KR20130099177A - Housing and method for producing a housing for an optoelectronic component - Google Patents

Abstract

A housing 1 for a photoelectric element 10 is disclosed. Such a housing 1 comprises an assembly surface, a first connecting lead 31, a second connecting lead 32, and a housing body 2 provided for assembly of the housing. The housing body 2 comprises a connecting area 21 and a surface area 22. The connection region mechanically interconnects the first connection lead and the second connection lead. The surface area at least partially covers the connection area on the side facing away from the assembly surface. The material of the connection area and the material of the surface area are different. Also disclosed is a method of manufacturing the housing 1.

Description

HOUSING AND METHOD FOR PRODUCING A HOUSING FOR AN OPTOELECTRONIC COMPONENT}

The present invention relates to a housing for an optoelectronic device, a method of manufacturing a housing for an optoelectronic device, and an optoelectronic device comprising such a housing.

This patent application claims the priority of German patent application 10 2010 054 591.0, the disclosure of which is hereby incorporated by reference.

In order to fabricate photovoltaic devices based on radiation emitting semiconductor chips, ceramic housings are often used, especially for devices with relatively high output power, because such housings have high aging stability and good heat dissipation characteristics. This is because it is characterized. However, the manufacture of such housings is relatively complex and cost intensive. Often, it is not easy to manufacture inexpensive plastic housings because many plastics have insufficient aging stability, for example, due to degradation due to ultraviolet radiation generated in semiconductor chips. In addition, plastics often have a relatively poor adhesion to the lead frame.

An object of the present invention is to provide a housing which can be manufactured simply and inexpensively while having high mechanical stability, high radiation stability, and high aging stability. It is also an object of the present invention to provide a method for manufacturing the housing simply and reliably.

Such a task is solved by the subject matter of the independent claims. Preferred and further configurations are the subject of the dependent claims.

In one embodiment, the surface mountable housing preferably comprises an assembly surface, a first connection lead, a second connection lead, and a housing body provided for assembly of the housing. The housing body includes a connection region for mechanically connecting the first connection lead and the second connection lead. The housing body comprises a surface area which at least partially covers the connection area on the side facing away from the assembly surface. The material of the connection area and the material of the surface area are different.

That is, the housing body comprises two partial regions which can be optimized in particular for different properties, taking into account various properties.

The connection area and the surface area are preferably based on the polymer material. Unlike ceramic materials, polymer materials can be processed simply and inexpensively.

The connection region preferably comprises a high temperature resistant polymer material. For example, epoxy or thermoplastic materials such as PPA, LCP (liquid crystal polymer), or PEEK are suitable.

In this regard, high temperature resistance means in particular that the material withstands a temperature of at least 250 ° C., preferably at least 400 ° C., without exhibiting significant degradation or deformation. The risk of damaging the housing, for example by soldering, during assembly of the housing is thus reduced.

The material of the connection region is preferably selected so that it has good adhesion to the connection leads and mechanically stably interconnects the connection leads. The material of the connection region can be chosen almost independently of its optical properties. In particular, the material may be formed, for example, in black, to absorb radiation in the visible light spectral region.

The surface area is preferably formed such that it has a high radiation stability, in particular higher radiation stability than that of the ultraviolet radiation region.

In one preferred configuration, the material of the surface region comprises silicon. Silicones are characterized by high radiation stability.

In addition, the material of the surface region is preferably filled with particles which reflect electromagnetic radiation, in particular radiation in the visible light spectral region. For example, titanium dioxide particles are suitable.

The housing body preferably extends in a vertical direction between the assembly surface and the top surface, ie in a direction extending perpendicular to the assembly surface. The upper surface is preferably formed at least in part by the surface area.

At least one region of the upper surface preferably extends beyond the first connecting lead and / or the second connecting lead in the vertical direction. In such a region, it is preferable that the upper surface is formed entirely by the surface region.

