JPH0337566B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy resin composition suitable for encapsulating semiconductors having metal electrodes such as aluminum. BACKGROUND ART In recent years, semiconductor devices such as transistor devices and integrated circuit devices have been widely encapsulated using thermosetting resin compositions such as epoxy resins. This is because the sealing operation is simpler and more economical than the conventional hermetic method using metal or ceramic materials. However, on the other hand, the resin sealing method has the disadvantage of being inferior in reliability under high temperature and high humidity compared to the hermetic method. That is, the reason for the poor reliability at high temperature and high humidity is considered to be as follows. Since the epoxy resin molded body itself has water permeability, moisture that has entered the molded body permeates to the surface of the resin-sealed semiconductor element, corroding and degrading metal electrodes such as aluminum. In addition, at this time, the water dissolves corrosive ionic impurities such as Na ⁺ and Cl ^- contained in the epoxy resin molded body and carries them to the surface of the semiconductor element, promoting corrosion of the metal. These ionic impurities are generated or mixed in during the production of epoxy resins, etc., but it is difficult to completely eliminate them due to the process. In addition to these corrosive ionic impurities, epoxy resins contain about 10 to 1000 times more hydrolyzable chlorine than the ionic impurity chlorine. These are not easily desorbed by moisture intrusion alone, but are ionized and eluted by the action of heat or a catalyst, which causes corrosion of aluminum electrodes and the like. As described above, since the epoxy resin sealing method has problems with moisture resistance and corrosion resistance, various attempts have been made to date to improve the reliability of resin sealing. For example, selecting materials for resin compositions that have fewer impurities (Japanese Patent Laid-Open No. 56-26926), or considering curing accelerators that improve the moisture resistance and corrosion resistance of molded products (Japanese Patent Laid-Open No. 56-158461). (No. 56-72045), adding a corrosion inhibitor to the resin composition (Japanese Patent Application Laid-open No. 56-72045,
JP-A-56-72046, JP-A-56-104926, JP-A-56-160056, JP-A-56-16005), but no significant effects have been found. In response, the present inventors have conducted various studies in order to improve the moisture resistance reliability of resin encapsulation. Moisture-resistance reliability is also affected by organic substances such as phenols, amines, and carboxylic acids (hereinafter referred to as free organic substances) that are contained as impurities in water or are decomposed and liberated during heating or kneading. Adsorption resins based on polymers of acrylic acid esters or adsorption resins based on polymers of styrene and divinylbenzene (hereinafter referred to as organic substances) have a major adverse effect and remove these free organic substances from the system. We have discovered that when a semiconductor having an aluminum electrode or the like is encapsulated using an epoxy resin composition containing a substance adsorbing resin, moisture resistance reliability is dramatically improved compared to conventional products. In other words, by adding organic material adsorption resin, even in accelerated moisture resistance tests in high-temperature, high-pressure steam, the disconnection rate due to aluminum electrode corrosion and the failure rate due to leakage current between aluminum electrodes are significantly reduced and suppressed compared to conventional products. The desired performance can be maintained and exhibited over a long period of time. This effect is caused by free organic substances from organic materials being carried to the surface of semiconductor elements by infiltrating moisture, which promotes metal corrosion, increases conductivity between electrodes, and increases leakage current. This is thought to be because the organic substance adsorption resin removes the organic substance and prevents it from occurring. Based on the above findings, the present invention provides epoxy resins,
