A phenyl silicone elastomer for high-power semiconductor device packaging and its preparation method

Abstract

The present invention belongs to the technical field of packaging insulating materials for high-power semiconductor devices, and discloses a phenyl silicone elastomer for packaging high-power semiconductor devices and a preparation method thereof; the preparation method is: in a protective gas atmosphere, in toluene, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane are used as raw materials and polymerized under the catalysis of tetramethylammonium hydroxide to obtain methylphenyl polysiloxane; the copolymerization product of dimethyl-terminated vinyl silicone oil and methylphenyl polysiloxane is mixed with an inhibitor, methylphenyl side chain hydrogen-containing silicone oil and methylphenyl end hydrogen-containing silicone oil, and then cross-linked under the catalysis of a platinum catalyst to form a phenyl silicone elastomer for packaging high-power semiconductor devices. The phenyl silicone elastomer prepared by the present invention has a breakdown voltage of up to 66kv / mm under a DC electric field, a maximum withstand voltage of up to 71kv / mm, a temperature resistance of up to 250°C, can work in a 200°C environment for a long time, and can meet the packaging requirements of new high-power semiconductor devices.

Description

Technical Field

[0001] The invention relates to the technical field of packaging insulating materials for high-power semiconductor devices, and in particular to a phenyl silicon elastomer for packaging high-power semiconductor devices and a preparation method thereof. Background Art

[0002] High-voltage, high-power semiconductor devices are important core components of modern industry and play an important role in new power systems, electrified transportation and other fields.

[0003] The existing technology takes into account that dimethyl silicone elastomer materials have good electrical insulation properties, and after curing, they have elasticity and viscosity, as well as good flame retardancy and chemical corrosion resistance, and can provide support for internal stress balance and bonding of devices. Therefore, dimethyl silicone elastomer materials have become the main packaging insulation materials for semiconductor devices.

[0004] However, with the advancement of wide bandgap semiconductor silicon carbide, gallium nitride and other material technologies, power semiconductor devices are developing towards higher voltage levels and higher operating temperatures. The photoconductive switch developed based on silicon carbide materials can reach a rise time of 2.05ns and a pulse voltage of 74.5kv. In addition, new high-power semiconductor devices such as silicon carbide semiconductor devices can reach an operating temperature of 300°C when fully utilized, and high-temperature environments will aggravate the aging of device packaging. Existing dimethyl silicone elastomers are difficult to meet the high-voltage and high-temperature resistance requirements of new high-power semiconductor devices for packaging insulation materials. Therefore, it is necessary to demand new packaging insulation materials for high-power semiconductor devices to meet actual usage requirements.

[0005] To this end, the present invention provides a phenyl silicone elastomer for high-power semiconductor device packaging and a preparation method thereof. Summary of the invention

[0006] In order to solve the deficiencies in the above-mentioned prior art, the present invention provides a phenyl silicone elastomer for high-power semiconductor device packaging and a preparation method thereof. In order to improve the high-voltage and high-temperature resistance of the packaging insulation material, the present invention introduces a large-volume phenyl group on the basis of the traditional dimethyl silicone elastomer, increases the steric hindrance of the polysiloxane, and the π-π interaction between the introduced phenyl groups also effectively enhances the intermolecular force, thereby significantly improving the internal rotation resistance of the silicone elastomer molecular chain, effectively suppressing the vibration phenomenon caused by the movement of the chain segments, and enhancing its ability to withstand high voltage, so that the phenyl silicone elastomer prepared by the present invention has a strong tolerance in terms of molecular vibration, charge behavior and bubble discharge, thereby greatly improving the electrical and temperature resistance of the elastomer material, which can better meet the packaging requirements of new high-power semiconductor devices, provide help for the development of semiconductor devices, and have important significance for the progress of high-power semiconductor devices and the development of new power systems.

[0007] The phenyl silicone elastomer for high-power semiconductor device packaging and the preparation method thereof of the present invention are realized by the following technical scheme:

[0008] The first object of the present invention is to provide a method for preparing a phenyl silicone elastomer for high-power semiconductor device packaging, comprising the following steps:

[0009] Step 1, preparation of methylphenyl vinyl-terminated polysiloxane:

[0010] In a protective gas atmosphere, toluene is used as a solvent, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane are used as raw materials, and a polymerization reaction is carried out under the catalysis of tetramethylammonium hydroxide to obtain methylphenyl polysiloxane; dimethyl vinyl-terminated silicone oil is used as a capping agent, and the methylphenyl polysiloxane is copolymerized to obtain methylphenyl vinyl-terminated polysiloxane.

