JP2011151239A - Lead frame for led and method for manufacturing led module - Google Patents

Abstract

Provided is a lead frame suitable for mounting a plurality of LEDs at high density, and having a structure in which a resin can firmly adhere to each other.
A plurality of lead islands, and a plurality of common islands in which a lead island and an LED chip mounting pad corresponding to each lead island are integrated; An LED lead frame comprising: a tie bar that connects adjacent non-corresponding common islands, wherein at least one of the lead island or the common island is connected to a support frame by a suspension bar.
[Selection] Figure 2

Description

  The present invention relates to a structure of a lead frame for mounting a plurality of light emitting diodes in a planar shape, and a method of manufacturing an LED module using the lead frame.

In general, an electronic element such as a semiconductor integrated circuit (LSI, IC) or a light emitting diode (LED) manufactured by a wafer process has a thickness of 1 mm or less and a size of about 1 cm ² or less, and power. In some cases, the number of terminals may be from several tens to several thousand.

  Therefore, these electronic devices have terminals on one surface with the same pitch as the terminals formed on the electronic device, and terminals on the other surface with a pitch expanded to such an extent that it can be easily and firmly connected to an external device. It is mounted on a special board to prepare for use. Electrical connection to the outside is made through terminals having an enlarged pitch formed on the other surface of this special substrate.

  Here, the LED or Si diode as the electronic element according to the present invention is a two-terminal type electronic element having only two terminals to which electric power is applied, and is suitable for LSIs and ICs having hundreds of terminals. In comparison, the number of terminals is small, and if the problem of the size of the substrate on which the electronic element (LED or Si diode) is mounted is not taken into consideration, there is almost no difficulty in forming fine wiring.

  Therefore, as a special substrate on which the two-terminal LED is mounted, a ceramic substrate, a printed circuit board, a lead frame, or the like developed for LSI or IC can be used almost as it is.

  A ceramic substrate has good electrical characteristics, a low coefficient of thermal expansion, and excellent reliability, but has a drawback of high cost. In addition, ceramic has better thermal conductivity than resin but is inferior to metal. Therefore, in order to dissipate the heat generated in the LED, it is necessary to provide a heat sink made of metal with a certain thickness in contact with the LED. Therefore, there is a problem that it is difficult to make it thin and light. When an LED is used as a backlight of a liquid crystal display device, it is a particularly important factor to make it thin and preferably light.

  Moreover, when a printed circuit board is used as a substrate for mounting an electronic element on which a two-terminal LED is mounted, an epoxy resin or a glass epoxy resin that is a base material of the printed circuit board has a higher thermal resistance than a ceramic or a metal. In order to solve this problem, a printed board in which a metal plate such as Cu (copper) or Al (aluminum) is inserted into the inner layer of the board must be employed. In addition, in order to efficiently use the light emitted from the LED as a light source, the light emitted from the LED may be reflected and the reflected light may be used, but in order to ensure high light reflectance, the back of the LED A process of applying a light-reflective ceramic ink to the surface of the substrate is required, and both processes are expensive.

  On the other hand, a lead frame used for mounting an electronic element is not suitable for mounting a multi-terminal electronic element, but is composed of a plate-shaped alloy thin plate such as iron-nickel or an alloy thin plate such as copper-nickel-tin. Since the lead frame metal material can be manufactured by photo-etching using an etchant such as ferric chloride or by punching using a mold, it can be obtained at a very low cost.

As a lead frame for mounting one LED chip, one having a total of three islands is known. Such a lead frame has a pad portion (island portion) as a main surface on which the LED chip is mounted and a pad portion (island portion) that is electrically insulated from each other for electrical connection with the LED chip. ) And three islands including two lead islands that are electrically insulated. Further, a lead frame for mounting one LED chip is also known which has a total of two islands. That is, a total of two islands are provided, one common island in which the pad portion and one of the two lead islands are shared, and one lead island.

