JP2012212850A - Lead frame for led and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame for LED including a reflection film that can accommodate wire bonding of an LED chip, can maintain high reflectance for a long term by applying a material of low cost in place of silver, and can be formed stably and easily.SOLUTION: The lead frame 1 includes a reflection film 13 having a thickness of 50 nm or more composed of aluminum or an aluminum alloy and formed on a substrate 11 composed of copper or a copper alloy, and a noble metal film 14 having a thickness of 5-50 nm consisting of one kind or more selected from Pd, Au, Pt and formed on the reflection film 13.

Description

  The present invention constitutes a light emitting device used for a backlight of a liquid crystal display, a lighting fixture, an automobile headlamp, a rear lamp, and the like, and is mounted with a light emitting diode (LED) chip (die) as a light source. The present invention relates to an LED lead frame connected by bonding and a manufacturing method thereof.

  2. Description of the Related Art In recent years, light emitting devices using LEDs as light sources have spread in a wide range of fields and applied to various devices by taking advantage of energy saving and long life. As an example of a light-emitting device using an LED as a light source, the structure and operation of a surface-mounted light-emitting device will be described with reference to FIG. 2A and 2B are external views of a surface-mounted light-emitting device using an LED chip as a light source, where FIG. 2A is a perspective view and FIG. 2B is a plan view (top view).

  As shown in FIGS. 2A and 2B, the light emitting device includes an LED chip and a pair of a positive electrode and a negative electrode that are electrically connected to the LED chip and supply a driving current to the LED chip. Lead members 1a and 1c and a support member 2 for supporting them. Specifically, the support member 2 is made of a resin molded body 21 that is an insulating material, and is formed with a concave LED chip mounting portion 22 in which the LED chip is accommodated. Is. The lead members 1 a and 1 c are formed in a band shape, and each penetrates from the outside of the support member 2 to the inside of the LED chip mounting portion 22.

  The LED chip is placed at substantially the center of the bottom surface of the LED chip mounting portion 22, and is fixed to the upper surface of one lead member 1a disposed at this position by an adhesive (not shown). Further, the electrodes (not shown) of the LED chip are connected to the pair of lead members 1a and 1c by bonding wires (wires). Further, the LED chip mounting portion 22 is sealed by being filled with a transparent sealing resin (not shown) such as an epoxy resin. That is, this light emitting device is a so-called package in which an LED chip is enclosed. In addition, “upper” in this specification indicates the side on which the LED chip of the lead frame is mounted in principle.

  Such a light emitting device is illustrated with the respective portions (referred to as outer lead portions (see FIG. 2B)) extending outside the support member 2 of the lead members 1a and 1c as electrodes of external terminals. Not used with an external power supply connected. Specifically, the light emitting device is mounted on a printed wiring board or the like, and the outer lead portions of the lead members 1a and 1c are electrically connected to the wiring by solder or the like. A drive current is supplied to the LED chip via the wiring of the wiring board and the lead members 1a and 1c, the LED chip emits light, and this light is emitted from the opening of the LED chip mounting portion 22 to the outside of the light emitting device. Specifically, the light emitting portion (light emitting layer) of the LED emits light by the drive current, and light is emitted around the light emitting portion to be irradiated from the LED chip in all directions.

  Of the light emitted from the LED chip, the light emitted upward is directly emitted from the opening of the LED chip mounting portion 22 to the outside of the light emitting device and used as illumination light or the like. However, the other light irradiated to the side and the lower side is incident on the side and bottom surfaces of the LED chip mounting portion 22 and the surfaces of the lead members 1a and 1c on the bottom surfaces. Therefore, the support member 2 and the lead members 1a and 1c are required to have high light reflectance (hereinafter referred to as reflectance) so that these surfaces reflect light incident from the LED chip well. . For example, the support member 2 is made of a resin molded body 21 made of a white resin, or a reflective film is formed on each surface of the LED chip mounting portion 22 (not shown). On the other hand, the lead members 1a and 1c are known to have excellent conductivity and have a reflective film formed on the surface of a common copper (Cu) or copper alloy as a lead frame material. As a material for such a reflective film, silver (Ag) is the most suitable for reflecting a lot of light with the highest reflectance among metals, and further has a wire bonding property for connecting LED chips. It is applied because it is good and the solderability for connecting to an external power source is as good as that of a copper substrate.

However, Ag reacts with the halogen ions and sulfur contained in the atmosphere and the sealing resin with the lapse of the usage time of the light emitting device, and thereby a halide or sulfide (Ag ₂ S) such as chloride (AgCl) is formed on the surface. Because of the formation, the surface of the reflective film is changed to blackish brown or aggregates due to these products, the surface is roughened, and Ag is also aggregated by the heat generated from the LED chip, so that the reflectance is deteriorated. There's a problem. In addition, when an epoxy resin is used as the sealing resin, Ag in the reflective film diffuses into the transparent epoxy resin and precipitates as Ag nanoparticles, and turns brown to deteriorate the light transmittance.

  In order to solve this problem, for example, in Patent Documents 1 and 2, a pure Ag plating layer is further coated with an Ag—Au alloy plating layer that is difficult to form chloride or sulfide, and chloroplatinic acid is used. A lead frame in which a silicone resin containing a metal chloride as a curing catalyst is applied to a sealing resin is described. Patent Documents 3 to 5 describe lead frames to which Ge and Bi are added and an Ag alloy film excellent in halogenation resistance, sulfidation resistance, and heat resistance is applied.

JP 2008-91818 A JP 2009-76948 A JP 2008-192635 A JP 2011-9707 A JP 2011-23704 A

  As described in these patent documents, it is possible to impart durability to Ag by adding a specific element, but such an element is added within a range where the reflectance is not impaired, etc. It is necessary to precisely control the components of the reflective film. Furthermore, in order to ensure sufficient wire bonding and to prevent discoloration of the surface due to diffusion of Cu from the substrate due to heat, an Ag film having a certain thickness is required, and a film thickness of about several hundred nm or more. Is recommended. Therefore, the lead frame provided with the Ag film has a limit in cost reduction.

  The object of the present invention has been made in view of the above-mentioned problems, can cope with wire bonding of LED chips, can apply a low-cost material instead of silver, and can maintain high reflectivity for a long period of time. An object of the present invention is to provide a lead frame for an LED including a reflective film that has good solderability and can be formed stably and easily, and a method for manufacturing the LED lead frame.

  The present inventors have conceived that aluminum (Al) having a relatively high reflectance among non-noble metals is applied to the reflective film. Al hardly aggregates due to heat, and Cu hardly diffuses by heat, so that deterioration such as discoloration due to heat hardly occurs. In addition, Al forms a natural oxide film (passive film) on the surface, so it has better resistance to sulfidation and halogen than Ag. On the other hand, natural oxide film (aluminum oxide) uses wire bonding and soldering. Inferior to sex. Thus, it has been found that a noble metal film that provides sufficient wire bonding and soldering properties with a thin film that does not hinder the high reflectivity of the Al film is provided on the surface.

  That is, an LED lead frame according to the present invention includes a substrate made of copper or a copper alloy, a reflective film made of aluminum or an aluminum alloy formed on at least one surface of the substrate and having a thickness of 50 nm or more, and the reflective film on the reflective film. And a noble metal film having a thickness of 5 nm or more and 50 nm or less composed of one or more selected from Pd, Au, and Pt.

  In addition, another LED lead frame according to the present invention includes a support member in which a concave portion opened upward for accommodating an LED chip is formed, and a pair of lead members supported by the support member, The pair of lead members is an LED lead frame with a support member that is disposed on the bottom surface of the concave portion with a separation area therebetween and each extends from the concave portion to the outside of the support member. The support member includes a base made of an insulating material, and a reflective film having a thickness of 50 nm or more made of aluminum or an aluminum alloy formed in a region excluding the separation region on the surface of the recess, A substrate made of copper or a copper alloy, a reflective film made of aluminum or an aluminum alloy formed on the substrate inside the concave portion and having a thickness of 50 nm or more, and Pd, Au, Pt formed on the reflective film And a noble metal film having a film thickness of 5 nm or more and 50 nm or less selected from one or more selected from the above.

  Such a lead frame for LED has a high reflectivity because the reflective film is formed of aluminum, and has sufficient heat resistance, sulfidation resistance, and halogen resistance, and a predetermined noble metal on the surface. By providing the thin film made of, sufficient wire bonding property and solderability are imparted. Further, the lead frame for LED has a noble metal film directly formed on the reflective film made of aluminum without forming an oxide film, thereby improving the adhesion between the reflective film and the noble metal film. Is preferable because it does not peel off.

  In each of the LED lead frames according to the present invention, an Ni plating film having a thickness of 0.5 μm or more or an Ag plating film having a thickness of 0.1 μm or more may be further formed between the substrate and the reflective film. .

  Such an LED lead frame has a smooth surface such as a Ni film or an Ag film formed by plating on the substrate, and the surface of the reflective film and the noble metal film becomes smooth. The rate is improved.