With such a surface area, the connection area lying underneath when viewed from the top can be protected from radiation, and therefore can be used in the connection area even if the material exhibited very severe deterioration due to radiation when used alone in the housing body. Will be.

The outer surface, which borders the housing body in the lateral direction, ie in the direction extending along the assembly surface, is preferably formed by the surface region only in part, in particular only in the region in contact with the upper surface.

In a preferred configuration, the housing body has a recess provided for fixing the optoelectronic semiconductor chip on the side facing away from the assembly surface. In such a recess, a semiconductor chip may be fixed and electrically connected to the first connection lead and the second connection lead.

In one preferred configuration, the surface area forms the side of the recess. In other words, it is ensured that the portion of the housing body that is most strongly exposed to the radiation produced during operation of the semiconductor chip has a sufficiently high radiation stability.

In one preferred configuration, the first connecting lead and / or the second connecting lead extends partially through the housing body completely in a direction extending perpendicular to the assembly surface. In other words, at least one connection lead is preferably capable of electrical contact with both connection leads from the assembling surface.

In the optoelectronic device including the housing described above, it is preferable that the optoelectronic semiconductor chip is disposed in the housing, and further preferably electrically conductively connected with the first connection lead and the second connection lead. In addition, the semiconductor chip is preferably embedded in encapsulation which at least partially contacts the surface area.

Encapsulation may be formed in multiple layers. For example, the partial layer in contact with the side of the semiconductor chip may be formed to reflect the radiation generated in the semiconductor chip. The partial layer of encapsulation covering the semiconductor chip on the opposite side of the carrier is preferably formed transparent or at least translucent to the radiation produced. In addition, radiation conversion material and / or diffusion material may be embedded in the encapsulation or at least in a partial layer of the encapsulation.

In the method of manufacturing the housing for an optoelectronic device, the first connection lead and the second connection lead are provided according to one embodiment. The connecting leads are partly molded by a molding compound for forming the connecting area of the housing body. The connection region mechanically interconnects the first connection lead and the second connection lead. In order to form the surface area of the housing body, the connecting area is partially molded by the second molding compound.

That is, the formation of the housing body consists of two molding steps which are performed sequentially. It is preferable that the material of the first molding compound and the material of the second molding compound be different from each other.

In a preferred configuration, the connecting and / or surface areas are produced by casting, injection molding, or transfer molding.

In another preferred configuration, a cleaning step is performed to remove material of the first molding compound between the molding with the first molding compound and the molding with the second molding compound. Alternatively, the cleaning step may also be performed after molding with the second molding compound.

The cleaning step can be carried out, for example, by plasma treatment, by electrolysis, or mechanically, for example by particle jets with or without liquids.

Alternatively or complementarily, a cleaning step may be performed after the molding of the connection region to remove the second molding compound.

In the method, the connection leads are preferably present in a composite, which is particularly intended for producing multiple housings simultaneously. After molding with the first molding compound and the second molding compound, the housings can be separated individually from the composite. It is preferable that the outer surface of the housing body is formed upon such separation. In other words, the housing is made of a composite and at least one outer surface of the housing is created when the composite is separated into a plurality of individual housings.

The method described above is very suitable for manufacturing the housing described in detail above. The features described in connection with the housing can thus also be cited for the method and vice versa.

Further features, configurations, and suitability will become apparent from the embodiments described below in conjunction with the accompanying drawings. In the accompanying drawings,
1 is a schematic cross-sectional view of one embodiment of a housing;
2A-2D show one embodiment of a method of manufacturing a housing based on intermediate steps schematically shown in cross section;
3 is a schematic cross-sectional view of a first embodiment of an optoelectronic device;
4 is a schematic cross-sectional view of a second embodiment of an optoelectronic device.
In the accompanying drawings, components that are the same, the same type, or the same function each have the same reference numerals.
The mutual size ratios of the accompanying drawings and the components shown in the accompanying drawings should not be considered to be to scale. Rather, individual elements may be exaggeratedly illustrated for greater expressiveness and / or better understanding.

