JPH0459332B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a liquid epoxy resin encapsulant used for encapsulating semiconductor elements. [Conventional technology] The trend toward lower costs and higher integration in semiconductor packaging, including ICs and LSIs, has shifted from DIP (dual in-line package) using conventional transfer molding to HIC (hybrid IC) and COB (chip-on). board) and PPGA (plastic pin grid array), which require spot sealing with resin. In these new mounting forms, the reliability of the encapsulated element is greatly affected by the performance of the resin encapsulant itself, such as moisture resistance and electrical corrosion resistance. Recently, the mounting form described above has been increasingly used in high-grade devices, and on the premise that the moisture resistance and electrical corrosion resistance mentioned above are sufficient, it is also required that the mounting form is equivalent to that of transfer molded products. Resin encapsulants are now required to have extremely high heat cycle resistance. On the other hand, in the bonding of semiconductor elements, wireless bonding is increasingly replacing wire bonding, which has been the mainstream in the past. Wireless bonding is, for example, a technique called gigantic bonding or flip chip, in which a semiconductor element and a substrate are electrically bonded using bumps (protruding electrodes). In bonding using bumps, especially bonding using solder bumps, if unsealed, defects will occur in the bumps in a heat cycle test. In order to prevent this, various attempts have been made, such as those listed below [Hatada: Latest Technical Trends in Wireless Bonding, Monthly Semiconductor World, Vol. 6, No. 10 (September 1987), pp. 84-92]. Stress is absorbed by interposing conductive rubber or conductive adhesive between the pads of the semiconductor element and the solder bumps and/or between the solder bumps and the pads of the substrate. Stack multiple bumps to absorb stress. Reinforce only the area around the bump with resin. A photocurable resin is filled between the circuit surface of the semiconductor element and the circuit surface of the substrate and cured, and the shrinkage stress caused by this curing causes the electrodes of the semiconductor element and the electrodes of the substrate to be pressed together via bumps (instead of adhesion). ). [Problems to be Solved by the Invention] Conventional epoxy resin compositions using amine curing agents have high hygroscopicity and poor moisture resistance reliability, and it has also been difficult to obtain electrical corrosion resistance. Therefore, various resin sealing materials have been developed in order to meet the various market needs described above, but these have not yet met the requirements. For example, an epoxy resin composition using a compound having one acid anhydride group in one molecule, such as methylhexahydrophthalic anhydride (MHHPA), as a curing agent has extremely high electrical corrosion resistance. However, it was not possible to obtain heat cycle resistance on the level of transfer molded products. On the other hand, when wireless bonding is used as described above, moisture resistance reliability can be improved,
In order to prevent impurity ions from entering, it is necessary to seal or seal the entire semiconductor element. On the other hand, as shown in FIG. 3, a method has been proposed in which the space between the circuit surface of the semiconductor element 1 and the circuit surface of the substrate 2 is completely filled with a liquid epoxy resin sealing material 5 for sealing. With this sealing method, concentrated stress on the bumps 3 can also be dispersed by resin reinforcement. To achieve such sealing, for example, the fourth
As shown in Figures a and b, a liquid epoxy resin encapsulant 5 is delivered to the side of a pair of opposite sides of the semiconductor element 1, and the encapsulant 5 enters and fills the space between the element 1 and the substrate 2. . The liquid resin sealing material used in this sealing method must be able to achieve high reliability, have a low viscosity, and have good penetration into a narrow space of, for example, several tens of micrometers. As the substrate 2, for example, a film such as a polyimide film, an organic printed wiring board, a metal plate, a ceramic substrate, etc. are used. In view of the above, the present invention provides a liquid epoxy resin sealing material that can be used for spot sealing and has excellent moisture resistance, electrical corrosion resistance, and heat cycle resistance. The task is to do so. [Means for Solving the Problems] In order to solve the above problems, the liquid epoxy resin encapsulant according to the present invention contains the following components (a), (b), and (c).
