A preparation method of dimmable CSP lamp beads

Abstract

The present invention relates to the field of multi-chip CSP packaging technology, in particular to the field of IPC H01L 25, and more specifically to a method for preparing a dimmable CSP lamp bead. The method comprises the following steps: Step 1: prepare a first silicone film and a second silicone film respectively for standby use, wherein the second silicone film comprises a titanium dioxide silicone film and a silicon dioxide silicone film; Step 2: take a blue light chip and arrange them on a substrate at a fixed interval; Step 3: stick the first silicone film on the surface of the blue light chip; Step 4: stick the titanium dioxide silicone film on the surface of the sample prepared in step 3 of the chip, use a gasket for vacuum pressing, and then polish and grind the surface; Step 5: stick the silicon dioxide silicone film on the surface of the sample prepared in step 4, use a gasket for vacuum pressing; Step 6: solidify the sample prepared in step 5, and obtain the product after cutting. The present invention can realize low-cost multi-chip CSP packaging.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-chip CSP packaging, in particular to the field of IPC H01L 25, and more specifically to a method for preparing a dimmable CSP lamp bead. Background Art

[0002] With the development of science and technology and society, people's demand for color has become clearer. Whether it is urban lighting or consumer electronics atmosphere display, colorful effects are required. Therefore, in order to achieve these needs, the dimming function of lamps is required to adjust the brightness, and also pursue the dimming functions of lamp color temperature and ambient light. The chip-scale packaging (CSP) technology has developed very rapidly and has become a research hotspot in the LED industry at home and abroad. There are two most common solutions in the existing technology: one is to use the three primary colors of red, green and blue (RGB) for color adjustment, and the other is to use the four colors of red, green, blue and white (RGBW) for color adjustment. Although these two solutions can achieve a certain range of dimming and color adjustment, different components need to be used to independently complete the dimming functions of ambient light and color temperature, which usually requires the use of at least 3 light-emitting units with different colors / color temperatures, and the cost is relatively high. There are problems with existing RGB or RGBW packaging: the R red light chip used is 4 times that of the B blue light chip, resulting in high device cost and is not applicable to low-consumption fields; the traditional packaged RGB light-emitting unit is large in size and cannot be applied to ultra-thin 3C products, such as ultra-thin laptop keyboards.

[0003] CN 108922882 A provides a dual-chip CSP packaging structure, which not only has a small packaging structure area, simple manufacturing process and low cost, but also has good heat dissipation performance, long service life and high color gamut level. It includes a heat dissipation substrate and two flip-chip LED chips of different light wave bands, the heat dissipation substrate is a flat structure, and the two flip-chip LED chips are packaged into a CSP chip and welded on the heat dissipation substrate; the two LED chips are coated with a phosphor layer around them to cooperate to excite white light. However, its process is relatively complicated and the cost is relatively high. Summary of the invention

[0004] The present invention provides a method for preparing a dimmable CSP lamp bead, comprising the following steps:

[0005] Step 1: prepare a first silicone film and a second silicone film respectively for standby use, wherein the second silicone film comprises a titanium dioxide silicone film and a silicon dioxide silicone film;

[0006] Step 2: Take the blue light chips and arrange them on the substrate at a fixed interval;

[0007] Step 3: Stick the first silicone film on the surface of the blue light chip;

[0008] Step 4: Stick the titanium dioxide silicone film on the surface of the sample prepared in step 3 of the chip, use a gasket for vacuum pressing, and then polish the surface;

[0009] Step 5: attach the silica silicone film to the surface of the sample prepared in step 4 and perform vacuum pressing using a gasket;

[0010] Step 6: Solidify the sample prepared in step 5 and cut it.

[0011] The first silicone film includes a transparent silicone film, a red silicone film and a green silicone film.

[0012] The raw material for preparing the first silica gel film includes silica gel, and the refractive index of the silica gel is 1.47-1.58.

[0013] Preferably, the raw material for preparing the first silicone film includes silicone, and the refractive index of the silicone is 1.50-1.58.

[0014] This application study found that the use of silicone has better high temperature resistance than traditional epoxy resin. At the same time, CSP can be directly welded to the circuit substrate to increase the heat dissipation area and improve its stability during use. However, since the flatness of the silicone bonding process is difficult to control, the uniformity of the luminous brightness will be affected to a certain extent. This application further found that by adding step 4, the silicone semi-curing process, on the basis of a specific silicone curing process, the problem of brightness uniformity can be effectively solved. It is possible that the semi-curing silicone process combined with the vacuum pressing process provides a better fit.

[0015] The raw materials for preparing the red silica gel film include red phosphor and silica gel, and the amount of the red phosphor is 66-80wt% of the amount of silica gel; the green silica gel film includes yellow-green phosphor and silica gel, and the amount of the yellow-green phosphor is 66-80wt% of the amount of silica gel.

[0016] The wavelength of the red phosphor is 645-655 nm, and the wavelength of the yellow-green phosphor is 515-525 nm.

