Patent ID: 12199218

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIGS.1A,1B and1Cshow an exemplary embodiment I of an optoelectronic semiconductor component1. The optoelectronic semiconductor component1comprises an optoelectronic semiconductor chip2and a carrier10, on which the optoelectronic semiconductor chip2is arranged. The optoelectronic semiconductor chip2has a radiation exit surface2A and side surfaces2B running transverse, preferably perpendicular, with respect to the radiation exit surface2A. A main axis M of the radiation exit surface2A runs through a center of the radiation exit surface2A and preferably is an axis of symmetry of the optoelectronic semiconductor chip2and the optoelectronic semiconductor component1.

Furthermore, the semiconductor component1comprises a conversion element3arranged on the semiconductor chip2and laterally projecting beyond the semiconductor chip2. Moreover, the semiconductor component1comprises a reflective element9laterally surrounding the optoelectronic semiconductor chip2and supporting the laterally projecting part of the conversion element3. Especially, all side surfaces2B of the optoelectronic semiconductor chip2are covered, at least partly, preferably completely, by the reflective element9. The semiconductor component1further comprises a dome-like encapsulant16spanning the carrier10and especially covering the conversion element3.

The conversion element3comprises a stack of several conversion layers4,5,6,7,8with different lateral extents L1, L2, L3, L4, L5. Here, the lateral extent L decreases from a first layer4which is closest to the radiation exit surface2A to a last layer8which is most distant from the radiation exit surface2A. Especially, the lateral extent L in all possible lateral directions decreases from the first layer4to the last layer8(seeFIG.1B). In other words, a lateral size of the conversion layers4,5,6,7,8decreases from the first layer4to the last layer8, and the conversion layer closer to the radiation exit surface2A laterally projects beyond the one further away from the radiation exit surface2A on all sides.

In particular, the lateral extent L decreases gradually from the first layer4to the last layer8. In other words, considering two adjacent conversion layers of the conversion element3, the one closer to the radiation exit surface2A has a greater lateral extent L than the one further away from the radiation exit surface2A.

The conversion element3or conversion layers4,5,6,7,8is/are arranged symmetrically with respect to the main axis M of the radiation exit surface2A. The conversion layers4,5,6,7,8have a rectangular, preferably square shape in plan view of the optoelectronic semiconductor component1. And the stack of layers4,5,6,7,8or the conversion element3may follow the shape of a pyramid or a truncated pyramid (seeFIG.1B).

By means of the conversion layers4,5,6,7,8, whose lateral extent L decreases from the first to the last layer4,8, the conversion element3comprises an inner region3A arranged at the main axis M of the radiation exit surface2A and several outer regions3B,3C,3D,3E laterally surrounding the inner region3A, wherein the inner region3A has a greater vertical extent V or thickness than the outer regions3B,3C,3D,3E. In particular, the vertical extent V of each region3A,3B,3C,3D,3E correlates to the number of layers contained in the respective region. Moreover, the lateral extent L of each region3A,3B,3C,3D,3E is identical to the lateral extent L of a top layer of the respective region.

In order to produce the conversion element3, a conversion material is applied layer after layer to the radiation exit surface2A, in particular by means of spray coating. By way of example, a first spraying burst can be produced for producing the first layer4. A second spraying burst can be produced for producing the second layer5and so on. A pause can be interposed between the spraying bursts, wherein a spraying medium used can solidify to form a conversion layer in the pause. The conversion layers4,5,6,7,8of different lateral extents L are produced by masks having different sizes of mask openings, wherein the spraying medium is sprayed into the mask openings. Especially, the process starts with a mask having the greatest mask opening in order to produce the first layer4and continues with masks whose mask openings are gradually reduced from layer to layer.

Preferably, the conversion layers4,5,6,7,8are formed from the same conversion material. This has the effect that all conversion layers4,5,6,7,8convert the primary radiation to the same secondary radiation. Furthermore, the conversion layers4,5,6,7,8are preferably formed with the same thickness V. For example, the conversion layers4,5,6,7,8can each have a thickness of 10 μm to 15 μm.