and (d) as essential components, and the molar ratio of the epoxy groups in component (a) to the total acid anhydride groups in component (b) is
It is characterized by being 10/6 to 10/9. (a) Bisphenol A with an epoxy equivalent of 175 or less
mold epoxy resin. (b) methyltetrahydrophthalic anhydride and/or
or a monofunctional acid anhydride consisting of methylhexahydrophthalic anhydride and 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic acid anhydride and/or A curing agent formed by using together a polyfunctional acid anhydride consisting of glycerol trisanhydrotrimellitate, wherein an acid anhydride group in the monofunctional acid anhydride and an acid anhydride in the polyfunctional acid anhydride are used together. An acid anhydride curing agent having a molar ratio of 4/6 to 8/2. (c) Curing accelerator. (d) Filler. [Function] The liquid epoxy resin encapsulant of the present invention uses a monofunctional acid anhydride and a polyfunctional acid anhydride together as a curing agent. The polyfunctional acid hydride acts as a diluent and suppresses the heat cycle resistance of the monofunctional acid anhydride, and the polyfunctional acid hydride compensates for the lack of heat cycle resistance of the monofunctional acid anhydride, creating a liquid epoxy resin encapsulant with excellent heat cycle resistance. This is considered to be what can be obtained. [Example] The epoxy resin used in this invention is a bisphenol A type epoxy resin having an epoxy equivalent of 175 or less in order to reduce the viscosity of the sealing material and reduce impurity ions. Among these, those containing diglycidyl ether of bisphenol A as a main component are preferred. The monofunctional acid anhydride used in this invention is at least one of methyltetrahydrophthalic anhydride (MTHPA) and methylhexahydrophthalic anhydride (MHHPA). The polyfunctional acid anhydride used in this invention has the following formula (): 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride [hereinafter referred to as "compound ()]" and the following formula ( ): It is at least one type of glycerol trisanhydrotrimellitate (hereinafter referred to as "compound ()") represented by: This is thought to be because heat cycle resistance depends not only on the heat resistance of the resin but also on the hardness after curing, but this is not clear. Further, among the above two compounds () and (), compound () has better moisture resistance reliability and is particularly preferable. this is,
This is thought to be because the ester group in the molecule of compound () is susceptible to hydrolysis. In addition to moisture-resistance reliability, electrical corrosion resistance, and heat cycle resistance, resin encapsulants also have process control characteristics that lead to process costs, such as being liquid, easy to handle, and having a long curing time. Characteristics that are not required may also be required. Epoxy resin encapsulants that use only polyfunctional acid anhydrides as curing agents can achieve excellent heat cycle resistance, but this compound is solid at room temperature,
Therefore, the obtained epoxy resin sealing material has a very high viscosity at room temperature and can hardly be called liquid, making it difficult to meet such demands. However, in this invention,
Since a monofunctional acid anhydride and a polyfunctional acid anhydride are used together as a curing agent, it is easy to meet such requirements. The blending ratio of the monofunctional acid anhydride and the polyfunctional acid anhydride is determined by considering the following points: Number of moles of acid anhydride groups in polyfunctional acid anhydride = 4:6
The two are blended in a ratio of ~8:2.
If the amount of the polyfunctional acid anhydride is less than this molar ratio range, the heat resistance temperature of the cured product will not be sufficiently high, and the heat cycle resistance effect of the polyfunctional acid anhydride may be weakened. On the other hand, if the polyfunctional acid anhydride is in excess of the molar ratio range, the viscosity of the encapsulant may increase, making it unsuitable for use as a liquid material. In particular, as described below, when a polyfunctional acid anhydride is dissolved in a monofunctional acid anhydride, if the polyfunctional acid anhydride is in excess, the viscosity of the sealant becomes so high that it becomes unsuitable for entering and filling narrow spaces. Furthermore, there is a possibility that the polyfunctional acid anhydride may precipitate as a solid during storage. Note that the acid anhydride group (acid anhydride group) is represented by the following formula. Regarding the blending ratio of these monofunctional acid anhydrides and polyfunctional acid anhydrides to the above epoxy resin, if we focus only on heat cycle resistance, from the viewpoint of stoichiometry, the epoxy group mole in the epoxy resin is Number: Number of moles of acid anhydride groups in total acid anhydride = approximately 1:
Ideally, the molar ratio is 1 (molar ratio). but,
As a sealing material, if moisture resistance and reliability are taken into consideration,
The number of moles of epoxy groups in the epoxy resin: the number of moles of acid anhydride groups in the total acid anhydride is within the range of 10:6 to 10:9. Although not intended to be particularly limiting, the range of 10:7 to 10:8 is particularly preferred among the above ranges. This is because when the molar ratio of acid anhydride groups is lower than 10:6, the glass transition temperature (Tg) of the cured product decreases.
