Preparation method and application of chip box dam glue

Abstract

The invention discloses a preparation method and application of chip box dam glue. The preparation method comprises the following steps: taking raw materials of the chip box dam glue, and carrying out centrifugal stirring; the chip box dam glue is prepared from the following raw materials in percentage by weight: 70 to 74 percent of inorganic filler, 13 to 16 percent of epoxy resin, 12 to 15 percent of curing agent, 0.1 to 0.4 percent of solid modified imidazole latent accelerant and 0 to 0.2 percent of pigment, wherein the epoxy resin comprises liquid bisphenol A epoxy resin and / or liquid alicyclic epoxy resin; the technological parameters of centrifugal stirring are as follows: the rotation speed is 1500 r / min to 3000 r / min, the revolution speed is 1000 r / min to 1800 r / min, and the stirring time is 100 s to 200 s. According to the prepared chip box dam glue, the room temperature viscosity is 270-430 Pa.s, the thixotropic value can reach 4.8-6.6, the viscosity is proper, the thixotropic property is remarkably improved, and the chip box dam glue can be applied to a box dam filling process of a chip.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor chip packaging technology, and specifically relates to a method for preparing a chip dam glue and its application. Background Art

[0002] Dam glue, also known as weir glue, can be used in the dam-fill process. This process requires both dam glue (DAM glue) and fill glue. Dam glue is first used to form a weir around the chip. The weir acts as a physical barrier, isolating the chip and gold wires from the outside environment and protecting them. Fill glue is then used to pot the area enclosed by the weir to encapsulate the chip. The dam-fill process requires precise control over the flow and shape of the dam glue. Therefore, a thixotropic dam glue is required. It flows quickly to form the weir during dispensing and then quickly sets after dispensing, forming a reliable physical barrier. Summary of the Invention

[0003] One of the purposes of the present application is to provide a method for preparing a chip dam glue, comprising: taking various raw materials of the chip dam glue and centrifugally stirring them; The raw materials of the chip dam glue include: 70-74 wt.% inorganic filler, 13-16 wt.% epoxy resin, 12-15 wt.% curing agent, 0.1-0.4 wt.% solid modified imidazole latent accelerator, and 0-0.2 wt.% pigment; wherein the epoxy resin includes liquid bisphenol A epoxy resin and / or liquid alicyclic epoxy resin; The process parameters of the above centrifugal stirring are: rotation speed 1500r / min-3000r / min, revolution speed 1000r / min-1800r / min, stirring time 100s-200s.

[0004] In some embodiments, the preparation method further comprises: dispersing the mixture after centrifugal stirring. A three-roller dispersion method can be used, and the dispersion process parameters are: the feed gap and the discharge gap of the three rollers are 200um-250um and 100um-150um respectively.

[0005] Furthermore, the preparation method further comprises: vacuum degassing the dispersed mixture. A centrifugal mixer can be used for vacuum degassing. The process parameters for vacuum degassing are: rotation speed of 2500 r / min, revolution speed of 800 r / min, and vacuum degassing time of 100 s.

[0006] In some embodiments, the solid modified imidazole latent accelerator may be HMA-2300, JTN-30 or PN-23.

[0007] In some embodiments, the inorganic filler is preferably silica with a particle size of 25 μm to 75 μm.

[0008] In some embodiments, the curing agent is an organic acid anhydride curing agent or an amine curing agent. Further, the curing agent can be selected from methylnadic anhydride, benzoic anhydride or m-phenylenediamine.

[0009] The second purpose of this application is to provide an application of the above chip dam glue in the chip dam filling process.

[0010] In this application, the solid-state modified imidazole latent promoter can be adsorbed on the surface of the inorganic filler particles, occupying the active sites on the surface of the inorganic filler particles. Through the steric hindrance effect, it hinders the inorganic filler particles from approaching each other, prevents the inorganic filler from agglomerating, maintains the stability of the inorganic filler dispersion, and thus improves the thixotropic properties. The epoxy resin and the inorganic filler particles are bonded through hydrogen bonds and / or van der Waals forces. The high shear force of centrifugal stirring cuts off the bond between the epoxy resin and the inorganic filler particles, releasing more active sites on the surface of the inorganic filler particles to bind to the solid-state modified imidazole latent promoter, further enhancing the steric hindrance effect, and thus further improving the thixotropic properties.

