JPS62199612A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain a composition outstanding in heat cycle, heat and moisture resistances, useful for semiconductor sealing, by modification reaction between a specific fluororesin and silane coupling agent followed by incorporating inorganic filler and polyfunctional epoxy resin. CONSTITUTION:The objective composition can be obtained by blending (I) a reaction product from modification reaction between (A) a OH group-contg. fluororesin (pref. with a OH value 10-160mg/KOH/g) and (B) a silane coupling agent of formula (Y is monovalent organic acid containing phenyl, epoxy and amino groups, R is H or 1-6C alkyl; R1 is phenyl, methyl or ethyl; n is 2 or 3) and (II) inorganic filler followed by incorporation of (III) a polyfunctional epoxy resin and/or phenol novolak resin and (IV) a curing promotor. Preferably, the weight ratio A/B is 0.2-4.0, the amount of the component B being 0.5-3.0 pts.wt. per 300pts.wt. of the component II.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention involves mixing a modified reaction product obtained by subjecting an OH group-containing fluororesin and a silane coupling agent to a modification reaction with an inorganic filler, and then mixing the mixture with an inorganic filler. To provide an epoxy resin composition for semiconductor encapsulation that is blended with a functionalized boxy resin and has excellent heat cycle resistance, moisture resistance, and heat resistance.

[Conventional techniques and their problems] At present, resin encapsulation methods are widely used to encapsulate semiconductor elements such as ICs and LSIs using silicone resins or epoxy resins, and among these, epoxy resins are relatively superior. It is widely used as a resin for semiconductor encapsulation because it provides airtightness and is inexpensive.

However, when large-capacity semiconductor devices are encapsulated using this epoxy resin system, bonding wires of the device may be damaged due to stress caused by shrinkage during curing or stress caused by the difference in expansion coefficient between internal elements and the epoxy resin system. This may cause deformation, wire breakage, or cracks in the device passivation. Therefore, in order to reduce these stresses, methods such as adding a flexibility imparting agent to the epoxy matrix or increasing the number of inorganic fillers added to reduce the expansion coefficient are being considered.

However, the addition of a flexibility-imparting agent has the disadvantage that it lowers the glass transition temperature of the cured resin and also causes a decrease in electrical properties and moisture resistance in a high temperature range, resulting in unfavorable results.

On the other hand, in order to increase the amount of inorganic filler added and reduce the expansion coefficient, it is necessary to add the amount of 80% by weight or more, but in this case, the melt viscosity of the resin composition increases and the fluidity decreases significantly. Therefore, high-pressure molding is required when sealing the device. Furthermore, the increase in melt viscosity causes wire flow and wire breakage during molding, resulting in unfavorable conditions.

[Problems to be Solved by the Invention] The present invention has been made in order to solve these problems, and has heat cycle resistance, heat resistance, and moisture resistance that do not damage the element due to the stress caused by the sealing material. The purpose of the present invention is to provide an epoxy resin composition for semiconductor encapsulation that has excellent properties and does not reduce workability in molding IC elements.

[Means for Solving the Problems] The present invention provides an OH group-containing fluororesin and a general formula (I): (wherein ■ is a monovalent organic group containing a phenyl group, an epoxy group or an amino group, and R is a monovalent organic group containing a phenyl group, an epoxy group or an amino group; An inorganic filler is obtained by subjecting a modified reaction product to a modification reaction with a silane coupling agent represented by a hydrogen atom or an alkyl group of 1 to 6, R1 is a phenyl group, methyl group, or ethyl group, and n is 2 or 3. The present invention relates to an epoxy resin composition for semiconductor encapsulation, characterized in that the mixture is mixed with a polyfunctional epoxy resin and/or a phenol novolac resin, and a curing accelerator.

[Operations and Examples] The modified reaction product into which a functional group capable of reacting with an inorganic filler is introduced is a fluororesin containing an OH group, which is generally known as a low hygroscopic material with excellent thermal stability, and a silane coupling agent. It is obtained by a denaturation reaction with

By mixing the modified reaction product and the inorganic filler, a resin layer is formed on the surface of the inorganic filler, and when mixed with the curing accelerator and the epoxy resin matrix, the stress that occurs when the mixture is cured is significantly reduced. Furthermore, since it provides a low elastic modulus and a low moisture absorption rate without substantially lowering the glass transition temperature of the epoxy resin matrix, it is possible to use an epoxy resin composition with excellent heat resistance and moisture resistance.

The OH group-containing fluororesin used in the present invention includes tetrafluoroethylene or trifluorochloroethylene,
Copolymerized olefinic hydrocarbons having 2 to 5 carbon atoms and/or vinyl ether monomers and having a number average molecular weight of 500 to ioo, ooo can be used.

If the number average molecular weight is less than 500, the reduction in stress developed at the interface between the epoxy resin matrix and the inorganic filler will be small, and if it exceeds 100,000, the inorganic filler will agglomerate and the composition will melt. As the viscosity increases, workability decreases, and furthermore, the stress developed at the interface between the epoxy resin matrix and the inorganic filler is less reduced.

