JPH0556018B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy resin composition for semiconductor encapsulation using a resol type phenolic resin as a curing agent. As a semiconductor sealing material, there are known compounds in which an epoxy resin and a novolak type phenolic resin are used as a curing agent without a catalyst or with tertiary amines, imidazoles, quaternary ammonium salts, or organic metal salts as a curing accelerator. ing. Resin compositions with high reliability, particularly moisture resistance, are required for semiconductor encapsulation materials, and up to now, novolak type phenolic resins have been generally used as curing agents for epoxy resins due to their moisture resistance. The reason for this is that compared to acid anhydride curing, deterioration due to moisture absorption is small and production workability and moldability are excellent. However, in recent years, there is a demand for more reliable resin compositions, and conventional novolac type phenolic resins cannot be used as they are, but are currently used after adding processes such as washing. This is to suppress ionic impurities in the resin material as much as possible, and to remove catalyst residues such as hydrochloric acid, sulfuric acid or oxalic acid used during the synthesis of novolak phenolic resin. For this reason, the use of novolak type phenolic resins has become very disadvantageous in terms of cost. The present invention has been made in view of the above points, and provides an epoxy resin composition for semiconductor encapsulation that is characterized by blending a resol type phenolic resin as a curing agent with an epoxy resin, and has excellent moisture resistance and reliability. It is something to do. Because alkali catalysts such as ammonia and slaked lime are used to synthesize resol-type phenolic resins, when the resin composition is manufactured, it is neutral to acidic compared to the acidic resin composition using novolac-type phenolic resin. It becomes weakly alkaline and is advantageous against corrosion of aluminum wiring in semiconductor devices.
Furthermore, since the resol type phenolic resin has a hydroxyl group and a methylol group in its structure, it is a curing agent for epoxy resin, and at the same time, the resin itself cures itself. Therefore, the amount of unreacted substances is extremely reduced compared to when a novolak type phenolic resin is used. For these reasons, moisture resistance and reliability are improved. Further, in the present invention, it is preferable that the resol type phenolic resin contains 5 to 25% by weight of a resin having a molecular weight of 800 or more. If it is less than this, curability and heat resistance will decrease. As the resol-type phenolic resin that can be applied to the present invention, a condensation product obtained by reacting a monovalent phenol without a substituent such as an alkyl group with formaldehyde under an alkaline catalyst is used, and the resulting resol-type phenolic resin is used. The method for adjusting the molecular weight of the resin can be controlled by the molar ratio of the phenols and formaldehyde and the type and amount of the catalyst used. Further, as catalysts that can be used, general alkalis such as ammonia, slaked lime, and caustic potash, metal salts thereof, or two or more thereof can be used in combination. Synthesis conditions cannot be determined unconditionally because they vary depending on the catalyst species, catalyst amount, molar ratio, etc., but the condensation product can be easily determined by liquid chromatography, and the desired resol type phenolic resin can be obtained. It is preferable that the resol type phenolic resin is blended in an amount of 0.6 to 1.3 equivalents to the epoxy resin. The epoxy resin applicable to the present invention refers to all known epoxy resins containing two or more epoxy groups in one molecule, such as bisphenol-based epoxy resins obtained from bisphenol A and epichlorohydrin. Epoxy resin, novolac type epoxy resin obtained by reacting novolac resin with epichlorohydrin, epoxy resin obtained from alicyclic compounds such as cyclohexene, cyclopentadiene, and dicyclopentadiene, epoxy resin obtained from vinyl polymer, glycerin, etc. There are epoxy resins obtained from polyhydric alcohols, and at least one of these is used. In addition to the above-mentioned epoxy resin and resol-type phenolic resin, the epoxy resin composition of the present invention may contain 40 to 70% by volume of the entire composition, if necessary.
Inorganic fillers such as silica glass fiber and alumina are blended. Furthermore, if necessary, catalysts, mold release agents, pigments,
It is also possible to blend a surface treatment agent, a flexibilizing agent, etc. The catalyst is preferably a tertiary amine such as penzyldimethylamine, imidazole, etc., and the surface treatment agent is preferably epoxysilane. The method for producing the epoxy resin composition of the present invention is to mix the epoxy resin and resol type phenolic resin with additives such as the above-mentioned fillers and catalysts as necessary, and then knead and extrude using a kneader, a grinder, or a single or twin screw. Mix using a machine. Heating is performed until the softening point of the resin used is reached, but the temperature is 100°C.
It is desirable not to exceed ℃. The present invention will be explained below according to examples, but the present invention is not limited in any way. Note that parts in each column hereinafter mean parts by weight. Example 1 and Comparative Example 1 Formaldehyde and phenol in a molar ratio of 1.08,
Using a 25% ammonia aqueous solution as a catalyst, stir in a flask to warm up the temperature, then heat to 90°C while refluxing.
After reacting for 120 minutes, the liquid temperature was lowered to 70°C and concentration under reduced pressure was performed for 120 minutes. After that, return to normal pressure and raise to 105℃.
