent, a conductive salt, a buffering agent, and a gold plating bath having a pH of 3.5 to 8.5, and blending: (1) a precipitation accelerator containing at least one of an alkali metal sulfite and an ammonium sulfite, or (2) The precipitation accelerator and ethylenediaminetetraacetate can solve the above problems. In addition, it has been found that the gold plating bath has a high cathode current efficiency and a high shovel thickness in the range of a cathode current density of 〇. 〇1 to 1.5 A/dm2, and a smooth gold-plated film is formed on the surface of the film. Further, it was found that the gold ore film has the same wire bonding property and solder ball bonding property as the gold plating film formed by the conventional cyanide electrolytic gold plating bath. The inventors have found the above points to achieve the completion of the present invention. The present invention which can solve the above problems is as follows. [1] A cyanide electrolytic shovel gold bath characterized by comprising: dicyandiamide (I) alkali metal salt or dicyandiamide (I) ammonium salt, which is 1·0 to 5. Og in terms of gold concentration. /L, a precipitation promoter composed of any one or more of a crystal modifier, a conductive salt, a buffer, an alkali metal sulfite, and an ammonium sulfite, and is 0.1 mg/L to 18 g/based on sulfite ions. L. The alkali metal sulfite or ammonium sulfite contained in the gold plating bath is adsorbed on the plating surface of the cathode by 201211323, and acts as a precipitation promoter to increase the activity point of the gold-donor reduction precipitation reaction. As a result, it is considered that the cathode limit current density is increased, and the high cathode current efficiency can be maintained even when the gold concentration in the plating bath is low. On the other hand, when an alkali metal sulfite or ammonium sulfite is added in an amount of more than > 18 g/L, it is considered that the protons are self-administered to function as a precipitation inhibitor, and therefore it is necessary to pay attention. [2] A cyanide electrolytic gold bath characterized by: dicyandiamide (I) alkali metal salt or di-nuclear acid (I) ammonium salt, 1.0 to 5.0 g/L in terms of gold concentration a crystallization modifier, a conductive salt, a buffering agent, a precipitation accelerator composed of any one or more of an alkali metal sulfite and an ammonium sulfite, and a sulfite ion of l.1 mg/L to 18 g/L, With ethylenediaminetetraacetic acid. [3] The cyanide electrolytic gold plating bath as described in [2], wherein the concentration of ethylenediaminetetraacetic acid is 〇.lmg/L to 20g/L. [4] The cyanide electrolytic gold plating bath according to [2], wherein the conductive salt is one or more selected from the group consisting of citrate and formic acid salt, and the concentration of the conductive salt is It is 100~250g/L. [5] The electrolytic gold plating bath according to [2], wherein the crystal modifier is composed of a ruthenium compound or a lead compound, and the concentration of the crystallization modifier is 0.1 to 20 mg/L in terms of bismuth or lead. [8] The electrolytic gold plating bath according to [1] or [2], wherein the buffering agent is one or more selected from the group consisting of phosphoric acid, boric acid, citric acid, and the like. The concentration of the buffer is 1 to 300 g/L. [7] A method of electroplating a printed wiring board, characterized in that the cyanide electrolytic gold plating bath according to [1] or [2] is used, and the cathode current density is 0.05 to 0.5 A/dm2, and the plating bath is ρΗ3·5. ~8.5, plating bath temperature 55~70 °C for electroplating. [Effects of the Invention] The cyanide electrolytic gold plating bath of the present invention (hereinafter also referred to as "the present gold plating bath") has a high cathode current efficiency even at a low gold concentration. In addition, the gold plating bath can form a uniform gold film which is uniform and dense in the object to be plated and has a good appearance. This gold-plated bath even has excellent liquid stability and liquid life. Even if the gold concentration is below 3 g/L, the gold plating bath will not decrease the cathode current efficiency. Therefore, side reactions do not occur with the generation of hydrogen. As a result, the gold plating film which is not caused by the electroplating or the peeling of the resist is not precipitated abnormally. The gold plating bath can form a plating film having a good appearance in a region where the current density is 〇.