Embedded CSP LED device and manufacturing method thereof

Abstract

The invention discloses an embedded CSP (Chip Scale Package) LED (Light Emitting Diode) device and a manufacturing method thereof. The manufacturing method comprises the following steps: preparing a temporary fixing material, pasting an electrode surface of a flip LED chip on the temporary fixing material, laminating an incompletely cured silica gel / fluorescent powder composite sheet, removing the temporary fixing material, laminating an incompletely cured packaging material sheet, enabling the electrode surface of the flip LED chip to be in contact with the packaging material sheet, and packaging the flip LED chip on the packaging material sheet. The method comprises the following steps: pressing an upper copper foil, forming a blind hole, filling the blind hole with a copper material, etching a circuit pattern and a round hole on the copper foil, covering the etched area of the copper foil with ink, and carrying out chemical plating and cutting on the surface of the patterned copper foil. In the invention, the six surfaces of the LED chip are all elaborately wrapped by the high-quality organic material or metal, so that the chip is ensured to be tightly combined with the packaging material, and the risk of splitting or falling off is greatly reduced. The whole packaging process is simple and easy to operate, required tools are simple, and the method is more economical and practical.

Description

Technical Field

[0001] The invention belongs to the field of LEDs, and in particular relates to an embedded CSP LED device and a manufacturing method thereof. Background Art

[0002] Compared with ordinary LEDs, CSP LEDs have shown significant advantages in many aspects. First, CSP LED packaging technology has greatly reduced material waste and simplified the material cost structure by increasing the proportion of LED chips in the entire packaging area, thereby reducing production costs. Secondly, CSPLED adopts "flip chip and chip-level technology", has lower thermal resistance and higher electrical stability, effectively improves heating and heat dissipation problems, and improves product stability and reliability. In terms of light color accuracy, CSP LED lamp beads are more densely arranged, the light angle is larger, and the light color is more accurate. In contrast, traditional LEDs such as COB are more difficult to control in color. In addition, CSP LEDs have high power and extremely small light-emitting area. They are not only suitable for applications with strict optical design requirements, such as TV backlights, but also widely used in many fields such as car lights, flash lights, smart and healthy lighting. Especially in the application of mobile phone flash lights, CSPLED has quickly occupied the market with its high power and small light-emitting area. In summary, CSP LEDs are significantly superior to ordinary LEDs in terms of packaging process, cost, thermal resistance, electrical stability, light color accuracy, power, light-emitting area, and application fields.

[0003] However, in the prior art, CSP LEDs only use solder to fix the LED chip, and the solder has poor high-temperature performance and poor thermal conductivity. Solder is a weak point in CSP LEDs that is prone to failure. Chinese patent application CN108109993A discloses a CSP manufacturing method, including the following steps: (1) using a base plate as a carrier and attaching a high-temperature film to the base plate; (2) placing a gasket on the high-temperature film, the gasket is provided with a plurality of hollow holes, and the hollow holes and the high-temperature film at the bottom form a receiving cavity; (3) fixing the chip in the receiving cavity, and the bottom of the chip is bonded to the high-temperature film; (4) spreading fluorescent material on the gasket; (5) using a pressing plate to press on the fluorescent material, so that the fluorescent material is squeezed into the receiving cavity and covers the four sides of the chip; (6) removing the gasket to form a plurality of independent CSPs on the high-temperature film; this scheme uses a fluorescent / silicone sheet to wrap the five sides of the flip-chip LED chip (except the side with the electrode), and the bonding force between the LED chip and the fluorescent / silicone sheet is weak, and the two are prone to delamination failure. In addition, this method uses gaskets to form encapsulated particles, and it is difficult to control the volume of the fluorescent / silicone sheet so that the fluorescent / silicone sheet just fills the cavity in the gasket.