  The reflective film and the noble metal film provided on the LED lead frame according to the present invention can be formed by physical vapor deposition using an evaporation source made of each film material. That is, the LED lead frame manufacturing method according to the present invention includes an aluminum film forming step of forming a reflective film on a substrate made of copper or a copper alloy by a physical vapor deposition method using an evaporation source made of aluminum or an aluminum alloy. And a noble metal film forming step of forming a noble metal film using an evaporation source composed of one or more selected from Pd, Au, and Pt by physical vapor deposition. In the aluminum film forming step and the noble metal film forming step, the reflection film and the noble metal film can be formed in succession using the two evaporation sources in order. Alternatively, after the aluminum film forming step, the noble metal film can be formed after removing the natural oxide film formed on the reflective film surface in the noble metal film forming step.

  In the LED lead frame manufacturing method according to such a procedure, the reflective film and the noble metal film are provided with stable components and film thicknesses, and the noble metal film can be formed without a natural oxide film on the reflective film surface. An LED lead frame having good adhesion between the reflective film and the noble metal film can be easily manufactured. In the manufacturing method, the film may be continuously formed efficiently using a film forming apparatus capable of providing both the reflection film and the noble metal film, or the natural oxide film may be formed before the noble metal film is formed. It is also possible to manufacture using a film forming apparatus provided with only one evaporation source of the reflective film or the noble metal film.

  Further, the manufacturing method of the LED lead frame according to the present invention for manufacturing the LED lead frame with the supporting member is the insulating material before the reflective film is formed in the manufacturing method of the LED lead frame. Then, a substrate forming step for forming a substrate of a support member having a shape having a recess opened upward may be further performed. In the base body forming step, the base body is integrally formed so that the substrate is disposed as a pair of lead members on the bottom surface of the concave portion with a separation area therebetween. The reflective film is formed in a region excluding the separation region on the surface of the concave portion simultaneously with the substrate.

  In the LED lead frame manufacturing method according to such a procedure, a reflective film can be simultaneously formed on both the substrate and the surface of the support member (on the substrate).

  In the LED lead frame manufacturing method according to the present invention, a plating step of forming a Ni plating film or an Ag plating film on the substrate by plating may be further performed before the aluminum film forming step.

  In the LED lead frame manufacturing method according to such a procedure, since a Ni plating film or an Ag plating film having a smooth surface is formed on the base of the reflection film, it is possible to manufacture an LED lead frame having a high regular reflectance. it can.

  The LED lead frame according to the present invention can be connected by wire bonding by mounting an LED chip, and the emitted light is used with high efficiency to improve the brightness of illumination light, and the elapsed time of use. It is possible to suppress the deterioration such as attenuation of illumination light due to the light, and to be mounted by soldering on a wiring board or the like, and to obtain an inexpensive light emitting device. In addition, according to the LED lead frame manufacturing method of the present invention, the LED lead frame can be easily manufactured.

(A), (b) is sectional drawing which shows the structure of the lead frame for LED which concerns on 1st Embodiment of this invention. It is an external view which shows the structure of the surface mount type light-emitting device which uses a LED chip as a light source, (a) is a perspective view, (b) is a top view. It is sectional drawing which shows the structure of the light-emitting device using the LED lead frame which concerns on 1st Embodiment of this invention, and is a figure corresponding to the AA arrow sectional drawing of FIG. It is a schematic diagram of the lead frame for LED which concerns on the modification of 1st Embodiment of this invention, (a) is a top view of a board | substrate, (b) is a top view which provided the supporting member in the lead frame for LED (a The figure corresponding to the partial enlarged view of (), (c) is a BB arrow directional cross-sectional view of (b). It is an external view which shows the structure of the lead frame for LED which concerns on 2nd Embodiment of this invention, (a) is a top view, (b) is CC sectional view taken on the line of (a), (c) is It is the figure before the formation of a reflecting film, and is a figure corresponding to DD sectional view taken on the line of (a). It is sectional drawing which shows the structure of the lead frame for LED which concerns on the modification of 2nd Embodiment of this invention, and is a figure corresponding to the BB arrow sectional drawing of FIG.4 (b). It is a schematic diagram explaining the evaluation method of the solderability in an Example.

  The LED lead frame according to the present invention is a component for constituting a light emitting device in which an LED chip is mounted as a light source and connected by wire bonding, and the shape and form of the light emitting device, as well as the LED chip mounting form and product. According to the form etc. provided to the user, it is configured in a required shape and form. Hereinafter, the LED lead frame of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
An LED lead frame (hereinafter referred to as a lead frame) according to a first embodiment of the present invention will be described with reference mainly to FIG. The lead frame 1 according to the present invention is a wiring for supplying a driving current for causing a LED chip (see FIGS. 2 and 3), which is a light source of a light emitting device, to emit light, and reflects light emitted from the LED chip. It is a reflecting plate. As shown in FIGS. 2 and 3, the lead frame 1 is assembled and used as a pair of positive and negative lead members 1a and 1c of a light emitting device.

  A lead frame 1 according to the first embodiment shown in FIG. 1A includes a substrate 11, a reflective film 13 formed on at least one surface of the substrate 11, and a noble metal film 14 formed thereon, Is provided. The reflective film 13 and the noble metal film 14 may be formed only on the upper surface (hereinafter referred to as the “front surface” as appropriate) of the substrate 11 on which the LED chip is mounted, or the lower surface (back surface) of the substrate 11 is included. Further, it may be formed on both surfaces, or may be formed only on a part of the surface of the substrate 11, for example, only on a region where light emitted from the LED chip is incident when assembled in the light emitting device. . For example, when used as the lead members 1a and 1c of the light emitting device as shown in FIG. 3, the lead frame 1 is formed in a strip shape and is disposed on the bottom surface of the LED chip mounting portion 22 (inner lead portion). The reflection film 13 and the noble metal film 14 may be formed on the upper surface side of FIG. Further, in the lead frame 1, solder is applied to an external wiring board or the like such as a region (outer lead portion, see FIG. 2B) extending outside the lead members 1 a and 1 c when assembled in the light emitting device. In the region connected at, the reflective film 13 and the noble metal film 14 may be formed, or the substrate 11 may be exposed without being formed, but the reflective film 13 is not exposed on the surface. That is, only the reflective film 13 is not formed. In regions other than these, the lead frame 1 may have the substrate 11 exposed, or may be formed with two layers or only one of the reflective film 13 and the noble metal film 14. Next, elements constituting the lead frame according to the first embodiment will be described in detail.

(substrate)
The substrate 11 is made of copper (Cu) or a Cu alloy and is formed into the shape of the lead frame 1. Examples of Cu alloys include alloys containing Cu as a main component and containing one or more elements such as Ni, Si, Fe, Zn, Sn, Mg, P, Cr, Mn, Zr, Ti, and Sb. A Cu—Fe—P-based copper alloy can be used. The substrate thickness of the substrate 11 is not particularly limited, but is determined according to the shape and form of the light emitting device as well as the shape, and is formed into a base plate (rolled plate) of this required thickness by rolling or the like. Can be manufactured into a required shape by pressing or etching.

  Furthermore, the surface of the substrate 11 is smoothed by etching the surface with an acid such as a mixed solution of strong acid containing nitric acid (chirinic acid) or by crushing the unevenness of the surface of the substrate 11 by coining. It is preferable that As described above, the substrate 11 is manufactured by forming a rolled plate made of Cu or a Cu alloy. The oxide film formed on the rolled surface or the oxide embedded by rolling after the oxide film is dropped. In order to remove this, a polishing process after rolling is essential. Since the polishing marks remain on the surface by this step, the surface of the substrate 11 becomes rough after the polishing step. Here, if the surface of the lead frame 1 has severe irregularities (there are many high protrusions and deep valleys), the light incident on such a surface is reflected by diffuse reflection, and the regular reflectance decreases. In the lead frame 1, if the regular reflectance of the surface is low and the reflection due to diffuse reflection is large, the light extraction efficiency is lowered when the light emitting device is used. As for the surface properties of the reflective film 13, the surface shape of the base is easily maintained, and the noble metal film 14 on the outermost surface is extremely thin, so that the surface roughness of the substrate 11 substantially matches the surface roughness of the lead frame 1. Therefore, it is preferable to smooth the surface of the substrate 11 as much as possible before the reflective film 13 is formed.

(Reflective film)
In the lead frame 1 according to the present invention, the reflective film 13 has a role of reflecting light emitted from the LED chip when used as a light emitting device, and is formed of aluminum (Al) having a high reflectance. Since Al hardly aggregates due to heat and Cu hardly diffuses by heat, Cu does not diffuse from the substrate 11 and discolor. Furthermore, Al has sufficient sulfur resistance and halogen resistance as a light emitting device by forming a natural oxide film (passive film) on the surface in an oxidizing atmosphere such as air. The component of the reflective film 13 is not limited to Al alone, but may be formed of industrially pure Al (1000 series Al), or an Al alloy as long as the high reflectance of Al is maintained. For example, an Al—Gd alloy provides a reflective film with high alkali resistance. Such a reflective film 13 can be formed by physical vapor deposition using an evaporation source formed of a component of the reflective film 13, that is, Al or an Al alloy (described in detail in a manufacturing method described later). ).

  The reflection film 13 has a film thickness of 50 nm or more in order to reflect the light emitted from the LED chip without transmitting when the light-emitting device is used. On the other hand, even if the reflective film 13 is provided thicker than 500 nm, the effect of further improving the reflectance is saturated, and the film formation time becomes longer, which is not preferable for production. The following is preferable.

