Method for producing a carrier and method for producing an optoelectronic component

Abstract

Method for producing a carrier (500) for an optoelectronic component (10) comprising the following steps: - Providing a lead frame (100) having a top side (101) and a bottom side (102); - Arranging a first film (200) on the underside (102) of the lead frame (100); - Arranging a second foil (300) on the top side (101) of the lead frame (100); - forming a molded body (400) from a molding material, wherein the lead frame (100) is embedded in the molded body (400); - Remove the first film (200) and the second film (300).

Description

[0001] The present invention relates to a method for producing a carrier for an optoelectronic component according to claim 1 and to a method for producing an optoelectronic component according to claim 8.

[0002] This patent application claims priority from German patent application DE 10 2014 116 370 A1, the disclosure of which is hereby incorporated by reference.

[0003] Optoelectronic components, such as light-emitting diodes, with leadframe-based packages are known from the prior art. To manufacture such optoelectronic components, a leadframe is embedded in a molded body. This typically results in undesired coverage of the leadframe's contact surfaces by the molded body's molding material, which requires subsequent cleaning.

[0004] DE 10 2013 203 350 A1 describes a method for producing an electronic component with steps for arranging an electrically conductive structure on a carrier, for forming a molded body with a first surface and a second surface above the carrier, wherein the electrically conductive structure and an electronic semiconductor chip with a top side and a bottom side are embedded in the molded body in such a way that a surface of the electrically conductive structure is flush with the first surface of the molded body, for creating an opening which extends through the molded body between the second surface of the molded body and a first section of the electrically conductive structure, and for arranging an electrically conductive material in the opening.

[0005] DE 10 2010 025 319 A1 describes a method for producing a surface-mountable semiconductor component with steps for providing an auxiliary carrier which is formed with a plastic material, for applying at least one insert part and at least one optoelectronic component to a mounting surface of the auxiliary carrier, for encasing the optoelectronic component and the insert part with a common molded body, wherein the molded body covers the optoelectronic component and the insert part at least in places with molding fluid, the optoelectronic component and the insert part are not in direct contact with one another, and the optoelectronic component and the insert part are mechanically connected to one another by the molded body, for removing the auxiliary carrier, and for producing individual surface-mountable semiconductor components by severing the molded body.

[0006] One object of the present invention is to provide a method for producing a carrier for an optoelectronic component. This object is achieved by a method having the features of claim 1. A further object of the present invention is to provide a method for producing an optoelectronic component. This object is achieved by a method having the features of claim 8. Various developments are specified in the dependent claims.

[0007] A method for producing a carrier for an optoelectronic component comprises steps of providing a lead frame having a top side and a bottom side, arranging a first film on the bottom side of the lead frame, arranging a second film on the top side of the lead frame, forming a molded body from a molding material, wherein the lead frame is embedded in the molded body, and removing the first film and the second film.

[0008] The films arranged on the underside and on the top side of the lead frame in this process can largely prevent the underside and top side of the lead frame from being covered by the molding material during formation of the molded body. As a result, this process advantageously eliminates the need for a subsequent cleaning step to remove the molding material from the underside and / or top side of the lead frame. This has the advantage that the mechanical and / or chemical stress on the carrier associated with cleaning the top side and / or underside of the carrier is eliminated. This reduces the risk of cracking or other damage to the carrier. This can increase the stability of the carrier obtainable by the process.

[0009] Eliminating the cleaning step also eliminates the risk of roughening the top and / or bottom of the lead frame, which would reduce reflectivity. This allows the carrier obtained by the process to exhibit high optical reflectivity. This allows an optoelectronic component manufactured from the carrier to exhibit increased brightness.

[0010] Furthermore, eliminating the cleaning step reduces the risk of damage to the mold material surrounding the leadframe. Such damage can be associated with accelerated aging, reduced reflectivity, and reduced mechanical stability.

[0011] By eliminating a cleaning step following the formation of the molded body, the risk of scratches or other mechanical damage to the solder contact surfaces of the carrier is also reduced. This can increase the reliability of an optoelectronic component manufactured from the carrier.

[0012] Furthermore, by eliminating a cleaning step to remove mold material covering the bottom and / or top of the lead frame, the time required to perform the process and the cost of the process can be advantageously reduced.