is significantly lowered, the heat resistance temperature is lowered, and there is a possibility that not only the heat cycle resistance will deteriorate but also the moisture resistance reliability will be adversely affected. Furthermore, if the molar ratio of acid anhydride groups exceeds 10:9, the moisture resistance reliability may be extremely deteriorated. This is thought to be caused by free carboxyl groups remaining in the cured product, but it is not clear. The polyfunctional acid anhydride may be blended into the epoxy resin in a mixed state with the monofunctional acid anhydride, or may be blended into the epoxy resin separately. When a polyfunctional acid anhydride and a monofunctional acid anhydride are separately blended, the solid polyfunctional acid anhydride may be dispersed in the components as a powder. In the liquid epoxy resin encapsulant of the present invention, polyfunctional acid anhydride is replaced with liquid monofunctional acid anhydride in order to minimize the amount of solids such as powder in the material in order to penetrate and fill narrow gaps. It is preferable to use it by dissolving it. Such liquid monofunctional acid anhydrides are liquid at around room temperature.
Using one or both of MTHPA and MHHPA. The polyfunctional acid anhydride is not particularly limited, but for example, the cured product of the epoxy resin composition has excellent moisture resistance, the cured product has a high glass transition temperature (Tg), It is preferable to use the compound (2) for three reasons: it has excellent heat cycle properties. The liquid epoxy resin encapsulant of the present invention is either one-component or two-component depending on whether the curing accelerator described below is for one-component or two-component use. If the epoxy resin encapsulant is a one-component type, if a polyfunctional acid anhydride is dissolved in a monofunctional acid anhydride and blended into the epoxy resin, the viscosity of the material will be extremely high and its pot life will be significantly shortened. This problem arises. Therefore, in the case of one-component,
Preferably, the polyfunctional acid anhydride is dispersed in the components as a powder as described above. If the epoxy resin sealant is a two-component type,
Since the acid anhydride and the epoxy resin are supplied separately and such a problem can be avoided, the blending form of the polyfunctional acid anhydride and monofunctional acid anhydride may be either of the above two. In addition, in this invention, as a monofunctional acid anhydride,
Using at least one of MTHPA and MHHPA and using the compound () as a polyfunctional trianhydride,
When the latter is dissolved in the former, a two-component composition must be used. In other words, the main agent containing epoxy resin and the compound () are combined with MTHPA and/or
Alternatively, it is separated into a curing agent dissolved in MHHPA, and mixed at a predetermined ratio immediately before use. This is because when the compound () is dissolved in MTHPA and/or MHHPA and mixed with an epoxy resin, the viscosity of the mixture increases over time even without a curing accelerator. In this invention, when the composition is a two-component type, if a high-purity epoxy with an epoxy equivalent of 175 or less is used as the epoxy resin, crystallization may occur easily due to the narrow molecular weight distribution. In order to prevent this crystallization, it is preferable to add at least one monofunctional acid anhydride to the main ingredient. In this case, for the above-mentioned reasons, the polyfunctional acid anhydride should not be dissolved in the monofunctional acid anhydride. The types of curing accelerators that help the curing reaction of epoxy resin by acid anhydride compounds as described above are as follows:
The present invention is not particularly limited, and compounds that are normally used in the above-mentioned curing reaction can be used. That is, tertiary amines or their salts, triazoles or their salts, imidazoles or their salts, organometallic complex salts, organic acid metal salts, quaternary ammonium salts, phosphines, phosphonium salts, diazabicycloalkenes, or Known salts thereof may be used alone or in combination of two or more. As mentioned above, these curing accelerators are usually supplied as a one-part type or a two-part type, but either type may be used. In addition, from the viewpoint of excellent moisture resistance, it is preferable to use diazabicycloundecene (DBU) salt as the curing accelerator. There are no particular limitations on the DBU salt as long as it consists of a DBU cation and a counteranion.
