A heat-resistant and anti-glue cracking chip-level packaged LED and its preparation method

Abstract

The present invention provides a heat-resistant and anti-glue crack chip-level packaged LED and a preparation method thereof, belonging to the technical field of semiconductor devices. The chip-level packaged LED comprises a chip, and a glue layer covering the four sides and the top of the chip; the glue layer comprises glass fiber, phosphor and silica gel, and the silica gel is a mixture of a chain-type vinyl silicone resin and a mesh vinyl silicone resin containing an organic magnesium group. The preparation method comprises: arranging the chips on a substrate at intervals; mixing the phosphor and silica gel, adding glass fiber, and mixing evenly to obtain a packaging glue; covering the four sides and the top of the chip with the packaging glue by coating or plastic sealing, baking and curing to form a glue layer; and splitting into single chip-level packaged LEDs. The present invention coats the four sides and the top of the chip with a modified packaging glue layer containing phosphor, and by adding an organic magnesium group to the silica gel structure of the modified packaging glue layer, the problem of the glue layer in the prior art being prone to cracking and failure under high temperature and high humidity use is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor devices, and particularly relates to a heat-resistant and anti-glue crack chip-level packaged LED and a preparation method thereof. Background Art

[0002] LED (light emitting diode) is widely used in lighting, backlight, display and other fields due to its unique optoelectronic properties and ultra-long life. Under the premise of protecting the chip, the LED package must also be able to transmit light, so the LED package has special requirements for the packaging materials and structure. In addition, as the power of LED becomes larger and the size becomes smaller, the high temperature places higher and higher requirements on LED packaging. Among them, chip-scale packaged LED (CSP-LED for short) breaks through the limitations of traditional devices on packaging size, and has the characteristics of high optical density, no gold wire, no bracket, no solid crystal glue, low thermal resistance, etc., and has the advantages of high efficiency, reliability, low cost and designability; but CSP-LED also has technical obstacles in terms of temperature resistance and deformation resistance.

[0003] When preparing CSP-LED, a mixture of encapsulation glue and phosphor is used as the encapsulation material. Currently, the most common encapsulation glues are epoxy encapsulation glues and silicone encapsulation glues. Among them, vinyl silicone resin encapsulation glues have the advantages of high light transmittance, UV resistance, and good aging resistance, and are widely used in CSP-LED packaging. The basic structural formula of vinyl silicone resin is: However, CSP-LED products encapsulated with conventional vinyl silicone encapsulation glue cannot meet the use requirements under high temperature (such as the pad foot temperature TS is as high as 150°C); CSP-LED has a small heat dissipation area due to its small size, and the high temperature generated by the chip under current state cannot be effectively dissipated. At the same time, because the encapsulation material is a mixture of phosphor and colloid, there is a difference in the expansion coefficient of the colloid and the chip at high temperature, which will cause a series of problems such as cracking of the glue, a significant reduction in transparency and light output efficiency, and thus lead to the failure of CSP-LED. Summary of the invention

[0004] In view of this, the present invention aims to provide a heat-resistant and anti-glue crack chip-level packaged LED and a preparation method thereof, aiming to solve at least one technical problem in the background technology.

[0005] The present invention is achieved in that:

[0006] The first aspect of the present invention provides a heat-resistant and anti-glue crack chip-level packaged LED, comprising:

[0007] chip;

[0008] A glue layer covering the periphery and top of the chip;

[0009] The adhesive layer includes glass fiber, fluorescent powder and silica gel, and the silica gel is a mixture of chain-type vinyl silicone resin and mesh-type vinyl silicone resin;

[0010] The structural formula of the chain-type vinyl silicone resin is as follows (1):

[0011] (1);

[0012] The structural formula of the reticular vinyl silicone resin is as follows (2):

[0013] (2);

[0014] In formula (1) and formula (2), n is the number of repeating units of the bifunctional chain segment, m is the number of repeating units of the tetrafunctional chain segment; R' and R'' are each independently or methyl, and at least one of R` and R`` is , x is 1 or 2; R 1 C 4 Alkyl~C 10 Alkyl; R 2 C 2 Alkenyl~C 8 Alkenyl; R 3 for , y is an integer from 1 to 6; Mg is the atom connected to the corresponding silicon chain.

[0015] Preferably, the weight ratio of the chain-type vinyl silicone resin monomer to the network-type vinyl silicone resin monomer is 1:1-1.1, and the structural formula of the chain-type vinyl silicone resin monomer is: ; The structural formula of the reticular vinyl silicone resin monomer is: .

[0016] Preferably, according to the molar ratio, in the silica gel The group is 0.9% to 1.2% of the difunctional chain segment and the tetrafunctional chain segment.

[0017] Preferably, the amount of glass fiber is 30wt%~40wt% of the silica gel.

