KR100479857B1 - Silicon resin composition for packaging semiconductor - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid silicone resin compositions used to fill gaps between chips and substrates or to bond chip edges and substrates in connection with chip scale packaging (CSP) or ball grid array (BGA) packaging technologies. Preferably (1) socked vinyl polydialkylsiloxane resin; (2) polyvinyl siloxane resin; (3) hydrosiloxane curing agents; (4) curing reaction inhibitors; (5) tackifying silane additives; (6) addition-curing platinum catalyst conjugates; And (7) spherical silica having a particle diameter of 5 to 50 microns and fused spherical silica having a spherical silica having a particle diameter of 1 micron or less in a ratio of 50/50 to 90/10, and a silicone resin composition for a semiconductor package. When the resin composition of the present invention is applied to a micro BGA package, it is possible to secure stable workability and excellent reliability characteristics.

Description

Silicone resin composition for semiconductor package {SILICON RESIN COMPOSITION FOR PACKAGING SEMICONDUCTOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid silicone resin compositions used to fill gaps between chips and substrates or to bond chip edges and substrates in connection with chip scale packaging (CSP) or ball grid array (BGA) packaging technologies. In particular, the present invention relates to a liquid silicone resin composition having excellent viscosity characteristics, which enables to rapidly fill a space between a chip and a substrate, and also ensures high reliability, low temperature elastic modulus, and low thermal expansion coefficient.

The trend toward miniaturization, thinning, and high performance electronics has been accelerating in recent years. Portable terminals and notebook PCs are a good example. Accordingly, the size of IC packages mounted as core components in electronic products has also been miniaturized, thinned and highly integrated. In order to cope with reducing the size of the bare chip itself, CSP and BGA packaging methods are most widely used. In the BGA package, Tessera's micro BGA uses a flexible resin-based substrate as a semiconductor chip carrier and connects the circuit on the chip and the chip carrier by bumps, wires or leads, wherein the chip and the chip It is necessary to seal or fill with resin in order to protect the gap between the carriers, i.e., the surface of the chip and the portions where the wires or leads are exposed.

However, in the thermal shock test of the resin-filled package, the connection of the lead or the wire connected with the chip and the wiring on the chip carrier due to the stress generated by the different coefficients of thermal expansion such as resin, chip, circuit board, lead, wire, etc. There is a high possibility of poor reliability due to cutting of the part or the part of the lead or wire itself or cutting of the middle part. In order to eliminate the possibility of such a reliability failure, it can be said that the selection of a resin to be filled or sealed is important.

In general, epoxy resins are the most widely used resins for sealing or encapsulating semiconductor chips and packages. However, it is well known that epoxy resins are not preferable for packages requiring thermal stability at low temperatures, i.e. cold resistance, and especially for highly reliable packages having a temperature range of -50 degrees below the thermal shock test. It is impossible to use due to the elastic modulus. In order to compensate for the disadvantages of the epoxy resin, a rubber (rubber) may be used as a polymer additive, but there is a limit in reducing the elastic modulus at low temperatures.

The silicone resin can compensate for the shortcomings of the epoxy resin for general semiconductor sealing. In the case of silicone, the glass transition temperature is lower than -100 degrees due to the resin property, and thus the rubber property is maintained at temperatures above -100 degrees unlike the epoxy resin. Therefore, it is excellent in cold resistance at low temperature and can be more reliable when using epoxy resin.

In general, there are two types of silicone resin compositions, condensation-curable and addition-curable, but in the case of condensation-curable, the addition product volatilizes to generate voids, which may result in poor package reliability. This is suitable.

In the addition-curable silicone resin composition, a polysiloxane resin having a vinyl group and a polysiloxane having a hydrosilyl group are most widely used as the resin and the curing agent component, respectively. The development of addition-curable silicone resin compositions has become more active in recent years, particularly for the purpose of encapsulating semiconductors (see Japanese Patent Application Laid-Open Nos. 2000-63630, 2000-169714, 2000-176695, 2000-265067, 2000-265150, 2000-297125, 2000-327921, 1999-181289, 1998-60282, 1997-111127, United States Patent No. 6124407, 6001943, 5908878, No. 6001918, etc.), it is necessary to improve the disadvantages that the adhesion and mechanical strength is inferior to the use of epoxy resin due to the inherent properties of silicone resin, and especially for the purpose of semiconductor encapsulation, excellent viscosity characteristics for fairness and dischargeability It is necessary to secure a low coefficient of thermal expansion and low temperature elastic modulus for reliability.

The present invention is to solve the problems of the prior art as described above, an object of the present invention is to provide a liquid silicone resin composition excellent in workability and adhesive strength, particularly low thermal expansion coefficient and low temperature elastic modulus suitable for high reliability semiconductor package.