FIG. 4 is a cross-sectional view of an example of an LED module 40 using a lead frame having two islands. The pad portion 41a on which the LED chip of the lead frame is mounted has the LED 44 mounted on its main surface side, and its back surface is exposed to the air, so that Joule heat generated from the LED 44 is dissipated. Although not shown, a heat radiating plate for improving the heat radiation efficiency may be attached to the back surface. The LED 44 is connected to a pad portion 41a which is one electrode integrated with the LED chip mounting portion through a conductive material 47 such as silver paste or solder, and the lead island 41b which is the other electrode is a metal wire It is electrically connected at 45.
Further, a bank 43 made of a resin whose inside is inclined forward is formed so as to surround the LED 44, and a sealing resin layer 46 is embedded in the bank so as to cover the LED 44 and the metal wire 45. A reflective film 48 made of a metal film or the like may be formed inside the bank 43. The two islands 41a and 41b are completely separated by a slit 42 so as not to short-circuit, and the slit 42 is filled with an insulating resin 49 for filling.

  As can be easily understood from FIG. 4, the lead frame is composed of islands 41a and 41b made of a plurality of plate-shaped metal pieces insulated from each other when attention is paid only to the metal portion.

  Therefore, when manufacturing a lead frame, the method is to use a support frame via the suspension bar 12 so that the plate-like metal pieces 11 serving as islands are arranged in a certain manner and are not separated from the metal plate used as a material. It is necessary to form the lead frame base material 10 in which the island 14 is fixed to 13 (see FIGS. 1A and 1B). Then, it is necessary to finally cut the suspension bar 12 in order to break the electrical continuity with each other. However, prior to cutting, the island 11 is not separated even if the metal piece 11 is cut off from the unnecessary support frame 13. And the opening 19 other than the part where the support frame 13 is formed are embedded and fixed with resin. Next, the LED chip 16 is fixed to a predetermined position of the lead frame base material, and wiring processing and sealing processing are performed. After that, the suspension bar portion 12 is cut and separated from the support frame 13 to obtain the corresponding LED module, and further, the casing processing that is accommodated in a protective case or the like is performed to finally obtain a plurality of LED modules. . This series of processing is performed simultaneously by applying multiple faces to a single metal substrate or a long metal plate until it is made into individual pieces.

  Patent Document 1 describes a frame pattern of a multiple lead frame for taking a multiple surface of a lead frame substrate on which a single LED chip is mounted from a metal plate. According to this, the number of islands allocated to one LED chip is two as shown in FIG. In other words, the island is composed of two islands, one lead island and one common island corresponding to the lead island, and the islands supported by the support frame are arranged periodically in the vertical and horizontal directions. is there.

  In addition, Patent Documents 2 to 5 below describe a technique for mounting an electronic element such as an LED on a carrier and a heat dissipation technique for preventing heat storage.

Japanese Patent No. 4205135 JP 2003-347600 A JP 2004-172160 A JP 2007-220925 A JP 2003-8071 A

  Needless to say, the LED chip is used alone. In some cases, a plurality of LED chips are arranged in close proximity to each other in order to increase the light emission amount (light emission density) or to adjust the light emission color. In particular, as a backlight for a liquid crystal display device, a light and thin light source including a plurality of LED chips arranged in a plane shape so as to increase the light intensity is particularly required.

  When a plurality of LED chips are densely packed, normally, a plurality of LED modules individually filled with resin and sealed as shown in FIG. 4 or one LED module further subjected to casing processing are arranged vertically and horizontally. Most of them are integrated side by side. The problem in this case is that the number of LED chips that contribute to light emission is small relative to the occupied area of the module, which is bulky but has a low light emission density. In addition, there is a problem that it is difficult to reduce the weight because the thickness is large.

  Furthermore, the lead frame that carries the LED chip embeds the opening other than the island with a filling resin in order to maintain the form as a light emitter, but the contact area between the resin and the metal is small, and the adhesion is low. There is a problem that peeling occurs or long-term reliability is poor. In the first place, there is a problem that the resin filling itself does not go well.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a lead frame base material structure as a cutting unit suitable for mounting a plurality of LED chips. More specifically, a large number of LED chips are mounted per unit area, and a plurality of LED chips are arranged in a plane so that the island metal pieces constituting the lead frame substrate and the filling resin can be more firmly bonded. An object of the present invention is to provide a lead frame base material having a possible structure and to provide a manufacturing method of an LED module for mounting a plurality of LED chips on the lead frame base material.

  In order to achieve the above object, the invention according to claim 1 is a plurality of common islands that are connected to a support frame by a suspension bar and are independent from each other, and are integrated with LED pad mounting pads and lead islands. It is set as the lead frame for LED characterized by providing these.

