A method for protecting a liquid on a warped LED chip

Abstract

The application discloses a kind of warping LED chip protection liquid method, in turn is chip front face film, back cutting, chip overturn, protection liquid drop, protective film covers, vacuum adsorption and centrifugal rotation.Combining the warping characteristics of the existing grinding method to the LED chip, by chip front face film, reduce the risk of chip fragment, chip back cutting releases grinding stress to reduce chip warping, protective film covers can guarantee that all areas of warping LED chip are wrapped with protection liquid, centrifugal rotation makes the protection liquid of LED chip surface everywhere uniform, forms tight and uniform protective layer on the surface of LED chip, plays the role of isolation heat and metal debris when laser cutting, achieves the effect that chip surface circuit is not oxidized and chip is not broken edge, after laser cutting, clean up metal debris and residual protective layer completely.

Description

Technical Field

[0001] This invention relates to the technical field of LED chips, and more specifically to a method for warping a protective liquid on an LED chip. Background Technology

[0002] To meet the demands of semiconductor technology development, wafer sizes have gradually increased from 4 inches to 12 inches. However, after thinning, the required thickness is less than 160µm or even 150µm. Due to the characteristics of wafers, the grinding and thinning process cannot maintain their flatness. Current grinding and thinning processes are essentially a physical loss process involving wheel extrusion, contact grinding, wafer breakage, and particle removal. As the grinding wheel descends, the silicon wafer is subjected to extrusion. During grinding, the contact between the wheel and the chip surface, along with the high-speed rotation and descent of the wheel, gradually removes surface material, reducing chip thickness. However, this physical grinding and thinning method inevitably damages the wafer, and uneven stress on the chip surface during grinding can cause LED chip warping. Laser cutting's high efficiency dictates the cutting method for LED chips, but the large amount of heat and metal debris generated during laser cutting can affect LED chip performance. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for applying a protective liquid to a warped LED chip. Before laser cutting of the LED chip, the protective liquid is uniformly applied by vacuum adsorption and centrifugal rotation to form a protective layer, thereby achieving the purpose of isolating heat and metal debris.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for warping a protective liquid on an LED chip includes the following steps:

[0006] 1) Apply a film to the front side of the pre-made warped LED chip;

[0007] 2) Perform back-side cutting on warped LED chips that have already been coated with film. Back-side cutting can reduce the degree of LED chip warping by releasing stress.

[0008] 3) Flip the warped LED chip that has been cut on the back so that the front side of the chip is facing up, then place it on a flat pad and drop a protective liquid into the center of the chip.

[0009] 4) Cover the front of the warped LED chip with the protective liquid, and then press the protective film from the inside until the protective liquid completely covers the warped LED chip.

[0010] 5) Remove the protective film from the surface of the warped LED chip, vacuum adsorb the warped LED chip first, then centrifuge and rotate it, and after taking it out, you will get the warped LED chip with protective liquid.

[0011] Furthermore, in step 1), the warped LED chip is a Si chip with a concave front and a warping degree of 8-15mm on the left and right sides, and a thickness of 150-160μm.

[0012] Furthermore, in step 1), the film coating on the front side of the warped LED chip is done using a matching film coating machine.

[0013] Furthermore, in step 2), the equipment used for back-side cutting is an ultraviolet laser cutting machine with a power of 15-20 kW, a wavelength of 300-400 nm, a cutting speed of 50-300 mm / s, a back-side cutting depth of 50-60 μm, and an in-slice cutting depth deviation controlled within ±3 μm.

[0014] Furthermore, in step 3), a film-coating machine is used to flip the warped LED chip that has been cut on the back side.

[0015] Furthermore, in step 3), the flat pad is an antistatic adhesive pad.

[0016] Furthermore, in step 3), a dropper is used to draw up the protective solution and place it in the center of the chip to drip down. The amount of protective solution used for a single chip is 3 to 5 ml.

[0017] Further, in step 4), the protective film is a frosted PET film. After covering the front of the warped LED chip with the PET film, a cotton ball is used to press the PET film evenly in a spiral motion from the inside out until the protective liquid completely covers the warped LED chip.