〇5 to 0.5 A/dm2. The gold plating bath can still be used in the case where the cathode current density becomes small due to the limitation of the substrate or the plating apparatus. When the gold plating bath is used at a high current density, the plating time can be shortened to improve productivity. By the gold plating film formed by the gold plating bath, the plating thickness can be improved, and the wire bonding property and the solder ball bonding property equivalent to the gold plating 201211323 film formed by the conventional cyanide electrolytic gold plating bath can be obtained. The gold-plated film formed using the present gold plating bath is low in stress and low in hardness, and thus does not erode the photoresist or the underlying layer. [Embodiment] Hereinafter, the present invention will be described in detail. The gold plating bath is characterized in that: dicyandiamide (I) acid alkali metal salt or dicyandiamide (I) ammonium salt is used as a gold source, and contains a trace amount of a crystal modifier, a conductive salt, and a buffer, and the pH is In the gold plating bath of 3.5 to 8.5, (1) blending one or more precipitation accelerators containing an alkali metal sulfite and an ammonium sulfite salt, or (2) adding a blending agent in addition to the above-mentioned precipitation accelerator Ethylenediamine tetraacetate. As the gold source to be blended in the gold plating bath, an alkali metal salt or an ammonium salt of dicyandiamide (I) acid can be cited. The alkali metal salt may, for example, be an alkali metal salt such as Na or K or an alkaline earth metal salt such as Ca. The blending amount of the dicyandiamide (I) acid salt in the gold plating bath is not particularly limited, and the gold content is preferably from 1 〇 to 5.0 g/L, and more preferably from 2.0 to 4.0 g/L. The gold concentration of 2.0 to 40 g/L is most excellent in economical operation, so it is suitable. If the gold content is less than 〇g/L, plating is performed at a high cathode current density, and electroplating scorching occurs, and the smoothness of the plating surface is likely to deteriorate. Examples of the crystal modifier to be blended in the gold plating bath include water-soluble salts (for example, sulfates, nitrates, and organic acid salts) such as cesium, 8 -10-201211323, and lead. The amount of the crystal modifier to be blended in the gold plating bath is 0.1 to 20 mg/L in terms of each metal. In particular, when the gold concentration in the plating bath is 4 g/L or less, in order to obtain high cathode current efficiency, the blending amount of the crystal modifier is preferably 0.1 to 5 mg/L for each metal. The conductive salt to be blended in the gold plating bath may, for example, be a mineral acid salt or an organic acid salt such as a phosphate, a sulfate, a borate, a citrate, an oxalate or a citrate. These two or more types may also be used in combination. The blending amount of the conductive salt in the gold bath of the present invention can appropriately set the range in which the solute in the plating bath does not cause salt precipitation due to supersaturation. The blending amount of the conductive salt is usually from 50 to 250 g/L, preferably from 100 to 150 g/L. When the blending amount of the conductive salt is less than 5 Og/L, the conductivity of the plating bath is low, the ability to thicken the electric ore is deteriorated, or the components constituting the plating bath are decomposed. When the blending amount of the conductive salt exceeds 25 Og/L, salt precipitation occurs at room temperature, the boundary current density is lowered, and plating is burnt. The buffering agent to be blended in the gold plating bath may, for example, be an inorganic acid or an organic acid such as phosphoric acid, boric acid, citric acid, formic acid, phthalic acid or tartaric acid, or the like. The blending amount of the buffer in the gold plating bath can be appropriately set in a range in which the solute in the plating bath does not cause salt precipitation due to supersaturation. In the case where, for example, phosphate, boric acid, citric acid, tartaric acid, and the like are blended as a buffer, the blending amount is preferably 1 to 300 g/L. If the amount of the buffer is less than 1 g/L', the buffering effect is weak, and the bath stability is likely to deteriorate as the pH is lowered. As a result, there is a case where the components constituting the plating bath are decomposed. When the amount of the buffer to be added exceeds 30,000 g/L, there is a case where salt precipitation occurs at room temperature -11 - 201211323, and the limit current density decreases. Sometimes there are cases where the conductive salt and the buffer are the same compound. In this case, either one will play the role of the other. In the present gold plating bath, it is necessary to blend a sulfite-containing alkali metal salt or an ammonium sulfite salt to form a precipitation promoter as long