For example, DBU-phenol novolak resin salt,
DBU-octylate, DBU-borate, DBU
Various salts are on the market, including -phthalate, DBU-toluenesulfonate, etc. these
One type of DBU salt may be used alone, or two or more types may be used in combination, or
DBU salt and other curing accelerators may be used in combination. The same applies to the type of filler, and general fillers used for epoxy resins can be used. That is, fused silica, crystalline silica,
Talc, calcium carbonate, etc. can be used. These fillers can be used alone or in combination. Further, fillers other than these can be used as long as they have a low content of free ions and hydrolyzable halogens that adversely affect moisture resistance reliability. In addition, in this invention, the filler has an average particle size of
The filler content of the liquid epoxy resin sealing material is 10 to 60% by weight. % is preferable.
If the average particle size of the filler is larger than 10 μm, or if the total filler contains more than 1% by weight of particles with a particle size of 50 μm or more, it is difficult to penetrate into narrow gaps. If the filler content of the liquid epoxy resin sealant exceeds 60% by weight, the viscosity of the material will become too high, making it difficult to penetrate into narrow gaps.
If it is less than % by weight, the coefficient of linear expansion and moisture absorption of the material will increase, making it unsuitable for sealing semiconductor devices. As shown in FIG.
Suitable for sealing etc. Element 1 and substrate 2
The distance A between the two is, for example, about 20 to 100 μm, and such a gap can also be filled. Board 2
For example, those mentioned above are used. The liquid epoxy resin encapsulant of the present invention can be a one-component composition, as long as the above-mentioned essential components are finally mixed, dispersed, or kneaded.
The form in which it is supplied, such as a two-component composition, is not particularly limited. In this invention, among the various additives that are normally added to liquid epoxy resin sealants, substances that do not contradict the purpose of this invention may be added in amounts that do not impede the effects. Examples of such additives include pigments, diluents, coupling agents, leveling agents, antifoaming agents, ion trapping agents, and the like. Examples of pigments include commonly used pigments such as carbon black, red iron oxide, and titanium white. Examples of the diluent include phenyl glycidyl ether. As a coupling agent,
Examples include silane coupling agents. In the present invention, the pigment preferably has an average particle size of 1 μm or less and is dispersed in the epoxy resin in order to allow the composition to enter and fill narrow gaps. Next, specific examples of the present invention will be described together with comparative examples. In the following Examples and Comparative Examples, when the curing accelerator was one-component, each necessary component was dispersed and mixed using Homo Disper (manufactured by Tokushu Kika Kogyo Co., Ltd.). In addition, when the curing accelerator is a two-component type, the curing accelerator and acid anhydride are dispersed and mixed using a homodisper to form liquid B, and the epoxy resin and the remaining components are dispersed and mixed. After making it into a liquid,
Immediately before sealing, both solutions A and B were mixed in the required ratio using a homodisper and used. Examples 1 to 3, Comparative Examples 1 and 2 As the epoxy resin, bisphenol A type epoxy resin (YD8125 manufactured by Toto Kasei Co., Ltd., epoxy equivalent
175) as a filler, fused silica (Y-40 manufactured by Ryumori Co., Ltd., average particle size 8 μm), and diazabicycloundecene octylate (San-Apro), a two-component curing accelerator, as a curing accelerator. Manufactured by U- Co., Ltd.