[0004] Chinese patent application CN201911080159.8 discloses a flip-chip LED chip CSP manufacturing method, but the silica gel / phosphor packaging material in this method directly includes the chip, which will cause the chip to fall off easily. Chinese patent application CN202111043490.X discloses a CSP lamp bead packaging structure and its manufacturing process. In this application, the pad is enlarged by a copper substrate, but the LED chip is not connected to the copper substrate, which will make the chip fall off easily. Chinese patent application CN201811011561.6 discloses an LED flip-chip packaging device structure and preparation method. In this scheme, solder is used to connect the chip and the substrate, and solder is used to fix the LED chip. The solder has poor high-temperature performance and poor thermal conductivity. Solder is a weak point in CSP LED that is prone to failure. Summary of the invention

[0005] The purpose of the present invention is to provide a buried CSP LED device and a manufacturing method thereof, which can realize five-sided light emission of an LED chip, significantly improve light extraction efficiency and uniformity, and thus optimize lighting effects, based on the prior art.

[0006] The purpose of the present invention can be achieved by the following measures: A buried CSP LED device is manufactured by a method comprising the following steps: S1. Prepare a sheet of double-sided temporary fixing material; S2, attaching the electrode surface of the flip-chip LED chip to the temporary fixing material; S3, pressing the uncured silica gel / phosphor composite sheet onto the temporary fixing material, so that the silica gel / phosphor sheet tightly wraps the flip-chip LED chip; S4. Remove temporary fixing materials; S5, tightly pressing the silica gel / phosphor sheet and the flip-chip LED chip wrapped therein onto the packaging material sheet that is not completely cured, so that the electrode surface of the flip-chip LED chip is in contact with the packaging material sheet; S6, pressing a copper foil on the other side of the packaging material sheet, and then performing high temperature curing; S7, opening a blind hole above the electrode of the flip-chip LED chip by laser, wherein the blind hole area is within the chip electrode; S8, using a copper electroplating method to fill the blind holes opened in step S7 with copper material; S9, etching a circuit pattern on the copper foil, and etching a circular hole for relieving stress on the copper foil near the blind hole; S10, using ink to cover the etched area of ​​the copper foil; S11, performing chemical plating on the surface of the patterned copper foil to obtain a plating layer; S12, cutting the structure obtained in step S11 to obtain individual embedded CSP LED devices.

[0007] The present invention also includes a method for manufacturing an embedded CSP LED device, which also includes the above steps S1 to S12.

[0008] In step S1, the temporary fixing material needs to be easily peeled off from the surface of the object to be fixed, and no residue is left on the surface of the object to be fixed after peeling. The temporary fixing material is used to fix the flip chip. The materials that can be used for the temporary fixing material include: tape, high temperature film, UV film, etc.

[0009] In step S2, the electrode surfaces of the flip-chip LED chips (2) are attached to the temporary fixing material (1) in the form of an array by a high-precision chip mounter. The distance between the LED flip-chips is 100 μm-1000 μm.

[0010] In step S3, an incompletely cured silica gel / phosphor composite sheet is prepared, and the incompletely cured silica gel / phosphor composite sheet is pressed onto a temporary fixing material using a vacuum fast press, and the thickness of the pressed silica gel / phosphor sheet is greater than the thickness of the flip-chip LED chip by more than 30 μm. Incompletely cured in the present invention means that the material can still melt after heating and has adhesive force after melting.

[0011] The silica gel / phosphor composite sheet refers to a sheet containing silica gel and phosphor, and can be any silica gel / phosphor composite sheet currently used in the art.

[0012] In step S4, the temporary fixing material may be torn off by machine or manually.

[0013] In step S5, the silica gel / phosphor sheet (3) wrapping the flip-chip LED chip (2) is tightly pressed onto the packaging material sheet (4) that is not completely cured, so that the electrode surface of the LED chip (2) is in contact with the packaging material sheet (4), and the thickness of the packaging material sheet (4) is in the range of 30-70 μm. The packaging material includes silica gel, epoxy molding compound, glass fiber reinforced PP, etc.