as it is blended with at least one of an alkali metal sulfite salt and an ammonium sulfite salt. The amount of the precipitation promoter to be added in the gold plating bath is preferably from 1 mg/L to 18 g/L, more preferably from 10 mg/L to 10 g/L, and particularly preferably from 0.1 to 5 g/L, based on the sulfite ion. When the amount of the precipitation promoter is more than 10 μg/L in terms of sulfite ions, particularly when the cathode current density is 〇.2 A/dm 2 or more, the cathode current efficiency is lowered and electroplating is generated. The situation of coke. When the amount of the precipitation promoter blended exceeds 18 g/L by the sulfite ion, the above abnormality may occur under a wide range of the cathode current density. In the present gold plating bath, in addition to the above-mentioned precipitation promoter, it is preferable to further incorporate ethylenediaminetetraacetate. The use of the above-mentioned precipitation promoter and ethylenediaminetetraacetate, particularly at a cathode current density of 0.1 to 0.5 A/dm2, can improve the cathode current efficiency, and is therefore very suitable. The blending amount of ethylenediamine tetraacetate in the gold plating bath is preferably 0.1 to 20 g/L, preferably 0.5 to 5 g/L. In the case where the blending amount of ethylenediaminetetraacetate exceeds 2 〇g/L, the synergistic effect of the above-mentioned precipitation promoter and ethylenediaminetetraacetate is limited, and thus it does not meet economic benefits. When the blending amount of ethylenediaminetetraacetate exceeds 30 g/L, there is a case where the limit current density is lowered and electroplating is burnt. The pH of the gold plating bath is usually 3.0 to 10.0 and 3.5 to 8.5. In the case where the pH is less than 3.0, the plating bath is significantly unstable. As a result, there is a case where the components constituting the plating bath are decomposed and the gold compound is precipitated in 8 -12 to 201211323. When the pH exceeds 1 0.0, there is a case where the limit current density is lowered and the plating is burnt. In addition, as a result of the dissolution of the shielding material used to form the wiring pattern on the printed circuit board, the target wiring pattern may not be formed. The pH adjusting agent may, for example, be a mineral acid such as sulfuric acid or phosphoric acid or citric acid or An organic acid such as a carboxylic acid or a hydroxycarboxylic acid, or a base such as sodium hydroxide, potassium hydroxide or ammonia. The liquid temperature at the time of using the gold plating bath for the shovel is preferably 40 to 80 ° C, and preferably 5 5 to 70 ° C. The current density at the time of electroplating using this gold plating bath was 0.01 to 1.5 A/dm2. In particular, in the case where the gold concentration of the gold plating bath is 2 to 4 g/L, the current density is preferably 〜. 5 to 0.5 A/dm 2 . By using the plating bath for electroplating, the gold source or other components constituting the plating bath are consumed. This gold plating bath can be used for three rounds (all rounds of the gold source in the plating bath is set to one round) by supplementing the gold source or other components constituting the plating bath. The base material of the gold plating bath is metallized by gold plating or metallized by gold sputtering, and is not selected as an electroplated object if it is an electrically conductive object. The gold plating bath can be used to form a gold plating film on, for example, a printed wiring substrate or an electronic industrial component such as a 1C package, a germanium wafer, or a compound wafer. In particular, it is suitably used in the case where a gold plating film is formed on a printed wiring board. -13-201211323 [Examples] Hereinafter, the present invention will be specifically described by way of examples and comparative examples. The invention is not limited by the following examples. [Production of test piece] A 0.1 dm2 brass plate having a 5 μm gloss nickel coating film was formed, followed by alkali degreasing and electrolytic degreasing, followed by washing with pure water. The brass plate was immersed in 1% sulfuric acid and washed with pure water. Next, a gold plating film was formed on the copper plate using a cyanide electrolytic gold primer bath of the following formulation. The plating conditions were pH 5.5, plating temperature 50 ° C, current density 2 A/dm 2 , plating time 30 seconds. The brass plate on which the gold-plated film was formed was washed with pure water and then dried to prepare a test piece. This test piece was used for evaluation other than gold film thickness measurement, wire tensile test, and solder ball shear test. [Cyanide Electrolytic Gold Priming Bath]

