Low-radiative spherical alumina for POP packaging and its manufacturing method

Abstract

This application discloses low-radioactivity spherical alumina for POP packaging and its manufacturing method, which belongs to the packaging material technical field. The alumina particle size distribution has at least two peaks, the uranium content is 5 ppb or less, and the density is 3.6-3.8 g / cm. 3 , Na + and Cl - The content of uranium is 5 ppm or less, and the content of large particles is 100 ppm or less. The manufacturing method involves immersing aluminum-containing raw materials in acid with a pH of 4 or less and reacting them under hydrothermal conditions at 120-180°C to fully dissolve and precipitate the uranium element. The cooled powder is then processed to obtain a sample with a uranium content of less than 5 ppb. The obtained sample is then subjected to a spheroidizing treatment, and the obtained spherical alumina is then refined. Large particles are removed from the refined powder, and the obtained products with different particle sizes are then sorted by particle size to obtain a low-radioactivity spherical alumina product, thereby solving the technical problem of the low stability of existing materials.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to a Chinese patent application filed with the China Patent Office on July 31, 2023, bearing application number CN202310945882.8 and entitled "Low-radiative spherical alumina for POP packaging and its manufacturing method," the entire contents of which are incorporated herein by reference.

[0002] The present application belongs to the technical field of inorganic powders, and in particular to low-radiative spherical alumina for POP packaging and a method for producing the same. [Background technology]

[0003] POP (package on package, or stacked packaging) technology is currently one of the main methods for increasing packaging density. The usual approach is to stack multiple chips to increase packaging density. However, this method leads to an increase in the thickness of the POP fixture, which makes it more difficult to dissipate the heat generated by the semiconductor chip to the outside during operation, posing a major challenge to the stability and reliability of the chip.

[0004] Common solutions tend to achieve heat dissipation through the structural design of the POP package (see Patent Document 1) or by adding a thermal interface material layer to the POP package device (see Patent Document 2), but very few designs take into account the heat dissipation capabilities of the epoxy molding compound (EMC) used in the package.When used in memory chips, the filler in the stacked package or the filler in the thermal interface material layer emits alpha rays due to insufficient management of radioactive elements, which reduces the reliability and stability of the chip during operation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Chinese Patent No. 102522380 [Patent Document 2] Chinese Patent No. 105453255 Summary of the Invention [Problem to be solved by the invention]

[0006] This application provides low-radiation spherical alumina for POP packaging, which improves the heat dissipation of POP packaging, ensures the miniaturization of POP packaging equipment, reduces product thickness, and controls the radioactive elements to reduce the alpha ray content, thereby improving the reliability and stability of memory chip operation. [Means for solving the problem]

[0007] The purpose of this application is to design spherical alumina for use as an EMC material in PO packaging to improve the heat dissipation problem of POP devices. At the same time, the density of spherical alumina is much higher than that of spherical silica powder, a traditional filler, which allows for a certain reduction in the thickness of the POP package.

[0008] The purpose of this application is to design a low-radiation spherical alumina product to avoid "soft errors" caused by the influence of alpha rays during chip operation and improve the reliability and stability of the chip.

[0009] The present application provides low-radioactivity spherical alumina for POP packaging, which has a particle size distribution showing two or more peaks, a uranium content of 5 ppb or less, and a density of 3.6-3.8 g / cm. 3 , Na + and Cl - The ion content is less than 5 ppm, and the large particle content is less than 100 ppm.

[0010] Furthermore, the average particle size of the low-radiative spherical alumina for POP packaging is 5.5 μm or 6 μm.

[0011] The present application also provides a method for producing low-radiative spherical alumina for POP packaging described in the above technical solution, which includes the following steps: Step 1: The aluminum-containing raw material is immersed in an acid with a pH of 4 or less for 8 to 10 hours, and then transferred to a reactor and reacted under hydrothermal conditions at 120 to 180°C for 2 to 8 hours to fully dissolve and precipitate uranium. The hydrothermal reaction process involves partial crystal phase transformation, which relatively increases the gaps between the crystal grains, making it easier for uranium impurities to dissolve. A surfactant such as hexane or polyethylene glycol can also be added to the acid solution used to reduce the surface tension of the solution. The aluminum-containing raw material includes alumina, aluminum hydroxide, or boehmite, and has a uranium content of 5 to 50 ppb and a particle size of 20 to 80 μm.

[0012] Step 2: The cooled powder from Step 1 is filtered with suction, and the filtered sample is added to a ball mill jar and pulverized to the particle size required for spheroidization using zirconia as the grinding medium. The pulverized sample is in a slurry state, and the sample is filtered with suction again, washing the sample repeatedly with deionized water during the suction filtration process. The filtered sample is then dried with hot air at 105-200°C to obtain a sample with a uranium content of less than 5 ppb.

