JP2006022240A - Resin composition and semiconductor device produced using the resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition having a good adhesion to Ni-Pd-plated lead frames and a reliable semiconductor device which does not cause peeling in a high temperature reflow process by using the resin composition for bonding the semiconductor device. <P>SOLUTION: The resin composition is an electroconductive adhesive to bond a semiconductor device to its support and contains (A) silver powder, (B) an epoxy resin, (C) a compound having two or more phenolic hydroxide groups in the molecule and (D) a compound expressed by general formula (1). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a resin composition and a semiconductor device manufactured using the resin composition.

As a part of environmental measures, lead removal from semiconductor products is being promoted, and the lead frame plating is increasingly changed to Ni-Pd for the purpose of deleading from the exterior plating of the semiconductor package. Here, Ni—Pd plating is thinly gold-plated (gold flash) for the purpose of improving the stability of the Pd layer on the surface. Generally, the Ni—Pd plating itself is smooth due to the smoothness of the Ni—Pd plating itself and the presence of gold on the surface. Compared to a silver-plated copper frame or the like, the adhesive strength of various members to the lead frame is reduced. In order to improve the adhesive strength, it is well known that a silane coupling agent having an amino group or a silane coupling agent having a mercapto group is generally used (see Patent Document 1). Also, since lead-free solder is used as the solder for mounting on the substrate, the reflow temperature needs to be higher than in the case of tin-lead solder. Due to an increase in stress due to a decrease in adhesive force and an increase in reflow temperature, the constituent material of the semiconductor package needs to have higher reflow resistance because peeling and cracking are likely to occur in the semiconductor package during reflow.
For this reason, not only high adhesiveness to Ni-Pd plating but also high adhesive reliability that does not cause peeling even when a high temperature reflow is applied to a resin composition for adhering a semiconductor element to a support. However, it has not been satisfactory with conventionally used resin compositions.
JP 09-199518 A

The present invention provides a resin composition having a good adhesive force with a lead frame plated with Ni—Pd, and the resin composition is used for bonding a semiconductor element, so that peeling does not occur even when high-temperature reflow is performed. The object is to provide a semiconductor device with excellent reliability.

Such an object is achieved by the present invention described in the following [1] to [3].
[1] A conductive adhesive for adhering a semiconductor element to a support, comprising (A) silver powder, (B) an epoxy resin, (C) a compound having two or more phenolic hydroxyl groups in one molecule, and (D ) A resin composition comprising a compound represented by the general formula (1),

[2] The compound represented by the general formula (1) is a compound in which R ¹ and R ³ are both ethoxy groups, a and b are both 3, n is 4, m1 and m2 are both 3 ] The resin composition according to item
[3] A semiconductor device manufactured using the resin composition according to [1] or [2],
It is.

According to the present invention, it becomes possible to provide a resin composition having a good adhesive force with a lead frame plated with Ni—Pd, and even if high temperature reflow is performed by using the resin composition for bonding a semiconductor element. It is possible to provide a highly reliable semiconductor product that does not peel.

  In the present invention, silver powder (A) is used as the filler. The reason for using silver powder is that it is excellent in conductivity and thermal conductivity. It can be used in combination with an alloy of silver and a metal other than silver, or an alloy of silver powder and silver and a metal other than silver. The proportion is preferably 90% by weight or more. In addition, since the field of use is related to semiconductors, it is necessary that there are few ionic impurities such as chlorine, sodium and potassium, and the average particle size is preferably 10 μm or less and the maximum particle size is preferably 50 μm or less. The shape is preferably a flake shape from the viewpoint of sedimentation during storage, but a spherical shape can also be used in combination. As such silver powder, those supplied for semiconductors can be easily obtained.

The content of the silver powder is not particularly limited, but is usually 70 to 90% by weight in the resin composition. This is because the conductivity is deteriorated below this, and the viscosity of the resin composition becomes too high below this, and the coating workability may be deteriorated.
In the present invention, an epoxy resin (B) and a compound (C) having two or more phenolic hydroxyl groups in one molecule are used as its curing agent. The epoxy resin is used because it has good adhesiveness, and the phenolic compound is used as the curing agent because the reaction product with the phenolic curing agent has the highest moisture resistance among various epoxy resins. is there. Both the epoxy resin (B) and the compound (C) having two or more phenolic hydroxyl groups in one molecule need to contain less ionic impurities as in the case of the silver powder. Usable epoxy resins (B) include bisphenol A, bisphenol F, biphenol and the like or bifunctional ones obtained by epoxidizing these derivatives, trihydroxyphenylmethane skeleton, trifunctional one having aminophenol skeleton, phenol novolac, Examples include, but are not limited to, polyfunctional compounds obtained by epoxidizing cresol novolac and the like, and since the resin composition needs to be liquid at room temperature, it is liquid alone or as a mixture at room temperature. Is preferred. It is also possible to use reactive diluents as is usual.