[0014] In step S6, a copper foil is pressed onto the other side of the packaging material sheet (the side not in contact with the LED chip electrode), and then high-temperature curing is performed. The thickness of the copper foil (5) is 30-200 μm, and the curing temperature is 140-160°C.

[0015] In step S7, a blind hole can be opened above the electrode of the flip-chip LED chip (2) by using laser hole opening technology, and the blind hole area is within the chip electrode.

[0016] In step S8, copper material may be used to fill the blind hole opened in step S7 by copper electroplating technology. After the blind hole is filled with copper material, its surface is flush with the surface of the copper foil (5).

[0017] In step S9, a circuit pattern is etched on the copper foil, the connection between the positive and negative electrodes of the flip-chip LED chip is disconnected, and a circular hole for stress relief is etched on the copper foil near the blind hole. The etched circular hole is located between adjacent blind holes and has a hole diameter of 50-100 microns.

[0018] In step S10, the thickness of the ink covering the etched area is the same as the thickness of the copper foil.

[0019] In step S11, a chemical plating process is performed on the surface of the patterned copper foil (5), and the plating material includes tin, nickel, gold or silver.

[0020] In step S12, the structure described in step S11 is cut to form individual embedded CSP LED devices.

[0021] Beneficial effects of the present invention: In the solution of this application, the six sides of the LED chip are carefully wrapped with high-quality organic materials or metals to ensure that the chip is tightly combined with the packaging material, greatly reducing the risk of splitting or falling off. What is more worth mentioning is that the entire packaging process is simple and easy to operate, and the tools required are simple, which effectively reduces the manufacturing cost, making the solution more economical and practical.

[0022] The method of the present application can realize five-sided light emission of the LED chip, significantly improve the light output efficiency and uniformity, and thus optimize the lighting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flow chart of the manufacturing method of the present invention; Figure 2 It is a schematic diagram of the structure of the embedded CSP LED device of the present invention; In the figure, 1-temporary fixing material, 2-flip-chip LED chip, 3-silica gel / phosphor sheet, 4-packaging material sheet, 5-copper foil, 6-ink, 7-plating, 11-blind hole, 12-round hole, DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to the following examples.

[0025] Example 1 The method for manufacturing the embedded CSP LED device of the present invention comprises the following steps: S1. Prepare a sheet-shaped double-sided temporary fixing material (1), which is easy to be peeled off from the surface of the fixed object and leaves no residue on the surface of the fixed object after peeling. The materials that can be used include: tape, high temperature film, UV film, etc.

[0026] S2. The electrode surfaces of the flip-chip LED chips (2) are attached to the temporary fixing material (1) in the form of an array by a high-precision chip mounter. The distance between the flip-chip LED chips is 100 μm-1000 μm.

[0027] S3, prepare an uncured silica gel / phosphor composite sheet, and use a vacuum fast press to press the silica gel / phosphor sheet (3) onto the temporary fixing material (1), so that the silica gel / phosphor sheet (3) tightly wraps the flip-chip LED chip (2). The thickness of the silica gel / phosphor sheet (3) is greater than the thickness of the flip-chip LED chip (2) by more than 30 μm.

[0028] S4. Remove the temporary fixing material (1) by machine or by hand.

[0029] S5. The silicone / phosphor sheet (3) wrapping the flip-chip LED chip (2) is tightly pressed onto the uncured packaging material sheet (4), so that the electrode surface of the LED chip (2) contacts the packaging material sheet (4), and the thickness of the packaging material sheet (4) is in the range of 30-70 μm. The packaging material includes silicone, epoxy molding compound, glass fiber reinforced PP, etc. A specific optimized pressing condition is: 5 Kgf / cm2, 5 min.

[0030] S6. Pressing a copper foil (5) onto the packaging material sheet (4) in the structure of step S5, wherein the thickness of the copper foil (5) is 30-200 μm. Then, the structure is placed in a high temperature environment for curing. A specific optimized pressing condition is: 5 Kgf / cm2, 5 min; high temperature curing temperature is 150°C.

