JP5578960B2 - Lead frame for optical semiconductor device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical semiconductor device lead frame and a method of manufacturing the same.

  2. Description of the Related Art Conventionally, lead frames for optical semiconductor devices have been widely used as various display / illumination light sources using light emitting elements, which are optical semiconductor elements such as LED (Light Emitting Diode) elements, as light sources. In an optical semiconductor device, for example, after a lead frame is arranged on a substrate and a light emitting element is mounted on the lead frame, the light source and its surroundings are prevented in order to prevent deterioration of the light source element and its peripheral part due to heat, moisture, oxidation, etc. It is manufactured by sealing the periphery with resin.

  As a lead frame for an optical semiconductor device, a method has been proposed in which a silver plating layer excellent in light reflection characteristics, that is, light reflectivity, is formed in the vicinity of a reflector near the reflector on which a semiconductor light emitting element is mounted. (For example, refer to Patent Document 1). However, silver reacts with the sulfur component in the atmosphere or in the sealing resin to cause black discoloration and may reduce the reflectance.

  Therefore, in order to improve the corrosion resistance, 0.005 to 0.15 μm of palladium is formed on the nickel underlayer and 0.003 to 0.05 μm of rhodium is formed on the outermost layer without using silver for the coating layer of the lead frame. Has been proposed (see, for example, Patent Document 2). However, the coating layer with this configuration may have a significantly reduced reflectance in the visible light region as compared with the case where silver is used for the coating layer, and it is difficult to apply to applications requiring high luminance. . Further, rhodium has poor wire bonding and solder wettability, and it cannot be said that connection reliability is high. Furthermore, rhodium is particularly expensive among noble metals, and there is concern about the supply stability, and it is difficult to supply an optical semiconductor device at a low price.

  Therefore, a method of manufacturing a lead frame for an optical semiconductor device by providing a very thin coating with excellent corrosion resistance on silver or a silver alloy has been proposed. For example, Patent Document 3 and Patent Document 4 propose a technique for improving corrosion resistance by providing a gold-silver alloy plating layer or a characteristic maintaining layer on an upper layer of silver or a silver alloy.

However, since silver and gold are very easy to diffuse, silver is often easily exposed on the outermost surface of the lead frame from the alloy plating layer of gold and silver. In particular, due to the heat generated when an optical semiconductor element is mounted on a lead frame, silver is easily exposed on the surface from the gold-silver alloy plating layer, discolors in the same way as silver, and the reflectance decreases. There is.
In addition, when an organic film or a silicone film is formed as the characteristic maintaining layer, it is difficult to ensure wire bonding after the light emitting element is mounted. Further, the portion exposed to the outside of the sealing resin is connected to the wiring board by soldering. At this time, the diffusion of silver proceeds due to heat generated when the optical semiconductor device is formed, and soldering may not be possible due to oxidation or sulfuration of silver on the outermost surface. For this reason, after manufacturing the optical semiconductor device, it is necessary to perform extrapolation plating in which the terminal portion of the product is newly subjected to processing such as tin plating. This method increases the number of manufacturing processes, which not only hinders the provision of an optical semiconductor device at a low price, but also may cause the optical semiconductor device to fail during extrapolation plating, and an improvement is desired. It was.

Japanese Patent Laid-Open No. 61-148883 JP 2005-129970 A JP 2008-91818 A JP 2009-135355 A

  It is an object of the present invention to provide a lead frame for an optical semiconductor device having excellent light reflectivity and high brightness, and a method for manufacturing the lead frame. Another object of the present invention is to provide a lead frame for an optical semiconductor having excellent long-term reliability and wire bonding property, and excellent solderability at a portion exposed to the outside, and a method for manufacturing the same.

  As a result of intensive studies in view of the above problems, a reflective layer made of silver or a silver alloy is formed on the substrate, a corrosion-resistant film layer made of a specific metal or alloy is formed on the reflective layer, and a specific layer is formed on the corrosion-resistant film layer. It has been found that a lead frame for an optical semiconductor device in which the outermost layer made of the above metal or alloy is formed at least at a location where wire bonding is applied is excellent in reflectance characteristics, corrosion resistance, wire bonding properties and solderability. The present invention has been made based on this finding.

