JP6349163B2 - Organopolysiloxane prepolymer, organopolysiloxane polymer gel, sealing material for SiC or GaN power module, semiconductor sealing structure - Google Patents

Description

  The present invention relates to an organopolysiloxane prepolymer, an organopolysiloxane polymer gel obtained by heating and solidifying the organopolysiloxane prepolymer, a sealing material for SiC or GaN power modules containing the organopolysiloxane prepolymer, and the organopolysiloxane The present invention relates to a semiconductor sealing structure sealed with a polymer gel.

  When the structure of a power module (semiconductor), which is an electrical component, becomes relatively large, a gel sealing structure that seals the entire circuit including elements with a very soft resin is taken. If it is relatively small, packaging with epoxy resin, so-called discrete structure, is taken, but it is said that stable production is difficult when it exceeds the size of a business card. At present, the element is Si (silicon), and general-purpose elastic materials such as silicone resin are used for gel sealing. However, in recent years, development and practical use of next-generation power modules using SiC or GaN have been accelerated, and the heat-resistant temperature required for gel-sealing materials has become very high.

  Until now, general-purpose resins such as epoxy resins and silicone resins have been used as a material for gel sealing of power modules as described above. These general-purpose resins have a long history, are excellent in productivity and processability, and can be supplied stably at low cost.

  However, as described above, a new elastic body that can be continuously used at 200 ° C. or higher and has high insulating properties has been required when a semiconductor such as SiC or GaN, which is effective in high-temperature operation, is adopted as an element. It was. In SiC and GaN power modules, the required heat-resistant maintenance temperature has been increased from 180 ° C. to 200 ° C. or higher, and it is required to withstand high temperatures of 250 ° C. or higher in the vicinity of the element. Under such high temperatures of around 200 ° C., general-purpose resins such as epoxy resins and silicone resins are prone to many problems such as cracks and breakage due to thermal deterioration and peeling from elements and packages due to poor adhesion. I came.

  Silicone resins are generally said to have heat resistance of 200 ° C. or higher. However, the thermal reaction and electrical insulation by the solidification (curing) catalyst and additives to be blended, the formation of a thermally weak CC bond by addition polymerization for giving priority to solidification (curing), etc. 1,000 Problems such as an increase in hardness, material destruction, and a decrease in adhesiveness with a package under a continuous use environment for more than an hour have become prominent. In particular, in addition polymerization, which is the principle of solidification (curing) of many silicone resins, formation of C—C bonds is unavoidable, and heat deterioration and light deterioration are inevitably caused. Therefore, a sealing material that replaces these general-purpose resins has been demanded in the market.

  In recent years, organic-inorganic hybrid compositions with improved characteristics by incorporating inorganic components into siloxane polymers with relatively high heat resistance in relation to the applications for semiconductor power module sealing materials such as SiC and GaN as described above Things are being developed.

  The organic-inorganic hybrid composition is composed of a polydimethylsiloxane (hereinafter sometimes abbreviated as “PDMS”) corresponding to an organic component, such as flexibility, water repellency, releasability, and the like of the inorganic component. It is a material that has characteristics such as heat resistance and mechanical structure strength, and the solidified body of the organic-inorganic hybrid composition has high heat resistance and flexibility at a continuous use temperature of 200 ° C. or higher, and further high electrical insulation. And a material having excellent electrical characteristics such as low dielectric properties at high frequencies (Patent Documents 1 to 6).

  Organic-inorganic hybrid materials are incorporated in laser diodes (LD), light emitting diodes (LED), LED print heads (LPH), charge coupled devices (CCD), insulated gate bipolar transistors (IGBT), etc. The use as a sealing material for semiconductor elements and connections has been studied.

Japanese Patent Laid-Open No. 1-113429 JP-A-2-182728 JP-A-4-227731 JP 2009-292970 A Republished WO2010 / 090280 Republished WO2012 / 023618

  However, some polyorganosiloxane organic-inorganic hybrid materials have relatively high heat resistance, but the molecular weight distribution of the raw material PDMS is wide and the synthesized organic-inorganic hybrid itself has a wide molecular weight distribution. That is, in the obtained hybrid sol, there are a high-reactivity polymer component and a low-molecular component that cannot contribute to the reaction. Therefore, in order to obtain a solidified body (gel), it is necessary to forcibly solidify (gelate) using a highly active metal compound catalyst. However, a highly active metal compound catalyst remains inside the solidified body even after solidification, and thereafter contributes to bond breakage of the solidified body in a thermal environment. Therefore, when using a highly active solidification catalyst such as Pt, Sn, or Bi, it is desirable not to leave the material used at 200 ° C. or higher.

  In order to avoid such problems, PDMS used as a raw material is required to have a narrow molecular weight distribution. There is a living polymerization method as a method for producing PDMS having a narrow molecular weight distribution. With this method, it is possible to produce PDMS with a relatively narrow molecular weight distribution.

  In order to obtain a sealing material that can be continuously used in a high temperature environment of 200 ° C. to 250 ° C. or higher even when PDMS having a narrow molecular weight distribution is used, it is necessary to further maintain heat resistance and power modules. There is a need to improve adhesion with various materials used.

  Therefore, the object of the present invention is excellent in heat resistance and flexibility, with little change in characteristics even when used continuously for a long time in a high temperature environment of 200 ° C. to 250 ° C. or higher, and cracks due to thermal stress occur. It is an object to provide an organopolysiloxane prepolymer that is difficult to gel, an organopolysiloxane polymer gel obtained by heating and solidifying it, a sealing material for SiC or GaN power modules, and a semiconductor sealing structure.

  The present invention solves the conventional problems, is useful as a sealing material for next-generation power modules using SiC and GaN semiconductor elements, can be used continuously in a high temperature environment, and has excellent electrical insulation characteristics Organopolysiloxane prepolymer, organopolysiloxane polymer gel obtained by heating and solidifying it, sealing material for SiC or GaN power module containing organopolysiloxane prepolymer, and organopolysiloxane polymer gel It is an object of the present invention to provide a stopped semiconductor sealing structure. In this specification, an SiC or GaN power module may be referred to as a semiconductor power module or simply a power module.

  As a result of the study by the present inventors, in order to produce a material that can be continuously used in a high temperature environment of 200 ° C. or higher and has excellent electrical insulation properties, the molecular weight distribution of both end silanol group polydimethylsiloxane as the main raw material Was found to be important. For the evaluation of the molecular weight distribution, the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is used as the molecular weight distribution index. In addition, a highly active solidification catalyst is required, and as a result, heat resistance maintenance may be significantly reduced. If it is 1.4 or less, it shows relatively thermally stable characteristics, but if it is 1.2 or less, the conditions for solidification can be further relaxed, that is, solidification can be performed at low temperature in a short time. Preferably, in view of heat resistance maintenance characteristics at a high temperature of 200 ° C. or higher, the molecular weight distribution index (Mw / Mn) is more preferably 1.1 or lower.

  In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are molecular weights measured by gel permeation chromatography (GPC method) using polystyrene as a standard substance and tetrahydrofuran as an eluent. .

The organopolysiloxane prepolymer (C) according to the present invention is at least one selected from the group consisting of the following (A-1) and the following (B-1), (B-2) and (B-3). It produces | generates by carrying out a condensation reaction with a seed compound (B).
(A-1): Polydimethylsiloxane having silanol groups at both ends, having a number average molecular weight (Mn) of approximately 18,000 to 60,000 and a molecular weight distribution index (Mw / Mn; Mw is a weight average) Molecular weight is 1.4 or less.
(B-1): an alkoxysilane monomer containing an aryl group.
(B-2): A complete or partial hydrolyzate of the alkoxy group possessed by (B-1).
(B-3): A condensation reaction product between (B-2) or (B-2) and (B-1).

