JPH0222160B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for manufacturing electronic components bonded with necessary components, such as semiconductor ceramic packages, lead frames, capacitors, printed circuit boards (gold patterns), power transistors, etc. Conventional techniques and problems to be solved by the invention Conventionally, for example, semiconductor ceramic packages
An electrolytic nickel plating film is formed directly on the required surface of the package base, or on top of a base plating film if necessary, and then a gold plating film is further formed on top of this. A semiconductor element is attached to the attached film and wire bonded. In addition, the lead frame is made by forming an electric nickel plating film directly on the base material or on a necessary undercoat plating film, and if desired, gold, silver, etc.
It is practiced to form a plating film of solder, tin, etc., and these electrolytic nickel plating films or gold,
The plating film of silver, solder, tin, etc. is soldered or brazed to other necessary parts. Conventionally, an electrical nickel plating film is formed as a surface treatment for electronic parts to be bonded with other parts, and if necessary, a bonding film of gold, silver, solder, tin, etc. is formed on top of the electrical nickel plating film. Necessary parts have been bonded to a nickel plating film or a bonding film by wire bonding, soldering, brazing, or the like. However, in the past, bonding defects often occurred in this bonding process, and deterioration of the bonded area over time sometimes occurred, but the present inventors believe that this is due to the uniformity of the film thickness of the electrolytic nickel plating film. It was discovered that this is a big problem. That is, as shown in FIG. 1, when applying electric nickel plating to, for example, a flat workpiece 1, excessive electricity is concentrated on the peripheral edge 2 of the workpiece 1, causing damage to this area. While the thickness of the plating film 4 becomes excessive, the amount of electricity applied to the center portion 3 of the object 1 to be processed is much smaller than that to the peripheral portion 2, so the thickness of the plating film 4 becomes thin. In this way, high current density areas and low current density areas occur on the object to be processed, resulting in variations in the plating film thickness. This variation in the plating film thickness due to the difference in current density that occurs in the workpiece is inevitable in electroplating, but in particular, in conventional electric nickel plating, a Watt bath is usually used as the nickel plating bath. As is clear from the results of experiments described below, the Watt bath has poor uniform electrodeposition properties, so the difference in plating film thickness between the high current density area and the low current density area becomes more pronounced. Therefore, when using a plating bath with such poor uniformity of electrodeposition, even if the average film thickness is plated to a predetermined thickness, in reality, the plating in the low current density area is poor. The film thickness is quite thin,
For this reason, when bonding necessary parts to this nickel plating film or a bonding film formed on this nickel plating film, bonding performance may be poor in the low current density area where the nickel plating film is thin. In addition, deterioration occurs over time, causing problems such as the nickel plating film not functioning sufficiently as a barrier layer for the bonding film. In this case, the film thickness of the low current density part of the nickel plated film can be increased by extending the plating time, but this method not only causes a decrease in productivity due to the prolongation of the plating time, but also The plating film thickness in the dense areas becomes excessive, causing problems in dimensional accuracy. The present invention was made in view of the above circumstances, and it is an object of the present invention to provide a method for manufacturing electronic components that prevents as much as possible the above-mentioned bonding defects and deterioration of bonding points over time and has excellent dimensional accuracy. shall be. Means and Effects for Solving the Problems The present inventors believe that the cause of poor bonding and deterioration over time of the bonding location is the thin film thickness in the low current density area as described above, and that the low current density If you ensure that the film thickness of the part is greater than the required film thickness,
In view of the fact that the film thickness in the high current density area becomes excessive and causes problems in the dimensional accuracy of electronic components, we have conducted various studies and found that in order to achieve the above objective, electrolytic nickel plating should be applied. In order to minimize the difference in film thickness between the low current density area and the high current density area, it is necessary to use a plating bath with good uniformity of electrodeposition, specifically a Haring cell with good uniformity of electrodeposition. It has been found that it is effective to perform plating using a plating bath of 25% or more when the distance ratio between the cathode and anode of the sheet is set to 5.