Epoxy with a composition whose main components are a curing agent and an inorganic filler and an organic substance adsorption resin (an adsorption resin whose matrix is a polymer of acrylic ester or an adsorption resin whose matrix is a polymer of styrene and divinylbenzene). By using the resin composition, the present invention aims to provide an epoxy resin composition for encapsulating semiconductor devices that has high moisture resistance and corrosion resistance against metal electrodes such as aluminum. That is, the present invention includes 100 parts by weight of a composition containing an epoxy resin, a curing agent, and an inorganic filler as main components;
Organic substance adsorption resin (adsorption resin based on a polymer of allylic acid ester and/or adsorption resin based on a polymer of styrene and divinylbenzene)
An epoxy resin composition for encapsulating a semiconductor device, characterized in that the composition contains 0.5 to 30 parts by weight. The epoxy resin used in the present invention is not particularly limited in molecular structure, molecular weight, etc., as long as it has at least two or more epoxy bonds in its molecule. For example, bisphenol A type epoxy resin,
Examples include phenol novolac type epoxy resins and cresol novolac type epoxy resins, but those containing less impurities and hydrolyzable chlorine are desirable. Examples of the epoxy resin curing agent include phenolic curing agents such as phenol novolac resin and cresol novolac resin, amine curing agents, and acid anhydride curing agents.
There are no particular restrictions on the amount of these used, but
It is necessary to add stoichiometric amounts of epoxy groups and curing agent. Furthermore, examples of inorganic fillers include powders such as crystalline silica, fused silica, calcium silicate, alumina, calcium carbonate, talc, and barium sulfate, or glass fibers, but crystalline silica Or fused silica is used. The blending ratio of these inorganic fillers to the total varies depending on the selected resin content, but
Generally, the amount may be about 150 to 450 parts by weight per 100 parts by weight of the resin content. If it is less than 150 parts by weight, the coefficient of thermal expansion and molding shrinkage will be large, and the thermal conductivity will be low.
If the amount exceeds 1 part by weight, there are drawbacks such as decreased fluidity and increased mold wear. The organic substance adsorption resin contained in the epoxy resin composition of the present invention may be an adsorption resin based on a polymer of acrylic acid ester or an adsorption resin based on a polymer of styrene and divinylbenzene, and may be used singly, as a mixture of the same type, or as a mixture thereof. It may be a mixture of different types. An example of the structure of organic substance adsorption resin is formula 1,
As shown in Formulas 2 and 3, there are no particular limitations as long as R ₁ is an alkyl group and R ₂ is an alkylene group. These organic substance adsorption resins are specifically Amberlite XAD, series and
It is commercially available as the XE series, the Duolite adsorption resin series manufactured by Sumitomo Chemical Co., Ltd., and the Diaion HP series manufactured by Mitsubishi Chemical Industries, Ltd. Since this organic substance adsorption resin has a larger adsorption capacity as the adsorption area becomes larger, it is preferable to use as porous spherical fine powder as possible, which is effective in adsorbing both polar and non-polar free organic substances. They are spherical in shape and range from those that adsorb non-polar organic substances to those that adsorb polar organic substances. In the present invention,
All of these organic substance adsorption resins are effective;
Furthermore, one type or a mixture of two or more types selected from these may be used. Examples include polymers of styrene and divinylbenzene and polymers of acrylic esters, examples of which structures are shown in formulas 1, 2 and 3. In this formula
There are no particular limitations as long as R ₁ is an alkyl group and R ₂ is an alkylene group. There are no particular restrictions on the overall form of these organic substance adsorption resins, but since the larger the adsorption area, the greater the adsorption capacity, it is preferable that the resin be as porous and as fine as possible. Specific examples of these organic substance adsorption resins include Amberlite XAD series and XE series manufactured by Organo, Dulite adsorption resin series manufactured by Sumitomo Chemical Co., Ltd., and Diaion HP series manufactured by Mitsubishi Chemical Industries, Ltd. .