Second gold (I) potassium (in terms of gold concentration) lg / L potassium second potassium 80g / L

Citric acid 20g/L

Potassium citrate 40g/L

[Step of Cyanide Electroless Gold Plating] Using the plating solution shown in each of the examples, a gold plating film was formed on the B G A panel and the test piece (hereinafter also referred to as "electrodeposited material"). 8 -14- 201211323 The plating procedure is as follows. First, the mass of the object to be plated is measured, and alkali degreasing and electrolytic degreasing are sequentially performed, and washed with pure water. It was then immersed in 10% sulfuric acid and washed with pure water. Next, using each of the cyanide electrolytic gold plating solutions shown in the respective Examples and Comparative Examples, a gold alloy film was formed on the object to be plated by the plating conditions shown in the respective Examples and Comparative Examples. Then, it was washed with pure water and dried, and the mass of the plated material was measured. The electric ore was carried out in a 10,000 mL beaker. Further, the cathode current density and the ore time of the 'cyanide electrolytic gold plating bath are as shown in Table 1. [Table 1] Cathodic current density (A/d nf) 0.0 5 0. 1 0 . 2 0 . 3 0. 4 Plating time (minutes) 18 9 4. 5 3 2 . 2 5 [Cathode current efficiency (CE)] The mass of gold deposited to the test piece was determined by measuring the quality of the test piece before and after electroplating. The mass of the precipitated gold is divided by the theoretical precipitation mass and expressed as a percentage. The theoretical precipitation quality of gold is calculated from the amount of electricity. [Evaluation by Wire Tensile Test] The wire tensile test was carried out using each of the BGA panels formed with the gold plating film obtained by the above plating step. A plurality of patterns have been formed on the BGA panel, and two adjacent patterns are used as test patterns. Among the two test patterns, the wire tensile test was performed at any 18 manner as described below. First, apply a load of 50gf at point 1 (one end) of a gold wire with a diameter of 1 mil (〇·00 1 inch) to 〇.〇5 watts of -15-201211323 at 15 (TC temperature retention) 0.05 seconds, and crimped to the first pattern of the BGA panel. On the other hand, a load of 100 gf is applied at the second point (the other end) of the gold wire, and the output of 0.1 watt is maintained at a temperature of 150 t for 1 second. The bell is crimped to the second pattern of the BGA panel (the pattern adjacent to the first pattern). Then the tensile strength of the wire after crimping is measured using K&S 1 48 8PLUS. The standard load is Serial NO. 926-L-LAB-102. [Evaluation by solder ball shear test] The ball ball shear test was performed using a BGA panel formed with a gold-plated film obtained by the above plating step. A plurality of BGA panels have been formed. For each pattern, use any two of the patterns as the test pattern. In this test pattern, the solder ball shear test is performed at any 1〇 by the method described below. First, the flux is coated. The cloth is formed on the gold-plated film formed on the BGA panel, and a solder ball with a diameter of 〇45 mm is attached thereto (solder ball alloy) Specification SAC305). Reflow the BGA panel in the atmosphere at 150 °C (60 seconds) ~ 180 °C (30 seconds) ~ 245 °C (63 seconds) ~ 100 °C (60 seconds) The solder ball is bonded to the BGA panel. The scratch test is performed at a position where the height of the solder ball and the BGA panel is 1/4 of the height of the solder ball apex (see Fig. 2). The scratch speed is set to lOOpm/sec. The measurement system was made by Technoalpha's XYZTEC series, model CONDOR70-3. The results were expressed in terms of strength (N) and fracture mode (good or bad). [Evaluation of plating thickness (CV)] -16- 201211323 The thickness of the gold film was measured using a BGA panel formed with the gold plating film obtained by the above plating step. A plurality of patterns were formed on the BGA panel, and any two of the patterns were used as the test pattern. In the pattern, gold is measured at each of the front side (wafer side) and the back side (tin ball side).

Film thickness (see Figure 1). CV 値 (%) ' was calculated by the following formula (1), and CV 値 was used as an index of plating uniformity. [Number 1] CV 値 (%) = 1 〇〇X α / Ε · · · Formula (1) f tr ...: Standard deviation (E. · · Thickness of film thickness of gold-plated film 値 [Determination of gold film thickness The measurement was carried out using a fluorescent X-ray film thickness meter SFT-9200 (Seik 〇 electron). [Example 1] The gold plating film was formed on the test piece by using the plating bath of the following composition in the plating conditions shown in Table 2; BGA panel.

Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L

Citric acid 15g/L

Potassium citrate 125g/L

Potassium formate 100g/L

Sodium sulfite 2 g/L barium sulfate (calculated as cerium concentration) 0.5 mg/L The obtained gold-plated film has a film thickness of 0.70 to 75.75 μm, and is semi-glossy of uniform -17-201211323. As shown in Table 2, the results of the cathode current efficiency, the film thickness variation coefficient, the wire tensile test, and the solder ball shear test were good in the range of the cathode current density of 〇.05 to 0.4 A/dm2. [Table 2] Cathodic current density (A/dm2) 0. 0 5 0 . 1 0 . 2 0. 3 0. 4 Plating conditions Plating bath pH 6. 3 Same as left and left left with left left plating bath Ugly 6 5 Same as left left and left left Stirring in the same left and left as the left and left (300 rpm) Cathodic current efficiency (CE) (%) 9 4 9 7 10 0 9 8 9 8 Film thickness coefficient of variation (CV値) 1 Surface 3. 8 3 . 7 3 . 9 3 . 9 4. 0 Evaluation (%)|Back 3 · 2 3 . 3 3 . 2 3 . 3 3. 4 Result Wire Tensile Strength (gf) 6·0 ～8·5 (Fracture Mode) (Good) Same as Left and Left Left Welding shear strength (N) (breaking mode) 8·0 to 10.0 (good) Same as left and left, same as left and left [Comparative Example 1] With the plating conditions shown in Table 3, the gold plating film was formed using the plating bath of the following composition. In test strips and BGA panels. Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L citric acid 15g/L potassium citrate 125g/L potassium formate 100g/L barium sulfate (calculated as cesium concentration) 0.5mg/L -18- The gold-plated film obtained in 201211323 has a film thickness of 0.40 to 7070 μm and has a uniform semi-gloss. The results of cathode current efficiency, film thickness variation coefficient, wire tensile test and solder ball shear test are shown in Table 3. In particular, the cathode current efficiency is low under the condition that the cathode current density is 〇 1 A/dm 2 or less. Under the condition that the cathode current density is 〇.〇5A/dm2 and 〇.lA/dm2, the cathode current efficiency is low, so the wire tensile test and the solder ball shear test are not performed. [Table 3] Electroplating conditions Cathodic current density (A/dm 〇 0.0 5 0. 1 0· 2 0. 3 0. 4 Plating bath pH 6. 3 Same as left and left with left and left left plating bath temperature (°C) 6 5 Same as left and left Same as left stirring (300 rpm) Same as left and left as the same as left and left. Results of cathode current efficiency (CE) (%) 6 7 8 4 9 0 9 3 9 7 Film thickness coefficient of variation (CV値)|Surface 4. 6 4. 0 4. 2 4. 1 6, 1 (%) 丨 back 4. 3 4. 3 4. 3 4. 6 4. 7 Tensile strength (gf) (fracture mode) Not implemented with the left 6.0~ 8.0 (good) Same left and left welding shears Shear strength (N) (breaking mode) is not performed with the left side 7.0 to 10.5 (good) Same as left and left [Example 2] The plating conditions shown in Table 4 'the plating bath using the following composition' were used to form the gold plating film on the test piece, respectively. And BGA panel ° -19 - 201211323

Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L

Citric acid 15g/L

Potassium citrate 125g/L

Potassium formate 100g/L

Potassium sulfite 2.4g/L

The formic acid bismuth (calculated as the cerium concentration) has a film thickness of 0.70 to 0.75 μm, and a uniform semi-gloss. As shown in Table 4, the results of the cathode current efficiency, the film thickness variation coefficient, the wire tensile test, and the solder ball shear test were good in the range of the cathode current density of 〇.05 to 0.4 A/dm2. [Table 4] Electroplating conditions Cathodic current density (A/dm 〇 0.0 5 0. 1 0 . 2 0. 3 0· 4 Plating bath pH 6. 3 Same as left and left with left and left left bathing beach (1C) 6 5 Same as left and left with left and left Stirring (300 rpm) Same as left and left as the left and left. Evaluation of cathode current efficiency (CE) (%) 9 6 9 9 10 0 10 0 9 8 Na coefficient of variation (CV値) 丨 Surface 3. 7 2. 7 3. 0 4. 2 4. 0 (%) 丨 back 3. 6 2. 4 3. 4 3. 4 4. 2 wire tensile strength (gf) split mode) 6.0 ~ 8.5 (good) with left left left with left and left welding shear strength (N) (Fracture mode) 8.0 to 10.0 (good) Same as left and left with the same left and left -20 - 201211323 [Example 3] Using the ammonium bath of the following composition, the gold plating film was formed in the test under the plating conditions shown in Table 5 Film and BGA panels.

Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L

Citric acid 15g/L

Potassium citrate 225 g/L

Sodium sulfite 2g/L

Sodium ethylenediaminetetraacetate 4.4g/L

Cerium nitrate (calcium concentration) 5 mg/L The thickness of the gold-plated film obtained is 0.70 to 75.75 μm, and is uniform and semi-glossy. As shown in Table 5, the cathode current density is 〇.05~ The results of 'cathode current efficiency, film thickness variation coefficient, wire tensile test and solder ball shear test in the range of 0_4A/dm2 were good. 201211323 [Table 5] Cathodic current density (A / dmO 0.0 5 0. 1 0 · 2 0. 3 〇 · 4 plating bath pH 6. 3 with left and left with the same left and left plating conditions plating bath (t) 6 5 with the same left and left with the left Stirring in the same left and left with the same left and left (300rpm) Cathode efficiency (CE) (%) 9 4 9 9 10 0 10 0 9 9 Drive coefficient of variation (CV値) i surface 3. 9 3. 8 4. 0 4. 0 4 1 (%)丨Back 3. 4 3. 6 3. 4 3. 7 3. 8 Result Wire Tensile Strength (gf) 6.0 〜8·5 (Fracture Mode) (Good) Same as Left Left Same Left Left Same Left Welding Strength (N) 8.0~ (Fracture mode) 10.0 (Good) Same as left and left, same as left and left [Example 4] With the plating conditions shown in Table 6, the gold plating film was formed on the test piece and the BGA panel, respectively, using the plating bath of the following composition. .