In Fig. 1 an embodiment of the housing is shown in a schematic cross sectional view, in which such a housing 1 is formed as a surface mountable housing provided for fixing a semiconductor chip.

The housing 1 comprises a housing body 2 formed as a polymer based plastic mold. The housing body 2 is molded in the first connecting lead 31 and the second connecting lead 32. The first connecting lead and the second connecting lead form a lead frame of the housing 1.

The housing body 2 comprises a connecting area 21 and a surface area 22 directly in contact with the connecting area. The connection area 21 is in direct contact with the first connection lead 31 and the second connection lead 32 and mechanically interconnects the connection leads. The housing body, in particular the connection area and the surface area, is preferably formed to be electrically insulated. In addition, the connection region forms an assembly surface 11 provided for assembly of the housing.

The surface area 22 is formed on the side of the connection area 21 facing away from the assembly surface 11 and forms the surface 12 of the housing body 2. It is preferred that the mechanical stability is already ensured by the connection area. That is, the material of the surface area can be selected in consideration of other aspects, for example in consideration of radiation stability or simple processability.

The connecting leads 31 and 32 each have an undercut 35 in side view, which undercut 35 is formed in an exemplary step shape. By such an undercut, the engagement of the connection leads with the housing body 2, in particular the connection area 21, is improved. Thereby, the mechanical stability of the housing is improved.

The housing body 2 extends in a vertical direction between the assembly surface and the upper surface of the housing body, ie, in a direction extending perpendicular to the assembly surface 11. A recess 25 is formed in the housing body 2 from the top surface 12. In such a recess, the connection leads 31, 32 are partially exposed.

The surface area 22 of the housing body 2 forms the side 250 of the recess 25. The housing body includes a frame shaped area 251 that surrounds the recess in the lateral direction. In the region in the form of a frame, the upper surface 12 of the housing body 2 is completely formed by the surface region 22.

In the recess 25, the bottom surface 252 of the housing body 2 is preferably formed entirely by the connecting region 21. Such bottom surface is fastened coplanar with the connection leads 31 and 32.

When assembling the optoelectronic semiconductor chip to the housing 1, among other things, the side surface 250 of the recess and the top surface 12 of the housing body 2 are exposed to radiation of the semiconductor chip. By the surface area 22, the connection area 21 is protected from radiation of the semiconductor chip.

On the other hand, the outer surface 26 of the housing body 2 extending between the assembly surface 11 and the upper surface 12 is only exposed to relatively small radiation strength. Therefore, in the region of the outer surface 26, the connection region 21 may be exposed. Such an outer surface, which is formed in part by the connection region and partly by the surface region, can be simply formed when the connection region and the surface region are separated into pieces by complete cutting at the time of manufacture. However, unlike the embodiment shown, the surface area 22 may completely cover the connecting area 21 on the side of the housing body towards the outer surface to form the outer surface 26.

The connecting leads 31, 32 extend partially through the housing body 2, in particular in the connecting area 21, in part in the vertical direction. For external electrical contact of the housing body on the assembly surface side, the first external contact surface 311 of the first connection lead 31 facing the assembly surface 11 and the second external contact surface of the second connection lead 32. 321 is provided.

The connection leads 31 and 32 form a first connection surface 312 or a second connection surface 322 provided for conductive connection with the semiconductor chip on the side facing the upper surface 12 side of the housing body 2. Doing.

Surface area 22 is preferably based on silicon. Silicon is characterized by high stability against electromagnetic radiation, in particular ultraviolet radiation. In order to increase the reflectance of the surface area, the silicon is preferably filled with particles having high reflectance for radiation in the visible light spectrum region and / or the ultraviolet spectral region. For example, titanium dioxide particles are suitable.

The surface area preferably has a thickness of at least 30 μm. The thicker the surface area, the larger the particles can be embedded in the surface area. The thickness of the surface area is preferably from 100 μm including 100 μm to 300 μm including 300 μm.