  The invention according to claim 2 of the present invention includes a plurality of lead islands, and a plurality of common islands in which the LED chip mounting pad portion corresponding to each lead island and the lead island are integrated. , Comprising a tie bar for connecting each lead island and an adjacent non-corresponding common island, wherein at least one of the lead island or the common island is connected to a support frame by a suspension bar It is a lead frame.

Conventionally, two islands are assigned to one LED. However, according to the above-mentioned invention for the purpose of connecting a plurality of LEDs in series, it is substantially one.
This is because the current flows as follows: island 1 → LED 1 mounted on the island 1 → metal wire → island 2 → LED 2 mounted on the island 2 → metal wire.
Furthermore, according to the second aspect, since the separated islands are connected to each other by the tie bar, the stability of the form is enhanced even when the resin is fixed.

  The invention according to claim 3 of the present invention is the LED lead frame according to claim 2, wherein the thickness of the tie bar is smaller than the thickness of the island.

  In this configuration, the thickness of the frame is not set to be the same, and a part of the thickness is reduced. By installing this portion, the in-plane fluidity of the resin is increased and the contact area between the resin and the metal is increased.

  The invention according to claim 4 of the present invention is characterized in that the island is formed by etching from the front and back of a thin metal plate, and the tie bar is formed by half etching. The LED lead frame described in the item.

  The invention according to claim 5 of the present invention is the LED lead frame according to any one of claims 1 to 4, wherein the LED lead frame is multifaceted.

Invention of Claim 6 of this invention is a manufacturing method of the LED module which mounts several LED using the LED lead frame of any one of Claim 1-5, Comprising: At least ,
1. A step of embedding the opening portion of the LED lead frame with a first resin so that the resin is flush with the lead frame, to form a resin / lead frame integrated structure;
2. One island of a plurality of islands connected by a tie bar and one island of a plurality of islands connected by another tie bar adjacent to the island are electrically connected by a metal wire or solder with an LED interposed therebetween. The process of mounting the
3. Forming a reflector with a first resin so as to include all LEDs belonging to the same module inside;
4). Molding the LED and the electrical connection portion with a second resin;
5. Cutting the suspension bar portion into individual LED modules comprising a plurality of LEDs,
It is set as the manufacturing method of the LED module characterized by having.

  The invention according to claim 7 of the present invention is the LED module manufacturing method according to claim 6, wherein the first resin is a highly light-reflective resin.

  According to the present invention, the light extraction efficiency to the front increases.

  The invention according to claim 8 of the present invention is the LED module manufacturing method according to any one of claims 6 to 7, wherein the first resin contains ceramic fine particles. It is.

  According to the present invention, the reflectance of the resin portion is improved, and the light extraction efficiency is improved. In addition, thermal conductivity is increased.

If the lead frame of the present invention is used, a plurality of LED chips can be arranged in a planar shape on the same lead frame. Therefore, on the lead frame as a cutting unit, the frame pattern for the purpose of mounting a plurality of LED chips in series connection,
The number of metal islands required as an electrode is halved compared to the case where a single LED chip is casing and connected in series. As a result, it is possible to select either mounting the LED chips at a high density or increasing the area of the metal frame portion exposed to the air for heat dissipation. Alternatively, both can be juxtaposed at a desired ratio to a certain extent. Further, a control Si diode, which is a two-terminal element other than an LED, can also be mounted on the same lead frame and on the same surface. Therefore, if an LED chip is mounted on the lead frame of the present invention to form a planar light source, it can be used as a backlight for a liquid crystal display device that requires a planar light source.

  In addition, some areas that are necessary for damming the sealing resin for protecting the LED chip and the metal wire and that need to be secured on the lead frame are partially omitted by sharing them. As a result, the lead frame becomes compact, and the finished LED module becomes compact. Naturally, since the number of impositions can be increased, the cost can be reduced.

  Furthermore, since the thickness of the lead frame is changed and the island is fixed with a tie bar, the fluidity of the resin is improved when the frame is embedded in the opening and the frame / resin surface is molded. The uniformity of the resin thickness and the horizontal position of the island are stable. At the same time, since the contact area between the resin and the frame is increased, a durable thin LED module with less peeling can be manufactured. In addition, an LED module with high light extraction efficiency can be obtained by using a resin having a high reflectance for the resin used for embedding.

  The lead frame of the present invention may be planar, but depending on the use purpose of the lead frame, a step or a curve may be provided.

