JP2013249514A - Electrolytic silver plating solution for optical semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silver plating solution capable of stabilizing mounting reliability, light reflection characteristics, and corrosion resistance (particularly resistance to sulfurization corrosion) to a lead frame or a substrate of an optical semiconductor device and capable of improving these characteristics; and a plating method using the silver plating solution.SOLUTION: An electrolytic silver plating solution for a lead frame or a substrate of an optical semiconductor device is prepared by adding a soluble compound including at least one selected from the group consisting of Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I in a concentration range of 5 mg/L to 10 g/L to a silver plating solution including 20-250 g/L of a cyanide silver complex, 50-200 g/L of a free cyanogen salt and at least either one of a selenium compound and a sulfur compound. The electrolytic silver plating solution has a pH of 10-14.

Description

  The present invention relates to an electrolytic silver plating solution for a lead frame or a substrate for an optical semiconductor device, and a plating method using the electrolytic silver plating solution.

  2. Description of the Related Art Optical semiconductor devices such as light emitting diodes (LEDs) are widely used as light sources for lighting, various displays, backlights for liquid crystal televisions and mobile phones. These optical semiconductor devices are configured by mounting an optical semiconductor element on various substrates such as a lead frame, a printed circuit board, a ceramic substrate, and a flexible substrate by die bonding or wire bonding. In order to improve the mounting reliability, it is common that the lead frame or the substrate is subjected to either gold plating or silver plating. Gold plating is hard to oxidize and has high bonding reliability. However, since it easily absorbs light in the visible region emitted from the optical semiconductor element, silver plating having excellent light reflectivity with respect to light in the visible region is widely used. .

  For example, Patent Documents 1 and 2 disclose a method for producing a brightener that brightens a silver plating film. Further, for example, Patent Documents 3 and 4 disclose silver plating solutions devised so that partial plating can be performed in order to improve the die bonding property and wire bonding property of the silver plating film or increase the productivity. However, no consideration has been given to the light reflection characteristics required of a lead frame or substrate for an optical semiconductor device.

  On the other hand, Patent Document 5 discloses an LED mounting substrate in which the crystal grain size of the outermost surface of the silver plating film is adjusted in order to improve the light reflectance. Patent Document 6 discloses a semiconductor light emitting device having a lead frame in which a rhodium plating layer is formed on a silver plating layer. Further, Patent Document 7 discloses a lead frame for an optical semiconductor device in which a film made of a metal material having excellent sulfidation corrosion resistance is formed on the surface of a pure silver layer. It is only a conventional silver plating solution.

  In the conventional silver plating solution, it is difficult to make the light reflection characteristics of the silver plating film highly reliable. Specifically, for example, in a conventional lead frame plated with a silver plating solution, a silver plating film is mechanically modified by a resin molding machine during mounting and assembling of an optical semiconductor device, and various types of assembling are being performed. The silver plating film may be agglomerated and transformed by an appropriate heat treatment.

U.S. Pat. No. 2,807,576 U.S. Pat. No. 3,580,821 U.S. Pat. No. 4,247,372 Japanese Patent Laid-Open No. 05-222569 Japanese Patent No. 4367457 JP 2011-204790 A Japanese Patent No. 4763094

  The present invention has been made in view of the above problems, and its object is to provide mounting reliability, light reflection characteristics and corrosion resistance (particularly corrosion resistance against sulfidation corrosion) for a lead frame or a substrate for an optical semiconductor device. It is to provide a silver plating solution and a plating method using the silver plating solution that can stabilize these properties and improve these characteristics.

  As a result of intensive studies to solve the above problems, a silver plating solution dedicated to optical semiconductor devices has been completed.