[0017] The preparation method of the first silicone film comprises: preparing raw materials and mixing them evenly, coating them with a coating machine, and curing them at 140-160° C. for 3.5-4.5 hours to obtain the first silicone film.

[0018] Preferably, the preparation method of the first silicone film comprises: preparing the raw materials by mixing them evenly, coating them with a coating machine, and curing them at 150-160° C. for 3.5-4.5 hours to obtain the first silicone film.

[0019] The thickness of the first silicone film is 150-200 microns.

[0020] Preferably, the thickness of the first silicone film is 150-180 microns.

[0021] The thickness of the titanium dioxide silica gel film is 150-200 microns.

[0022] Preferably, the thickness of the titanium dioxide silica gel film is 180-200 microns.

[0023] The thickness of the silicon dioxide silica gel film is 150-200 microns.

[0024] Preferably, the thickness of the silicon dioxide silica gel film is 180-200 microns.

[0025] The raw materials for preparing the second silica gel film include silica gel and filler, and the amount of the filler is 30-50wt% of the amount of silica gel.

[0026] Preferably, the raw materials for preparing the second silica gel membrane include silica gel and filler, and the amount of the filler is 40-50wt% of the amount of silica gel.

[0027] The preparation method of the second silicone film comprises: mixing the raw materials uniformly, coating, and curing at 70-90° C. for 4-8 minutes to obtain the second silicone film.

[0028] The viscosity of the second silica gel at 25° C. is 150,000-250,000 cps.

[0029] Beneficial effects:

[0030] 1. Compared with the traditional RBG bracket package, the preparation method of the present application has a smaller volume and can be applied to LED lamp beads that provide atmosphere display in ultra-thin electronic devices.

[0031] 2. Compared with the traditional RBG bracket packaging, the green light and red light in the preparation method of the present application are realized by converting the blue light chip, and the overall chip cost is reduced by 50% compared with the traditional red light chip cost.

[0032] 3. The three light-emitting unit chips of the present application can be controlled independently. By adjusting the current, the light-emitting energy of different light colors can be controlled to realize the RGB dimming and color adjustment function.

[0033] 4. This application uses silicone, which has better high temperature resistance than traditional epoxy resin. At the same time, CSP can be directly welded to the circuit substrate to increase the heat dissipation area and improve its stability during use.

[0034] 5. By adding step 4 silicone semi-curing process on the basis of specific silicone curing process, the brightness uniformity can be effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a real picture of the lamp bead in Example 1.

[0036] Figure 2 This is the light-emitting diagram of the lamp bead in Example 1.

[0037] Figure 3 This is the spectrum of Example 1.

[0038] Figure 4 This is a schematic diagram of the lamp bead of comparative example 1.

[0039] Figure 5 This is the spectrum of Comparative Example 1.

[0040] Figure 6 This is a schematic diagram after the completion of step 2 of Example 1, the upper layer is the blue light chip, and the lower layer is the substrate.

[0041] Figure 7 This is a schematic diagram after the completion of step 3 of Example 1, where the top layer is the first silicone film.

[0042] Figure 8 This is a schematic diagram after the vacuum pressing in step 4 of Example 1 is completed. Figure 7 In the added part, the black strip is the titanium dioxide silicone membrane, and the rest is the gasket.

[0043] Fig. 9 This is a schematic diagram after polishing in step 4 of Example 1.

[0044] Fig.10 This is a schematic diagram after the completion of step 5 of Example 1. Fig. 9 In the added part, the black strip is the silicon dioxide silicone membrane, and the rest is the gasket.

[0045] Fig.11 This is a schematic diagram after the completion of step 6 of Example 1. DETAILED DESCRIPTION

[0046] Example 1

[0047] A method for preparing a dimmable CSP lamp bead comprises the following steps:

[0048] Step 1: prepare a first silicone film and a second silicone film respectively for standby use, wherein the second silicone film comprises a titanium dioxide silicone film and a silicon dioxide silicone film;

[0049] Step 2: Take the blue light chip (brand: Sanan 32mil, wavelength range: 440-470nm) and arrange it on the substrate at a pitch of 0.85mm, such as Figure 6 As shown;

[0050] Step 3: Cut the first silicone film into squares with a side length of 1.0 mm using a DISC cutter and stick them on the surface of the blue-ray chip. Figure 7 As shown;

[0051] Step 4: Stick the titanium dioxide silicone film on the surface of the sample prepared in step 3 of the chip, and use a gasket to perform vacuum pressing at 110°C for 6 minutes. Figure 8 As shown, a polishing machine was used to polish at 50 RPM for 2 minutes. Fig. 9 As shown;

[0052] Step 5: Attach the silica gel film to the surface of the sample prepared in step 4, and use a gasket to vacuum press at 110°C for 6 minutes. Fig.10 As shown;

[0053] Step 6: The sample prepared in step 5 is cured and cut to obtain Figure 1 and 2 The lamp bead shown in FIG. 11 is a schematic diagram.