  Moreover, in the organopolysiloxane prepolymer (C) of the present invention, the blending ratio (A-1) / (B-1) of (A-1) and (B-1) is 0.15 to 2 (molar ratio). ) Is preferable.

  In addition, in the organopolysiloxane prepolymer (C) of the present invention, it is preferable that the amount of Sn compound added relative to the total amount of (A-1) and (B-1) is 50 ppm or less.

The organopolysiloxane prepolymer (C) of the present invention is preferably produced by further subjecting the above-mentioned organopolysiloxane prepolymer (C) to the condensation reaction of the following (A-2).
(A-2): Polydimethylsiloxane having trialkoxysilyl groups at both ends, having a number average molecular weight (Mn) of about 15,000 to 60,000 and a molecular weight distribution index (Mw / Mn; Mw) Is a weight average molecular weight) of 1.3 or less.

  Moreover, in the organopolysiloxane prepolymer (C) of the present invention, the blending ratio (A-1) / (A-2) of (A-1) and (A-2) is 2 to 20 (molar ratio). Preferably there is.

  In addition, in the organopolysiloxane prepolymer (C) of the present invention, the amount of Sn compound added relative to the total amount of (A-1), (A-2) and (B-1) is 50 ppm or less. preferable.

  In the organopolysiloxane prepolymer (C) of the present invention, the aryl group of (B-1) is at least one selected from the group consisting of a phenyl group, a tolyl group, a naphthyl group, a styryl group, and a biphenyl group. It is preferable that

  Further, the organopolysiloxane prepolymer (C) of the present invention is preferably one condensed with a titanium alkoxide as a catalyst.

  The organopolysiloxane polymer gel (D) according to the present invention can be obtained by heating and solidifying a sol containing any of the above-mentioned organopolysiloxane prepolymers (C).

  Further, when the organopolysiloxane polymer gel (D) of the present invention is formed into a plate-like body having a thickness of 10 mm, the weight reduction rate after passage of 1,000 hours in an environment of 250 ° C. is 10% or less. It is preferable.

  The organopolysiloxane polymer gel (D) of the present invention is measured using a 1/4 conical shape after 1,000 hours have passed in an environment of 250 ° C. when formed into a 10 mm thick plate. It is preferable that the consistency (JIS K 2220) converted to a consistency using a standard cone is 30 or more.

Further, the organopolysiloxane polymer gel (D) of the present invention preferably has a volume resistivity (JIS K 6249) of 10 ¹⁴ Ω · cm or more after elapse of 500 hours in an environment of 250 ° C.

  The sealing material for SiC or GaN power module according to the present invention contains any one of the above organopolysiloxane prepolymers (C).

  The semiconductor encapsulation structure according to the present invention is obtained by encapsulating a SiC or GaN power module with any of the above organopolysiloxane polymer gels (D).

  As described above, according to the present invention, heat resistance and flexibility are excellent, and there is little change in characteristics even when used continuously for a long time in a high temperature environment of 200 ° C. to 250 ° C. It is possible to provide an organopolysiloxane prepolymer that is a gel in which cracks do not easily occur, an organopolysiloxane polymer gel obtained by heating and solidifying the same, a sealing material for SiC or GaN power modules, and a semiconductor sealing structure it can.

ここにｍは２４０〜８１０の整数である。 The present invention is described in detail below.
<Polydimethylsiloxane (A-1) having silanol groups at both ends>
The polydimethylsiloxane (PDMS) (A-1) used for the synthesis of the organopolysiloxane prepolymer (C) of the present invention has silanol groups capable of reacting with the compound (B) described later at both ends. Is represented by the general formula (1).

Here, m is an integer of 240 to 810.

  PDMS (A-1) having a number average molecular weight (Mn) in the range of approximately 18,000 to 60,000 is used. By setting the number average molecular weight (Mn) to approximately 18,000 or more, the sol containing the organopolysiloxane prepolymer (C) of the present invention can be heated and solidified (gelled) in a relatively short time. Moreover, it is possible to improve the mechanical properties (flexibility) of the obtained gel, and it is possible to ensure the heat maintenance property that enables the thermal shock relaxation of the temperature change from high temperature to low temperature, and it is used as a sealing body. The occurrence of cracks in the solidified body is reduced. Further, by setting the number average molecular weight (Mn) to approximately 60,000 or less, it is not necessary to dilute the high viscosity PDMS with a predetermined solvent, and shrinkage due to volatilization of the solvent can be eliminated. In view of heat resistance maintaining properties, viscosity, and the like, a more preferable number average molecular weight is approximately 20,000 to 40,000.

  PDMS (A-1) having a molecular weight distribution index (Mw / Mn) of 1.4 or less is used. The molecular weight distribution index (Mw / Mn) of PDMS (A-1) is preferably 1.2 or less, more preferably 1.1 or less. If the molecular weight distribution index (Mw / Mn) of PDMS (A-1) is 1.4 or less, the gel body of the organopolysiloxane prepolymer (C), that is, the organopolysiloxane polymer gel (D) is heat resistant over a long period of time. It becomes possible to maintain sex. Furthermore, when the molecular weight distribution index (Mw / Mn) of PDMS (A-1) is 1.2 or less, and further 1.1 or less, the organopolysiloxane particularly excellent in heat resistance maintaining characteristics at a high temperature of 200 ° C. or more A polymer gel (D) is obtained.

  The production method of PDMS (A-1) is not particularly limited, but the molecular weight distribution index (Mw / Mn) is 1.4 or less by synthesizing by living anion polymerization method using alkyllithium as an initiator, Those having a narrow molecular weight distribution such as 1.2 or less and 1.1 or less can be produced.

ここにｎは１９５〜８０５の整数である。Ｒ^１は炭素数が１〜３のアルキル基であって、メチル基、エチル基、ｎ-プロピル基、イソプロピル基から選択されるが、全て同一のものでも、部分的にあるいは全て異なっていてもよい。Ｒ^１は、反応性、安全面および反応制御の観点から、エチル基であることが最も好ましい。Ｘは酸素または炭素数２以下のアルキレン基であって、同一のものでも、異なっていてもよい。 <Polydimethylsiloxane (A-2) having trialkoxysilyl groups at both ends>
Polydimethylsiloxane (PDMS) (A-2) having trialkoxysilyl groups at both ends that can be used in combination with (A-1) in the synthesis of the organopolysiloxane prepolymer (C) of the present invention has both ends. Having an alkoxysilyl group capable of reacting with the compound (B) described later, and represented by the general formula (2). By using this PDMS (A-2) in combination, the solidification rate can be increased by the action of the hydrolyzable groups at both ends, and the adhesion to various materials used in the power module can be improved.

Here, n is an integer from 195 to 805. R ¹ is an alkyl group having 1 to 3 carbon atoms, and is selected from a methyl group, an ethyl group, an n-propyl group, and an isopropyl group, which may be all the same, partially or all different. Good. R ¹ is most preferably an ethyl group from the viewpoints of reactivity, safety, and reaction control. X is oxygen or an alkylene group having 2 or less carbon atoms, and may be the same or different.

