JPH04292614A - Resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent soldering stress resistance, moisture resistance, etc., and useful for the sealing of electronic parts such as transistor and integrated circuit by using a specific epoxy resin, a phenolic resin hardener, an inorganic filler and a cure accelerator as essential components. CONSTITUTION:The objective composition can be produced by compounding (A) an epoxy resin containing 50-100wt.% (based on total epoxy resin) of 3,3',5,5'- tetramethyl-4,4'-dihydroxybiphenyl glycidyl ether of formula I with (B) a phenolic resin hardener containing 50-100wt.% (based on total phenolic resin hardener) of a phenolic resin hardener of formula II (n is 0-5; R is H, halogen or 1-4C alkyl), (C) an inorganic filler (preferably fused silica powder), (D) a cure accelerator (e.g. diazabicyclo-undecene) and, as necessary, (E) a silane-coupling agent, a flame-retardant, a coloring agent (e.g. iron oxide red), etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for encapsulating semiconductors having excellent solder stress resistance and moisture resistance.

0002

[Prior Art] Conventionally, electronic components such as diodes, transistors, and integrated circuits have been encapsulated with thermosetting resins.In particular, for integrated circuits, ortho-cresol novolac epoxy resins with excellent heat resistance and moisture resistance are used. Epoxy resin cured with phenolic resin is used. However, the mounting method for semiconductor packages has changed from conventional through-hole mounting to surface mounting, and the types of semiconductor packages have changed from DIP to SOP to SO.
J, it is changing to PLCC. And recently, the thickness of the package is about 1 m, which is much thinner than the conventional one.
Packages called m-thick TSOP and TQFP are also appearing.

That is, by enclosing a large chip in a small and thin package, problems such as the occurrence of cracks due to stress and a decrease in moisture resistance due to these cracks have been brought into focus. In particular, problems have arisen in that moisture resistance deteriorates due to cracking of the package, peeling between the resin and the chip, etc. due to sudden exposure to high temperatures of 200° C. or higher during the soldering process. Therefore, there is a need for a sealing resin that can meet the two requirements of soldering heat resistance and moisture resistance.

To solve these problems, in order to alleviate the thermal shock during soldering, addition of thermoplastic oligomers (Japanese Unexamined Patent Publication No. 62-115849) and various silicone compounds (Unexamined Japanese Patent Publication No. 62-115849) have been proposed. -11585 Publication, 62-
116654, 62-128162) and silicone modification (Japanese Unexamined Patent Publication No. 62-136860), but all of these techniques resulted in cracks in the package during soldering, making it difficult to maintain reliability. However, it has not been possible to obtain an epoxy resin composition for semiconductor encapsulation.

On the other hand, in order to obtain a heat-resistant epoxy resin composition with excellent solder stress resistance, a polyfunctional epoxy resin is used as the resin system (Japanese Unexamined Patent Publication No. 168620/1983).
The use of polyfunctional epoxy resins increases crosslinking density and improves heat resistance, but especially at 200°C.
When exposed to high temperatures such as ~300°C, the solder stress resistance was insufficient.

[0006]

OBJECTS OF THE INVENTION The present invention provides a resin composition for semiconductor encapsulation which has excellent solder stress resistance and moisture resistance.

[0007]

[Means for Solving the Problems] In order to solve these problems, the present inventors conducted extensive research and discovered a resin composition having the following composition. Formula [I] as epoxy resin
3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl glycidyl ether represented by the chemical structural formula

[0008]

Formula [II] as an epoxy resin containing 50 to 100% by weight of [Chemical formula 3] and a phenol resin curing agent based on the total amount of epoxy resin
Dicyclopentadiene-modified phenolic resin curing agent with the structure shown in

[0009]

[Chemical formula 4] (n is an integer and n=0 to 5, R in the formula is an atom or group selected from a hydrogen atom, a halogen atom, and an alkyl group having 1 to 4 carbon atoms) is cured with a total phenolic resin A resin composition containing as essential components a phenolic resin curing agent, an inorganic filler, and a curing accelerator containing 50 to 100% by weight based on the amount of the agent,
It has extremely superior solder stress resistance and moisture resistance compared to conventional epoxy resin compositions.

0010

[Operation] The biphenyl type epoxy compound having the structure represented by the formula [I] used in the present invention has a molding temperature (175
Because it has a very low viscosity compared to traditional epoxy resins, only a few centipoise at ℃), it is possible to significantly increase the filler content, which improves the impact strength of the resin composition and improves solder heat resistance. It has the characteristic of being excellent in quality. The biphenyl-type epoxy compound represented by formula [I] may be used alone or mixed with other epoxy resins, but it is necessary that the biphenyl-type epoxy compound accounts for 50% by weight or more of the total amount of epoxy resin. It is. 50%
If it is less than 20%, the composition will have poor fluidity. Epoxy resins used in combination include orthocresol novolac epoxy resins, trifunctional epoxy resins, and the like, and these may be used alone or in combination of two or more.

The dicyclopentadiene-modified phenolic resin curing agent having the structure represented by formula [II] is characterized by having a flexible dicyclopentadiene structure in the molecule, and by using this, It is possible to obtain an epoxy resin composition that is highly flexible and has good solder stress resistance.