Examples of the compound (C) having two or more phenolic hydroxyl groups in one molecule that can be used include bisphenol A, bisphenol F, biphenol and the like, derivatives thereof, trihydroxyphenylmethane, trihydroxyphenylethane and the like, Examples thereof include, but are not limited to, phenol novolac resins, cresol novolac resins, phenol aralkyl resins, and biphenyl aralkyl resins.
In the present invention, it is possible to use a reaction catalyst of an epoxy compound and a phenol compound which are generally known, but those having a potential from the viewpoint of increasing the viscosity during storage are preferred. Examples include, but are not limited to, imidazoles having a melting point of 180 ° C. or higher, salts of triphenylphosphine or tetraphenylphosphine, salts of amine compounds such as diazabicycloundecene, and the like.

In the present invention, the compound (D) represented by the general formula (1) is further used. This is mainly for improving the adhesive strength with the adherend. In general, it is well known that adhesion is improved when a silane coupling agent having an amino group or a silane coupling agent having a mercapto group is used. For example, a phenolic curing agent is used for a silane coupling agent having an amino group. When used, it cannot be contained in an amount sufficient to exert an effect of improving the adhesive strength in order to promote the reaction at room temperature. In addition, when using a silane coupling agent having a mercapto group, although not as remarkable as a silane coupling agent having an amino group, the reaction is accelerated, and the deterioration of conductivity is observed due to the reaction with silver powder used as a filler. Therefore, a sufficient content cannot be added. On the other hand, since the compound (D) does not directly react with an epoxy group, a phenolic hydroxyl group, or silver at around room temperature and does not deteriorate the storage stability, it can contain a sufficient amount of an effect of improving the adhesive strength. It is possible to achieve both preservation and high adhesion in a phenol curing system. Further, the adhesive strength after curing is not significantly different from the case of using another highly adhesive type silane coupling agent, but is excellent in the maintenance rate of the adhesive strength after the moisture absorption treatment.
This is thought to be because the structure of-(S) n- in the molecule is chemically bonded to the metal on the lead frame surface and the silver powder surface used as a filler. -It is considered that the cohesive force of the cured resin is improved because the bond between the resins becomes strong. As an example of the compound (D) in FIGS. 1 and 2, A-1289 (manufactured by Nihon Unicar Co., Ltd., R ¹ and R ^{3 in} the general formula (1) are both ethoxy groups, a and b are both 3, n is 4, Both m1 and m2 are 3) a single DSC curve and a DSC curve of a sample in which A-1289 and silver powder are mixed at a weight ratio of 1: 1. The measurement conditions are a sample weight of about 30 mg and room temperature to 10 ° C./min. From these results, it can be confirmed that the compound (D) chemically reacts with the silver powder, and the effect of the present invention can be obtained only when used together with the silver powder.

For the above reason, n in the general formula (1) is limited to 2-4. This is because an improvement in adhesive strength cannot be expected even if the amount is less than this. Particularly preferred is the case where n is 4. The terminal has a form in which 1 to 3 alkoxy groups are bonded to Si in the same manner as a normal silane coupling agent. From the viewpoint of reactivity, the alkoxy group is preferably a methoxy, ethoxy, or butoxy group, and when it has more than 11 carbon atoms, it cannot be used because of poor reactivity. Particularly preferred is a methoxy group or an ethoxy group, and two or three bonded to Si. m1 and m2 are integers of 1 to 5, but 3 is particularly preferable.

The content of the compound (D) is 0.1 to 10% by weight based on the total of the epoxy resin (B) and the compound (C) having two or more phenolic hydroxyl groups in one molecule. If the amount is less than the lower limit, the expected effect of improving the adhesive strength cannot be expected. .

If necessary, additives such as a low stress agent, an antifoaming agent and a surfactant can be added to the resin composition of the present invention.
The resin composition of the present invention can be produced, for example, by premixing the components, kneading using three rolls, and degassing under vacuum.
As a method of manufacturing a semiconductor device using the resin composition of the present invention, a known method can be used.