[0011] Step 2, cross-linking to form a phenyl silicone elastomer for high-power semiconductor device packaging:

[0012] The methylphenyl-terminated vinyl polysiloxane is mixed with an inhibitor, methylphenyl side-chain hydrogen-containing silicone oil and methylphenyl-terminated hydrogen-containing silicone oil to obtain a mixture; under the catalytic action of a platinum catalyst, the mixture is stirred to react so that the components are cross-linked, and the mixture is cured after vacuum evacuation to obtain the phenyl silicone elastomer for high-power semiconductor device packaging.

[0013] Wherein, the viscosity of the dimethyl vinyl-terminated silicone oil is 5-20.

[0014] Preferably, the reaction temperature of the polymerization reaction is 80-100°C.

[0015] Preferably, the reaction temperature during the copolymerization reaction is 100-120°C.

[0016] Preferably, the mass ratio of toluene, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane is 9-11:9-11:0.8-1.1; and the tetramethylammonium hydroxide is 0.4%-0.6% of the total mass of octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane.

[0017] Preferably, the mass ratio of the dimethyl vinyl-terminated silicone oil to the octamethylcyclotetrasiloxane is 2 to 4:10.

[0018] Preferably, the platinum catalyst is a platinum silicone oil solution; and the platinum content in the platinum silicone oil solution is 2000 ppm.

[0019] Preferably, the amount of the platinum catalyst used is 5-10 ppm of the mixed material.

[0020] Preferably, the mass ratio of the methylphenyl-terminated vinyl polysiloxane to the inhibitor, the methylphenyl-side-chain hydrogen-containing silicone oil, and the methylphenyl-terminated hydrogen-containing silicone oil is 9-11:0.01:0.56:0.32.

[0021] Preferably, the inhibitor is 1-ethynyl-1-cyclohexanol.

[0022] The second object of the present invention is to provide a phenyl silicone elastomer for high-power semiconductor device packaging prepared by the above preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] Existing dimethyl silicone elastomers cannot meet the requirements of high-power semiconductor devices for heat and electricity resistance, while the preparation method of the present invention is easy to operate, is conducive to promotion and large-scale production, and is suitable for the synthesis of phenyl silicone elastomers for packaging high-voltage and high-power semiconductor devices.

[0025] The phenyl silicon elastomer prepared by the present invention has a strong tolerance in terms of molecular vibration, charge behavior and bubble discharge. On the basis of the traditional dimethyl silicon elastomer, the present invention introduces a large volume phenyl group to increase the steric hindrance of the silicon elastomer material, and the π-π interaction between the large volume phenyl groups introduced at the same time also effectively enhances the intermolecular force. These two factors significantly increase the internal rotation resistance of the silicon elastomer molecular chain, can effectively suppress the vibration phenomenon caused by the segment movement, and enhance its ability to withstand high voltage. Moreover, the phenyl group has a higher bond energy, and the large π bond in the conjugated structure transfers the excitation energy between molecules or within molecules, thereby avoiding the breakage of the bond, and thus has a stronger ability to withstand high temperatures. Therefore, compared with traditional organosilicon elastomers, the electrical and temperature resistance of the phenyl silicon elastomer prepared by the present invention is greatly improved, the maximum breakdown voltage under the power frequency AC electric field can reach 71kv / mm, the temperature resistance can reach 250℃, and it can work in a 200℃ environment for a long time, which can better meet the packaging requirements of new high-power semiconductor devices, provide help for the development of semiconductor devices, and have important significance for the progress of high-power semiconductor devices and the development of new power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The macroscopic morphology of the samples of Comparative Example 1 and Example 1 before and after aging; wherein, Figure 1 (a) is a photo of the sample before aging in comparative example 1. Figure 1 (b) is a photo of the sample before aging in Example 1. Figure 1 (c) is a photo of the sample after aging in comparative example 1. Figure 1 (d) is a photograph of the sample after aging in Example 1.

[0027] Figure 2These are the test results of the breakdown voltage of methyl silicone elastomer and phenyl silicone elastomer. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0029] The present invention provides a phenyl silicone elastomer for high-power semiconductor device packaging, and the preparation method thereof is as follows:

[0030] Step 1, preparation of methylphenyl vinyl-terminated polysiloxane:

[0031] In a protective gas atmosphere, toluene is used as a solvent, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane are used as raw materials, and a polymerization reaction is carried out under the catalysis of tetramethylammonium hydroxide to obtain methylphenyl polysiloxane; dimethyl vinyl-terminated silicone oil is used as a capping agent, and the methylphenyl polysiloxane is copolymerized to obtain methylphenyl vinyl-terminated polysiloxane.

