JP2016106423A - Method of manufacturing lead frame for led - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a lead frame for mounting an LED element having a high reflectance, preventing deterioration of insulation properties due to ion migration of silver used as a reflection layer and conductive layer, also having a high resistance against corrosive gas, and capable of suppressing deterioration in reflectance due to pileup of the copper when there is copper below the reflection layer.SOLUTION: In the manufacturing of a lead frame for LED for mounting an LED element, a lead frame 10 having a mounting surface for mounting the LED element of the lead frame 10 is prepared, a silver reflective layer 13 is provided as a reflective layer containing silver or a silver alloy on the mounting surface side of the lead frame 10. Subsequently, a protection material 14 is formed so that a part of the silver reflective layer 13 is exposed and the grain boundary of silver, exposed to the surface of the silver reflective layer 13, is reduced by the partially covered part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an LED lead frame on which an LED (light emitting diode) element is mounted.

  In recent years, an optical semiconductor device in which an LED element is mounted on a substrate or a lead frame is used for a backlight of a display device, a display lamp of various electric and electronic devices, an in-vehicle illumination, a general illumination, and the like. In general, such an optical semiconductor device has a structure in which an LED element is mounted and bonded on a heat-dissipating lead frame such as a copper base material, and then sealed by embedding the LED element with a translucent resin. Have.

  As an optical semiconductor device having such a structure, for example, a predetermined concave portion (reflector portion) is formed by pressing the copper base material on which the copper wiring layer is formed from the copper wiring layer side, and the inside of the concave portion ( It is known that an LED element is mounted on an element mounting portion) and then sealed with a translucent resin such as an epoxy resin or a silicone resin (see Patent Document 1). Such an optical semiconductor device includes a silver plating layer provided on the copper wiring layer and serving as a reflection layer in order to efficiently extract light emitted from the LED element.

  In the optical semiconductor device having such a structure, silver has excellent reflectivity and plays a role as a reflective layer, and also has excellent conductivity as a material for forming an electrode. On the other hand, silver is a metal that easily undergoes ion migration. In particular, in an optical semiconductor device in which an LED element that is driven by direct current is mounted as a light-emitting element, there is a problem that the insulating property deteriorates in the vicinity of the electrode. It is known that the progress of ion migration is promoted at a high temperature, and the progress is promoted by the presence of water molecules.

  Furthermore, as a translucent resin as a sealing agent used for sealing of such an optical semiconductor device, a silicone resin or the like is used, and although there is a difference in degree depending on the type of resin, gas barrier properties are not sufficient, Water molecules cannot be sufficiently blocked, and an increase in temperature at the time of light emission of the LED element is combined with deterioration of insulating properties due to silver ion migration over time.

  Furthermore, corrosive gases such as hydrogen sulfide in the air may permeate into the silver plating layer as the reflective layer over time. When such a corrosive gas comes into contact with the silver plating layer, there is a problem that the silver plating layer is discolored and the reflectance is significantly reduced.

  In order to solve such problems, conventionally, there has been proposed an optical semiconductor device in which a silver alloy or a metal oxide layer of a metal other than silver is provided on the outer layer of a silver alloy or silver layer on a substrate. (See Patent Document 2).

  In the optical semiconductor device disclosed in Patent Document 2, since the metal oxide layer is provided so as to cover the entire surface of the silver alloy or silver layer, corrosive gas such as oxygen or hydrogen sulfide in the air. It is possible to suppress the discoloration of silver due to. However, the reflectance in the optical semiconductor device depends on the reflectance of the metal oxide layer. Further, the metal oxide has a lower visible light reflectance than a silver alloy or silver. Accordingly, the reflectance in the initial stage of manufacturing the optical semiconductor device, that is, the reflectance in the initial stage before the layer made of silver alloy or silver is discolored by a corrosive gas or the like is lowered, and the light emitted from the LED element is efficiently extracted. There is a problem that the brightness of the optical semiconductor device is lowered.

  On the other hand, a metal oxide layer may be provided so as to expose a part of a layer made of silver alloy or silver in the optical semiconductor device disclosed in Patent Document 2 so as not to reduce the reflectance in the initial stage of manufacture. Conceivable. Although it is possible to improve the reflectivity at the initial stage of manufacture of the optical semiconductor device with such an embodiment, it is resistant to a corrosive gas or the like if the silver alloy or the layer made of silver is partially exposed. There is a problem that a part of the exposed silver alloy or silver layer is discolored. That is, no optical semiconductor device has been proposed that can satisfy the requirements of improving the reflectivity at the initial stage of production and improving the resistance of the silver alloy or silver layer to corrosive gas.

  In addition, when the optical semiconductor device is used for a long period of time, a so-called pile-up phenomenon may occur in which copper contained in the lead frame moves and accumulates toward the surface of the reflective layer due to heat or the like. When copper moves toward the surface of the reflective layer and accumulates due to this pile-up phenomenon, the reflective layer is colored by the accumulated copper. Furthermore, there is a problem that copper oxide is generated by the bond between the copper and oxygen, and the reflectance in the optical semiconductor device is significantly reduced. Further, when a copper pile-up phenomenon occurs in the manufacturing process, there is a problem in that the bonding strength is lowered during wire bonding due to copper oxide formed on the surface, and connection failure is likely to occur.

  Conventionally, an optical semiconductor device in which an intermediate plating layer such as a nickel plating layer is provided between a base material and a silver plating layer for the purpose of preventing a decrease in reflectance due to the copper pile-up phenomenon. It has been proposed (see Patent Document 3). However, the effect of suppressing the pileup (accumulation) on the surface of the reflective layer due to the movement of copper by the nickel plating layer is not sufficient, and the copper in the substrate piles up (accumulates) through the nickel plating layer over time. As a result, there is a problem that the reflectance is lowered.

JP 2006-245032 A International Publication 2011/004711 JP 2011-204790 A

  In view of the current situation as described above, the present invention has a high reflectivity at the initial stage of production, prevents a decrease in insulation due to ion migration of silver used as a reflective layer and a conductive layer, and is resistant to corrosive gases and the like. And a lead frame manufacturing method for mounting an LED element capable of effectively suppressing a decrease in reflectance due to pile-up of the copper when copper is present below the reflective layer. And

  In view of the above situation, earnest research and development is proceeding. Claim 1 of the present invention relates to a lead having a mounting surface on which the LED element of the lead frame is mounted in the manufacture of an LED lead frame on which the LED element is mounted. Preparing a frame, providing a silver reflective layer as a reflective layer containing silver or a silver alloy on the mounting surface side of the lead frame, and then partially exposing the silver reflective layer and partially A part of the silver reflective layer is exposed by the covered portion, and a grain boundary portion of silver exposed on the surface of the silver reflective layer is reduced by the partially covered portion. A lead frame manufacturing method is characterized in that a protective substance is formed.

  In addition, in the method for manufacturing an LED lead frame according to claim 2 of the present invention, before the treatment of partially covering the silver reflective layer with the protective substance, the silver reflective layer is subjected to heat treatment to form grain boundaries. The lead frame manufacturing method is characterized in that it is reduced.

  Here, reducing the silver grain boundary exposed on the surface of the silver reflective layer includes a concept including a state in which the protective metal exists on the silver grain boundary exposed on the surface of the silver reflective layer. It is. The state where the protective metal is present only in the silver grain boundary exposed on the surface of the silver reflective layer is desirable, but only the state present only in the silver grain boundary exposed on the surface of the silver reflective layer is shown. It is not a term used in meaning. It is a term used as a concept indicating a state in which a certain ratio of the portion covered with the protective metal is a grain boundary portion of silver exposed on the surface of the silver reflecting layer.

  In addition, in the LED lead frame manufacturing method according to claim 3 of the present invention, the process of partially covering with the protective member is performed by using a metal having a lower standard electrode potential than silver and a lower Young's modulus than silver. And forming a protective metal by a plating method.

According to the present invention, on the surface of the silver reflection layer, the exposed portion of the grain boundary portion where the reflectance is low and the silver alloy or silver crystal defects, precipitated impurities, and diffused or piled-up metal are concentrated is protected. Decreased by being covered with the use material. Therefore, the reflectivity is high at the initial stage of manufacture, the deterioration of the insulating property due to the ion migration of silver used as a reflective layer and a conductive layer is prevented, and the resistance to corrosive gas is high, and further, below the silver reflective layer. When copper is present, the effect of effectively suppressing the decrease in reflectance due to the pile-up of the copper becomes more remarkable.

Furthermore, by providing the structural requirements according to claim 2, by heat-treating the silver reflective layer before the treatment partially covered with a protective substance, silver alloy or silver crystal particles grow greatly, Grain boundaries exposed on the surface of the silver reflective layer are reduced.
On the surface of the silver reflective layer, the area of the non-grain boundary part (silver alloy or silver crystal part) having excellent reflectivity and low reactivity is relatively increased.For example, the standard electrode potential is lower than silver, and silver Since the area of the grain boundary part that needs to be covered with a protective material made of a metal having a lower Young's modulus is reduced, the deterioration of the insulation due to ion migration of the same silver is prevented, and the resistance to corrosive gases is also provided. In addition, when copper is present below the reflective layer, it is possible to form a silver reflecting surface with higher reflectivity while maintaining the effect of reducing the reflectivity due to the pile-up of the copper. In addition, it is possible to reduce the amount of metal that has a relatively large amount of expensive metal, has a lower standard electrode potential than silver, and has a lower Young's modulus than silver, and is effective in reducing costs.