[0013] In one embodiment of the method, the first film and / or the second film are self-adhesive films. Self-adhesive sides of the films can face the underside and / or the top side of the lead frame. Advantageously, the films thereby adhere to the underside and / or the top side of the lead frame, thereby achieving particularly reliable protection of the underside and / or the top side of the lead frame from being covered by the molding material of the molded body. Adhesively attaching the first film and / or the second film to the lead frame also makes the lead frame, with the films adhering to it, particularly easy to handle, thereby making the method particularly simple to carry out.

[0014] In one embodiment of the method, the first film and / or the second film comprise a polyimide, ETFE, or PET. Experience has shown that such films are advantageously suitable for use in molding processes.

[0015] In one embodiment of the method, the molded body is formed by means of a molding process, in particular by means of injection molding. This advantageously enables a cost-effective and reproducible implementation of the manufacturing process.

[0016] In one embodiment of the method, the first foil or the second foil is arranged such that a portion of the underside or the top side of the leadframe remains uncovered by the foil. The molding material is fed between the first foil and the second foil at the uncovered portion. This advantageously ensures reliable embedding of the entire leadframe in the molded body formed from the molding material.

[0017] In one embodiment of the method, the molding material comprises an epoxy resin and / or a silicone. Advantageously, the molding material thus exhibits favorable mechanical properties and is available at low cost.

[0018] In one embodiment of the method, the leadframe comprises a plurality of first leadframe sections and a plurality of second leadframe sections. This makes it possible to produce a plurality of carriers for optoelectronic components from the leadframe. The method thus enables cost-effective mass production.

[0019] A method for producing an optoelectronic component comprises steps for producing a carrier according to a method of the aforementioned type and for arranging an optoelectronic semiconductor chip on a top side of the carrier. This method enables the production of an optoelectronic component with compact external dimensions. The method is suitable for mass production, thereby advantageously reducing the costs for producing an individual optoelectronic component. The carrier of the optoelectronic component obtained by the method, produced according to the aforementioned method, advantageously has a high mechanical quality.

[0020] In one embodiment of the method, the optoelectronic semiconductor chip is electrically conductively connected to a first leadframe section and to a second leadframe section. In the optoelectronic component obtainable by the method, the first leadframe section and the second leadframe section can thus serve to apply electrical voltage and electrical current to the optoelectronic semiconductor chip of the optoelectronic component. At the same time, in the optoelectronic component obtainable by the method, the first leadframe section and the second leadframe section can serve as electrical contact surfaces for electrically contacting the optoelectronic component.

[0021] In one embodiment of the method, the optoelectronic semiconductor chip is arranged on a first leadframe section. The arrangement of the optoelectronic semiconductor chip on the first leadframe section advantageously allows an electrically conductive connection to be established between the optoelectronic semiconductor chip and the first leadframe section at the same time. This advantageously results in a particularly compact design of the optoelectronic component obtainable by the method.

[0022] In one embodiment of the method, this comprises a further step of dividing the molded body such that a molded body section is formed into which one of the first leadframe sections and one of the second leadframe sections are embedded. The optoelectronic semiconductor chip is arranged on the molded body section. The method thus enables the simultaneous production of a plurality of optoelectronic components in common processing steps. This advantageously reduces the costs and time required for the production of an optoelectronic component.

[0023] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments, which are explained in more detail in connection with the drawings. In each case, in a schematic representation Fig. 1 a perspective view of a ladder frame; Fig. 2 a view of the lead frame with a first foil arranged on a bottom side; Fig. 3 the lead frame with a second foil arranged on an upper side; Fig. 4 a molded body formed between the foils, in which the lead frame is embedded; Fig. 5 a perspective view of the molded body after removal of the foils; and Fig. 6 a perspective view of an optoelectronic component produced from a molded body portion of the molded body.

[0024] Fig. 1 shows a schematic perspective view of a lead frame 100.

[0025] The leadframe 100 can also be referred to as a leadframe. The leadframe 100 comprises an electrically conductive material, for example, a metal. The leadframe 100 preferably comprises copper. A coating can be arranged on the surfaces of the leadframe 100 to improve the solderability of the leadframe 100.

[0026] The lead frame 100 has a substantially flat and planar shape with a top side 101 and a bottom side 102 opposite the top side 101. The lead frame 100 can be made, for example, from a sheet metal.