[0032] It should be noted that, considering that octaphenylcyclotetrasiloxane is a solid and is not easy to participate in the reaction, the present invention preferably uses toluene as a solvent, uses octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane as raw materials, and uses tetramethylammonium hydroxide as a catalyst, so that octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane are polymerized under the catalytic action of tetramethylammonium hydroxide to form methylphenylpolysiloxane.

[0033] In order to ensure that octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane can undergo polymerization reaction under the catalytic action of tetramethylammonium hydroxide to form methylphenyl polysiloxane, in a preferred embodiment of the present invention, the polymerization reaction is carried out under stirring, and the polymerization reaction temperature is 80-100° C., the stirring rate is 300-600 r / min, and the reaction time is 10-20 min, so that each material is fully contacted and reacted through continuous stirring, and then fully polymerized to form methylphenyl polysiloxane.

[0034] The present invention takes into account that toluene is easy to volatilize and deflagrate. In order to improve the safety of the reaction, the present invention preferably first evacuates a reaction vessel containing toluene, octamethylcyclotetrasiloxane, octaphenylcyclotetrasiloxane and tetramethylammonium hydroxide at room temperature, and then passes nitrogen after observing that there are no obvious bubbles in the solution in the reaction vessel. This is repeated at least 5 times to ensure that the first heating and stirring treatment is carried out in an atmosphere protected by nitrogen, thereby improving the safety of the reaction.

[0035] In order to further ensure that tetramethylammonium hydroxide can catalyze the reaction between the above materials, in a preferred embodiment of the present invention, the amount of tetramethylammonium hydroxide is 0.4% to 0.6% of the total mass of octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane.

[0036] It should also be noted that the present invention takes into account that the traditional end-capping agent tetramethyldisiloxane is volatile, so the present invention uses dimethyl-terminated vinyl silicone oil as the end-capping agent, and in a preferred embodiment of the present invention, the viscosity of the dimethyl-terminated vinyl silicone oil used is 5 to 20, that is, low-viscosity dimethyl-terminated vinyl silicone oil is used as the end-capping agent.

[0037] In order to maintain the nitrogen atmosphere in the reactor and avoid the introduction of air, the present invention preferably adopts the injection method to inject the dimethyl vinyl-terminated silicone oil into the methylphenyl polysiloxane obtained above, so that the vinyl silicone oil and the methylphenyl polysiloxane terminate the vinyl groups to form the vinyl-terminated methylphenyl polysiloxane. The reaction equation of the whole reaction to form the vinyl-terminated methylphenyl polysiloxane is shown in Formula I.

[0038]

[0039] Formula I.

[0040] Taking into account the actual preparation reaction process, since the above-mentioned polymerization reaction is carried out in a toluene solvent environment, the reaction liquid obtained after the actual polymerization reaction contains other components such as reaction solvents in addition to the polymerization product methylphenylpolysiloxane. However, in order to facilitate improving the reaction effect, there is no need to post-treat the reaction liquid obtained after the polymerization reaction. The dimethyl vinyl-terminated silicone oil can be directly injected into the reaction liquid obtained after the above-mentioned polymerization reaction to carry out a copolymerization reaction.

[0041] In order to ensure that the copolymerization reaction of the dimethyl vinyl-terminated silicone oil and the methylphenyl polysiloxane in the reaction solution obtained after the polymerization reaction is fully reacted, in a preferred embodiment of the present invention, the above-mentioned copolymerization reaction is carried out under stirring, and the reaction temperature during the copolymerization reaction is 100-120°C, the stirring rate is 400-600r / min, and the reaction time is 1.5-2.5h.

[0042] The present invention takes into account that in addition to the methylphenyl-terminated vinyl polysiloxane, the reaction liquid obtained by the above copolymerization reaction may also contain impurities such as reaction solvent toluene, catalyst tetramethylammonium hydroxide and other small molecular products. Therefore, in order to improve the purity of the methylphenyl-terminated vinyl polysiloxane and to improve the efficiency of the subsequent composite formation of a phenyl silicone elastomer for high-power semiconductor device packaging, the present invention also performs the following post-treatment.