[0011] Compared with the prior art, this application has the following advantages and beneficial effects: The room temperature viscosity of the chip dam glue prepared in the present application is 270-430 Pa.s, and the thixotropic value can reach 4.8-6.6. The viscosity is appropriate and the thixotropic performance is significantly improved. DETAILED DESCRIPTION

[0012] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0013] The preparation method of the chip dam glue provided in the embodiment of the present application includes: taking the raw materials of the chip dam glue and centrifugally stirring them; the raw materials of the above-mentioned chip dam glue include: 70-74wt.% of inorganic filler, 13-16wt.% of epoxy resin, 12-15wt.% of curing agent, 0.1-0.4wt.% of solid modified imidazole latent accelerator, and 0-0.2wt.% of pigment; wherein, the epoxy resin includes liquid bisphenol A epoxy resin and / or liquid alicyclic epoxy resin; the process parameters of the above-mentioned centrifugal stirring are: rotation speed 1500r / min-3000r / min, revolution speed 1000r / min-1800r / min, and stirring time 100s-200s.

[0014] In some embodiments, the centrifugally stirred mixture is further dispersed using three rollers, and the dispersion process parameters may be as follows: the feed gap and the discharge gap of the three rollers are 200um-250um and 100um-150um, respectively.

[0015] Furthermore, the method further includes: vacuum degassing the dispersed mixture. A centrifugal mixer can be used for vacuum degassing. The process parameters of the vacuum degassing are: rotation speed of 2500 r / min, revolution speed of 800 r / min, and vacuum degassing time of 100 s.

[0016] In this application, inorganic fillers are primarily used to reduce the internal stress and thermal expansion coefficient of the dam adhesive. Conventional inorganic fillers such as silica can be used. In some embodiments, the inorganic filler is silica, preferably with a particle size of 25 μm to 75 μm. A larger particle size helps increase the filling ratio of the inorganic filler, thereby increasing the modulus and glass transition temperature (Tg) of the dam adhesive.

[0017] In the present application, an epoxy resin serves as the resin matrix, a curing agent is used to initiate a curing reaction with the epoxy resin at a specific temperature, and an accelerator is used to accelerate the curing reaction. In some embodiments, the epoxy resin is preferably a liquid bisphenol A epoxy resin or a liquid alicyclic epoxy resin, for example, DER336 liquid bisphenol A epoxy resin, ERL-4221 liquid alicyclic epoxy resin, or S-06E liquid alicyclic epoxy resin.

[0018] The curing agent can be selected from the curing agents disclosed in the prior art and compatible with the epoxy resin. In some embodiments, the curing agent can be an organic acid anhydride curing agent or an amine curing agent, such as nadic anhydride, benzoic anhydride, or m-phenylenediamine. In some embodiments, the solid modified imidazole latent accelerator can be selected from HMA-2300, JTN-30, or PN-23.

[0019] The chip dam glue prepared above can be applied to the chip dam filling process to form a cofferdam structure around the chip.

[0020] In this application, the thixotropic properties of the dam glue are significantly improved by combining a solid-state modified imidazole latent accelerator with centrifugal stirring. The imidazole ring nitrogen atom in the solid-state modified imidazole latent accelerator has strong polarity and can be adsorbed on the surface of the inorganic filler particles through van der Waals force and / or electrostatic force, forming a "protective film" on the surface of the inorganic filler particles, reducing direct contact between the inorganic filler particles and preventing agglomeration. Because the solid-state modified imidazole latent accelerator adsorbed on the surface of the inorganic filler particles occupies the active sites on the surface of the inorganic filler particles, it can hinder other inorganic filler particles from approaching, maintain the stability of the inorganic filler dispersion, and thus help to improve the thixotropic properties of the dam glue.

[0021] The surface of the inorganic filler particles also bonds to the epoxy resin through hydrogen bonds and / or van der Waals forces. Under the high shear of centrifugal stirring, the polymer chains of the epoxy resin move violently, generating frictional heat, local temperature increases, and the polymer chains disentangle, breaking the bond between the inorganic filler and the epoxy resin. The solid-state modified imidazole latent accelerator can occupy more active sites on the surface of the inorganic filler particles, further enhancing the steric hindrance effect and the thixotropic properties of the dam adhesive. After the centrifugal stirring stops, the thermal motion of the polymer chains weakens, and the structure destroyed by shear is gradually rebuilt. This reconstruction process consumes energy, resulting in additional thermal effects inside and outside the system and local temperature increases. This structural reconstruction reduces the free volume, and intermolecular forces such as hydrogen bonds and van der Waals forces regain dominance, increasing viscosity and enhancing thixotropy.