  Here, since the reflective film 13 is formed of Al or an Al alloy, when exposed to the atmosphere or the like as described above, a natural oxide film having a film thickness of about 10 nm and at least about 5 nm is formed on the surface. Since aluminum oxide has low crimpability and solderability with wire in wire bonding, in the lead frame having the reflective film 13 provided on the outermost surface, connection failure between the LED chip and an external wiring board or the like May occur. Furthermore, unlike an oxide film of Cu or the like, an aluminum oxide film is difficult to be removed by a flux added to a general solder. Note that high solderability means melting at the part in contact with the solder droplet and alloying with the solder and high wettability of the solder droplet. Aluminum oxide is alloyed with the solder. No wettability. Therefore, the lead frame 1 is provided with the noble metal film 14 excellent in the press-bonding property and the soldering property with respect to the wire on the reflective film 13, that is, the outermost surface, thereby providing the wire bonding property and the soldering property. In addition, the reflective film 13 has low adhesion to the noble metal film 14 in the state where the oxide film is formed on the surface, and there is a possibility that the noble metal film 14 is peeled off and detached together with the crimped wire. Furthermore, since the noble metal film 14 is thin, when the surface melts in contact with the solder droplets in the lead frame soldering, the underlying oxide film is exposed, and the noble metal film 14 is not provided. Similarly, solder wettability decreases. Therefore, the oxide film at the interface between the reflective film 13 and the noble metal film 14 (the oxide film on the surface of the reflective film 13 before the noble metal film 14 is formed) is less than 5 nm. Although details will be described later in the manufacturing method, before the noble metal film 14 is formed, the oxide film is not formed (removed) on the surface of the reflective film 13.

(Precious metal film)
The noble metal film 14 is provided on the outermost surface of the lead frame 1 on the reflective film 13 and is formed of a metal or alloy made of one or more selected from palladium (Pd), gold (Au), and platinum (Pt). The The noble metal film 14 provides wire bondability when the lead frame 1 is mounted on a light emitting device with an LED chip mounted thereon, and solderability when the assembled light emitting device is mounted on a wiring board or the like. That is, Pd, Au, and Pt have good crimpability of a wire made of Au or the like, or have sufficient solderability (easiness of alloying with solder, wettability of solder), and even a very thin film is sufficient. Wire bondability and solderability can be obtained. In addition, Pd, Au, and Pt are excellent in corrosion resistance despite the fact that no passive film is formed on the surface thereof, so that the conductivity as the wiring of the lead frame 1 is not lowered and the reflectance is compared. Therefore, the reflectivity of the lead frame 1 is not greatly lowered from the high reflectivity of Al of the reflective film 13.

  The noble metal film 14 has a film thickness of 5 nm or more in order to impart sufficient wire bonding property and solderability to the lead frame 1. On the other hand, since the reflectance of the noble metal film 14 is lower than that of Al (reflection film 13), if the film thickness is too thick, the reflectance of the lead frame 1 is lowered. Moreover, since the cost of the material of the noble metal film 14 is high, the thickness of the lead frame 1 is increased when the thickness is increased. Therefore, the noble metal film 14 has a thickness of 50 nm or less. Thus, since the noble metal film 14 is relatively thin and uniformly formed, the components of the noble metal film 14, that is, Pd, It is preferable to form a film using an evaporation source formed of at least one selected from Au and Pt (described in detail in the manufacturing method described later). In addition, when Pd, Au, and Pt are formed into such a thin film by a sputtering method, the noble metal film 14 tends to be a film having a pinhole, but there is no influence on wire bonding property and solderability, Further, even if a passive film is formed in the gap on the surface (interface) of the reflective film 13 through the pinhole, the adhesion of the noble metal film 14 does not deteriorate.

  As another embodiment of the present invention, a Ni plating film or an Ag plating film may be further formed under the reflective film. That is, the lead frame 1B according to the modification of the first embodiment shown in FIG. 1B includes a substrate 11 and a base plating film (Ni plating film, Ag plating film) formed on at least one surface of the substrate 11. 12, a reflective film 13 formed thereon, and a noble metal film 14 formed thereon. Similarly to the reflective film 13 and the noble metal film 14, the base plating film 12 may be formed only at least in a region where light emitted from the LED chip is incident when assembled in the light emitting device. It may be formed entirely. Further, since the Ni film and the Ag film have good solderability, that is, the base plating film 12 has good solderability, when formed on the outer lead portion, the reflective film 13 and the noble metal film 14 are formed thereon. You may expose without forming. Therefore, in the lead frame 1B, as shown in FIG. 4C, for example, the base plating film 12 is formed on the entire surface (front surface, back surface, end surface) of the substrate 11, and the reflective film 13 and the noble metal film are formed only on the top surface (front surface). 14 (represented by one layer as 13/14 in the figure) may be formed. The substrate 11, the reflective film 13 and the noble metal film 14 are the same as the lead frame 1 shown in FIG. Hereinafter, the base plating film 12 will be described.

(Under plating film)
In the lead frame 1 </ b> B, the base plating film 12 is formed on the surface of the substrate 11 and is provided as the base of the reflective film 13. As described above, the reflective film 13 formed by physical vapor deposition is easy to maintain the surface property of the base, that is, when the reflective film 13 is provided directly on the substrate 11, the surface shape of the substrate 11 is maintained and remains as it is. The surface properties of the lead frame 1 are obtained. Therefore, in this modification, a plating film that fills the unevenness of the surface of the substrate 11 and forms a smooth surface can be easily formed on the surface of the substrate 11 made of Cu or Cu alloy and has a relatively high reflectance. It is made of metal and used as the base of the reflective film 13. As such a metal, nickel (Ni), Ag, Cu, chromium (Cr), and tin (Sn) can be applied, and Ni and Ag are particularly preferable. Although affected by the surface roughness of the substrate 11, the film thickness is 0.5 μm or more in the case of the Ni plating film and in the case of the Ag plating film in order to sufficiently smooth the surface of the base plating film 12. The thickness is preferably 0.1 μm or more. Although the upper limit of the film thickness of the base plating film 12 is not specified, the effect of smoothing the surface is saturated even if the film thickness is excessively thick, and if it is formed unnecessarily thick, the productivity is lowered, and further Ag plating is performed. Since the cost of the film increases, the thickness is preferably 8 μm or less in both cases of the Ni plating film and the Ag plating film.

  As long as the Ni plating film is a plating film that forms a smooth surface, the component is not limited to Ni alone, and is formed of, for example, a Ni alloy such as a Ni—Co alloy, a Ni—P alloy, or a Ni—Fe alloy. It may be a plating film, and can be formed by a known plating method such as electroplating. Further, a bright Ni plating film is preferable because a smoother surface can be formed with respect to the surface roughness of the substrate 11.

  As long as the Ag plating film is a plating film that forms a smooth surface, the component is not limited to Ag alone (pure Ag). For example, an alloy with a noble metal such as an Ag—Au alloy or an Ag—Pd alloy, or A plating film formed of an Ag alloy such as an Ag—Bi alloy may be used. In addition, the Ag plating film may be any one of matte Ag plating, semi-gloss Ag plating, and glossy Ag plating formed by a known plating method, but light emitted from the LED chip when used as a light emitting device. In order to emit light to the outside with high efficiency, glossy Ag plating is most preferable.

  Even when the base plating film 12 is formed of Cu, Cr, or Sn, it may be a plating film formed by a known plating method as long as the plating film forms a smooth surface. In general, bright copper plating, bright chrome plating, bright tin plating with reflow treatment, and the like.

  Thus, by providing the base plating film 12 as the base of the reflective film 13, the lead frame 1B having excellent light extraction efficiency when assembled in the light emitting device can be easily obtained.

  The plan view shape of the lead frames 1 and 1B (hereinafter collectively referred to as the lead frame 1 as appropriate) is not particularly limited, and is designed according to the shape and form of the light emitting device. For example, the substrate 11A (see FIG. 4 (a)), a plurality of lead frames 1 may be connected. Further, the lead frame 1 may be a coiled strip or the like. In this case, the lead frame 1 is processed by cutting, molding, or the like according to the shape or the like of the light emitting device when the light emitting device is manufactured.

(Lead frame manufacturing method)
The lead frame according to the first embodiment of the present invention is not particularly limited as long as it is a method capable of forming the above configuration, and may be manufactured by any method. For example, in the lead frame 1 shown in FIG. 1A, a substrate manufacturing step S1 for manufacturing a substrate 11, an aluminum film forming step S5 for forming a reflective film 13 on the substrate 11, and a noble metal film 14 on the surface of the reflective film 13 are provided. It can manufacture by the method of performing the noble metal film-forming process S6 to form (illustration omitted). In addition, a code | symbol is attached | subjected for description to each process. Below, an example of the manufacturing method of the lead frame 1 is demonstrated.

  In the substrate manufacturing step S1, a Cu or Cu alloy as a material is continuously cast to produce a cast plate (for example, a thin plate ingot), and then annealing, cold rolling, intermediate annealing and aging treatment, and finish rolling, A base plate having a required thickness is manufactured through a process such as polishing. The base plate 11 can be obtained by forming this base plate into the shape of the lead frame 1 by cutting or pressing.

  The reflective film 13 and the noble metal film 14 are formed by physical vapor deposition such as sputtering, respectively, in accordance with the composition of the reflective film 13 and the noble metal film 14, that is, Al (or Al alloy) and noble metal, respectively. A film can be formed using an evaporation source (target). For example, the aluminum film forming step S5 and the noble metal film forming step S6 can be performed continuously by using a sputtering apparatus that includes a plurality of electrodes on which a target is provided and can switch the electrode to which a voltage is applied.