In addition, it is effective to use a plating bath with a uniform electrodeposition of 25% or more when performing not only electric nickel plating but also electric nickel alloy plating, electric iron plating, and electric cobalt plating. The present inventors have discovered that such uniform electrodeposition can be achieved by using the following electroplating bath, and have thus completed the present invention. Therefore, in the present invention, an electric nickel plating film, an electric cobalt plating film, an electric iron plating film, or an electric alloy plating film thereof is formed on the required surface of an electronic component base directly or through a base film, In a method for manufacturing an electronic component in which necessary components are bonded to this electroplated film or a bonding film formed on this film, one or more water-soluble salts of metals selected from nickel, cobalt, and iron are used. 10
~100g/, 200~500g/of one or more of metal halides, sulfates, and sulfamates selected from alkali metals, alkaline earth metals, and aluminum, organic carboxylic acids and their salts as buffers, boric acid, ammonium hydroxide,
By using an electroplating bath containing one or more water-soluble compounds selected from ammonium salts and amines, the distance ratio between the two cathode plates and the anode plate can be adjusted using a Haring cell. According to the present invention, there is provided a method for manufacturing an electronic component, characterized in that the above-mentioned electroplated film is formed with a uniform electrodeposition of 25% or more when measured at a temperature of 5.
It is possible to obtain an electronic component in which defective bonding such as wire bonding, soldering, brazing, etc. is prevented, deterioration of the bonding area over time is suppressed, and the barrier effect of the electroplated film against the bonding film is effectively exhibited. The present invention will be explained in more detail below. The present invention is for manufacturing electronic components to be bonded with required parts, such as semiconductor ceramic packages, lead frames, capacitors, printed circuit boards (gold patterns, etc.), power transistors, etc. First, the required surface of these electronic component bases is Electric nickel plating film directly or through a base film,
An electric cobalt plating film, an electric iron plating film, or an electric alloy plating film thereof is formed. In this case, the base film may be the material of the electronic component,
It is selected as appropriate depending on the type, purpose, etc. In addition, in the present invention, an electrolytic nickel plating film, an electrolytic cobalt plating film, an electrolytic iron plating film, or an electrolytic alloy plating film thereof is used in the present invention. It is formed using a plating bath having a uniform electrodeposition property of 25% or more, more preferably 35% or more when the distance ratio between the electrode plate and the anode plate is set to 5. Note that the uniform electrodeposition property is a value measured by the method described below. Here, such a plating bath having a uniform electrodeposition of 25% or more is one containing one or more water-soluble salts of metals selected from nickel, cobalt, and iron.
~100g/, 200~500g/of one or more of metal halides, sulfates, and sulfamates selected from alkali metals, alkaline earth metals, and aluminum, organic carboxylic acids and their salts as buffers, boric acid, ammonium hydroxide,
An electroplating bath containing one or more water-soluble compounds selected from ammonium salts and amines is used. More specifically, nickel, cobalt, iron sulfates, sulfamates, halides, etc., specifically nickel sulfate, ferrous sulfate, cobalt sulfate,
Examples include nickel chloride, ferrous chloride, cobalt chloride, nickel sulfamate, ferrous sulfamate, and cobalt sulfamate, and these metal salts are used at a concentration of 10 to 100 g/g. When obtaining an alloy plating film, two or more of the above water-soluble metal salts or the above water-soluble metal salts are used as the main component, and tungstic acid and its salts, molybdic acid and its salts, zinc sulfate, zinc chloride, etc. Water-soluble salts of the desired metals to be alloyed with nickel, iron, and cobalt can be selected and used, such as zinc salts, copper salts such as copper sulfate, copper chloride, tin salts such as tin sulfate, tin chloride, etc. can. In addition, the concentration of these metal salts to be alloyed is selected depending on the alloy composition, but
Use so that the total metal salt concentration is within the range of 100g/or less. The conductive salt is one or two of metal halides, sulfates, and sulfamates selected from alkali metals, alkaline earth metals, and aluminum.
