JP2008214381A - One-pack epoxy resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-pack epoxy resin composition for underfill sealing having sufficient repairing properties and excellent reworkability of a wiring substrate and exhibiting performance-improving effects as compared with those of a conventional technique in productivity, solvent cleaning properties, connection durability etc. <P>SOLUTION: The one-pack epoxy resin composition is used for the underfill sealing of a space between the wiring substrate and a semiconductor element electrically connected to the wiring substrate or a carrier substrate for holding the semiconductor element. The one-pack epoxy resin composition comprises an epoxy resin, an acid anhydride and a carboxylic acid represented by general formula (1): R<SP>1</SP>-O-CO-R<SP>2</SP>-COOH (wherein, R<SP>1</SP>is a 1-20C alkyl group or a 1-20C fluorinated alkyl group which may contain an ether bond, or an ester bond or a 6-20C aromatic hydrocarbon group; and R<SP>2</SP>represents a 1-20C chain or a cyclic bivalent hydrocarbon group). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a one-component epoxy resin composition excellent in repairability for underfill sealing between a semiconductor element and a wiring board or between a carrier substrate holding a semiconductor element and a wiring board.

  A semiconductor element is generally mounted on a wiring board through solder bumps such as solder balls. In addition, a semiconductor device such as an LSI mounted on a small substrate called a carrier substrate with fine wiring (this is generally referred to as CSP) may be mounted on a larger wiring substrate via solder bumps. It has been broken. A semiconductor element or a carrier substrate on which a semiconductor element is mounted is electrically and mechanically connected by a wiring board and a solder bump, but a gap between the wiring board and the semiconductor element or the carrier board generated by the solder bump is sealed with an epoxy resin or the like. Generally, it is underfill sealed with a resin.

  In this case, when a defect in the semiconductor element or a connection failure with the wiring board is found after inspection after mounting, the semiconductor element on the wiring board or the carrier substrate holding the semiconductor element is removed from the wiring board (repair this). Instead, it is desired from the viewpoint of production process yield and cost to regenerate the wiring board by attaching a new semiconductor element or the like (referred to as rework). For this purpose, the sealing resin can remove the semiconductor element or the like even after curing, and the resin residue remaining on the removed wiring board can be removed without causing wrinkles on the wiring board (this Such characteristics are referred to as having repairability.)

For example, Patent Document 1 discloses an epoxy resin composition that easily swells with an organic solvent using a fluorine-containing aromatic diamine as a curing agent. However, the fluorine-containing aromatic diamine has low reactivity with the epoxy resin and requires a long time for curing (for example, about 4 hours at 150 ° C.), which causes a problem in productivity of the semiconductor device. Patent Document 2 discloses an epoxy resin composition containing a plasticizer such as (meth) acrylic acid esters, aromatic or aliphatic esters. However, the use of such a plasticizer may cause a bleed-out problem and deterioration of characteristics of the semiconductor device. In addition, the inorganic filler cannot be blended sufficiently due to an increase in viscosity. Patent Document 3 discloses an acid anhydride curable epoxy resin composition using a xylene resin as a plasticizing component. However, this composition does not exhibit a satisfactory performance improvement effect in terms of repairability, solvent washability, connection durability, etc., and does not exhibit satisfactory reworkability.
JP 2002-60594 A JP-A-10-204259 Japanese Patent Laid-Open No. 2004-210965

  Therefore, the present invention has sufficient repairability, excellent reworkability of the wiring board, and can exhibit performance improvement effects compared to the prior art in productivity, solvent cleaning properties, connection durability, and the like. An object is to provide a one-component epoxy resin composition for fill sealing.

  As a result of intensive studies, the present inventor has found that the above problems can be solved by using an acid anhydride-cured epoxy resin composition containing a monocarboxylic acid compound having a specific structure, and has completed the present invention. .

That is, the present invention relates to an epoxy resin used for underfill sealing between a wiring board and a semiconductor element or a carrier substrate that holds the semiconductor element that is electrically connected to the wiring board. It is a one-component epoxy resin composition containing an acid anhydride and a carboxylic acid represented by the following general formula (1).
R ¹ —O—CO—R ² —COOH (1)
In the formula, R ¹ is an alkyl group having 1 to 20 carbon atoms and optionally containing an ether bond or an ester bond (however, all or part of the hydrogen atoms of the alkyl group may be substituted with fluorine atoms). Or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. R ² represents a linear or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms.