The mixture was concentrated for 15 minutes to obtain a resol type phenolic resin (A). To determine the molecular weight distribution of the obtained resol type phenolic resin (A), liquid chromatography (HLC) manufactured by Toyo Soda Co., Ltd. was used.
We measured the abundance of G3000H and G2000H in combination. For comparison, the molar ratio of formaldehyde and phenol to the above resol type uhenol resin (A)
1.2. The reaction was carried out at 94°C for 110 minutes using caustic soda as a catalyst, and then the liquid temperature was lowered to 65°C and concentrated under reduced pressure for 110 minutes. Thereafter, the pressure was returned to normal, and the mixture was concentrated at 105°C for 20 minutes to obtain a resol type phenolic resin (B). When the molecular weights of the obtained phenolic resins (A) and (B) were examined, resin (A)
contained approximately 7-10% of molecules with a molecular weight of 800 or higher, and resin (B) contained 2-3% of molecular weights of 800 or higher. Each of the obtained resol type phenolic resins (A) and (B)30
100 parts of Epicote 1011 (trade name of bisphenol type epoxy resin made by Ciel), Imidazole C ₁₁ Z
(manufactured by Shikoku Kasei Co., Ltd.) and 80 parts of methanol were added and stirred in a beaker to completely dissolve the resin compositions [] and []. The resin composition [] is a resol type phenol resin (A) (Example 1), []
uses resol type phenolic resin (B) (Comparative Example 1). The properties of these resin compositions [] and [] are shown in Table 1. In Table 1, the gel time is 150% using a hot plate specified in JIS C2104.
Judgment was made based on the time it takes for fluidity to disappear at °C. Hardness and secondary transition point samples were dried at 85°C for 30 minutes and 110°C for 20 minutes, and then pressure molded at 150°C for 30 minutes (pressure 70 kg/
cm ² ) to prepare a cured product. The hardness is determined using Shore D, and the secondary transition point is determined using TMA (Thermal
Mechanical Analgsis) was used. To prepare an extract, the cured product was ground and extracted with distilled water at 121°C and 2 atm. Resin composition [] has higher hardness and second-order transition point than [], and also has good results as an aqueous extraction solution. Comparative Example 2 Formalin and phenol in a molar ratio of 0.79, hydrochloric acid,
90°C at 80°C with stirring in a flask using oxalic acid as a catalyst.
The reaction was carried out under reflux for 60 minutes at 100°C, and then heated and dehydrated under reduced pressure until the temperature of the contents reached 130°C.
I got it. 25 parts of this phenol resin (C) was coated with epoxy resin Epicoat as in Example 1 and Comparative Example 1.
Add 100 parts of 1001, 1 part of imidazole C ₁₁ Z, and 130 parts of methanol to completely dissolve and form a resin composition []
...Comparative Example 2 was created. The properties of this resin composition [] are also listed in Table-1. The resin composition of Comparative Example 2 [] had a shorter gel time than that of Example 1,
Although the hardness and secondary transition point are the same, the pH of the extracted water is acidic and the electrical conductivity is about 2 that of the product of the present invention (Example 1).
It has doubled. A test chip (on which an aluminum wiring pattern was formed) was sealed using the resin compositions [] and [] of Example 1 and Comparative Examples 1 and 2, and its reliability was evaluated. For molding, drop it directly onto the test chip to create a thickness of 1 mm and heat it at 85℃ for 30 minutes.
After drying at 110°C for 20 minutes, it was cured at normal pressure at 150°C for 30 minutes. These were left under steam at 121°C and 2 atm, and the corrosion level of the wiring was tested. The results are shown in Table-2. From the results in Table 2, it can be seen that Example 1 of the present invention is extremely resistant to moisture resistance tests. Example 2 and Comparative Example 3 To 45 parts of the resol type phenolic resin (A) prepared in Example 1, 100 parts of EocN102 (trade name of novolac type epoxy resin manufactured by Nippon Kayaku Co., Ltd.), 1.5 parts of catalyst imidazole C ₁₇ Z, and silica powder were added. 300 parts and 2 parts of carnauba wax were added and kneaded in a pressure kneader at 60°C for 20 minutes to prepare a semi-solid epoxy resin composition (Example 2). The same materials used in Example 2 were added to 45 parts of the novolak type phenolic resin (C) prepared in Comparative Example 2, then kneaded for 6 to 7 minutes with heated rolls at 60 to 80°C, cooled, and pulverized. An epoxy resin composition [] (Comparative Example 3) was created. These epoxy resin compositions [], [] were heated at 170°C to 180°C.
It was molded for 2 minutes at a pressure of 70 kg/cm ² , and its reliability was evaluated using a test chip as in Example 1. The results are shown in Table-3. The test method was to leave the product under 2 atmospheres of water vapor at 121°C. From the results in Table 3, it can be seen that the semiconductor devices sealed with the epoxy resin composition of the present invention are extremely good in the moisture resistance test, similar to the results in Table 2.

【table】

[Table] *1 The numerator indicates the number of defects and the denominator indicates the total number.

[Table] *2 The numerator indicates the number of defects, and the denominator indicates the total number.
As shown above, the epoxy resin composition for semiconductor encapsulation of the present invention has excellent moisture resistance and reliability.

Claims (1)

[Claims] 1 For epoxy resins, monovalent phenol-formaldehyde resins without substituents
An epoxy resin composition for semiconductor encapsulation, characterized in that it is blended with a resol type phenolic resin containing 5 to 25% by weight of a component with a molecular weight of 800 or more.