  PDMS (A-2) preferably has a number average molecular weight (Mn) in the range of approximately 15,000 to 60,000. By setting the number average molecular weight (Mn) to approximately 15,000 or more, the mechanical properties (flexibility) of the gel obtained by heating and solidifying the sol containing the organopolysiloxane prepolymer (C) of the present invention is improved. In addition, it is possible to ensure thermal maintenance that enables thermal shock relaxation of temperature change from high temperature to low temperature, and the generation of cracks in the gel used as the sealing body is reduced. Further, by setting the number average molecular weight (Mn) to approximately 60,000 or less, it is not necessary to dilute the high viscosity PDMS with a predetermined solvent, and shrinkage due to volatilization of the solvent used for dilution can be eliminated. In view of heat resistance maintaining properties, viscosity and the like, a more preferred number average molecular weight is approximately 18,000 to 40,000.

  It is preferable to use a PDMS (A-2) having a molecular weight distribution index (Mw / Mn) of 1.3 or less. The molecular weight distribution index (Mw / Mn) of PDMS (A-2) is more preferably 1.1 or less. If the molecular weight distribution index (Mw / Mn) of PDMS (A-2) is 1.3 or less, the organopolysiloxane polymer gel (D), which is a solidified product of the organopolysiloxane prepolymer (C), has long-term heat resistance. Can be maintained. Furthermore, when the molecular weight distribution index (Mw / Mn) of PDMS (A-2) is 1.1 or less, an organopolysiloxane polymer gel (D) having particularly excellent heat resistance maintaining characteristics at a high temperature of 200 ° C. or higher is obtained. It is done.

X in the formula (2) is selected from oxygen or an alkylene group having 2 or less carbon atoms. In consideration of heat resistance, oxygen is preferable, but in consideration of purity as (A-2), narrow molecular weight distribution, and the like, an alkylene group having 2 or less carbon atoms, particularly an ethylene group is preferable. Further, ^{R 1} in the formula (2) is selected from an alkyl group having 1 to 3 carbon atoms. In view of stability and reactivity, R ¹ is most preferably an ethyl group.

<Measurement of average molecular weight>
The average molecular weight of PDMS (A-1) and PDMS (A-2) was measured by gel permeation chromatography (GPC method), and the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) was determined as the molecular weight distribution index. It was. Polystyrene equivalent molecular weight was measured using polystyrene as a standard sample.

In addition, the polystyrene conversion molecular weight measurement by GPC method shall be performed on the following measurement conditions.
a) Measuring instrument: SIC Autosampler Model 09
Sugai U-620 COLUMN HEATER
Uniflows UF-3005S2B2
b) Detector: MILIPORE Waters 410
Differential Refractometer
c) Column: Shodex KF806M x 2 d) Oven temperature: 40 ° C
e) Eluent: Tetrahydrofuran (THF) 1.0 mL / min
f) Standard sample: polystyrene g) Injection amount: 100 μL
h) Concentration: 0.020 g / 10 mL
i) Sample preparation: THF added with 0.2% by weight of 2,6-di-tert-butyl-p-phenol (BHT) was dissolved at room temperature with stirring.
j) Correction: The molecular weight calculation was performed by correcting the deviation of the BHT peak between the calibration curve measurement and the sample measurement.

ここにＡｒはアリール基を示し、Ｒ^２は炭素数１〜３のアルキル基を示す。 <Compound (B)>
In synthesizing the organopolysiloxane prepolymer (C) of the present invention, polydimethylsiloxane (A-1) having silanol groups at both ends and further having a trialkoxysilyl group at both ends can be used in combination depending on the purpose. An alkoxysilane monomer (B-1) containing an aryl group that can smoothly react with polydimethylsiloxane (A-2) is used. (B-1) is represented by the general formula (3).

Here, Ar represents an aryl group, and R ² represents an alkyl group having 1 to 3 carbon atoms.

The aryl group in formula (3) is preferably selected from a phenyl group, a tolyl group, a biphenyl group, a styryl group, a naphthyl group, and the like. In view of thermal stability and reactivity, Ar is preferably a phenyl group or a tolyl group, and most preferably a phenyl group. R ² is an alkyl group having 1 to 3 carbon atoms, and is selected from a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Also good. R ² is most preferably an ethyl group from the viewpoints of reactivity, safety, and reaction control. Note that it is also desirable to use a highly reactive methoxy group if the synthesis environment such as exhaust equipment is substantial and the generation of methanol is not a problem in the gelation (solidification) of the produced sol.

  In the condensation reaction between PDMS (A-1) and, if necessary, PDMS (A-2), the alkoxysilane monomer (B-1) containing an aryl group is hydrolyzed completely or partially. It can become complete or partial hydrolyzate (B-2). Furthermore, it is based on the alkoxy group complete or partial hydrolyzate (B-2), or the alkoxysilane monomer (B-1) containing an aryl group and the alkoxy group complete or partial hydrolyzate (B-2). , A condensation reaction product (B-3) may be present. Considering these, in the synthesis of the organopolysiloxane prepolymer (C) of the present invention, the compound (B) is selected from the group consisting of (B-1), (B-2) and (B-3). At least one kind is subjected to the reaction.

  In the present invention, when synthesizing the organopolysiloxane prepolymer (C), aryl groups, preferably phenyl groups, are PDMS (A-1) and PDMS (A-2) (hereinafter referred to as “PDMS (A It is important that it is present in the structure (B-1), instead of being substituted for the methyl group of In general, a compound containing a phenyl group, in particular, a silicon-based compound is excellent in heat resistance. However, in the present invention, not only the heat resistance of (B-1) itself but also the main skeleton PDMS (A in C) It has the effect of suppressing heat deterioration of the origin part) and improving heat resistance. However, this effect leads to an increase in hardness after solidification when a phenyl group or the like is present in the main skeleton of PDMS (A), and the characteristics as an elastic body are significantly inhibited. Therefore, the compound (B-1) has an aryl group and is reacted with PDMS (A) which is the main skeleton.

<Organopolysiloxane prepolymer (C)>
[Manufacture of sol of organopolysiloxane prepolymer (C)]
In the present invention, as described above, PDMS (A: A-1, A-2) and (B-1), (B-2) and (B-3) based on an alkoxysilane monomer containing an aryl group An organopolysiloxane prepolymer (C) is produced by a condensation reaction of at least one compound (B) selected from the group consisting of:

  In the condensation reaction, a Pt, Bi, or Sn-based catalyst is generally used. However, these metal compound catalysts remain after the synthesis and exhibit a catalytic effect of thermal degradation in a heat-resistant environment after solidification. However, when polydimethylsiloxane (A-2) having trialkoxysilyl groups at both ends is used in combination, the effect as a solidification catalyst for the Sn-based compound is remarkable at the time of solidification by heating. Therefore, it is calculated | required that Sn type compound catalyst is the minimum amount required, and the addition amount of Sn type compound is the sum total with respect to the total amount of (A-1), (A-2), and (B-1). And preferably 50 ppm or less. Moreover, even when not using (A-2) together, it is preferable that the addition amount of a Sn type compound is 50 ppm or less in total with respect to the total amount of (A-1) and (B-1).

  For these reasons, in the present invention, alkoxides such as Ti and Zr are preferably used as the condensation catalyst. In particular, when Ti-based alkoxides are used, a catalytic effect that accelerates the above-described thermal degradation after synthesis is not exhibited. Examples of Ti-based condensation catalysts include tetra (2-ethylhexyl) titanate, titanium tetra n-butoxide, titanium tetraisopropoxide, titanium diisopropoxybis (ethyl acetoacetate), titanium tetraacetylacetonate, and titaniumnium di-2- Examples thereof include ethylhexoxybis (2-ethyl-3-hydroxyhexoxide) and titanium diisopropoxybis (acetylacetonate). Among these, the use of tetra (2-ethylhexyl) titanate having a particularly small color development is preferable.