The present invention exhibits the following effects by the above-described configuration.
(1) The performance improvement effect is seen compared with the conventional product in repair property, solvent washability, connection durability, workability, and the like.
(2) There is no bleed out of the plasticizing component, and a sufficient amount of inorganic filler can be blended.
Hereinafter, the present invention will be described in detail.

  The epoxy resin in the composition of the present invention is not particularly limited as long as it is a monomer, oligomer or polymer having two or more epoxy groups in one molecule. The epoxy resin may not be liquid at normal temperature, but is preferably liquid at normal temperature. Specific examples of the epoxy resin include hydroquinone type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, and cresol novolak type. Examples thereof include an epoxy resin, a naphthol type epoxy resin, a triphenolmethane type epoxy resin, a dicyclopentadiene-modified phenol type epoxy resin, an isocyanuric acid type epoxy resin, and the like.

  In addition to the epoxy resin, a compound having one or more epoxy groups in one molecule and having a low viscosity at room temperature may be used as a reactive diluent. Examples of such compounds include t-butylphenyl glycidyl ether, glycerol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diester. Examples thereof include glycidyl ether and 1,9-nonanediol diglycidyl ether.

  The compounding amount of the compound having one or more epoxy groups in one molecule and having a low viscosity at room temperature is preferably less than 50% by weight based on the total amount with the epoxy resin. More preferably, it is 5 to 30% by weight.

  As the epoxy resin and the compound having one or more epoxy groups in one molecule and having a low viscosity at room temperature, those having a low impurity ion concentration are preferable.

  The acid anhydride in the composition of the present invention is not particularly limited as long as it is an acid anhydride used as a curing agent for an epoxy resin. For example, phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydroanhydride Phthalic acid, maleic anhydride, succinic anhydride, dodecenyl succinic anhydride, dichlorosuccinic anhydride, methyl nadic acid anhydride, pyromellitic anhydride, methylhexahydrophthalic anhydride, methylcyclohexenedicarboxylic anhydride, endomethylenetetrahydrophthalic anhydride, Methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, alkylstyrene-maleic anhydride copolymer, tetrabromophthalic anhydride, polyazeline acid anhydride, chlorendic acid anhydride, benzophenone anhydride A carboxylic acid. Among these, those which are liquid at normal temperature are preferable from the viewpoints of workability and characteristics after curing, and methyltetrahydrophthalic anhydride and methylhexahydrophthalic anhydride are particularly preferable.

  The blending amount of the acid anhydride is 0.8 to 1.2 equivalents per 1 equivalent of the epoxy resin, together with the acid equivalent of the carboxylic acid represented by the general formula (1) described in detail below. Is preferred. More preferably, it is 0.9 equivalent-1.1 equivalent. If the combined amount is less than 0.8 equivalent, the mechanical strength may not be sufficient. On the other hand, when the amount exceeds 1.2 equivalents, the viscosity of the composition is lowered, an uncured portion is likely to be formed, and the mechanical strength may be lowered.

The carboxylic acid in the composition of the present invention is represented by the following general formula (1).
R ¹ —O—CO—R ² —COOH (1)
In the formula, R ¹ is an alkyl group having 1 to 20 carbon atoms and optionally containing an ether bond or an ester bond (however, all or part of the hydrogen atoms of the alkyl group may be substituted with fluorine atoms). Or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. R ² is a linear or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms [for example, C 1 to C 20 alkylene (for example, methylene, ethylene, trimethylene, tetramethylene, propylene, etc.), etc. , C6-C20 alicyclic or aromatic hydrocarbon group (for example, a hydrocarbon group having a cyclohexane ring, dicyclopentane ring, cyclohexene ring, or benzene ring structure, which may have a lower alkyl substituent) ) Etc.].