On the other hand, the material of the connection region 21 does not need to be stable to radiation. In particular, it is possible to use epoxy materials that are typically used for encapsulation of electronic devices. Such epoxy materials, which are typically black, are characterized by high mechanical stability, good adhesion to the metals typically used in lead frames, and low thermal resistance, and are inexpensive to obtain due to their widespread use in electronic devices. have.

In addition, the material of the connection region 21 may comprise a hybrid material of epoxy and silicon, wherein the epoxy ratio is from 20% including 20% to 80% including 80%, very preferably. It is preferred that it is from 30% including 30% to 70% including 70%.

Alternatively, the connection region 21 may be formed of other high temperature resistant materials, in particular thermoplastics such as epoxy and silicone, hybrid materials of PPA (polyphthalamide), LCP (liquid crystal polymer), or PEEK (polyetheretherketone). It may also include.

One embodiment of a method of manufacturing a housing is schematically illustrated in cross-section in FIGS. 2A-2D. For the sake of simplicity, only one housing is shown. However, it is preferable to produce the individual housings by manufacturing the housings in a composite in which the regions provided in the housing are arranged next to each other, in particular in the form of stripe or matrix, and separating the composites individually.

As shown in FIG. 2A, a lead frame including a first connection lead 31 and a second connection lead 32 is provided. Such a lead frame may be formed of a flat copper plate, which may be provided (not explicitly shown), for example, in whole or at least in part to improve solderability. Such coatings may include, for example, silver, nickel, gold, or palladium, but metal alloys having at least one of the materials, such as nickel-gold or nickel-palladium-gold. In addition, the connecting leads 31 and 32 are each provided with undercuts 35 for the purpose of improving mechanical engagement with the housing body to be molded later. Connection leads with such undercuts may be produced, for example, by etching and / or mechanically, such as by extrusion, stamping, and / or punching.

As shown in FIG. 2B, the first connection lead 31 and the second connection lead 32 are molded by the first molding compound to mechanically and stably interconnect. Particularly suitable for molding are transfer molding methods or injection molding methods. The hardened molding compound forms the connection area 21 of the housing body 2.

In the next step, the connecting region 21 is partially molded by the second molding compound to form the surface region 22 of the housing body 2. The connection region is preferably molded only on the side opposite the assembly surface provided for assembly of the finished housing.

The starting material of the molding compound can be present in the liquid phase or as a solid, respectively.

Prior to molding with the second molding compound, to remove the material of the first molding compound, for example a plasma treatment, in particular an electrolysis treatment in conjunction with a high pressure water jet cleaning, a particle jet with or without additional liquid, or CO ₂ washing may be performed by washing. Thereby, the material of the unwanted molding compound on the connection leads 31, 32 can be removed.

In order to remove the material of the second molding compound, such a cleaning step can also be carried out after molding by the second molding compound.

After forming the housing body comprising the connecting area 21 and the surface area 22, the outer surface 26 of the housing 1 is created when the composite is separated into a plurality of individual housings. The separation into pieces can be carried out mechanically, for example by sawing or stamping. Alternatively or complementarily, chemical treatment, such as wet chemical or dry chemical etching or irradiation with coherent radiation, such as laser radiation, may also be used.

In order to manufacture an optoelectronic device comprising such a housing, an optoelectronic semiconductor chip of the optoelectronic device is already disposed in the housing and electrically conductively connected with the connection leads 31, 32, and in some cases, encapsulated and / or encapsulated It is preferable to carry out the separation into individual housings after having an optical instrument such as a focusing lens.

A first embodiment of a photovoltaic device comprising a housing described with reference to FIGS. 1 and 2A-2D is schematically shown in cross section in FIG. 3. Such an optoelectronic device 10 comprises a housing 1 in which a semiconductor chip 4 is arranged. The semiconductor chip 4 includes a semiconductor body 43 having a semiconductor layer sequence epitaxially manufactured. The semiconductor layer sequence includes an active region 40 prepared for the generation of radiation, which active region 40 is disposed between the first semiconductor layer 41 and the second semiconductor layer 42 having different conductivity types. do.