Potassium dicyanate (I) potassium (in terms of gold concentration) 2g/L

Citric acid 15g/L

Potassium citrate 275 g/L

Sodium sulfite 1 g / L

Sodium ethylenediaminetetraacetate 4,4g/L

Barium sulfate (calculated as cerium concentration) The film thickness of the gold-plated film obtained by lmg/L is 〇6〇~〇.7〇lJm, and is uniform and semi-glossy. As shown in Table 6, the results of cathode current efficiency, film thickness variation coefficient, wire tensile test and solder ball shear test are good in the range of cathode current density 〇〇5~ 8 -22- 201211323 0.2 A/dm2. . [Table 6] Cathodic current density (A/dm2) 0. 05 0. 1 0.2 Plating conditions Plating bath pH 6. 3 Same left left plating bath temperature (t) 6 5 Same as left and left stirring in the same left and left (300 rpm) Cathodic current efficiency ( CE) (%) 9 5 9 8 9 2 Film thickness coefficient of variation (cv値) i Surface 3. 8 3 . 9 4, 2 Evaluation result (%) 丨 Back 3. 2 3 . 5 4. 5 Wire tensile strength (gf) 6.0 to 8.5 (fracture mode) (good) Same as left and left welding shear strength (N) 7.0~ (fracture mode) 10.0 (good) Same as left and left [Comparative Example 2] Under the plating conditions shown in Table 7, use The plating bath of the composition was formed into a gold-plated film on the test piece and the BGA panel, respectively. Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L citric acid 15g/L potassium citrate 225g/L sodium sulfite 20g/L -23- 201211323

The formic acid bismuth (calculated as cerium concentration) 1 mg/L The thickness of the gold-plated film obtained is 0.30 to 0.65 μm. It has a uniform semi-gloss in the range of a cathode current density of 〇.〇5 to 0.3 A/dm2. Electroplating scorching occurred under the condition that the cathode current density was 〇.4 A/dm2. As shown in Table 7, the cathode current efficiency and the film thickness variation coefficient were observed to be deteriorated under the condition that the cathode current density was 0.2 A/dm 2 or more. Further, in Comparative Example 2, the wire tensile test and the solder ball shear test were not performed. [Table 7] Cathodic current density (A/dm,) 0.0 5 0 . 1 0. 2 0. 3 0, 4 Electroplating bath pH 6. 3 left and left left and left with left condition plating bath temperature oc) 6 5 Same as left and left Same as left stirring in the same left and left as the same as left and left (300 rpm) Cathodic current efficiency (CE) (%) 9 2 9 0 8 2 7 2 6 2 Result Membrane coefficient of variation (CV値) 1 Surface 4. 2 3 . 4 5 . 2 6 5 5 . 8 (%)|Back side 4. 4 2. 8 5. 3 8 . 7 9 . 6 [Comparative Example 3] Using the plating conditions shown in Table 8, using the plating bath of the following composition, respectively, in the test The sheet and the BGA panel form a gold-plated film.

Diterpenoid gold (1) potassium (in terms of gold concentration) 3g / L citric acid 1 5g / L

Potassium citrate 22 5 g/L 8 -24- 201211323

Sodium sulfate 2.1 g/L

Barium sulfate (calculated as cerium concentration) 5 mg/L The obtained gold-plated film has a film thickness of 0.45 to 0.70 μm and a uniform semi-gloss. The cathode current efficiency and film thickness variation coefficient are shown in Table 8. Especially at a cathode current density of 0.1 A/dm2, the cathode current efficiency is low. In Comparative Example 3, the wire tensile test and the solder ball shear test were not performed. [Table 8] Cathodic current density (A/dm 〇 0.0 5 0 . 1 0. 2 0 . 3 0. 4 Electroplating bath pH 6.3 3 with the same left and left with the same condition left-handed mineral bath 0C) 6 5 with left and left with the same left and left stirring The same as the left and the same left and the same left (300rpm) Cathodic current efficiency (CE) (%) 7 0 8 5 9 1 9 5 9 2 Result film thickness coefficient of variation (cv値) 丨 surface 6. 6 3 . 5 3 . 5 3. 8 5 . 0 (%) j back 4. 9 4. 6 4. 5 3 . 5 3 . 8 [Comparative Example 4] Using the plating conditions shown in Table 9 'using the plating bath of the following composition, respectively, in the test piece and The BGA panel forms a gold-plated film. Reveal the various evaluation results in Table 9 °

Potassium dicyanate (I) potassium (in terms of gold concentration) 3g / L citric acid 1 5g / L