【formula】

[Formula] The amount of the organic substance adsorption resin of the present invention added to 100 parts by weight of the epoxy resin composition is preferably from 0.5 to 30 parts by weight, more preferably from 1 to 20 parts by weight. If the amount added is less than 0.5 parts by weight,
This is because the adsorption effect of free organic substances does not appear, and if the amount exceeds 30 parts by weight, the fluidity during heating and melting will decrease. In addition, the longer the time between adding these organic substance adsorption resins to the epoxy resin composition to produce the molding material and sealing the actual device, the more effectively the organic substance adsorption resins can remove free organic substances. , so it is preferable to leave it for a long time, and it is more effective to leave it for 10 days or more. The temperature at which the product is left to stand is preferably as low as possible, preferably 10°C or lower, since a high temperature will cause a curing reaction. Furthermore, other optional components that may be added as necessary include curing accelerators such as phosphines such as triphenylphosphine or imidazoles, flame retardants such as brominated epoxy resins and antimony trioxide, and pigments such as carbon black. ,
Examples include interface reinforcing agents such as silane coupling agents, mold release agents such as Montana wax and carnauba wax, and flexibility imparting agents such as silicone compounds. The production of the epoxy resin composition according to the present invention can be easily carried out by sufficiently mixing raw materials having a predetermined composition ratio using a mixer or the like, and then further applying a melt-mixing treatment using a heated roll, kneader, or the like. The present invention will be explained in detail below with reference to Examples. Examples 1-7 Cresol novolak resin with epoxy equivalent weight 230
To 85 parts by weight, 15 parts by weight of brominated epoxy resin, 50 parts by weight of phenol novolac resin, 5 parts by weight of 2-undecylimidazole, 2.5 parts by weight of carnauba wax, 1 part by weight of carbon black, silane coupling agent ( γ-glycidoxypropyltrimethoxysilane) 3 parts by weight, antimony trioxide
To a composition consisting of 10 parts by weight of crystalline silica and 350 parts by weight of crystalline silica, organic substance adsorption resins were added in the proportions shown in Table 1, mixed with a mixer, further kneaded with heated rolls, and then cooled. and crush it, 7
Various types of molding materials were manufactured. Using each of the resin compositions prepared in this way, an element having opposing aluminum wire electrodes was sealed by transfer molding. Then, for this sealed sample, a bias current of 20 V DC was applied between the electrodes at a temperature of 125°C and under a steam pressure of 2.5 atm. Moisture resistance and corrosion resistance were evaluated by comparing the rate at which the leakage current value became 10 nA or more for each sample. At this time, the open defect rate is the number of defective items out of 50 evaluated items, and the leak defect rate is 25.
Each was calculated from the number of defective pieces among the pieces. In addition, when no voltage is applied between the electrodes (non-bias), 125
Similarly, changes over time in the open defect rate and leak defect rate in water vapor at 2.5 atm and ℃ were also investigated. The results are shown in Table 1. Comparative Examples 1 to 6 Next, as comparative examples, the above-mentioned epoxy resin composition was prepared without adding an adsorbent for these free organic substances, and instead of these, ammonium phosphate, orthoboric acid, and alizarin were added as corrosion inhibitors. , orthonaphthoquinone, and aluminum trisacetylacetonate in the proportions shown in Table 2. Samples were prepared in the same manner as in the examples and evaluated. The results are shown in Table 2.

【table】

【table】

【table】

[Table] The adsorption resins (organic substance adsorption resins) are as follows. 1 Adsorption resin (1): Polymer system of styrene and divinylbenzene, manufactured by Mitsubishi Chemical Industries, Ltd., trade name: Diaion HP20 2 Adsorption resin (2): Polymer system of acrylic acid ester, manufactured by Mitsubishi Chemical Industries, Ltd. Product name Diamond Aeon
HP2MG 3 Adsorption resin (3): Polymer system of acrylic acid ester, manufactured by Organo Co., Ltd., trade name: Amberlight
XAD-7 4 Adsorption resin (4): Acrylic acid ester polymer system, manufactured by Organo Co., Ltd., trade name Amberlight
XAD-8 5 Adsorption resin (5): Polymer system of styrene and divinylbenzene, manufactured by Sumitomo Chemical Co., Ltd., trade name Duolite S862

Claims (1)

[Claims] 1 100 parts by weight of a composition whose main components are an epoxy resin, a curing agent, and an inorganic filler, and an adsorption resin whose matrix is a polymer of acrylic ester and/or an adsorption resin whose matrix is a polymer of styrene and divinylbenzene. An epoxy resin composition for encapsulating a semiconductor device, comprising 0.5 to 30 parts by weight.