(A)-(d) is a figure explaining the basic composition of the island pattern of the lead frame which becomes this invention, and a figure explaining an electrical connection state. (A)-(c) is a figure explaining an example of the island pattern at the time of correcting the basic island pattern for mounting two LED, and a figure explaining an electrical connection state. It is a partial figure of process drawing explaining the manufacturing method of the LED module which becomes this invention. It is a typical figure explaining the structure of an LED module provided with one LED. It is a figure of the cross-sectional view explaining an example of the resin mold to the lead frame using a metal mold | die. It is a figure which illustrates typically the light reflection function of filling resin.

  The present invention defines an arrangement shape and a cross-sectional shape of an island and a tie bar included in a punched lead frame obtained by cutting a suspension bar portion with a mold, and is particularly suitable for mounting a plurality of LED chips. This is about the basic character of the island pattern.

  Hereinafter, the present invention will be described assuming an embodiment. In this specification, “support frame” and “hanging bar” are defined as follows.

  FIGS. 1A to 1D are views according to a first embodiment of an LED lead frame (hereinafter, the lead frame is referred to as LF), and briefly illustrate the features of the present invention.

FIG. 1B is a top view illustrating the LF substrate 10 including a substantially quadrangular island 11 for mounting four LED chips and two Si diodes. The two islands 15 and 15 'arranged in the vertical direction on the right side in the figure are portions where the Si diode 17 is mounted, but the two islands 15 and 15' may be omitted depending on the specification of the LF. The LED mounting island 11 is connected to the support frame 13 by suspension bars 12 and 12 '. The leftmost island 14 is an electrode island, and the rightmost islands 15 and 15 'are for mounting Si diodes, but also serve as electrodes for external connection. Both are connected to a support frame 13 by a suspension bar 12.

  FIG. 1C is a cross-sectional view taken along line XX ′ in FIG. The wedge shape of the end surface is a schematic and exaggerated illustration of the finished shape when etching is performed so as to be the same depth from the front and back. When punched with a mold, the cross section becomes vertical. If the etching process is performed asymmetrically, the cross section becomes a distorted wedge shape.

FIG. 1D is a schematic diagram showing a state in which an LED 16 and an Si diode 17 are mounted on the island 11 and the island 15 via the conductive material 18 and the island adjacent to each electronic element is connected by the metal wire 21. . The left and right islands 14 and 15 serve as lead terminals connected to the outside. Since this portion may include a portion exposed to the outside, the length is drawn longer in that sense.
The current flows through the right island 15 → Si diode 17 → metal wire 21 → island → LED 16 → metal wire →... → island 14. Either the front or back of the island can be used to connect to the outside. In other words, in this embodiment, four common islands are arranged from the right in the drawing in which the pad portion on which the LED chip is mounted and the lead island are integrated, and the leftmost island is used as the lead island.

  FIG. 1 (a) is a diagram schematically showing a configuration of a multiple lead frame in which an LF substrate (FIG. 1 (b)) as a cutting unit is multifaceted. For multiple lead frames, both long and single wafer formats are processed in batches, for example, for each part surrounded by a broken line in FIG. 1 (a), and finally in FIG. 1 (b). Cutting is performed at the position indicated by the broken line portion 20. In the figure, the number of cutting units is 4 × 6, but is set as appropriate.

  FIG.1 (e) is a circuit diagram which shows the connection state of LED and Si diode.

  Here, the LF base material as a cutting unit is a portion shown in FIG. As will be described later, the outer shape is adjusted while filling the opening portion 19 of the LF base material with a resin, and then an LED chip is mounted on the LF base material 10 for electrical connection. Further, after performing necessary processing, cutting is performed along the broken line 20. As a result, an LED module having four LED chips is obtained. As is apparent from the figure, the number of LED chips mounted is not particularly limited, and the number of islands may be set as appropriate.

  Comparing FIG. 1 and FIG. 4, the LED chip is directly mounted on one LF 10 having a plurality of islands 11 rather than arranging a plurality of LED modules 40 having two islands 41a and 41b. However, since the island 11 is used as an electrode, the number of islands 11 assigned to the LED chip is halved. This is equivalent to a combination of two islands 41a and 41b in FIG. 4, which corresponds to an increase in the heat radiation area. Or, LED chips can be mounted at a higher density.

