JPH02240132A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in reliability of humidity resistance without detriment to its good moldability by mixing a polyepoxy resin with a phenolic curing agent and a specified cure accelerator. CONSTITUTION:100 pts.wt. mixture of a polyepoxy resin (A) of a free Na ion content and a tree Cl ion content each of which is 5ppm or below, a hydrolyzable halogen content <=500ppm, an epoxy equivalent of 160-250 and a softening point of 50-110 deg.C with a phenolic curing agent (B) (e.g. novolac resin) of an uncondensed phenolic compound content <=1wt.% and a softening point of 60-110 deg.C in a ratio of the phenolic hydroxyl groups to the epoxy groups of 0.5-1.5 is mixed with 0.1-10 pts.wt. cure accelerator (C) comprising a tetraalkylphosphonium 0,0-dialkyl phosphorodithioate of the formula (wherein R1-6 are each a 1-8C acyclic, alicyclic or aromatic hydrocarbon group) and optionally 0.1-10wt.% flexibilizer (D) (e.g. silicone resin powder).

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applicable to the encapsulation of electronic components, especially semiconductors, ICs, and LSIs.
The present invention relates to an epoxy resin composition for semiconductor printing, which is suitable for printing, etc.

(Prior art) In recent years, transfer molding using an epoxy resin composition has become the most effective method for attaching electronic parts, especially semiconductors, ICs, LSIs, etc., as it is inexpensive, has good productivity, and is relatively well-balanced and reliable. Widely used. However, the disadvantage of this molded body is that it is significantly inferior in moisture resistance and reliability compared to hermetic stitches made of non-water permeable materials such as metal cases and ceramics. After the semiconductor device is encapsulated with an epoxy resin composition, the molded product gradually absorbs moisture in the environment in which it is normally used or in an environment where the temperature and humidity are accelerated. The aluminum wiring corroded, leakage current increased, and eventually the wire broke.

Furthermore, in recent years, as electronic components have become smaller and thinner, the mounting method for Kameko components has been shifting from the conventional bottle insertion method to the surface mounting method. In this case, the molded body is immersed in a solder bath and treated at high temperatures during mounting, but the heat treatment at this time causes cracks to form and a decrease in adhesive strength, further reducing moisture resistance reliability. is also occurring.

The above-mentioned disadvantages of prickling with epoxy resin compositions are
(a) The resin is inherently water permeable, fbl
This is due to the fact that the adhesion between the resin and the U-frame, semiconductor elements, etc. is not sufficient, (cam fat contains various impurities, and (d) epoxy toilet fat is brittle. There is.

(al is an essential drawback of resin, mainly rounding (b), (C
) and (d), various improvements have been made. fb
For J, epoxy resin, curing agent, coupling agent,
and internal mold release agents, etc. (C) has been improved by adding epoxy resins, curing agents, fillers, etc., and (D) has been improved by adding flexibility imparting agents to each building.

As a result of these improvements, moisture resistance reliability has steadily improved in recent years, but it is still far from being sufficient due to significant improvements in the degree of integration of semiconductors, miniaturization of wiring, etc.

(Problems to be Solved by the Invention) The present inventors have made earnest efforts to solve these problems, and have found that, in particular, curing accelerators significantly affect moisture resistance reliability. Kaoru observed that when a properties imparting agent was used in combination, the moisture resistance to 4N was improved, and the moldability was also good, and the present invention was completed.

That is, the present invention is applicable to electronic components, particularly semiconductors, ICs, and LSIs.
etc? In the case of resin-sealing fc, while maintaining good moldability, the moisture resistance and reliability, which conventionally could not be said to be sufficient, is significantly improved.

(Means for Solving the Problems) The present invention particularly uses tetraalkylphosphonium 0,O-dialkylphosphonodithioate as a curing accelerator, and more preferably <<> adds a specific flexibility imparting agent. The present invention provides an epoxy resin composition for use with semiconductors, which has excellent moisture resistance, reliability, heat resistance, and good moldability when molding electronic parts and the like.

That is, the present invention comprises (11 (A) polyfunctional epoxy resin (Bl phenol type curing agent fc) tetraalkylphosphonium o.o-dialkylphosphorodithioate shown in the following general formula as a curing accelerator (Next dashi R1 to R6) 01-CB chain, alicyclic, l
(m is an aromatic hydrocarbon group) An epoxy resin composition for sealing semiconductors, which contains the following three components as main components; and an epoxy resin composition for sealing semiconductors, which contains the resin composition and a flexibility imparting agent as main ingredients. It is.