That is, the present invention provides a silver plating solution containing at least one of a silver cyanide complex 20 to 250 g / L, a free cyan salt 50 to 200 g / L, a selenium compound and a sulfur compound, Ti, Zr, V, Soluble containing at least one selected from the group consisting of Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, I An electrolytic silver plating solution for a lead frame or substrate for an optical semiconductor device, wherein the compound is added in a concentration range of 5 mg / L to 10 g / L, and the pH is 10 to 14,
In a silver plating solution containing at least one of silver cyanide complex 20 to 250 g / L, electric conduction salt 50 to 250 g / L, free cyanate 0.1 to 30 g / L, selenium compound and sulfur compound, Ti , Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, I An electrolytic silver plating solution for a lead frame or substrate for an optical semiconductor device, wherein a soluble compound containing one kind is added in a concentration range of 5 mg / L to 10 g / L, and the pH is 7.5 to 14,
An electrically conductive lead frame or substrate is used as an anode, metallic silver, stainless steel, platinum group metal or titanium coated with a platinum group metal as a cathode, and the anode and the cathode are connected to the optical semiconductor device lead frame and substrate. The present invention provides a plating method in which the lead frame or the substrate is electroplated by being immersed in an electrolytic silver plating solution.
According to the silver plating solution and the plating method of the present invention, the plating solution is Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi. , As, P, Te, Br, and a soluble compound containing at least one selected from the group consisting of I, a small amount of Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I are fitted, deformation due to mechanical pressure during the mounting process, and thermal Aggregation of particles due to a simple history is difficult to occur, and the function as a silver reflective film having a high light reflectance can be maintained. Therefore, the light reflectance is remarkably improved and a high light reflectance can be maintained over a long period of time. Therefore, according to the silver plating solution and the plating method, by applying to a lead frame or substrate for an optical semiconductor device, for example, improvement in light emission efficiency as an LED, improvement in corrosion resistance, and stabilization of the quality of light characteristics between products. Can be obtained. For this reason, since the luminous flux improvement of LED can be implement | achieved, the reduction in the number of mounting components in a LED bulb and the reduction in the number of mounting of backlight LEDs for liquid crystal televisions enable energy saving and a reduction in manufacturing cost. In addition, the improvement of the corrosion resistance can extend the life of the LED. Moreover, since the variation in the light emitting characteristics of the LED is improved, the work loss in the manufacturing process can be reduced, and the manufacturing cost can be reduced.

  According to the present invention, it is possible to stabilize mounting reliability, light reflection characteristics, and corrosion resistance (particularly corrosion resistance against sulfidation corrosion) with respect to a lead frame or substrate for an optical semiconductor device, and to improve these characteristics. A silver plating solution that can be produced and a plating method using the silver plating solution can be provided.

The present invention is described in detail below.
An optical semiconductor device forms an electrical circuit, and an optical semiconductor element such as gallium nitride that emits light when an appropriate voltage is applied to a lead frame or a substrate (printed substrate, ceramic substrate, flexible substrate, etc.) with an appropriate paste, etc. It is often manufactured by die bonding and fixing, wire bonding to p-type and n-type electrodes with a gold wire or the like, and sealing with resin. The optical semiconductor device is mounted by solder reflow or the like when mounted on an actual LED bulb or the like.

  In order to industrially perform such an assembly process and a mounting process with stable quality, it is common to perform gold plating or silver plating on a lead frame or a substrate for an optical semiconductor device. In particular, silver plating has been widely put into practical use because high reflectance can be obtained. In addition to highly reliable wire bonding, stable die bonding, stable solder wettability, sealing resin adhesion, etc., this silver plating film has a light reflection that maintains high reflectivity over a long period of time. Rate characteristics are required. However, the conventional silver plating solution is mainly developed as a silver plating solution for lead frames of electronic parts such as ICs. Regarding the requirement of light reflectance characteristics to maintain a high reflectance over a long period of time, Nothing was considered.

  Therefore, when intensive research was conducted on silver plating solutions for lead frames and substrates for optical semiconductor devices, Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl. , Sb, Bi, As, P, Te, Br, lead for optical semiconductor devices using a silver plating solution to which a soluble compound containing at least one of them is added in a concentration range of 5 mg / L to 10 g / L It has been found that an optical semiconductor device capable of significantly improving light reflectance and maintaining high light reflectance over a long period of time can be manufactured by silver plating on a frame or a substrate.

  The detailed mechanism for obtaining these effects is not clear at present, but when electroplating is performed using the silver plating solution having the component structure of the present invention, a small amount of Ti, Zr, Since V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I are fitted, mechanical during the mounting process It is presumed that deformation due to a large pressure and particle aggregation due to thermal history are less likely to occur, and the function as a highly reflective silver reflector can be maintained. In particular, unlike the method of forming a silver film by vapor deposition or sputtering, the electroplating method forms an electrodeposited particle boundary in which impurities such as trace amounts of carbon are relatively high. It is considered that these incorporated elemental particles segregate at the particle boundary, and a film having a high light reflectance can be obtained and maintained. On the other hand, in the vapor deposition method or the sputtering method, it is considered that the particle boundary is easy to move, irregular reflection occurs, and high light reflection cannot be obtained. Moreover, unlike the silver plating solution composition of the present invention, in various conventional silver alloy plating solutions, alloy components other than silver are merely precipitated and alloyed, and the light reflectance is reduced by alloying. In addition to its drawbacks, the reflectivity is reduced during the assembly process, which makes industrial practical use impossible.