The reflective element9contains or consists of a diffusely reflective material such as TiO2 or aluminium. Moreover, the reflective element9comprises a concavely curved surface9A, where a part of the conversion element3is arranged in a form-fitting manner and thus is also concavely curved. This helps achieve an even distribution of radiation over a large angle range of the radiation emitted by the optoelectronic semiconductor component1.

The carrier10comprises a carrier body11and a first and a second contact structure12,13with a contact region12A,13A of the first and the second contact structure12,13respectively being arranged on a front surface11A of the carrier body11. Moreover, the first and the second contact structure12,13each comprise a contact region12B,13B arranged on a back surface11B of the carrier body11as well as a contact region extending through the carrier body11in a vertical direction and connecting the front side contact region12A,13A to the back side contact region12B,13B. This arrangement of the first and second contact structures12,13allows the semiconductor chip2to be electrically connected at the front side of the carrier10, whereas the semiconductor component1can be electrically connected at the back side of the carrier10.

The first and second contact structures12,13may be formed from a metal or metal compound, whereas the carrier body11may be formed from a semiconductor or ceramic material.

Moreover, the carrier10comprises a mounting structure14, where the semiconductor chip2is attached to the carrier10, for example by means of a solder or adhesive bond. The mounting structure14extends from the front surface11A of the carrier body11through the carrier body11up to the back surface11B of the carrier body11. Advantageously, the mounting structure14is thermally conductive and helps dissipate heat from the semiconductor chip2. Suitable materials for the mounting structure14are metals or metal compounds such as copper or compounds of copper, for example.

The optoelectronic semiconductor chip2arranged on the carrier10comprises a semiconductor layer sequence (not shown) which has an active layer suitable for generating primary radiation, and a first and a second electrical connecting layer (not shown), wherein the first and the second electrical connecting layer are arranged at a rear side opposite the front side and are electrically insulated from one another by means of a separating layer, wherein the first electrical connecting layer, the second electrical connecting layer and the separating layer overlap laterally, and a partial region of the second electrical connecting layer extends from the rear side through a breakthrough in the active layer in the direction of the front side. In particular, the first electrical connecting layer and the second electrical connecting layer each have an electrical contact area which is suitable for electrically contacting the semiconductor chip1from its front side. Here, the electrical contact areas are electrically connected with the respective contact structure12,13by means of a wire bond15.

The reflective element9fills interspaces17between the semiconductor chip2and the first and second contact structures12,13. This helps reduce radiation losses because the impinging radiation can be reflected versus a radiation emitting side of the semiconductor component1.

The encapsulant16can be formed from a molding compound. In particular, the molding compound is applied in a form-fitting manner to the semiconductor chip2provided with the conversion element3and the reflective element9. The encapsulant16may be formed dome-like from a translucent material such as silicone or an epoxy.

During operation, the semiconductor component1emits mixed-colored radiation, which means in particular that the mixed-colored radiation comprises portions of radiation of at least two different wavelengths such as a primary and a secondary radiation.

Especially, the optoelectronic semiconductor chip2emits primary radiation, wherein a first (peak) wavelength or a first wavelength range can be assigned to the primary radiation. The first (peak) wavelength or first wavelength range preferably is in the visible range. For example, the optoelectronic semiconductor chip2emits blue primary radiation. Furthermore, the conversion element3converts at least part of the primary radiation into secondary radiation. The secondary radiation can be assigned a second wavelength range or a second (peak) wavelength, which in particular is greater than the first (peak) wavelength or wavelength range.

The conversion element comprises, in particular, at least one or a plurality of conversion substances suitable for wavelength conversion. By way of example, the primary radiation may be at least partly converted into green and/or red and/or yellow light by the conversion element, such that the semiconductor component1emits white light.