In order to improve the adhesion between the reflective film 13 and the substrate 11, in the aluminum film forming step S5, the surface is irradiated with an Ar ion beam or a high frequency is applied in an Ar atmosphere before the film formation. 11 It is preferable to remove dirt present on the surface. First, an Al (or Al alloy) target and a noble metal target are placed on separate electrodes, and the substrate 11 is placed in a chamber of a sputtering apparatus. Next, after evacuating the chamber to a pressure of 1.3 × 10 ⁻³ Pa or less, Ar gas is introduced into the chamber, and the pressure in the chamber is set to a predetermined pressure, for example, about 2 × 10 ⁻² Pa. adjust. Then, a predetermined discharge voltage is applied to the ion gun to generate Ar ions, and a predetermined acceleration voltage and beam voltage are further applied to irradiate the surface of the substrate 11 with the Ar ion beam. Thereafter, while introducing Ar gas into the chamber, the pressure in the chamber is adjusted to about 0.27 Pa, and sputtering is performed by applying a DC voltage (output 100 W) to the Al target to form the reflective film 13. To do. When the formation of the reflective film 13 is completed, the voltage application to the Al target is stopped to complete the step S5. Subsequently, as a noble metal film forming step S6, a DC voltage (output 100 W) is applied to the noble metal target for sputtering. The lead frame 1 can be manufactured by forming the noble metal film 14. The reflective film 13 and the noble metal film 14 can be formed in desired film thicknesses by controlling the voltage application time to each target.

  As described above, when the reflective film 13 and the noble metal film 14 are continuously formed in the same sputtering apparatus in a low oxygen atmosphere with Ar or the like, the surface of the reflective film 13 is not exposed to the atmosphere. The noble metal film 14 is formed on the reflective film 13 with good adhesion without forming a natural oxide film. On the other hand, when the reflective film 13 and the noble metal film 14 are formed by different film forming apparatuses, or after the reflective film 13 is formed, the chamber is opened and the evaporation source is exchanged. In the noble metal film forming step S6, the natural oxide film formed on the surface of the reflective film 13 is removed before the noble metal film 14 is formed. Specifically, the natural oxide film formed on the surface of the reflective film 13 can be removed by irradiating the reflective film 13 with an Ar ion beam or applying a high frequency in an Ar atmosphere. That is, the same process as the removal of dirt on the surface of the substrate 11 before the formation of the reflective film 13 in the aluminum film forming step S5 may be performed. A series of operations such as vacuum evacuation in the chamber and pressure adjustment with Ar gas are the same as in the aluminum film forming step S5, and thus description thereof is omitted.

  A lead frame 1B shown in FIG. 1B is a base plating step for forming a base plating film (Ni plating film, Ag plating film) 12 on the substrate 11 before the aluminum film forming step S5 in the manufacture of the lead frame 1. (Plating step) It can be manufactured by a method of further performing S2 (not shown). Steps S1, S5, and S6 have been described in the manufacturing method for manufacturing the lead frame 1, and will be omitted. Hereinafter, the base plating step S2 will be described.

  When a Ni plating film is formed as the base plating film 12, it is preferable to pre-treat the substrate 11 with a degreasing solution, electrolytic degreasing, and an acid solution in advance. For example, after the substrate 11 is immersed in a degreasing solution and degreased, the counter electrode is made of stainless steel 304, and a DC voltage is applied so that the lead frame side is negative, and electrolytic degreasing is performed for about 30 seconds. It can be performed by immersing in a 10% sulfuric acid aqueous solution for about 10 seconds.

Ni plating film, for example, a Watts bath, wood bath, using known plating bath such as sulfamic acid bath, a Ni plate as the counter electrode, the current density 5A / dm ^2, the electroplating conditions such as the plating bath temperature 50 ° C. By performing, it can form into a film. Moreover, it can also be set as a gloss Ni plating film using the plating bath which added the brightener. In this electroplating, a Ni plating film having a desired film thickness can be obtained by adjusting the current density, plating plate speed (plating time), and the like.

Even when an Ag plating film is formed as the base plating film 12, it is preferable to pre-treat the substrate 11 in advance in the same manner as the formation of the Ni plating film. When the Ag plating film is formed of pure Ag, for example, a known plating solution such as a cyan bath or a thiosulfate bath is used, with an Ag (purity 99.99%) plate as a counter electrode, and a current density of 5 A / dm ² , A film can be formed by performing electroplating under conditions such as a plating bath temperature of 15 ° C. Moreover, it can also be set as a gloss Ag plating film using the plating bath which added the brightener. In this electroplating, an Ag plating film having a desired film thickness can be obtained by adjusting the current density, plating plate speed (plating time), and the like, similarly to Ni plating.

  In the case where the base plating film (Ni plating film, Ag plating film) 12 is formed only on one surface (upper surface) of the substrate 11 or only in a part of the region, the substrate 11 is masked with a masking tape or the like other than the lower surface and the region. Thereafter, by performing electroplating in a plating bath, the base plating film 12 can be formed only on a desired portion of the substrate 11.

  In manufacturing the lead frame 1B, in the aluminum film forming step S5 and the noble metal film forming step S6, the substrate 11 on which the base plating film 12 is formed is placed in the chamber of the sputtering apparatus. Further, in the aluminum film forming step S5, in order to improve the adhesion between the reflective film 13 and the base plating film 12, the surface of the base plating film 12 is irradiated with an Ar ion beam before film formation, or a high frequency is generated in an Ar atmosphere. By applying, dirt existing on the surface of the underlying plating film 12 may be removed.

  As described above, the lead frame 1 can be manufactured by performing the steps S1, S5, and S6 in this order. Further, the lead frame 1B can be manufactured by performing the steps S1, S2, S5 and S6 in this order. Further, in the base plating step S2, the base plating film 12 is formed on the entire surface without masking the substrate 11 (11A), and in the aluminum film forming step S5 and the noble metal film forming step S6, the reflective film 13 is formed only on one side (front surface). When the noble metal film 14 is formed, the lead frame 1B shown in FIG. 4C can be manufactured. Further, before forming the substrate 11 in the substrate manufacturing step S1, the base plating step S2, or further the aluminum film forming step S5 and the noble metal film forming step S6, are processed into the shape of the lead frame 1 (1B). It can also be manufactured.

[Second Embodiment]
Next, an LED lead frame according to a second embodiment will be described with reference to FIG. The same elements as those of the LED lead frame according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The LED lead frame according to the second embodiment is a component for constituting a surface-mounted light-emitting device (see FIG. 2) mounted with an LED chip as a light source.

  As shown in FIGS. 5A and 5B, a lead frame with a support member (LED lead frame) 10B according to the second embodiment is formed with a concave LED chip mounting portion (concave portion) 22 opened upward. And a pair of positive / negative lead members 1a and 1c supported by the support member 2B. The lead members 1a and 1c are arranged on the bottom surface of the LED chip mounting portion 22 so as to be separated from each other, and each extends from the LED chip mounting portion 22 to the outside of the support member 2B, that is, inside the support member 2B ( The LED chip mounting portion 22) penetrates outward. When the lead frame with support member 10B is assembled to the light emitting device, the support member 2B is a container and a base for accommodating the LED chip as the light source in the LED chip mounting portion 22, and the lead members 1a and 1c are the LEDs. Wiring for supplying drive current to the chip. The LED lead frame according to the second embodiment uses the LED lead frame 1 according to the first embodiment as a pair of lead members, and this is a support member formed with a recess for accommodating the LED chip. In the following, it is referred to as a lead frame with a support member. Next, elements constituting the lead frame with a support member according to the second embodiment will be described in detail.

(Lead material)
As shown in FIG. 5 (a), the lead members 1a and 1c are belt-shaped and are juxtaposed along the longitudinal direction, and spaced apart at the right side of the center in the longitudinal direction on the bottom surface of the LED chip mounting portion 22. They are opposed to each other, and each penetrates to the outside (both left and right sides in FIG. 5) of the support member 2B. Therefore, in the LED chip mounting part 22, the left lead member 1a is longer than the right lead member 1c and is arranged to the center of the bottom surface. The area | region arrange | positioned on the bottom face of the LED chip mounting part 22 of the lead members 1a and 1c is called an inner lead part, and the area | region extended outside the support member 2B is called an outer lead part (refer FIG.2 (b)). Thus, one of the lead members (lead member 1a) is disposed at the center of the bottom surface of the LED chip mounting portion 22, so that the LED chip mounted on the lead frame with support member 10B is stably mounted. The lead member 1a can suitably reflect the light irradiated downward from the LED chip. Specifically, the LED chip is placed at the approximate center of the inner lead portion of the lead member 1a on the bottom surface of the LED chip mounting portion 22 (the region indicated by the thick dashed frame in FIG. 5A). Further, regions on both sides (left and right in the drawing) of the LED chip in the inner lead portions of the lead members 1a and 1c are regions for wire bonding. That is, the inner lead portion is a region for electrically connecting the mounted LED chip, and at the same time, constitutes a reflector that reflects the light emitted by the LED chip. The outer lead portion is a region for electrical connection to an external power source or wiring, that is, a region for soldering.