  Of course, the silver plating film obtained from the silver plating solution of the present invention is also excellent in highly reliable wire bonding properties, stable die bonding properties, stable solder wettability, sealing resin adhesion, and the like.

  As a silver source of the silver plating solution of the present invention, a silver cyanide complex is preferably used. Since the silver cyanide complex is stable in an aqueous solution and has a noble deposition potential, a dense silver plating film having good wire bonding properties can be obtained. As the cyanide complex, silver cyanide and potassium potassium cyanide are industrially easily available.

  The concentration of the silver cyanide complex is preferably 20 to 250 g / L, more preferably 50 to 150 g / L. If the silver cyanide complex concentration is less than 20 g / L, electrolysis of water starts at the same time, the silver plating film becomes rough, and not only wire bonding becomes difficult, but also the light reflectance decreases, which is not preferable. On the other hand, if the concentration of the silver cyanide complex exceeds 250 g / L, the viscosity of the silver plating solution becomes too high, the silver plating film becomes rough, and the light reflectance is greatly reduced, which is not preferable.

  A silver plating solution containing 20 to 250 g / L of a silver cyanide complex, 50 to 200 g / L of a free cyanate salt, selenium compound and sulfur compound is added to Ti, Zr, V, Mo, W, Co, Pd. A soluble compound comprising at least one selected from the group consisting of Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I In an electrolytic silver plating solution for an optical semiconductor device lead frame or substrate added in a concentration range of 10 g / L and having a pH of 10 to 14, free cyanide salt is used for maintaining electrical conductivity as a plating solution. Is an essential ingredient. As chemicals, potassium cyanide and sodium cyanide are easily available, and these single compositions or mixed salts may be used. The free cyanate concentration is preferably 50 to 200 g / L, more preferably 80 to 150 g / L. If the concentration of the free cyanate salt is less than 50 g / L, the electric conductivity of the plating solution is lowered, so that the silver plating film becomes rough and the light reflectance is lowered. On the other hand, if the free cyanide concentration exceeds 200 g / L, the viscosity of the plating solution becomes too high, the silver plating film becomes rough, and the light reflectance is greatly reduced, which is not preferable.

  In addition, a silver plating solution containing at least one of silver cyanide complex 20 to 250 g / L, electrically conductive salt 50 to 250 g / L, free cyanate 0.1 to 30 g / L, selenium compound and sulfur compound, Selected from the group consisting of Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, I In an electrolytic silver plating solution for an optical semiconductor device lead frame or substrate, a soluble compound containing at least one kind is added in a concentration range of 5 mg / L to 10 g / L, and the pH is 7.5 to 14. The salt is an indispensable component for stabilizing the electrodeposition of the silver cyanide complex, but since the electrical conductivity contains another electrical conductive salt, a lower concentration than the silver plating solution is sufficient, and free cyanide is sufficient. salt The degrees, but 0.1 to 30 g / L is preferred, more preferably from 1 to 15 g / L. If the free cyanide concentration is less than 0.1 g / L, abnormal precipitation occurs when the silver cyanide complex is electrodeposited, resulting in a rough silver plating film, and the light reflectance is lowered, which is not preferable. On the other hand, when the concentration of the free cyanide salt is 30 g / L or more, the electrical conductivity of the electrical conduction salt used together with the free cyanate salt is hindered, and cyan decomposition products are mixed in the silver plating film, so that the silver plating film becomes This is not preferable because the color changes and the light reflectance is lowered.

  To a silver plating solution containing at least one of silver cyanide complex 20 to 250 g / L, electric conduction salt 50 to 250 g / L, free cyanate 0.1 to 30 g / L, selenium compound and sulfur compound, Ti, Zr, At least one selected from the group consisting of V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I In an electrolytic silver plating solution for a lead frame or a substrate for an optical semiconductor device, wherein a soluble compound is added in a concentration range of 5 mg / L to 10 g / L and the pH is 7.5 to 14, the conductive salt is phosphorus The acid salt, nitrate salt, citrate salt, tartrate salt and the like are used alone or as a mixture thereof, but are not particularly limited as long as they are electrically conductive and water-soluble. More specifically, examples of the phosphate include dipotassium phosphate, disodium phosphate, monopotassium phosphate, monosodium phosphate, potassium pyrophosphate, ammonium phosphate, and the like. Examples of the nitrate include potassium nitrate, sodium nitrate, and ammonium nitrate. Examples of the citrate include potassium citrate and sodium citrate. Examples of tartrate salts include potassium tartrate and sodium tartrate.