Next, the present invention will be explained in detail.

Any polyfunctional epoxy adhesive used in the present invention can be used as long as it has two or more epoxy groups in one molecule. For example, bisphenol A type epoxy resin, novolak type epoxy 4i {1l1i synthesized from various phenols, na7talene-1.6-1' glycidyl ether, 4. 4'-bis(2,3-epoxybroboxy)-3.6'. 5.5'-Tetramethylbiphenyl, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, chain aliphatic epoxy resin, fatty epoxy resin, heterocyclic epoxy resin, hexafunctional epoxy resin, tetrafunctional epoxy ．． Examples include epoxy resins or epoxy resins in which halogens such as 1 or bromine are introduced, and one of these, if 2 or more, is used. Among these, cresol novolak type, phenol novolac type epoxy resin, and 4.4'
-bis(2.3-epoxyproboxy)-3.3'. 5
．． 5'-tetrametherbiphenyl is preferred.

The fewer ionic impurities and components that easily decompose into ions in these epoxy resins, the better. Specifically, free sodium ions and chlorine ions are each 5
1) 1) m or less and town water decomposable halogens are 500
It is preferably less than ppm. Epoxy equivalent weight is 160 to 25
0, particularly preferably 160 to 210. The resin used has a softening point of 50 to 110°C.

As the (S) phenol type curing agent used in the present invention, one having at least two or more hydroxyl groups in one molecule is used. For example, phenol, resorcinol, cresol, xylenol, flobylphenol, amylphenol, buterphenol, octerphenol,
Phenylphenol, allylphenol, gesphenol A, etc. are used alone, and the case m is a novolak resin synthesized by combining them, polyimpropenylphenol, polyvinylphenols, and 9 phenol type curing by introducing a halogen group χ into these. Among these, 1
Two or more types of kashimoshi are used. Among these, there is 1 uncondensed phenolic compound! Noporac resins with a weight ratio of less than 0.5%, preferably less than 0.5% by weight, are preferred. As for the softening point, those having a softening point of 60 to 1108C are used.

The blending amount of the curing agent is such that the ratio of the phenolic aqueous group of the curing agent to the epoxy group of the epoxy resin is in the range of 0.5 to 1.5, particularly preferably in the range of 0.7 to 1.2. It is better. Outside the above range, the moisture resistance reliability χ is unfavorable.

Next, the curing accelerator used in the present invention must be tetraalkylphosphonium 0,o-dialkylphosphoroditeoate (the following formula).

(However, R1~Fl, C'l-c, chain, alicyclic, primary aromatic hydrocarbon group) Specifically, tetra n-butylphosphonium 0,0
-diethylphosphorodithioate, tetra-n-octylphosphonium o,0-jethylphosphorodithioate, tetraphenylphosphonium-0.0-jethylphosphorodithioate, and the like. The amount of these additives is 0.1!, based on 100 parts by weight of the epoxy resin and curing agent. Part 1 Kara 1 0 Heavy is Kakou I
L<, particularly preferably from 0.5i parts to 5 parts by weight.

Next, examples of the flexibility imparting agent used in the present invention include the following. Silicone polymers, polysulfide imes, butadiene-modified imes, hydrogenated t-sterene-butadiene block copolymers, hydrogenated t-sterene-isoprene block copolymers, hydrogenated acrylonitriloptadiene copolymers, carboxyl groups, trialkoxylyl Epoxy resins such as those with functional groups that can react with phenolic curing agents, thermal Q[glue-like substances such as elastomers, oily substances such as silicone oil, various thermoplastic resins, and silicone resins] Resin-like substances such as powder, or epoxy
Examples include phenol resins partially or entirely modified with Sχ amine silicone, epoxy silicone, alkoxy silicone, etc.

Particularly preferred among these are +a) hydrogenated sterene-butadiene block copolymers, hydrogenated sterene-isoprene block copolymers, hydrogenated 9-acrylonitrile-butadiene copolymers, which contain carboxyl groups, trialkoxy Epoxy resins such as silyl groups have functional groups that can react with phenolic curing agents; (b) reactive silicones that have two or more functional groups that can react with each other, such as amino silicone and epoxy silicone; Examples include those modified in advance with an epoxy resin casing or a phenolic curing agent, or silicone resin powder. The above (a) and 1fc are (b) χ
When using 7'C, it is possible to obtain not only good moisture resistance reliability but also good moldability without bleeding. Furthermore, since it is a flexibility-imparting agent with good heat resistance, even if the molded product is left at high temperatures for a long period of time, it can remain stable and maintain its performance.

