JP6284031B2 - Heat resistant resin composition - Google Patents

Description

  The present invention relates to a heat resistant resin composition. In particular, the present invention is formed by sealing with a heat resistant resin composition suitably used as a sealing material for a semiconductor element using SiC (silicon carbide) or GaN (gallium nitride), and such a heat resistant resin composition. The present invention relates to a semiconductor device.

  Conventionally, in a semiconductor device using a commonly used Si (silicon) semiconductor element, sealing is performed with an epoxy resin or silicone gel to ensure insulation. In recent years, wide band gap materials such as SiC and GaN have been researched and developed because they have superior heat resistance and electrical characteristics compared to Si, and will be replaced with wide band gap materials in the future. It is assumed that A semiconductor element made of a wide band gap material can operate at a higher temperature than Si, but the semiconductor element sealing material is also required to have high heat resistance.

  Generally, as a high heat-resistant thermosetting resin, an alicyclic epoxy compound is used for an epoxy resin, and an acid anhydride type is used for a curing agent.

  As an optical semiconductor encapsulating resin composition, an epoxy resin component composed of an alicyclic epoxy compound and an epoxy resin containing a flexible chain in its skeleton, and a composition containing a cationic polymerization initiator are known. (For example, see Patent Document 1). In the composition, it is necessary to keep the glass transition temperature (Tg) as low as 80 ° C. at the maximum.

JP 2006-299073 A

  The curing reaction of an alicyclic epoxy compound and an acid anhydride curing agent is, for example, when two molecules of an alicyclic epoxy compound and one molecule of a bifunctional acid anhydride curing agent react, The first stage reaction step between the cyclic epoxy compound and one functional group of the acid anhydride curing agent, and the second stage of the remaining one molecule of the alicyclic epoxy compound and the remaining functional group of the acid anhydride curing agent. It is thought to proceed in two stages with the eye reaction process. At this time, since the alicyclic epoxy compound has high steric hindrance, the reaction rate, particularly the second-stage reaction rate, is slow. For this reason, if the curing time is insufficient, only the first-stage reaction is completed, and there is a high possibility that unreacted sites remain in the cured product. When the cured product is exposed to a high temperature, the unreacted site becomes a starting point of a degradation reaction, and there is a problem that cracks occur due to the progress of degradation. Moreover, remaining unreacted sites may lead to a decrease in the degree of cross-linking of the cured product, and the glass transition temperature may decrease. That is, when the cured product is exposed to a high temperature, the mechanical properties change, and cracks and shape changes may occur.

  In view of the above problems, the present inventors have studied to accelerate the second-stage reaction step so as not to leave unreacted sites, and glycidyl ether having a lower steric hindrance than an alicyclic epoxy compound, The present invention was completed by conceiving use with an alicyclic epoxy compound.

  The present invention has been made to solve the above problems. That is, the present invention, according to one embodiment, is a heat resistant resin composition comprising at least a bifunctional alicyclic epoxy compound, at least a bifunctional glycidyl ether, and an acid anhydride curing agent. Become.

  In the heat resistant resin composition, the equivalent ratio of the alicyclic epoxy compound to the glycidyl ether is preferably 0.1 to 1.5.

  In the heat resistant resin composition, it is preferable that the glycidyl ether is contained in an amount of 10 to 60 parts by mass with respect to 100 parts by mass of the alicyclic epoxy compound.

  In the heat resistant resin composition, the alicyclic epoxy compound is preferably 3 ', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate.

  In the heat-resistant resin composition, the at least bifunctional glycidyl ether is preferably bisphenol A diglycidyl ether or cresol novolac-type diglycidyl ether.

  The heat-resistant resin composition is preferably used for sealing a semiconductor element.

  The semiconductor element is preferably a SiC semiconductor element.

According to another embodiment, the present invention is a cured heat resistant resin obtained by curing any of the aforementioned heat resistant resin compositions.
The cured heat-resistant resin preferably has a glass transition temperature of 200 ° C. or higher.