It is preferable to use more than one species. Specifically, lithium chloride, sodium chloride, potassium chloride, aluminum chloride, ammonium chloride, magnesium chloride, sodium bromide, potassium bromide, lithium sulfate, sodium sulfate, potassium sulfate, aluminum sulfate, sodium sulfamate, potassium sulfamate, etc. is exemplified. The amount of these conductive salts used is 200 to 500 g/, and by using these conductive salts at a high concentration of 200 g/or more, high uniformity of electrodeposition can be achieved reliably. In addition to the above components, the plating bath used in the present invention further contains organic carboxylic acids and their salts as buffering agents.
One or more water-soluble compounds selected from boric acid, ammonium hydroxide, ammonium salts, and amines are added, and by using these buffers in combination with the conductive salt, uniform electrodeposition can be achieved. It can be further improved. More specifically, examples of the buffer include malic acid, ammonium malate, succinic acid, ammonium succinate,
Potassium acetate, sodium acetate, ammonium tartrate, ascorbic acid, citric acid, ammonium citrate, lactic acid, pyruvic acid, propionic acid, butyric acid, formic acid, acetic acid, glycolic acid, oxalacetic acid,
Examples include boric acid, aqueous ammonia, ethylenediamine, triethanolamine, ethanolamine, ammonium chloride, and ammonium bromide.
Among these, carboxylic acids and salts thereof, particularly citric acid and salts thereof are preferred, and ammonium salts are preferred as the salts. Triammonium citrate is particularly effective in terms of plating appearance and physical properties (low stress, flexibility). The amount of the above buffer used is not necessarily limited, but when using organic carboxylic acids and their salts,
It is preferable to set the amount to 300 g/, particularly 10 to 200 g/. In addition, when using boric acid, 20 to 50g/
, especially 30 to 45 g/, when using ammonium salts other than ammonium hydroxide and ammonium carboxylate, and amines, 10 to 100 g/, especially 10 to
It is preferable to set it as 50g/. In this case, it is preferable that the ratio of the metal ions of the water-soluble metal salt to these buffering agents be 1:1 to 1:5 in terms of weight ratio from the viewpoint of further improving uniform electrodeposition. In addition, when ammonium carboxylate is used, good plating without scorching can be achieved even when the metal ion concentration of the water-soluble metal salt is as low as 5 to 30 g/m, and uniform electrodeposition is further improved. Therefore, the metal ion concentration of the water-soluble metal salt can be set to the above-mentioned low concentration. Furthermore, hydrochloric acid or sulfuric acid can be added to the plating bath used in the present invention, thereby further improving uniform electrodeposition. Its usage is
The amount is preferably 0.1 to 30 g/, particularly 1 to 3 g/. In this case, the concentration of water-soluble metal salt should be adjusted to 30~
It is preferable to use a low concentration of 100 g/l because a plated film with high uniformity of electrodeposition can be obtained. In addition, if necessary, hypophosphorous acid,
Approximately 1 to 100 g of phosphorous acid, salts thereof, amine borane compounds, and hydrazine compounds can be added, thereby making it possible to obtain a phosphorus-containing or boron-containing plating film. Such a phosphorus- or boron-containing plating film becomes a hard film with a micro-Vickers hardness of Hv500 to 800, and a film with even higher hardness can be obtained by heat treatment in the same way as a chemical nickel plating film. In addition, the boron-containing alloy plating film exhibits excellent solderability, bonding properties, heat resistance, and wear resistance. Additionally, the electroplating bath may contain additives commonly used as brighteners, leveling agents, etc., such as saccharin, sodium naphthalene disulfonate, sodium naphthalene trisulfonate, sodium allylsulfonate, and propagyl sulfonate. Appropriate amounts of sodium, butynediol, propargyl alcohol, coumarin, formalin, etc. can be added. In addition, the pH of the plating bath is preferably 1 to 12, particularly 1 to 10, and may be any of acidic, neutral, and alkaline baths, but its effects are particularly effective in acidic plating. do. The plating conditions when plating using the above-mentioned plating bath are not particularly limited, but the plating temperature is 10 to 70°C, and the cathode current density is 0.01 to 50 A/ ^dm2.