[Examples 1, 2, and 3]
Flake silver powder (hereinafter referred to as silver powder) having a particle diameter of 1 to 30 μm and an average particle diameter of 3 μm as silver powder (A), and diglycidyl bisphenol A (epoxy equivalent 180, normal temperature) obtained by reaction of bisphenol A and epichlorohydrin as epoxy resin (B) Liquid, hereinafter bis A epoxy), cresyl glycidyl ether (epoxy equivalent 185, hereinafter CGE), phenol novolak (hydroxyl equivalent 104, softening point 80 to 80) as compound (C) having two or more phenolic hydroxyl groups in one molecule 90 ° C., phenol A) and phenol aralkyl resin (hydroxyl equivalent 180, manufactured by Sumitomo Bakelite Co., Ltd., PR-54869, phenol B), A-1289 as the compound (D) represented by the general formula (1) (Nippon Unicar Co., Ltd., is R ^1, R ³ of the general formula (1) Ethoxy group, a and b are both 3, n is 4, m1 and m2 are both 3, hereinafter referred to as coupling agent A), and Curesol 2MZ-A (manufactured by Shikoku Chemicals Co., Ltd., hereinafter referred to as 2MZ-) A) Dicyandiamide was blended in the ratio shown in Table 1, and kneaded with three rolls to obtain a resin composition.
The resin composition was defoamed at 2 mmHg for 30 minutes in a vacuum chamber, and then various performances were evaluated by the following methods.

[Comparative Examples 1, 2, 3, 4]
Resin compositions were prepared and evaluated in the same manner as in the examples. In Comparative Example 2, crushed silica (average particle size: 3 μm, hereinafter referred to as silica) was used. In Comparative Example 3, KBM-903 (manufactured by Shin-Etsu Chemical Co., Ltd., 3-aminopropyltrimethoxysilane) was used as a silane coupling agent having an amino group. Hereinafter, coupling agent B) is used as Comparative Example 4 as a silane coupling agent having a mercapto group, KBM-803P (manufactured by Shin-Etsu Chemical Co., Ltd., 3-mercaptopropyltrimethoxysilane),
Hereinafter, coupling agent C) was used.

Evaluation Method / Viscosity: Using an E-type viscometer (3 ° cone), the value at 25 ° C. and 2.5 rpm was measured after preparing the resin composition and after treating at 25 ° C. for 48 hours. Viscosity is 15-25 Pa. The case where the change rate of s and a viscosity was 20% or less was set as the pass. The unit of viscosity is Pa · s.
Adhesive strength: Using a resin composition, a 6 × 6 mm silicon chip was mounted on a Ni-Pd frame flashed with gold and cured in an oven at 175 ° C. for 30 minutes. After curing and after moisture absorption treatment (85 ° C., 85%, 72 hours), the hot die shear strength at 260 ° C. was measured using an automatic adhesive force measuring apparatus. The case where the die shear strength when heated at 260 ° C. was 30 N / chip or more was regarded as acceptable. The unit of adhesive strength is N / chip.
-Volume resistivity: The resin composition was applied so as to be 4 × 50 × 0.04 mm, and cured at 175 ° C. for 30 minutes. The volume resistivity was determined by measuring the resistance value in the length direction of 40 mm. 1 × 10 ⁻³ Ω · cm or less was regarded as acceptable. The unit is Ω · cm.
-Reflow resistance: Using the resin composition shown in Table 1, the following substrate and silicon chip were cured and bonded at 175 ° C. for 30 minutes, and sealed using a sealing material (Sumicon EME-7026, manufactured by Sumitomo Bakelite Co., Ltd.) After stopping and moisture absorption treatment at 60 ° C. and 60% relative humidity for 120 hours, IR reflow treatment (260 ° C., 10 seconds, 3 times reflow) was performed. The degree of peeling of the treated package was measured with an ultrasonic flaw detector (transmission type). The case where the peeling area of the die attach part was less than 10% was regarded as acceptable. The unit of the peeled area is%.
Package: QFP (14 x 20 x 2.0 mm)
Lead frame: Ni-Pd frame flashed with gold Chip size: 6 x 6 mm
Curing conditions: 175 ° C in oven, 30 minutes

According to the present invention, a resin composition having good adhesion to a lead frame plated with Ni—Pd is obtained, and a semiconductor device using the resin composition for bonding a semiconductor element is excellent in high-temperature reflow properties. It can be suitably used for semiconductor products compatible with lead-free solder.

It is a DSC curve of A-1289 which is an example of the compound (D) shown by General formula (1) used for this invention. It is a DSC curve of the mixture of the silver powder used for this invention, and A-1289 which is an example of the compound (D) shown by General formula (1).

Claims (3)

A conductive adhesive for adhering a semiconductor element to a support, comprising (A) silver powder, (B) an epoxy resin, (C) a compound having two or more phenolic hydroxyl groups in one molecule, and (D) a general formula A resin composition comprising the compound represented by (1).

The resin according to claim ¹ , wherein R ¹ and R ³ of the compound represented by the general formula (1) are both ethoxy groups, a and b are both 3, n is 4, m1 and m2 are both 3. Composition. A semiconductor device manufactured using the resin composition according to claim 1.

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