According to another embodiment of the present invention, there is provided a semiconductor device comprising a semiconductor element, an insulating substrate bonded to one surface of the semiconductor element, and an external bonded to the other surface of the semiconductor element. A molded body formed by sealing a member including a printed circuit board for connection with a circuit with a sealing material is provided, and the sealing material covers the semiconductor element and is provided in a region close to the semiconductor element. A first sealing layer, which is a first sealing layer made of a thermosetting resin, and a second sealing layer made of any one of the heat-resistant resin compositions described above, wherein the first sealing layer And a second sealing layer that covers the stop layer and forms at least a part of the outer surface of the molded body.
In the semiconductor device, the semiconductor element is preferably a SiC semiconductor element.

  The heat-resistant resin composition according to the present invention is a highly reliable heat-resistant resin capable of realizing a glass transition temperature of 200 ° C. or higher without causing a decrease in dielectric breakdown voltage or plastic deformation even at an operating temperature of 200 ° C. or higher, for example. Compositions and cured products can be provided. It is particularly useful when used as such a heat-resistant resin composition or semiconductor sealing resin, and can be effectively used for sealing SiC semiconductor elements or GaN semiconductor elements that have high operating temperatures. In addition, the present invention can provide a highly reliable semiconductor device that does not generate cracks even when used under high temperature conditions.

FIG. 1 is a conceptual diagram showing a cross-sectional structure of a semiconductor module molded structure formed by sealing with the heat-resistant resin composition according to the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[First embodiment: Resin composition]
According to the first embodiment, the present invention is a heat resistant resin composition comprising at least a bifunctional alicyclic epoxy compound, at least a bifunctional glycidyl ether, and an acid anhydride curing agent. .

  The at least bifunctional alicyclic epoxy compound may be an epoxy compound provided with 2 or more, 3 or more, or 4 or more alicyclic epoxy groups, and may be one kind of alicyclic epoxy compound or two kinds. A combination of the above different alicyclic epoxy compounds may be used. For example, what is necessary is just an epoxy compound provided with 3, 4- epoxy cyclohexyl group 2 or more, 3 or more, or 4 or more. The at least bifunctional alicyclic epoxy compound may preferably include, but is not limited to, 3 ', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate. The cured product of the alicyclic epoxy compound is particularly excellent in heat resistance, toughness, and transparency as compared with glycidyl ether, and can contribute to these characteristics in the heat resistant resin composition.

  The at least bifunctional glycidyl ether may be an epoxy compound having 2 or more, 3 or more, or 4 or more glycidyl ether groups, and may be one kind of glycidyl ether or a combination of two or more different glycidyl ethers. There may be. Examples include, but are not limited to, bisphenol A diglycidyl ether, phenol novolac glycidyl ether, naphthol novolac glycidyl ether, cresol novolac glycidyl ether, and triphenylmethane type glycidyl ether. Glycidyl ether is superior in terms of crosslinking density because of its faster curing reaction than alicyclic epoxy compounds, and contributes to bending strength, adhesive strength, and thermal properties (high Tg) in heat-resistant resin compositions. obtain.

（各式中、ｎは１〜３０の整数を表す。） The exemplified glycidyl ether may be a low molecular compound, a high molecular compound, and isomers, modified products, and derivatives thereof having the following structural formulas (1) to (7).

(In each formula, n represents an integer of 1 to 30.)

  In the present invention, the equivalent ratio of the alicyclic epoxy compound to the glycidyl ether (epoxy equivalent of alicyclic epoxy compound / epoxy equivalent of glycidyl ether) is preferably 0.1 to 1.5. 0.8 to 1.2 is more preferable, and 0.9 to 1.1 is most preferable. By using a compound in which the equivalent ratio of the alicyclic epoxy compound and the glycidyl ether is in the above range, the reaction between these epoxy compounds and the acid anhydride curing agent can be controlled. That is, it is a two-stage reaction in which at least one functional group of an acid anhydride curing agent is reacted with an alicyclic epoxy compound, and then the remaining functional group of the acid anhydride curing agent is reacted with glycidyl ether. The reaction between the acid anhydride curing agent and at least two epoxy compounds can be promoted. Thereby, the unreacted site | part of a hardening | curing agent and an epoxy compound can be reduced, and the advantage of each characteristic of an alicyclic epoxy compound and a glycidyl ether can be maximized.