  4. A metal lead comprising a LED lead frame on which an LED element is placed, wherein the silver reflective layer is partially covered so that a part of the silver reflective layer is exposed by providing the constituent elements according to claim 3. However, since the standard electrode potential is lower than that of silver, instead of silver ionizing silver, a metal having a lower standard electrode potential than silver is ionized, so that it acts as a so-called sacrificial metal and ionizes silver. prevent. Furthermore, the metal formed by partially covering the silver reflective layer so that a part of the silver reflective layer is exposed causes stress relaxation by using a metal having a Young's modulus lower than silver, and the silver reflective layer Prevents generation of fine cracks on the layer surface. Accordingly, the occurrence of fine cracks on the surface of the silver reflecting layer prevents the reflectance from decreasing and the reaction surface of silver from increasing.

  Further, a protective metal made of a metal having a standard electrode potential lower than that of the silver and a Young's modulus lower than that of the silver is deposited from the grain boundary exposed on the surface of the silver reflecting layer having high reactivity by plating. Therefore, the silver alloy or silver grain boundary exposed on the silver reflecting surface can be more selectively covered. Further, since the protective metal is formed from a highly reactive site, the silver reflective layer after the protective metal is formed by a plating method is chemically very stable. On the other hand, since the protective metal is selectively formed from highly reactive sites, the protective metal formation sites can be minimized and exposed to the surface of the silver reflective layer contributing to reflection. The area of the silver alloy or silver crystal part to be increased can be increased, and a silver reflecting surface having a high initial reflectance can be formed.

It is a fragmentary sectional view of CC cross section of FIG. 2 which shows the lead frame for LED which concerns on one Embodiment of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is a partial top view which shows the surface (LED element mounting surface) side of the lead frame for LED which concerns on one Embodiment of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is the elements on larger scale of the silver reflective layer before partially covering with the protective metal in this invention, FIG. 3 (A) is a partial top view which shows the surface (LED element mounting surface) side of the said silver reflective layer. FIG. 3B is a partial cross-sectional view showing a cross section of the silver reflective layer DD in FIG. It is the elements on larger scale of the silver reflective layer after partially covering with the protective metal in this invention, FIG. 4 (A) is a partial top view which shows the surface (LED element mounting surface) side of the said silver reflective layer. FIG. 4B is a partial cross-sectional view showing a cross section of the silver reflective layer EE in FIG. FIG. 5 is a process flow diagram seen from a cross-section corresponding to the CC cross section of FIG. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is sectional drawing which shows the optical semiconductor device in one Embodiment (the 1) of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is sectional drawing which shows the optical semiconductor device in other embodiment (the 2) of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is sectional drawing which shows the optical semiconductor device in other embodiment (the 3) of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is sectional drawing which shows the optical semiconductor device in other embodiment (the 4) of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is sectional drawing which shows the optical semiconductor device in other embodiment (the 5) of this invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. It is a process flow figure (the first half) which shows the form and manufacturing process of the sample for evaluation of silver ion migration in the present invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. (A-1) in a figure is corresponded in the base material in this application, (a-2) is sectional drawing in the FF cross section of (a-1). (B-1) in the figure corresponds to the base material in the present application in which a silver reflective layer is formed, and (b-2) is a cross-sectional view taken along the line GG in (b-1). (C-1) in the figure corresponds to a lead frame in which a protective metal is formed after forming a silver reflective layer on the substrate in the present application, and (c-2) is in the HH cross section of (c-1). It is sectional drawing. FIG. 3 is a process flow diagram (second half) showing the form and manufacturing process of a sample for evaluating silver ion migration in the present invention. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. (D-1) in the figure corresponds to the lead frame in the present application formed with an insulating resin, and (d-2) is a cross-sectional view taken along the line II of (d-1). (E-1) in the figure corresponds to the case where an insulating resin is formed on the lead frame in this application and then the sealing resin part is formed. (E-2) is a cross section taken along the line JJ of (e-1). FIG. (F-1) in the figure corresponds to a trimmed version of the lead frame in this application in which an insulating resin is formed and then a sealing resin portion is formed. (F-2) is a K- in (f-1). It is sectional drawing in a K cross section. It is a process flow figure showing a form and a manufacturing process of a comparative sample of silver ion migration. In this drawing, the protective metal is described as a layer for convenience. However, as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. The silver reflective layer is only partially formed on the face layer while being partially exposed. (A-1) in a figure is corresponded to the base material in this application, (a-2) is sectional drawing in the LL cross section of (a-1). (B-1) in the figure corresponds to a lead frame in which a protective metal is formed after forming a silver reflective layer on the substrate in the present application, and (b-2) is in the MM cross section of (b-1). It is sectional drawing. (C-1) in the figure corresponds to a trimmed version of the lead frame in the present application in which an insulating resin is formed and then a sealing resin portion is formed. (C-2) is an N- in (c-1). It is sectional drawing in a N cross section.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment at all, In the range of the objective of this invention, it can add and change suitably.

[LED lead frame]
First, the LED lead frame of the present invention will be described.
FIG. 1 is a partial cross-sectional view taken along the line CC of FIG. 2 showing an LED lead frame 10 according to an embodiment of the present invention. FIG. 2 is an LED lead according to an embodiment of the present invention. It is a partial top view which shows the surface (LED element mounting surface) side of a flame | frame. In FIG. 1, in order to explain the layer structure of the LED lead frame 10, for convenience, the cross section of the LED lead frame 10 is shown as a rectangular shape. In addition, the protective metal is described as if it is layered for convenience, but as will be described later, in reality, the protective metal is not a layer that uniformly covers the silver reflective layer. On the layer, a part of the silver reflection layer is exposed and only partially formed.

  As shown in FIGS. 1 and 2, the LED lead frame 10 according to the present embodiment has a mounting area MA (each area surrounded by a dotted line in FIG. 2) for mounting an LED element 11 (described later). A flat plate-like base material 12, a silver reflective layer 13 provided on at least the mounting region MA of the base material 12, and a silver reflective layer 13 provided on the silver reflective layer 13. A protective metal 14 made of a metal having a standard electrode potential lower than silver and a Young's modulus lower than silver, which is partially covered with the silver reflecting layer 13 so as to be exposed.

[Base material]
As the substrate 12, a conventionally known lead frame substrate can be used, for example, a metal substrate (conductive substrate) such as copper, copper alloy, 42 alloy (nickel 41% iron alloy), or A composite substrate or the like in which a conductive material layer is provided on the surface of an electrically insulating substrate such as ceramics or glass can be used. Among these, it is preferable to use a metal substrate (conductive substrate) from the viewpoint of heat dissipation of the substrate 12.

  As illustrated in FIGS. 7, 8, and 9, the reflector formation region RA is provided on the base material 12 so as to surround each placement region MA, and one reflector is provided in the reflector formation region RA. A groove 20 having a predetermined depth surrounding the outside of the placement area MA may be formed. The groove 20 is formed in the reflector formation region RA of the base material 12, for example, when the base material 12 is a metal base material and the resin reflector 16 is formed in the reflector formation region of the metal base material. The adhesion between the metal substrate and the resin reflector 16 can be improved. The depth, shape, and the like of the groove portion 20 can be appropriately set in consideration of the adhesiveness with the resin reflector 16 and the like.

  An insulating slit 19 is formed in the base material 12 so as to vertically cut (or cross) a plurality of placement areas MA arranged in parallel in the vertical direction (or horizontal direction). In the optical semiconductor device obtained by dicing and dividing the LED lead frame 10 by forming the insulating slit 19 that vertically cuts (or crosses) the mounting area MA, the mounting area MA has a large area. The first lead portion 21 and the second lead portion 22 having a small area can be divided so that the first lead portion 21 and the second lead portion 22 are electrically independent. The width in the short direction of the insulating slit 19 is not particularly limited, but can be appropriately set in the range of 200 to 600 μm, for example.

[Silver reflection layer]
The silver reflection layer 13 is a layer that plays a role of reflecting light emitted from the LED elements 11 mounted on the mounting area MA of the base material 12, and is silver or silver alloy (silver, tin, palladium, copper, gold, , An alloy containing other metal such as indium, rhodium, and zinc) is plated on at least the mounting region MA of the base material 12 by electroplating or the like and then heated at a predetermined temperature. In addition, content of the other metal in a silver alloy can be set in consideration of the melting temperature of a silver alloy, a reflectance, etc., for example, can be set to 50 mass% or less. From the viewpoint of realizing high reflectance and high conductivity, it is desirable that the purity of silver is high.

  The silver reflecting layer 13 formed by plating or the like promotes crystallization of silver alloy or silver by heat treatment, so that the silver alloy or silver grain boundary portion 52 exposed on the surface is relatively reduced, and ion migration. In addition, the resistance to corrosive gas and the like is high, and further, when copper is present below the silver reflection layer 13, the prevention effect against a decrease in reflectivity due to pile-up of the copper can be improved. Moreover, the improvement of a reflectance can be implement | achieved because the silver alloy or silver grain boundary part 52 exposed to the surface which should be covered with the protective metal 14 reduces.