Examples of the carboxylic acid include an alkyl group in which R ¹ is C1 to C20, preferably C3 to C14, more preferably C3 to C10, and an alkyl group including one or more ether bonds (for example, a C3 to C10 alkyl group). A group in which one or a plurality of ether bonds or ester bonds are bonded (for example, —CH ₂ CH ₂ OCH ₂ CH ₂ OCH _3, etc.), or all or part of the hydrogen atoms of the alkyl group are substituted with fluorine atoms A group (for example, a group in which all or part of the hydrogen atoms of a C3-C10 alkyl group are substituted with a fluorine atom, for example, —CH ₂ CF ₂ CF ₃ , —CH ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF _{2 H,} etc.), a phenyl group, R ² is an alicyclic hydrocarbon group or aromatic hydrocarbon group may have, for example, lower alkyl substituent, Shikurohe A cyclic divalent hydrocarbon group having a sun ring, dicyclopentane ring, cyclohexene ring, bicycloheptane ring, bicycloheptene ring or benzene ring structure, specifically, for example, a methyl group or an ethyl group as a substituent. A hydrocarbon group having a cyclohexane ring, a dicyclopentane ring, a cyclohexene ring, a bicycloheptane ring, a bicycloheptene ring, a benzene ring structure, or the like, and R ¹ and R ² are any of these groups Any of the carboxylic acids obtained in combination can be suitably used. Such a carboxylic acid can be obtained, for example, by esterification of an aromatic dicarboxylic acid such as phthalic acid or hydrogenated phthalic acid.

  As described above, the total amount of the acid anhydride and the carboxylic acid is within the above range, and the number of moles of the carboxylic acid / number of moles of the acid anhydride = 0.1-0. 0.5, more preferably a ratio of 0.2 to 0.4.

  In the composition of the present invention, a reaction accelerator can be used as necessary. As the reaction accelerator, a latent accelerator is preferable from the viewpoint of a one-component property. Examples of such a reaction accelerator include adduct compounds. Specifically, for example, Amicure PN-23 (commodity) Name), Amicure MY-24 (trade name), Fuji Cure FX-1000 (trade name), and the like. The amount used is about 1 to 10 parts by weight per 100 parts by weight of the epoxy resin.

  An inorganic filler can be blended in the composition of the present invention. The inorganic filler preferably has an average particle diameter of 0.1 to 10 μm, more preferably 0.3 to 4 μm. When the average particle size is less than 0.1 μm, the viscosity of the composition increases, thixotropy occurs, and the infiltration rate decreases. If the average particle size exceeds 10 μm, the gap between the semiconductor element and the substrate may be clogged during underfill.

Moreover, it is preferable that the specific surface area of an inorganic filler is 0.5-10 m < ² > / g, and 1-8 m < ² > / g is more preferable. When the specific surface area is less than 0.5 m ² / g, the infiltration rate is increased, but the separation of the filler and the liquid component occurs, and the effect of improving the mechanical strength of the cured product and reducing the generated stress is stably exhibited. Can not. If the specific surface area exceeds 10 m ² / g, thixotropy occurs and the infiltration rate may be reduced.

  Specific examples of the inorganic filler include, for example, fused silica, crystalline silica, synthetic silica (for example, a gas phase method, a sol-gel method, a sodium silicate method, etc.), alumina, silicon nitride, and aluminum nitride. Etc. Among these, synthetic silica is preferable in terms of purity, and spherical ones are preferable from the viewpoint of obtaining excellent penetration into gaps because the viscosity upon addition is low.

  In the composition of the present invention, the amount of the inorganic filler added is preferably 30 to 80% by weight in the composition. If it is less than 30% by weight, the coefficient of thermal expansion increases, the stress at the interface between the semiconductor element or bump and the underfill resin increases, and the risk of peeling and cracking increases. If it exceeds 80% by weight, the viscosity of the composition increases, and the infiltration rate may decrease. More preferably, it is 50 to 65% by weight.

  In the composition of the present invention, other additives can be used as necessary as long as the object of the present invention is not impaired. As said other additive, a silane coupling agent, carbon black (coloring agent), an antifoamer, a leveling agent, an acrylic resin, a xylene resin, a butadiene-acrylonitrile copolymer etc. can be mentioned, for example.

  The blending amount of the above other additives depends on the kind of the additive, but is generally preferably 0.5 to 10% by weight in the composition of the present invention.