  The titanium alkoxide is preferably used in an amount of 0.08 to 0.2 mol relative to 1 mol of polydimethylsiloxane (A-1) having silanol groups at both ends. If it is less than 0.08 mol, it may not solidify, and if it exceeds 0.2 mol, the effect does not change. The addition amount of the titanium alkoxide is more preferably 0.09 to 0.15 mol with respect to 1 mol of polydimethylsiloxane (A-1) having silanol groups at both ends.

  When performing the condensation reaction, in order to perform stable hydrolysis of the alkoxysilane monomer (B-1) containing an aryl group, the container used for the reaction is heated in an atmosphere filled with an inert gas. Thus, it is desirable to perform hydrolysis and condensation reactions. Examples of the inert gas include Group 18 elements (helium, neon, argon, krypton, xenon, etc.) that are nitrogen gas and rare gases. Further, these gases may be used in combination. As the hydrolysis method, various methods such as dropping or spraying an appropriate amount of water into the reaction system or introducing water vapor can be used.

  The organopolysiloxane prepolymer (C) is a mixture containing an alkoxysilane monomer (B-1) containing an aryl group and PDMS (A: A-1, A-2) under an inert gas atmosphere. It can be obtained by a condensation reaction in the presence of a condensation catalyst.

  In the condensation reaction, various organic solvents can be added to the mixture of PDMS (A) and compound (B) in order to cause PDMS (A) and compound (B) to react uniformly and efficiently. In consideration of compatibility and volatility at the time of solidification by heating, the organic solvent to be added is preferably tert-butyl alcohol, heptane, toluene, xylene or the like.

  As described above, in the compound (B) that has undergone controlled hydrolysis, it is considered that a part of the alkoxy group of the alkoxysilane monomer containing an aryl group is an —OH group, By heating in the presence, silanol groups present at both ends of PDMS (A-1) and alkoxy groups present at both ends of PDMS (A-2) (or silanol groups generated by hydrolysis) and Causes a condensation reaction involving dehydration or dealcoholization.

  In the compound (B) based on the alkoxysilane monomer (B-1) containing an aryl group, when excess moisture is present, the alkoxy group has a complete or partial hydrolyzate (B-2) of the alkoxy group. Condensation or condensation between (B-2) and (B-1) is accelerated, and clusters are easily formed. Therefore, in order to stably synthesize organopolysiloxane prepolymer (C) by uniformly reacting PDMS (A) and compound (B) based on an alkoxysilane monomer containing an aryl group, the water content is strictly controlled. It is extremely important to have an inert gas atmosphere.

[Combination ratio]
The compounding ratio ((A-1) / (B-1)) of the polydimethylsiloxane (A-1) having silanol groups at both ends and the alkoxysilane monomer (B-1) containing an aryl group is mol. The ratio is preferably set within a range of 0.15 to 2 (PDMS (A-1) is added in an amount of 0.5 to 6.7 mol of compound (B-1) with respect to 1 mol). When the molar ratio of (A-1) / (B-1) is within the above range, the condensation reaction is performed smoothly, and when (B-1) is large, flexibility may be impaired. When there is little B-1, heat resistance maintenance property worsens and it becomes difficult to solidify. The blending ratio ((A-1) / (B-1)) is more preferably in the range of 0.25 to 1.5 in terms of molar ratio.

  When polydimethylsiloxane (A-2) having trialkoxysilyl groups at both ends is used in combination with polydimethylsiloxane (A-1) having silanol groups at both ends, the mixing ratio ((A-1 ) / (A-2)) is set to a molar ratio in the range of 2 to 20 (PDMS (A-1) is added to 0.05 to 0.5 mol with respect to 1 mol of PDMS (A-1)). It is preferable. If the amount of (A-2) added is less than the above range, the solidification rate may be delayed, and the effect of improving the adhesion with various materials used in the power module may be reduced. On the contrary, when the amount of (A-2) added is larger than the above range, the heat resistance maintaining property may be deteriorated. The blending ratio ((A-1) / (A-2)) is more preferably in the range of 4 to 10 in terms of molar ratio.

  The molar ratio referred to here is the number average molecular weight (Mn) of PDMS (A-1 and A-2) measured by gel permeation chromatography (GPC method) using polystyrene as a standard substance and tetrahydrofuran as an eluent. ) And the average molecular weight of the alkoxysilane monomer (B-1) containing an aryl group.

<Organopolysiloxane polymer gel (D)>
The organopolysiloxane polymer gel (D) of the present invention heats and solidifies only the sol of the organopolysiloxane prepolymer (C) or, in some cases, the sol of the organopolysiloxane prepolymer (C) in a limited amount. This is a solidified product obtained by heating and solidifying in the presence of a solidification catalyst. The molecular weight distribution index (Mw / Mn) of PDMS (A-1) used for the organopolysiloxane prepolymer (C) is 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less. Thus, the condensation reaction with the compound (B) can be completed smoothly, so that the heat solidification can proceed more efficiently than before. As a result, an organopolysiloxane polymer gel (D) having excellent heat resistance maintaining properties can be obtained.

  Further, when PDMS (A-2) is used in combination, its molecular weight distribution index (Mw / Mn) is 1.3 or less, preferably 1.1 or less, so that the heat resistance maintaining property is the same as that of PDMS (A-1). An organopolysiloxane polymer gel (D) excellent in the above can be obtained.

  Furthermore, the sol of the organopolysiloxane prepolymer (C) can be solidified (heated and solidified) in the presence of a solidification catalyst (metal compound catalyst), and can be processed at a low temperature in a short time. Examples of the metal compound catalyst include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin bisacetylacetonate and the like, but dibutyltin dilaurate is particularly an organopolysiloxane prepolymer (C) when PDMS (A-2) is added. Great effect when solidified.

<Power module structure>
The main use of the organopolysiloxane prepolymer (C) and the organopolysiloxane polymer gel (D) according to the present invention is a material for a sealing material. Specific examples of the sealing material include, for example, a gel-sealed power module that is covered with a sealing material to protect the semiconductor element. In addition, in the element mounted on the upper surface of the substrate, the terminal provided on the surface of the substrate and the terminal provided on the element are electrically connected by wire bonding, and the wire is connected together with the element by a sealing material. Covered.

  When using the sealing material which has the organopolysiloxane prepolymer (C) of this invention as a main component, a semiconductor element and a bonding wire are sealed by inject | pouring a sealing material into a power module package at least. At this time, care must be taken so that bubbles do not enter the sealing material, and it is desirable to perform a vacuum defoaming process quickly after sealing. Depending on the package structure, there is also a method of removing bubbles by placing it in a high-temperature furnace at around 100 ° C. at once. After that, the element into which the sealing material is injected is put into a high temperature furnace (also referred to as “oven”) and heated to gel the sealing material to obtain a sealing structure with a desired shape.

  The sealing material composed of the organopolysiloxane prepolymer (C) and the organopolysiloxane polymer gel (D) according to the present invention is based on heat generated from a semiconductor element or wire bonding even in a high temperature environment of 180 ° C. to 250 ° C. Since a breakdown phenomenon such as cracking or peeling does not occur and problems such as element breakdown, wire bonding disconnection, and deterioration of insulation do not occur, a high-quality semiconductor element can be provided.