2A to 2C are diagrams according to the second embodiment. The basic pattern of the square island 11 shown in Fig. 1 is modified to have a constriction at the center so that two LED chips connected in parallel can be mounted on one common island. The island is also constricted in the center. Here, “tie bar 30” is an electrical connection between the common island on which the LED chip corresponding to the lead island (for example, 22b, 22d) is mounted and the other common island (22a, 22c) that does not correspond to self adjacent to the common island. It is a metal part that connects to the island and formed at the same time as the island is formed. In the present embodiment, the tie bar 30 connects the constricted portion of the lead island (for example, 22b, 22d) and the constricted portion of the adjacent common island (22a, 22c) that does not correspond to itself. Therefore, in the present embodiment, the common island, the lead island, and the tie bar 30 form an H-shaped pattern, but the tie bar 30 can take various forms depending on the shape and arrangement of the islands. The square or rectangular shape of the island is merely an example, and other shapes may be used as long as the LED chip can be mounted and a wire bonding pad can be taken.

FIG. 2A is a top view of the lead frame. The positions of the LED chip 16 and the metal wire 21 are indicated by broken lines so that the significance of dividing the island into four can be understood. Two LED chips are connected in parallel, and four sets are arranged in series. A circuit diagram according to this embodiment is shown in FIG. It should be noted that the Si diode is drawn so as to straddle two islands instead of wire bonding connection. Such a connection is also possible.
Further, depending on the specifications of the LF, the island where the Si diode is arranged may or may not be provided.

  The tie bar 30 electrically connects the islands 22 and also functions to connect the plate-like island pieces so that the relative positional relationship can be maintained in the processing step (particularly, molding resin injection) (not to fluff). Is. This is because in particular, if the island is fixed to the island where the wire bonding is planned while being displaced in the horizontal and vertical directions, the wire bonding may be broken.

  Moreover, the recessed parts 23 and 24 of FIG.2 (b) which show the fragmentary sectional view of Fig.2 (a) are equivalent to the tie bar 30, and the thickness of the said part is set thinly compared with the other part. In particular, in the figure, the back surface portion of the tie bar 30 is thinned. In this configuration, when the opening 19 is filled and molded later with a filling resin, the resin is easy to flow, so that the moldability is excellent and the area where the resin and the metal frame are in contact with each other is increased and the durability is increased. This is because it has an increasing effect and is more preferable. The thinned portion is not limited to 30 tie bars, but may be in an island portion, a suspension bar portion, or a support frame. This is determined in consideration of the structure of the resin filling device and the arrangement of islands.

  Next, the manufacturing method of the LED lead frame and LED module according to the present invention will be described.

  First, a sheet metal material made of an alloy thin plate such as iron-nickel or a metal alloy such as copper-nickel-tin is prepared, subjected to a cleaning process such as degreasing, and then a photoresist is applied to the surface of the plate metal material. Is applied and dried to form a photoresist layer.

  Next, in order to form a metal pattern such as an island for mounting an LED or Si diode, a tie bar for connecting the island, a suspension bar for supporting the island, and a support frame, a photoresist layer is formed through a photomask having a predetermined pattern. Next, the photoresist layer is subjected to a development process, and a hardening process is performed as necessary. As a result, a resist pattern is formed at a site corresponding to the aforementioned pattern, and the resist at other sites is removed.

Similarly, a photoresist is applied to the back surface of the plate-shaped metal material to form a photoresist layer. The aforementioned steps such as pattern exposure and development are repeated. Normally, the photoresist pattern on the front and back is plane-symmetrical on the front and back, but when the thickness of the tie bar part is set thin, a part exposed from the photoresist on the surface side of the part using a predetermined photomask It is desirable to use a so-called half-etching method in which the etching proceeds only from the back surface without providing a film. When half etching is performed on the tie bar, it may be performed from either the front side or the back side. However, if half-etching is performed only from the front side and the diver is left on the back side, the tie bar is exposed from the resin on the back side when the resin is sealed with the filling resin, so the heat dissipation surface increases. It can be said that it is preferable that heat dissipation is improved.

  Next, a corrosion-resistant resin film is adhered to the back surface of the plate-shaped metal material, and the photoresist non-formed portion on the surface of the plate-shaped metal material is moved from the surface side to the predetermined depth, usually the center. Etching processing (half etching processing) is performed using an etchant such as iron. Thereafter, washing is performed, and a corrosion-resistant resin film is attached to the surface.