The addition level of the above-mentioned flexibility imparting agent is 0.1 to 0.1 to
10 weights or more, preferably 0.3 to 5 weights! It is k width.

If it is less than 0.1 weight ratio, there will be no effect on moisture resistance reliability, and if it is more than 10 weight ratio, it will cause poor moldability such as decreased flowability and frequent formation of pinholes.

Next, it is preferable to add an inorganic filler to the epoxy resin composition for suppressing semiconductors of the present invention in order to improve the thermal conductivity or reduce the thermal expansion coefficient χ. Examples of the inorganic filler used in the present invention include powders such as crystalline silica, bath-fused silica, talc, alumina, calcium sulfate, calcium carbonate, barium carbonate, and silicon nitride, as well as glass, silicon nitride, silicon carbide fibers, and whiskers. Two or more rods are used for each type of primary.

Among these, silica, especially fused silica, is preferred because it has high purity and a low coefficient of thermal expansion.

In addition to the usual crushed products, spherical ones are also suitably used.

The amount of the filler to be blended is 68% by weight or more, preferably 70% by weight or more based on the entire composition, and the larger the amount is, the better, as long as moldability etc. are not impaired. In particular, when the spherical filler is used in some cases, it can be blended in amounts of 80% or more by weight.

The epoxy resin composition for controlling semiconductors of the present invention may contain carnapa wax, montan wax, higher fatty acids and their calcium salts, fluorocarbon compounds, mold release agents such as solid primary oil silicone, and halodane epoxy resins. Flame retardants such as resins and antemon oxide, colorants such as carbon plaque, etc.? It is also preferable to add maleimide and other imide compounds to this composition because they improve heat resistance.

The composite of the present invention can be produced by mixing the above-mentioned materials in a blender case or mixer, melt-kneading them with a heating roll or seconder, and then cooling and pulverizing them.

Next, examples of the present invention will be shown.

(Examples and Comparative Examples) Examples 1 to 7 and Comparative Examples 1 to 7! All parts below 1 indicate parts by weight.

45 parts of phenol novolac tree (curing agent), 500 parts of fused silica powder (average particle size 15 μl), 3 parts of Hoechst wax, 1.5 fl of carbon black, 10 g of antemon trioxide, r-glycidoxypropyltrimethoxysilane The composition of 6 parts was constant, and the curing accelerator shown in Table 1,
The flexibility imparting agent was weighed, mixed with a mixer, kneaded with heated rolls, cooled and pulverized to obtain an epoxy resin composition.

These compositions were tested for moisture resistance reliability, and a silicon element χ16 for evaluation having aluminum arrangement II facing each other was tested.
Each composition was transfer molded into a bottle DIP. After the after-cure, the molded product was immersed in a 260°C solder bath for 10 seconds and then accelerated to determine its moisture resistance.
The Pretschaktzker test (hereinafter referred to as PC'l') under saturated pressurized steam at 25°C and a bias of 2C]V! The sample was subjected to the Bias Pretzker Test (hereinafter referred to as BPCT). Twenty devices were used in each test, and the number of devices that developed open defects due to corrosion of the aluminum wiring was investigated over time. The results are shown in Figure 2.

(Effects of the Invention) As is clear from the above examples, the epoxy resin composition for inhibiting semiconductors of the present invention has significantly good PCT and BPCT, and is suitable for electronic components, particularly semiconductors, ICs, LSIs, etc. It has characteristics.

Claims (4)

[Claims] (1) (A) Polyfunctional epoxy resin (B) Phenol type curing agent (C) As a curing accelerator, tetraalkylphosphonium O, O-dialkylphosphorodithioate shown in the following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, R_1 to R_6 are chain, alicyclic, or aromatic hydrocarbon groups of C_1 to C_8) An epoxy resin composition for semiconductor encapsulation whose main components are the following three components. (2) The epoxy resin composition for semiconductor encapsulation according to claim (1), which contains claim (1) and a flexibility imparting agent. (3) The epoxy resin composition for semiconductor encapsulation according to claim (2), wherein the flexibility imparting agent is a hydrogenated styrenic block copolymer or a hydrogenated acrylonitrile-butadiene copolymer. (4) The epoxy resin composition for semiconductor encapsulation according to claim (2), wherein the flexibility imparting agent is a silicone resin powder.