A buried CSP LED device and a manufacturing method thereof

Abstract

The application discloses a kind of embedded CSP LED devices and manufacturing method.It is made by the method comprising the following steps: preparing temporary fixing material, the electrode face of flip-chip LED chip is pasted on temporary fixing material, the silicon glue / fluorescent powder composite sheet that is not completely cured is pressed, remove temporary fixing material, the encapsulating material sheet that is not completely cured is pressed, the electrode face of flip-chip LED chip is contacted with encapsulating material sheet, the copper foil that is pressed on, open blind hole, use copper material to fill blind hole, etch circuit pattern and round hole on copper foil, use ink to cover the area that copper foil is etched off, plating is carried out on the surface of patterned copper foil, cutting.In the application, six faces of LED chip are carefully wrapped with high-quality organic material or metal, ensure that chip and encapsulating material are closely combined, greatly reduce the risk of splitting or falling off.The whole encapsulation process is simple and easy to operate, and the required tool is simple, more economical and practical.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of LED, in particular to a buried CSP LED device and a manufacturing method. BACKGROUND

[0002] Compared with ordinary LED, CSP LED has significant advantages in many aspects. First, CSP LED packaging technology greatly reduces material waste and simplifies material cost structure by increasing the proportion of LED chips in the entire packaging area, thereby reducing production costs. Second, CSP LED adopts "flip chip and chip level technology", which has lower thermal resistance and higher electrical stability, effectively improving the heat and heat dissipation problems, and improving the stability and reliability of the product. In terms of light color accuracy, CSP LED has more dense lamp bead arrangement, larger light emitting angle and more accurate light color. In contrast, traditional LED such as COB is more difficult to control color. In addition, CSP LED has high power and small light emitting area, which is not only suitable for applications with strict optical design requirements such as television backlighting, but also widely used in many fields such as car lights, flashlights, intelligent and healthy lighting, etc. Especially in the application of mobile phone flash, CSP LED quickly occupies the market with its high power and small light emitting area. In summary, CSP LED is significantly superior to ordinary LED in terms of packaging process, cost, thermal resistance, electrical stability, light color accuracy, power, light emitting area and application field, etc.

[0003] However, the existing CSP LED only uses solder to fix the LED chip, and the solder has poor high-temperature performance and poor thermal conductivity, which is a weak point of CSP LED that is prone to failure. Chinese patent application CN108109993A discloses a manufacturing method of CSP, comprising the following steps: (1) taking a bottom plate as a carrier plate and pasting a high-temperature film on the bottom plate; (2) placing a gasket on the high-temperature film, the gasket being provided with a plurality of hollow holes, and the hollow holes and the high-temperature film at the bottom surrounding a containing cavity; (3) fixing a wafer in the containing cavity, and the bottom of the wafer being bonded with the high-temperature film; (4) laying a fluorescent material on the gasket; (5) pressing the fluorescent material with a pressing plate, so that the fluorescent material is squeezed into the containing cavity and covers the periphery of the wafer; (6) removing the gasket to form a plurality of independent and separated CSPs on the high-temperature film; this scheme uses a fluorescent / silica gel sheet to wrap five surfaces of the flip LED chip (except the surface with electrodes), and the bonding force between the LED chip and the fluorescent / silica gel sheet is weak, and the two are prone to delamination failure. In addition, this method uses a gasket to form a packaging particle, which is difficult to control the volume of the fluorescent / silica gel sheet, so that the fluorescent / silica gel sheet just fills the cavity in the gasket.