  Next, the corrosion-resistant resin film on the back surface of the plate-shaped metal material is peeled off, and ferric chloride is formed from the back surface side of the plate-shaped metal material to the non-photoresist-formed portion on the back surface to a predetermined depth, usually the center Etching processing is performed using an etchant such as. As a result, a penetrating portion or a half-etched portion is formed in the metal portion where the corresponding resist pattern is not formed on the front surface and the back surface, and becomes an opening portion of the lead frame as viewed from above. This process is performed by multiple imposition, and the LED lead frame 10 as shown in FIGS. 1 and 2 is formed (FIG. 3A).

As described above, the lead frame 10 can be applied by a pressing method using a mold in addition to the photolithography method. However, when the metal frame includes a portion having a different thickness, when the fine pattern is included, the front and back etching depths are different. In such a case, the photolithography method is suitable.
In addition, the process of reducing the thickness as provided in the tie bar part, regardless of the front and back, is a part other than the tie bar, for example, an LED mounting island and does not affect the LED mounting or wire bonding pad. This can also be done in the part or in the support frame.

  Next, using a filling mold as shown in FIG. 5, the mold filling resin 4 is embedded in the opening 19 of the lead frame 10 so as to be substantially flush with the lead frame surface.

  That is, the lead frame 10 is loaded into a recess of the mold 50 in which a recess having a predetermined internal shape for accommodating the lead frame 10 is previously formed. In addition, as shown in FIG. 5, a lead frame 10 (multi-sided lead frame) that communicates with a plate-shaped upper mold 50a serving as a lid and an injection port 52 for injecting molten filler resin 4 is loaded. The lower mold 50b is formed with a lower mold 50b in which a possible recess 53 is formed as an internal space. After the lead frame 10 (multi-sided lead frame) is loaded into the recess 53 of the lower mold 50b, the upper mold 50a is used as the lower mold. Generally, 50b is covered and clamped.

  Next, the filling resin 4 heated and melted is injected into the recess 53 (internal space) from the injection port 52, and the opening portion of the loaded lead frame 10 (multi-sided lead frame) is filled with the filling resin 4 and molded. Thus obtained LED lead frame is obtained. After molding, it is cooled and the upper mold is removed, and the lead frame is taken out from the lower mold. As a result, the mounting island, the suspension bar, the front and back surfaces of the support frame, and one side of the tie bar are exposed to the air, the opening is filled with resin, and the other side of the tie bar is covered with the filled resin. A flat LED chip mounting lead frame is formed (FIG. 3B).

  In addition, when filling the filling resin into the LF in the mold, the thickness of the diver 30 is reduced, so that the flow of the filling resin is not hindered by the 30 parts of the diver, and the resin spreads over the entire area of the recess and fills. Air bubbles can be prevented from occurring in the resin.

  According to the present invention, since the lead island and the common island are connected by the tie bar, the number of suspension bars connecting each island to the support frame can be thinned out and reduced. For example, in the example of FIG. 2, each island is not connected to the support frame by the suspension bar, but every other island is connected to the suspension bar support frame. In other words, it is not necessary to connect all of the lead island and the common island to the support frame with a suspension bar, and the number of suspension bars can be reduced, so that the number of suspension bars that hinder the flow of the resin when filling with the filled resin is reduced. This makes it possible to smoothly flow the resin in the mold and prevent bubbles from forming in the filled resin.

  When the filling resin is molded in a molten state and after the molding, the filling resin 4 is held by the stepped portion 32 of the tie bar or the tapered portion 33 of the island, and thereby the filling resin 4 and The contact area with the lead frame 10 is increased. For this reason, the filling resin 4 and the lead frame 10 are firmly in close contact with each other, and the dropping of the lead frame from the filling resin or the dropping of the filling resin from the lead frame can be prevented.

  The suspension bar 12 shown in FIG. 1 and FIG. 2 has the island 11 for a necessary period in order to prevent the island portion 11 and the terminal portions 14 and 15 from falling off the support frame 13 after the etching process. It is formed to keep the metal piece separated without the suspension bar 12 connected to the support frame 13 by cutting the suspension bar 12 and removing the lead frame from the support frame. A lead frame is obtained. In the side sectional view, illustration of the suspension bar portion 12 is omitted. The cutting time of the suspension bar portion 12 may be after the LED chip is mounted or after resin molding, but may be set as appropriate. Further, in the above description, the etching process is performed once for each of the front and back surfaces, a total of two times. However, even if the metal material is etched by one etching performed simultaneously from the front and back surfaces, I do not care.