By adjusting the amount of the dicyclopentadiene-modified phenolic resin curing agent used, the solder stress resistance can be maximized. In order to obtain the effect of solder stress resistance, it is desirable to use the dicyclopentadiene-modified phenol resin curing agent in an amount of 50% by weight or more, preferably 70% by weight or more based on the total curing agent. If it is less than 50% by weight, flexibility will not increase and solder stress resistance will be insufficient.

[0013] The curing agent used in combination with the dicyclopentadiene-modified phenol resin curing agent having the structure represented by formula [II] includes any curing agent that reacts with epoxy resins, such as phenol noporasoc resin, cresol noporasoc resin, etc. A resin, tris(hydroxyalkylphenyl)methane type phenol resin, paraxylene modified phenol resin, etc. can be used.

The blending ratio of the epoxy resin and the phenolic resin curing agent must be adjusted so that the number of epoxy groups in the epoxy resin is within the range of 0.5 to 2 to 1 hydroxyl group in the curing agent. If it is less than 0.5 or more than 2, the moisture resistance, molding workability, and electrical properties of the cured product will be poor. Preferably, the curing agent has 1 hydroxyl group and the epoxy resin has 1.1 to 1.3 epoxy groups. If it is less than 1.1 or more than 1.3, water absorption increases, thermal shock during solder immersion increases, and solder stress resistance tends to deteriorate.

As the inorganic filler used in the present invention, fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, secondary agglomerated silica powder, or pulverized porous silica powder can be used. Examples include powder, alumina, etc., and fused silica powder is particularly preferred.

The curing accelerator used in the present invention may be one that promotes the reaction between the epoxy group and the phenolic hydroxyl group, and a wide variety of those commonly used in sealing materials can be used. For example, diazabicundecene (DBU), triphenylphosphine (TPP), dimethylbenzolamine (BDMA), 2methylimidazole (2MZ), and the like are used alone or in combination of two or more.

The sealing resin composition of the present invention contains an epoxy resin, a phenol resin curing agent, an inorganic filler, and a curing accelerator as essential components, but in addition to these, a silane coupling agent and a brominated epoxy resin are optionally added. Various additives such as resins, flame retardants such as antimony trioxide and hexabromobenzene, colorants such as carbon black and red iron, mold release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber. There is no problem in appropriately blending.

In order to produce the encapsulating resin composition of the present invention as a molding material, the epoxy resin, curing agent, curing accelerator, filler, and other additives are thoroughly and uniformly mixed using a mixer or the like. After that, the mixture is further melt-kneaded using a heated roll or a kneader, cooled, and then crushed to obtain a molding material. These molding materials can be applied to sealing, covering, insulating, etc. electronic or electrical components.

[0019]

[Examples] The present invention will be illustrated below with examples. The blending ratio is expressed in parts by weight.

Examples 1 to 4, Comparative Examples 1 and 2 The compositions having the proportions shown in Table 1 were thoroughly mixed at room temperature.
The mixture was further kneaded with a twin-screw roll at 95 to 100°C, cooled, and then ground to obtain a molding material, which was then made into tablets to obtain an epoxy resin composition for semiconductor encapsulation.

*1 Dicyclopentadiene-modified phenol resin represented by formula [III]

[0022]

[Chemical formula 5] (Mixture where the ratio of compounds n=1, 3, 4 is 2:6:2)

This material was molded using a transfer molding machine (molding conditions: mold temperature: 175°C, curing time: 2 minutes), and the resulting molded product was post-cured at 175°C for 8 hours and evaluated. The results are shown in Table 1.

Evaluation method *2 Spiral flow: Using a spiral flow measurement mold conforming to EMMI-I-66, 20g of the sample was
Molding temperature: 175°C, molding pressure: 7.0 MPa, molding time: 2
The length of the molded product when molded in minutes. *3 Soldering heat resistance test: Molded product (chip size 36m)
m2, package thickness 2.05mm) 85 for 20 pieces
℃, 240℃ after 72 hours of treatment under steam at 85% RH
The number of molded products that cracked after being immersed in a solder bath for 10 seconds is shown. *4 Solder moisture resistance test: 85% of sealed test element
℃, treated for 72 hours in an environment of 85% RH, and then treated for 2 hours.
After being immersed in a solder bath at 50° C. for 10 seconds, a pressure cooker test (125° C., 100% RH) was conducted to measure open defects in the circuit.

[0025]

[Table 1]

[0026]

[Effects of the Invention] The resin composition for semiconductor encapsulation according to the present invention has extremely excellent soldering heat resistance and moisture resistance, and is extremely reliable as a resin composition for surface mount encapsulation.

Claims (1)

[Claims] Claim 1: (A) 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl glycidyl ether [Chemical formula 1] represented by the chemical structural formula of formula [I] in a total amount of epoxy resin Epoxy resin (B) containing 50 to 100% by weight of a phenolic resin curing agent represented by formula [II] [Chemical formula 2] (n is an integer and n = 0 to 5, R in the formula is a hydrogen atom, A phenolic resin curing agent (C) containing 50 to 100% by weight of a halogen atom, an atom or group selected from alkyl groups having 1 to 4 carbon atoms, based on the total amount of phenolic resin curing agent.
A resin composition for semiconductor encapsulation, characterized in that it contains an inorganic filler (D) and a curing accelerator as an essential component.