The optoelectronic semiconductor chip2emits primary radiation through the radiation exit surface2A, and as the conversion element3is arranged on the radiation exit surface2A, primary radiation emitted from the optoelectronic semiconductor chip2can easily enter the conversion element3. Here, a radiation distribution of the primary radiation emitted by the optoelectronic semiconductor chip2is such that a majority of the radiation is emitted towards the main axis M of the radiation exit surface2A. Advantageously, the reflective element9helps achieve this radiation distribution because radiation coming from the semiconductor chip2and impinging on the reflective element9is reflected towards the radiation exit surface2A.

By means of the conversion element3, which has a greater vertical extent Vat or around the main axis M of the radiation exit surface2A than at its edges, a conversion degree can be achieved which is higher at or around the main axis M of the radiation exit surface2A than at the edges so that a ratio of the primary to the secondary radiation in the mixed-colored radiation can be essentially equalized over a wide angle range. This results in an improved color-over-angle characteristic of the optoelectronic semiconductor component1. The color-over-angle characteristic is described in more detail in connection with the following Figures.

FIGS.2A and2Bshow a comparative example of an optoelectronic semiconductor component1, which in contrast to the optoelectronic semiconductor component1described herein comprises a conversion element3having a single conversion layer.

FIGS.3to6show simulation results based on the embodiment I according toFIGS.1A to1Cand to the embodiment II according toFIGS.2A and2B.

FIG.3shows a table wherein a color of the mixed-colored radiation emitted by a semiconductor component according to embodiment I and embodiment II is specified for different angles α.

Angle α denotes the emission angle of the mixed-colored radiation with respect to the main axis M, wherein mixed-colored radiation emitted at the main axis M has an angle of 0°. The unit of angle α is degree (°).

The color can be specified by chromaticity coordinates, such as the Cx, Cy coordinates on the CIE 1931 chromaticity diagram. For example, the mixed-colored radiation emitted at α=0° has a white color, wherein the chromaticity coordinates of white color are Cx=Cy=⅓.

The first three columns of the table relate to the Cx-coordinate denoted “Cx”. The first column denotes angle α, the second column denotes the color coordinate Cx for embodiment II, and the third column denotes the color coordinate Cx for embodiment I.

Moreover, the last three columns of the table relate to the Cy-coordinate denoted “Cy”. The first column thereof denotes angle α, the second column denotes the color coordinate Cy for embodiment II, and the third column denotes the color coordinate Cy for embodiment I.

FIG.4shows a graph I of embodiment I and a graph II of embodiment II illustrating the color coordinate Cx over angle α specified in degrees.

FIG.5shows a graph I of embodiment I and a graph II of embodiment II illustrating the color coordinate Cy over angle α specified in degrees.

As becomes evident from the table and the graphs ofFIGS.4and5, the color deviation for embodiment II within a range of angles of 0°≤α≤90° is about 0.1 for both color coordinates Cx and Cy. However, the color deviation for embodiment I within the range of angles of 0°≤α≤90° is only about 0.02 for both color coordinates Cx and Cy. Thus, an improvement of 80% of the color-over-angle variation can be achieved with embodiment I in comparison to embodiment II.

In summary, the variation of the color of the mixed-colored radiation over a determined angle range can be reduced with the optoelectronic semiconductor component as described here by means of the conversion element.

FIG.6shows a simulated brightness B of mixed-colored radiation emitted by an optoelectronic semiconductor component according to embodiment I (graph I) in relation to embodiment II (graph II) at a color temperature of 5000 K and with a color-rendering index of 70.

As becomes evident fromFIG.6, the brightness loss with embodiment I comprising more conversion layers than embodiment II is only about 1.4%. However, if the conversion element uses a diffuser, the brightness loss is about 6%.

In summary, in addition to an improved color-over-angle characteristic, it is possible to achieve a better brightness with the optoelectronic semiconductor component as described above in comparison to a component using a diffusor as a means for improving the color-over-angle characteristic.

The invention is not restricted by the description on the basis of the exemplary embodiments. Rather, the invention encompasses any novel feature and also any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.