  The lead members 1a and 1c are composed of the lead frame 1 (see FIG. 1A) according to the first embodiment, that is, the substrate 11, the reflective film 13 formed on at least one surface of the substrate 11, and the And a noble metal film 14 formed thereon. As shown in FIG. 5B, the lead members 1a and 1c are arranged on the bottom surface of the LED chip mounting portion 22 of the support member 2B with the surface including the reflective film 13 and the noble metal film 14 facing upward. 5B, the lead members 1a and 1c are composed of the lead frame 1. Unlike the first embodiment shown in FIG. 3, the reflective film 13 and the noble metal film 14 are provided only on the inner lead portion. The area embedded in the outer lead portion and the support member 2 </ b> B includes only the substrate 11. Such a structure will be described later in the manufacturing method. Further, the lead members 1a and 1c are formed of a base plating film (Ni plating film, Ag plating film) 12 between the substrate 11 and the reflective film 13 as in the lead frame with support member 10C according to the modification shown in FIG. (Refer FIG. 6 shows the reflection film 13 as one layer as 13/14 together with the noble metal film 14). Since the elements such as the substrate 11 constituting the lead members 1a and 1c are the same as those of the lead frames 1 and 1B according to the first embodiment, the description thereof is omitted.

(Support member)
The support member 2B, like the support member 2 of the light emitting device shown in FIG. 2, includes a cup-shaped resin molded body (base) 21 in which a concave LED chip mounting portion (recess) 22 is formed, and further includes an LED chip mounting. A reflective film 23 formed on the surface of the portion 22 is provided. The LED chip mounting part 22 is an open quadrilateral frustum that is rectangular in a plan view and includes a bottom surface and four side surfaces surrounding it. The shape of the LED chip mounting portion 22 is not limited to this, and may be, for example, a square in a plan view, or a truncated cone that opens upward. Further, a region (space) sandwiched between the lead members 1a and 1c in the LED chip mounting portion 22 is referred to as a separation region 28 including a bottom surface and a side surface. The support member 2B is formed into a desired shape according to the shape and form of the light emitting device in which the lead frame with support member 10B is used, the LED chip mounting form, the form provided to the user as a product, and the like.

  The resin molded body 21 is a base of the support member 2B, and is formed by molding a resin that is an insulating material into the shape of the support member 2B. Therefore, the resin molded body 21 is integrated with the lead members 1a and 1c by injection molding (insert molding) or the like so that the lead members 1a and 1c penetrate from the outer side to the inner side (LED chip mounting portion 22). It is preferable to be molded. The resin has only to have heat resistance of 200 ° C. or higher, and engineering plastics such as polyamide (PA) resin, super engineering plastics such as polyphenylene sulfide (PPS) resin, and the like can be used. Moreover, since the surface (bottom surface and side surface) which forms the LED chip mounting part 22 of the resin molding 21 becomes a reflective surface when the reflective film 23 is formed on the surface to form a light emitting device, similarly to the substrate 11 In order to increase the regular reflectance, a smooth surface is preferable.

  The support member 2 </ b> B includes a reflective film 23 on the inner surface thereof, that is, on a region excluding the separation region 28 on the surface (bottom surface and side surface) of the LED chip mounting portion 22. The reflective film 23 is formed of aluminum (Al) or an Al alloy, similarly to the reflective film 13 provided on the lead members 1a and 1c (lead frame 1), and the reflective film 13 and the composition and film of the lead members 1a and 1c. Although the thickness may be the same or different, the thickness is set to 50 nm or more like the reflective film 13. By forming such a reflective film 23, the reflectance of the surface of the LED chip mounting portion 22 is increased, and the light extraction efficiency is further improved when the light emitting device is formed. In addition, the reflective film 23 formed on each surface (bottom surface and side surface) of the LED chip mounting part 22 may not have the same film thickness. Further, the reflective film 23 does not have to be formed in the area where the lead members 1a and 1c are disposed on the bottom surface of the LED chip mounting portion 22 (under the inner lead portion).

  For these reasons, the reflective film 23 can be formed on the resin molded body 21 that is integrally injection molded with the lead members 1a and 1c. Further, as will be described later, the resin molded body 21 is injection-molded integrally with the lead members 1a and 1c (the base material 11 or the base material 11 on which the base plating film 12 is formed) before the reflection film 13 is formed. The reflective films 13 and 23 can be integrally formed on the surface of the lead part (base material 11 or base plating film 12) and the LED chip mounting part 22 (resin molded body 21). Furthermore, by forming the LED chip mounting portion 22 in an open shape that opens upward, the reflective films 13 and 23 are formed by physical vapor deposition from the opening (upper) of the LED chip mounting portion 22 toward the bottom surface. For example, the reflective film 23 is simultaneously formed on the inclined side surfaces as well as the inner lead portions and the bottom surfaces of the lead members 1a and 1c on the bottom surfaces.

  Further, similarly to the reflective films 13 and 23, the noble metal film 14 is applied to the lead members 1a and 1c supported on the resin molded body 21 (support member 2B) and disposed on the bottom surface of the LED chip mounting portion 22 by physical vapor deposition. When the film is formed, a noble metal film having the same composition is also formed on each surface of the LED chip mounting portion 22 (omitted in FIGS. 5B and 6). Similar to the noble metal film 14 in the lead members 1a and 1c, such a noble metal film may be formed because the high reflectivity of the reflective film 23 is not inhibited as long as the film thickness is 50 nm or less. Note that when the lead frame with support member 10B is assembled to the light emitting device, no wire bonding is performed on the surface of the LED chip mounting portion 22 of the support member 2B, so that the noble metal film like the lead members 1a and 1c (lead frame 1) is used. Need not be provided on the reflective film 23, and the reflective film 23 may be exposed. Further, in FIG. 5B, a reflective film is integrally shown on the surface of the LED chip mounting portion 22 including the surfaces of the lead members 1a and 1c. However, what is formed on the resin molded body 21 is a reflective film. 23, what is formed on the substrate 11, that is, on the surfaces of the lead members 1a and 1c, is the reflective film 13.

  Here, when a reflection film made of Al or an Al alloy or further a noble metal film is formed on the entire surface (bottom surface and side surface) of the LED chip mounting portion 22, the lead member 1a, 1c is short-circuited. Therefore, the reflective film 23 and the noble metal film are not formed in the region in the separation region 28 on the bottom surface and the side surface (side surface along the longitudinal direction) of the LED chip mounting portion 22. Further, the reflection film 23 and the like may be formed on the surface other than the surface of the LED chip mounting portion 22, that is, on the upper surface (upper end surface of the side wall) or the outer side surface of the support member 2B. The lead members 1a and 1c are not formed continuously from the inner lead portions. That is, the reflective film 23 separates the separation region 28 between a region on the bottom surface of the LED chip mounting portion 22 that is continuous with the region where the lead member 1a is disposed and a region that is continuous with the region where the lead member 1c is disposed. And completely separated. A method for forming such a reflective film 23 will be described in detail in a manufacturing method described later.

(Manufacturing method of lead frame with support member)
The lead frame with support member 10B according to the second embodiment is not particularly limited as long as it can form the above-described configuration, and may be manufactured by any method. For example, the lead frame with support member 10B shown in FIGS. 5A and 5B includes a substrate manufacturing step S1, an aluminum film forming step S5, and a noble metal film forming step S6 in the method for manufacturing the lead frame 1 according to the first embodiment. Furthermore, it can manufacture by the method of performing resin molding process S3 and mask process S4 (illustration omitted). Below, an example of the manufacturing method of the lead frame with a supporting member which concerns on 2nd Embodiment is demonstrated.

  Since the substrate manufacturing step S1 is the same as that of the first embodiment, description thereof is omitted. In this step, the substrate 11 molded into the shape of the lead members 1a and 1c is obtained.

  In the resin molding step S3, the resin molded body 21 is molded integrally with the lead members 1a and 1c by injection molding (insert molding) or the like. Specifically, the resin is molded integrally with the substrate 11 so that the substrate 11 penetrates from the outside of the resin molded body 21 to the inside (LED chip mounting portion 22). In addition, although it is preferable that the surface used as the bottom face of the LED chip mounting part 22 of the resin molding 21 is the same as the upper surface (upper surface of the board | substrate 11) of the lead members 1a and 1c, for example, it is flush with the lower surface of the board | substrate 11. May be formed.

  Next, the reflective film 13 is formed on the surface of the substrate 11 in the inner lead portions of the lead members 1a and 1c, and the reflective film 23 is formed on the surface of the LED chip mounting portion 22 of the resin molded body 21 (aluminum film forming step S5). . However, if the reflective films 13 and 23 are formed directly from the opening of the LED chip mounting portion 22 toward the bottom surface, that is, in the entire area of the surface of the LED chip mounting portion 22, as described above, the surface of the LED chip mounting portion 22 is formed. The lead members 1a and 1c are short-circuited via the reflective film (aluminum film). Therefore, in order to prevent this short circuit, a mask process S4 is performed before the aluminum film forming process S5. Hereinafter, the mask process S4 will be described.