  The concentration of the electrically conductive salt is preferably 50 to 250 g / L, and more preferably 80 to 150 g / L. If the concentration of the electroconductive salt is less than 50 g / L, the deposited silver film becomes coarse and the light reflectance decreases, which is not preferable. On the other hand, if the concentration of the electrically conductive salt exceeds 250 g / L, the viscosity of the plating solution is too high, so that the silver plating film becomes rough and the light reflectance decreases, which is not preferable.

  The brightener preferably contains a selenium compound, a sulfur compound, or both. These brighteners are components for making the silver plating film glossy by being contained in a small amount in the silver plating film and maintaining high light reflectance. Examples of the selenium compound of the brightener include potassium selenium cyanide, selenium cyanide, selenious acid, selenium oxide, and selenium oxide, but are not limited thereto as long as they exhibit gloss. The concentration of the selenium compound in the brightener is preferably 0.01 mg / L to 100 mg / L. Examples of the brightening agent sulfur compound include carbon disulfide, thiourea, thiolactic acid, thiouracil, thiobarbituric acid, cysteine, cystine, thioacetic acid, and mercaptobenzothiazole. It is not limited.

  Moreover, as a brightener, it is also possible to contain both a selenium compound and a sulfur compound. Further, the brightening agent sulfur compound may be a reaction product of one or more sulfur compounds such as carbon disulfide, thiourea, thiolactic acid, thiouracil, thiobarbituric acid, cysteine, cystine, thioacetic acid, mercaptobenzothiazole and the like. . The concentration of the sulfur compound as the brightener is preferably 0.05 g / L to 10 g / L.

  A silver plating solution containing 20 to 250 g / L of a silver cyanide complex, 50 to 200 g / L of a free cyanate salt, selenium compound and sulfur compound is added to Ti, Zr, V, Mo, W, Co, Pd. A soluble compound comprising at least one selected from the group consisting of Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I In an electrolytic silver plating solution for an optical semiconductor device lead frame or substrate added in a concentration range of 10 g / L and having a pH of 10 to 14, the pH is preferably 10 to 14. If the pH is less than 10, the silver cyanide complex becomes unstable, the plating solution tends to become cloudy, and the free cyanide salt tends to vaporize, which is not economical, which is not preferable.

  In addition, a silver plating solution containing at least one of silver cyanide complex 20 to 250 g / L, electrically conductive salt 50 to 250 g / L, free cyanate 0.1 to 30 g / L, selenium compound and sulfur compound, Selected from the group consisting of Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, I In an electrolytic silver plating solution for a lead frame or substrate for an optical semiconductor device, wherein a soluble compound containing at least one kind is added in a concentration range of 5 mg / L to 10 g / L, and the pH is 7.5 to 14, the pH is Preferably, it is 7.5-14. If the pH is less than 7.5, the silver cyanide complex becomes unstable, the plating solution tends to become cloudy, and the free cyanide salt tends to vaporize, which is not economical, which is not preferable.

  Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, added as additives to the silver plating solution of the present invention Soluble compounds including at least one selected from the group consisting of P, Te, Br, and I include titanium oxide, titanium hydroxide, titanium chloride, zirconium oxide, zirconium chloride, vanadium oxide, sodium molybdate, and tungsten oxide. Sodium, cobalt sulfate, palladium nitrate, palladium chloride, gold cyanide, potassium cyanide cyanide, sodium gold cyanide, ammonium gold cyanide, sodium gold sulfite, potassium sulfite, chloroauric acid, copper cyanide, copper sulfate, copper chloride , Zinc chloride, zinc sulfate, zinc oxide, gallium chloride, gallium oxide, germanium oxide, germanium chloride , Indium sulfate, indium chloride, tin chloride, tin oxide, tin sulfate, sodium stannate, thallium sulfate, thallium nitrate, thallium oxalate, antimony oxide, antimony potassium tartrate, bismuth sulfate, bismuth chloride, bismuth oxide, trioxide Examples include arsenic, potassium phosphate, sodium phosphate, potassium pyrophosphate, potassium hypophosphite, sodium phosphite, sodium tellurate, tellurium oxide, tellurium chloride, tellurite, potassium odorate, potassium iodide, etc. These may be one kind or a mixture of two or more kinds. Furthermore, it is not limited to these chemicals as long as it is soluble in an aqueous solution. Also, in order to solubilize in aqueous solution, acids such as sulfuric acid and hydrochloric acid, alkalis such as potassium hydroxide and sodium hydroxide, and chelating agents such as ethylenediaminetetraacetic acid (EDTA) and sodium nitrilotriacetate (NTA) May be used in a suitable mixture. Selected from the group consisting of Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, I The concentration of the soluble compound containing at least one kind is preferably 5 mg / L to 10 g / L. More preferably, it is 10-1000 mg / L. If the soluble compound concentration is less than 5 mg / L, the light reflectance of the silver plating film is lowered, which is not preferable. On the other hand, if the soluble compound concentration is 10 g / L or more, the light absorptivity of the silver plating film increases and the light reflectance decreases, which is not preferable.