The following conditions may be suitably employed. Further, if necessary, stirring can be performed by methods such as air stirring, cathode locking, liquid circulation using a pump, etc., and propeller stirring. The anode is selected according to the type of plating solution, and soluble anodes such as electric nickel, sulfur-containing nickel, carbonized nickel, iron, cobalt, and alloy anodes are used.
In some cases, an insoluble anode such as platinum or carbon may also be used. In addition, when plating using the above-mentioned plating bath, the current efficiency should be set to 60 to 100% to achieve high uniformity of electrodeposition and increase the thickness of the plating film in the low current density area. It is preferable from the viewpoint of obtaining. In the present invention, an electrolytic nickel plating film, an electrolytic cobalt plating film, an electrolytic iron plating film, or an electrolytic alloy plating film thereof is formed in this way, but in this case, the film thickness of these electroplating films is is selected depending on the type of electronic component, usage, etc., and is usually 1.
The thickness can be approximately 10 μm. In the present invention, a bonding film is formed on this electroplated film if necessary. As the bonding film, a suitable bonding film of gold, silver, solder, tin, etc. is formed depending on the type of electronic component, its use, etc. Note that a known electroplating method or the like may be employed as a method for forming these bonding films. In addition, when bonding the above-mentioned electroplated film or bonding film to the required parts, known bonding methods such as wire bonding, soldering, and brazing are used, and the bonding is performed according to each conventional method. can be done. Effects of the Invention According to the present invention, a plating bath having a uniform electrodeposition property of 25% or more, that is, 10 to 10% of one or more water-soluble salts of metals selected from nickel, cobalt, and iron, is used.
100 g/200 to 500 g/of one or more of metal halides, sulfates, and sulfamates selected from alkali metals, alkaline earth metals, and aluminum, organic carboxylic acids and their salts, and boron as buffering agents. acid, ammonium hydroxide,
An electroplating bath containing one or more water-soluble compounds selected from ammonium salts and amines is used to produce electroplated nickel, cobalt, iron, or alloys of these. By forming a plated film, it has excellent bonding properties and the stability of the bonding area over time.The plated film has a good barrier effect against the bonding film, and has excellent dimensional accuracy. Electronic components can be obtained. Hereinafter, the effects of the present invention will be specifically illustrated by experimental examples and examples. Experimental example 1 NiSO ₄・6H ₂ O 20g / NiCl ₂・6H ₂ O 20 〃 NaCl 300 〃 H ₃ BO ₃ 30 〃 Concentrated sulfuric acid 1.5ml / PH 1 Using the above electroplating solution, temperature 55℃, cathode When plating was carried out under air agitation at a current density of 2 A/dm ² , a nickel plating film was obtained which had an appearance very similar to the plating obtained from a Watt bath. Experimental example 2 NiSO ₄・6H ₂ O 20g/ NiCl ₂・6H ₂ O 20 〃 KCl 300 〃 Sodium citrate 40 〃 PH 3 Using the above electroplating solution, the temperature was 55℃ and the cathode current density was 2A/dm ² When plating was carried out under air agitation, a flexible nickel plating film with a silvery white luster was obtained. Experimental example 3 Nickel sulfamate 40g / Na ₂ SO ₄ 250 〃 NaCl 30 〃 Malic acid 40 〃 Ammonia water 60ml / PH 6 Using the above electroplating solution, air was applied at a temperature of 55℃ and a cathode current density of 2A/dm ² When plating was carried out under stirring, a dark, matte, low stress and flexible nickel plating film was obtained. Experimental example 4 NiCl ₂・6H ₂ O 40g/ KCl 300 〃 NH ₄ Cl 60 〃 H ₃ BO ₃ 10 〃 PH 3.5 Using the above electroplating solution, air was applied at a temperature of 55℃ and a cathode current density of 2A/dm ² When plating was carried out under stirring, a