  In the heat-resistant resin composition according to the present embodiment, the mass ratio of the alicyclic epoxy compound and glycidyl ether is, for example, 100 parts by mass or less of glycidyl ether with respect to 100 parts by mass of the alicyclic epoxy compound. It is preferable that it is -60 mass parts, and it is more preferable that it is 25-50 mass parts. In order to maintain the characteristic of high Tg peculiar to an alicyclic epoxy compound, it is necessary that the alicyclic epoxy compound is contained in the same mass or more as the glycidyl ether.

  Examples of acid anhydride curing agents include methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl-3,6-endomethylene-1,2,3,6-tetrahydro. Phthalic anhydride, methyl nadic anhydride, hydrogenated methyl nadic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic dianhydride ethylene glycol bisanhydro trimellitate, glyceryl bis Examples include (anhydrotrimellilate) monoacetate and isomers and modified forms thereof, but are not limited thereto. Moreover, an acid anhydride type hardening | curing agent can be used individually by 1 type among these, or can mix and use 2 or more types.

  The content of the acid anhydride curing agent in the heat-resistant resin composition is determined so that the ratio of the epoxy equivalent of the alicyclic epoxy compound, the epoxy equivalent of the glycidyl ether, and the acid anhydride equivalent is 1.0. be able to.

  A curing accelerator may be added as an optional component. This is to control the curing reaction. Specific examples of the curing accelerator include imidazoles such as 2-ethyl-4-methylimidazole, tertiary amines such as benzyldimethylamine, aromatic phosphine such as triphenylphosphine, boron trifluoride monoethylamine, and the like. Lewis acids, boric acid esters, organic metal compounds, organic acid metal salts, and the like are not limited thereto. The addition amount of a hardening accelerator can be 0.01-5 mass parts when a hardening | curing agent is 100 mass parts.

  In particular, when the heat resistant resin composition is used as a resin for semiconductor encapsulation, the heat resistant resin composition may contain an optional component that is usually added to the resin for semiconductor encapsulation. Examples of the optional component include, but are not limited to, a flame retardant, a pigment for coloring a resin, a plasticizer for improving crack resistance, and a silicone elastomer. The amount of these optional components added can be appropriately determined by those skilled in the art depending on the application, but is usually 10% by mass or less when the total mass of the heat-resistant resin composition is 100%.

Moreover, the heat resistant resin composition may further contain an inorganic filler. When the inorganic filler is included, the mass is, for example, 60 to 90 mass%, preferably 80 to 90 mass%, when the mass of the entire heat resistant resin composition is 100%. By including the inorganic filler in such a content, Tg can be further improved. As the inorganic filler, a so-called nanofiller having an average particle diameter of 1 to 100 nm, preferably 5 to 50 nm is used. This is to increase the heat resistance of the resin. In this specification, the average particle diameter means a value measured by a laser diffraction scattering method. The compound constituting the inorganic filler may be one or more selected from the group consisting of SiO ₂ , BN, Al ₂ O ₃ , AlN and Si ₃ N ₄ , but is not limited thereto.

  A cured product can be obtained by curing the heat-resistant resin composition according to the present embodiment having the above composition under appropriate curing conditions. For example, the heat-resistant resin composition can be thermoset by a two-stage thermosetting reaction such as 100 to 140 ° C. for 1 to 3 hours and 160 to 200 ° C. for 1 to 3 hours. The heat-resistant resin composition according to the present embodiment has the characteristics of the above composition, so that Tg is about 200 ° C. or higher, preferably about 210 ° C. or higher, and it is cracked even when used under high temperature conditions after curing. It can be made into a heat-resistant resin cured product that is difficult to enter.

[Second Embodiment]
The present invention is a semiconductor device according to the second embodiment, which is a semiconductor element, an insulating substrate bonded to one surface of the semiconductor element, and an external circuit bonded to the other surface of the semiconductor element. Comprising a molded body formed by sealing a member including a connection printed circuit board with a sealing material, and a thermosetting resin constitutes a first sealing layer that is in contact with and covers the semiconductor element; The heat-resistant resin composition according to an embodiment constitutes a second sealing layer that covers the first sealing layer and is provided facing at least a part of the outer surface of the molded body. .