CAT SA102] and the acid anhydrides shown in Table 1 as curing agents to prepare two-component liquid epoxy resin encapsulants. The mixing ratio of each component is such that the number of moles of epoxy groups in the epoxy resin: the number of moles of acid anhydride groups in the total acid anhydride = 10:8, and the curing accelerator is
1 PHR (ratio of 1 part by weight to 100 parts by weight of epoxy resin), the filler was 60% by weight of the total composition. The abbreviations in Table 1 represent the following acid anhydrides. MHHPA: Methylhexahydrophthalic anhydride [Epiclon B-650 manufactured by Dainippon Ink Chemical Co., Ltd., acid anhydride equivalent 168] MTHPA: Methyltetrahydrophthalic anhydride [Epiclon B-570 manufactured by Dainippon Ink Chemical Co., Ltd. , acid anhydride equivalent 166] B4400: 5-(2,5-dioxotetrahydro-
3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride [Epiclon B-4400, manufactured by Dainippon Ink Chemical Co., Ltd., acid anhydride equivalent weight 132] TMTA-C: Glycerol trianhydrotri Meritate [TMTA-C manufactured by Shin Nihon Rika Co., Ltd.
Acid anhydride equivalent: 205] As shown in Figure 1, a semiconductor element [C-MOS, 2000 gate LSI] mounted on a PPGA substrate 2
(4 mm square)] 1 was sealed with the liquid epoxy resin sealing material 5 of each example, and cured under the curing conditions of 120° C. for 1 hour + 160° C. for 3 hours, and used as a sample. <Heat cycle resistance test> This sample was subjected to a heat cycle of -65℃ atmosphere for 30 minutes → room temperature for 5 minutes → 150℃ atmosphere for 30 minutes → room temperature for 5 minutes. The number of elements (out of 10 total samples) was investigated. The results are shown in Table 1.

[Table] (Note) 〓%〓 is 〓weight%〓.
From the results in Table 1, it was found that all of Examples 1 to 3, which are epoxy resin compositions of the present invention, had improved heat cycle resistance compared to Comparative Examples 1 and 2. Examples 4 to 11 A liquid epoxy resin encapsulant was prepared with the ingredient combination shown in Table 2, and an element was encapsulated as shown in Fig. 1 in the same manner as in the previous Examples and Comparative Examples, and used as a sample. . The obtained samples were subjected to a moisture resistance reliability test, an electrical corrosion resistance test, and the heat cycle resistance test described above to evaluate the resin sealant.
In addition, these epoxy resin encapsulants cured at 120°C for 1 hour + 160°C for 3 hours were measured using a viscoelastic spectrometer, and the temperature at the tanδ peak was determined to be the glass transition temperature (Tg). did. The moisture resistance reliability test and the electrical corrosion resistance test were conducted as follows. <Moisture-resistance reliability test> We performed the so-called Pressure Cutting Car Test (PCT) in which each sample was left in a saturated steam atmosphere at 2 atm and 121°C, and the number of non-defective devices (out of 10 samples) after a specified period of time was determined. Examined. <Electrical Corrosion Resistance Test> A so-called THB test is conducted in which a device is left in an atmosphere of 85°C and 85% relative humidity with a driving voltage applied to it, and the number of non-defective devices (out of 10 samples) after a predetermined period of time is determined. Examined. The above results are shown in Table 3. In addition, each abbreviation in Table 2 is according to the previous Table 1,
Abbreviations not shown in Table 1 represent the following compounds. The same filler as in Examples 1 to 3 was used. 2MA-OK: 2,4-diamino-6 [2'-methylimidazolyl-(1')] ethyl-s-triazine isocyanuric acid adduct [1-component curing accelerator, manufactured by Shikoku Kasei Kogyo Co., Ltd. 2MA-OK ]

【table】

[Table] From the results in Table 3, it can be seen that Examples 4 to 11 all have high heat cycle resistance. In addition, among these examples, when the blending ratio of the polyfunctional acid anhydride is 2/8 or more (polyfunctional acid anhydride/monofunctional acid anhydride = 2/8 or more in terms of the molar ratio of the acid anhydride group), the resistance is even higher. It can also be seen that it has excellent heat cycle properties. Looking at the epoxy equivalent (number of moles of acid anhydride groups/number of moles of epoxy group), which represents the molar ratio of acid anhydride groups to epoxy groups, moisture resistance reliability is high when the epoxy equivalent is 0.9 or less, and heat cycle resistance is 0.6 or more. Products with excellent properties are obtained. Therefore, it can be seen that a range of epoxy equivalent of 0.9 to 0.6 is a preferable range for these two inventions. Example 12 Bisphenol A type epoxy resin [YD8125 manufactured by Toto Kasei Co., Ltd., epoxy equivalent]
175] as a filler, fused silica [Y-40 manufactured by Ryumori Co., Ltd., average particle size 8 μm], and an amine hardening accelerator [PN- manufactured by Ajinomoto Co., Ltd.] as a hardening accelerator.