flexible nickel plating film with a matte black color was obtained. Experimental example 5 NiCl ₂ 6H ₂ O 100g / KCl 270 〃 H ₃ BO ₃ 30 〃 PH 4.2 〃 Using the above electroplating solution, plating was carried out under air agitation at a temperature of 55℃ and a cathode current density of 2A/dm ^2. As a result of polishing, a brownish-gray, matte nickel plating film was obtained. Experimental example 6 NiSO ₆・6H ₂ O 50g / LiCl 300 〃 Succinic acid 40 〃 Ammonia water 70ml / Diethylamine borane 1g / PH 6 Using the above electroplating solution, at a temperature of 55℃ and a cathode current density of 2A/dm ² When plating was carried out under air agitation, a completely glossy nickel-boron alloy plated film was obtained. Experimental example 7 NiSO ₄・6H ₂ O 60g / KCl 250 〃 Succinic acid 40 〃 Ammonia water 70ml / Phosphorous acid 50g / Concentrated sulfuric acid 1.5ml / PH 2 Using the above electroplating solution, temperature 55℃, cathode current When plating was carried out under air agitation at a density of 2 A/dm ² , a completely glossy nickel-phosphorus alloy plated film was obtained. Experimental example 8 NiSO ₄・6H ₂ O 20g/ NiCl ₂・6H ₂ O 30 〃 Na ₂ SO ₄ 300 〃 H ₃ BO ₃ 40 〃 Satucharin sodium 2 〃 2-Butyne-1,4-diol 0.2 〃 PH 4.2 Above When plating was carried out using an electroplating solution at a temperature of 55° C. and a cathode current density of 2 A/dm ² with air stirring, a completely glossy nickel plating film was obtained. Experimental example 9 NiCl ₂・6H ₂ O 40g / Sodium molybdate 10 〃 KCl 250 〃 Succinic acid 40 〃 Ammonia water 70ml / PH 10 Using the above electroplating solution, temperature 55℃, cathode current density 2A / dm ² When plating was carried out under air agitation, a semi-glossy nickel-molybdenum alloy plating film was obtained. Experimental example 10 CoSO ₄・7H ₂ O 50g/ KBr 300 〃 Triammonium citrate 10 〃 PH 4.8 Using the above electroplating solution, plating was carried out at a temperature of 55℃ and a cathode current density of 2A/dm ² under air stirring. As a result, a matte and flexible cobalt plating film was obtained. Experimental example 11 FeSO ₄・7H ₂ O 40g/ NaBr 250 〃 Ammonium acetate 20 〃 PH 3.5 Using the above electroplating solution, plating was performed at a temperature of 55℃ and a cathode current density of 2A/dm ² with air stirring. After aging, a matte and flexible iron-plated film was obtained. Comparative experiment example 1 NiSO ₄・6H ₂ O 280g / NiCl ₂・6H ₂ O 45 〃 H ₃ BO ₃ 40 〃 PH 4.4 Using the above electroplating solution (Watt bath), the temperature was 55°C and the cathode current density was 2A. Plating was carried out under air agitation at /dm ² to obtain a nickel plated film. Comparative experiment example 2 Nickel sulfamate 300g / NiCl _{2.6H 2} O 30 〃 H ₃ BO ₃ 40 〃 PH 4.4 Using the above electroplating solution, at a temperature of 55°C and a cathode current density of 2A/dm ² under air stirring A nickel plating film was obtained. Comparative experiment example 3 NiSO ₄・6H ₂ O 280g/ NiCl ₂・6H ₂ O 40 〃 CoSO ₄・7H ₂ O 35 〃 Sodium formate 25 〃 H ₃ BO ₃ 40 〃 PH 4.2 Using the above electroplating solution, Plating was carried out at a temperature of 55° C. and a cathode current density of 2 A/dm ² with air stirring to obtain a nickel-cobalt alloy plating film. Comparative Experiment Example 4 NiCl ₂・6H ₂ O 300g/H ₃ BO ₃ 35 〃 PH 4.2 Using the above electroplating solution, plating was performed at a temperature of 55°C and a cathode current density of 2A/dm ² under air agitation. , a nickel plating film was obtained. Next, the above Experimental Examples 1 to 11 and Comparative Experimental Examples 1 to 4
The uniform electrodeposition properties of the electroplating solution were examined using a Harling cell shown in FIG. Here, in Fig. 2, 5 is a Harling cell made of acrylic resin, and its internal dimensions are 240 mm in length,
It has a width of 63 mm and a depth of 100 mm, and 1500 ml of plating liquid 6 can be put inside it. Also, 7 is 61×100×1mm
The anode plate is attached to a support (not shown) and is adapted to be fixed in position within the Harling cell. 8,8 more
