A method for preparing high-purity molten silicon powder for IC packaging

Abstract

The present invention relates to the field of silicon powder processing technology, specifically a method for preparing high-purity molten silicon micropowder for IC packaging, and the specific processing technology is as follows: (1) taking raw sodium silicate and placing it in a high-pressure tank with a filter screen inside, mixing and dissolving at high temperature and high pressure, and then tilting the high-pressure tank to allow the undissolved sodium silicate to pass through the filter screen and separate from the solution to obtain material A; (2) quantitatively adding hydrochloric acid to the material A obtained in step (1) to fully react until the material A is completely dissolved to obtain product A, and then heating and concentrating the product A to precipitate silicon dioxide gel; (3) calcining and crushing to obtain. After experiments, the silicon micropowder prepared by the method of the present invention has a silicon dioxide purity of more than 99.99%, which has extremely high market competitiveness as a plastic packaging filler. At the same time, it solves the problem of difficulty and high cost of removing Na ions in the traditional process of preparing silicon micropowder by neutralizing sodium silicate with acid, which is of great significance to the development of enterprises.

Description

Technical Field

[0001] The invention relates to the technical field of silicon powder processing, in particular to a method for preparing high-purity molten silicon micropowder for IC packaging. Background Art

[0002] IC packaging refers to connecting the circuit pins on the silicon chip to the external connector with wires so as to connect with other devices. It not only plays the role of installing, fixing, sealing, protecting the chip and enhancing the electrical and thermal performance, but also connects the contacts on the chip to the pins of the package shell with wires. These pins are connected to other devices through wires on the printed circuit board, thereby realizing the connection between the internal chip and the external circuit. Because the chip must be isolated from the outside world, impurities in the air should not corrode the chip circuit and cause a decline in electrical performance.

[0003] In the prior art, high-purity fused silicon powder for IC packaging is usually prepared by a sol-gel method using alkoxysilane to make a gel, which is then crushed and fired to obtain a finished product. However, this method has high requirements on raw materials and is relatively costly. Summary of the invention

[0004] In order to solve the problems raised in the above background technology, the present invention provides a method for preparing high-purity molten silicon powder for IC packaging.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing high-purity molten silicon powder for IC packaging, the specific processing technology is as follows:

[0007] (1) Raw material pretreatment

[0008] The raw material sodium silicate is placed in a high-pressure tank with a filter inside, added into deionized water and mixed and dissolved for 30 to 40 minutes at 100 to 110° C. and 130 to 150 kPa, and then the undissolved sodium silicate is separated from the solution through the filter by tilting the high-pressure tank to obtain material A; the sodium silicate with a low modulus inside the sodium silicate is removed by high-temperature and high-pressure dissolution, so as to reduce the content of Na ions in the raw material, reduce the cost of removing Na ion impurities, and improve the purity of the subsequent silicon micropowder product;

[0009] (2) Acid neutralization treatment

[0010] Add 2 to 3 times the mass fraction of hydrochloric acid to the material A obtained in step (1) to fully react until the material A is completely dissolved to obtain product A, then heat the product A at 90 to 95° C. and concentrate it to 32.5% to 41.8% of the original mass, and filter out the precipitated colloid to obtain silica gel; by controlling the ratio of material A to hydrochloric acid, material A can be fully reacted with hydrochloric acid, and the product A obtained by the reaction is a mixed solution of sodium chloride and silicic acid, and then by controlling the different solubility of sodium chloride at different temperatures and the temperature and the concentration ratio of product A, the silicic acid solution in product A is supersaturated to precipitate silica gel, while sodium chloride is not precipitated, thereby achieving the technical effect of removing Na ion impurities;

[0011] (3) Firing and crushing

[0012] The silicon dioxide gel is fired, dried and then crushed to obtain high-purity molten silicon powder for IC packaging.

[0013] Furthermore, in step (1), the raw material pretreatment is preferably to place the raw material sodium silicate in a high-pressure tank with a filter screen inside, add it into deionized water and mix and dissolve it at 105° C. and 140 kPa for 35 minutes.

[0014] Furthermore, the preferred mass ratio of material A to hydrochloric acid in step (2) is 1:2.5.

[0015] Furthermore, the product A in step (2) is preferably concentrated by heating at 92° C. to 35.5% of the original mass.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. Remove the sodium silicate with low modulus inside the sodium silicate by high temperature and high pressure dissolution, and only retain the sodium silicate with high modulus. Start purification from the raw materials, which is convenient for reducing the content of Na ions in the raw materials, reducing the cost of removing Na ion impurities, and improving the purity of subsequent silicon micropowder products;

[0018] 2. By controlling the ratio of material A to hydrochloric acid, material A can be fully reacted with hydrochloric acid. The product A obtained by the reaction is a mixed solution of sodium chloride and silicic acid. Then, by controlling the solubility of sodium chloride at different temperatures and the temperature and the concentration ratio of product A, the silicic acid solution in product A is supersaturated to precipitate silica gel, while sodium chloride is not precipitated, thereby achieving the technical effect of removing Na ion impurities. DETAILED DESCRIPTION Example 1

[0019] A method for preparing high-purity molten silicon powder for IC packaging, the specific processing technology is as follows:

[0020] (1) Raw material pretreatment

[0021] The raw material sodium silicate is placed in a high-pressure tank with a filter inside, added into deionized water and mixed and dissolved at 100°C and 130 kPa for 30 minutes, and then the high-pressure tank is tilted to allow the undissolved sodium silicate to pass through the filter and be separated from the solution to obtain material A;