[0018] Furthermore, in step 5), a two-fluid cleaning machine is selected for vacuum adsorption and centrifugal rotation, with a rotation speed of 500-3000 r / min and a time of 20-150 s.

[0019] Furthermore, the protective liquid includes propylene glycol methyl ether, which can form a protective layer on the surface of the LED chip. The heat and metal debris generated during the laser cutting process will be blocked outside the protective layer. After laser cutting, cleaning can remove the metal debris and residual protective layer, thus achieving the purpose of isolating heat and metal debris.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The method for applying a protective liquid to a warped LED chip according to the present invention comprises, in sequence, applying a film to the front side of the chip, cutting the back side, flipping the chip, dripping the protective liquid, covering with a protective film, vacuum adsorption, and centrifugal rotation. Combining the warping characteristics of LED chips caused by existing grinding methods, applying a film to the front side of the chip reduces the risk of chip breakage; cutting the back side of the chip releases grinding stress and reduces chip warping; covering with a protective film ensures that all areas of the warped LED chip are coated with protective liquid; and the combination of vacuum adsorption and centrifugal rotation ensures uniform protective liquid distribution across the LED chip surface, thereby forming a tight and uniform protective layer on the LED chip surface. Without a protective layer, the heat and metal debris generated during laser cutting can cause oxidation of the chip surface circuitry and chipping. The tight and uniform protective layer isolates heat and metal debris, achieving the effect of no oxidation of the chip surface circuitry and no chipping. After laser cutting, cleaning thoroughly removes the metal debris and residual protective layer. Compared to other methods of uniformly coating protective liquid, this method can achieve full coverage of warped LED chips, achieve more uniform coating, and use less protective liquid (only 3-5ml). It not only ensures uniform coating of protective liquid, but also reduces costs.

[0022] (2) In the method of the present invention, a two-fluid cleaning machine is specifically selected to perform vacuum adsorption and centrifugal rotation on the warped LED chip. This method can achieve full coverage of the warped LED chip, the coating is more uniform, and the amount of protective liquid used is less. It not only ensures uniform coating of the protective liquid, but also reduces costs.

[0023] (3) Because the warp characteristics of LED chips make the back-side film easily break, the warped LED chips are coated on the front side. Considering the concave nature of the front side of the warped LED chip, coating on the front side avoids breakage and reduces chip loss. The back side laser cutting releases the surface stress generated during the thinning and grinding process, reducing the warp of the LED chip. Attached Figure Description

[0024] Figure 1 This is a sample image of a warped LED chip from Example 1;

[0025] Figure 2 This is a sample image of a warped LED chip with a back side laser-cut shape, as shown in Example 1.

[0026] Figure 3 This is a droplet image of the protective liquid for the warped LED chip sample in Example 1;

[0027] Figure 4 This is a protective liquid coverage diagram of the warped LED chip sample from Example 1.

[0028] Figure 5 This is a centrifugal rotation diagram of the warped LED chip sample from Example 1. Detailed Implementation

[0029] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0030] Example 1

[0031] A method for warping a protective liquid on an LED chip includes the following steps:

[0032] 1) As Figure 1 The warped LED chip shown is coated on the front side using a matching coating machine; wherein, the warped LED chip is a Si chip with a concave front side, a warping degree of 8-15mm on the left and right sides, and a thickness of 150-160μm.

[0033] 2) The warped LED chip with the film already applied is back-side cut to obtain, as shown in the figure. Figure 2 The warped LED chip shown is an ultraviolet laser cutter with a power of 15kw, a wavelength of 355nm, a cutting speed of no more than 300mm / s, a back-side cutting depth controlled at 50-60μm, and an in-chip cutting depth deviation controlled at ±3μm.

[0034] 3) Use a film-coating machine to flip the warped LED chips that have been cut on the back side so that the front side of the chip is facing up, and then place them on an anti-static pad, such as... Figure 3 As shown, a protective solution is dropped into the center of the chip; the protective solution is GMAX-U03c-7719, and the amount of protective solution used per chip is 4ml.