[0031] S7. Using laser hole opening technology, a blind hole is opened above the electrode of the flip-chip LED chip (2), and the blind hole area is within the chip electrode.

[0032] S8. Fill the blind holes opened in step S7 with copper material using copper electroplating technology.

[0033] S9, etching a circuit pattern on the copper foil (5) to disconnect the connection between the positive and negative electrodes of the flip-chip LED chip (2). Etching a circular hole near the blind hole to relieve stress. The etched circular hole is located between adjacent blind holes and has a hole diameter of 50-100 microns.

[0034] S10, using ink to cover the etched area of ​​the copper foil (5). The thickness of the covering ink is the same as that of the copper foil (5).

[0035] S11, performing chemical plating on the surface of the patterned copper foil (5), and the material of the plating layer (7) can be selected from tin, nickel, gold, silver and the like.

[0036] S12, cutting the structure described in step 11 to form a separate embedded CSP LED device, the structure of which is as follows Figure 2 shown.

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A buried CSP LED device, characterized in that It is produced by a method comprising the following steps: S1. Prepare a sheet of double-sided temporary fixing material; S2, attaching the electrode surface of the flip-chip LED chip to the temporary fixing material; S3, pressing the uncured silica gel / phosphor composite sheet onto the temporary fixing material, so that the silica gel / phosphor sheet tightly wraps the flip-chip LED chip; S4, removing the temporary fixing material; S5, tightly pressing the silica gel / phosphor sheet and the flip-chip LED chip wrapped therein onto the packaging material sheet that is not completely cured, so that the electrode surface of the flip-chip LED chip is in contact with the packaging material sheet; S6, pressing a copper foil on the other side of the packaging material sheet, and then performing high temperature curing; S7, opening a blind hole above the electrode of the flip-chip LED chip by laser, wherein the blind hole area is within the chip electrode; S8, using a copper electroplating method to fill the blind holes opened in step S7 with copper material; S9, etching a circuit pattern on the copper foil, and etching a circular hole for relieving stress on the copper foil near the blind hole; S10, using ink to cover the etched area of ​​the copper foil; S11, performing chemical plating on the surface of the patterned copper foil to obtain a plating layer; S12, cutting the structure obtained in step S11 to obtain individual embedded CSP LED devices.

2. The embedded CSP LED device according to claim 1, characterized in that In step S1 , the temporary fixing material is an adhesive tape, a high temperature film or a UV film.

3. The embedded CSP LED device according to claim 1, characterized in that In step S2, the electrode surfaces of the flip-chip LED chips are attached to the temporary fixing material in the form of an array by a high-precision chip mounter; the distance between the flip-chip LED chips is 100 μm-1000 μm.

4. The embedded CSP LED device according to claim 1, characterized in that In step S3, a vacuum fast press is used to press the incompletely cured silica gel / phosphor composite sheet onto the temporary fixing material, and the thickness of the pressed silica gel / phosphor sheet is greater than the thickness of the flip-chip LED chip by more than 30 μm.

5. The embedded CSP LED device according to claim 1, characterized in that In step S5, the electrode surface of the flip-chip LED chip is in contact with a packaging material sheet, the thickness of the packaging material sheet is in the range of 30-70 μm; the packaging material includes silica gel, epoxy molding compound or glass fiber reinforced PP.

6. The embedded CSP LED device according to claim 1, characterized in that In step S6, the thickness of the copper foil (5) is 30-200 μm, and the curing temperature is 140-160°C.

7. The embedded CSP LED device according to claim 1, characterized in that In step S9, the etched circular holes are located between adjacent blind holes, and the hole diameter is 50-100 microns.

8. The embedded CSP LED device according to claim 1, characterized in that In step S10 , the thickness of the covered ink is the same as the thickness of the copper foil.

9. The embedded CSP LED device according to claim 1, characterized in that In step S11 , the plating material includes tin, nickel, gold or silver.

10. A method for manufacturing an embedded CSP LED device, characterized in that It includes steps S1 to S12 described in claim 1.

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