[0043] 1) Removal of toluene:

[0044] The present invention takes into account that the presence of toluene in the reaction liquid obtained by the above copolymerization reaction will affect the final acquisition of pure methylphenyl-terminated vinyl polysiloxane, so the present invention first cools the reaction liquid obtained by the above copolymerization reaction to 70-80°C, and then performs condensation distillation at 0.08-0.09Mpa to remove the toluene in the reaction liquid by condensation distillation. Among them, the above-mentioned negative pressure of 0.08-0.09Mpa can be adjusted appropriately, as long as the reaction liquid can be maintained to be slightly boiling, and be careful not to boil violently. The reaction time is not limited, and the toluene can be considered to be completely removed when the reaction liquid is treated until there are no obvious bubbles.

[0045] In order to improve the removal effect of toluene, the present invention performs a vacuum treatment on the obtained mixed solution system to completely remove toluene through the vacuum treatment. In order to ensure that the above purpose can be achieved, in a preferred embodiment of the present invention, the reaction time of the vacuum treatment is 50 to 60 minutes.

[0046] 2) Removal of catalyst tetramethylammonium hydroxide:

[0047] The present invention takes into account that tetramethylammonium hydroxide may remain in the system, which will affect the final acquisition of pure methylphenyl vinyl-terminated polysiloxane. Therefore, the present invention heats the reaction solution obtained after removing toluene to 165-175° C. and treats it at 0.08-0.09 MPa for 1.5-2.5 hours to decompose the tetramethylammonium hydroxide into gas at high temperature, thereby destroying the tetramethylammonium hydroxide, thereby improving the purity of the methylphenyl vinyl-terminated polysiloxane, and obtaining pure methylphenyl vinyl-terminated polysiloxane.

[0048] 3) Removal of other small molecule products:

[0049] The present invention takes into account that small molecular products such as phenols may be formed during the reaction process, and such small molecular products may affect the final acquisition of pure methylphenyl vinyl-terminated polysiloxane. Therefore, the present invention further heats the reaction solution after removing the catalyst tetramethylammonium hydroxide to 175-185° C., and then condenses and distills at 0.08-0.09 MPa for 10-20 minutes to further remove the small molecular products, thereby achieving the goal of obtaining pure liquid methylphenyl vinyl-terminated polysiloxane.

[0050] Step 2: Compounding methylphenyl-terminated vinyl polysiloxane with methylphenyl side chain hydrogen-containing silicone oil and methylphenyl-terminated hydrogen-containing silicone oil to form methylphenyl-terminated vinyl polysiloxane:

[0051] The methylphenyl-terminated vinyl polysiloxane is mixed with an inhibitor, a methylphenyl side-chain hydrogen-containing silicone oil and a methylphenyl-terminated hydrogen-containing silicone oil to obtain a mixed material; under the catalytic action of a platinum catalyst, the material is stirred to react so that the components are cross-linked, and the material is cured after vacuum evacuation to obtain the phenyl silicone elastomer for high-power semiconductor device packaging (hereinafter referred to as phenyl silicone elastomer).

[0052] It should be noted that the present invention adds an inhibitor, a methylphenyl side chain hydrogenated silicone oil, and a methylphenyl terminal hydrogenated silicone oil to the methylphenyl terminal vinyl polysiloxane prepared in the above step 1, so that cross-linking occurs under stirring, thereby obtaining a phenyl silicone elastomer. The overall reaction equation of step 2 is shown in Formula II.

[0053]

[0054] Formula II.

[0055] In order to enable the methylphenyl-terminated vinyl polysiloxane, the methylphenyl-side-chain hydrogen-containing silicone oil and the methylphenyl-terminated hydrogen-containing silicone oil to cross-link under the action of a catalyst to form a phenyl silicone elastomer, in a preferred embodiment of the present invention, the mass ratio of the methylphenyl-terminated vinyl polysiloxane to the inhibitor, the methylphenyl-side-chain hydrogen-containing silicone oil and the methylphenyl-terminated hydrogen-containing silicone oil is 9-11:0.01:0.56:0.32.

[0056] In order to further ensure that the methylphenyl-terminated vinyl polysiloxane, the methylphenyl-side-chain hydrogenated silicone oil and the methylphenyl-terminated hydrogenated silicone oil can be fully mixed, so as to fully cross-link under the action of the catalyst to form a phenyl silicone elastomer, in a preferred embodiment of the present invention, the methylphenyl-terminated vinyl polysiloxane, the methylphenyl-side-chain hydrogenated silicone oil and the methylphenyl-terminated hydrogenated silicone oil are first fully mixed by stirring, and the stirring is performed at least 3 times, the stirring rate during each stirring is 2000-3000 r / min, and the stirring time for each stirring is 40-80 s, so as to ensure that the methylphenyl-terminated vinyl polysiloxane, the methylphenyl-side-chain hydrogenated silicone oil and the methylphenyl-terminated hydrogenated silicone oil are fully mixed.