[0013] Step 3: The sample obtained in Step 2, which has a uranium content of less than 5 ppb, is placed in a spheroidizing device and subjected to spheroidizing treatment at a high temperature of 2100°C or higher to obtain spherical alumina with a sphericity of more than 0.90.

[0014] Step 4: The spherical alumina obtained in step 3 is purified, and the purification is carried out under acidic conditions or in pure water to obtain a purified powder, wherein the content of uranium element is less than 5 ppb, and Na + and Cl - The ion content is 5 ppm or less.

[0015] Step 5: The refined powder is subjected to removal of large particles, the selected method including air classification, wet screening, or flotation, and the content of large particles in the product after removal is less than 100 ppm.

[0016] Step 6: The products with different particle sizes obtained in Step 5 are sorted by particle size to obtain the low-radioactivity spherical alumina for POP packaging.

[0017] The present application further provides an epoxy molding compound (EMC / Epoxy Molding Compound), which includes an epoxy resin and low-emissivity spherical alumina for POP packaging; The low-radioactivity spherical alumina for POP packaging is the low-radioactivity spherical alumina for POP packaging described in the above technical solution or the low-radioactivity spherical alumina for POP packaging manufactured by the manufacturing method described in the above technical solution.

[0018] Furthermore, the filling rate of the low-emissivity spherical alumina for POP packaging in the epoxy molding compound is 85%.

[0019] Furthermore, the epoxy molding compound has a thermal conductivity of 2.8W or 2.9W and a density of 3.20g / cm 3 or 3.21 g / cm 3 The alpha ray content is 0.002 count / cm 2 Less than ·h. [Effects of the Invention]

[0020] This application has the following advantages: Compared with the spherical silicon oxide and low-radiative spherical silicon oxide commonly used in POP packaging, the target product described in this application has obvious advantages in thermal conductivity and density. When used in POP packaging, it not only improves the heat dissipation problem of the POP device, but also reduces the thickness of the POP device and reduces the alpha ray content, thereby ensuring the reliability and stability of the chip during operation. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a particle size diagram of the low-radiative spherical alumina of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0022] [Example 1] Uranium element content ≦5ppb, Na + and Cl - Content ≦ 5ppm, density 3.7g / cm 3 A low-emission spherical alumina product with a large particle content of ≦100 ppm, a particle size distribution consisting of two peaks, and an average particle size of 6 μm was mixed with epoxy resin at a filling rate of 85% to produce an EMC. The resulting EMC had a thermal conductivity of 2.8 W and a density of 3.21 g / cm. 3 and the alpha ray content is <0.002 count / cm 2 ·h.

[0023] [Example 2] Uranium element content ≦5ppb, Na + and Cl - Content ≦ 5ppm, density 3.67g / cm 3 A low-emission spherical alumina product with a large particle content of ≦100 ppm, a three-peak particle size distribution, and an average particle size of 5.5 μm was mixed with epoxy resin at a filling rate of 85% to produce an EMC. The resulting EMC had a thermal conductivity of 2.9 W and a density of 3.20 g / cm. 3 and the alpha ray content is <0.002 count / cm 2 ·h.

[0024] [Example 3] Uranium element content ≦1ppb, Na + and Cl - Content ≦ 5ppm, density 3.67g / cm 3 A low-emission spherical alumina product with a large particle content of ≦100 ppm, a three-peak particle size distribution, and an average particle size of 5.5 μm was mixed with epoxy resin at a filling rate of 85% to produce an EMC. The resulting EMC had a thermal conductivity of 2.9 W and a density of 3.20 g / cm.3 and the alpha ray content is <0.001 count / cm 2 ·h.

[0025] [Comparative Example 1] The uranium element content is about 15 ppb, and Na + and Cl - Content ≦ 5 ppm, density 2.20 g / cm 3 The spherical silicon oxide product, with a large particle content of ≦100 ppm, a particle size distribution consisting of three peaks, and an average particle size of 5.5 μm, was mixed with epoxy resin at a filling rate of 85% to produce an EMC. The resulting EMC had a thermal conductivity of 0.6 W and a density of 2.13 g / cm. 3 The alpha ray content is approximately 0.008 count / cm 2 ·h.

[0026] Comparative Example 2 Uranium element content ≦1ppb, Na + and Cl - Content ≦ 5 ppm, density 2.20 g / cm 3 A low-emission spherical silicon oxide product with a large particle content of ≦100 ppm, a three-peak particle size distribution, and an average particle size of 5.5 μm was mixed with epoxy resin at a filling rate of 85% to produce an EMC. The resulting EMC had a thermal conductivity of 0.6 W and a density of 2.11 g / cm. 3 and alpha ray content is less than 0.001 count / cm 2 ·h.