[0022] (2) Acid neutralization treatment

[0023] Adding hydrochloric acid twice the mass fraction of the material A obtained in step (1) to the material A for full reaction until the material A is completely dissolved to obtain product A, then heating the product A at 90° C. to concentrate it to 32.5% of the original mass, and filtering out the precipitated colloid to obtain silica gel;

[0024] (3) Firing and crushing

[0025] The silicon dioxide gel is fired, dried and then crushed to obtain high-purity molten silicon powder for IC packaging. Example 2

[0026] (1) Raw material pretreatment

[0027] The raw material sodium silicate is placed in a high-pressure tank with a filter inside, added into deionized water and mixed and dissolved at 110°C and 150 kPa for 40 minutes, and then the high-pressure tank is tilted to allow the undissolved sodium silicate to pass through the filter and be separated from the solution to obtain material A;

[0028] (2) Acid neutralization treatment

[0029] Add 2 to 3 times the mass fraction of hydrochloric acid to the material A obtained in step (1) to react fully until the material A is completely dissolved to obtain product A, then heat the product A at 95° C. and concentrate it to 41.8% of the original mass, and filter out the precipitated colloid to obtain silica gel;

[0030] (3) Firing and crushing

[0031] The silicon dioxide gel is fired, dried and then crushed to obtain high-purity molten silicon powder for IC packaging. Example 3

[0032] (1) Raw material pretreatment

[0033] The raw material sodium silicate is placed in a high-pressure tank with a filter inside, added to deionized water and mixed and dissolved at 105°C and 140 kPa for 35 minutes, and then the high-pressure tank is tilted to allow the undissolved sodium silicate to pass through the filter and separate from the solution to obtain material A;

[0034] (2) Acid neutralization treatment

[0035] Add 2.5 times the mass fraction of hydrochloric acid to the material A obtained in step (1) to react fully until the material A is completely dissolved to obtain product A, then heat the product A at 92° C. and concentrate it to 35.5% of the original mass, and filter out the precipitated colloid to obtain silica gel;

[0036] (3) Firing and crushing

[0037] The silicon dioxide gel is fired, dried and then crushed to obtain high-purity molten silicon powder for IC packaging.

[0038] Comparative Example 1

[0039] Compared with Example 1, the difference between this comparative example and step 1 is that the operation described in step (1) is not performed, and the purchased high modulus sodium silicate is directly cleaned and then the operations of steps (2) and (3) are performed.

[0040] Comparative Example 2

[0041] The difference between this comparative example and Example 2 is that the quantitative operation described in step (2) is not performed, but sufficient hydrochloric acid is added to fully react and dissolve material A, and then heated and dried until product A is precipitated.

[0042] Control group

[0043] The existing process of preparing silicon micropowder by neutralizing sodium silicate with acid.

[0044] The silicon micropowders obtained by the above six processes were sampled and tested for composition. The results are as follows:

[0045]

[0046] After sampling and testing the components of the silicon micropowders produced by the above six processes, it can be seen that the silicon micropowder produced by the method of the present invention has a silicon dioxide purity of more than 99.99%, and has extremely high market competitiveness as a plastic packaging filler. At the same time, it solves the problem of difficulty and high cost in removing Na ions in the traditional process of preparing silicon micropowder by acid neutralization of sodium silicate, which is of great significance to the development of enterprises.

[0047] The above two experiments verify that the silicon micropowder processed by the present invention can effectively improve the hydrophobic performance after being mixed into the copper clad plate resin, and at the same time, temporarily add magnetism to the silicon micropowder, thereby improving its fluidity after being mixed into the resin. After demagnetization is completed, its hydrophobic performance will not be affected, and it has strong practicality.

[0048] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. In addition, it should be understood that although this specification is described in accordance with the implementation methods, not each implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing high-purity molten silicon powder for IC packaging, characterized in that: The specific processing technology is as follows: (1) Raw material pretreatment The raw material sodium silicate is placed in a high-pressure tank with a filter inside, added into deionized water and mixed and dissolved for 30-40 minutes at 100-110°C and 130-150 kPa, and then the high-pressure tank is tilted to allow the undissolved sodium silicate to pass through the filter and be separated from the solution to obtain material A; (2) Acid neutralization treatment Add 2 to 3 times the mass fraction of hydrochloric acid to the material A obtained in step (1) to react fully until the material A is completely dissolved to obtain product A, then heat the product A at 90 to 95° C. and concentrate it to 32.5% to 41.8% of the original mass, and filter out the precipitated colloid to obtain silica gel; (3) Firing and crushing The silicon dioxide gel is fired, dried and then crushed to obtain high-purity molten silicon powder for IC packaging.

2. The method for preparing high-purity molten silicon powder for IC packaging according to claim 1, characterized in that: The raw material pretreatment in step (1) is to place the raw material sodium silicate in a high-pressure tank with a filter screen inside, add it into deionized water and mix and dissolve it at 105° C. and 140 kPa for 35 minutes.

3. The method for preparing high-purity molten silicon powder for IC packaging according to claim 1, characterized in that: The mass ratio of material A to hydrochloric acid in step (2) is 1:2.

5.

4. The method for preparing high-purity molten silicon powder for IC packaging according to claim 1, characterized in that: The product A in step (2) is heated at 92° C. and concentrated to 35.5% of the original mass.

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