  In addition, various surfactants may be added to the silver plating solution of the present invention in order to prevent unevenness of the silver plating film. For example, examples of the surfactant include nonionic surfactants such as polyoxyalkyl ether condensates.

  Furthermore, a pH buffering agent for stabilizing the pH may be added to the silver plating solution of the present invention. For example, examples of the pH buffer include boric acid, potassium metaborate, and phthalic acid.

  Using an electrically conductive lead frame or substrate as an anode, metallic silver, stainless steel, platinum group metal or titanium coated with a platinum group metal as a cathode, the anode and the cathode are immersed in the silver plating solution of the present invention, A plating method for performing electroplating on the lead frame or the substrate is possible.

  The silver plating solution of the present invention is a manual or automatic elevator type rack type plating method, a reel-to-reel type electroplating bath of an overflow type plating method, or a jet type plating method employed for partial plating of lead frames. Any of them can be supported.

  Although the liquid temperature which performs silver plating changes with the flow rates and stirring state of each plating apparatus, 15 to 70 degreeC is preferable in general. In the case of rack type plating or overflow type plating, the liquid temperature is preferably 20 to 30 ° C, and in the case of jet flow type plating, the liquid temperature is preferably 50 to 70 ° C.

The cathode current density for silver plating varies depending on the flow rate and stirring state of the plating apparatus. In rack type plating or overflow type plating, the cathode current density is preferably 1 to 5 A / dm ² , and in the case of jet flow type plating, the cathode current density is preferably 30 to 150 A / dm ² .

  Further, the lead frame after silver plating with the silver plating solution of the present invention can be plastically deformed by rolling or the like.

  According to the silver plating solution according to the present embodiment, it is possible to stabilize the mounting reliability, light reflection characteristics and corrosion resistance (particularly corrosion resistance against sulfidation corrosion) with respect to the lead frame or substrate for an optical semiconductor device. The characteristics can be improved.

  EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

  The LED of this example is manufactured as follows.

  As the lead frame, a copper alloy KLF194 (CDA No. C19400, iron content rate 2.3%) made by Kobe Steel Co., Ltd. with a thickness of 0.11 mm was used, and Enomoto's LED open frame FLASH Use the LED 6PIN OP1 (external dimension 5050) type that has been punched out. After degreasing with an alkaline degreasing agent, acid neutralization with dilute sulfuric acid is performed, and then copper plating is applied in a thickness of 0.5 μm with a cyan bath. Thereafter, the cathode current density and plating time are adjusted so as to obtain a film thickness of 3 μm with the silver plating solution of the present invention, silver plating is performed, the substrate is washed with clean pure water, dried, and lead with silver plating is provided. Make a lemma. In addition, silver plating shall be whole surface silver plating. The lead frame is placed in a mold, polyphthalamide resin is injected as a molding material, cured, and removed from the mold. Then, the blue light emitting diode chip is placed on the lead frame after the resin molding via the resin paste, and then heated and bonded at 150 ° C. for 1 hour. Thereafter, the electrode of the light emitting diode chip and the lead frame are connected with a gold wire having a diameter of 25 μm. Next, a 20% blend of YAG phosphor in a modified silicone resin is filled into the molding opening and cured with a hot air dryer (curing conditions: 150 ° C., 4 hours) to complete sealing. To do. Then, it cut | disconnects as individual LED.

  After the LED manufactured as described above is processed under the following two conditions, the total luminous flux φv (lm) is measured by an integral type total luminous flux measuring apparatus.