[0027] The leadframe 100 has openings extending from the top side 101 to the bottom side 102 through the leadframe 100, through which the leadframe 100 is divided into a plurality of first leadframe sections 110 and second leadframe sections 120. The openings can be created, for example, using an etching process. In addition to the openings, the leadframe 100 can have further recesses on its top side 101 and / or on its bottom side 102, which do not extend completely through the leadframe 100.

[0028] The first leadframe sections 110 and the second leadframe sections 120 are arranged in a regular grid arrangement in the plane of the leadframe 110. Each first leadframe section 110 and an adjacent second leadframe section 120 form a mating pair. In each such pair, the first leadframe section 110 and the associated second leadframe section 120 are not directly connected to each other, but only via their respective other neighbors.

[0029] Fig. 2 shows a schematic perspective view of the lead frame 100 in one of the representations of the Fig. 1 subsequent processing status.

[0030] A first foil 200 has been arranged on the underside 102 of the leadframe 100. The foil 200 has a first side 201 and a second side 202 opposite the first side 201. The first side 201 of the first foil 200 faces the underside 102 of the leadframe 100 and preferably completely covers the underside 102 of the leadframe 100. If the underside 102 of the leadframe 100 has raised and recessed sections, the first foil 200 is in contact only with the raised sections of the underside 102.

[0031] The first film 200 may, for example, comprise a polyimide.

[0032] The first film 200 can be designed as a self-adhesive film. In this case, the first side 201 of the first film 200 facing the underside 102 of the lead frame 100 is designed to be self-adhesive. The first side 201 of the first film 200 then adheres to the underside 102 of the lead frame 100.

[0033] If the first film 200 is not designed as a self-adhesive film, the first film 200 is preferably designed to be soft and flexible, so that by pressing the lead frame 100 onto the first side 201 of the film 200, a reliable covering of the entire underside 102 of the lead frame 100 by the first film 200 can be ensured.

[0034] Fig. 3 shows a schematic perspective view of the lead frame 100 in one of the representations of the Fig. 2 subsequent processing status.

[0035] A second film 300 has been arranged on the top side 101 of the lead frame 100. The second film 300 has a first side 301 and a second side 302 opposite the first side 301. The first side 301 of the second film 300 faces the top side 101 of the lead frame 100. The second film 300 covers a large part of the top side 101 of the lead frame 100. If the top side 101 of the lead frame 100 has raised and recessed sections, the second film 300 covers only the raised sections of the top side 101 of the lead frame 100.

[0036] The second film 300 preferably covers the top side 101 of the lead frame 100 in all sections except for an uncovered section 310, which remains uncovered by the second film 300. The uncovered section 310 is preferably arranged in an edge region of the lead frame 100. For example, the uncovered section 310 can extend along an edge of the lead frame 100. The uncovered section 310 can also be arranged in a corner region of the lead frame 100.

[0037] The second film 300 can be configured like the first film 200. The second film 300 can, for example, comprise a polyimide.

[0038] The second film 300 can be configured as a self-adhesive film. In this case, the first side 301 of the second film 300 facing the top side 101 of the lead frame 100 is configured to be self-adhesive. In this case, the self-adhesive first side 301 of the second film 300 adheres to the top side 101 of the lead frame 100, thereby reliably covering the top side 101 of the lead frame 100 by the second film 300.

[0039] If the second film 300 is not designed as a self-adhesive film, the second film 300 is preferably designed to be compliant and flexible, so that by pressing the lead frame 100 against the first side 301 of the second film 300, a reliable covering of the entire upper side 101 of the lead frame 100 by the second film 300 can be achieved, except in the uncovered section 310 of the upper side 101 of the lead frame 100.

[0040] As an alternative to the described procedure, it is possible to provide the uncovered portion 310 not on the top side 301 of the lead frame 100, but on the bottom side 102 of the lead frame 100. In this case, the first foil 200 is arranged on the bottom side 102 of the lead frame 100 such that it covers all raised portions of the bottom side 102 of the lead frame 100, except for the uncovered portion 310. The second foil 300 is arranged on the top side 101 of the lead frame 100 such that it covers all raised portions of the top side 101 of the lead frame 100.

[0041] It is also possible to omit the uncovered portion 310. In this case, the two foils 200, 300 cover all raised portions of the top side 101 and the bottom side 102 of the lead frame 100.

[0042] Of course, the second foil 300 can optionally be arranged on the lead frame 100 before the first foil 200.