The flower value of 0■ group-containing fluororesin is 10 to 160 mg OH
/Q range is preferable, and the OH value is 10 mg and OH
/g, the modified reaction product obtained by modifying the OH group-containing fluororesin and the silane coupling agent has poor reactivity with the inorganic filler, and the OH value is 160111 (
JKQH/(When J is exceeded, thickening or gelation occurs in the denaturation reaction.

The silane coupling agent used in the present invention has a general formula (): % formula % (wherein, Y is a monovalent organic group containing a phenyl group, an epoxy group, or an amino group, and R is a hydrogen atom or a carbon number of 1 to 6 an alkyl group, R1 is a phenyl group, a methyl group, an ethyl group,
n represents 2 or 3).

Specific examples of the silane coupling agent include phenyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltribenoxysilane, γ-glycidoxypropyldimethylethoxysilane, and γ-glycidoxypropyltribenoxysilane. -Glycidoxypropylmethyljethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, etc., and these can be used alone. Alternatively, two or more types are used.

The modification reaction between an OH group-containing fluororesin and a silane coupling agent is usually carried out using, for example, xylene, toluene, acetone,
This is carried out in a solvent such as methyl ethyl ketone, ethyl acetate, tert-butyl alcohol, etc., and these solvents may be used alone or in combination of two or more.

The ratio of the amount A (parts (parts by weight, the same shall apply hereinafter)) of the OH group-containing fluororesin to the amount B (parts) of the silane coupling agent is A/B-0, 2 to 4.0. Preferably, the range is within the range. If A/B is less than 0.2, the reduction in stress developed at the interface between the epoxy resin matrix and inorganic filler will be small, and if it exceeds 4.0, agglomeration of the inorganic filler will occur, resulting in poor workability. Not only does this decrease, but the reduction in stress also decreases.

The amount of the silane coupling agent blended is preferably within the range of 0.5 to 3.0 parts based on 300 parts of the inorganic filler.

If the amount of the silane coupling agent is less than 0.5 part, a layer of epoxy resin matrix will not be sufficiently formed on the surface of the inorganic filler, which will adversely affect moisture resistance. If the amount exceeds 3.0 parts, the excess silane coupling agent increases hygroscopicity and adversely affects moisture resistance.

After the OH group-containing fluororesin and the silane coupling agent are subjected to a modification reaction, the resulting modification reaction product is mixed with an inorganic filler using a Henschel mixer (manufactured by Mitsui Miike Seisakusho) or the like. At this time, it is preferable that the blending IC (parts) of the modification reactant is within the range of C/D-0.002 to 0.04 relative to the blending amount D (parts) of the inorganic filler. When C/D is less than 0.002, the reduction in stress developed at the interface between the epoxy resin matrix and the inorganic filler becomes small;
If it exceeds this, agglomeration of the inorganic filler occurs, which not only reduces workability but also reduces the reduction in stress. Examples of the inorganic filler include crystalline silica powder, fused silica powder, alumina powder, talc, quartz glass powder, calcium carbonate powder, and glass fiber. 50~ for epoxy resin composition
It is preferable to add 80% (weight %, the same applies hereinafter).

If it is less than 50%, the coefficient of linear expansion and curing stress cannot be lowered sufficiently, causing problems such as cracks in the IC element, and if it exceeds 80%, fluidity decreases, causing problems in workability. Therefore, a blending amount of 1 to 1 lliL is suitably used depending on the required properties within the range of 50 to 80%.

As the polyfunctional epoxy resin used in the present invention, various types of epoxy resins having an epoxy equivalent of 75 to 250 can be used, such as novolak epoxy resin, bisphenol A epoxy resin, and alicyclic epoxy resin. Among these, it is preferable to use novolak-based epoxy resins, which have particularly excellent high-temperature properties. Further, these epoxy resins may be used alone or in combination of two or more. In addition to these epoxy resins, epoxy resins such as brominated novolac epoxy resins and brominated bisphenol A epoxy resins can be used in combination, if necessary.

The phenolic novolac resin used in the present invention can be obtained by subjecting a phenolic compound such as phenol, cresol, xylenol, bisphenol A lursorcin, etc., to a condensation reaction with formaldehyde or paraformaldehyde under an acidic catalyst. The content of unreacted compounds in the obtained phenol novolac resin is preferably 0.5% or less from the viewpoint of moisture resistance and heat resistance of the IC device.

Examples of the curing accelerator used in the present invention include 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, and 2-undecylimidazole. imidazole compounds such as
2-(dimethylaminomethyl)phenol, 2.4.6
- Tris(dimethylaminomethyl)phenol, benzyldimethylamine, α-methylbenzyldimethylamine, veridine, dimethyllaurylamine, dialkylaminomethanolamine, tetramethylguanidine, 2
-dimethylamino -2-humanOxibOpan,N,N
-dimethylpiperazine, N-methylmorpholine, piperazine, 2-(dimethylaminomethyl)phenol, hexamethylenetetramine, 1-hydroxylethyl-2-
Examples include tertiary amines such as heptadecylglyoxalidine and 1,8-diazabicyclo(5,4,0)undecene-7, and other amine compounds and imidazole compounds.