[0022] Generally speaking, the greater the shear force or the longer the shear duration, the more active sites the solid-state modified imidazole latent accelerator occupies, the greater the steric hindrance effect, and the better the thixotropic properties of the dam adhesive. When the solid-state modified imidazole latent accelerator is completely and evenly adsorbed on the surface of the inorganic filler particles, the steric hindrance effect no longer increases, and the thixotropic properties reach their peak. Further increasing the amount of solid-state modified imidazole latent accelerator can further enhance the thixotropic properties until all active sites on the inorganic filler particle surface are once again fully occupied.

[0023] To further illustrate the present application, the following examples and comparative examples are provided. The raw materials used in the examples and comparative examples are as follows: Inorganic filler: commercially available silica, particle size range 25um-75um; Epoxy resin: liquid bisphenol A epoxy resin, brand: DER336, viscosity at 25°C: 11000mPa·s-15000mPa·s, epoxy value: 0.51eq / 100g-0.54eq / 100g; Curing agent: methyl nadic anhydride; Solid modified imidazole latent accelerator: HMA-2300; Carbon black: commercially available.

[0024] Example 1 The raw materials and mass percentages of the chip dam glue in this embodiment are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; HMA-2300 0.25%; The centrifugal stirring parameters are: rotation 2200 r / min, revolution 1400 r / min, and centrifugal stirring time 150 s.

[0025] Example 2 The raw materials and mass percentages of the chip dam glue in this embodiment are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; HMA-2300 0.25%; The centrifugal stirring parameters are: rotation 3000 r / min, revolution 1800 r / min, and centrifugal stirring time 200 s.

[0026] Example 3 The raw materials and mass percentages of the chip dam glue in this embodiment are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; HMA-2300 0.25%; The centrifugal stirring parameters are: rotation 1500 r / min, revolution 1000 r / min, and centrifugal stirring time 100 s.

[0027] Example 4 The raw materials and mass percentages of the chip dam glue in this embodiment are as follows: Silicon dioxide 72.85%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; HMA-2300 0.4%; The centrifugal stirring parameters are: rotation 2200 r / min, revolution 1400 r / min, and centrifugal stirring time 150 s.

[0028] Example 5 The raw materials and mass percentages of the chip dam glue in this embodiment are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.2%; Carbon black 0.2%; HMA-2300 0.1%; The centrifugal stirring parameters are: rotation 2200 r / min, revolution 1400 r / min, and centrifugal stirring time 150 s.

[0029] Comparative Example 1 The raw materials of the chip dam glue in this comparative example and the mass percentages of the raw materials are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; Diethyltetramethylimidazole 0.25%; The centrifugal stirring parameters are: rotation 2200 r / min, revolution 1400 r / min, and centrifugal stirring time 150 s.

[0030] Comparative Example 2 The raw materials of the chip dam glue in this comparative example and the mass percentages of the raw materials are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; N,N-dimethylbenzylamine 0.25%; The centrifugal stirring parameters are: rotation 2200 r / min, revolution 1400 r / min, and centrifugal stirring time 150 s.

[0031] Comparative Example 3 The raw materials of the chip dam glue in this comparative example and the mass percentages of the raw materials are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; HMA-2300 0.25%; The centrifugal stirring parameters are: rotation 3500 r / min, revolution 2300 r / min, and centrifugal stirring time 250 s.

[0032] Comparative Example 4 The raw materials of the chip dam glue in this comparative example and the mass percentages of the raw materials are as follows: Silicon dioxide 73%; DER336 14.5%; Methyl nadic anhydride 12.05%; Carbon black 0.2%; HMA-2300 0.25%; The centrifugal stirring parameters are: rotation 1000 r / min, revolution 700 r / min, and centrifugal stirring time 80 s.

[0033] The chip dam glue samples of the above examples and comparative examples were prepared by the following method: (1) Take the raw materials of chip dam glue and use a centrifugal mixer to centrifuge: (2) Use three rollers to disperse the mixture after centrifugal stirring, and the feed gap and discharge gap of the three rollers are 200 μm and 100 μm respectively; (3) The dispersed mixture was vacuum degassed using a centrifugal mixer. The process parameters for vacuum degassed were: rotation speed 2500 r / min, revolution speed 800 r / min, and vacuum degassed time 100 s.

[0034] The performance parameters of the chip dam glue samples of the embodiment and the comparative example were tested in the following manner: 1. Viscosity: Use a rotational viscometer to measure the viscosity of the sample at 25°C and a rotation speed of 5 rpm; 2. Thixotropic value: Use a rotational viscometer to measure the viscosity values ​​P1 and P2 at 25°C, 5 rpm and 50 rpm respectively. P1 / P2 is the thixotropic value. 3. Premix temperature: Use an infrared temperature gun to measure the temperature of the colloid when centrifugal stirring is completed.