23] respectively, and the curing agent MHHPA
(monofunctional acid anhydride) and B-4400 (polyfunctional acid anhydride)
Liquid epoxy resin encapsulants were prepared by varying the ratio of The mixing ratio of each component is that the molar ratio of the epoxy group in the epoxy resin to the acid anhydride group in the acid anhydride is 10:8, and the curing accelerator is 3PHR (3 parts by weight per 100 parts by weight of the epoxy resin). The filler was 60% by weight of the total composition. The material viscosity of the obtained liquid epoxy resin sealant and the glass transition temperature (Tg) of the cured product were measured. The results are shown in Figure 2. From the results shown in Figure 2, when the equivalent ratio (=MHHPA equivalent/B-4400 equivalent) representing the ratio of monofunctional acid anhydride to polyfunctional acid anhydride becomes smaller than 4/6, the material viscosity will decrease to 1 million cp. It was found that this greatly exceeded the limit, making it difficult to use as a liquid material. In addition, the glass transition temperature of the cured product is at an equivalence ratio of 4/6.
It was also found that the material has a heat resistance temperature of 185°C, which is sufficient for use as a material for semiconductor encapsulation. Examples 13 to 19 Each component was mixed according to the formulation shown in Table 4 to obtain a liquid epoxy resin encapsulant. Bisphenol A type epoxy resin [YD8125 manufactured by Toto Kasei Co., Ltd., epoxy equivalent]
172], the above-mentioned Epiclon B-570 and Epiclon B-650 as monofunctional acid anhydrides, the above-mentioned Epiclon B-4400 as a polyfunctional acid anhydride, and the above-mentioned U-CATSA102 as a curing accelerator. there was. The filler was fused silica [RD-8 manufactured by Tatsumori Co., Ltd.
Average particle size 15 μm, proportion of particles of 50 μm or more 7% by weight], fused silica [Y-40 handled by Ryumori Co., Ltd., average particle size
8μm, proportion of particles of 50μm or more 0.9% by weight] and fused silica [ZA-30 handled by Tatsumori Co., Ltd., average particle size
5 μm, 0.5% by weight of particles larger than 50 μm] were classified to have a predetermined particle size distribution, and mixed as appropriate for use. Using each epoxy resin sealant, the narrow space penetration and viscosity were investigated as follows, and the results are shown in Table 4. <Narrow space penetration> As shown in FIG. 5, 20 μm thick stainless steel foil 14 is placed on the slide glass 12 at appropriate intervals, and the cover glass 1 is placed across the slide glass 12.
1 was placed and fixed with adhesive tape 16. A liquid epoxy resin sealant was applied to one side of the 20 μm thick gap between the cover glass 11 and the slide glass 12, and after heating at 100° C. for 1 hour, the degree of penetration was visually observed. The degree of evaluation was evaluated in three stages: good (○), slightly poor (△), and poor (×), and the results are shown in Table 4. The viscosity of each liquid epoxy resin encapsulant (the viscosity after mixing the main resin and curing agent) was measured using a Bruckfield B-type viscometer using an SC rotor at 25°C.
Measured at 50 rpm.