  The organopolysiloxane prepolymer (C) and the organopolysiloxane polymer gel (D) according to the present invention are useful as a sealing material for a power module requiring heat resistance. In addition, the organopolysiloxane prepolymer (C) and the organopolysiloxane polymer gel (D) according to the present invention have higher heat resistance than the silicone-based material, and are thermally reduced by narrowing the molecular weight distribution width of PDMS (A). It can provide a sealing material that is stable and easily solidified, and is useful as a sealing material for next-generation power modules that require high heat resistance such as SiC and GaN.

  The consistency (JIS K 2220) of the organopolysiloxane polymer gel (D) of the present invention is an initial value of 80 to 100, but is hard to be cured even after 1,000 hours at 250 ° C. The gel-sealed power module seals the inside of the case with a gel having a low elastic modulus in order to suppress mechanical stress caused by a temperature impact on the bonding wire for electrical connection between the electrode terminal and the semiconductor element. Consistency is used as an index of the softness of the sealing material. The penetration is defined by JIS K 2220, and this time, the measurement was performed with a quarter-yen cone. A consistency of 30 or more is preferred for stress relaxation.

Not only gel sealing but also sealing material needs insulation. Items necessary for ensuring insulation are volume resistivity and dielectric constant. The conventional silicone has an initial volume resistivity of 10 ¹⁵ Ω · cm, but deteriorates to 10 ¹⁰ to 10 ¹¹ Ω · cm after 500 hours in an environment of 250 ° C. The organopolysiloxane polymer gel (D) of the present invention has a dielectric constant almost equivalent to that of silicone, but exhibits a high insulation property with a volume resistivity of the order of 10 ¹⁷ Ω · cm, and has passed 500 hours in an environment of 250 ° C. Even so, the change is small and the order of 10 ¹⁴ to 10 ¹⁷ Ω · cm can be maintained.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example, this invention is not limited at all by these Examples. In the examples, “parts” and “%” are based on mass (mass parts, mass%) unless otherwise specified.

[Examples 1-2]
[Preparation of Sol Solution of Organopolysiloxane Prepolymer (C)]
A reaction vessel equipped with a stirrer, a thermometer, and a dropping line was sufficiently filled with nitrogen gas. At this time, what was manufactured with the nitrogen gas manufacturing apparatus (Japan Unix Co., Ltd. UNX-200) was used as nitrogen gas.

  Into a reaction vessel sufficiently filled with nitrogen gas, polydimethylsiloxane (PDMS-1) (A-1) and phenyltriethoxysilane (B-1) having silanol groups at both ends are charged and stirred. The temperature was raised to 60 ° C. to prepare Prepolymer Mixture 1.

  Separately, a condensation catalyst solution 2 is prepared by mixing tetra (2-ethylhexyl) titanate, which is a condensation catalyst, and dehydrated ethanol in a container sufficiently filled with nitrogen gas.

  The prepolymer mixed liquid 1 was confirmed to be 60 ° C., the condensation catalyst liquid 2 was added and mixed well, and an organopolysiloxane prepolymer (C ′) was synthesized over 18 hours.

  To the sol containing the organopolysiloxane prepolymer (C ′), polydimethylsiloxane (PDMS-2) (A-2) having trialkoxysilyl groups at both ends and a metal compound catalyst dibutyltin dilaurate are added. A siloxane prepolymer (C) was obtained.

  In addition, the types and masses of PDMS-1 (A-1), PDMS-2 (A-2) and phenyltriethoxysilane (B-1) used in each Example, the respective molar ratios, the amount of condensation catalyst, The molar ratio of the condensation catalyst to A-1, the amount of metal compound catalyst, and the amount of dehydrated ethanol are as follows. In the above reaction, it is necessary to find conditions under which stirring is sufficiently performed. At the time of stirring, if the reaction solution touches the outside air too much, the reaction is promoted and a whitened product may be generated.

Example 1
PDMS-1 (A-1); manufactured by JNC, FM9927 (solvent removal product by molecular distillation apparatus), number average molecular weight (Mn) = 32,000, molecular weight distribution index (Mw / Mn) = 1.09
Phenyltriethoxysilane (B-1); manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37
PDMS-2 (A-2); manufactured by JNC, FM8826, number average molecular weight (Mn) = 20,000, molecular weight distribution index (Mw / Mn) = 1.06
Molar ratio: PDMS-1 (A-1) is 445 g, phenyltriethoxysilane (B-1) is 6.5 g, and the molar ratio of PDMS-1 (A-1) to phenyltriethoxysilane (B-1) Is 1: 1.94.
Molar ratio: 445 g of PDMS-1 (A-1) and 50 g of PDMS-2 (A-2), and the molar ratio of PDMS-1 (A-1) and PDMS-2 (A-2) is 1: 0. .18
Condensation catalyst: Tetra (2-ethylhexyl) titanate (TA-30, Matsumoto Fine Chemical Co., Ltd., molecular weight = 564.75) 1 g, dehydrated ethanol; Wako Pure Chemical Industries, Ltd., special grade reagent 20 g
Molar ratio: The molar ratio of PDMS-1 (A-1) to the condensation catalyst is 1: 0.13
Metal compound catalyst: 0.02 g of dibutyltin dilaurate (manufactured by Kyodo Yakuhin). 39.9 ppm with respect to the total amount of 501.5 g of (A-1), (A-2) and (B-1).

(Example 2)
PDMS-1 (A-1); JNC, FM9926 (solvent removal product by molecular distillation apparatus), number average molecular weight (Mn) = 23,000, molecular weight distribution index (Mw / Mn) = 1.10
Phenyltriethoxysilanesilane (B-1); manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37
PDMS-2 (A-2); manufactured by JNC, FM8826, number average molecular weight (Mn) = 20,000, molecular weight distribution index (Mw / Mn) = 1.06
Molar ratio: 252 g of PDMS-1 (A-1), 6 g of phenyltriethoxysilane (B-1), and a molar ratio of PDMS-1 and phenyltriethoxysilane (B-1) of 1: 2.28.
Molar ratio: PDMS-1 (A-1) is 252 g, PDMS-2 (A-2) is 44.7 g, and the molar ratio of PDMS-1 (A-1) to PDMS-2 (A-2) is 1. : 0.20
Condensation catalyst: Tetra (2-ethylhexyl) titanate (TA-30, Matsumoto Fine Chemical Co., Ltd., molecular weight = 564.75) 0.6 g, dehydrated ethanol; Wako Pure Chemical Industries, Ltd., special grade reagent 12 g
Molar ratio: The molar ratio of PDMS-1 (A-1) to the condensation catalyst is 1: 0.097.
Metal compound catalyst: 0.015 g of dibutyltin dilaurate (manufactured by Kyodo Yakuhin). 49.6 ppm with respect to the total amount of 302.7 g of ( A-1), (A-2) and (B-1).

[Examples 3 to 6]
[Preparation of Sol Solution of Organopolysiloxane Prepolymer (C)]
A reaction vessel equipped with a stirrer, a thermometer, and a dropping line was sufficiently filled with nitrogen gas. At this time, what was manufactured with the nitrogen gas manufacturing apparatus (Japan Unix Co., Ltd. UNX-200) was used as nitrogen gas.

  Into a reaction vessel sufficiently filled with nitrogen gas, polydimethylsiloxane (PDMS) (A-1) having silanol groups at both ends and phenyltriethoxysilanesilane (B-1) are charged and stirred for 60 hours. The temperature was raised to 0 ° C. to prepare Prepolymer Mixture 1.