[0043] Fig. 4 shows a schematic representation of the lead frame 100 arranged between the foils 200, 300 in one of the representations of the Fig. 3 subsequent processing status.

[0044] A molded body 400 has been formed between the first film 200 and the second film 300. The leadframe 100 has been embedded in the molded body 400. The molded body 400 is made of an electrically insulating molding material. The molding material can comprise, for example, an epoxy resin and / or a silicone. The molded body 400 has been formed by a molding process, for example, by transfer molding. The molding material has been introduced via the uncovered section 310 into the area between the first film 200 and the second film 300. Alternatively, the molding material can have been introduced from a side flank of the leadframe 100 into the area between the first film 200 and the second film 300.

[0045] The molded body 400 has been formed with an upper side 401 and a lower side 402 opposite the upper side 401. The upper side 401 of the molded body 400 has been formed adjacent to the first side 301 of the second film 300. The lower side 402 of the molded body 400 has been formed adjacent to the first side 201 of the first film 200.

[0046] The top side 101 of the lead frame 100, protected by the second film 300, and the bottom side 102 of the lead frame 100, protected by the first film 200, were essentially not covered by the material of the molded body 400 during the formation of the molded body 400. As a result, the top side 101 of the lead frame 100 is exposed at the top side 401 of the molded body 400 and is essentially flush with the top side 401 of the molded body 400. Accordingly, the bottom side 102 of the lead frame 100 is exposed at the bottom side 402 of the molded body 400 and is essentially flush with the bottom side 402 of the molded body 400.

[0047] Fig. 5 shows a schematic perspective view of the molded body 400 in one of the representations of the Fig. 4 subsequent processing status.

[0048] The first film 200 has been detached from the underside 402 of the molded body 400. Furthermore, the second film 300 has been detached from the top side 401 of the molded body 400. The detachment of the first film 200 and the second film 300 from the molded body 400 can be achieved, for example, by mechanically peeling off the films 200, 300.

[0049] The molded body 400 with the leadframe 100 embedded in the molded body 400 comprises a plurality of molded body sections 410 that are integrally connected to one another. A first leadframe section 110 and an associated second leadframe section 120 of the leadframe 100 are embedded in each molded body section 410 of the molded body 400. The individual molded body sections 410 can be separated by dividing the molded body 400 and the leadframe 100 embedded in the molded body 400. Dividing the molded body 400 and the leadframe 100 embedded in the molded body 400 can be carried out, for example, by means of a sawing process.

[0050] Fig. 6 shows a schematic perspective view of an optoelectronic component 10.

[0051] The optoelectronic component 10 comprises a separated molded body section 410 of the molded body 400 of the Fig. 5, which forms a carrier 500 of the optoelectronic component 10. The upper side 401 of the molded body section 410 forms a top side 501 of the carrier. The lower side 402 of the molded body section 410 forms a bottom side 502 of the carrier 500.

[0052] One of the first leadframe sections 110 and one of the second leadframe sections 120 of the leadframe 100 is embedded in the molded body section 410 forming the carrier 500. The first leadframe section 110 embedded in the molded body section 410 forming the carrier 500 is electrically insulated from the second leadframe section 120 embedded in the molded body section 410. The first leadframe section 110 and the second leadframe section 120 are accessible from both the top side 501 and the bottom side 502 of the carrier 500.

[0053] An optoelectronic semiconductor chip 600 is arranged on the top side 501 of the carrier 500 of the optoelectronic component 10. The optoelectronic semiconductor chip 600 can be, for example, a light-emitting diode (LED) chip. The optoelectronic semiconductor chip 600 has a top side 601 and a bottom side 602 opposite the top side 601. The optoelectronic semiconductor chip 600 is arranged on the top side 501 of the carrier 500 such that the bottom side 602 of the optoelectronic semiconductor chip 600 faces the top side 501 of the carrier 500. The optoelectronic semiconductor chip 600 can be attached to the top side 501 of the carrier 500, for example, by means of a soldered connection or an adhesive connection.

[0054] The optoelectronic semiconductor chip 600 is electrically conductively connected to the first leadframe section 110 and to the second leadframe section 120 of the carrier 500 of the optoelectronic component 10. In Fig. In the example illustrated in Figure 6, the optoelectronic semiconductor chip 600 is arranged on the first leadframe section 110, whereby an electrically conductive connection exists between an electrical contact of the optoelectronic semiconductor chip 600 arranged on the underside 602 of the optoelectronic semiconductor chip 600 and the first leadframe section 110 of the carrier 500. A second electrical contact of the optoelectronic semiconductor chip 600 arranged on the top side 601 of the optoelectronic semiconductor chip 600 is electrically conductively connected to the second leadframe section 120 by means of a bonding wire 610.