【table】

[Table] As shown in Table 4, the polyfunctional acid anhydride is dissolved in the monofunctional acid anhydride, and the filler has an average particle size of
It can be seen that narrow space penetration is good when the particle size is 10 μm or less and the filler contains 1% by weight or less of particles with a particle size of 50 μm or more. Also, the proportion of total filler is
If it exceeds 60% by weight of the entire sealing material, the viscosity will be too high and the ability to penetrate into narrow spaces will deteriorate. Examples 20 to 26 Each component was mixed according to the formulation shown in Table 5, and Example 13
A liquid epoxy resin encapsulant was obtained in the same manner as in 19. Epoxy resin, acid anhydride and curing accelerator are
In both cases, the same materials as those used in Examples 13 to 19 were used. As the filler, the above-mentioned ZA-30 was used in an amount of 50% by weight based on the entire composition. The viscosity and narrow-part penetration properties of each liquid epoxy resin sealant were investigated in the same manner as in Examples 13 to 19, and the results are shown in Table 5. Further, the following moisture resistance reliability test was conducted using each epoxy resin sealing material, and the results are shown in Table 5. <Moisture resistance reliability test> As shown in Figure 6, semiconductor elements (C-MOS,
A 4 mm square LSI chip (2000 gates) 1 was mounted on the bottom of the cavity 29 of the plastic PGA board 22. Thereafter, the semiconductor element 1 was covered with a liquid epoxy resin composition 5, and sealed by curing at 100° C. for 1 hour and 160° C. for 3 hours, and a sample was obtained. Note that 27 is a bonding wire. Each sample was subjected to PCT at a saturated water vapor pressure of 2 atm.
We investigated the cumulative number of defects over the course of processing time. The number of samples was 10 for each epoxy resin sealant.

【table】

〔Effect of the invention〕

The liquid epoxy resin sealing material according to this invention is
Since a monofunctional acid anhydride and a polyfunctional acid anhydride are used together as a curing agent, it can be used for spot sealing, and has excellent moisture resistance, electrical corrosion resistance, and heat cycle resistance. It is also excellent.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram illustrating the sealed state of test elements used in Examples and Comparative Examples in order to understand the effect of the invention of claim 1, and Fig. 2 is an explanatory diagram illustrating the sealed state of a test element used in Examples and Comparative Examples. A graph showing the relationship between the ratio of anhydride, the viscosity of the epoxy resin encapsulant, and the glass transition temperature of the cured product. Figure 3 shows a portion of the sealing between the bump-bonded semiconductor element and the substrate. The side sectional view, Figures 4a and 4b, show the state of the part immediately before filling with the epoxy resin sealant, Figure a is the side sectional view, Figure b is the plan view, and Figure 5 examines the ability to penetrate into narrow spaces. FIG. 6 is a partially sectional side view showing a state in which a wire-bonded semiconductor element is sealed. 5...Liquid epoxy resin sealant.

Claims (1)

[Claims] 1. Contains the following components (a), (b), (c) and (d) as essential components, including an epoxy group in component (a) and all acid anhydrides in component (b). A liquid epoxy resin encapsulant having a molar ratio of 10/6 to 10/9. (a) Bisphenol A with an epoxy equivalent of 175 or less
mold epoxy resin. (b) methyltetrahydrophthalic anhydride and/or
or a monofunctional acid anhydride consisting of methylhexahydrophthalic anhydride and 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic acid anhydride and/or A curing agent formed by using together a polyfunctional acid anhydride consisting of glycerol trisanhydrotrimellitate, wherein an acid anhydride group in the monofunctional acid anhydride and an acid anhydride in the polyfunctional acid anhydride are used together. An acid anhydride curing agent having a molar ratio of 4/6 to 8/2. (c) Curing accelerator. (d) Filler. 2. The acid anhydride curing agent is a monofunctional acid anhydride and a polyfunctional acid anhydride dissolved to form a solid-free mixture, and the filler is a silica filler that covers the entire encapsulant. It accounts for 10-60% by weight, and
The liquid epoxy resin encapsulant according to claim 1, wherein the proportion of particles having a particle size of 50 μm or more in the silica filler is 1% by weight or less, and the average particle size of the silica filler is 10 μm or less.