[0004] Chinese patent application CN201911080159.8 discloses a flip LED chip CSP manufacturing method, but the silica gel / phosphor packaging material in the method directly includes the chip, which can cause the chip to easily fall off. Chinese patent application CN202111043490.X discloses a CSP lamp bead packaging structure and its manufacturing process, in which the copper substrate is expanded by a pad, but the LED chip is not connected with the copper substrate, which can cause the chip to easily fall off. Chinese patent application CN201811011561.6 discloses an LED flip chip packaging device structure and a preparation method, in which the solder is used to connect the chip and the copper substrate, and the solder is used to die bond the LED chip. The solder has poor high-temperature performance and poor thermal conductivity, and the solder is a weak point prone to failure in the CSP LED. SUMMARY

[0005] The purpose of the present application is to provide a buried CSP LED device and a manufacturing method capable of achieving five-face light emission of an LED chip, significantly improving light efficiency and uniformity, and thus optimizing the lighting effect on the basis of the prior art.

[0006] The purpose of the present application can be achieved by the following measures:

[0007] A buried CSP LED device is manufactured by a method comprising the following steps:

[0008] S1, preparing a sheet-shaped double-sided temporary fixing material;

[0009] S2, attaching an electrode surface of a flip LED chip to the temporary fixing material;

[0010] S3, pressing a silica gel / phosphor composite sheet that is not completely cured on the temporary fixing material, so that the silica gel / phosphor sheet tightly wraps the flip LED chip;

[0011] S4, removing the temporary fixing material;

[0012] S5, tightly pressing the silica gel / phosphor sheet and the flip LED chip wrapped thereby on a sheet of packaging material that is not completely cured, with the electrode surface of the flip LED chip being in contact with the sheet of packaging material;

[0013] S6, pressing a copper foil on the other surface of the sheet of packaging material, and then performing high-temperature curing;

[0014] S7, opening a blind hole above the electrode of the flip LED chip by laser, with the blind hole region being inside the chip electrode;

[0015] S8, filling the blind hole opened in step S7 with copper material by a copper electroplating method;

[0016] S9, etching a circuit pattern on the copper foil, and etching a stress relief hole on the copper foil near the blind hole;

[0017] S10, covering the etched area of the copper foil with ink;

[0018] S11, performing a plating process on the surface of the patterned copper foil to obtain a plated layer;

[0019] S12, cutting the structure obtained in step S11 to obtain a single embedded CSP LED device.

[0020] The application also includes a method for manufacturing an embedded CSP LED device, which also includes the above steps S1 to S12.

[0021] In step S1, the temporary fixing material needs to be easily peeled off from the surface of the fixed object, and no residue is left on the surface of the fixed object 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: adhesive tape, high-temperature film, UV film, etc.

[0022] In step S2, the electrode surface of the flip LED chip (2) is attached to the temporary fixing material (1) in an array form by a high-precision chip mounter. The distance between the LED flip chips is 100-1000 μm.

[0023] In step S3, a partially cured silicone / fluorescent powder composite sheet is prepared, and a vacuum fast press is used to press the partially cured silicone / fluorescent powder composite sheet onto the temporary fixing material. The thickness of the silicone / fluorescent powder sheet after pressing is greater than the thickness of the flip LED chip by more than 30 μm. The term "partially cured" in the present application refers to a material that can still be melted after heating, and has adhesive force after melting.

[0024] The silicone / fluorescent powder composite sheet refers to a thin sheet containing silicone and fluorescent powder. It can use the conventional silicone / fluorescent powder composite sheet in the field.

[0025] In step S4, the temporary fixing material can be torn off by machine or manually.

[0026] In step S5, the silicone / fluorescent powder sheet (3) wrapped around the flip LED chip (2) is tightly pressed onto the partially cured encapsulating material sheet (4), the electrode surface of the LED chip (2) is in contact with the encapsulating material sheet (4), and the thickness of the encapsulating material sheet (4) is in the range of 30-70 μm. The encapsulating material includes silicone, epoxy encapsulating material, glass fiber reinforced PP, etc.

[0027] In step S6, a copper foil is pressed on the other side of the sheet of encapsulating material (the side not in contact with the electrodes of the LED chip), 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.

[0028] In step S7, a blind hole is opened above the electrode of the flip-chip LED chip (2) by laser drilling technology, and the blind hole region is within the chip electrode.