The silver reflective layer 13 formed on the base material 12 in this way has a cross-sectional area of 1 μm, with 70% or more, preferably 85% or more and less than 100% of the total area of the predetermined cross section in the thickness direction. It is desirable to be occupied by ^two or more silver alloys or silver crystal particles 51. If the proportion of the silver alloy or silver crystal particles 51 having a cross-sectional area of 1 μm ² or more in the total area of the predetermined cross section in the thickness direction of the silver reflective layer 13 is within the above range, the silver alloy or silver in the silver reflective layer 13 As a result, the silver alloy or silver grain boundary portion 52 exposed on the surface of the silver alloy or silver grain boundary portion 52 is effectively reduced. Is sufficiently coated, so that the reflectivity in the initial manufacturing stage of the optical semiconductor device can be further improved, and the deterioration of the insulating property due to the ion migration of silver used as the reflective layer and the conductive layer is prevented, and the corrosion is prevented. In addition, when copper is present below the silver reflection layer 13, it is possible to effectively suppress a decrease in reflectance due to pile-up of the copper.

  In the present invention, the “predetermined cross section in the thickness direction of the silver reflecting layer 13” means observation using a SEM among the cut surfaces in the thickness direction of the silver reflecting layer 13 on the mounting region MA of the base material 12. A possible region, for example, a cut surface having a length of 10 μm × 20 μm in the thickness direction and the surface direction of the silver reflection layer 13. In the present invention, the “cross-sectional area of the silver alloy or silver crystal particle 51” means the area of the cut surface of the silver alloy or silver crystal particle 51 appearing in a predetermined cross section in the thickness direction of the silver reflective layer 13. The cross-sectional area can be measured by, for example, observing the cut surface using an SEM, discriminating crystal orientation using an EBSP detector, photographing a crystal particle image, and calculating a particle size distribution. .

  A crystal grain image by SEM of the silver reflection layer 13 in the present invention (especially when crystallization of silver alloy or silver is promoted by heat treatment) is typically as shown in FIG. When viewed from the surface, as shown in FIG. 3A, silver alloy or silver crystal particles 51 are observed, and between the silver alloy or silver crystal particles 51 and the silver alloy or silver crystal particles 51, A silver alloy or silver grain boundary 52 (also referred to as a crystal grain boundary) exposed on the surface can be observed. Further, “the predetermined cross section in the thickness direction of the silver reflective layer” which is a DD cross section in FIG. 3A is typically observed by SEM as shown in FIG. The area of the cut surface of the silver alloy or silver crystal particle 51 appearing in a predetermined cross section in the thickness direction can be calculated.

Further, the area ratio of the silver alloy or silver crystal particles 51 having a cross-sectional area of 1 μm ² or more in the total area of the predetermined cross section of the silver reflective layer 13 is an arbitrary plural number of the silver reflective layer 13 on one mounting region MA. A location (for example, 3 locations) is cut and can be calculated as an arithmetic average value of the area ratio in the cut surface.

  The thickness of the silver reflective layer 13 having such a configuration is not particularly limited, but can be preferably set to 1 to 10 μm, more preferably 1 to 5 μm, and particularly preferably 2 to 4 μm.

[Protective metal]
In the present invention, the silver reflective layer 13 is covered with the protective metal 14 so that a part of the silver reflective layer 13 is exposed. In addition, although the protective metal 14 in this embodiment is provided on the silver reflective layer 13 so that the silver reflective layer 13 may be exposed from a fine gap, it represents the fine gap in the cross-sectional view of FIG. Since it is extremely difficult, it is expressed as if the entire surface of the silver reflective layer 13 is covered with the protective metal 14 (the same applies to FIGS. 2 and 5 to 13).

  The material of the protective metal 14 is a metal having a lower standard electrode potential than silver from the viewpoint of preventing ionization of silver and further ion migration of silver by ionizing instead of silver as a sacrificial metal. Shows an excellent effect. On the other hand, in the case of a metal having a higher Young's modulus than silver, cracks due to stress occur, and the surface area of silver increases due to cracks on the silver surface, which facilitates the generation of silver ions. Absent. Therefore, the material of the protective metal 14 is required to be a metal having a standard electrode potential lower than that of silver and a metal having a Young's modulus lower than that of silver.

  Examples of metals having a lower standard electrode potential than silver and having a Young's modulus lower than silver include tin, lead, indium, bismuth, cadmium, aluminum, magnesium, calcium, and the like. However, there is a problem that a metal having a high reactivity is oxidized at the same time as formation or is difficult to form on the silver reflection layer 13. From the viewpoint of stability, safety, ease of handling, and ease of formation, tin, indium, and bismuth are preferable. These metals can be easily formed on the silver reflective layer 13 by a plating method, and can also enjoy the merits of the plating method described later.

  The formation of the protective metal 14 on the silver reflective layer 13 preferably has a property of partially covering the silver reflective layer 13 so that a part of the silver reflective layer 13 is exposed. At this time, as shown in FIG. 4, the protective metal 14 is provided on the silver reflective layer 13 so as to expose the silver reflective layer 13 from fine gaps.

  If the protective metal 14 is provided by coating the front surface of the silver reflective layer 13 on the film, the silver reflective layer 13 is not exposed, and silver ion migration can be suitably suppressed. In addition, it is possible to suppress a decrease in reflectance over time of the silver reflective layer due to hydrogen sulfide in the air. However, the reflectance at the initial stage of manufacture of an optical semiconductor device obtained from such an LED lead frame depends on the reflectance of the protective metal 14 which is inferior in reflectance to silver. Therefore, the reflectance is significantly smaller than that of an optical semiconductor device obtained from an LED lead frame having a highly reflective silver reflective layer exposed, leading to a reduction in the initial light emission luminance.

  However, if the silver reflective layer 13 is used without being covered with the protective metal 14, the silver ion migration will occur over time and the insulation will be deteriorated, so that the stability and reliability of the optical semiconductor device will be significantly reduced. . Further, it is difficult to ignore a decrease in reflectance of the silver reflecting layer 13 due to hydrogen sulfide in the atmosphere.

  In order to solve these problems, the present invention partially covers only a part of the silver reflective layer 13 with the protective metal 14 while leaving a part of the silver reflective layer 13 excellent in reflectivity. It has been found that by taking advantage of the high reflectivity of the silver reflective layer 13, it is possible to suppress deterioration of the reflectivity of the silver reflective layer 13 over time due to ion migration of silver and hydrogen sulfide in the air. It is.

Here, it is considered that the ionization of silver, which is a premise of the ion migration of silver, mainly occurs at a silver alloy or a crystal grain boundary of silver. Therefore, by providing the protective metal 14 so as to selectively cover the exposed silver alloy or silver grain boundary 52, silver ion migration in the silver reflective layer 13 can be effectively suppressed. It is considered a thing. However, in order to obtain a desired reflectance when the silver alloy or silver crystal particles 51 having a cross-sectional area of less than 1 μm ² occupy more than 30% of the total area of the predetermined cross-section of the silver reflecting layer 13. Even if the protective metal 14 is formed so that a part of the silver reflective layer 13 is exposed, the exposed silver alloy or silver grain boundary portion 52 cannot be sufficiently covered with the protective metal 14. In addition, it is difficult to suppress silver ion migration, and it is difficult to obtain a desired reflectance when the crystal grain boundary is sufficiently covered with the protective metal 14 to such an extent that silver ion migration can be suppressed. End up. On the other hand, the silver alloy or silver crystal particle 51 having a cross-sectional area of less than 1 μm ² is 30% or less of the total area of the predetermined cross-section of the silver reflective layer 13, so that the desired reflection on the silver reflective layer 13 is achieved. Even if the protective metal 14 is provided to such an extent that the reflectance can be obtained, the ion migration of the silver alloy or silver constituting the silver reflecting layer 13 can be suppressed, and as a result, the desired reflectance can be obtained. Can also be obtained.

  Moreover, it is considered that the silver alloy or silver corrosion caused by the corrosive gas is mainly caused by the silver alloy or silver crystal grain boundary as a starting point. Therefore, by providing the protective metal 14 so as to selectively cover the exposed silver alloy or silver grain boundary portion 52, the corrosion of the silver alloy or silver by the corrosive gas can be effectively suppressed. It is considered possible.

  In the optical semiconductor device manufactured using the LED lead frame 10 according to the present embodiment when the base material 12 (copper substrate, copper alloy substrate, etc.) containing copper is used as the base material 12 in the present embodiment. A so-called pile-up phenomenon may occur in which the copper contained in the base material 12 moves and accumulates toward the upper surface of the silver reflective layer 13 over time. At this time, when the copper contained in the base material 12 moves through the silver alloy or silver grain boundary 53 in the silver reflective layer 13 and the copper oxide formed by combining with oxygen is exposed on the surface of the silver reflective layer 13, The reflectance in the optical semiconductor device is lowered. However, according to the LED lead frame 10 according to the present embodiment, the protective metal 14 is provided so as to cover at least a part of the exposed silver alloy or silver grain boundary portion 52, thereby Copper that moves from the material 12 side can be prevented from reaching the surface of the silver reflective layer 13, and oxygen hardly enters along the silver alloy or silver grain boundary 53 from the surface side of the silver reflective layer 13. Therefore, it can suppress that copper oxide is produced | generated by the coupling | bonding of copper and oxygen, and can suppress the fall of the reflectance in an optical semiconductor device as a result.