[0035] 4) such as Figure 4 As shown, a protective film is placed on the front of the warped LED chip that has been coated with protective liquid. Then, a cotton ball is used to press the PET film evenly in a spiral motion from the inside out until the protective liquid completely covers the warped LED chip. The protective film is a frosted PET film with a size of 150mm x 150mm and a thickness of 60μm. The frosted side has low adhesion and is elastic.

[0036] 5) Peel off the PET film from the surface of the warped LED chip, such as... Figure 5 As shown, the warped LED chip was first vacuum-adsorbed in a two-fluid cleaning machine, then centrifuged, and after removal, a warped LED chip coated with a protective solution was obtained. The rotation speed was 2500 r / min, and the time was 100 s.

[0037] Comparative Example 1

[0038] The method of applying protective liquid to the warped LED chip in Comparative Example 1 differs from that in Example 1 in that the type and amount of protective liquid used in Comparative Example 1 are the same as those in Example 1, and the protective liquid in Comparative Example 1 is sprayed evenly onto the surface of the warped LED chip.

[0039] Performance testing

[0040] The warped LED chips processed in Example 1 and Comparative Example 1 were laser-cut. After cutting, the oxidation of the circuits on the chip surface and whether there was any edge chipping were observed, as shown in Table 1.

[0041] Table 1 shows the condition of the warped LED chips after laser cutting in Example 1 and Comparative Example 1.

[0042]

[0043]

[0044] As shown in Table 1, the treatment method of Example 1 can form a uniform protective layer on the surface of the warped LED chip. This protective layer can uniformly absorb the laser energy and act on the chip surface, preventing edge chipping caused by cutting the chip at high temperatures, and also preventing the metal lines on the chip surface from being oxidized at high temperatures. Comparative Example 1, spraying the same amount of protective liquid as in Example 1, could not uniformly cover the warped LED chip, resulting in poor protective performance.

[0045] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for warping a protective liquid on an LED chip, characterized in that, Includes the following steps: 1) Apply a film to the front side of the pre-made warped LED chip; 2) Perform back-side cutting on the warped LED chips that have already been coated with film; 3) Flip the warped LED chip that has been cut on the back so that the front side of the chip is facing up, then place it on a flat pad and drop a protective liquid into the center of the chip. 4) Cover the front of the warped LED chip with the protective liquid, and then press the protective film from the inside until the protective liquid completely covers the warped LED chip. 5) Remove the protective film from the surface of the warped LED chip, vacuum adsorb the warped LED chip first, then centrifuge and rotate it, and after taking it out, you will get the warped LED chip with protective liquid.

2. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 1), the warped LED chip is a Si chip with a concave front and a warping degree of 8-15mm on the left and right sides, and a thickness of 150-160μm.

3. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 1), the film is applied to the front side of the warped LED chip using a matching film application machine.

4. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 2), the equipment used for back-side cutting is an ultraviolet laser cutting machine with a power of 15-20kw, a wavelength of 300-400nm, a cutting speed of 50-300mm / s, a back-side cutting depth of 50-60μm, and an in-slice cutting depth deviation controlled within ±3μm.

5. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 3), the warped LED chip that has been cut on the back side is flipped using a film-coating machine.

6. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 3), the flat pad is an antistatic adhesive pad.

7. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 3), use a dropper to draw up the protective solution and place it in the center of the chip to drip down. The amount of protective solution used for a single chip is 3 to 5 ml.

8. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 4), the protective film is a frosted PET film. After covering the front of the warped LED chip with the PET film, use a cotton ball to press the PET film evenly in a spiral motion from the inside out until the protective liquid completely covers the warped LED chip.

9. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, In step 5), a two-fluid cleaning machine is used for vacuum adsorption and centrifugal rotation at a speed of 500-3000 r / min for 20-150 s.

10. The method for applying a protective liquid to a warped LED chip as described in claim 1, characterized in that, The protective liquid includes propylene glycol methyl ether.

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