Potassium citrate 22 5g/L -25- 201211323

Potassium second potassium phosphate 35g/L

Cerium nitrate (based on cerium concentration) 10 mg/L The cathode current efficiency is low particularly under the condition that the cathode current density is 0.2 A/dm 2 or less. In Comparative Example 4, the wire tensile test and the ball shear test were not performed. [Table 9] Cathodic current density (A/dm2) 0. 0 5 0. 1 0. 2 0. 3 0. 4 Electroplating bath pH 6. 3 Same as left and left with left and left conditional bath temperature α) 6 5 Same as left and left Same as left stirring, left and right, left and right, left and right DOOrpm) Cathodic efficiency (CE) (%) 6 4.8 7 9.9 8 5.2 9 0.5 9 3. 1 Evaluation result Film thickness variation coefficient (CV値)|Surface 4. 4 4. 6 3 . 9 4. 0 4. 8 (%)|Back side 4. 6 4. 2 4. 0 4. 3 5 . 5 [Comparative Example 5] Using the plating conditions shown in Table 10, 'using the plating bath of the following composition, The gold plating film was formed on the test piece and the BGA panel, respectively. The various evaluation results are disclosed in Table 1.

Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L

Citric acid 15g/L

Potassium citrate 22 5 g/L

Potassium second potassium phosphate 17g/L

Barium sulphate (based on cerium concentration) 1 mg/L Especially at conditions where the cathode current density is 0.1 A/dm2 or less. 8 8-26- 201211323 The cathode current efficiency is low. The wire tensile test and the ball shear test were not carried out in Comparative Example 5. [Table 10] Cathodic current density (A/dm») 0.05 〇. 1 0. 2 0. 3 0. 4 Electroplating conditions Age Η 6. 3 Same as left and left with the same left and left as though (t:) 6 5 Same as left and left with left and left stirring The same as the left and the same left and the same left (300rpm) Cathodic current efficiency (CE) (%) 6 6. 2 8 1.1 9 0. 0 9 3. 2 9 5. 7 Evaluation results 变异 coefficient of variation (CV 値) 丨 surface 4. 1 3 9 4. 0 4. 6 5 . 8 4. 4 4. 3 4. 4 4. 0 5 . 0 [Example 5] Using the plating conditions shown in Table 11, a plating bath having the following composition was used. Sheet metal films are formed on the test piece and the BGA panel, respectively. Reveal the various evaluation results in Table 11 »

Potassium dicyanate (I) in terms of gold concentration 3g/L Citric acid 15g/L Potassium citrate 225g/L Potassium diphosphate 35g/L Sodium sulfite 2g/L Sodium citrate (based on cesium concentration) 1 Omg/L -27- 201211323 [Table 11] Electroplating conditions Cathodic current density (A/dm2) 0 . 1 0. 2 0 . 3 0. 4 Beach pH Same as left and left left with left left plating bath surface t) Same as left and left with left and left with left stirring The same as the left and the same left, the results of the cathode current efficiency. (CE) (%) 9 0. 9 9 7. 1 9 8.8 9 6. 6 film thickness coefficient of variation (cv値) i surface 2. 9 3 . 1 4. 2 4. 3 (%) i back 3.0 3. 6 4. 4 4. 6 Comparison of Comparative Example 4 and Comparative Example 5, in which a part of the organic acid salt was replaced with potassium second potassium phosphate as a conductive salt, compared with the organic acid salt only In comparison with Example 1, the cathode current efficiency was reduced as a whole. On the other hand, regarding the addition of sodium sulfite to Example 5 of Comparative Example 5, in particular, the cathode current efficiency in the low current density region can be improved, and the effect of adding sulfite ions can be confirmed. [Example 6] The gold plating film was formed on the test piece and the BGA panel, respectively, using the plating bath of the following composition using the electroplating conditions shown in Table 12. The results of various evaluations are not disclosed in Table 12. Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L citric acid 1 5g/L potassium citrate 125g/L potassium formate 100g/L -28- 201211323

The gold plating film obtained by dissolving 1 mg/L of sodium sulfite has a film thickness of 0.70 to 75.75 μm, and has a uniform semi-gloss. As shown in Table 12, the results of the cathode current efficiency, the film thickness variation coefficient, the wire tensile test, and the solder ball shear test were good in the range of the cathode current efficiency of 〇〇5 to 0.4 A/dm2. [Table 12] Cathodic current density (A/dm 〇 0.0 5 0 . 1 0. 2 0. 3 〇. 4 Electroplating. Conditional plating bath pH 6. 3 Same as left and left left with left left plating bath temperature (. 〇6 5 with left and left left Same as left stirring in the same left and left as the same as left and left (300 rpm) Cathodic current efficiency (CE) (%) 9 6 9 8 9 9 10 0 9 8 Film thickness coefficient of variation (CV値) 1 Surface 3. 7 3. 8 4. 0 4. 1 4. 0 “fruit (%) 丨 3 3. 4 3. 4 3. 3 3. 4 3 . 5 wire tensile strength (gf) (fracture mode) 6·0 8.5 (good) with left and left with the same left Welding shear strength (N) (fracture mode) 8.0 to 10.0 (good) Same as left and left, same as left and left [Example 7] With the plating conditions shown in Table 13, the gold plating film was formed by using a plating bath having the following composition. Test strips and BGA panels. The results of various evaluations are not disclosed in Table 13.