That is, the present invention
(1) A lead frame for an optical semiconductor device in which wire bonding is performed on a substrate, wherein a reflective layer made of silver or a silver alloy is formed on the substrate, and the group made of indium and an indium alloy is formed on the reflective layer A corrosion-resistant film layer made of a metal or alloy selected from 0.005 to 0.2 μm in thickness is formed on the corrosion-resistant film layer, and gold, platinum, a gold alloy containing no silver, and a platinum alloy containing no silver A lead for an optical semiconductor device, wherein an outermost layer made of a metal or alloy selected from the group consisting of: a thickness of 0.001 to 0.05 μm is formed at least at a position where the wire bonding is performed. flame,
(2) The lead frame for an optical semiconductor device according to (1), wherein the reflective layer has a thickness of 0.2 to 5.0 μm.
(3) At least one intermediate layer made of a metal or alloy selected from the group consisting of nickel, nickel alloy, cobalt, cobalt alloy, copper, and copper alloy is formed between the base and the reflective layer. A lead frame for an optical semiconductor device according to item (1) or (2),
(4) A method of manufacturing a lead frame for an optical semiconductor device in which wire bonding is performed on a substrate, wherein a reflective layer made of silver or a silver alloy is formed on the substrate by electroplating, and the reflective layer is formed on the reflective layer A corrosion-resistant film layer having a thickness of 0.005 to 0.2 μm made of a metal or alloy selected from the group consisting of indium and an indium alloy is formed by electroplating, and contains gold, platinum, and silver on the corrosion-resistant film layer An outermost layer having a thickness of 0.001 to 0.05 μm made of a metal or alloy selected from the group consisting of a gold alloy, a platinum alloy containing no silver, and at least where the wire bonding is performed by electroplating And (5) nickel, nickel alloy, cobalt, cobalt alloy, copper between the base and the reflective layer. And an intermediate layer made of a metal or alloy selected from the group consisting of a copper alloy is formed by electroplating, the method for producing a lead frame for an optical semiconductor device according to (4),
Is to provide.

In the lead frame for an optical semiconductor device of the present invention, a reflective layer made of silver or a silver alloy is formed on a substrate, and a corrosion-resistant film layer made of a specific metal or alloy is formed on the reflective layer with a specific thickness. Therefore, it is possible to improve the corrosion resistance (especially corrosion resistance against sulfidation corrosion) while taking advantage of the excellent reflection characteristics of silver, to suppress silver migration and to suppress the discoloration of silver and to maintain excellent solderability. can do.
Furthermore, the lead frame for an optical semiconductor device of the present invention is formed by forming an outermost layer made of a specific metal or alloy on a corrosion-resistant film layer at a specific thickness at least at a place where wire bonding is performed, thereby obtaining silver or a silver alloy It is possible to ensure the excellent light reflectivity of the optical fiber at a high level at a wavelength of 400 to 800 nm, suppress an error in wire bonding of an optical semiconductor, and have stable wire bonding properties.
Further, according to the manufacturing method of the present invention, the thickness of each coating layer can be easily controlled, and the productivity is excellent. Therefore, a lead frame for an optical semiconductor device having a desired coating layer thickness is manufactured. be able to. With the manufacturing method of the present invention, it is suitable as a lead frame for optical semiconductor devices used for LEDs, photocouplers, photointerrupters, etc., and has good reflection characteristics from 400 nm to 800 nm in the near infrared region, and further has corrosion resistance. A lead frame excellent in (particularly corrosion resistance against sulfidation corrosion), long-term reflectance stability, and wire bonding property can be manufactured.

1 is a schematic cross-sectional view of a first embodiment of a lead frame for an optical semiconductor device according to the present invention. It is a schematic sectional drawing of the 2nd embodiment of the lead frame for optical semiconductor devices which concerns on this invention. It is a schematic sectional drawing of the 3rd embodiment of the lead frame for optical semiconductor devices which concerns on this invention.