are cathode plates each having a size of 61 x 100 x 0.3 mm, which are disposed at both longitudinal ends of the Haring cell 5. When measuring uniform electrodeposition using this Harling cell, fix the anode plate at the required position in the Harling cell and measure the distance ratio (a/b) between the two cathode plates and the anode plate. (distance ratio 5 in the present invention). After plating for a predetermined period of time, the weight of the plating film deposited on the two cathode plates is measured, and uniform electrodeposition is calculated from the following formula. In this experiment, an electric nickel plate was used as the anode, and two copper plates with tape coating on the back were used as the cathode.The distance ratio was set to 5, the electroplating solution was kept at a temperature of 55°C, and gentle air agitation was used. While doing so, electricity was applied for 30 minutes at a total current of 2A. T (%) = P−M/P+M−2×100 However, T: Uniform electrodeposition P: Distance ratio a/b (5 in this experiment) M: Weight ratio of the film deposited on the cathode (M ₁ / _M2 : _M1 is the weight of the cathode closer to the anode, _M2
is the weight of the cathode farthest from the anode) As is clear from the above equation, uniform electrodeposition is 0.
% means that the weight ratio of the plating film deposited on the cathode is equal to the distance ratio between the anode and the cathode, and this means that the difference in plating film thickness occurs according to the difference in current distribution to the cathode. means. On the other hand, 100% uniform electrodeposition means that the weight of the deposited film deposited on the two cathodes is the same regardless of the distance ratio between the anode and cathode, and the current distribution with respect to the cathode is 100%. This means that even if this occurs, the plating film thickness is uniform.

【table】

[Table] Example After activating the metallization of a ceramic IC package, nickel plating was performed for 5 minutes using the plating solution of Experimental Example 2 under the same conditions as Experimental Example 2. Next, a gold plating film having an average thickness of 2 μm was formed on this nickel plating film according to a conventional method. A silicon chip was bonded to this gold-plated film by the gold-silicon eutectic method. its bonding properties and its changes over time.
When tested according to MIL standard 883C, it passed. For comparison, an experiment similar to the above was conducted using the plating solution of Comparative Experiment Example 1, and as a result, it failed to meet the above standards. Note that the average film thickness when plating was performed using the plating methods of Experimental Example 2 and Comparative Experimental Example 1 was 1.9 μm, which was the same.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the state of formation of a plating film on a conventional plated object when plated by the electric nickel plating method, and FIG. 2 is a schematic cross-sectional view of a Harling cell. 5...Harling cell, 6...Anode plate, 7...
Cathode plate.

Claims (1)

[Claims] 1. An electric nickel plating film, an electric cobalt plating film, an electric iron plating film, or an electric alloy plating film thereof is formed on the required surface of an electronic component substrate directly or through a base film, and this electroplating film or In a method for manufacturing an electronic component in which necessary components are bonded to a bonding film formed on this film,
10 to 100 g of one or more water-soluble salts of metals selected from nickel, cobalt, and iron; halides, sulfates, and sulfamates of metals selected from alkali metals, alkaline earth metals, and aluminum; 200-500 of one or more types
g/, 1 of a water-soluble compound selected from organic carboxylic acids and their salts, boric acid, ammonium hydroxide, ammonium salts, and amines as a buffer.
By using an electroplating bath containing the species or two or more species, the uniform electrodeposition property when measured using a Haring cell with the distance ratio between the two cathode plates and the anode plate set to 5 is 25. % or more of the electroplated film.