  Next, after covering the back surface with a protective film (not shown), a silver plating process is performed on a predetermined part of the island in order to improve the connectivity when the LED chip 16 and the adjacent island 11 are electrically connected. A silver plating layer 34 is formed (FIG. 3C).

  Next, a solder paste 35 for electrically connecting the LED chip terminal and the island is applied to a predetermined position of the island by screen printing (FIG. 3D).

  Thereafter, the LED 16 and the Si diode 17 are mounted at predetermined positions, and after passing through the reflow furnace as they are, when cooled, one electrode of the electronic element is bonded and fixed to the island via the solder 35. Next, the terminal on the electronic element and the silver-plated portion of the island are connected by the metal wire 21 by wire bonding (FIG. 3E).

  The plating on the wire bonding area may be gold plating or palladium plating instead of silver plating. Further, prior to performing silver plating, gold plating, or palladium plating on the surface of the electrical connection area, a base plating such as Ni (nickel) plating having excellent heat resistance diffusibility may be performed. Furthermore, it is also possible to perform base plating such as silver plating, gold plating, palladium plating, or Ni (nickel) plating on the back side of the island for heat dissipation. This is because it can also be used for electrical connection with the outside.

  Next, a transparent resin 5 for sealing is applied in a layer form, and prior to this, a bank 43 is formed using, for example, a dispenser so as to surround the LED chip. However, the bank 43 is not necessarily essential.

  Next, a transparent resin 5 is applied on the upper surface side of the island from the LED mounting surface by dispenser discharge or screen printing or the like, and the LED chip 16 and the metal wire 21 are covered in a layered manner with the transparent resin 5 (see FIG. 3 (f)). In this embodiment, the transparent resin 5 has a layered shape, but may have a hemispherical dome shape.

  In the LED module of the present invention, the LED chip 16 emits light in a state where it is embedded in the transparent resin layer 5, so that a high optical gain is obtained when the light emitted from the LED chip 16 is emitted from the transparent resin 5 to the outside. It is important to have sex. For this purpose, for example, a resin having good transparency such as an acrylic resin (polymethamethyl acrylate resin) having light transmittance is selected, but the present inventor in particular, as the filling resin 4, It is desirable to use a resin having high reflectivity at the boundary surface between the filling resin 4 and the transparent resin 5.

  It is desirable that the filling resin 4 has a high reflectance so that light emitted from the LED chip is reflected on the surface of the filling resin and can be emitted to the outside, but in addition, heat resistance, light resistance, thermal conductivity, high It is also desirable to have light diffusibility. Therefore, as the filling resin 4, for example, epoxy resin, modified epoxy resin, silicone resin, acrylic resin, polycarbonate resin, aromatic polyester resin (unsaturated polyester resin), polyphthalamide (PPA), liquid crystal polymer (LCP) Organic polymer materials such as these are desirable, and one type of resin or a mixed resin of a plurality of types of resins may be used.

In order to obtain a high reflectance at the boundary surface between the filling resin 4 and the transparent resin 5, the relationship between the light refractive index n1 of the filling resin 4 and the light refractive index n2 of the transparent resin 5 is set to n1> n2. It is appropriate, and the higher the difference in refractive index, the higher the reflection. However, the refractive index of the resin is approximately 2 or less, and there is a limit in increasing the refractive index difference only with the resin. Therefore, in the present invention, as the filling resin 4, a light diffusing resin in which an additive such as a powdery substance or a granular substance is mixed with a resin mainly composed of the above-mentioned one kind of resin or a mixed resin of plural kinds of resins. Suggest to use. In such a filling resin, since the refractive index n can be 2 or more, high reflectivity at the boundary surface between the filling resin 4 and the transparent resin 5 can be obtained. Examples of the additive to be added to the filling resin 4 include fine particles such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , zirconium oxide, ceramic material, or a mixture thereof. The ratio can be set appropriately in the present invention. For example, it is 1% to 20% or more.