[0029] In step S8, the blind hole opened in step S7 is filled with copper material by copper electroplating technology. After the blind hole is filled with copper material, the surface thereof is flush with the surface of the copper foil (5).

[0030] In step S9, a circuit pattern is etched on the copper foil, the connection between the anode and cathode electrodes of the flip-chip LED chip is disconnected, and a stress-relieving circular hole is etched on the copper foil near the blind hole. The etched circular hole is located between adjacent blind holes, and the hole diameter is 50-100 μm.

[0031] In step S10, the thickness of the ink covered in the etched region is the same as the thickness of the copper foil.

[0032] In step S11, a plating treatment is performed on the surface of the patterned copper foil (5), and the plating layer material includes tin, nickel, gold, or silver.

[0033] In step S12, the structure described in step S11 is cut to form a separate embedded CSP LED device.

[0034] Advantages of the present application:

[0035] In the scheme of the present application, the six sides of the LED chip are carefully wrapped with high-quality organic materials or metals, ensuring that the chip is tightly combined with the encapsulating material and greatly reducing the risk of splitting or falling off. More notably, the entire encapsulation process is simple and easy to operate, the required tools are simple, and the manufacturing cost is effectively reduced, making the scheme more economical and practical.

[0036] The method of the present application can achieve five-side light emission of the LED chip, significantly improving the light efficiency and uniformity, and thus optimizing the lighting effect. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a flowchart of the manufacturing method of the present application;

[0038] Figure 2 is a schematic diagram of the embedded CSP LED device structure of the present application;

[0039] In the figure, 1 - temporary fixing material, 2 - flip LED chip, 3 - silica gel / fluorescent powder sheet, 4 - encapsulation material sheet, 5 - copper foil, 6 - ink, 7 - plating layer, 11 - blind hole, 12 - round hole, DETAILED DESCRIPTION

[0040] The application will be further described below in conjunction with the accompanying drawings and examples, but the protection scope of the application is not limited to the following examples.

[0041] Example 1

[0042] The manufacturing method of the embedded CSP LED device of the application comprises the following steps:

[0043] S1, prepare a sheet-shaped double-sided temporary fixing material (1), which can be easily peeled off from the surface of the fixed object and has no residue on the surface of the fixed object after peeling. The materials that can be used include: adhesive tape, high-temperature film, UV film, etc.

[0044] S2, the electrode surface of the flip LED chip (2) is attached to the temporary fixing material (1) in an array form by a high-precision chip mounter. The distance between the LED flip chips is 100 μm-1000 μm.

[0045] S3, prepare a silica gel / fluorescent powder composite sheet that is not completely cured, and use a vacuum fast pressing machine to press the silica gel / fluorescent powder sheet (3) on the temporary fixing material (1), so that the silica gel / fluorescent powder sheet (3) tightly wraps the flip LED chip (2). The thickness of the silica gel / fluorescent powder sheet (3) is greater than the thickness of the flip LED chip (2) by more than 30 μm.

[0046] S4. Remove the temporary fixing material (1) by machine or manually.

[0047] S5, tightly press the silica gel / fluorescent powder sheet (3) wrapping the flip LED chip (2) on the not completely cured encapsulation material sheet (4), so that the electrode surface of the LED chip (2) is in contact with the encapsulation material sheet (4). The thickness of the encapsulation material sheet (4) is in the range of 30-70 μm. The encapsulation material includes silica gel, epoxy encapsulation material, glass fiber reinforced PP, etc. One specific optimized pressing condition is: 5 Kgf / cm2, 5 min.

[0048] S6, press the copper foil (5) on the encapsulation material sheet (4) in the structure described in step S5, and the thickness of the copper foil (5) is in the range of 30-200 μm. Then, the structure is placed in a high-temperature environment for curing. One specific optimized pressing condition is: 5 Kgf / cm2, 5 min; the high-temperature curing temperature is 150°C.