[0018] Preferably, the length of the glass fiber is 15um~35um and the width is 5um~15um.

[0019] A second aspect of the present invention provides a method for preparing a heat-resistant and anti-glue crack chip-scale packaged LED, comprising the following steps:

[0020] Arranging the chips at intervals on the substrate;

[0021] The phosphor and silica gel are mixed evenly according to a preset ratio, and then glass fiber is added and mixed evenly to obtain a packaging glue;

[0022] The encapsulation glue is applied to cover the periphery and top of the chip by coating or plastic sealing, and then baked and cured to form an adhesive layer; the chip is then split into individual chip-level packaged LEDs.

[0023] Preferably, the phosphor comprises yellow phosphor and red phosphor, and the weight ratio of yellow phosphor: red phosphor: silica gel is 60-120:8-20:30-150.

[0024] Preferably, the thickness of the glue layer covering the periphery of the chip is 100um-140um; the thickness of the glue layer covering the top of the chip is 80um-120um.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention coats the chip with a modified encapsulation adhesive layer containing phosphor around and on the top, and solves the problem of the adhesive layer in the prior art being prone to cracking and failure under high temperature and high humidity by adding an organic magnesium group to the silica gel structure of the modified encapsulation adhesive layer.

[0027] 2. The present invention uses vinyl silicone resin as the basic silicone and regulates the groups on the silicone chain, such as phenyl, methyl and other organic groups, so as to achieve changes in the strength and hardness of the silicone; an organic magnesium group is set on the side chain, so that the product can withstand higher temperatures and increase the product's usage strength.

[0028] 3. The adhesive layer of the present invention uses a mixture of chain-type silicone resin and mesh silicone resin containing organic magnesium groups as a steel skeleton structure and glass fiber as a sand and gravel filler to form a concrete-like structure, thereby significantly enhancing the toughness and strength of the adhesive layer of the phosphor and withstanding higher temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The actual pictures are of the conventional vinyl silicone resin adhesive layer and the adhesive layer of Example 1 of the present invention after being tested for 2000 hours under high temperature and high humidity environment;

[0030] Figure 2 This is an electron microscope scanning image of the packaging glue in Example 1 of the present invention;

[0031] Figure 3 This is a physical picture of the adhesive layer after curing in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] A heat-resistant and anti-glue crack chip-level packaged LED, comprising: a chip, and a glue layer covering the periphery and top of the chip;

[0034] In a specific implementation, the adhesive layer includes glass fiber, phosphor and silica gel, and the silica gel is a mixture of chain-type vinyl silicone resin and mesh-type vinyl silicone resin;

[0035] The structural formulas of the chain-type vinyl silicone resin and the network-type vinyl silicone resin are respectively as follows:

[0036] (1); (2);

[0037] In formula (1) and formula (2), n is the number of repeating units of the bifunctional chain segment, m is the number of repeating units of the tetrafunctional chain segment; R' and R'' are each independently or methyl, and at least one of R` and R`` is , i.e., an organic magnesium group, x is 1 or 2; R 1 C 4 Alkyl~C 10 Alkyl; R 2 C 2 Alkenyl~C 8 Alkenyl; R 3 for , y is an integer from 1 to 6; Mg is an atom connected to the corresponding silicon chain;

[0038] In the following examples, x=1, R 1 Select butane; R 2 Select Vinyl, R 3 Where y=1; but not limited to the listed functional groups, other functional groups not listed are also applicable;

[0039] In the present invention, a mixture of chain-type vinyl silicone resin and mesh vinyl silicone resin containing organic magnesium groups is used as a steel skeleton structure, and glass fiber is used as a sand and gravel filler to form a glue layer of a concrete structure, thereby significantly enhancing the toughness and strength of the phosphor glue layer and withstanding higher temperatures.

[0040] The present invention uses vinyl silicone resin as the basic silicone and regulates the groups on the silicone chain (such as phenyl, methyl and other organic groups) to achieve changes in the strength and hardness of the silicone; organic magnesium groups are added to the silicone structure to make the product withstand higher temperatures and increase the product's use strength;

[0041] In a specific implementation, the addition ratio of the organic magnesium group is 0.9% to 1.2%; the ratio refers to the molar ratio of the organic magnesium group to the corresponding functional chain segment in the chain-type vinyl silicone resin and the network vinyl silicone resin; in the chain-type vinyl silicone resin, the functional chain segment is a difunctional chain segment of the D structure; in the network vinyl silicone resin, the functional chain segment is a tetrafunctional chain segment of the Q structure; the addition ratio of the organic magnesium group can be 0.9%, 1.0%, 1.1%, 1.2%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0042] When preparing silica gel, the corresponding monomers are subjected to hydrolysis polymerization to generate the corresponding vinyl silicone resin. To ensure the strength and toughness of silica gel, during preparation, the monomers of chain-type vinyl silicone resin and the monomers of network-type vinyl silicone resin are used in a ratio of about 1:1 to 1.1, which is a weight ratio, for example, 1:1, 1:1.1, but not limited to the listed values, and other values ​​not listed in the numerical range are also applicable;

[0043] The monomer structure formula of chain-type vinyl silicone resin is: ;

[0044] The monomer structure formula of the reticular vinyl silicone resin is: .