  Separately, tetra (2-ethylhexyl) titanate, which is a metal compound catalyst, and dehydrated ethanol are mixed in a container sufficiently filled with nitrogen gas to prepare a condensation catalyst solution 2.

  The prepolymer mixed liquid 1 was confirmed to be 60 ° C., the condensation catalyst liquid 2 was added and mixed well, and an organopolysiloxane prepolymer (C) was synthesized over 18 hours.

The types and masses of PDMS (A-1) and phenyltriethoxysilane (B-1) used in each example, their molar ratio, the amount of condensation catalyst, the molar ratio of the condensation catalyst relative to A-1, dehydration The amount of ethanol is as follows. In the above reaction, it is necessary to find conditions under which stirring is sufficiently performed. At the time of stirring, if the reaction solution touches the outside air too much, the reaction is promoted and a whitened product may be generated.

(Example 3)
PDMS (A-1): manufactured by JNC, FM9927 (solvent-removed product by molecular distillation apparatus), number average molecular weight (Mn) = 32,000, molecular weight distribution index (Mw / Mn) = 1.09
Phenyltriethoxysilane (B-1); manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37
Molar ratio: PDMS (A-1) is 492 g, phenyltriethoxysilane (B-1) is 7.5 g, and the molar ratio of PDMS (A-1) to phenyltriethoxysilane (B-1) is 1: 2. .03.
Condensation catalyst: Tetra (2-ethylhexyl) titanate (TA-30, Matsumoto Fine Chemical Co., Ltd., molecular weight = 564.75) 1 g, dehydrated ethanol; Wako Pure Chemical Industries, Ltd., special grade reagent 20 g
Molar ratio: The molar ratio of PDMS-1 (A-1) to the condensation catalyst is 1: 0.12.

Example 4
PDMS (A-1); JNC, FM9926 (solvent removal product by molecular distillation apparatus), number average molecular weight (Mn) = 23,000, molecular weight distribution index (Mw / Mn) = 1.10
Phenyltriethoxysilane (B-1); manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37
Molar ratio: PDMS (A-1) was 292.2 g, phenyltriethoxysilane (B-1) was 6.9 g, and the molar ratio of PDMS (A-1) to phenyltriethoxysilane (B-1) was 1. : 2.26.
Condensation catalyst: Tetra (2-ethylhexyl) titanate (TA-30, Matsumoto Fine Chemical Co., Ltd., molecular weight = 564.75) 0.9 g, dehydrated ethanol; Wako Pure Chemical Industries, Ltd., special grade reagent 18 g
Molar ratio: The molar ratio of PDMS-1 (A-1) to the condensation catalyst is 1: 0.13

(Example 5)
PDMS (A-1): manufactured by JNC, FM9927 (solvent-removed product by molecular distillation apparatus), number average molecular weight (Mn) = 32,000, molecular weight distribution index (Mw / Mn) = 1.09
Phenyltriethoxysilane (B-1); manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37
Molar ratio: PDMS (A-1) is 495.5 g, phenyltriethoxysilane (B-1) is 3.5 g, and the molar ratio of PDMS (A-1) to phenyltriethoxysilane (B-1) is 1. : 0.94.
Condensation catalyst: Tetra (2-ethylhexyl) titanate (TA-30, Matsumoto Fine Chemical Co., Ltd., molecular weight = 564.75) 0.85 g, dehydrated ethanol; Wako Pure Chemical Industries, Ltd., special grade reagent 10 g
Molar ratio: The molar ratio of PDMS-1 (A-1) to the condensation catalyst is 1: 0.097.

(Example 6)
PDMS (A-1): manufactured by JNC, FM9927 (solvent-removed product by molecular distillation apparatus), number average molecular weight (Mn) = 32,000, molecular weight distribution index (Mw / Mn) = 1.09
Phenyltriethoxysilane (B-1); manufactured by Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37
Molar ratio: PDMS (A-1) is 484.5 g, phenyltriethoxysilane (B-1) is 14.5 g, and the molar ratio of PDMS (A-1) to phenyltriethoxysilane (B-1) is 1. : 3.98.
Condensation catalyst: Tetra (2-ethylhexyl) titanate (TA-30, Matsumoto Fine Chemical Co., Ltd., molecular weight = 564.75) 1 g, dehydrated ethanol; Wako Pure Chemical Industries, Ltd., special grade reagent 10 g
Molar ratio: The molar ratio of PDMS-1 (A-1) to the condensation catalyst is 1: 0.12.

[Comparative Example 1]
[Preparation of Sol Solution of Organopolysiloxane Prepolymer (C)]
A reaction vessel equipped with a stirrer, a thermometer, and a dropping line was sufficiently filled with nitrogen gas. At this time, what was manufactured with the nitrogen gas manufacturing apparatus (Japan Unix Co., Ltd. UNX-200) was used as nitrogen gas.

Momentive polydimethylsiloxane (PDMS) YF3057 (number average molecular weight (Mn) = 32,000, molecular weight distribution index (Mw / Mn) having silanol groups at both ends in a reaction vessel sufficiently filled with nitrogen gas = 1.59) 492 g of (A'-1) and phenyltriethoxysilane (Tokyo Chemical Industry Co., Ltd., special grade reagent, molecular weight = 240.37) (B-1) 7.5 g were charged and stirred at 60 ° C. The prepolymer mixed solution 1 was prepared. The molar ratio of PDMS (A′-1) to phenyltriethoxysilane (B-1) is 1: 2.03.

Separately, in a container sufficiently filled with nitrogen gas, 1 g of tetra (2-ethylhexyl) titanate (Matsumoto Fine Chemicals TA-30, molecular weight = 564.75), which is a condensation catalyst, and dehydrated ethanol (Wako Pure Chemical Industries, Ltd.) -Special grade reagent) 10 g is mixed to prepare the condensation catalyst solution 2. The molar ratio of PDMS-1 (A′-1) to the condensation catalyst is 1: 0.12.

  It was confirmed that the organopolysiloxane prepolymer mixed solution 1 was 60 ° C., the condensation catalyst solution 2 was added and mixed well, and an organopolysiloxane prepolymer (C) was synthesized over 18 hours.

[Comparative Example 2]
[Preparation of Sol Solution of Organopolysiloxane Prepolymer (C)]
A reaction vessel equipped with a stirrer, a thermometer, and a dropping line was sufficiently filled with nitrogen gas. At this time, what was manufactured with the nitrogen gas manufacturing apparatus (Japan Unix Co., Ltd. UNX-200) was used as nitrogen gas.

Momentive polydimethylsiloxane (PDMS) YF3057 (number average molecular weight (Mn) = 32,000, molecular weight distribution index (Mw / Mn) having silanol groups at both ends in a reaction vessel sufficiently filled with nitrogen gas = 1.59) 295.5 g of (A'-1) and phenyltriethoxysilane (Tokyo Kasei Kogyo Co., Ltd., special grade reagent, molecular weight = 240.37) (B-1) 4.5 g were charged and stirred. The temperature was raised to 140 ° C., 0.036 g of dibutyltin dilaurate (manufactured by Kyodo Yakuhin Co., Ltd.) as a metal compound catalyst was added, and an organopolysiloxane prepolymer (C) was synthesized over 8 hours. The molar ratio of PDMS (A′-1) to phenyltriethoxysilane (B-1) is 1: 2.03. The amount of dibutyltin dilaurate added is 120 ppm with respect to the total amount of 300 g of (A′-1) and (B-1).