FIG. 1 is a schematic sectional view of a first embodiment of a lead frame for optical semiconductor devices according to the present invention. However, FIG. 1 shows a state in which the optical semiconductor chip 5 and the wire bonding 6 are formed on the lead frame (the same applies to FIGS. 2 and 3 below).
As shown in FIG. 1, in the lead frame of the first embodiment, a reflective layer 2 made of silver or a silver alloy is formed on a substrate 1, and the reflective layer 2 is selected from the group consisting of indium and an indium alloy. The outermost layer is made of a metal or alloy selected from the group consisting of gold, platinum, a gold alloy containing no silver, and a platinum alloy containing no silver. 4 is formed on the entire surface. In the present invention, the thickness of the corrosion-resistant film 3 is 0.005 μm or more and 0.2 μm or less, and the thickness of the outermost layer 4 is 0.001 μm or more and 0.05 μm or less. The present invention provides a lead frame for an optical semiconductor device that has excellent reflection characteristics in the visible light wavelength range of 400 to 800 nm, excellent corrosion resistance (particularly corrosion resistance against sulfidation corrosion), migration resistance, and wire bonding properties. Can do.

As the substrate 1 of the lead frame for optical semiconductor devices of the present invention, for example, copper or copper alloy, iron or iron alloy, aluminum or aluminum alloy, etc. are preferably used.
Among the substrates, examples of the copper alloy include C19400 (Cu-Fe based alloy material: for example, Cu-2.3Fe-0.03P-0.15Zn), C26000 as examples of CDA (Copper Development Association) standard alloys. (Brass: Cu-30Zn), C26800 (Brass: Cu-35Zn), C52100 (Phosphor Bronze: Cu-8Sn-P), C77000 (Western White: Cu-18Ni-27Zn). Also, CDA standard alloys C14410 (Cu-0.15Sn: EFTEC-3 manufactured by Furukawa Electric Co., Ltd.), C18045 (Cu-0.3Cr-0.25Sn-0.2Zn-based alloy: EFTEC-64T manufactured by the same company) C52180 (Cu-8Sn-0.1Fe-0.05Ni-0.04P: F52218 made by the company), C70250 (Cu-3.0Ni-0.65Si-0.15Mg: EFTEC-7025 made by the company), etc. are also suitable. Take as an example.
Examples of the iron alloy in the substrate include stainless steel (SUS301, SUS304, SUS401) stipulated by Japanese Industrial Standard (JIS G 4305: 2005) and 42 alloy (Fe-42% Ni) that is an Fe—Ni alloy. ) And the like.
Among the substrates, examples of the aluminum alloy include A1100, A2014, A3003, A5052 and the like defined in Japanese Industrial Standards (JIS H 4000: 2006, etc.).

  On these substrates, it is easy to form a reflective layer and an outermost layer film, and a lead frame with good productivity can be provided. In addition, the lead frame based on these metals has excellent heat dissipation characteristics, and the heat energy generated when the light emitting element emits light can be smoothly discharged to the outside through the lead frame, so that the long life of the light emitting element is achieved. And stabilization of reflectance characteristics over a long period is expected. Since this depends on the conductivity of the substrate, for example, it is preferably 10% IACS (International Annealed Copper Standard) or more, and more preferably 50% IACS or more. Iron alloy SUS304, etc. and 42 alloy are generally less than 10% IACS, but suitable for applications that require strength as a lead frame, applications that do not require strong heat dissipation, and general-purpose LED applications. Can be used.

  The plate thickness and the plate width of the conductive substrate are not particularly limited, but the lead frame size in the LED is generally 0.05 to 1.0 mm and the plate width is about 10 to 200 mm. The optical semiconductor device lead frame can satisfy various characteristics at least in the above size.

  The thickness of the reflective layer 2 made of silver or a silver alloy is preferably 0.2 to 5.0 μm, more preferably 0.5 to 4.0 μm, and more preferably 1.0 to 3.0 μm. If the thickness of the pure silver layer is too thin, the thickness contributing to the reflectivity is not sufficient. For this reason, the thickness of the reflective layer 2 made of silver or a silver alloy is preferably 0.2 μm or more from the viewpoint of long-term reliability. If the thickness of the reflective layer 2 becomes too thick, the effect is saturated and the cost is increased, and cracking is likely to occur during pressing. By setting the coating thickness of the reflective layer 2 within the above range, a lead frame for an optical semiconductor device can be manufactured at a low cost without using an excessive amount of noble metal.