[0045] The adjustment of the above-mentioned addition ratio of the organic magnesium group and the monomer ratio can be achieved by adjusting the addition amount of the monomer and the compound corresponding to the organic magnesium group when preparing the corresponding vinyl silicone resin.

[0046] In a specific implementation, the amount of glass fiber used is 30wt%-40wt% of the silica gel; for example, it can be 30wt% or 40wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; the length of the glass fiber is 15um~35um, and the width is 5um~15um; the glass fiber is used as an additive to further enhance the strength of the chip-level packaging LED packaging products.

[0047] The chip-scale packaging LED packaging process is as follows:

[0048] (1) Arrange the chips on the substrate at intervals;

[0049] (2) Mixing the phosphor and silica gel evenly according to a preset ratio, adding glass fiber, and mixing evenly to obtain a packaging adhesive; the phosphor includes yellow phosphor and red phosphor, and the weight ratio of yellow phosphor: red phosphor: silica gel is 60~120:8~20:30~150;

[0050] (3) Cover the chip with encapsulation glue around and on the top by coating or plastic sealing, and bake at high temperature to solidify it to form an adhesive layer; split it into individual chip-level packaged LEDs; the thickness of the adhesive layer covering the chip around is 100um~140um, preferably 120um; the thickness of the adhesive layer covering the top of the chip is 80um~120um, preferably 100um.

[0051] Example 1

[0052] A method for preparing a heat-resistant and anti-glue crack chip-level packaged LED comprises the following steps:

[0053] (1) Arrange the chips on the substrate at intervals;

[0054] (2) Mixing yellow phosphor: red phosphor: silica gel at a ratio of 90:15:100, adding glass fiber at a weight ratio of 30% of the weight of silica gel, and mixing evenly to obtain encapsulation adhesive; the weight ratio of monomers of chain-type vinyl silicone resin to monomers of network vinyl silicone resin in silica gel is 1:1, and the molar ratio of organic magnesium group to corresponding functional segments in chain-type vinyl silicone resin and network vinyl silicone resin is 0.9%;

[0055] (3) Cover the chip with encapsulation glue around and on the top by coating, and then bake at high temperature to solidify it to form a glue layer; then split it into individual chip-scale packaged LEDs (i.e. CSP-LEDs); the thickness of the glue layer covering the chip around is 120um; the thickness of the glue layer covering the top of the chip is 100um.

[0056] The heat resistance and anti-glue cracking performance of chip-scale packaged LEDs were tested under high temperature (150°C) and high humidity (90% humidity) environments.

[0057] Figure 1 The actual pictures are of the conventional vinyl silicone resin adhesive layer and the adhesive layer of Example 1 of the present invention after being tested for 2000 hours under high temperature and high humidity environment; Figure 1 In the embodiment, A is a CSP-LED adhesive layer made of conventional vinyl silicone resin as a silicone rubber, and B is a CSP-LED adhesive layer made in Example 1; Figure 1 It can be seen that the heat resistance and anti-crack performance of the adhesive layer of Example 1 are much better than those of the conventional vinyl silicone resin adhesive layer.

[0058] The electron microscope scanning image of the encapsulation glue in Example 1 of the present invention is as follows: Figure 2 As shown, Figure 2 The numbers marked in the figure are the length and width of the glass fiber, in um. Figure 2 It can be seen that after adding glass fiber, obvious refraction and reflection appear at the interface.

[0059] The actual picture of the glue layer after curing in Example 1 of the present invention is as follows Figure 3 As shown, Figure 3The linear substance in the middle is glass fiber.

[0060] Example 2

[0061] The difference between Example 2 and Example 1 is that the molar ratio of the organic magnesium group to the corresponding functional chain segments in the chain-type vinyl silicone resin and the network vinyl silicone resin is adjusted, and other parameters are consistent with Example 1. This Example 2 is used to study the effects of different addition ratios of the organic magnesium group on the heat resistance and anti-gel cracking properties of chip-scale packaged LEDs. The parameters and performance comparisons are shown in Table 1.