[0049] S7, a blind hole is opened above the electrode of the flip LED chip (2) by laser drilling technology, and the blind hole area is in the chip electrode.

[0050] S8, filling the blind hole opened in step S7 with copper material by copper electroplating technology.

[0051] S9, etching a circuit pattern on the copper foil (5) to disconnect the connection between the anode and cathode of the flip-chip LED chip (2). A round hole is etched near the blind hole to relieve stress. The etched round hole is located between adjacent blind holes, and the hole diameter is 50-100 microns.

[0052] S10, covering the etched area of the copper foil (5) with ink. The thickness of the ink is the same as that of the copper foil (5).

[0053] S11, performing electroplating treatment on the surface of the patterned copper foil (5), and the plating layer (7) material can be selected from tin, nickel, gold, silver and the like.

[0054] S12, cutting the structure described in step 11 to form a separate embedded CSP LED device, and the structure is as shown in Figure 2 .

[0055] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art, according to the technical solution and the inventive concept of the present application, can make equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method of fabricating a buried CSP LED device, the method comprising: It comprises the following steps: ​ S1, preparing a temporary fixing material with double sides in sheet shape; S2, sticking the electrode side of the flip-chip LED to the temporary fixing material; S3, pressing the incompletely cured silicone / fluorescent powder composite sheet to the temporary fixing material, so that the silicone / fluorescent powder composite sheet tightly wraps the flip-chip LED; S4, removing the temporary fixing material; S5, tightly pressing the silicone / fluorescent powder sheet and the flip-chip LED wrapped thereby to the incompletely cured encapsulating material sheet, with the electrode side of the flip-chip LED contacting the encapsulating material sheet; S6, pressing a copper foil to the other side of the encapsulating material sheet, and then performing high-temperature curing; S7, opening a blind hole above the electrode of the flip-chip LED by laser, with the blind hole region being within the chip electrode; S8, filling the blind hole opened in step S7 with copper material by copper electroplating method; S9, etching a circuit pattern on the copper foil, and etching a stress-relieving circular hole on the copper foil near the blind hole; the etched circular hole is located between adjacent blind holes, with a hole diameter of 50-100 microns; S10, covering the etched area of the copper foil with ink; S11, performing electroplating treatment on the surface of the patterned copper foil to obtain a plating layer; S12, cutting the structure obtained in step S11 to obtain a separate embedded CSP LED device.

2. The method of claim 1, wherein In step S1, the temporary fixing material is an adhesive tape.

3. The method of claim 1, wherein the method further comprises forming a passivation layer on the first and second electrodes. In step S1, the temporary fixing material is a high-temperature film.

4. The method of claim 1, wherein In step S1, the temporary fixing material is a UV film.

5. The method of claim 1, wherein In step S2, the electrode side of the flip-chip LED is stuck to the temporary fixing material in an array form by a high-precision chip mounter; the distance between the flip-chip LEDs is 100-1000 microns.

6. The method of claim 1, wherein In step S3, a vacuum fast press is used to press the incompletely cured silicone / fluorescent powder composite sheet to the temporary fixing material; the thickness of the silicone / fluorescent powder sheet after pressing is greater than the thickness of the flip-chip LED by more than 30 microns.

7. The method of claim 1, wherein the method further comprises forming a passivation layer on the first and second electrodes. In step S5, the electrode side of the flip-chip LED contacts the encapsulating material sheet; the thickness of the encapsulating material sheet is 30-70 microns; the encapsulating material comprises silicone, epoxy encapsulating material, or glass fiber reinforced PP.

8. The method of claim 1, wherein In step S6, the thickness of the copper foil (5) is 30-200 microns, and the curing temperature is 140-160℃. 9.The method of claim 1, wherein In step S10, the thickness of the covered ink is the same as that of the copper foil.

10. The method of claim 1, wherein In step S11, the plating layer material comprises tin, nickel, gold, or silver.

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