  Examples of silver or silver alloy forming the reflective layer 2 include silver, silver-tin alloy, silver-indium alloy, silver-rhodium alloy, silver-ruthenium alloy, silver-gold alloy, silver-palladium alloy, silver-nickel. An alloy, a silver-selenium alloy, a silver-antimony alloy, or a material selected from the group of silver-platinum alloys can be used. As a result, a lead frame with good reflectivity and good productivity can be obtained.

Further, in FIG. 1, an anticorrosion film 3 made of either indium or indium alloy is formed on the upper layer of the reflective layer 2 with a thickness of 0.005 μm to 0.2 μm. The corrosion-resistant coating 3 can ensure long-term reliability of the reflective layer 2 made of silver or a silver alloy, and can improve solder wettability when the reflective layer 2 is exposed as an external terminal. The anticorrosion film 3 can prevent the reflective layer 2 from reacting with sulfur and discoloring black. In particular, as the corrosion-resistant film 3, a metal or alloy selected from the group consisting of indium and an indium alloy is used as a film that is a white metal that does not easily reduce the reflectance of light and has excellent corrosion resistance. Among these, indium is particularly preferable. If the thickness of the corrosion-resistant film 3 is too thin, the corrosion resistance becomes insufficient. On the other hand, if the thickness of the corrosion-resistant film 3 is too thick, the light reflectance of the reflective layer cannot be effectively used. It is important to control at 0.005 μm to 0.2 μm. By controlling in this range, effective corrosion resistance and reflection characteristics can be maintained. In order to achieve both corrosion resistance and reflection characteristics, the thickness of the corrosion-resistant coating 3 is more preferably controlled to 0.01 to 0.1 μm.

Further, in FIG. 1, an outermost layer 4 made of a metal or alloy selected from the group consisting of gold, platinum, a gold alloy not containing silver, and a platinum alloy not containing silver is formed on the corrosion-resistant film 3 with a thickness of 0. It is formed at least at a location where wire bonding is performed at 001 μm or more and 0.05 μm or less. Since the surface layer of the corrosion-resistant film 3 is easy to form an oxide film, stable bonding properties cannot be maintained if the outermost layer is a corrosion-resistant film. For this reason, stable wire-bonding property is securable by providing an outermost layer on a corrosion-resistant film. In order to ensure stable wire bonding and prevent a decrease in reflectivity as much as possible, the outermost layer 4 is a metal selected from the group consisting of gold, platinum, a gold alloy not containing silver, and a platinum alloy not containing silver, or Use an alloy. As the outermost layer 4, gold or platinum is particularly preferable.
The coating thickness of the outermost layer 4 is 0.001 μm or more and 0.05 μm or less. If the thickness of the outermost layer is too thin, the reliability of the wire bonding property is lowered. On the other hand, if the thickness of the outermost layer is too thick, the light reflectance is lowered. For this reason, it is important that the thickness of the outermost layer be 0.001 μm to 0.05 μm. By making the thickness of the outermost layer within this range, effective wire bonding properties can be ensured. From the viewpoint of preventing reflectance reduction, the thickness of the outermost layer is more preferably 0.005 μm to 0.02 μm.

  If the thickness of the outermost layer 4 is within the above range, the number of layers is not particularly limited. For example, the Au layer can be 0.005 μm, and the Pt layer can be 0.005 μm on the Au layer. However, in consideration of productivity, cost, etc., it is preferably within 2 layers.