[0054] The first silicone film includes a transparent silicone film, a red silicone film and a green silicone film, and the first silicone film is sequentially attached to the surface of the blue light chip in the order of the red silicone film, the green silicone film and the transparent silicone film.

[0055] The raw material for preparing the transparent silicone film is silicone; the raw materials for preparing the red silicone film are red phosphor (Hilde SDR630Q-S) and silicone, and the amount of the red phosphor is 80wt% of the amount of silicone; the green silicone film includes yellow-green phosphor (Interma KSGL520-18) and silicone, and the amount of the yellow-green phosphor is 66wt% of the amount of silicone.

[0056] The refractive index of the silica gel is 1.54, and the brand is Dow Corning OE6636. This type of silica gel is a two-component silica gel, and when used, it is mixed in a ratio of A:B=1:4.

[0057] The preparation method of the first silicone film includes: preparing raw materials and mixing them evenly (stirring at 1000 RMP for 5 minutes), coating them with a coating machine to a thickness of 150 microns, and curing them at 150° C. for 4 hours to obtain the first silicone film.

[0058] The raw materials for preparing the second silica gel film include silica gel and filler, and the amount of the filler is 30-50wt% of the amount of silica gel.

[0059] The raw materials for preparing the titanium dioxide silica gel film include silica gel and titanium dioxide, the amount of titanium dioxide used is 50wt% of the amount of silica gel used, and the preparation method is: after the raw materials are mixed evenly (stirring at 1000RMP for 5 minutes), they are coated with a coater to a thickness of 200 microns, and cured at 80°C for 5 minutes.

[0060] The raw materials for preparing the silica silica gel film include silica gel and silica, the amount of silica used is 50wt% of the amount of silica gel, and the preparation method is: after the raw materials are mixed evenly (stirring at 1000RMP for 5 minutes), they are coated with a coater to a thickness of 200 microns, and cured at 80°C for 5 minutes.

[0061] Comparative Example 1

[0062] A method for preparing a lamp bead with three primary colors of red, green and blue (RGB), comprising the following steps:

[0063] Step 1: Take 8g of silica gel (the refractive index of the silica gel is 1.54, brand: Dow Corning OE6636, this type of silica gel is a two-component silica gel, and is mixed in a ratio of A:B=1:4 when used) and add SiO2 component material to make a mixed glue, stir it at 1000RMP for 5min, and then use a coating machine to make a silica gel film with a thickness of 200 microns, and cure it at 80℃ for 5min to obtain a mixed light film;

[0064] Step 2: Arrange the 0620mil RGB chips on the adhesive substrate at a fixed pitch;

[0065] Step 3: Place the mixed light film produced in step 1 on top of the chip, put it into a vacuum press with a gasket, and press it at 110°C for 6 minutes.

[0066] Step 4: After pressing, put the product into the oven and bake it at 150℃*4H for curing. Then use the DISC cutting machine to cut it. Figure 4 The lamp beads shown.

[0067] Performance Testing Methods

[0068] The embodiment and comparative example lamp beads were subjected to spectrum testing, such as Figure 3 and Figure 5 shown.

Claims

1. A method for preparing a dimmable CSP lamp bead, characterized in that: The following steps are involved: Step 1: prepare a first silicone film and a second silicone film respectively for standby use, wherein the second silicone film comprises a titanium dioxide silicone film and a silicon dioxide silicone film; Step 2: Take the blue light chips and arrange them on the substrate at a fixed interval; Step 3: Stick the first silicone film on the surface of the blue light chip; Step 4: Stick the titanium dioxide silicone film on the surface of the sample prepared in step 3 of the chip, use a gasket for vacuum pressing, and then polish the surface; Step 5: attach the silica silicone film to the surface of the sample prepared in step 4 and perform vacuum pressing using a gasket; Step 6: solidify the sample prepared in step 5 and cut it; The preparation method of the first silicone film comprises: preparing the raw materials by mixing them evenly, coating them with a coating machine, and curing them at 140-160° C. for 3.5-4.5 hours to obtain the first silicone film; The raw materials for preparing the second silicone film include silicone and filler, and the amount of the filler is 30-50wt% of the amount of silicone. The preparation method of the second silicone film includes: mixing the raw materials evenly, coating them with a coating machine, and curing them at 70-90° C. for 4-8 minutes to obtain; The first silicone film includes a transparent silicone film, a red silicone film and a green silicone film; The raw material for preparing the first silica gel film includes silica gel, and the refractive index of the silica gel is 1.47-1.58; The raw materials for preparing the red silica gel film include red phosphor and silica gel, and the amount of the red phosphor is 66-80wt% of the amount of silica gel; the green silica gel film includes yellow-green phosphor and silica gel, and the amount of the yellow-green phosphor is 66-80wt% of the amount of silica gel; The wavelength of the red phosphor is 645-655nm, and the wavelength of the yellow-green phosphor is 515-525nm; The thickness of the first silicone film is 150-200 microns; The viscosity of the second silica gel at 25° C. is 150,000-250,000 cps.

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