[0057] In a preferred embodiment of the present invention, the inhibitor used is 1-ethynyl-1-cyclohexanol.

[0058] It should also be noted that the present invention takes into account that if the above-obtained mixed material is directly subjected to a cross-linking reaction, the cross-linking reaction rate is slow, so the present invention adds a catalyst to the above-obtained mixed material so that the mixed material is subjected to the catalytic action of the catalyst to increase the cross-linking reaction rate. In order to ensure that the above-mentioned purpose can be achieved, in a preferred embodiment of the present invention, a platinum catalyst is used as a catalyst, and the content of the catalyst is 5 to 10 ppm of the mixed material. Among them, the platinum catalyst used in the present invention is a platinum silicone oil solution; and the platinum content in the platinum silicone oil solution is 2000 ppm.

[0059] In order to fully mix the platinum catalyst to promote the reaction rate of the cross-linking reaction, in another preferred embodiment of the present invention, the platinum catalyst is fully mixed by stirring and stirred at least 3 times, the stirring rate of each stirring is 2000-3000 r / min, and the stirring time of each stirring is 30-60 s.

[0060] It should also be noted that in order to avoid the presence of bubbles in the phenyl silicone elastomer for high-power semiconductor device packaging obtained in the present invention, the cross-linked product obtained by the cross-linking reaction of the present invention is subjected to vacuum exhaust treatment at least 3 times, and each time lasts for 5 minutes to remove the bubbles, thereby ensuring that no obvious bubbles are present in the phenyl silicone elastomer for high-power semiconductor device packaging obtained after curing.

[0061] In order to ensure that a solid phenyl silicone elastomer can be obtained, in a preferred embodiment of the present invention, the temperature of the curing treatment is 100-110°C.

[0062] Example 1

[0063] This embodiment provides a phenyl silicone elastomer for high-power semiconductor device packaging, and its preparation method is as follows:

[0064] Step 1: Preparation of methylphenyl vinyl-terminated polysiloxane

[0065] 1) Preheat the oil bath to 90°C and set aside.

[0066] 2) In a three-necked flask, 10 mL of toluene, 10 mL of octamethylcyclotetrasiloxane, 1 g of octaphenylcyclotetrasiloxane, and 0.05 g of catalyst tetramethylammonium hydroxide were added in sequence, and stirred with a magnetic stirrer to obtain a mixed material.

[0067] 3) At room temperature, the three-necked flask containing the mixed material obtained above was evacuated, and nitrogen was introduced after observing that there were no obvious bubbles in the solution. This step was repeated 5 times to ensure that the air in the system was removed so that the subsequent reaction could be carried out under a nitrogen environment.

[0068] 4) Seal the mouth of the flask with a gas bag filled with nitrogen to maintain a nitrogen atmosphere, then place the treated three-necked flask in the oil bath preheated to 90° C., set the magnetic speed to 500 r / min, react for 15 min, and obtain a mixed solution C.

[0069] 5) Inject 3 ml of dimethyl vinyl-terminated silicone oil with a viscosity of 5-20 with a syringe, heat to 110°C, and continue stirring at 110°C at a speed of 500 r / min for 2 h to obtain a mixed solution D.

[0070] 6) After cooling the mixed solution D obtained above to 75°C, connect it to a condensation distillation apparatus (note, cool first and then distill), connect it to a vacuum pump, adjust the air inlet valve, maintain the negative pressure at 0.08-0.09 MPa, until there are no obvious bubbles in the solution, evacuate for 55 minutes to completely remove toluene, and obtain a mixed solution E.

[0071] 7) After the mixed solution E was heated to 170° C., the negative pressure was 0.09 MPa, and condensation and distillation were performed for 2 h to destroy tetramethylammonium hydroxide to obtain a mixed solution F.

[0072] 8) After the mixed solution F is heated to 180° C., condensation and distillation are continued at a negative pressure of 0.09 MPa for 15 min to further remove volatile phenol, thereby obtaining the methylphenyl vinyl-terminated polysiloxane.