FIG. 2 is a schematic cross-sectional view of a second embodiment of the lead frame for optical semiconductor devices according to the present invention. The lead frame of the embodiment shown in FIG. 2 is different from the lead frame shown in FIG. 1 in that an intermediate layer 7 is formed between the base 1 and the reflective layer 2. Other points are the same as those of the lead frame shown in FIG.
As shown in FIG. 2, between a base 1 and a reflective layer 2 made of silver or a silver alloy, a metal or alloy selected from the group consisting of nickel, nickel alloy, cobalt, cobalt alloy, copper, and copper alloy is used. At least one intermediate layer 7 is formed. Thereby, it is possible to prevent the deterioration of the reflectance characteristic due to the diffusion of the material constituting the substrate into the reflective layer by the heat generated when the light emitting element emits light, and to stabilize the reflectance characteristic over a long period of time. Further, by providing the intermediate layer 7, the adhesion between the base and the reflective layer made of silver or a silver alloy can be improved. The thickness of the intermediate layer is determined in consideration of cost, in addition to productivity and heat resistance including ease of pressing during production. The total thickness of the intermediate layers is preferably 0.2 to 5.0 μm, more preferably 0.2 to 2.0 μm, and particularly preferably 0.5 to 2.0 μm.
It is also possible to form the intermediate layer with a plurality of layers. Usually, in consideration of productivity, it is preferable to have two layers or less.

FIG. 3 is a schematic cross-sectional view of a third embodiment of the lead frame for optical semiconductor devices according to the present invention. The difference from the lead frame shown in FIG. 2 is that the outermost layer 4 is partially formed only in the vicinity of the wire bonding 6. The other points are the same as those of the lead frame shown in FIG.
The lead frame of the present invention has an optical semiconductor chip 5 mounted thereon, and external wiring is appropriately connected by wire bonding 6 so that electric power is supplied from the outside to the optical semiconductor chip 5. (For example, region A in FIG. 3) is molded with resin to form an optical semiconductor device.
The formation place of the outermost layer 4 needs to be formed at least at the place where the wire bonding 6 is applied. In other words, the outermost layer 4 does not have to be formed other than where the wire bonding 6 is applied. Since the anti-discoloration of the reflective layer 2 acting as a reflective plate is maintained by the corrosion-resistant coating 3, for example, in the portion where the bonding is not formed even inside the resin mold, the outermost layer 4 is not formed. Good. For this reason, the outermost layer 4 may be formed partially, for example, may be formed by partial plating such as stripe plating or spot plating. By partially forming the outermost layer, it is possible to reduce the amount of metal used in unnecessary portions, reduce the influence on the environment, and provide an optical semiconductor lead frame at low cost.

  As shown in FIG. 3, in the region not resin-molded (for example, region B in FIG. 3), the corrosion-resistant coating 3 appears on the outermost surface, the discoloration of silver is suppressed, and it has good solder wettability. Therefore, excellent solder wettability can be maintained over a long period of time. Therefore, it is possible to provide a lead frame for an optical semiconductor that exhibits excellent solderability even after the optical semiconductor device is formed without performing a process such as extrapolation plating.

  It should be noted that any method can be used as a method for manufacturing a lead frame for an optical semiconductor device in the present invention. The reflective layer 2, the corrosion resistant film 3, the outermost layer 4 and the intermediate layer 7 are preferably formed by electroplating. The electroplating method can easily adjust the thickness as compared with the clad method and the sputtering method, and can provide a lead frame at a low price.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to this.

Thickness 0.25 mm, after the following pretreatment was performed on the substrate shown in Table 1 of width 50 mm, by performing the following electroplating process on the substrate whole surface, the present invention of the configuration shown in Table 1 from 1 to 29, Reference Lead frames of Examples 1 to 10, Conventional Examples 1 to 3, and Comparative Examples 1 to 7 were obtained. In Reference Example 10 , the gold layer was formed to 0.0025 μm, then the platinum layer was formed to 0.0025 μm, and the outermost layer was formed in total to 0.005 μm.

  Of the materials used for the substrate, “C19400” and “C18045 (EFTEC-64)” indicate a copper or copper alloy substrate, and the numerical value after C indicates the type according to the CDA (Copper Development Association) standard. “C18045 (EFTEC-64T)” is a copper alloy manufactured by Furukawa Electric Co., Ltd.

  As pretreatment, the following electrolytic degreasing and then the following pickling were performed. In addition, before forming a pure silver plating layer, silver strike plating was performed with a thickness of 0.01 μm.