  More desirably, as shown in FIG. 4 which is a schematic diagram when the state after the formation of the protective metal 14 on the silver reflection layer 13 is observed with an SEM, the surface is protected (FIG. 4A). The silver reflective layer exposed on the surface of the silver reflective layer 13 has excellent reflectivity by being formed so as to reduce the silver grain boundary portion 52 exposed on the surface of the silver reflective layer by the portion covered with metal. The exposed silver alloy or silver exposed to the surface of the silver reflective layer 13 is exposed to inferior reflectance and has high reactivity while leaving the silver alloy or silver crystal particles 51 having relatively low reactivity exposed. By covering the grain boundary portion 52 with the protective metal 14, the effect of suppressing the time-dependent decline in the reflectance of the silver reflecting layer 13 due to ion migration of silver and hydrogen sulfide in the air and the initial reflectance of the silver reflecting layer Extremely good effect on both heights She was found that the exhibit.

  The excellent formation of the protective metal 14 on the silver reflecting layer 13 as shown in FIG. 4 is achieved by an electrolytic plating method. The deposition of the protective metal 14 by the electrolytic plating method is formed from a highly reactive portion, that is, a silver alloy or silver grain boundary exposed on the surface of the silver reflective layer 13. A special plating method called “strike” or “flash”, which uses an electrolytic layer with a particularly high current density and low ion concentration, provides minute protection to exposed silver alloys or silver grain boundaries 52. The metal 14 can be deposited, and a coating that makes the best use of the exposed portion of the silver alloy or silver crystal particles 51 can be realized.

  The thickness of the protective metal 14 is preferably 5 to 50 nm, and more preferably 10 to 30 nm. If the thickness of the protective metal 14 is within the above range, silver ion migration, corrosion of the silver reflective layer 13 by corrosive gas (such as hydrogen sulfide), and coloring due to copper pileup can be effectively suppressed. it can. In the present embodiment, the thickness of the protective metal 14 is based on the plane including the exposed surface of the silver reflective layer 13 of the LED lead frame 10 according to the present embodiment and the plane including the uppermost surface of the protective metal 14. It means the distance in the vertical direction with respect to the material 12. The thickness of the protective metal 14 can be measured using a focused ion beam (FIB) apparatus, a fluorescent X-ray measurement apparatus, or the like.

  The LED lead frame 10 according to this embodiment includes a base plating layer (not shown) that improves the adhesion between the base material 12 and the silver reflective layer 13 between the base material 12 and the silver reflective layer 13. It may be. Examples of such a base plating layer include a copper plating layer and a nickel plating layer formed by electroless plating and electroplating. The thickness of the base plating layer can be appropriately set to 10 to 1000 nm, for example. The base plating layer has a function of improving the bondability between the base material 12 and the silver reflective layer 13.

  Moreover, between the base material 12 and the silver reflection layer 13, the copper plating layer and the silver plating layer may be laminated | stacked in order from the base material 12 side.

  Among these, the copper plating layer is used as a base layer for the silver plating layer, and has a function of improving the bondability between the silver plating layer and the substrate 12. The thickness of the copper plating layer is preferably 0.005 μm to 0.1 μm.

  The silver plating layer is used as a base layer for the silver reflection layer 13 and has a function of improving the bonding property between the copper plating layer and the silver reflection layer 13. In addition, it is preferable that the thickness of a silver plating layer is thicker than the silver reflection layer 13, for example, shall be 1 micrometer-5 micrometers. The silver plating layer may consist of either matte silver plating or bright silver plating. As described above, since the thickness of the silver reflection layer 13 is extremely thin, the profile of the silver plating layer can be exposed. For example, when the silver plating layer is made of matte plating, the surface of the silver reflection layer 13 can be made matte, and when the silver plating layer is made of glossy plating, the surface of the silver reflection layer 13 is also glossy. Can be tinged.

  A configuration in which these copper plating layer and silver plating layer are not provided is also possible. In this case, the LED lead frame 10 includes a base material 12 and a silver reflection layer 13 provided directly on the mounting surface of the base material 12.

If the silver reflective layer 13 is to be formed immediately above the nickel plating layer as the base plating layer, the silver reflective layer 13 may be easily peeled off. On the other hand, in consideration of adhesiveness with the silver reflective layer 13, when a copper strike plating layer is formed on the nickel plating layer or a silver strike plating layer is further formed on the copper strike plating layer, such LED is required. In the optical semiconductor device obtained from the lead frame 10 for copper, the copper pile-up phenomenon from the copper strike plating layer toward the surface of the silver reflection layer 13 may occur over time, and the reflectivity may decrease. is there. Moreover, although the nickel plating layer has an effect of suppressing copper pileup from the base material 12, if the thickness of the nickel plating layer is thin (about 10 to 200 nm), the effect of suppressing pileup is insufficient. Yes, copper moves from the substrate 12 toward the surface of the silver reflective layer 13. However, according to the LED lead frame 10 according to the present embodiment, the protective metal 14 is provided so as to cover the silver alloy or silver crystal grain boundary in the silver reflecting layer 13. In the optical semiconductor device obtained from the lead frame 10, even when the copper strike plating layer is formed on the nickel plating layer or when the nickel plating layer is thin, the lower part of the silver reflection layer 13 ( The copper that has moved from the base material 12 and the copper strike plating layer) can be prevented from moving to the surface of the silver reflective layer 13, and oxygen on the silver reflective layer 13 enters the silver reflective layer 13. Can be prevented. As a result, it is possible to suppress bonding between copper and oxygen, and it is possible to suppress a decrease in reflectance in the optical semiconductor device.

  In the LED lead frame 10 according to the present embodiment, a resin reflector 16 may be formed in the reflector forming area RA surrounding each mounting area MA (FIGS. 6, 7, 8, and 8). The resin reflector 16 may not be formed (see FIG. 1 and FIG. 10).

[LED lead frame manufacturing method]
The LED lead frame 10 having the above-described configuration can be manufactured as follows. FIG. 5 is a process flow diagram showing a manufacturing process of the LED lead frame 10 according to the present embodiment.

(Substrate patterning)
First, as shown in FIG. 5A, a base material 12 made of a flat metal base material is prepared. As the base material 12, for example, a metal base material made of copper, copper alloy, 42 alloy (Ni 40.5% to 43% Fe alloy) or the like can be used as described above. The thickness of the base material 12 is, for example, in the range of 0.05 mm to 0.5 mm. In addition, it is preferable to use what the base material 12 performed the degreasing | defatting etc. to the both surfaces, and performed the washing process.

    Next, the etching resist 41 is applied to the front and back surfaces of the substrate 12, dried, exposed through a desired photomask, and then developed to form the etching resist 41 (FIG. 5B). As the etching resist 41, a conventionally known resist can be used.

  Next, the etching resist 41 is used as an anticorrosion film, and the substrate 12 is etched with an etching solution (FIG. 4C). The corrosive liquid can be appropriately selected according to the material of the base material 12 to be used. For example, when copper is used as the base material 12, an aqueous ferric chloride solution is usually used and sprayed from both surfaces of the base material 12. It can be performed by etching.

  Next, the etching resist 41 is peeled and removed. Thus, the base material 12 which has a 1st part and a 2nd part spaced apart from the 1st part is obtained (FIG.4 (d)). At this time, the groove 20 may be formed on the surface of the substrate 12 by half etching.

  Next, the etching resist 41 is peeled and removed. Thus, the base material 12 which has a 1st part and a 2nd part spaced apart from the 1st part is obtained (FIG.4 (d)). At this time, the groove 20 may be formed on the surface (upper surface) of the LED lead frame 10 by half etching.

(Formation of silver reflective layer)
Next, a plating resist 42 having a desired pattern is provided on the front surface and the back surface of the base material 12 (FIG. 4E). Among these, the plating resist 42 on the surface side has an opening formed at a position corresponding to the formation site of the silver reflective layer 13, and the LED mounting surface 10 a of the base material 12 is exposed from this opening. On the other hand, the back side plating resist 42 covers the entire back surface of the substrate 12. The size, shape, and the like of the opening included in the plating resist 42 can be appropriately set according to the portion, shape, and the like of the silver reflective layer 13 to be formed.

  A metal is deposited on the base material 12 to form a silver reflection layer 13 (FIG. 4F).

  As described above, the silver reflection layer 13 is made of an alloy of platinum (Pt) and silver (Ag) or an alloy of gold (Au) and silver (Ag). Here, when the silver reflection layer 13 is made of an alloy of platinum and silver, the silver reflection layer 13 can be formed by sputtering, ion plating, vapor deposition, or the like of the alloy. On the other hand, when the silver reflecting layer 13 is made of an alloy of gold and silver, the silver reflecting layer 13 can be formed by electrolytic plating as the substrate 12 power feeding layer. In this case, as the plating solution for electrolytic plating, a silver plating solution mainly composed of silver cyanide, gold cyanide and potassium cyanide can be used. The thickness of the silver reflective layer 13 thus formed is preferably, for example, 1 to 10 μm, and more preferably 1 to 5 μm.

  Further, when forming a plating film containing silver as described above, for example, by performing electrolytic plating using a silver plating solution mainly composed of silver cyanide, a plating film is formed on the surface of the substrate 12. Can be formed. As a plating solution for electrolytic plating for forming a silver plating layer, a silver plating solution mainly composed of silver cyanide and potassium cyanide can be used. In addition, before forming the plating film, for example, an electrolytic degreasing process, a pickling process, and a copper strike process may be appropriately selected, and then the plating film may be formed through an electrolytic plating process. In this case, as a plating solution for electrolytic plating for forming a copper plating layer, a copper plating solution mainly composed of copper cyanide and potassium cyanide can be used.