  The first test is a high-temperature operation test, in which the manufactured LED is placed in a 120 ° C. hot air thermostatic device, a current of 50 mA is passed, and processing is performed for 1000 hours. The second test is a corrosion test in accordance with JIS C60068-2-43, which is treated for 300 hours under a corrosion condition of 40 ° C., hydrogen sulfide gas 15 ppm, 80% RH.

  In this test, no failure mode such as wire bonding failure, die bonding failure, and resin adhesion failure occurs in all LEDs.

  Table 1 shows an example using the silver plating solution of the present invention and a comparative example using a conventional silver plating solution. Table 2 shows the measured values of the initial total luminous flux φv (lm) of the LED having the lead frame plated with the silver plating solutions of the examples and comparative examples of Table 1, and after the high temperature operation test and the corrosion test treatment. The measured value of the total luminous flux φv (lm) and the luminous flux fluctuation rate (%) are shown.

  As shown in Table 2, in Comparative Examples 1 and 2, the luminous flux is greatly reduced in each test, whereas Ti, Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga , Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and an optical semiconductor device obtained from a silver plating solution to which a soluble compound containing at least one selected from the group consisting of I is added In each test, the decrease in luminous flux is slight, and it can be seen that high light reflectance is maintained.

Claims (9)

  A silver plating solution containing 20 to 250 g / L of a silver cyanide complex, 50 to 200 g / L of a free cyanate salt, selenium compound and sulfur compound is added to Ti, Zr, V, Mo, W, Co, Pd. A soluble compound comprising at least one selected from the group consisting of Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, and I An electrolytic silver plating solution for an optical semiconductor device lead frame or substrate, which is added in a concentration range of 10 g / L and has a pH of 10 to 14.   In a silver plating solution containing at least one of silver cyanide complex 20 to 250 g / L, electric conduction salt 50 to 250 g / L, free cyanate 0.1 to 30 g / L, selenium compound and sulfur compound, Ti, At least one selected from the group consisting of Zr, V, Mo, W, Co, Pd, Au, Cu, Zn, Ga, Ge, In, Sn, Tl, Sb, Bi, As, P, Te, Br, I An electrolytic silver plating solution for a lead frame or substrate for an optical semiconductor device, wherein a soluble compound containing a seed is added in a concentration range of 5 mg / L to 10 g / L, and the pH is 7.5 to 14.   The lead frame or substrate for an optical semiconductor device according to claim 1 or 2, wherein the silver cyanide complex contains at least one selected from the group consisting of silver cyanide, silver potassium cyanide, and sodium silver cyanide. Electrolytic silver plating solution.   3. The electrolytic silver plating solution for a lead frame or a substrate for an optical semiconductor device according to claim 1, wherein the free cyanate salt contains at least one selected from the group consisting of potassium cyanide and sodium cyanide.   3. The optical semiconductor device according to claim 1, wherein the selenium compound contains at least one selected from the group consisting of potassium selenium cyanide, selenium cyanide, selenious acid, potassium selenium oxide, and selenium oxide. Electrolytic silver plating solution for lead frames or substrates.   3. The sulfur compound according to claim 1, wherein the sulfur compound contains at least one selected from the group consisting of carbon disulfide, thiourea, thiolactic acid, thiouracil, thiobarbituric acid, cysteine, cystine, thioacetic acid, and mercaptobenzothiazole. Electrolytic silver plating solution for lead frames or substrates for optical semiconductor devices.   As the sulfur compound, at least one compound selected from the group consisting of carbon disulfide, thiourea, thiolactic acid, thiouracil, thiobarbituric acid, mercaptobenzothiazole, cysteine, cystine, thioacetic acid, mercaptobenzothiazole, aliphatic or 3. An electrolytic silver plating solution for a lead frame or substrate for an optical semiconductor device according to claim 1, which contains a reaction product with an aromatic organic substance.   3. The electrolytic silver plating solution for a lead frame or a substrate for an optical semiconductor device according to claim 2, which contains at least one selected from the group consisting of phosphate, nitrate, citrate, and tartrate as the electrically conductive salt.   9. The anode and the cathode according to any one of claims 1 to 8, wherein an electrically conductive lead frame or substrate is used as an anode, metal silver, stainless steel, platinum group metal or titanium coated with a platinum group metal is used as a cathode. A plating method in which the lead frame or the substrate is electroplated by being immersed in the electrolytic silver plating solution according to the item.