The pretreatment conditions are shown below.
(Pretreatment conditions)
[Electrolytic degreasing]
Degreasing solution: NaOH 60 g / liter Degreasing conditions: 2.5 A / dm ² , temperature 60 ° C., degreasing time 60 seconds [pickling]
Pickling solution: 10% sulfuric acid pickling condition: 30 seconds immersion, room temperature [Ag strike plating] coating thickness 0.01 μm
Plating solution: KAg (CN) ₂ 5 g / liter, KCN 60 g / liter,
Plating conditions: current density 2 A / dm ² , plating time 4 seconds, temperature 25 ° C.

The plating solution composition and plating conditions for each plating used are shown below.
(Middle layer)
[Cu plating]
Plating solution: CuSO ₄ .5H ₂ O 250 g / liter, H ₂ SO ₄ 50 g / liter, NaCl 0.1 g / liter Plating condition: current density 6 A / dm ² , temperature 40 ° C.
[Ni plating]
Plating _{solution: Ni (SO 3 NH 2)} 2 · 4H 2 O 500g / l, NiCl ₂ 30 g / _l, H ₃ BO ₃ 30g / l Plating Conditions: current density 5A / dm ^2, temperature 50 ° C.
[Co plating]
Plating _{solution: Co (SO 3 NH 2)} 2 · 4H 2 O 500g / l, CoCl ₂ 30 g / _l, H ₃ BO ₃ 30g / l Plating Conditions: current density 5A / dm ^2, temperature 50 ° C.

(Reflective layer)
[Ag plating]
Plating solution: AgCN 50 g / liter, KCN 100 g / liter, K ₂ CO ₃ 30 g / liter Plating condition: current density 1 A / dm ² , temperature 30 ° C.
[Rh plating]
Plating solution: RHODEX (trade name, manufactured by Nippon Electroplating Engineers Co., Ltd.)
Plating conditions: 1.3 A / dm ² , temperature 50 ° C.

(Corrosion resistant coating)
[In plating]
Plating solution: InCl ₃ 45 g / liter, KCN 150 g / liter, KOH 35 g / liter, dextrin 35 g / liter Plating conditions: current density 2 A / dm ² , temperature 20 ° C.
[Sn plating]
Plating solution: SnSO ₄ 80 g / liter, H ₂ SO ₄ 80 g / liter Plating condition: current density 2 A / dm ² , temperature 30 ° C.
[Pd plating]
Plating solution: Pd (NH ₃ ) ₂ Cl ₂ 45 g / liter, NH ₄ OH 90 ml / liter, (NH ₄ ) ₂ SO ₄ 50 g / liter Plating condition: current density 1 A / dm ² , temperature 30 ° C.

(Outermost layer)
[Au plating]
Plating solution: KAu (CN) ₂ 14.6 g / liter, C ₆ H ₈ O ₇ 150 g / liter, K ₂ C ₆ H ₄ O ₇ 180 g / liter Plating condition: current density 1 A / dm ² , temperature 40 ° C.
[Pt plating]
Plating solution: Pt (NO ₂ ) ₂ (NH ₃ ) ₂ 10 g / liter, NaNO ₂ 10 g / liter, NH ₄ NO ₃ 100 g / liter, NH ₃ 50 ml / liter Plating conditions: current density 5 A / dm ² , temperature 90 ℃
[Pd plating]
Plating solution: Pd (NH ₃ ) ₂ Cl ₂ 45 g / liter, NH ₄ OH 90 ml / liter, (NH ₄ ) ₂ SO ₄ 50 g / liter Plating condition: current density 1 A / dm ² , temperature 30 ° C.