[0073] Step 2: Preparation of phenyl silicone elastomer

[0074] 1) Take 10 mL of the above-prepared methylphenyl-terminated vinyl silicone oil, then add 0.01 mL of 1-ethynyl-1-cyclohexanol, 0.56 mL of methylphenyl side chain hydrogenated silicone oil, and 0.32 mL of methylphenyl-terminated hydrogenated silicone oil in sequence, and then stir in a high-speed stirrer for 3 times, each time stirring at a stirring rate of 2500 r / min for 1 min to obtain a mixed solution A.

[0075] 2) Add 0.05 mL of a platinum silicone oil solution having a platinum content of 2000 ppm to the mixed solution A, and then stir the mixture in a stirrer for 3 times, each time at a speed of 2500 r / min for 40 s, to obtain a mixed solution B.

[0076] 3) The mixed solution B obtained above was vacuum-evacuated 3 times, each time lasting 5 minutes.

[0077] 4) The vacuum-evacuated solution is allowed to stand at 105° C. for curing to obtain a phenyl silicone elastomer for high-power semiconductor device packaging.

[0078] Example 2

[0079] This embodiment provides a phenyl silicone elastomer for high-power semiconductor device packaging, and its preparation method is as follows:

[0080] 1) Preheat the oil bath to 80°C and set aside.

[0081] 2) In a three-necked flask, 10 mL of toluene, 9 mL of octamethylcyclotetrasiloxane, 0.9 g of octaphenylcyclotetrasiloxane, and 0.042 g of catalyst tetramethylammonium hydroxide were added in sequence, and stirred with a magnetic stirrer to obtain a mixed material.

[0082] 3) At room temperature, the three-necked flask containing the mixed material obtained above was evacuated, and nitrogen was introduced after observing that there were no obvious bubbles in the solution. This step was repeated 5 times to ensure that the air in the system was removed so that the subsequent reaction could be carried out under a nitrogen environment.

[0083] 4) Seal the mouth of the flask with a gas bag filled with nitrogen to maintain a nitrogen atmosphere, then place the treated three-necked flask in the oil bath preheated to 80° C., set the magnetic speed to 300 r / min, react for 10 min, and obtain a mixed solution C.

[0084] 5) Inject 2.5 ml of dimethyl vinyl-terminated silicone oil with a viscosity of 5-20 with a syringe, heat to 100°C, and continue stirring at 100°C at a speed of 300 r / min for 2 h to obtain a mixed solution D.

[0085] 6) After cooling the mixed solution D obtained above to 70°C, connect it to a condensation distillation apparatus (note, cool first and then distill), connect it to a vacuum pump, adjust the air inlet valve, maintain the negative pressure at 0.08-0.09 MPa, until there are no obvious bubbles in the solution, evacuate for 55 minutes to completely remove toluene, and obtain a mixed solution E.

[0086] 7) After the mixed solution E was heated to 165° C., the negative pressure was 0.09 MPa, and condensation and distillation were performed for 2 h to destroy tetramethylammonium hydroxide to obtain a mixed solution F.

[0087] 8) After the mixed solution F is heated to 175° C., condensation and distillation are continued at a negative pressure of 0.09 MPa for 10 min to further remove volatile phenol, thereby obtaining the methylphenyl vinyl-terminated polysiloxane.

[0088] Step 2: Preparation of phenyl silicone elastomer

[0089] 1) Take 10 mL of the above-prepared methylphenyl-terminated vinyl silicone oil, then add 0.01 mL of 1-ethynyl-1-cyclohexanol, 0.32 mL of methylphenyl side chain hydrogenated silicone oil, and 0.56 mL of methylphenyl-terminated hydrogenated silicone oil in sequence, and then stir in a high-speed stirrer for 3 times, each time stirring at a stirring rate of 2000 r / min for 1 min to obtain a mixed solution A.

[0090] 2) Add 0.05 mL of a platinum silicone oil solution having a platinum content of 2000 ppm to the mixed solution A, and then stir the mixture in a stirrer for 3 times, each time at a speed of 2000 r / min for 30 s, to obtain a mixed solution B.

[0091] 3) The mixed solution B obtained above was vacuum-evacuated 3 times, each time lasting 5 minutes.

[0092] 4) The vacuum-evacuated solution is allowed to stand at 100° C. for curing to obtain a phenyl silicone elastomer for high-power semiconductor device packaging.

[0093] Example 3

[0094] This embodiment provides a phenyl silicone elastomer for high-power semiconductor device packaging, and its preparation method is as follows:

[0095] 1) Preheat the oil bath to 100°C and set aside.