  In the composition of the present invention, each of the above-described components is added to a predetermined amount, for example, 40 to 110 parts by weight of an acid anhydride and 100% by weight of the carboxylic acid 10 represented by the general formula (1) per 100 parts by weight of the epoxy resin. -50 parts by weight, and if necessary, an inorganic filler can be suitably produced by sufficiently mixing with a mixer. Examples of the mixer include a three roll mill, a twin screw mixer, a rotary mixer, a pot mill, and a planetary mixer.

  The composition of the present invention fills and seals a gap between a semiconductor element or a carrier substrate and a wiring board in order to protect a bump which is a connection part between the semiconductor element or a carrier substrate holding the semiconductor element and the wiring board. As a result, a semiconductor device using a flip chip is used as an underfill resin for reinforcing bump connection strength in mounting of BGA and CSP, which are IC packages in which solder balls are arranged in a grid. Can be manufactured. Examples of such a semiconductor device include various semiconductor devices used for mobile devices, in-vehicle devices, and the like. Since the composition of the present invention can be made liquid at room temperature, it can be filled at room temperature (about 25 ° C.) using a dispenser. In general, the resin is filled at room temperature to about 120 ° C. Can be done. At this time, it is preferable that a side portion around the chip spreads in a skirt shape to form a so-called fillet. As curing conditions, for example, 120 to 170 ° C. and 1 to 10 hours can be applied, but short-time curing of about 1 to 2 hours is preferable.

  When a semiconductor device using the composition of the present invention is repaired, generally, the following is performed. That is, by using a hot platen or the like to heat a portion to be repaired of the semiconductor element or carrier substrate or wiring board so as to be higher than the melting point of the solder, that is, about 220 to 260 ° C. Can be easily peeled off. At this time, since the composition of the present invention contains a monofunctional carboxylic acid, the degree of cross-linking of the cured product can be moderately suppressed, so that it can be easily peeled off from the wiring board. Thereafter, the epoxy resin residue on the wiring board is preferably immersed in an organic solvent (for example, N-methylpyrrolidone) at a temperature of about 70 to 150 ° C. for about 30 minutes to 2 hours, swollen and removed, The wiring board can be regenerated. Under the present circumstances, since the composition of this invention contains the said carboxylic acid, a resin residue can be easily removed by the plasticization effect. Further, the removed semiconductor element can be reused if necessary by removing the remaining epoxy resin with an organic solvent.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Examples 1-11, Comparative Examples 1-2
All components were charged according to the formulation shown in Table 1 and mixed at room temperature for about 2 hours using a planetary mixer. Thereafter, the solid was further uniformly dispersed with three rolls to prepare a one-component epoxy resin composition. The components in Table 1 are as follows.
Epoxy resin: High-purity bisphenol A type epoxy resin, epoxy equivalent 185 g / eq, viscosity 10 Pas, hydrolyzable chlorine content 20 ppm
Acid anhydride: 4-methylhexahydrophthalic anhydride, acid anhydride equivalent 170 g / eq, viscosity 70 mPas
Xylene resin: Nikanol LLL manufactured by Fudou
Reaction accelerator: Amicure MY24 (Ajinomoto Fine Techno Co., Ltd.)
Inorganic filler: spherical synthetic silica, average particle size 0.5 μm, specific surface area 5.5 m ² / g
Carboxylic acid compounds 1 to 10: Compound (1) below (acid equivalent 242 g / eq), compound (2) (acid equivalent 270 g / eq), compound (3) (acid equivalent 298 g / eq), compound (4) ( Acid equivalent 276 g / eq), compound (5) (acid equivalent 288 g / eq), compound (6) (acid equivalent 313 g / eq), compound (7) (acid equivalent 392 g / eq), compound (8) (acid equivalent) 268 g / eq), compound (9) (acid equivalent 282 g / eq), compound (10) (acid equivalent 336 g / eq). However, in the compound (10) is _{Ra + Rb + Rc = C 6} H 12.