[Comparative Example 3]
[Preparation of Sol Solution of Organopolysiloxane Prepolymer (C)]
A reaction vessel equipped with a stirrer, a thermometer, and a dropping line was sufficiently filled with nitrogen gas. At this time, what was manufactured with the nitrogen gas manufacturing apparatus (Japan Unix Co., Ltd. UNX-200) was used as nitrogen gas.

In a reaction vessel sufficiently filled with nitrogen gas, Momentive polydimethylsiloxane (PDMS) YF3804 having a silanol group at both ends and a phenyl group in the molecular skeleton (number average molecular weight (Mn) = 6,000) Molecular weight distribution index (Mw / Mn) = 2.05) (A′-3) 240.3 g and ethyl silicate (manufactured by Tama Chemical Co., Ltd., refined silicate 40: tetraethoxysilane linear 4-6 Oligomer, average molecular weight = 745) (B′-1) 59.7 g was added, and the temperature was raised to 140 ° C. while stirring, and dibutyltin dilaurate as a metal compound catalyst (manufactured by Kyodo Yakuhin Co., Ltd.) 3 g was added and an organopolysiloxane prepolymer (C ′) was synthesized over 8 hours. The molar ratio of PDMS (A′-3) to ethyl silicate: silicate 40 (B′-1) is 1: 2.00.

As a solidifying agent, PDMS manufactured by JNC, FM9925 (solvent removal product by molecular distillation apparatus, number average molecular weight (Mn) = 10,000, molecular weight distribution index (Mw / Mn) = 1.12) 24.9 g in the air. , Zinc octylate (Nihon Chemical Industry, Nikka Octix Zinc: 18%) 2.26 g, and zirconyl 2-ethylhexanoate (Nikka Chemical Nikka Octix Zirconium Zr: 12%) 2.84 g and tert- Butyl alcohol (3.0 g) was mixed to prepare a total of 33 g of liquid. This was added to the synthesized organopolysiloxane prepolymer (C ′) and mixed uniformly to obtain an organopolysiloxane prepolymer (C). The amount of dibutyltin dilaurate added is 909 ppm with respect to (A′-3), (B′-1) and the total amount of non-volatile components 330 g of the solidifying agent.

[Test method for consistency evaluation]
The measurement was performed using a penetrometer according to JIS K 2220. The cone attached to the penetrometer is dropped on a solidified sample (organopolysiloxane polymer gel (D)) of organopolysiloxane prepolymer (C) having a thickness of 10 mm prepared in Examples and Comparative Examples. The depth (consistency) entered in the second was read, calculated based on the following formula, and digitized. The cone used is a ¼ cone. The conversion formula for consistency using a ¼ cone is shown below.
P = 3.75p + 24
Here, P is a desired consistency, and p is a consistency obtained by using a ¼ cone (depth that has entered in 5 seconds).

<Evaluation of heat resistance 1: Weight reduction rate>
[Preparation of sample for evaluation]
The organopolysiloxane prepolymer (C) synthesized in Examples 1 to 6 and Comparative Examples 1 to 3 was filled in an aluminum cup having a diameter of 100 mm and a depth of 20 mm so that the thickness after solidification was 10 mm. Solidified by firing under the conditions. The gel obtained from the aluminum cup was taken out and used as a sample for weight reduction rate evaluation.

〔Evaluation method〕
(Mass measurement evaluation)
In the mass measurement evaluation, the samples of each Example and each Comparative Example were stored in an air at 200 ° C. and 250 ° C. for 1,000 hours in a convection-type drying furnace, and an electronic balance [Mettler Toledo The mass (weight) was measured with New Classic MF (Model: ML204)] manufactured by the company, and the rate of change (mass (weight) reduction) of the mass (weight) decreased with respect to the original mass (weight) [[mass (weight ) Change rate (%) = (initial mass (weight) −mass (weight) after elapse of a predetermined time) / initial mass (weight)] × 100]. The results are shown in Table 2.

<Evaluation of heat resistance 2: Change in hardness>
The organopolysiloxane prepolymer (C) synthesized in Examples 1 to 5 and Comparative Examples 1 to 4 was filled in a glass petri dish with a diameter of 20 mm so that the thickness after solidification was 10 mm, and the firing profile described in Table 1 was obtained. And fired. The prepared sample was stored at 200 ° C. and 250 ° C. for 1,000 hours, and the consistency was measured by ¼-yen according to the measurement method defined in JIS K 2220. The penetrometer is an ELEX SCIENTIFIC CO. , LTD-EX-210ED DEGENTIAL PENTROMETER was used. The measurement results are shown in Table 2.

<Evaluation of electrical insulation>
A 40 mm square, 100 to 200 μm thick film is formed on the center of an aluminum plate of 50 mm square and 0.8 mm thickness, stored at 250 ° C. for 500 hours, and 500 V is applied according to the method described in JIS K 6249. It was applied for a minute and the resistance value at that time was measured. The measuring instruments used were a digital super-insulation / microammeter DSM-8104 manufactured by HIOKI and a plate sample electrode SME-8311 manufactured by HIOKI. The measurement results are shown in Table 2.

〔Evaluation results〕
In the samples of Examples 1 to 6, the weight reduction rate was 10% or less and the volume resistivity was 10 ¹⁵ Ω · cm or more even after being stored in an atmosphere at 250 ° C. for 1,000 hours. In addition, Examples 1 and 2 to which polydimethylsiloxane having triethoxysilyl groups at both ends were added had almost no difference in both consistency and weight loss when stored at 200 ° C. and 250 ° C. The result was 2 orders of magnitude higher than 6.

On the other hand, the sample of Comparative Example 1 had a large molecular weight distribution index (Mw / Mn) of 1.59 , a large weight loss rate, insufficient flexibility, and a low volume resistivity.

  Moreover, although the sample of Comparative Example 2 uses a Sn-based catalyst, it was not cured by heat treatment up to 280 ° C.

  Moreover, since the phenyl group exists in PDMS molecular frame | skeleton in the sample of the comparative example 3, it turns out that a softness | flexibility is insufficient.

[Summary]
From the above results, it can be seen that by setting the molecular weight distribution to 1.4 or less and the molecular weight to 18,000 or more, weight loss at 200 ° C. or more, generation of cracks, and the like can be suppressed, and an increase in hardness can be suppressed.

  From Example 1 and Example 2, the addition of PDMS having a triethoxysilyl group at the terminal suppressed the solidification temperature and time, and the effect of PDMS having a triethoxysilyl group at the terminal could be confirmed. Since the volume resistivity after storage at 250 ° C. for 500 hours is two orders of magnitude higher than that of the other examples, it is considered that an improvement in insulation due to an increase in the number of crosslinking points was obtained.

  As described above, according to the present invention, heat resistance and flexibility are excellent, and there is little change in characteristics even when used continuously for a long time in a high temperature environment of 200 ° C. to 250 ° C. It is possible to provide an organopolysiloxane prepolymer that is a gel in which cracks do not easily occur, an organopolysiloxane polymer gel obtained by heating and solidifying the same, a sealing material for SiC or GaN power modules, and a semiconductor sealing structure it can.

  The polydimethylsiloxane (PDMS) (A-1) having silanol groups at both ends used in the present invention needs to have a narrow molecular weight distribution with a molecular weight distribution index (Mw / Mn) of 1.4 or less. It is.