[0096] 2) In a three-necked flask, 10 mL of toluene, 11 mL of octamethylcyclotetrasiloxane, 1.1 g of octaphenylcyclotetrasiloxane, and 0.055 g of catalyst tetramethylammonium hydroxide were added in sequence, and stirred with a magnetic stirrer to obtain a mixed material.

[0097] 3) At room temperature, the three-necked flask containing the mixed material obtained above was evacuated, and nitrogen was introduced after observing that there were no obvious bubbles in the solution. This step was repeated 5 times to ensure that the air in the system was removed so that the subsequent reaction could be carried out under a nitrogen environment.

[0098] 4) Seal the mouth of the flask with a gas bag filled with nitrogen to maintain a nitrogen atmosphere, then place the treated three-necked flask in the oil bath preheated to 100° C., set the magnetic speed to 600 r / min, react for 20 min, and obtain a mixed solution C.

[0099] 5) Inject 3.2 ml of dimethyl vinyl-terminated silicone oil with a viscosity of 5-20 with a syringe, heat to 120°C, and continue stirring at 120°C at a speed of 600 r / min for 2 h to obtain a mixed solution D.

[0100] 6) After cooling the mixed solution D obtained above to 80°C, connect it to a condensation distillation apparatus (note, cool first and then distill), connect it to a vacuum pump, adjust the air inlet valve, maintain the negative pressure at 0.08-0.09 MPa, until there are no obvious bubbles in the solution, evacuate for 60 minutes to completely remove toluene, and obtain a mixed solution E.

[0101] 7) After the mixed solution E was heated to 175° C., the negative pressure was 0.09 MPa, and condensation and distillation were performed for 2 h to destroy tetramethylammonium hydroxide to obtain a mixed solution F.

[0102] 8) After the mixed solution F is heated to 185° C., condensation and distillation are continued at a negative pressure of 0.09 MPa for 20 min to further remove volatile phenol, thereby obtaining the methylphenyl vinyl-terminated polysiloxane.

[0103] Step 2: Preparation of phenyl silicone elastomer

[0104] 1) Take 10 mL of the above-prepared methylphenyl-terminated vinyl silicone oil, then add 0.01 mL of 1-ethynyl-1-cyclohexanol, 0.32 mL of methylphenyl side chain hydrogenated silicone oil, and 0.56 mL of methylphenyl-terminated hydrogenated silicone oil in sequence, and then stir in a high-speed stirrer for 3 times, each time stirring at a stirring rate of 2500 r / min for 1 min to obtain a mixed solution A.

[0105] 2) Add 0.05 mL of a platinum silicone oil solution having a platinum content of 2000 ppm to the mixed solution A, and then stir the mixture in a stirrer for 3 times, each time at 3000 r / min for 1 min, to obtain a mixed solution B.

[0106] 3) The mixed solution B obtained above was vacuum-evacuated 3 times, each time lasting 5 minutes.

[0107] 4) The vacuum-evacuated solution is allowed to stand at 110° C. for curing to obtain a phenyl silicone elastomer for high-power semiconductor device packaging.

[0108] Comparative Example 1

[0109] In this comparative example, methyl silicone elastomer, a traditional power electronic device packaging material, is used as the elastomer for packaging high-power semiconductor devices.

[0110] Experimental Section

[0111] (I) Aging test

[0112] The present invention takes the elastomer materials prepared in Example 1 and Comparative Example 1 as examples, and respectively places them in a vacuum drying oven at 200 degrees for 24 hours for aging test, and the test results are as follows: Figure 1 shown.

[0113] in, Figure 1 (a) is a sample photo (macro morphology) of comparative example 1 before aging. Figure 1 (b) is a photo of the sample before aging in Example 1. Figure 1 (c) is a photo of the sample after aging in comparative example 1. Figure 1 (d) is a photograph of the sample after aging in Example 1.

[0114] Depend on Figure 1It can be seen from the test results that the methyl silicone elastomer of comparative example 1 turns yellow obviously after aging, indicating that the methyl silicone elastomer of comparative example 1 has undergone serious aging. The phenyl silicone elastomer prepared in Example 1 of the present invention is still transparent after aging, does not turn yellow, and does not have agglomeration, indicating that the phenyl silicone elastomer of Example 1 has no aging phenomenon, which shows that the phenyl silicone elastomer prepared by the preparation method of the present invention has better high temperature resistance and yellowing resistance than traditional methyl silicone elastomer. Traditional silicone elastomers easily react with oxygen at high temperatures, resulting in main chain degradation, small molecular volatiles and disordered carbon residues, causing yellowing and degradation of the material. On the one hand, the conjugated structure of the phenyl group enhances the antioxidant properties of the phenyl silicone elastomer. On the other hand, since the phenyl group is a rigid group, its introduction can prevent the main chain cross-linking or degradation caused by the oxidative decomposition of the side chain group, and enhances the thermal stability of the phenyl elastomer, which means that the phenyl silicone elastomer can maintain stable physical and chemical properties at higher temperatures.