[0035] Table 1 Performance parameters of dam glue samples in Examples and Comparative Examples The test data are listed in Table 1. It can be seen from Table 1 that the thixotropic values ​​of Examples 1-5 of the present application can reach 4.8-6.6, and the thixotropic performance is significantly improved. In the chip dam filling process, when the dam glue viscosity exceeds 450 Pa.s, the glue will not be discharged smoothly during dispensing, so the dam glue viscosity should not exceed 450 Pa.s. The viscosity of Examples 1-5 of the present application is appropriate.

[0036] Comparing Example 1 with Comparative Examples 1-2, the only difference is the accelerator. The accelerator in Example 1 is a solid modified imidazole latent accelerator HMA-2300, the accelerator in Comparative Example 1 is a liquid imidazole accelerator, and the accelerator in Comparative Example 2 is a liquid tertiary amine accelerator. Compared with Example 1, the thixotropic value of Comparative Examples 1-2 is only 1.0-1.2, and the thixotropic performance is far inferior to that of Example 1.

[0037] Comparing Examples 1-3 with Comparative Example 3, the only difference lies in the centrifugal stirring process parameters. In Comparative Example 3, the rotational and orbital speeds of the centrifugal agitator were too high, and the centrifugal stirring time was too long. Although the thixotropic value of Comparative Example 3 increased somewhat, the viscosity also increased significantly, significantly exceeding 450 Pa.s. The inventors believe that this may be due to the excessive rotational and orbital speeds and prolonged centrifugal stirring, which significantly heats the colloid. As can be seen from the premix temperature in Comparative Example 3, which reached 80°C, some of the epoxy resin may have begun to undergo a curing reaction, leading to the significant increase in viscosity.

[0038] Comparing Examples 1-3 and Comparative Example 4, the only difference lies in the centrifugal stirring process parameters. In Comparative Example 4, the rotation and revolution speeds of the centrifugal stirring are lower, and the centrifugal stirring time is shorter. While the thixotropic value of Comparative Example 4 improves relative to Comparative Examples 1-2, it is still significantly lower than that of Examples 1-5. The inventors believe that this may be due to the lower colloid temperature when the rotation and revolution speeds of the centrifugal stirring are lower, and the shorter the centrifugal stirring time, the incomplete destruction of hydrogen bonds and / or van der Waals forces between the epoxy resin and the inorganic filler particles. The solid-state modified imidazole latent accelerator fails to occupy more active sites on the surface of the inorganic filler particles, resulting in a limited steric hindrance effect and a failure to significantly improve the thixotropic properties.

[0039] The above embodiments are merely for the purpose of illustrating the embodiments and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications may be made based on the above descriptions. It is not necessary and impossible to enumerate all implementation methods here. Therefore, any obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for preparing a chip dam glue, characterized in that: include: Taking the raw materials of chip dam glue and centrifugally stirring them; The raw materials of the chip dam glue include: 70-74 wt.% of inorganic filler, 13-16 wt.% of epoxy resin, 12-15 wt.% of curing agent, 0.1-0.4 wt.% of solid modified imidazole latent accelerator, and 0-0.2 wt.% of pigment; wherein the epoxy resin includes liquid bisphenol A epoxy resin and / or liquid alicyclic epoxy resin; The process parameters of the centrifugal stirring are: rotation 1500r / min-3000r / min, revolution 1000r / min-1800r / min, and stirring time 100s-200s.

2. The method for preparing the chip dam glue according to claim 1, wherein: Also includes: The centrifugally stirred mixture is dispersed.

3. The method for preparing the chip dam glue according to claim 2, wherein: Also includes: The dispersed mixture was vacuum degassed.

4. The method for preparing a chip dam glue according to claim 1, wherein: The solid modified imidazole latent accelerator is selected from HMA-2300, JTN-30 or PN-23.

5. The method for preparing the chip dam glue according to claim 1, wherein: The inorganic filler is silicon dioxide with a particle size of 25um-75um.

6. The method for preparing a chip dam glue according to claim 1, wherein: The curing agent is an organic anhydride curing agent or an amine curing agent.

7. The method for preparing the chip dam glue according to claim 6, wherein: The curing agent is selected from methylnadic anhydride, benzoic anhydride or m-phenylenediamine.

8. Use of the chip dam adhesive prepared by the preparation method according to any one of claims 1 to 7 in a chip dam filling process.

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