  Below, the effect by giving reflectivity to filling resin is demonstrated. As shown in FIG. 6, the light L emitted from the LED chip 16 travels through the transparent resin 5 and is emitted to the outside. However, a part of the light emitted from the LED chip 16 is reflected at the boundary of the transparent resin 5 in contact with the outside (air) (reflected light M (total reflection light, semi-reflection light, etc. in FIG. 6)). When the filling resin has a high reflectance, the reflected light M reflected at the boundary of the transparent resin 5 (total reflection light or semi-reflection light at the interface between the air and the transparent resin 5) reaches the surface of the filling resin. In this case, the reflected light can be reflected again, and the re-reflected light N re-reflected on the surface of the filling resin can be emitted from the LED chip. On the other hand, when the filling resin does not have reflectivity, the reflected light M enters the filling resin as it is, and is not emitted from the LED chip.

  In this way, by giving the filling resin a high reflectance, it is possible to efficiently extract the light emitted from the LED chip 16 to the outside.

  In addition, when metal plating is performed on the LED chip mounting surface and the electrical connection area, the reflected light M can be converted to re-reflected light N on the plated surface, so that the light emitted from the LED chip 16 can be efficiently used. It is preferable to use.

Furthermore, it can be said that it is preferable to coat the surface of the filled resin with a ceramic ink having an excellent light reflectivity in order to efficiently use the light emitted from the LED chip 16.

  In the lead frame 10 that enables such a structure, the taper of the upper half taper portion is, for example, a C shape, and the taper of the lower half taper portion is, for example, an inverted C shape, The taper directions of the lower structure portions are opposite to each other. Therefore, for example, the filling resin in the part sandwiched between the islands has a constricted part between the upper surface (the surface on the upper structure part side) and the lower surface (the surface on the lower structure part side). To have. Since the lead frame 10 holds the filling resin on the side surfaces that are tapered in the opposite direction above and below the constricted portion, it is possible to prevent the lead frame from dropping off from the filling resin.

2, LED mounting island 4, mold filling resin 5, transparent resin 10, lead frame (base material)
11, LED mounting island 12, suspension bar 13, support frame 14, island 15 as an electrode, Si diode mounting island 16, LED
17, Si diode 18, conductive material 19, lead frame opening 20, cutting line 21, metal wire 22, islands 23 and 24, recessed portion 30, tie bar 32, stepped portion (concave portion) of tie bar
33, taper portion 34 of island, silver plating layer 35, solder paste 41a, 41b, island or pad 42, slit 43, bank 44, LED
45, metal wire 46, sealing resin layer 47, conductive material 48, reflective film 49, insulating resin 50 for mold, mold L, LED emission light M, reflected light N, re-reflected light Z, 1 unit frame

Claims (8)

  An LED lead frame comprising a plurality of common islands that are connected to a support frame by a suspension bar and are independent of each other, each of which is a pad part for mounting an LED chip and a lead island.   It has a plurality of lead islands and a plurality of common islands in which the LED chip mounting pads corresponding to the lead islands and the lead islands are integrated, and the lead islands are adjacent to each other and do not correspond to each other. A lead frame for an LED comprising: a tie bar for connecting to a common island, wherein at least one of the lead island or the common island is connected to a support frame by a suspension bar.   3. The LED lead frame according to claim 2, wherein a thickness of the tie bar is smaller than a thickness of the island.   The LED lead frame according to any one of claims 1 to 3, wherein the islands are formed by etching from the front and back sides of the metal thin plate, and the tie bars are formed by half etching.   The LED lead frame according to any one of claims 1 to 4, wherein the LED lead frame is multifaceted. A method for manufacturing an LED module on which a plurality of LEDs are mounted using the LED lead frame according to any one of claims 1 to 5, comprising at least:
1. A step of embedding the opening portion of the LED lead frame with a first resin so that the resin is flush with the lead frame, to form a resin / lead frame integrated structure;
2. One island of a plurality of islands connected by a tie bar and one island of a plurality of islands connected by another tie bar adjacent to the island are electrically connected by a metal wire or solder with an LED interposed therebetween. The process of mounting the
3. Forming a reflector with a first resin so as to include all LEDs belonging to the same module inside;
4). Molding the LED and the electrical connection portion with a second resin;
5. Cutting the suspension bar portion into individual LED modules comprising a plurality of LEDs,
The manufacturing method of the LED module characterized by having these.   The method of manufacturing an LED module according to claim 6, wherein the first resin is a highly light reflecting resin.   The method for manufacturing an LED module according to claim 6, wherein the first resin contains ceramic fine particles.

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