[0055] However, it is also possible, for example, to establish the electrically conductive connection between the optoelectronic semiconductor chip 600 and the first leadframe section 110 using a bonding wire. In this case, both electrical contacts of the optoelectronic semiconductor chip 600 can be arranged on its upper side 601.

[0056] It is also possible to provide both electrical contacts of the optoelectronic semiconductor chip 600 on its underside 602 and to arrange the optoelectronic semiconductor chip 600 in a bridge-like manner on the first lead frame section 110 and the second lead frame section 120 of the carrier 500 such that electrically conductive connections exist between the electrical contacts of the optoelectronic semiconductor chip 600 and the lead frame sections 110, 120 of the carrier 500.

[0057] The arrangement of the optoelectronic semiconductor chip 600 on the upper side 501 of the carrier 500 formed by the molded body section 410 of the molded body 400 preferably takes place before the molded body 400 is divided into the individual molded body sections 410. In this case, an optoelectronic semiconductor chip 600 is arranged on each molded body section 410 of the molded body 400 and is electrically conductively connected to the first leadframe section 110 and the second leadframe section 120 of the respective molded body section 410. Only then is the molded body 400 divided into the individual molded body sections 410. As a result, a plurality of optoelectronic components 10 are formed simultaneously. Alternatively, it is also possible to arrange the optoelectronic semiconductor chip 600 on the upper side 501 of the carrier 500 formed by a molded body section 410 only after the molded body 400 has been divided.

[0058] The sections of the first leadframe section 110 and the second leadframe section 120 exposed on the underside 502 of the carrier 500 of the optoelectronic component 10 can form electrical contact surfaces of the optoelectronic component 10 and serve to electrically contact the optoelectronic component 10. The optoelectronic component 10 can be provided, for example, as an SMT component for surface mounting, for example for surface mounting by reflow soldering.

Claims

[1] Method for producing a carrier (500) for an optoelectronic component (10) comprising the following steps: - Providing a lead frame (100) having a top side (101) and a bottom side (102); - Arranging a first film (200) on the underside (102) of the lead frame (100); - Arranging a second foil (300) on the top side (101) of the lead frame (100); - forming a molded body (400) from a molding material, wherein the lead frame (100) is embedded in the molded body (400); - Remove the first film (200) and the second film (300). [2] Method according to claim 1, wherein the first film (200) and / or the second film (300) are self-adhesive films. [3] Method according to one of the preceding claims, wherein the first film (200) and / or the second film (300) comprise a polyimide, ETFE or PET. [4] Method according to one of the preceding claims, wherein the shaped body (400) is formed by means of a molding process, in particular by means of injection molding. [5] Method according to one of the preceding claims, wherein the first film (200) or the second film (300) is arranged such that a portion (310) of the bottom (102) or the top (101) of the lead frame (100) remains uncovered by the film (200, 300), the molding material being fed between the first film (200) and the second film (300) at the uncovered portion (310). [6] Method according to one of the preceding claims, wherein the molding material comprises an epoxy resin and / or a silicone. [7] Method according to one of the preceding claims, wherein the lead frame (100) comprises a plurality of first lead frame sections (110) and a plurality of second lead frame sections (120). [8] Method for producing an optoelectronic component (10) comprising the following steps: - producing a carrier (500) according to a method according to one of the preceding claims; - Arranging an optoelectronic semiconductor chip (600) on a top side (501) of the carrier (500). [9] Method according to claim 8, wherein the carrier (500) is formed by a method according to claim 7, wherein the optoelectronic semiconductor chip (600) is electrically conductively connected to a first leadframe section (110) and to a second leadframe section (120). [10] The method according to claim 9, wherein the optoelectronic semiconductor chip (600) is arranged on a first leadframe section (110). [11] A method according to any one of claims 9 and 10, wherein the method comprises the following further step: - Dividing the molded body (400) such that a molded body section (410) is formed, into which one of the first leadframe sections (110) and one of the second leadframe sections (120) are embedded, wherein the optoelectronic semiconductor chip (600) is arranged on the molded body section (410).

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