  In addition, when providing a base plating layer under the silver reflective layer 13, before performing a silver plating process, a nickel plating of a base plating layer (a copper plating layer or predetermined thickness (about 10-200 nm) is carried out on the surface of the base material 12. A base plating layer forming step of forming a layer, a copper strike plating layer (thickness of about 50 to 200 nm) and a silver strike plating layer (thickness of about 50 to 200 nm) on them may be added if desired.

(Heating process)
Subsequently, the substrate 12 having the silver reflective layer 13 made of silver alloy or silver is heated. The heating temperature of the base material 12 is a temperature at which the size of the crystal particles can be increased by recrystallizing the silver alloy or silver crystal particles constituting the silver reflective layer 13, that is, the heating of the silver reflective layer 13 after heating. Heating temperature such that preferably 70% or more, more preferably 85% or more and less than 100% of the total area of the predetermined cross section in the thickness direction is occupied by silver alloy or silver crystal grains having a cross-sectional area of 1 μm ² or more. The heating temperature is such that at least one silver alloy or silver crystal particle having a cross-sectional area equal to or greater than the square of the thickness of the silver reflective layer 13 is present in the silver reflective layer 13 after heating. preferable. By heating at such a temperature, the silver reflective layer 13 with few silver alloy or silver crystal grain boundaries 53 can be formed. Specifically, heating at 200 to 500 ° C. is preferable, and heating at 300 to 450 ° C. is more preferable.

  Moreover, it is preferable that it is 1 to 10 minutes, and, as for the heating time of the base material 12, it is more preferable that it is 2 to 5 minutes. If the heating time of the substrate 12 is less than 1 minute, the size of the silver alloy or silver crystal particles constituting the silver reflective layer 13 may not be increased effectively, and even if it exceeds 10 minutes, It is difficult to further increase the size of the silver alloy or silver crystal grains and reduce the crystal grain boundaries 53.

  The substrate 12 is preferably heated in an inert gas atmosphere such as nitrogen. By heating the substrate 12 under an inert gas atmosphere, corrosion (oxidation) of the silver alloy or silver during heating can be further suppressed.

If the plating resist 42 can be removed by heating the substrate 12, the plating resist 42 is again exposed so that the silver reflective layer 13 is exposed before the protective metal 14 forming step described later. The plating resist 42 may not be provided. When the plating resist 42 is not provided, a plating layer made of a metal material constituting the protective metal 14 is also formed on the back surface side of the substrate 12 and the reflector forming region RA. Further, when the plating resist 42 cannot be removed by heating the base material 12, the plating resist 42 remains in the heated base material 12. What is necessary is just to transfer to a formation process.

(Protective metal formation process)
After the silver reflective layer 13 is formed on the surface of the substrate 12 by the heating process described above, a predetermined protective metal material (with a standard electrode potential lower than silver and silver) on the silver reflective layer 13 in a predetermined form. A protective metal 14 is formed by plating a metal having a lower Young's modulus (for example, any one of indium, bismuth, tin, or an alloy containing them) by an electroplating method or the like (FIG. 5). (G)). By forming the protective metal 14 by electroplating a predetermined metal material with a predetermined film thickness in this way, the protective metal 14 is formed so that a part of the silver reflective layer 13 is exposed. Can do. Thereafter, by removing the plating resist 42, the LED lead frame 10 according to the present embodiment can be manufactured (FIG. 5H).

  At this time, the protective metal preferably has a film thickness (distance in the direction perpendicular to the base material 12 between the plane including the exposed surface of the silver reflective layer 13 and the plane including the uppermost surface of the protective metal 14) of 5 to 50 nm. Particularly preferably, a predetermined metal material is plated so as to form a protective metal 14 having a thickness of 10 to 30 nm. If the film thickness of the protective metal 14 is less than 5 nm, it may be difficult to form the protective metal 14 that can effectively suppress the corrosion of the silver alloy or silver constituting the silver reflective layer 13. Yes, if the thickness exceeds 50 nm, the silver alloy or silver in the silver reflective layer 13 can be formed although the silver alloy constituting the silver reflective layer 13 or the protective metal 14 capable of effectively suppressing corrosion of silver can be formed. The protective metal 14 is also formed in portions other than the crystal grain boundaries, and the reflectance at the initial stage of manufacture of the optical semiconductor device obtained using the LED lead frame may be lowered.

By forming the protective metal 14 having a film thickness within the above range, the protective metal 14 is selectively formed at the silver alloy or silver crystal grain boundary 52 portion. In particular, by forming the protective metal 14 by electroplating, the silver alloy or silver grain boundary 52 has a higher current density than the other parts, and the silver alloy or silver grain boundary The protective metal 14 is easily selectively formed on the portion 52. As described above, in the heated silver reflection layer 13, since the silver alloy or silver grain boundary portion 52 constituting the silver reflection layer 13 is reduced, a part of the silver reflection layer 13 is exposed. Thus, even if the protective metal 14 is formed, the silver alloy or silver grain boundary 52 is hardly exposed. As a result, the silver ion migration in the silver reflective layer 13 can be effectively suppressed, and the corrosion of the silver reflective layer 13 by a corrosive gas or the like can be effectively suppressed. By using the lead frame 10, an optical semiconductor device having a good reflectance corresponding to the reflectance of silver alloy or silver constituting the silver reflecting layer 13 can be obtained.

Further, the size of the silver alloy or silver crystal particles 51 in the silver reflective layer 13 is increased by the heating step to reduce the silver alloy or silver grain boundary portion 52 exposed on the surface, and the protective metal 14 forming step is performed. In the optical semiconductor device manufactured using the LED lead frame 10 obtained by selectively forming the protective metal 14 on the exposed silver alloy or silver grain boundary 52 in the silver reflective layer 13, The copper that has moved from the lower side of the silver reflecting layer 13 (base 12, copper strike plating layer as the underlying plating layer) toward the surface is prevented from moving to the surface of the silver reflecting layer 13. In addition, oxygen on the silver reflective layer 13 can be prevented from entering the silver reflective layer 13 through the silver alloy or silver grain boundary 53. As a result, it is possible to suppress bonding between copper and oxygen, and it is possible to suppress a decrease in reflectance in the optical semiconductor device.

In addition, when the silver reflective layer 13 is formed using a silver alloy, even if the metal material which comprises the protective metal 14 mentioned above is an alloy containing the same metal seed | species as the silver alloy which comprises the said silver reflective layer 13 Good. For example, when the silver reflective layer 13 is formed of a silver indium alloy, the protective metal 14 may be formed using a silver indium alloy having a higher indium composition ratio than the silver indium alloy.

(Resin reflector forming process)
In addition, in the manufacturing method of the LED lead frame 10 according to the present embodiment, the resin reflector 16 that forms the resin reflector 16 in the reflector forming region RA surrounding the mounting region MA after the protective metal 14 forming step described above. A forming step may be further included (see FIGS. 6, 7, 8, and 9), or the resin reflector forming step may not be included (see FIG. 10). In the case of having such a resin reflector forming step, the step of forming the resin reflector in the reflector forming region RA of the LED lead frame 10 can be omitted in the optical semiconductor device manufacturing method described later.

[Optical semiconductor device]
Next, an optical semiconductor device using the LED lead frame 10 having the above-described configuration will be described. FIG. 6 is a cross-sectional view showing the optical semiconductor device 30 in the present embodiment.

  As the LED element 11 described above, for example, an LED element generally used in the past can be used. Here, the LED element 11 appropriately selects a material made of a compound semiconductor single crystal such as GaP, GaAs, GaAlAs, GaAsP, and AlInGaP or various GaN-based compound semiconductor single crystals such as InGaN as the light emitting layer. The emission wavelength from ultraviolet light to infrared light can be selected.

As shown in FIG. 6, the optical semiconductor device 30 in the present embodiment includes the base material 12 of the LED lead frame 10 and the reflector formation region RA of the base material 12 of the LED lead frame 10 described above. A reflector 16 provided so as to surround the mounting area MA and expose the mounting area MA, and an LED element mounted on the mounting area MA of the base 12 of the LED lead frame 10 11 and a sealing resin portion 17 in which a sealing resin is filled in a space surrounded by the reflector 16 in order to seal the LED element 11.

The resin material constituting the reflector 16 is not particularly limited as long as it is an electrically insulating material. For example, one or more of polyphthalamide, epoxy, silicone, liquid crystal polymer and the like are combined. Can be used. The insulating slit 19 of the substrate 12 is filled with the same resin material as that of the resin reflector 16.

In the present embodiment, the mounting area MA of the base material 12 is divided into a first lead portion 21 and a second lead portion 22 through an insulating slit 19, and a resin-made reflector 16 is configured in the insulating slit 19. The same resin material as that to be filled is filled. Thereby, the first lead portion 21 and the second lead portion 22 are electrically independent from each other.

  The bonding wire 15 is made of a material having good conductivity such as gold, copper, and aluminum, and the LED element 11 has one terminal (not shown) connected to the first lead portion 21 having a large area in the base 12. The other terminals are connected to the second lead portion 22 having a small area by the bonding wire 15 so as to be mounted on the mounting area MA.

The silver reflective layer 13 on the substrate 12 is divided into two by the insulating slit 19, and the first silver reflective layer 13 and the second silver reflective layer 13 formed on the surfaces of the first lead portion 21 and the second lead portion 22, respectively. It consists of a silver reflective layer 13, and each edge of the first silver reflective layer 13 and the second silver reflective layer 13 is opposed to each other through an insulating slit 19.