  The mask process S4 is a preparation process for the aluminum film forming process S5 and the noble metal film forming process S6. By masking the separation region 28 of the LED chip mounting portion 22, the reflective film is applied to the separation region 28 in the subsequent steps S5 and S6. 13 and 23 and the noble metal film 14 are not formed. The mask method is not particularly defined, and a known method can be applied. As an example, as shown in FIG. 5C, the same as the cross-sectional shape taken along the line CC of the LED chip mounting portion 22 (internal space). A plate-like mask having an inverted trapezoidal shape with an ear portion projecting to the side of the resin molded body 21 and having the same thickness as the distance between the lead members 1a and 1c on the bottom surface of the LED chip mounting portion 22 ( Mask plate). Then, this mask plate is fitted to the LED chip mounting portion 22 of the resin molded body 21 in accordance with the position of the separation region 28 from the opening portion toward the bottom surface. The structure of the mask plate is not particularly limited, and for example, a metal material such as copper, aluminum, titanium, SUS, or the like produced by etching or pressing can be used. With this mask plate fitted to the LED chip mounting portion 22, an aluminum film forming step S5 and a noble metal film forming step S6 are performed. At this time, a mask (not shown) is also provided to cover the outer lead portion of the lead members 1a and 1c other than the surface (outer surface) of the LED chip mounting portion 22 in the support member 2B (resin molded body 21). Also good.

  The aluminum film forming step S5 and the noble metal film forming step S6 are the same as the steps S5 and S6 in the first embodiment, respectively, and the reflective films 13 and 23 and the noble metal film 14 having a predetermined composition and film thickness are formed on the lead member 1a. , 1c and the LED chip mounting portion 22 including the inner lead portion. As in the first embodiment, the steps S5 and S6 may be performed continuously, or after the aluminum film forming step S5, the surface of the reflective films 13 and 23 is exposed to the atmosphere and the noble metal film is formed. The noble metal film 14 may be formed after removing the natural oxide film in step S6.

  Here, the resin molded body 21 that has penetrated the substrate 11 is placed in the chamber of the sputtering apparatus so that the bottom surface of the LED chip mounting portion 22 and the top surfaces of the lead members 1a and 1c face the Al target and the noble metal target. It is preferable. By being placed in this way, depending on the inclination angle of the side surface of the LED chip mounting portion 22, film formation on this side surface is formed more than film formation on the bottom surface and the top surfaces of the lead members 1a and 1c. The film speed becomes slow. Therefore, in the aluminum film forming step S5, the reflective film 23 formed on the side surface of the LED chip mounting portion 22 of the resin molded body 21 may be formed in accordance with the required film thickness. On the other hand, in the noble metal film forming step S6, since the noble metal film is necessary only on the surfaces of the lead members 1a and 1c, the noble metal film may be formed according to the film thickness of the noble metal film 14 on the surface. Even if it is formed on the reflective film 23, there is no problem as long as it is equal to or less than the thickness of the noble metal film 14 in the lead members 1a and 1c.

  After the reflective films 13 and 23 and the noble metal film 14 are formed, when the mask plate is removed from the LED chip mounting portion 22, as shown in FIGS. 5 (a) and 5 (b), on the surface of the LED chip mounting portion 22, A region where the reflection film 23 and the like are not formed over the bottom surface and the side surface and the resin molded body 21 is exposed becomes the support member 2B existing in a band shape along the separation region 28, and the lead frame 10B with the support member is manufactured. Thus, by preventing the metal film such as the reflective film 23 from being formed in the separation region 28, it is possible to prevent short-circuit between the lead members 1 a and 1 c via the reflective film 23 or the like and to ensure insulation. Can do. Further, since the space between the inner lead portions (the separation region 28) of the lead members 1a and 1c is filled with the resin constituting the resin molded body 21 or the sealing resin when assembled in the light emitting device, the lead member The insulation between 1a and 1c is maintained. Note that the thickness of the mask plate does not have to coincide with the distance between the lead members 1a and 1c (the width of the separation region 28), and if the short circuit between the lead members 1a and 1c can be prevented, the region where the reflective film 23 is not formed. Is not limited to this, and may be wider or narrower than the separation region 28.

  As described above, the support member-equipped lead frame 10B according to the second embodiment can be manufactured by performing the steps S1, S3, S4, S5, and S6 in this order.

  When the lead frame 1B (see FIG. 1B) is applied to the lead members 1a and 1c as in the lead frame with support member 10C shown in FIG. 6, the substrate 11 is plated on the base as in the first embodiment. A base plating step (plating step) S2 for forming the film 12 is further performed. That is, it is manufactured by a method of performing the same steps S1, S3, S4, S5 and S6 as the manufacturing method of the lead frame with support member 10B, and further performing a base plating step (plating step) S2 before the aluminum film forming step S5. be able to. Since the base plating step S2 is the same as the step S2 in the first embodiment, description thereof is omitted. Similar to the manufacturing method of the lead frame 1B according to the first embodiment, the base plating step S2 may be performed before forming in the substrate manufacturing step S1, and then processed into the shape of the lead members 1a and 1c. In the lead frame with support member 10C, the lower surface of the substrate 11 (11A) is masked in the base plating step S2 to form the base plating film 12 only on the upper surface, as shown in FIG. As in the lead members 1a and 1c (lead frame 1B) of the lead frame with support member 10A, the base plating film 12 may be formed on both surfaces and end surfaces of the substrate 11A. The support member 2C may be formed by performing the resin molding step S3 on the substrate 11A on which the base plating film 12 thus obtained is formed. Thereafter, the steps S4, S5, and S6 are performed in this order to support the substrate 11A. The lead frame with member 10C is manufactured.

  As described above, the lead frame with support member 10C according to the modified example of the second embodiment can be manufactured by performing the steps S1, S2, S3, S4, S5, and S6 in this order. However, in this modification, it can be manufactured by changing the order in which the base plating step S2 is performed in accordance with the portion where the base plating film 12 of the lead members 1a and 1c is formed. For example, the substrate 11 is manufactured and formed into the shape of the lead members 1a and 1c (step S1), and the resin molded body 21 is formed integrally with the substrate 11 before forming the base plating film 12 (step S3). . Next, the base plating film 12 is formed by electroplating on the substrate 11 penetrating the resin molded body 21 (step S2). According to electroplating, no plating film is formed on the surface of the resin molded body 21 made of an insulating material. In the same manner as described above, a mask plate is fitted to the LED chip mounting portion 22 of the resin molded body 21 (step S4), and then the reflective films 13 and 23 and the noble metal are formed on the surface of the base plating film 12 and the resin molded body 21. The film 14 is formed (steps S5 and S6). In the lead frame with a support member manufactured by changing the order of the step S2 and the step S3, the region (between the inner lead portion and the outer lead portion) embedded in the support member 2C of the lead members 1a and 1c is a substrate. 11, the base plating film 12 is not formed on the lower surface (back surface) of the inner lead portion without providing a mask on the lower surface of the substrate 11 in the base plating step S2.

  Since the lead frame with support member 10C uses only the mask plate shown in FIG. 5C in the mask process S4, the reflective film 23, the upper surface of the support member 2C and the outer lead portions of the lead members 1a and 1c are also formed. 13 and the noble metal film 14 are formed, but the reflection film 23 and the like are not formed on the extension of the separation region 28 on the outer surface of the support member 2C by the ears of the mask plate, and the short circuit between the lead members 1a and 1c. Does not occur.

[Light emitting device]
Next, an example of the light emitting device using the LED lead frame (lead frame and lead frame with a supporting member) according to the first and second embodiments of the present invention will be described.
An example of a method of assembling a light emitting device using the lead frames with supporting members 10B and 10C according to the second embodiment and the modifications thereof is as follows. First, an adhesive made of a silicone die bonding material or the like is applied to the approximate center of the LED chip mounting portion 22 on the surface of the inner lead portion of the lead member 1a (the LED chip mounting region shown in FIG. Adhere and fix the LED chip. Next, the electrodes of the LED chip are connected to the inner lead portions of the lead members 1a and 1c with gold wires by wire bonding. And it seals by filling sealing resin, such as an epoxy resin, into the LED chip mounting part 22, and becomes a surface mount type light-emitting device (refer FIG. 2) which mounted the LED chip as a light source. In addition, in LED lead frame 10C, after being manufactured in a light emitting device in a state of being connected by a substrate 11A, the LED lead frame 10C is used after being separated by a thick broken line shown in FIG. In addition, a light-emitting device on which LED chips each having a pair of electrodes provided on both upper and lower surfaces can be assembled. In the case of an LED chip having an n-electrode on the lower surface, the negative lead electrode 1c is a lead frame with a support member disposed up to the approximate center of the LED chip mounting portion 22, and the LED chip is made of a conductive adhesive. The n electrode is mounted while being electrically connected to the lead electrode 1c, and the p electrode on the upper surface is connected to the lead member 1a by wire bonding.

  The lead frame 1, 1 </ b> B according to the first embodiment and its modified example is also resin molded body 21 (support member 2) in the same manner as in the second embodiment so that the one molded in a predetermined plan view shape penetrates. , 2A), the lead frame with support member 10, 10A can be manufactured and used as a component of a surface mount type light emitting device. Accordingly, the resin may be injection-molded integrally with the lead frames 1 and 1B as in the resin molding step S3 in the supporting member lead frame manufacturing method according to the second embodiment, that is, in the supporting member lead frame manufacturing method. Steps S1, S2, S5, S6 and S3 are performed in this order. For example, the lead frame 1B is manufactured by applying the substrate 11A in the modification of the first embodiment shown in FIG. 4A, and the support member 2A is integrally formed as shown by a broken line in FIG. 4B. Thus, the lead frame with support member 10A shown in FIG. 4C is obtained. As shown in FIGS. 3 and 4C, the lead frames 10 and 10A with support member thus obtained have a reflective film on the surface of the LED chip mounting portion 22 of the support members 2 and 2A (resin molded body 21). Except that the metal film such as 23 is not formed, the structure is the same as that of the lead frames with support members 10B and 10C (FIGS. 5B and 6) according to the second embodiment. Therefore, it is preferable to increase the reflectance of the surface, such as applying a white resin to the resin molded body 21. Alternatively, for example, a frame surrounding the LED chip may be molded with resin and attached to the lead frame 1 (not shown) without using injection molding. This frame may be attached before or after the LED chip is mounted.