Potassium dicyanate (I) potassium (in terms of gold concentration) 3g/L citric acid 15g/L -29- 201211323

Potassium citrate 125 g/L

Potassium formate 100g/L

The gold plating film obtained by using potassium sulfite 1 5 g/L has a film thickness of 0.70 to 0.75 um and has a uniform semi-gloss. As shown in the table, the results of the cathode current efficiency, the film thickness variation coefficient, the wire tensile test, and the solder ball shear test were good in the range of the cathode current efficiency of 0.05 to 0.4 A/dm2. [Table 13] Cathode "flow density (A / dm») 0.05 0 . 1 0. 2 0. 3 0. 4 plating conditions money bath pH 6. 3 with left and left with the same left with the left plating bath temperature (t) 6 5 with the left with the left with the left Same as left, left, right, left, left, right (300ιριη) Cathodic current efficiency (CE) <%) 9 5 9 7 9 8 9 9 9 8 Film thickness coefficient of variation (CV値)|Surface 3. 9 4. 0 4. 1 3 . 9 3. 9 fpfe (%)丨3. 3 3. 6 3. 4 3 . 5 3. 5 Result Wire Tensile Strength (gf) (Fracture Mode) 6.0 ～8·5 (Good) Same as Left and Left Same as the left. Welding shear strength (N) (section type) 8.0~ 10.0 (good) Same as left and left with the same left and left [Simplified illustration] Figure 1 shows the evaluation of plating uniformity (CV) in the examples. An explanatory view of the measurement portion of the measured gold film thickness. Fig. 1(a) shows the wafer side, and Fig. 1(b) shows the measurement side of the solder ball side. -30- 8 201211323 Fig. 2 is an explanatory view showing the position of the scratch of the solder ball in the welding shear test in the embodiment. [Description of main component symbols] 1 1 : Solder ball 20 : Sample pattern 2 1 : Surface measurement position 23 Measurement at the back side

Claims (1)

201211323 VII. Patent application scope 1. A cyanide electrolytic gold plating bath characterized by: dicyandiamide (I) acid alkali metal salt or dicyanogold (I) acid ammonium salt, which is 1.0 to 5.0 in terms of gold concentration g/L; crystallization modifier; conductive salt; buffer: and a precipitation promoter composed of any one or more of an alkali metal sulfite and an ammonium sulfite, and a sulfite ion of 0.1 mg/L to 1 8 g/ L. 2. A cyanide-based electrolytic gold plating bath characterized by comprising: dicyandiamide (I) acid alkali metal salt or dicyanogold (I) acid ammonium salt, which is 1.0 to 5.0 g/L in terms of gold concentration; Adjusting agent; conducting salt; buffering agent; a precipitation accelerator composed of any one or more of an alkali metal sulfite and an ammonium sulfite salt, and a sulfite ion of 0.1 mg/L to 18 g/L; Diamine tetraacetic acid. 3. For example, in the cyanide electrolytic gold plating bath of the second paragraph of the patent application, the concentration of ethylenediaminetetraacetic acid is l.lmg/L~20g/L° 4. The cyanide electrolysis according to item 1 or 2 of the patent application scope In the gold plating bath, the conductive salt is composed of one or more selected from the group consisting of citrate and citrate, and the concentration of the conductive salt is from 1 to 250 g/L. 5 • Electrolytic gold plating bath as claimed in Section 1 or 2 of the patent application. Where the knot 8 -32 - 201211323 crystal modifier is composed of a bismuth compound or a lead compound. The concentration of the aforementioned crystal modifier is determined by sharp or giving. .1~20mg/L. 6. The electrolytic gold plating bath according to claim 1 or 2, wherein the buffering agent is composed of one or more selected from the group consisting of phosphoric acid, boric acid, citric acid and the salts, and the concentration of the buffering agent is It is 1~3 00g/L. 7. A method for electroplating a printed wiring board, characterized in that: using a cyanide electrolytic shovel gold bath as claimed in claim 1 or 2, the plating current density is 0.05 to 0.5 A/dm2, and the plating bath is pH 3.5~ 8.5. Electroplating is carried out at a plating bath temperature of 55 to 70 °C. -33-