[0115] (II) Breakdown voltage test

[0116] The present invention tests the breakdown voltage of the methyl silicone elastomer of comparative example 1 and the phenyl silicone elastomer of embodiment 1. The test results are as follows: Figure 2 shown.

[0117] The test method is: applying a DC voltage at a boost rate of 1 kV / s per second to test the breakdown performance of phenyl and methyl samples under a DC electric field.

[0118] Depend on Figure 2 From the test results, it can be seen that the breakdown voltage of the methyl silicone elastomer of comparative example 1 is only 53.53 kv / mm, while the breakdown voltage of the phenyl silicone elastomer of embodiment 1 is 66.43 kv / mm, and the maximum breakdown voltage can reach 71 kv / mm under the industrial frequency AC electric field, which is 24.5% higher than the breakdown voltage of comparative example 1, indicating that the phenyl silicone elastomer prepared in embodiment 1 has better high voltage resistance than the traditional methyl silicone elastomer, indicating that the insulation strength of the phenyl silicone elastomer prepared by the present invention will be more suitable for packaging needs.

[0119] This may be related to the introduction of phenyl groups into the side groups of silicone elastomers. This is due to the unique conjugated structure of phenyl groups, which has a large electron affinity, enabling them to capture high-energy electrons and dissipate energy, thereby improving the electrical resistance of the material. In addition, due to the presence of its π electron cloud, phenyl groups have a higher polarity than methyl groups. This increase in polarity is conducive to enhancing the interaction force within the material and improving the stability and insulation properties of the material.

[0120] Obviously, the above embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing a phenyl silicone elastomer for high-power semiconductor device packaging, characterized in that: The following steps are involved: In a protective gas atmosphere, toluene is used as a solvent, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane are used as raw materials, and a polymerization reaction is carried out under the catalysis of tetramethylammonium hydroxide to obtain methylphenyl polysiloxane; dimethyl vinyl-terminated silicone oil is used as a capping agent, and a copolymerization reaction is carried out with the methylphenyl polysiloxane to obtain methylphenyl vinyl-terminated polysiloxane; the mass ratio of toluene, octamethylcyclotetrasiloxane and octaphenylcyclotetrasiloxane is 9-11:9-11:0.8-1.1; The methylphenyl-terminated vinyl polysiloxane is mixed with an inhibitor, a methylphenyl side-chain hydrogen-containing silicone oil and a methylphenyl-terminated hydrogen-containing silicone oil to obtain a mixed material; under the catalytic action of a platinum catalyst, the material is stirred to react so that each component is cross-linked, and the material is cured after vacuum evacuation treatment to obtain the phenyl silicone elastomer for high-power semiconductor device packaging; Wherein, the viscosity of the dimethyl vinyl-terminated silicone oil is 5 to 20; The reaction temperature of the polymerization reaction is 80-100°C; The mass ratio of the methylphenyl-terminated vinyl polysiloxane to the inhibitor, the methylphenyl-side-chain hydrogen-containing silicone oil, and the methylphenyl-terminated hydrogen-containing silicone oil is 9-11:0.01:0.56:0.

32.

2. The preparation method according to claim 1, characterized in that The reaction temperature during the copolymerization reaction is 100-120°C.

3. The preparation method according to claim 1, characterized in that: The tetramethylammonium hydroxide is 0.4% to 0.6% of the total mass of the octamethylcyclotetrasiloxane and the octaphenylcyclotetrasiloxane.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the dimethyl vinyl-terminated silicone oil to the octamethylcyclotetrasiloxane is 2-4:

10.

5. The preparation method according to claim 1, characterized in that: The platinum catalyst is a platinum silicone oil solution; and the platinum content in the platinum silicone oil solution is 2000ppm.

6. The preparation method according to claim 1, characterized in that: The amount of the platinum catalyst used is 5-10 ppm of the mixed material.

7. The preparation method according to claim 1, characterized in that: The inhibitor is 1-ethynyl-1-cyclohexanol.

8. A phenyl silicone elastomer for high-power semiconductor device packaging prepared by the preparation method according to any one of claims 1 to 7.

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