  The lead frames 1 and 1B according to the first embodiment and the modification thereof may be manufactured, for example, in a bullet-type light emitting device (not shown) without forming the support member 2 and the like. In this case, the substrate 11 is formed into a cup shape by press forging a thick portion of a deformed strip (rolled plate having a different thickness in the rolling width direction), and the plate thickness is thin outside the cup shape. The part is made into a shape extending in a strip shape. Then, a base plating film 12, a reflection film 13, and a noble metal film 14 are formed on the cup-shaped inner surface of the substrate 11 to form a lead frame. The cup-shaped inner surface serves as the inner lead portion of the lead member 1a and the LED chip mounting portion 22, and the band-shaped portion serves as the outer lead portion. This is combined with a lead frame 1 (which may be composed of only the substrate 11) made of another member as a lead member 1c to form a set of lead frames. In such a lead frame, the LED chip is mounted on the inner bottom surface of the cup shape and wire bonded, and the cup shape is filled with a sealing resin and sealed. By adopting such a structure, the lead frame 1 can be formed not only under the LED chip but also on the side reflection surface.

  In the light emitting device obtained by using the lead frames 1 and 1B or the support member lead frames 10 to 10C as described above, unlike the Ag film, the reflective film 13 hardly causes aggregation and discoloration due to heat, and is resistant to sulfur and halogen. Since the lead frame 1 and the like do not have a film containing Ag at least near the surface, it is difficult to cause precipitation of Ag nanoparticles and the sealing resin such as epoxy resin is not discolored. The light emitted from the chip can be stably reflected and extracted with high efficiency over a long period of time. Furthermore, such a light-emitting device can be mounted on a wiring board or the like by soldering with a noble metal film 14 provided on the surface of the lead frame 1 or the like, and a wire when the light-emitting device is assembled. Due to good bonding properties, no bonding failure occurs.

  Hereinafter, the present invention will be described in more detail by way of examples of the present invention, but the present invention is not limited to the following examples.

[Sample preparation]
A sample of the lead frame 1 having the laminated structure shown in FIG. 1A is prepared by changing the components and film thicknesses of the reflective film and the noble metal film as described below, and the laminated film shown in FIG. A sample of the lead frame 1B having a structure was produced by changing the components and film thickness of the base plating film.

(Production of substrate)
A Cu-Fe-P copper alloy plate (KLF194H, manufactured by Kobe Steel, Ltd.) having a thickness of 0.1 mm was pressed to produce a substrate (substrate 11A) having the shape shown in FIG. .

(Formation of Ni plating film)
Sample No. About 9-13, 21, Ni plating film was formed as a base plating film on the substrate. As a pretreatment for plating, the substrate was immersed in a degreasing solution, the counter electrode was stainless steel 304, a DC voltage was applied so that the substrate side was negative, and electrolytic degreasing was performed for 30 seconds. Soaked. The surface (entire surface) of the substrate after the pretreatment was subjected to bright Ni plating at a current density of 5 A / dm ² with a watt bath with the following components and a liquid temperature of 50 ° C., with a current density of 5 A / dm ² , and shown in Table 1. A Ni plating film having a film thickness was formed, pulled up from the plating bath, and washed with water.
Ni plating bath component Ni sulfate: 250 g / L
Ni chloride: 40 g / L
Boric acid: 35 g / L
Additive A: 3 ml / L
Additive B: 10 ml / L

(Formation of Ag plating film)
Sample No. About 14-18, the Ag plating film was formed as a base plating film in the said board | substrate. The same plating pretreatment as that for forming the Ni plating film was performed on the substrate. And sample no. For 14, 15 and 18, the surface of the substrate after pretreatment (entire surface) was a cyan bath with the following components and a liquid temperature of 15 ° C., and the counter electrode was an Ag (purity 99.99%) plate, and the current density was 5 A / dm. ^{In step 2} , bright Ag plating was performed to form an Ag plating film having a film thickness shown in Table 1, which was pulled up from the plating bath and washed with water.
Ag plating bath component Silver potassium cyanide (I): 50 g / L
Potassium cyanide: 40 g / L
Potassium carbonate: 35 g / L
Additive C: 3 ml / L

Sample No. 16 and 17, the surface of the substrate after pretreatment (entire surface) was an Ag-Bi alloy plating bath with a liquid temperature of 25 ° C and a Bi concentration of 100 mg / L, the counter electrode was a Pt plate, and the current density was 3 A / dm. ^In Step ² , Ag—Bi alloy plating was performed to form an Ag—Bi alloy plating film having a thickness shown in Table 1, which was pulled up from the plating bath and washed with water. Moreover, in order to analyze the composition of the Ag (Ag—Bi alloy) plating film, the plating film was formed under the same conditions using stainless steel 304 as a dummy substrate. The plating film is peeled off from the dummy substrate and dissolved in nitric acid, and then the dissolved nitric acid solution is analyzed using an ICP (inductively coupled plasma) emission spectroscopic analyzer (ICPS-8000, manufactured by Shimadzu Corporation) to obtain a composition. Asked.

  The thicknesses of the Ni plating film and the Ag plating film were controlled by adjusting the plating energization time based on the plating speed. Specifically, the dummy substrate was plated for a certain period of time under the same conditions as those of the respective plating. And about Ni plating film and Ag (pure Ag) plating film, the adhesion amount of Ni and Ag was calculated | required by measuring the weight difference with before plating of a dummy board | substrate, and this adhesion amount was calculated for plating area, Ni, Ag. The Ni plating film thickness (plating speed) deposited per unit time was calculated by dividing by theoretical density and plating time. For the Ag (Ag—Bi alloy) plating film, the plating rate was calculated by measuring the thickness of the plating film of the dummy substrate by cross-sectional SEM observation. For each base plating film, the plating time for forming a desired film thickness was calculated from the plating rate.

(Reflection film, noble metal film)
A reflective film and a noble metal film were formed by the following method on the substrate or the substrate on which the base plating film was formed. The substrate was placed in a chamber of a sputtering apparatus provided with a metal target (diameter 10.16 cm (4 inches φ) × thickness 5 mm) matched to the composition of the reflective film and the noble metal film shown in Table 1. Next, the chamber was evacuated with a vacuum pump so that the pressure in the chamber was 1.3 × 10 ⁻³ Pa or less, and Ar gas was introduced into the chamber to adjust the pressure in the chamber to 0.27 Pa. In this state, sputtering is performed by sequentially applying a DC voltage (output 100 W) to the metal target for the reflective film and the metal target for the noble metal film, and the two layers of the reflective film and the noble metal film shown in Table 1 are formed. A metal film was formed to prepare a sample of lead frames 1 and 1B. Sample No. 19 and 22 formed only the reflective film.

(Measurement of film thickness of reflective film and noble metal film)
Each film thickness of the reflective film and the noble metal film was measured by performing X-ray photoelectron spectroscopy (XPS). Using the fully automated X-ray photoelectron spectrometer (Physical Electronics Quantera SXM) for the surface of the sample, the metal elements contained in the noble metal film shown in Table 1, Al contained in the reflective film, and the substrate Each concentration of Cu or Ni and Ag of the underlying plating film was measured from the surface in the depth direction. The thickness from the sample surface to the depth at which the concentration of the metal element contained in the noble metal film is reduced to ½ of the maximum concentration is defined as the film thickness of the noble metal film, and from the depth, the concentration of Al is halved to the maximum concentration. The thickness up to the reduced depth was taken as the thickness of the reflective film. Measurement conditions were as follows: X-ray source: monochromatic Al—Kα, X-ray output: 43.7 W, X-ray beam diameter: 200 μm, photoelectron extraction angle: 45 °, Ar ⁺ sputtering rate: about 0.6 nm / in terms of SiO ₂ Minutes.

[Evaluation]
The obtained lead frame samples were evaluated for surface reflectance, resistance to sulfidation, wire bonding, and solderability by the following methods. The results are shown in Table 1.

(Reflectance evaluation)
Using an automatic absolute reflectance measurement system (manufactured by JASCO Corporation), the spectral reflectance at a wavelength of 250 to 850 nm was measured under the conditions of an incident angle of 5 ° and a reflection angle of 5 ° to obtain a regular reflectance. A regular reflectance of 50% or more was considered acceptable.

(Sulfuration resistance evaluation)
As a sulfidation resistance test, a sample was exposed for 96 hours in a chamber adjusted to a hydrogen sulfide concentration of 3 ppm, a temperature of 40 ° C., and a humidity of 80%. After the test, the regular reflectance was measured in the same manner as described above, and a test piece in which the decrease in regular reflectance by the sulfidation resistance test was less than 10 points was accepted.