The obtained lead frames of the present invention examples, reference examples, comparative examples, and conventional examples were subjected to the following tests and their performance was evaluated according to the following criteria.
(1) Reflectivity: In a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, trade name: U-4100), continuous measurement was carried out with a total reflectance of 400 nm to 800 nm. Of these, the reflectance (%) at 400 nm, 600 nm, and 800 nm is shown in Table 2. Here, a reflectance of 70% or more at a wavelength of 400 nm to 800 nm was judged as a practical level.
(2) Corrosion resistance evaluation: As an evaluation of corrosion resistance, after conducting atmospheric heating at 150 ° C. for 3 hours as a heat history assuming a resin molding process, a sulfurization test (described in JIS H8502), H ₂ S 3 ppm, reflection after 24 h Evaluation was made on rate change. The results are shown in Table 2. Here, it was determined that the long-term reliability was good because the reflectance at a wavelength of 400 nm to 800 nm was maintained at 70% or more as a level with good corrosion resistance.
(3) Wire bonding property (WB property): After performing atmospheric heating at 150 ° C. for 3 hours as a heat history assuming a resin molding process, under the following wire bonding conditions, bond strength measurement is performed after a 10-point test, When the value of (strength-3σ) is 29.4 mN or more, it is judged as “excellent”, and “◎” is marked on the table, and those that are less than 29.4 mN but can be joined without error are “good”. The table is marked with “O”, and even if one point has an error or is not joined at all, it is judged as “impossible”, and the table is marked with “X”, respectively. It was shown to.
Wire bonder: SWB-FA-CUB-10, manufactured by Shinkawa Co., Ltd. Wire: 25 μm Gold wire Bonding temperature: 150 ° C.
Capillary: 1570-15-437GM
1st condition: 10 msec. , 45Bit, 45g
2nd condition: 10 msec. , 100bit, 130g
The practical level was judged as an evaluation result of “◯” or higher.
(4) Solderability: After performing atmospheric heating at 150 ° C. for 3 hours as a heat history assuming a resin molding process, and further performing the above sulfidation test for 24 hours, a solder checker (SAT-5100 (trade name, ( Solder wetting time was evaluated using Resca Co., Ltd.). The details of the measurement conditions are as follows. If the solder wetting time is less than 3 seconds, it is determined to be “excellent”. It was determined that there was a “◯” mark, and those that were not joined even after being immersed for 10 seconds were determined as “impossible” and marked with an “X” mark.
Solder type: Sn-3Ag-0.5Cu
Temperature: 250 ° C
Flux: isopropyl alcohol-25% rosin Immersion speed: 25 mm / sec.
Immersion time: 10 seconds Immersion depth: 10 mm
The practical level was judged as an evaluation result of “◯” or higher.

Each thickness of the intermediate layer, the corrosion-resistant film, and the outermost layer shown in Table 1 is an average value (arbitrary value) measured using a fluorescent X-ray film thickness measuring device (SFT 9450: product name, manufactured by SII Nanotechnology). (Arithmetic average of 10 measured values).
As is apparent from the results shown in Table 2, for example, in a lead frame for optical semiconductors in which a reflective layer made of silver or a silver alloy is provided on copper or a copper alloy such as C19400, C18045, etc., the upper layer is made of indium, an indium alloy, A corrosion resistance film made of tin or a tin alloy is provided within a specific thickness range, and a specific metal or alloy is provided as an uppermost layer with a specific thickness on the upper layer, the reflectivity at 400 nm to 800 nm However, it is understood that 70% or more can be maintained in the entire region in the initial stage and 70% or more can be maintained even after the sulfidation test.

On the other hand, as shown in Conventional Example 1, when the corrosion-resistant film and the outermost layer are not provided, the initial reflectance is very high and shows excellent characteristics, but after the sulfidation test, in the entire range of 400 to 800 nm. It can be seen that the reflectivity is 50% or less, and that long-term reliability is applied. Also, in the solder wetting test after heat treatment at 150 ° C. for 3 hours, which is a heat treatment simulating a resin mold process, and after performing a sulfidation test for 24 hours, in the case of Conventional Example 1, solder wetting cannot be ensured due to sulfidation discoloration. It was.
Further, in Conventional Example 3 in which gold plating was applied as the outermost layer without providing a corrosion-resistant film, the lower layer of silver reached the outermost layer by heating and caused sulfur discoloration. For this reason, the reflectance decreased at 400 nm to 800 nm, and the solder wettability could not be ensured.
Furthermore, in Conventional Example 2 in which rhodium plating was applied as the reflective layer and the corrosion-resistant film and the outermost layer were not provided, the reflectance was 70% or higher in the entire region from 400 nm to 800 nm after the initial stage and after the sulfidation test. It turns out that it is excellent in reliability, but it is inferior in wire bonding property, and solder wettability cannot be secured.