[0027] Comparative Example 3 The uranium element content is about 200 ppb, and Na + and Cl - Content ≦ 5ppm, density 3.67g / cm 3 A typical spherical alumina product with a large particle content of ≦100 ppm, a three-peak particle size distribution, and an average particle size of 5.5 μm was mixed with epoxy resin at an 85% filling rate to produce an EMC. The resulting EMC had a thermal conductivity of 2.9 W and a density of 3.20 g / cm. 3 However, the alpha ray content was already 0.01 count / cm 2 It exceeded ·h.

[0028] Test results show that compared with the spherical silicon oxide and low-radiation spherical silicon oxide commonly used in POP packaging, the target product described in this application has obvious advantages in thermal conductivity and density. When used in POP packaging, it can not only improve the heat dissipation problem of the POP device, but also reduce the thickness of the POP device and reduce the alpha ray content, thereby ensuring the reliability and stability of the chip operation.

[0029] The above examples have comprehensively described the present application, but they are only a part of the present application and are not all examples. Other examples can be obtained based on these examples without any creative assumptions, and all of these examples fall within the scope of protection of the present application.

Claims

1. The alumina particle size distribution has at least two peaks, the uranium content is 5 ppb or less, and the density is 3.6 to 3.8 g / cm ３ , Na ＋ and Cl － 1. A low-radioactivity spherical alumina for POP packaging, characterized in that the content of 5 ppm or less of fluorine-containing compounds and the content of large particles are 100 ppm or less.

2. 2. The low-radioactivity spherical alumina for POP packaging according to claim 1, wherein the average particle size of the low-radioactivity spherical alumina for POP packaging is 5.5 μm or 6 μm.

3. Step 1: immersing an aluminum-containing raw material in an acid solution having a pH of 4 or less for 8 to 10 hours, transferring the aluminum-containing raw material to a reactor, and reacting the aluminum-containing raw material under hydrothermal conditions at 120 to 180°C for 2 to 8 hours to sufficiently dissolve and precipitate uranium, so that the uranium content in the aluminum-containing raw material is 5 to 50 ppb and the particle size is 20 to 80 μm; Step 2: The cooled powder in step 1 is filtered by suction, the filtered sample is added to a ball mill jar, and the sample is pulverized to a particle size required for spheroidization. The pulverized sample is in a slurry state. The sample is filtered by suction again, and the sample is repeatedly washed with deionized water during the suction filtration process. The filtered sample is dried by hot air at 105°C to 200°C to obtain a sample with a uranium content of less than 5 ppb. Step 3: placing the sample having a uranium content of less than 5 ppb obtained in step 2 into a spheroidizing device and subjecting it to spheroidizing treatment at a high temperature of 2100°C or higher to obtain spherical alumina having a sphericity of more than 0.90; The spherical alumina obtained in step 3 is purified, and the purification is carried out under acidic conditions or in pure water to obtain a purified powder, wherein the content of uranium element is less than 5 ppb, and Na ＋ and Cl － Step 4, in which the content of ions is 5 ppm or less; Step 5: removing coarse particles from the refined powder, so that the content of large particles in the product after the removal is 100 ppm or less; 3. A method for producing low-radioactivity spherical alumina for POP packaging according to claim 1 or 2, characterized in that it includes a step 6 of sorting the products of different particle sizes obtained in step 5 by particle size to obtain the low-radioactivity spherical alumina for POP packaging.

4. 4. The method according to claim 3, wherein a surfactant is added to the acid solution in step 1 to reduce the surface tension of the solution.

5. 5. The method according to claim 4, wherein the surfactant is n-hexane or polyethylene glycol.

6. 4. The method of claim 3, wherein the method used to remove large particles in step 5 is air classification, wet screening, or flotation.

7. 4. The method according to claim 3, wherein the aluminum-containing raw material in step 1 is alumina, aluminum hydroxide, aluminum powder, or boehmite.

8. 4. The method according to claim 3, wherein zirconia is used as the grinding medium in step 2.

9. Contains epoxy resin and low-emission spherical alumina for POP packaging, An epoxy molding compound, characterized in that the low-radioactivity spherical alumina for POP packaging is the low-radioactivity spherical alumina for POP packaging described in claim 1 or 2, or the low-radioactivity spherical alumina for POP packaging manufactured by the manufacturing method described in claims 3 to 8.

10. 10. The epoxy molding compound according to claim 9, wherein the filling rate of the low-emissivity spherical alumina for POP packaging in the epoxy molding compound is 85%.

11. The epoxy molding compound has a thermal conductivity of 2.8W or 2.9W and a density of 3.20g / cm ３ or 3.21 g / cm ３ The alpha ray content is 0.002 count / cm ２ Epoxy molding compound according to claim 9 or 10, characterized in that it has a viscosity of less than h.

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