As the sealing resin constituting the sealing resin portion 17, a translucent resin that is generally used for sealing the LED element 11 in the optical semiconductor device 30 can be used. As the translucent resin according to the present invention, it is desirable to select a material having a high light transmittance and a high refractive index at the emission wavelength of the LED element 11 in order to improve the light extraction efficiency. For example, an epoxy resin or a silicone resin can be selected as a resin that satisfies the characteristics of high heat resistance, weather resistance, and mechanical strength. In addition, translucent resins such as epoxy resins and silicone resins, and those in which one or more of diffusing materials such as fluorescent substances, silica, alumina, titanium oxide are contained in the translucent resins, etc. Is mentioned. As such a translucent resin, it is preferable to use a silicone resin. The encapsulating resin constituting the encapsulating resin portion 17 of the optical semiconductor device 30 is exposed to heat due to heating during reflow soldering of the optical semiconductor device 30 or when the high brightness LED is used as the LED element 11. It is exposed to strong light emitted from the luminance LED. In this respect, the silicone resin is preferable because it is a resin material that hardly causes deterioration of translucency such as discoloration due to heat or light as compared with other translucent resins (epoxy resin or the like). On the other hand, the silicone resin has a lower gas barrier property than other translucent resins (such as an epoxy resin). However, in the LED lead frame 10 according to the present embodiment, silver ion migration and Corrosion of the silver reflecting layer 13 due to corrosive gas or the like is effectively suppressed. Therefore, in the optical semiconductor device 30 according to the present embodiment, even if a silicone resin having a low gas barrier property is used as the sealing resin constituting the sealing resin portion 17, the silver alloy or silver reflectance constituting the silver reflective layer 13 is used. It is possible to obtain a good reflectance according to the above.

The optical semiconductor device 30 in the present embodiment is preferably a device that can emit light having a wavelength of 400 to 700 nm. Light having a wavelength in this range tends to cause a decrease in reflectance due to corrosion of the silver reflection layer 13 of the optical semiconductor device 30. However, in the optical semiconductor device 30 in this embodiment, the protective metal 14 is provided so that a part of the silver reflective layer 13 is exposed, and the silver reflective layer 13 heats the silver plating layer, Since the exposed silver alloy or silver grain boundary 52 constituting the silver reflecting layer 13 is reduced by growing silver crystals, corrosion of the silver reflecting layer 13 is suppressed, and light The reflectance at the initial manufacturing stage of the semiconductor device 30 is also high. Therefore, in the optical semiconductor device 30 in the present embodiment, the reflectance of light having a wavelength of 400 to 700 nm can be maintained at a high level over time from the initial stage of manufacture.

The optical semiconductor device 30 in the present embodiment can be manufactured as follows.

  First, the LED lead frame 10 according to the present embodiment is prepared, and the resin reflector 16 is formed in the reflector forming region RA of the LED lead frame 10.

Next, one terminal of the LED element 11 is connected to the first lead portion 21 of the LED lead frame 10, and the other terminal of the LED element 11 is connected to the second lead portion 22 by the bonding wire 15.

  Then, a sealing resin is filled in a space surrounded by the resin reflector 16 on the mounting area MA on which the LED element 11 is mounted, and the sealing resin portion 17 that seals the LED element 11 and the bonding wire 15 is provided. Form. Then, the optical semiconductor device 30 separated into pieces can be obtained by dicing along a dicing line.

  The LED lead frame 10 constituting the optical semiconductor device 30 described above is capable of suppressing silver ion migration and effectively preventing corrosion of the silver reflective layer 13 due to corrosive gas or the like. Even if a silicone resin or the like having a low gas barrier property is used as the sealing resin constituting the portion 17, the silver alloy or silver ion migration and corrosion constituting the silver reflective layer 13 can be effectively prevented. Therefore, in the optical semiconductor device 30 according to the present embodiment, it is preferable to use a silicone resin that is unlikely to be discolored due to heat, light exposure, or the like as the sealing resin constituting the sealing resin portion 17.

  According to the optical semiconductor device 30 having the above-described configuration, in the LED lead frame 10 used for manufacturing the optical semiconductor device 30, the silver reflective layer 13 is exposed so that a part of the silver reflective layer 13 is exposed. Since the protective metal 14 is formed on the exposed crystal grain boundary, silver ion migration due to moisture in the air and corrosion of the silver reflective layer 13 due to corrosive gas are effectively suppressed, and the silver reflective layer 13 Good reflectivity corresponding to the reflectivity of the silver alloy or silver constituting the film can be obtained. Moreover, even if copper moves from below the silver reflecting layer 13 (base 12, copper strike plating layer as the base plating layer) over time, the copper moves to the surface of the silver reflecting layer 13. In addition, it is possible to prevent oxygen on the silver reflective layer 13 from entering the silver reflective layer 13. As a result, it is possible to suppress bonding between copper and oxygen, and it is possible to suppress a decrease in reflectance in the optical semiconductor device.

The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  In the above embodiment, the dicing line of the LED lead frame 10 is set so that one LED element 11 (mounting area MA) is included in one optical semiconductor device 30 to be separated. The number of LED elements 11 (mounting area MA) may be included in one optical semiconductor device 30 (for example, four).

  In the above embodiment, the mounting area MA in the LED lead frame 10 has a large area due to the insulating slit 19 that vertically cuts (or crosses) the mounting area MA in parallel with the vertical direction (or the horizontal direction) of the substrate 12. Although it is divided into the first lead portion 21 and the second lead portion 22 having a small area, the present invention is not limited to this. For example, the mounting region MA that is arranged in parallel in the vertical direction (or the horizontal direction) of the base material 12. The first lead portion 21 and the second lead portion 22 having substantially the same area may be divided by an insulating slit 19 that vertically cuts (or crosses) substantially the center. In this case, there is a form (FlipChipPackage) connected to the first lead portion 21 and the second lead portion 22 by solder, an adhesive having conductivity and heat conductivity, or the like, instead of the bonding wire. As shown in FIG. 8, the optical semiconductor device 30 obtained using the LED lead frame 10 has one terminal portion of the LED element 11 straddling the first lead portion 21 and the second lead portion 22. The first lead portion 21 may be connected, and the other terminal portion may be connected to the second lead portion 22.

  Further, as shown in FIG. 9, the mounting area MA has two parallel insulating slits 19, 19 that longitudinally (or cross) the mounting area MA parallel to the vertical direction (or horizontal direction) of the base material 12. Thus, it may be divided into first to third lead portions. In this case, the optical semiconductor device 30 obtained by using the LED lead frame 10 has the LED element 11 in the third lead portion 23 located in the center of the mounting area MA (between the two insulating slits 19, 19). Is mounted, one terminal portion of the LED element 11 is connected to the first lead portion 21, and the other terminal portion is connected to the second lead portion 22.

  Furthermore, in the above embodiment, a plurality of through holes may be formed along the dicing line of the LED lead frame 10. In the LED lead frame 10 having such a configuration, dicing when the LED lead frame 10 is diced into individual pieces in the process of manufacturing the optical semiconductor device 30 using the LED lead frame 10. The amount of metal to be reduced can be further reduced, and the load on the dicing blade can be further reduced. Further, when the substrate 12 is clamped using the upper mold and the lower mold, and the resin-made reflector 16 is formed in the reflector forming region RA by pouring the resin into the mold cavity and curing it, The resin can be distributed to all the cavities located in the reflector formation region RA through the through holes.

  Furthermore, in the above embodiment, a plating resist 42 having an opening of a predetermined shape corresponding to each mounting area MA of the base 12 is provided, and the silver reflective layer is formed on the base 12 exposed at the opening. However, the silver reflective layer 13 may be formed on the entire surface of the base material 12 without providing the plating resist 42.

  Moreover, in the said embodiment, although the optical semiconductor device 30 has the resin-made reflectors 16 which surround mounting area MA and expose mounting area MA, as shown in FIG. The base material 12 and one terminal (not shown) are connected to the large-area first lead portion 21 in the base material 12 of the LED lead frame 10, and the other terminals are connected to the small-area second lead portion 22. By being connected by the bonding wire 15, the LED element 11 that is mounted on the mounting area MA, and a sealing resin portion 17 that is configured by a sealing resin that covers the base material 12 and the LED element 11 are provided. You may not have the reflector 16 made from resin.

In addition, although not shown in the figure, a form in which two LED elements 11 are placed on the upper surface of one first lead portion and connected by bonding wires 15 is also possible.

The LED element 11 is generally fixedly mounted with solder or an adhesive having heat conductivity. Here, when a die bonding paste is used instead of solder, it is possible to select a die bonding paste made of a light-resistant epoxy resin or silicone resin. In addition, the first lead portion 21 of the LED element 11 using ACF (anisotropic conductive film), ACP (anisotropic conductive paste), NCF (nonconductive film), NCP (nonconductive paste), or the like, There is also a method of directly connecting to the second lead portion 22.

EXAMPLES Hereinafter, although an Example etc. are given and this invention is demonstrated further in detail, this invention is not limited to the following Example etc. at all.