In addition, when used, colorants such as carbon black, mold release agents such as carnauba wax and polyethylene wax, flame retardants such as antimony trioxide, and coupling agents such as γ-glycidoxypropyltrimethoxysilane are added. Good too.

The various components are mixed using a commonly used mixing device,
For example, it can be easily adjusted using a roll, kneader, Raikai machine, Henschel mixer (manufactured by Mitsui Miike Seisakusho), etc.

Next, the epoxy resin composition of the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Experimental Example 1 (Production of Modified Reactants A-H) OH group-containing fluororesin (Lumiflon manufactured by Asahi Glass), silane coupling agent, and solvent were adjusted to have the compositions shown in A-H in Table 1, and Flupen and stirred thoroughly to obtain a uniform composition.

Next, the Kolben was heated to 50°C and reacted for 5 hours to obtain a modified reaction product.

Experimental Example 2 (Production of mixture of modified reactant and inorganic filler) Modified reactants A-H obtained in Experimental Example 1 and inorganic filler were mixed in a Henschel mixer (
(manufactured by Mitsui Miike Seisakusho) to obtain a mixture.

Experimental Example 3 (Produced with filler i-) Modification reaction product B or Hl or γ-glycidoxypropyl trimethoxysilane obtained in Experimental example 1 and an inorganic filler were added so as to have the composition shown in Table 2. Table 1 Examples 1 to 9 and Comparative Examples 1 to 3 As shown in Table 3, polyfunctional epoxy compounds, phenol novolac resins, mixtures of inorganic fillers and modification reactants, curing accelerators, carbon black, carna Ubawax, antimony trioxide, and γ-glydoxybrobyltrimethoxysilane were prepared, kneaded for 7 minutes between heated rolls at 70 to 90°C, and then molded into tablets by a conventional method.

The next obtained tablet was heated to 180℃ and 5oka/a.
1, transfer molded for 1 minute, and then molded at 175℃ for 8 minutes.
After post-curing for several hours, monitor chips for evaluating moisture resistance reliability and test pieces for various evaluations were produced.

The humidity test is PCT (Pressure Cooker)
Te5t) The failure occurrence time was measured under conditions of 121° C. and 2 atm.

In addition, before conducting the moisture resistance test, a monitor chip for evaluating moisture resistance reliability was immersed in a 260°C solder bath for 30 seconds, and then immersed in liquid nitrogen for 30 seconds to give a heat shock.A moisture resistance test was also conducted at the same time. . The results are shown in Table 4.

In addition, the physical properties of the obtained tablets include flexural modulus,
The glass transition temperature, coefficient of linear expansion, volume resistivity, and fluidity were investigated using various evaluation specimens.

As is clear from Table 4, the semiconductor encapsulation epoxy resin composition of the present invention can reduce stress without significantly changing basic properties such as glass transition temperature and coefficient of linear expansion, and fluidity of the composition. It has excellent crack resistance, and as is clear from Table 4, it also has excellent moisture resistance and reliability after heat shock.

[Effects of the Invention] As described above, the epoxy resin composition for semiconductor encapsulation of the present invention has excellent heat shock resistance, heat resistance, and moisture resistance,
Moreover, since the fluidity does not change significantly, it can be advantageously used for encapsulating semiconductors such as ICs and LSIs.

Claims (4)

[Claims] (1) OH group-containing fluororesin and general formula (I): ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, Y is a monovalent organic group containing a phenyl group, an epoxy group, or an amino group, R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, R_1 is a phenyl group, methyl group, or ethyl group, and n is 2 or 3). An epoxy resin composition for semiconductor encapsulation, characterized in that the mixture is mixed with an inorganic filler, and then blended with a polyfunctional epoxy resin and/or a phenol novolac resin, and a curing accelerator. (2) The OH value of the OH group-containing fluororesin is 10 to 16
The epoxy resin composition for semiconductor encapsulation according to claim (1), which has a content of 0 mgKOH/g. (3) Amount A (parts by weight) of the OH group-containing fluororesin
and the amount B (parts by weight) of the silane coupling agent is A/B = 0.2 to 4.0, and the amount of the silane coupling agent is 300 parts by weight of the inorganic filler. The epoxy resin composition for semiconductor encapsulation according to claim (1), wherein the amount is 0.5 to 3.0 parts by weight. (4) The ratio of the amount C (parts by weight) of the modification reaction product of the OH group-containing fluororesin and the silane coupling agent to the amount D (parts by weight) of the inorganic filler is C/D= 0.00
2 to 0.04, the epoxy resin composition for semiconductor encapsulation according to claim (1).