The semiconductor body 43 is disposed on the carrier 45 which mechanically stabilizes the semiconductor body 43. The growth substrate that was used to grow the semiconductor layer sequence of the semiconductor body can be removed as it is no longer needed for mechanical stabilization.

The first semiconductor layer 41 facing the carrier 45 is electrically connected to the first contact surface 461 provided for the contact of the semiconductor chip by the first connection layer 46. The first contact surface is disposed in the region of the first connection layer 46 exposed by the removal of the semiconductor body 43.

In the semiconductor body 43, at least one recess 44 is formed from the side facing the carrier 45, the recess 44 through the active region 40 facing the opposite side of the carrier. Extend into layer 42. The second semiconductor layer 42 conducts through the carrier 45 and the second contact surface 471 disposed on the side of the carrier 45 facing away from the semiconductor body 43 by the second connection layer 47. Connected.

The semiconductor body 43 is mechanically and stably electrically connected to a carrier, for example, a silicon carrier or a germanium carrier, by a connecting layer 50, such as a solder or conductive adhesive layer.

Between the first connection layer 46 and the second connection layer 47, an insulating layer 48, for example an oxide layer or a nitride layer, is formed which electrically insulates the connection layers from each other. Such insulating layer 48 also covers the side of the recess 44 to avoid electrical shorts in the active region 40.

There is no external electrical contact on the radiant exit surface of the semiconductor body 43 facing away from the carrier 45, so that radiation generated in the active region during operation of the semiconductor chip is shielded. In order to increase the decoupling efficiency, a structure 49, for example a roughening, may be provided on the radiation exit surface of the semiconductor chip 4 facing away from the carrier 54.

The second contact surface 471 is electrically connected with the first connecting layer 31 by, for example, a solder or a conductive adhesive layer. The first contact surface 471 is electrically conductively connected with the second connecting layer 32 of the housing 1 via a connecting line, for example via a wire bonding connection.

The semiconductor chip 4 is embedded in the encapsulation 7. The encapsulation 7 is formed in multiple layers in this embodiment. The first layer in contact with the side of the semiconductor body 4 is formed as a reflective layer 72. For example, the reflective layer may be formed as a silicon layer in which particles, such as titanium dioxide particles, are embedded to increase the reflectance. Such a reflective layer allows radiation that would otherwise leak laterally out of the semiconductor chip 4 to be directly reflected back to the semiconductor chip 4 and subsequently exited from the upper side radiation exit surface.

On the reflective layer 72, a second partial layer of encapsulation configured as a radiation transmissive layer 71 is formed. Such a radiation transmitting layer 71 covers the radiation exit face of the semiconductor chip 4. In the transmission layer 71, a radiation conversion material may be embedded to completely or at least partially convert radiation generated in the semiconductor chip 4. Such radiation converting material may be evenly or nearly uniformly distributed in the permeable layer 71. Alternatively, the radiation converting material may be formed non-uniformly in the transmission layer 71. For example, the radiation converting material may be formed mainly at the interfaces with the reflective layer 72 and / or at the interfaces with the semiconductor chip 4 due to sedimentation.

A second embodiment of the optoelectronic device is shown schematically in cross section in FIG. Such a second photovoltaic device is almost identical to the first embodiment described with reference to FIG. 3. However, unlike the first embodiment, the second semiconductor layer 42 disposed on the side of the active region 40 facing away from the carrier is in electrical contact by the upper side second contact surface 471. The first semiconductor layer 41 facing the carrier is in conductive contact by the first contact surface 461 via the carrier.

The first contact layer 46, for example a silver layer, serves as a mirror layer for radiation generated in the active region 40.

In addition, unlike the first embodiment, the radiation conversion element 8 is arranged on the semiconductor body 43. Such radiation conversion element 8 is preferably formed as a prefabricated plate which is fixed to the semiconductor body 43 by an adhesive layer, for example a silicon layer. In order to improve the expressability, the adhesive layer is not explicitly shown.