[Example 1]
A copper plate having a thickness of 0.2 mm, a width of 60 mm, and a length of 50 mm was prepared as the substrate 12. After forming an etching resist 41 in a predetermined shape, an insulating slit 19 having the shape shown in FIG. 2 was formed by spray etching from both surfaces of the base material 12 using an aqueous ferric chloride solution. After the insulating slit 19 was formed, the etching resist 41 was peeled off and removed. The pitch of the mounting areas MA adjacent in the vertical direction is 3 mm, the pitch of the mounting areas MA adjacent in the horizontal direction is 4 mm, and the mounting is arranged in a matrix of 13 rows × 13 columns on the substrate 12. The insulating slit 19 was formed so as to provide the placement area MA.

  A plating resist 42 having an opening of a predetermined shape is formed on the mounting surface side of the LED element 11 of the base material 12 thus obtained, and insulating plating is applied to one surface of the other surface (back surface) side. A resist 42 was formed. And after performing strike plating (thickness 0.05 micrometer) of copper as a base layer on the base material 12 exposed through the opening part by the side of the mounting surface of the base material 12, silver plating is carried out by the electroplating method. An applied silver reflective layer 13 (thickness: 3 μm) was formed. Next, the base material 12 on which the silver reflective layer 13 was formed was heated at 400 ° C. for 2 minutes using a reflow furnace (product name: RN-CS, manufactured by Panasonic Corporation).

Subsequently, the protective metal 14 with a thickness of 10 nm made of tin so that a part of the silver reflective layer 13 is exposed by plating with a flash plating solution of tin on the silver reflective layer 13 formed as described above. After that, the resist 42 for plating was removed, and the LED lead frame 10 (Example 1) was produced. Specifically, the protective metal 14 by the tin plating is formed by forming a silver plating layer and heating the substrate 12 into a plating bath containing tin methanesulfonate (tin concentration: 2.0 g / L). It was formed by immersion for 1 minute, electroplating (current density: 10 mA / dm ² ), washing with water, and drying.

[Example 2]
In Example 1, by using a flash plating solution containing bismuth methanesulfonate instead of the tin flash plating solution, plating is performed on the silver reflective layer 13 so that a part of the silver reflective layer 13 is exposed by bismuth. A protective metal 14 having a thickness of 10 nm was formed, and then the plating resist 42 was removed to produce an LED lead frame 10 (Example 2). Specifically, the protective metal 14 by bismuth plating is formed by forming a silver plating layer and heating the substrate 12 into a plating bath (tin concentration: 5.0 g / L) containing bismuth methanesulfonate. It was formed by immersion for 1 minute, electroplating (current density: 15 mA / dm ² ), washing with water, and drying.

[Example 3]
In Example 1, the silver reflective layer 13 is plated using an indium flash plating solution instead of the tin flash plating solution, so that a part of the silver reflective layer 13 is exposed so that a thickness of 10 nm is protected by indium. The metal 14 was formed, and then the plating resist 42 was removed to produce the LED lead frame 10 (Example 3). Specifically, the protective metal 14 by indium plating is prepared by forming the silver plating layer and heating the base material 12 into a plating bath (indium concentration: 3.0 g / L) containing indium methanesulfonate. It was formed by immersion for 1 minute, electroplating (current density: 15 mA / dm ² ), washing with water, and drying.

[Comparative Example 1]
In Example 1, the plating flash was not applied with the tin flash plating solution. Therefore, the plating resist 42 was removed without forming the protective metal 14 on the surface of the silver reflecting layer 13, and the LED lead frame (Comparative Example). 1) was produced.

One mounting area out of the mounting areas MA in the LED lead frame 10 of Example 1, Example 2, and Example 3 and the LED lead frame of Comparative Example 1 formed as described above. MA was arbitrarily selected, and the silver plating layer on the placement area MA was cut at three arbitrarily selected locations. Then, the three cut surfaces were observed using an SEM (manufactured by JEOL Ltd., product name: JSM-7001F), and an EBSP detector (TSL, condition: inclination 70 degrees, acceleration voltage 15 kV, applied current). The crystal orientation was determined using 10 nA, a range of 20 μm × 3 μm, a crystal grain image was taken, and the cross-sectional area of silver crystal particles in the cross section of the silver plating layer was measured by a method of calculating the particle size distribution.

As a result, the LED lead frame 10 produced in Example 1, Example 2 and Example 3 and the LED lead frame in Comparative Example 1 were all of the cut surface in the thickness direction of the silver plating layer. The area ratio (arithmetic average value of the area ratios at three cut surfaces) of silver crystal grains having a cross-sectional area of 1 μm ² or more in the area was 96%. The maximum cross-sectional area of the silver crystal particles appearing on the cut surface (the arithmetic average value of the maximum cross-sectional areas of the silver crystal particles at each of the three cut surfaces) was 35 μm ² .

  In addition, one mounting area MA is arbitrarily selected from the mounting areas MA in the LED lead frame 10 manufactured in Example 1, Example 2, and Example 3, and the mounting area MA is selected. When the surface of the upper silver reflection layer 13 was observed using an SEM (manufactured by JEOL Ltd., product name: JSM-7001F), the lead frames for LEDs produced in Example 1, Example 2, and Example 3 were used. In any case, as shown in the schematic diagram of FIG. 4A, the protective metal 14 is selectively deposited on the silver alloy or silver grain boundary portion 52 exposed on the surface of the silver reflecting layer 13, and exposed on the surface. It was confirmed that most of the silver crystal particle part was exposed without being covered with the protective metal 14.

  Using the LED lead frame 10 manufactured in Example 1, Example 2, and Example 3 and the LED lead frame of Comparative Example 1, an optical semiconductor device of the type shown in FIG. 6 was prepared. That is, the epoxy resin reflector 16 and the insulating resin 18 are formed by a transfer molding method, an LED element made of various GaN-based compound semiconductor single crystals such as InGaN is placed on the first lead portion, and the LED element and the second lead After the parts are connected to each other by ball bonding using a gold wire, the sealing resin part 17 is formed of silicone resin, whereby the optical semiconductor device 30 using the LED lead frame 10 described in this example is manufactured. Produced.

  The optical semiconductor device using the LED lead frame 10 manufactured in Example 1, Example 2, and Example 3 is the same as the optical semiconductor device using the LED lead frame manufactured in Comparative Example 1. In comparison, in the manufacturing process, there were few defects in wire bonding, excellent initial luminous efficiency, and excellent performance with little luminance attenuation and little change in emission wavelength even for long-term use.

[Reflectance evaluation test]
In order to evaluate changes in reflectance and copper pile-up while avoiding the influence of parts other than the silver reflective layer 13 (difference in mounting of the LED element 11 and shape error of the reflector 16), a sample for evaluating reflectance Was created and evaluated.

(Sample 1-1: equivalent to Example 1)
A test sample for reflectance measurement, which is a sample for reflectance evaluation, is prepared by preparing a copper plate having a thickness of 0.1 mm, a width of 60 mm and a length of 50 mm corresponding to the base material 12, and performing a degreasing process without etching. Later, copper strike plating (thickness 0.05 μm) was applied as an underlayer, and then silver plating was performed by electroplating to form a silver reflective layer 13 (thickness: 3 μm). For the sample for measuring reflectivity, as a sample 1 corresponding to Example 1, the base material 12 on which the silver reflective layer 13 was formed was reflowed at 400 ° C. for 2 minutes (product name: RN-CS, Panasonic Corporation). Made). Subsequently, the protective metal 14 with a thickness of 10 nm made of tin so that a part of the silver reflective layer 13 is exposed by plating with a flash plating solution of tin on the silver reflective layer 13 formed as described above. Thus, Sample 1-1 corresponding to Example 1 was obtained.

(Sample 2-1 ... equivalent to Example 2)
In Sample 1-1, a bismuth flash plating solution is used instead of the tin flash plating solution, and a part of the silver reflective layer 13 is exposed on the silver reflective layer 13 by plating with the bismuth flash plating solution. A protective metal 14 having a thickness of 10 nm was formed from bismuth to prepare a sample 2-1 corresponding to Example 2.

(Sample 3-1 ... equivalent to Example 3)
In Sample 1-1, an indium flash plating solution is used instead of a tin flash plating solution, and plating is performed on the silver reflective layer 13 with an indium flash plating solution so that a part of the silver reflective layer 13 is exposed. A protective metal 14 having a thickness of 10 nm made of indium was formed on Sample 1, and Sample 3-1 corresponding to Example 3 was obtained.

(Sample 4-1 ... equivalent to Comparative Example 1)
The base material 12 on which the silver reflective layer 13 was formed in Sample 1-1 was heated at 400 ° C. for 2 minutes using a reflow furnace (product name: RN-CS, manufactured by Panasonic Corporation). A comparative sample in which no post-protection metal was formed was prepared as Sample 4-1.

(Evaluation of reflectance)
The initial reflectivity was evaluated as the initial reflectivity, and the reflectivity after sulfidation was measured over time as the reflectivity due to sulfurization. The results are summarized in the test results relating to the reflectivity in Table 1.

The initial reflectance is obtained by measuring the reflectance in the visible light region using a reflective spectrophotometer (UV2550, manufactured by Shimadzu Corporation) immediately after preparing Samples 4-1 to 4-4.
The reflectivity after the sulfidation test was immersed in 0.2% ammonium sulfide solution for 5 minutes immediately after preparing Samples 4-1 to 4-4. The treated sample was measured with a reflection type spectrophotometer (UV2550, manufactured by Shimadzu Corporation).