  Although there is no restriction | limiting in the manufacturing method of PDMS (A-1), the living polymerization method is desirable as a method of producing narrow molecular weight distribution. PDMS using the living polymerization method can have a molecular weight distribution index of 1.4 or less, further 1.2 or less, and even 1.1 or less.

  PDMS (A-1) has a number average molecular weight (Mn) of approximately 18,000 to 60,000. By setting the number average molecular weight (Mn) to approximately 18,000 to 60,000, it is possible to reduce the hardness of the final heat-solidified product and to impart flexibility, and the elongation at break by a tensile test is 150%. It becomes possible to have the above characteristics. A heat-solidified body having such mechanical properties exhibits a heat stress mitigating ability and can maintain heat resistance for a long period of time. In addition, it is more preferable that the number average molecular weight is approximately 20,000 to 40,000 from the viewpoints of higher heat resistance maintaining properties and viscosity. The molecular weight distribution index (Mw / Mn) is required to be 1.4 or less, preferably 1.2 or less, and more preferably 1.1 or less.

  In the present invention, (B-1) an alkoxysilane monomer containing an aryl group and (B-2) an alkoxysilane monomer containing an aryl group as a component to undergo a condensation reaction with PDMS (A-1) Full or partial hydrolyzate, (B-3) Alkoxy silane monomer having aryl group Fully or partially hydrolyzed condensation reaction product of alkoxy groups, or alkoxy group having aryl group-containing alkoxy silane monomer At least one selected from the group consisting of (B-1), (B-2) and (B-3) of a condensation reaction product of a complete or partial hydrolyzate and an alkoxysilane monomer containing an aryl group Compound (B) is subjected to the reaction. In addition to the narrow molecular weight distribution of PDMS (A-1), organo formed by condensation reaction of PDMS (A-1) and alkoxysilane (B-1) containing an aryl group or (B) based thereon The polysiloxane prepolymer (C) can homogenize the solidification reaction and shorten the solidification time, and can obtain an elastic body (gel) having both heat resistance, flexibility and insulation.

  When the organopolysiloxane prepolymer (C) is solidified (gelled), it is not particularly necessary to use a metal compound catalyst for the purpose of accelerating the solidification, and after preliminary drying at 60 to 100 ° C, the temperature is increased to 150 to 200 ° C. And can be solidified. Of course, you may solidify using various metal compound catalysts as needed.

  In the present invention, polydimethylsiloxane (A-2) having trialkoxysilyl groups at both ends is used in addition to polydimethylsiloxane (A-1) having silanol groups at both ends as polydimethylsiloxane. It is also possible. (A-1) Similarly, from the viewpoint of the flexibility and heat resistance maintaining property of the heat-solidified product, the number average molecular weight (Mn) is approximately 15,000 to 60,000, and the molecular weight distribution index (Mw / Mn; Those having an average molecular weight of 1.3 or less are preferably used.

[Example of change]
The present invention is not limited only to the above-described embodiments, and changes, deletions, and additions may be made without departing from the technical idea of the present invention that can be recognized by those skilled in the art from the scope of the claims and the description. Is possible. Moreover, in the said Example, it is not limited to this, You may use the organometallic compound of a different kind and characteristic.

The organopolysiloxane polymer of the present invention provides a solidified product (sealed body) having excellent heat resistance (flexibility) and heat resistance maintenance characteristics, and particularly for SiC, GaN semiconductor power modules and other exothermic element members. Since it is useful as a sealing material or adhesive, it has industrial applicability.

Claims (17)

It is produced by a condensation reaction between the following (A-1) and at least one compound (B) selected from the group consisting of (B-1), (B-2) and (B-3) below. An organopolysiloxane prepolymer.
(A-1): Polydimethylsiloxane having silanol groups at both ends synthesized by a living anion polymerization method , having a number average molecular weight (Mn) of 18,000 to 60,000 and a molecular weight distribution index ( Mw / Mn; Mw is a weight average molecular weight) of 1.4 or less.
(B-1): an alkoxysilane monomer containing an aryl group.
(B-2): A complete or partial hydrolyzate of the alkoxy group possessed by (B-1).
(B-3): A condensation reaction product between (B-2) or (B-2) and (B-1).   The organopolysiloxane prepolymer according to claim 1, wherein the blending ratio (A-1) / (B-1) of the (A-1) and the (B-1) is 0.15 to 2 (molar ratio). . Wherein (A-1) and (B-1) the total amount in pairs and by adding the following Sn compound 50ppm and the produced by a condensation reaction, according to claim 1 or claim 2 Oruganopori Siloxane prepolymer. An organopolysiloxane prepolymer produced by further subjecting the organopolysiloxane prepolymer according to any one of claims 1 to 3 to a condensation reaction with the following (A-2).
(A-2): Polydimethylsiloxane having trialkoxysilyl groups at both ends, the number average molecular weight (Mn) is 15,000-60,000, and the molecular weight distribution index (Mw / Mn; Mw is Weight average molecular weight) is 1.3 or less.   The organopolysiloxane prepolymer according to claim 4, wherein the blending ratio (A-1) / (A-2) of (A-1) and (A-2) is 2 to 20 (molar ratio). Wherein (A-1), (A -2) and (B-1) the total amount in pairs and by adding the following Sn compound 50ppm and the produced by a condensation reaction, according to claim 4 or claim 5. The organopolysiloxane prepolymer according to 5.   The aryl group of (B-1) is at least one selected from the group consisting of a phenyl group, a tolyl group, a naphthyl group, a styryl group, and a biphenyl group, and any one of claims 1 to 6 Item 4. The organopolysiloxane prepolymer according to item.   The organopolysiloxane prepolymer according to any one of claims 1 to 7, which is condensed using a titanium alkoxide as a catalyst. The organopolysiloxane prepolymer according to any one of claims 1 to 8, wherein the molecular weight distribution index (Mw / Mn; Mw is a weight average molecular weight) of (A-1) is 1.2 or less. . The organopolysiloxane prepolymer according to any one of claims 1 to 9, wherein the molecular weight distribution index (Mw / Mn; Mw is a weight average molecular weight) of (A-1) is 1.1 or less. . The organopolysiloxane prepolymer according to any one of claims 4 to 10, wherein the molecular weight distribution index (Mw / Mn; Mw is a weight average molecular weight) of (A-2) is 1.1 or less. . An organopolysiloxane polymer gel , which is a heat-solidified product of a sol containing the organopolysiloxane prepolymer (C) according to any one of claims 1 to 11 . The organopolysiloxane polymer gel according to claim 12 , wherein when formed into a plate-like body having a thickness of 10 mm, the weight reduction rate after 1,000 hours has passed under an environment of 250 ° C is 10% or less. When molded into a plate with a thickness of 10 mm, it is measured using a 1/4 cone after 1,000 hours have passed under an environment of 250 ° C. and converted to a consistency using a standard cone (JIS) The organopolysiloxane polymer gel according to claim 12 or 13 , wherein K2220) is 30 or more. The organopolysiloxane polymer gel according to any one of claims 12 to 14 , wherein a volume resistivity (JIS K 6249) after an elapse of 500 hours in an environment of 250 ° C is 10 ¹⁴ Ω · cm or more. . The sealing material for SiC or GaN power modules containing the organopolysiloxane prepolymer (C) of any one of Claim 1- Claim 11 . A semiconductor encapsulating structure, wherein an SiC or GaN power module is encapsulated with the organopolysiloxane polymer gel (D) according to any one of claims 12 to 15 .