On the other hand, in Comparative Example 1 in which the corrosion-resistant film was too thin, discoloration after the sulfidation test could not be suppressed and the reflectance decreased, and the reflectance at a wavelength of 400 nm was less than 70%.
In Comparative Example 2 in which the corrosion-resistant film is too thick, the initial reflectance is less than 70% at 400 nm to 600 nm, indicating that the reflectance of the reflective layer cannot be utilized.
In Comparative Example 3 where the outermost layer was too thin, an error occurred in wire bonding, and it was found that the wire bonding property was insufficient.
In Comparative Example 4 where the outermost layer was too thick, the reflectance at a wavelength of 400 nm was less than 70%. For this reason, it is guessed that the brightness | luminance which was excellent in the LED chip which light-emits a wavelength of 400 nm cannot be obtained, for example.
In Comparative Example 5 where the outermost layer was not formed, it was found that wire bonding could not be performed and connection reliability was poor.
Moreover, in the comparative example 6 which formed the corrosion-resistant film | membrane with palladium, it is guessed that a reflectance is less than 70% in wavelength 400-600 nm, and the outstanding brightness | luminance cannot be obtained. This suggests that the reflectance is greatly reduced with palladium, and it is necessary to use either indium, tin, an indium alloy, or a tin alloy as a corrosion-resistant film excellent in reflectance.
Moreover, in the comparative example 7 which formed the outermost layer with palladium, it is guessed that the reflectance in wavelength 400nm is less than 70%, and the outstanding brightness | luminance cannot be obtained. Moreover, it is suggested that the bonding property is slightly worse than that of gold or platinum. This indicates that when palladium having a low reflectance is used, the reduction in reflectance is increased, and that gold or platinum is preferable in order to stably obtain bonding properties.

  As can be seen from these, the lead frame for an optical semiconductor device of the present invention has almost no deterioration in luminance because the initial reflectance is 70 nm or more at a wavelength of 400 nm to 800 nm and the reflection layer has excellent corrosion resistance. It can be seen that the wire bonding property and the solder wettability are excellent.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Reflective layer 3 Corrosion-resistant film 4 Outermost layer 5 Optical semiconductor chip 6 Wire bonding 7 Intermediate layer

Claims (5)

A lead frame for an optical semiconductor device in which wire bonding is performed on a substrate,
A reflective layer made of silver or a silver alloy is formed on the substrate, and a corrosion-resistant film layer made of a metal or alloy selected from the group consisting of indium and an indium alloy is formed on the reflective layer with a thickness of 0.005 to 0.2 μm. The outermost layer made of a metal or alloy selected from the group consisting of gold, platinum, a gold alloy containing no silver, and a platinum alloy containing no silver is formed on the corrosion-resistant film layer with a thickness of 0.001 to 0 A lead frame for an optical semiconductor device, characterized in that the lead frame is formed at a location where the wire bonding is performed at a thickness of .05 μm.   The lead frame for an optical semiconductor device according to claim 1, wherein the reflective layer has a thickness of 0.2 to 5.0 μm.   At least one intermediate layer made of a metal or alloy selected from the group consisting of nickel, nickel alloy, cobalt, cobalt alloy, copper, and copper alloy is formed between the base and the reflective layer. 3. The lead frame for an optical semiconductor device according to claim 1, wherein the lead frame is an optical semiconductor device. A method of manufacturing a lead frame for an optical semiconductor device in which wire bonding is performed on a substrate, wherein a reflective layer made of silver or a silver alloy is formed on the substrate by electroplating, and indium and indium are formed on the reflective layer. A gold alloy that does not contain gold, platinum, or silver on a corrosion-resistant coating layer formed by electroplating a corrosion-resistant coating layer having a thickness of 0.005 to 0.2 μm made of a metal selected from the group consisting of alloys or alloys. Forming an outermost layer having a thickness of 0.001 to 0.05 μm made of a metal or alloy selected from the group consisting of platinum alloys not containing silver by an electroplating method at least at a place where the wire bonding is performed. A method for manufacturing a lead frame for an optical semiconductor device. An intermediate layer made of a metal or alloy selected from the group consisting of nickel, nickel alloy, cobalt, cobalt alloy, copper, and copper alloy is formed between the base and the reflective layer by electroplating. A method for manufacturing a lead frame for an optical semiconductor device according to claim 4.

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