  Moreover, the evaluation after a pileup test was performed as a coloring guideline by copper pileup (accumulation). The evaluation after the pile-up test was carried out immediately after producing Samples 4-1 to 4-4, after heating using a reflow furnace (product name: RN-CS, manufactured by Panasonic Corporation) at 400 ° C. for 30 minutes. In comparison with the heated sample, the case where coloring was observed was evaluated as x, and the case where coloring was not observed was evaluated as ◯.

  As shown in Table 1, in Sample 1-1, Sample 2-1, and Sample 3-1, which correspond to Example 1, Example 2, and Example 3, the initial reflectance is excellent, and after the sulfurization test It was confirmed that the decrease in the reflectance was significantly suppressed. On the other hand, in Sample 1-4, although the initial reflectivity can be evaluated to be substantially the same as Sample 1-1, Sample 2-1, and Sample 3-1, the reflectivity after the sulfidation test is significantly reduced. It was confirmed that In sample 1-5, the decrease in reflectivity after the sulfidation test was hardly confirmed, but the initial reflectivity may be decreased due to the formation of the indium plating layer on the entire surface of the silver plating layer. confirmed. Thus, like the sample 1-1, the sample 2-1, and the sample 3-1, which correspond to the first example, the second example, and the third example, the silver reflection layer is exposed so that a part of the silver reflection layer is exposed. By providing a protective metal made of a metal having a standard electrode potential lower than that of silver and a Young's modulus lower than that of silver, which partially covers the layer, the reflectance in the initial stage of production is improved, and sulfurization is performed. It is considered that resistance to corrosive gases such as hydrogen can be improved.

  Moreover, as shown in Table 1, in Sample 1-1, Sample 2-1, and Sample 3-1, which correspond to Example 1, Example 2, and Example 3, copper pileup is suppressed. confirmed. In Sample 1-4, the test lead frame protective metal 114 is not formed on the test lead frame silver reflective layer 113, so that the test lead frame silver reflective layer is formed by copper pileup from the base material 12. It is presumed that 113 coloring was observed. In Sample 1-1, Sample 2-1, and Sample 3-1, which correspond to Example 1, Example 2, and Example 3, the test lead frame protective metal 114 on the test lead frame silver reflective layer 113 is used. It is presumed that copper pile-up from the base material 12 was suppressed and the decrease in reflectance could be suppressed.

[Ion migration evaluation test]
In order to evaluate silver ion migration while avoiding the influence of parts other than the silver reflecting layer 13 (difference in mounting the LED element 11 and shape error of the reflector 16), an ion migration evaluation sample was prepared and evaluated.

(Sample 1-2: equivalent to Example 1)
Using a copper plate (thickness: 0.1 mm), an ion migration test lead frame 101 having a comb-shaped electrode having the shape shown in FIG. At this time, the dimensions of the insulating slit 119 and the electrode portion were all 50 μm for W1, W2, and W3. After the copper strike plating was performed on the comb-shaped electrode (a-1) in the same manner as in Example 1, a glossy silver plating layer corresponding to the silver reflection layer 13 was formed as a test lead frame silver reflection layer 113 by electrolytic plating. Then, heat treatment was performed for 2 minutes at 400 ° C. using a hot plate (FIG. 11 (b-1). Next, a tin flash plating solution was used on the test leadframe silver reflective layer 113 in the same manner as in Example 1. A test lead frame protection metal 114 is partially formed of tin (FIG. 11 (c-3)) An epoxy resin is formed by transfer molding so that the surface provided with the test lead frame protection metal 114 is exposed. The test lead frame insulating resin layer 118 (corresponding to the insulating resin 18 of Example 1) was formed (FIG. 12D-1). A lead frame sealing resin portion 117 (corresponding to the sealing resin portion 17) is formed (FIG. 12 (e-1), cut as shown in FIG. 12 (f-1), and an ion migration test piece (comb electrode: L / S = 50 um / 50 um).

(Sample 2-2: equivalent to Example 2)
In Sample 1-2, a bismuth flash plating solution is used instead of a tin flash plating solution, and the test leadframe silver reflective layer 113 is plated with a bismuth flash plating solution to test the leadframe silver reflective layer. A test lead frame protection metal 114 with a film thickness of 10 nm made of bismuth was formed so as to expose a part of 113, and a sample 2-2 corresponding to Example 2 was obtained.

(Sample 3-2 ... equivalent to Example 3)
In Sample 1-2, a test leadframe silver reflective layer was prepared by plating an indium flash plating solution on the test leadframe silver reflective layer 113 using an indium flash plating solution instead of a tin flash plating solution. A test lead frame protection metal 114 with a film thickness of 10 nm was formed of bismuth so as to expose a part of 113, and a sample 3-2 corresponding to Example 2 was obtained.

(Sample 4-2 ... equivalent to Comparative Example 1)
In Sample 1-2, after forming the test leadframe silver reflective layer 113, heat treatment was performed at 400 ° C. for 2 minutes using a hot plate (FIG. 13 (b-1), comparison in which no post-protection metal was formed. A sample was prepared (FIG. 13 (c-1)) and used as sample 4-2.

(Ion migration test)
Immediately after preparing Samples 4-1 to 4-4, the insulation resistance was measured with a measuring device (SIR 13 manufactured by Enomoto Kasei Co., Ltd.) to obtain the initial insulation resistance value. Further, the temperature is 85 ° C. and the humidity is 85% R.D. H. A sample was placed in the tank, and after applying DC12V for 500 hours and 1000 hours, the insulation resistance value was measured and evaluated. The test results regarding the ion migration in Table 2 are described as the evaluation results. In Table 2, “◯” indicates an insulation resistance of 1.0 × 10 ⁸ Ω or more, “Δ” indicates an insulation resistance of 1.0 × 10 ⁴ Ω to 1.0 × 10 ⁶ Ω, and “×” indicates an insulation. It shows that the resistance is 1.0 × 10 ⁴ Ω or less.

  As shown in Table 2, in Sample 1-2, Sample 2-2, and Sample 3-2 corresponding to Example 1, Example 2, and Example 3, a decrease in insulation resistance due to silver ion migration is suppressed. ing. On the other hand, in Sample 4-2, although the initial insulation resistance value can be evaluated to be substantially equivalent to Sample 1-2, Sample 2-2, and Sample 3-2, the insulation resistance after the ion migration test is It was confirmed that the value rose remarkably. Thus, like the sample 1-2, the sample 2-2, and the sample 3-2 corresponding to Example 1, Example 2, and Example 3, the silver reflection is performed so that a part of the silver reflection layer is exposed. Suppressing the decrease in insulation resistance due to ion migration of silver by providing a protective metal made of a metal partially covered with a layer and having a lower standard electrode potential than silver and a lower Young's modulus than silver It is considered possible.

  From these evaluation results, when an optical semiconductor device was fabricated using the LED lead frame 10 in Example 1, Example 2, and Example 3, the reliability due to the decrease in insulation resistance due to ion migration was confirmed. It can be seen that the decrease can be suppressed. At the same time, the reduction of the luminous efficiency of the optical semiconductor device due to the coloring of the silver reflecting surface by hydrogen sulfide in the air, the reduction of wire bonding defects during manufacturing due to the copper pile-up, and the copper It can be seen that there is also an excellent effect in suppressing the decrease in light emission efficiency during long-term use due to the pile-up.

In the manufacture of various optical semiconductor devices using LED elements, the present invention maintains a high initial reflectivity and suppresses coloration due to ion migration, sulfurization and copper pile-up of the silver reflection layer over a long period of time. Thus, the invention is useful for suppressing a decrease in light emission efficiency of the optical semiconductor device.

10: LED lead frame 10a: Lead frame LED mounting surface 11: LED element 12: Base material 13: Silver reflective layer 14: Protective metal (standard electrode potential lower than silver and elastic modulus higher than silver Low metal)
15: bonding wire 16: reflector 17: sealing resin part 18: insulating resin 19: insulating slit 20: groove part 21: first lead part 22: second lead part 23: third lead part 30: optical semiconductor device 41: etching Resist 42: Plating resist 51: Silver alloy or silver crystal particle 52: Exposed silver alloy or silver grain boundary 53: Silver alloy or silver grain boundary 61a: Package connecting part 61b: Package connecting part 61c: Package Connection portion 101: lead frame for inmigration test 113: test lead frame silver reflective layer 114: test lead frame protection metal 117: test lead frame sealing resin portion 118: test lead frame insulating resin 119: test Lead frame insulating slit RA: reflector forming area MA: mounting area PA: package Pass

Claims (3)

  In the manufacture of an LED lead frame for mounting an LED element, a lead frame having a mounting surface on which the LED element of the lead frame is mounted is prepared, and the lead frame mounting surface side includes silver or a silver alloy. A silver reflective layer is provided as a layer, and then a silver grain boundary portion exposed on the surface of the silver reflective layer is exposed by a partially covered portion so that a part of the silver reflective layer is exposed. A method of manufacturing a lead frame, comprising forming a protective material so as to reduce the amount.   2. The lead frame according to claim 1, wherein the silver reflective layer has a grain boundary reduced by heat treatment before the treatment of partially covering the silver reflective layer with the protective material. 3. Manufacturing method. The process of partially covering with the protective substance is characterized in that a protective metal made of a metal having a lower standard electrode potential than silver and a lower Young's modulus than silver is formed by a plating method. A method for manufacturing a lead frame according to claim 1.

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