  FIG. 1 is a diagram illustrating a cross-sectional structure of a semiconductor module molding structure 100, which is an example of a semiconductor device according to a second embodiment. In the semiconductor module molding structure 100, a substantially rectangular parallelepiped first copper block 2 is disposed on the lower surface, which is one surface of the insulating layer 1, and a substantially rectangular parallelepiped second copper block 3 is disposed on the upper surface, which is the other surface. An insulating substrate 4 is configured. A plurality of SiC power semiconductor elements 6 are mounted on and attached to the upper surface of the insulating substrate 4 on the second copper block 3 side via a conductive bonding layer a5. Further, on the upper surface of the SiC power semiconductor element 6, an implant type printed circuit board 9 provided with implant pins 8 is attached by a conductive bonding layer b 7. External connection terminals 10 are attached to the upper surface of the implant-type printed circuit board 9 and the upper surface of the second copper block 3, respectively, so that electrical connection with the outside of the semiconductor module molding structure 100 is possible. The periphery of the SiC power semiconductor element 6 is sealed with a first sealing layer 11 made of a thermosetting resin. Furthermore, the periphery is sealed with a second sealing layer 13 formed by curing the heat-resistant resin composition according to the first embodiment of the present invention to form a molded body. Yes. Further, in the first sealing layer 11, an attachment fitting 12 that is a bolt insertion hole for attaching the semiconductor module molding structure 100 to a cooler (not shown) is embedded. Note that in this specification, the upper surface and the lower surface are relative terms indicating the upper and lower sides in the drawing for the purpose of explanation, and the upper and lower sides are not limited in relation to the usage mode or the like of the semiconductor device.

  In the semiconductor module molded structure 100 according to the present embodiment, the resin sealing portion is composed of two types of resins, that is, the first sealing layer 11 and the second sealing layer 13. The first sealing layer 11 completely covers the periphery of the SiC power semiconductor element 6 and the members 4, 5, 7, 8, 9, 10 in the vicinity thereof and occupies most of the sealing portion. In the illustrated form, the first sealing layer 11 is not exposed on the surface of the semiconductor module molding structure 100. The second sealing layer 13 covers the surface of the first sealing layer and constitutes the outer peripheral portion of the semiconductor module molded structure 100.

  The 2nd sealing layer 13 consists of a heat resistant resin composition explained in full detail in the said 1st Embodiment. By using the second sealing layer 13 as a heat resistant resin composition, it is possible to prevent cracks from occurring in the outer peripheral portion of the semiconductor module molded structure 100, and to prevent deformation of the outer peripheral portion and the like. A highly reliable semiconductor device can be provided. It consists of a heat resistant resin composition.

  The resin constituting the first sealing layer 11 is a thermosetting resin. Such a resin can be determined in relation to the heat-resistant resin composition described in detail above. That is, the resin constituting the first sealing layer 11 has a difference in thermal expansion coefficient within ± 10 ppm / ° C. with respect to the cured product of the heat resistant resin composition constituting the second sealing layer 13. preferable. This is to reduce the thermal stress after sealing. Further, the resin constituting the first sealing layer 11 preferably has an adhesive strength with the resin constituting the second sealing layer 13 of 10 MPa or more. This is to prevent cracks from entering the interface between the first sealing layer 11 and the second sealing layer 13 after sealing. As long as these conditions are satisfied, the type of resin constituting the first sealing layer 11 is not limited and may be an epoxy resin, a polyamide resin, or the like that is usually used for resin sealing of a semiconductor device. The resin constituting the first sealing layer 11 is also heat resistant according to the first embodiment in the same manner as the resin constituting the second sealing layer 13 as long as it satisfies the above-mentioned thermal expansion coefficient characteristics and adhesive characteristics. It may be a resin composition.