[0062] Table 1

[0063]

[0064] It can be seen from the data in Table 1 that as the proportion of organic magnesium groups increases, the time that the chip-level packaged LED remains intact and free of gel cracks in a high temperature and high humidity environment increases, indicating that its heat resistance and gel crack resistance gradually enhances; but when the proportion exceeds a certain value, the heat resistance and gel crack resistance gradually decrease and the brightness decreases, so the molar proportion of organic magnesium groups is set to 0.9% to 1.2%.

[0065] Example 3

[0066] The difference between this embodiment 3 and embodiment 1 is that the weight ratio of the monomer of the chain-type vinyl silicone resin to the monomer of the network vinyl silicone resin in the silica gel is adjusted, and other parameters are consistent with embodiment 1. This embodiment 3 is used to study the influence of different weight ratios (expressed as D:Q) of the monomer of the chain-type vinyl silicone resin (abbreviated as D) and the monomer of the network vinyl silicone resin (abbreviated as Q) in the silica gel on the heat resistance and anti-glue cracking performance of chip-level packaged LED. The parameters and performance comparison are shown in Table 2.

[0067] Table 2

[0068]

[0069] It can be seen from the data in Table 2 that as the weight ratio of the monomer of the chain-type vinyl silicone resin to the monomer of the network vinyl silicone resin decreases, the time that the chip-scale packaged LED remains intact without glue cracking in a high temperature and high humidity environment increases, indicating that its heat resistance and glue cracking resistance gradually enhances; but when the ratio is lower than a certain value, the heat resistance and glue cracking resistance gradually decreases, so D:Q is set to 1:1~1.1.

[0070] Example 4

[0071] The difference between Example 4 and Example 1 is that the amount of glass fiber is adjusted, and other parameters are consistent with Example 1. Example 4 is used to study the influence of different amounts of glass fiber on the heat resistance and anti-glue cracking performance of chip-level packaged LEDs. The parameters and performance comparison are shown in Table 3.

[0072] Table 3

[0073]

[0074] It can be seen from the data in Table 3 that as the amount of glass fiber increases, the time that the chip-level packaged LED remains intact without glue cracking in a high temperature and high humidity environment increases, indicating that its heat resistance and glue cracking resistance gradually enhances; but when the amount exceeds a certain value, the heat resistance and glue cracking resistance gradually decreases, so the amount of glass fiber is set to 30wt%~40wt% of the silica gel.

[0075] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A heat-resistant and anti-glue crack chip-level packaged LED, characterized in that: include: chip; A glue layer covering the periphery and top of the chip; The adhesive layer includes glass fiber, fluorescent powder and silica gel, and the silica gel is a mixture of chain-type vinyl silicone resin and mesh-type vinyl silicone resin; The structural formula of the chain-type vinyl silicone resin is as follows (1): （1）； The structural formula of the reticular vinyl silicone resin is as follows (2): （2）； In formula (1) and formula (2), n is the number of repeating units of the bifunctional chain segment, m is the number of repeating units of the tetrafunctional chain segment; R' and R'' are each independently or methyl, and at least one of R` and R`` is , x is 1 or 2; R1 is C4 alkyl~C 10 Alkyl; R2 is C2 alkenyl to C8 alkenyl; R3 is , y is an integer from 1 to 6; Mg is an atom connected to the corresponding silicon chain; According to the weight ratio, the usage ratio of the chain-type vinyl silicone resin monomer and the network-type vinyl silicone resin monomer is 1:1~1.1, and the structural formula of the chain-type vinyl silicone resin monomer is: ; The structural formula of the reticular vinyl silicone monomer is: ; According to the molar ratio, in the silica gel The group is 0.9% to 1.2% of the difunctional chain segment and the tetrafunctional chain segment; The amount of the glass fiber is 30wt% to 40wt% of the silica gel.

2. The heat-resistant and anti-glue crack chip-scale packaged LED according to claim 1, characterized in that: The length of the glass fiber is 15um-35um, and the width is 5um-15um.

3. The method for preparing a heat-resistant and anti-glue crack chip-scale packaged LED according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: Arranging the chips at intervals on the substrate; The phosphor and silica gel are mixed evenly according to a preset ratio, and then glass fiber is added and mixed evenly to obtain a packaging glue; Covering the surroundings and top of the chip with the encapsulation glue by coating or plastic packaging, and baking and curing to form a glue layer; Divide into individual chip-scale packaged LEDs.

4. The method for preparing a heat-resistant and anti-glue crack chip-scale packaged LED according to claim 3, characterized in that: The phosphor powder includes yellow phosphor powder and red phosphor powder, and the weight ratio of yellow phosphor powder: red phosphor powder: silica gel is 60~120:8~20:30~150.

5. The method for preparing a heat-resistant and anti-glue crack chip-scale packaged LED according to claim 3, characterized in that: The thickness of the glue layer covering the chip is 100um~140um; the thickness of the glue layer covering the top of the chip is 80um~120um.

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