(Wire bonding test)
Using a manual bonder (Model 4127, manufactured by KULICKE and SOFFA INDUSTRIES) between the lead members 1a and 1c shown in FIG. 4B (inner lead part, see FIG. 2B) Gold (pure Au) wire (manufactured by Tanaka Kikinzoku Kogyo) was wire bonded as a bonding wire. Then, the test was conducted by grasping and pulling the center of the gold wire with tweezers while observing with an optical microscope. As a result, when the gold wire can be cut without peeling from the bonding portion of the sample, “○” is given as the wire bonding property being good, and when the gold wire is peeled from at least one bonding portion. It was evaluated as “x” as being defective. In addition, the gold wire was not crimped to the surface of the sample, and the case where wire bonding could not be performed was evaluated as “XX” as being defective.

(Solderability evaluation)
The sample was heated to 250 ° C. with a hot plate, and a solder ball (Sn-3.0 at% Ag-0.5 at% Cu) having a diameter of about 5 mm was melted and dropped on the surface of the sample. It was removed and cooled to solidify the solder. And the wet contact angle in the sample surface of the solidified solder droplet was measured. As shown in FIG. 7, the sample is observed in a side view (viewed from a direction horizontal to the surface of the sample), and a line segment (indicated by a broken line in the figure) connecting the end point and the apex of the solder droplet is the sample surface. The angle θ was measured, and 2θ was assumed to be the wet contact angle of the solder droplets. The smaller the wet contact angle 2θ of the solder droplet is, the better the wettability of the solder is (see FIG. 7A). As the wet contact angle 2θ is increased, the wettability of the solder is lowered (see FIG. 7B). ). If the wetting contact angle 2θ is 80 ° or less, solder wettability is sufficient and mounting by soldering is possible. Therefore, the solderability is acceptable, and in particular, 2θ <45 ° is defined as excellent solderability. “◎” and 45 ° ≦ 2θ ≦ 80 ° were evaluated as “◯” as good solderability. On the other hand, when the wet contact angle 2θ exceeds 80 °, mounting by soldering becomes difficult, and 80 ° <2θ ≦ 90 ° is evaluated as “Δ”, and 2θ> 90 ° is evaluated as “×”.

  As shown in Table 1, sample no. Examples 1 to 18 are examples of the lead frame according to the present invention in which a noble metal film is coated on a reflective film made of Al or an Al alloy, and thus show excellent sulfidation resistance and good wire bonding and solderability. It was. In particular, sample No. 1 in which a Ni plating film or an Ag plating film was provided on the base of the reflective film. Nos. 9 to 18 also had high initial reflectivity and excellent light extraction efficiency.

  In contrast, sample no. Since No. 19 was provided with only an Ag film as a reflective film, the initial reflectivity was high, but the Ag film was significantly deteriorated by the sulfidation resistance test, and the reflectivity was lowered. Similarly, sample No. 1 in which an Ag film is used as a reflection film and a noble metal film is provided thereon. In No. 20, the hydrogen sulfide atmosphere entered from the pinhole of the noble metal film in the sulfidation resistance test, and the Ag film deteriorated. Sample No. No. 21 was insufficient in the thickness of the reflection film, and even when a Ni plating film was provided on the base, a sufficient initial reflectance could not be obtained.

  Sample No. In Nos. 22 and 23, since the reflective film was within the scope of the present invention, good initial reflectivity and sulfidation resistance were obtained. No. 22 is not provided with a noble metal film, so that a natural oxide film is formed on the reflection film surface. In No. 23, since the film thickness of the noble metal film was insufficient, the gold wire was not crimped and wire bonding could not be performed, or the solderability was lowered. On the contrary, sample No. In No. 24, since the noble metal film was excessive, the initial reflectivity was lowered. Sample No. In No. 25, since a Cu film was provided on the surface instead of the noble metal film, the Cu film was deteriorated by a sulfidation resistance test, and the reflectance was lowered.

[Sample preparation]
By changing a part of the manufacturing method from Example 1, samples of lead frames 1 and 1B having a laminated structure shown in FIGS. 1A and 1B were manufactured.

  Preparation of substrate and sample No. The Ni plating film 28 having a thickness of 0.5 μm was formed in the same manner as in Example 1. Further, an Al film having a film thickness of 150 nm was used as the reflective film. After forming a film with a sputtering apparatus under the same conditions as in No. 1, the chamber was once opened. Next, similarly to the formation of the reflection film, the inside of the chamber is evacuated again, Ar gas is introduced to adjust the pressure in the chamber to 0.27 Pa, and a Pd film having a thickness of 20 nm as a noble metal film is then formed. Sample No. 1 of Example 1. Films were formed under the same conditions as in Example 1, and samples of lead frames 1 and 1B were produced. Sample No. For No. 26, after adjusting the pressure in the chamber and before forming the noble metal film (Pd film), a DC voltage (output 100 W) was applied to the substrate for 3 minutes to remove the surface layer of the reflective film.

[Measurement and evaluation]
With respect to the obtained lead frame sample, the surface reflectance, sulfuration resistance, wire bonding property, and solderability were evaluated in the same manner as in Example 1. The results are shown in Table 2. Table 2 shows the sample No. 1 of Example 1. The results of 1 and 10 are also shown.

  As shown in Table 2, sample no. No. 26 is a sample No. 26 having the same laminated structure without continuously forming a reflective film and a noble metal film. The initial reflectivity and sulfidation resistance comparable to 1 were obtained. Furthermore, sample no. 26, since the natural oxide film formed on the surface of the reflection film is removed by removing the surface layer of the reflection film before the noble metal film is formed, the noble metal film has good adhesion on the reflection film (Al film). Sample No. As in the case of No. 1, good wire bonding and solderability were obtained, and it was confirmed that the lead frame according to the present invention could be manufactured. In contrast, sample no. Sample Nos. 27 and 28 each have the same laminated structure. The initial reflectivity and sulfidation resistance comparable to those of 1 and 10 were obtained, but the adhesion was inferior because the noble metal film was formed on the natural oxide film formed on the surface of the reflective film. As a result, although wire bonding was possible, the gold wire peeled off from the sample in the tensile test, and when the bonding site was observed with a scanning electron microscope (SEM), peeling occurred at the interface between the noble metal film and the reflective film. It was confirmed that Furthermore, sample no. In Nos. 27 and 28, the wettability of the solder decreased because the noble metal film on the surface was melted by contact with the solder droplets and the oxide film was exposed. From these, it can be seen that it is desirable that there is no oxide film between the noble metal film and the reflective film.

10, 10A Lead frame with support member 10B, 10C Lead frame with support member (LED lead frame)
1a, 1c Lead member 1, 1B Lead frame (LED lead frame)
11, 11A Substrate 12 Base plating film (Ni plating film, Ag plating film)
13 Reflective film 14 Noble metal film 2, 2A, 2B, 2C Support member 21 Resin molded body (base)
22 LED chip mounting part (recess)
23 Reflecting film 28 Spacing region

Claims (7)

  Select from a substrate made of copper or a copper alloy, a reflective film made of aluminum or an aluminum alloy formed on at least one side of the substrate and having a film thickness of 50 nm or more, and Pd, Au, Pt formed on the reflective film And a noble metal film having a film thickness of 5 nm or more and 50 nm or less made of one or more kinds. A support member having a recessed portion opened upward for accommodating the LED chip; and a pair of lead members supported by the support member, the pair of lead members being spaced apart from each other. An LED lead frame with a support member disposed on the bottom surface of the recess, each extending from the recess to the outside of the support member,
The support member includes a base made of an insulating material, and a reflective film having a thickness of 50 nm or more made of aluminum or an aluminum alloy formed in a region excluding the separation region on the surface of the recess,
The lead member includes a substrate made of copper or a copper alloy, a reflective film made of aluminum or an aluminum alloy formed on the substrate inside the recess, and a Pd formed on the reflective film. , Au, Pt, and a noble metal film having a film thickness of 5 nm to 50 nm.   The Ni plating film with a film thickness of 0.5 micrometer or more or the Ag plating film with a film thickness of 0.1 micrometer or more is further provided between the said board | substrate and the said reflecting film, The Claim 1 or Claim 2 characterized by the above-mentioned. LED lead frame.   On a substrate made of copper or a copper alloy, an evaporation source made of aluminum or an aluminum alloy and an evaporation source made of one or more selected from Pd, Au, and Pt are sequentially used by a physical vapor deposition method, A method of manufacturing a lead frame for LED, wherein a noble metal film is continuously formed. An aluminum film forming step of forming a reflective film on a substrate made of copper or a copper alloy by a physical vapor deposition method using an evaporation source made of aluminum or an aluminum alloy;
After removing the natural oxide film formed on the surface of the reflective film, a noble metal film forming step of forming a noble metal film using an evaporation source composed of one or more selected from Pd, Au, and Pt by physical vapor deposition And a method for manufacturing an LED lead frame. Before forming the reflective film, an insulating material is further used to form a base of the support member having a concave portion opened upward, and a base molding step is performed.
In the base body molding step, the base body is integrally molded so that the substrate is disposed as a pair of lead members on the bottom surface of the concave portion with a separation region therebetween,
6. The method for manufacturing an LED lead frame according to claim 4, wherein the reflective film is formed on the substrate at the same time as a region excluding the separation region on the surface of the recess.   7. The plating process of further forming a Ni plating film or an Ag plating film on the substrate by plating before forming the reflective film. The manufacturing method of the lead frame for LED described in the term.

Images