Chip-scale package light emitting device and manufacturing method thereof

Abstract

The invention discloses a chip-scale package light emitting device and a manufacturing method thereof. The light emitting device comprises a flip-chip LED chip and a package structure, wherein the package structure comprises a flexible buffer structure, a fluorescent structure and a transmitting structure, the flexible buffer structure comprises a top part and a side part, the top part is formed on an upper surface of the flip-chip LED chip, the side part is formed on a three-dimensional surface of the flip-chip LED chip, the top part is provided with a convex curved surface, the side part is provided with an outer edge surface, the outer edge surface is connected with the convex curved surface, the fluorescent structure is formed on the flexible buffer structure along the convex curved surface and the outer edge surface, the transmitting structure is formed on the fluorescent structure, and the hardness of the transmitting structure is not smaller than the hardness of the flexible buffer structure. Therefore, the flip-chip LED chip and the package structure have relatively excellent adhesion performance, and the light emitting device has relatively excellent reliability, space color uniformity, color temperature classification concentration and light emitting efficiency.

Description

technical field [0001] The present invention relates to a light-emitting device and a manufacturing method thereof, in particular to a chip-level packaging light-emitting device with a flip-chip LED chip and a manufacturing method thereof. Background technique [0002] LED (Light Emitting Diode) chips are commonly used to provide light sources for illumination, display or indication, and LED chips are usually disposed in a package structure (which may contain fluorescent materials) to become a light emitting device. [0003] With the development of LED technology, chip-scale package (chip-scale package, CSP) light-emitting devices have begun to receive a lot of attention in recent years due to their obvious advantages. Taking the most widely used white CSP light-emitting device as an example, it usually consists of a blue LED chip and a fluorescent structure covering the LED chip; wherein, the blue LED chip is usually a flip-chip LED chip with a top surface In addition, the...

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Problems solved by technology

[0005] However, since the CSP light-emitting device does not require additional sub-mounts such as substrates or brackets, the fluorescent structure in the CSP light-emitting device is only in contact with the LED chip; because the contact area between the two is quite limited, it often leads to a gap between the two. Insufficient bonding force; and the thermal expansion coefficient of the LED chip and the fluorescent structure usually has a significant difference. Under the temperature change generated during the operation of the light emitting device, the internal stress caused by the mismatch of the thermal expansion coefficient will make the fluorescent structure with insufficient bonding force The structure is easy to peel off from the LED chip (delamination), resulting in failure of the CSP light emitting device

This inherent characteristic seriously affects the reliability performance of existing CSP light emitting devices

[0006] Furthermore, during the manufacturing process of the existing CSP light-emitting device, the fluorescent material is first mixed in the binder, such as a polymer material, and then through molding, printing or spraying ) and other methods to form fluorescent structures; when fluorescent materials are mixed with polymer materials, fluorescent colloids (phosphor slurry) will be formed. When manufacturing fluorescent structures, the control of the geometric dimensions of fluorescent structures requires high precision. , in order to obtain accurate luminescent color control; and, the existing methods can only control the geometrical dimensions of the fluorescent structure, but it is difficult to control the distribution state of the fluorescent material in the fluorescent colloid (or fluorescent structure), while the distribution state of the fluorescent material is is the key factor to determine its luminous performance

Therefore, these two innate physical properties make it difficult for fluorescent materials to form a conformal coating, which increases the difficulty of achieving optical consistency in mass production of CPS light-emitting devices.

[0007] For example, when fluorescent colloid is used for molding (or printing) the fluorescent structure of CSP light-emitting devices, the relative position between multiple LED chips (forming an LED chip array) and the inner surface of the mold (or printing scraper and steel plate) The error will cause insufficient thickness consistency of the fluorescent structure formed on the upper surface and facade of multiple LED chips; at the same time, if it is necessary to separate multiple CSP light-emitting devices by cutting, the error in the cutting position of the fluorescent structure will make the LED The thickness of the fluorescent structure on the chip facade is difficult to control; coupled with the inability to effectively control the distribution of the fluorescent material in the colloid; these factors have resulted in the inability to form a conformal coating of the fluorescent material, so that the emitted light from the LED chip After the light passes through the fluorescent structure, its color is inconsistent, resulting in poor spatial color uniformity (spatial color uniformity), and color temperature (Correlated Color Temperature, CCT) grading (binning) concentration is also poor, resulting in a decline in production yield

[0008] In addition, if spraying is used to make the fluorescent structure, although the related problems encountered in the alignment error of the LED chip in the molding (or printing process) can be avoided, the fluorescent material is not easy due to the effect of gravity when spraying. Attached to the vertical facade of the LED chip, the fluorescent material is not easy to form a continuous distribution on the facade, which will cause the fluorescent material to be discontinuous in the polymer material on the facade of the LED chip, although the polymer material can be formed on the facade The transparent structure is continuously distributed, but due to the local lack of fluorescent materials, a large area of ​​continuous optically transparent "holes" is produced, so that blue light leaks from the holes, that is, it directly penetrates the packaging structure without wavelength conversion by fluorescent materials, resulting in The side of the CSP light-emitting device is easy to leak blue light, so that the color of the front light of the CSP light-emitting device is inconsistent with that of the side light to form a blue halo. Therefore, the existing spraying process cannot form a fluorescent material with a conformal coating; When the spraying method forms a thin fluorescent structure on the upper surface of the LED chip, since the fluorescent material and the polymer material have been pre-mixed to form a fluorescent colloid, the particle aggregation of the fluorescent material (usually granular) will make the fluorescent material Obvious distribution discontinuity appears, which will also form holes in the fluorescent material, resulting in spot (blue light spot) phenomenon; High, in addition to causing poor spatial color uniformity, it will also increase the damage caused by blue light to human eyes; at the same time, inconsistent distribution of fluorescent materials will lead to poor color temperature grading concentration; moreover, a large amount of blue light leakage will make fluorescent materials unable to Effective conversion of blue light wavelengths will also cause a decrease in light conversion efficiency

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