  In the semiconductor module molding structure 100 according to the first embodiment shown in the figure, the surface of the first copper block 2 opposite to the insulating layer 1, that is, the lower surface in the drawing is in contact with the second sealing layer 13. Although it is a form which is covered with the second sealing layer 13 and does not come into contact with the outside, the present invention is not limited to such a form. A part or the whole of the lower surface of the first copper block 2 may be exposed and connected to a cooling member or the like (not shown). FIG. 1 is a conceptual diagram, and the positional relationship between the first sealing layer, the second sealing layer, and the other members shown in the drawings is not necessarily as shown in the drawing. Furthermore, the configuration of the insulating substrate 4, the printed circuit board 9, and the implant pin 8 is not limited to the illustrated form.

  Next, the semiconductor module molded structure 100 according to the second embodiment will be described from the viewpoint of its manufacturing method. The manufacturing method of the SiC power semiconductor module molded structure mainly includes a step of assembling a member to which the insulating substrate 4, the semiconductor element 6, and the printed board 9 are joined, and a step of resin-sealing the member.

  The process of assembling the member to which the insulating substrate 4, the semiconductor element 6, and the printed circuit board 9 are joined is performed by forming the insulating substrate 4 by thermocompression bonding the first copper block 2 and the second copper block 3 on both surfaces of the insulating layer 1. A step of mounting one or more SiC power semiconductor elements 6 on one surface of the insulating substrate 4 by the conductive bonding layer a5, and a surface of the SiC power semiconductor element 6 on the opposite side of the insulating substrate 4 from the conductive surface. A step of attaching an implant type printed circuit board 9 having an implant pin 8 by the bonding layer b7 and a step of connecting an external connection terminal 10 to the second copper block 3 and the printed circuit board 9 are included. About such an assembly process and the specification of the member to be used, etc., you may follow the normal method disclosed by a prior art. For example, each process described in Japanese Patent Application Laid-Open No. 2013-004729 and Japanese Patent Application Laid-Open No. 2012-191010 by the applicant can be applied.

  The resin sealing step includes the first sealing step of forming the first sealing layer 11 using a thermosetting resin, and the second sealing layer 13 using the heat resistant resin composition according to the first embodiment. A second sealing step to be formed.

  In the first sealing step, a member in which the insulating substrate 4, the semiconductor element 6, and the printed circuit board 9 are joined with the thermosetting resin 1 to be the first sealing layer 11 that has been degassed under reduced pressure in a usual manner in advance. Is sealed. Sealing is performed by molding into a predetermined shape by a molding method such as transfer molding, liquid transfer molding, or injection molding. Thereafter, the thermosetting resin is thermoset at a predetermined temperature and time condition, for example, at 100 to 180 ° C. for 1 to 10 minutes to form the first sealing layer 11 and complete the first sealing step. To do.

  In the second sealing step, the heat-resistant resin composition according to the first embodiment, which has been degassed by a conventional method in advance, is applied to at least a part of the outer periphery of the molded body obtained in the first sealing step. Then, it is coated so as to have a predetermined thickness by a method such as molding or potting. Thereafter, the heat-resistant resin composition is thermoset at a predetermined temperature and time conditions, for example, at 100 to 200 ° C. for 1 to 3 hours to form the second sealing layer 13, thereby forming the second sealing layer 13. Complete the sealing process. By these steps, a molded body having a resin sealing portion having a two-layer sealing structure can be obtained. Further, when the first sealing layer 11 of the molded body is formed, a hole for inserting the mounting bracket 12 is formed in the first sealing layer, and after the first sealing layer 11 and the second sealing layer 13 are cured. The semiconductor module molded structure 100 can be obtained by the step of inserting the mounting bracket 12 into the hole.

  According to the semiconductor module molded structure 100 and the manufacturing method thereof according to the second embodiment, particularly in a semiconductor device in which the use atmosphere is high temperature, for example, 175 ° C. or higher, the reliability of the semiconductor device is improved and the cost is reduced. can do.

  Hereinafter, the present invention will be described in more detail by way of examples. The following examples are illustrative of the present invention and are not intended to limit the present invention.