The radiation conversion element 8 may for example be formed as a ceramic plate in which particles prepared for radiation conversion are bonded to ceramic.

Alternatively, the radiation conversion element 8 may be formed by a matrix material in which the radiation conversion material is embedded, for example epoxy or silicon.

In addition, the transmission layer 71 is configured to form the optical element 73 differently from the first embodiment, for example, to form a convex lens that focuses radiation.

Of course, the semiconductor chip described with reference to FIG. 4 may also be used in the embodiment shown in FIG. 3. The housing is also suitable for semiconductor chips in which the growth substrate is not removed or only partially removed. The housing may be formed so that a plurality of semiconductor chips can be fixed to the housing.

In addition, in the above-described embodiments, the reflective layer 72 may be omitted. In that case, radiation leaking laterally from the semiconductor chip 4 may be diverted from the side surface 250 of the recess 25 toward the top surface 12.

The invention is not limited by the description based on the examples. Rather, the present invention includes any new feature and combination of features even if the feature or combination is not expressly described in the claims or the embodiments, in particular it includes any of the features of the claims. It includes a combination of.

Claims (15)

As the housing 1 for the photoelectric element 10,
The housing 1 comprises an assembly surface 11, a first connection lead 31, a second connection lead 32, and a housing body 2, which are provided for assembly of the housing;
The housing body 2 comprises a connecting region 21 which mechanically interconnects the first connecting lead 31 and the second connecting lead 32;
The housing body 2 comprises a surface area 22 at least partially covering the connection area 21 on the side facing away from the assembly surface 11;
A housing characterized in that the material of the connection area 21 and the material of the surface area 22 are different. The housing as claimed in claim 1, wherein the housing body comprises a recess (25) provided for fixing the semiconductor chip on the side facing away from the assembly surface. The housing as claimed in claim 2, wherein the surface area forms a side (250) of the recess. The housing as claimed in claim 1, wherein the connection area and the surface area are each based on a polymer material. The housing as claimed in claim 1, wherein the material of the surface area is filled with particles reflecting electromagnetic radiation. The housing of claim 1, wherein the material of the surface area comprises silicon. 7. A housing according to any one of the preceding claims, wherein the connection region comprises a high temperature resistant polymer material. 8. A housing according to any one of the preceding claims, wherein the first connecting lead and the second connecting lead extend partially through the housing body partially in a direction perpendicular to the assembly surface. The method of claim 1,
The housing body comprises a recess provided for fixing the semiconductor chip on the side facing away from the assembly surface;
The surface area forms the side of the recess;
The material of the surface area comprises silicon filled with particles which reflect electromagnetic radiation;
The connection region comprises a high temperature resistant polymer material. 10. An optoelectronic device (10) comprising a housing (1) according to any one of the preceding claims,
An optoelectronic device, characterized in that an optoelectronic semiconductor chip (4) is arranged in the housing and is electrically conductively connected with the first and second connection leads, and the semiconductor chip is embedded in an encapsulation (7) which partially contacts the surface area. As a method of manufacturing the housing (1) for the photoelectric element 10,
a) providing a first connection lead 31 and a second connection lead 32;
b) the connection leads 31, by a first molding compound for forming a connection region 21 of the housing body 2, which mechanically interconnects the first connection lead 31 and the second connection lead 32. Partially molding 32);
c) partially molding the connection region (21) by a second molding compound for forming the surface region (22) of the housing body (2). The manufacturing method according to claim 11, wherein the connection area and the surface area are produced by casting, transfer molding or injection molding. 13. A process according to claim 11 or 12, characterized in that a cleaning step is carried out between b) and c) to remove material of the first molding compound. 14. A process according to any one of claims 11 to 13, characterized in that after step c) a cleaning step for removing the material of the second molding compound is carried out. The manufacturing method according to any one of claims 11 to 14, wherein the housing according to any one of claims 1 to 9 is manufactured.

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