Evaluation Method The obtained epoxy resin composition was evaluated by the following method. The results are shown in Table 1.
The following were used as a simulated semiconductor chip and wiring board.
Simulated semiconductor chip: with polyimide passivation film, 15 x 15 x 0.4 mm
Bump: Ag / Sn lead-free solder bump, diameter 400 μm, 800 μm pitch, number of bumps 256
Wiring board: 20 × 20 × 0.8 mm, Glass Epochin FR4, Solder resist uses Tamura's DSR2200SPM103N Evaluation item Gap penetration: Measures the time until the resin has entered the gap on a hot plate at 80 ° C did. The case where the intrusion was completed within 60 seconds was evaluated as ○, and the case where it took 60 seconds or more was evaluated as ×.
Viscosity change rate: A value obtained by dividing the composition viscosity after standing for 24 hours at 25 ° C. by the initial viscosity is defined as a viscosity change rate. The viscosity was measured at 25 ° C. with an HBT type rotational viscometer. In addition, if a viscosity change rate is 2.0 or less, it can be used as a one-component epoxy resin.
Repairability: The cured resin was cured at 150 ° C. for 1 hour, then heated on a hot plate at 260 ° C. for 15 seconds, and then a paper knife was quickly inserted between the chip and the substrate to separate the chip. A substrate that has almost no residual underfill resin on the substrate and that does not peel off the solder resist on the substrate. The residual underfill resin on the substrate is 30% or less of the chip area, and the solder resist on the substrate is not removed. The ones that were not peeled off were marked with ◯, and the ones where the underfill resin remained on the substrate was 30% or more of the chip area or the solder resist on the substrate was peeled off.
Solvent detergency: The chip on which the underfill resin adhered and remained after the repair test was immersed in N-methylpyrrolidone, and the peelability after 1 hour at 120 ° C. was observed. The resin is peeled off from the chip cleanly on the entire chip bonding surface, and the resin is peeled off from the chip at 90% or more of the area of the chip bonding surface, and the residue can be removed by lightly rubbing with a cotton swab. The case where 10% or more and less than 50% of the area of the chip adhesion surface remained on the chip was indicated by Δ, and the case where the resin remained on the chip at 50% or more of the area of the chip adhesion surface was indicated by x.
Connection durability: A thermal cycle test (1000 cycles of −55 ° C. for 15 minutes / 125 ° C. for 15 minutes) was performed on a sample that had been infiltrated with resin and cured at 150 ° C. for 1 hour. After the thermal cycle test, interfacial peeling and cracks between the resin and solder bumps were observed by an ultrasonic flaw detector (SAT) and SEM observation of the cross section. Those without peeling and cracks were marked with ◯, and those with no peeling were marked with x.

  In each of Examples 1 to 11, compared with Comparative Examples 1 and 2 corresponding to the prior art, there was a performance improvement effect in repairability, solvent cleaning properties, connection durability, and the like. Incidentally, Comparative Example 2 contains a xylene resin, and the performance is superior in terms of repairability and the like than Comparative Example 1, but the composition of the present invention clearly shows further performance improvement effects in these performances. It was.

Claims (5)

An epoxy resin, an acid anhydride, and an epoxy resin used for underfill sealing between a wiring board and a semiconductor element or a carrier board that holds the semiconductor element that is electrically connected to the wiring board, and A one-component epoxy resin composition containing a carboxylic acid represented by the following general formula (1).
R ¹ —O—CO—R ² —COOH (1)
(In the formula, R ¹ is an alkyl group having 1 to 20 carbon atoms and optionally containing an ether bond or an ester bond (provided that all or part of the hydrogen atoms of the alkyl group may be substituted with fluorine atoms). Or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and R ² represents a linear or cyclic divalent hydrocarbon group having 1 to 20 carbon atoms.) The composition according to claim 1, wherein R ² is an alicyclic hydrocarbon group or an aromatic hydrocarbon group. The composition according to claim 2, wherein R ² is a cyclic divalent hydrocarbon group having a cyclohexane ring, a dicyclopentane ring, a cyclohexene ring, or a benzene ring structure, which may have a lower alkyl substituent. object. The composition according to any one of claims 1 to 3, comprising 40 to 110 parts by weight of an acid anhydride and 10 to 50 parts by weight of a carboxylic acid represented by the general formula (1) with respect to 100 parts by weight of the epoxy resin. object. Furthermore, the composition in any one of Claims 1-4 which contains 30-80 weight% of inorganic fillers.