[Example 1]
10 parts by mass of glycidyl ether was mixed with 100 parts by mass of the alicyclic epoxy compound to obtain an epoxy resin composition. To this epoxy resin composition, an acid anhydride curing agent is added so as to have an equivalent ratio of 1.0 and mixed uniformly, then poured into a mold, and heated and cured at 120 ° C. for 2 hours and then at 180 ° C. for 2 hours. To obtain a cured product. The Tg of the cured product was determined by DSC. The compounds used are as follows.
Alicyclic epoxy compound: Celoxide 2021P (manufactured by Daicel Chemical Industries) Epoxy equivalent 137
Glycidyl ether: JER epoxy resin 825 (Mitsubishi Chemical Corporation) epoxy equivalent 175
Acid anhydride: Ricacid MH-700 (manufactured by Shin Nippon Rika Co., Ltd.) Acid anhydride equivalent 161

[Examples 2 and 3]
The cured products of Examples 2 and 3 were obtained in the same manner as Example 1 except that 25 parts by mass and 50 parts by mass of glycidyl ether were added to 100 parts by mass of the alicyclic epoxy compound.

[Examples 4 to 6]
Cured products of Examples 4 to 6 were obtained in the same manner as in Examples 1 to 3 except that the following compounds were used as glycidyl ether and acid anhydrides.
Glycidyl ether: EPICLON N-655-EXP-S (manufactured by DIC Corporation) Epoxy equivalent 196
Acid anhydride: HN-2200 (manufactured by Hitachi Chemical Co., Ltd.) Acid anhydride equivalent 166

[Comparative Examples 1 and 2]
In the same manner as in Examples 1 to 6, except that the alicyclic epoxy compound was mixed uniformly without adding the glycidyl ether to the alicyclic epoxy compound so that the equivalent ratio was 1.0. Cured products of Comparative Examples 1 and 2 were obtained. As an acid anhydride curing agent, the above-mentioned Ricacid MH-700 was used in Comparative Example 1, and the above-mentioned HN-2200 was used in Comparative Example 2.

  The results are shown in Table 1 below.

  The resin composition and the semiconductor device using the resin composition according to the present invention are useful in a semiconductor power module that operates at a high temperature and is configured using a semiconductor element such as SiC or GaN.

DESCRIPTION OF SYMBOLS 1 Insulating layer 2 1st copper block 3 2nd copper block 4 Insulating substrate 5 Conductive joining layer a
6 SiC semiconductor element 7 Conductive bonding layer b
8 Implant Pin 9 Implant Type Printed Circuit Board 10 External Connection Terminal 11 First Sealing Layer (Thermosetting Resin)
12 Mounting bracket 13 Second sealing layer (heat resistant resin)
100 Semiconductor module molding structure

Claims (6)

A glycidyl ether selected from 3 ', 4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, bisphenol A diglycidyl ether or cresol novolac-type diglycidyl ether, and an acid anhydride curing agent. A heat resistant resin composition for sealing an SiC semiconductor element ,
A heat-resistant resin composition comprising 25 to 50 parts by mass of the glycidyl ether with respect to 100 parts by mass of the 3 ′, 4′-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate.   2. The heat resistant resin according to claim 1, further comprising an inorganic filler having an average particle diameter of 1 to 100 nm, wherein the inorganic filler is contained in an amount of 60 to 90% by mass with respect to 100% by mass of the entire heat resistant resin composition. Composition. Claim 1 or a heat-resistant resin composition a resin cured product obtained by curing a according to any one of 2. The resin cured product according to claim 3 , wherein the glass transition temperature is 220 ° C or higher. A member including a semiconductor element, an insulating substrate bonded to one surface of the semiconductor element, and a printed circuit board for connection to an external circuit bonded to the other surface of the semiconductor element is sealed with a sealing material. A semiconductor device comprising a molded body,
The sealing material is
A first sealing layer that covers the semiconductor element and is provided in a region adjacent to the semiconductor element, the first sealing layer made of a thermosetting resin;
It is a 2nd sealing layer which consists of a heat-resistant resin composition in any one of Claim 1 or 2 , Comprising: The said 1st sealing layer and at least one part of the outer surface of the said molded object A semiconductor device comprising a second sealing layer to be formed. The semiconductor device according to claim 5 , wherein the semiconductor element is a SiC semiconductor element.

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