That is, the present invention provides a silicone resin composition for a semiconductor package comprising the following components:

(1) socked end vinyl polydialkylsiloxane resin;

(2) polyvinyl siloxane resin;

(3) hydrosiloxane curing agents;

(4) curing reaction inhibitors;

(5) tackifying silane additives;

(6) addition-curing platinum catalyst conjugates; And

(7) A fused spherical silica in which spherical silica having a particle size of 5 to 50 microns and spherical silica having a particle size of 1 micron or less are mixed at a ratio of 50/50 to 90/10.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to achieve the said objective, the present inventors introduced the polyfunctional siloxane resin into an addition-curable silicone resin composition, reducing the elasticity modulus at low temperature by controlling the degree of crosslinking, and improving the cold resistance of a package, The addition of a system compound increases the adhesion to the substrate, and at the same time, it is successful to secure a low coefficient of thermal expansion while maintaining low viscosity and low plasticity by filling spherical silicas of different sizes.

Hereinafter, the present invention will be described in more detail.

The silicone resin used as the base resin in the present invention is a polydialkylsiloxane resin (component 1) having a structure represented by the following formula (1), and has a vinyl functional group at the end of the sock.

(Wherein R is a methyl, ethyl or propyl group, preferably methyl group and R at each position may be the same or different)

The vinyl equivalent weight of said sock-end vinyl polydialkylsiloxane resin is 10,000-200,000 g / mol, Preferably it is 10,000-50,000 g / mol. In addition, the viscosity of the resin is 100 to 100,000 cps, preferably 1,000 to 50,000 cps, it can be used by mixing two or more kinds of low molecular weight and high molecular weight siloxane resin for viscosity control of the final composition. It is preferable that content of the component (1) in the resin composition of this invention is 20-50 weight%.

An important feature of the present invention is to increase the mechanical strength by increasing the degree of crosslinking, and furthermore to inhibit the crystallization of alkylsiloxanes to reduce the elastic modulus at low temperatures (ie, to increase the cold resistance). In the present invention, a siloxane resin (component 2) containing a large amount of vinyl groups is used for this purpose, and the polyvinyl siloxane resin may be a polyvinyl Q resin having a structure of Formula 2 and / or a structure of Formula 3 It is possible to use vinylalkylsiloxane-dialkylsiloxane copolymers having.

(Wherein R is a methyl, ethyl or propyl group, preferably methyl group and R at each position may be the same or different)

At this time, since the polyvinyl Q resin of the formula (2) has a three-dimensional radial structure and not a straight chain and is a solid phase, it is used by blending with the component (1). The vinyl content of the polyvinyl Q resin used in the present invention is 0.1-5 mmole / g, and the viscosity is 1,000-50,000 cps.

Meanwhile, as the vinylalkylsiloxane-dialkylsiloxane copolymer of Chemical Formula 3, a resin having a vinylalkylsiloxane content of 0.5 to 20 mole% and preferably 1 to 5 mole% in a resin is used, wherein the resin has a viscosity of 100 200,000 cps, preferably 1,000-50,000 cps.

As mentioned above, in the present invention, the polyvinyl Q resin and the vinylalkylsiloxane-dialkylsiloxane copolymer may be mixed and used as a crosslinking degree adjusting resin, and in this case, mixed use considering the vinyl equivalent of each resin. do.

It is preferable that content of the component (2) in the resin composition of this invention is 4-30 weight%. When the content of component (2) is less than 4% by weight of the total resin composition, it is difficult to secure a low-temperature elastic modulus (less than 100 MPa at -50 degrees Celsius) to meet the required reliability level, and in particular, the vinylalkylsiloxane of the general formula (3) In the case of the -dialkyl siloxane copolymer, the vinyl group content is significantly higher than that of the polyvinyl Q resin of Formula 2, so that the vinyl alkylsiloxane-dialkylsiloxane copolymer having a vinylalkylsiloxane content of more than 5 mole% is used as the total resin composition. When used in an amount of more than 30% by weight of the crosslinking may cause excessive brittleness of the physical properties after curing of the composition due to excessive increase in the degree of crosslinking.

In the present invention, an addition reaction curing agent (component 3) containing a hydrosilyl group is used as the curing agent, and in the present invention, as the hydrosiloxane curing agent, an alkylhydrosiloxane-dialkylsiloxane copolymer having the structure of Formula 4 below, Alkylhydrosiloxane having a structure, and Q structure hydrosiloxane having a structure of formula (6) is used either alone or in combination of two or more kinds, preferably of the formula (4) Alkylhydrosiloxane-dialkylsiloxane copolymers are used.

(Wherein R is a methyl, ethyl or propyl group, preferably methyl group and R at each position may be the same or different)

(Wherein R is a methyl, ethyl or propyl group, preferably a methyl group and R at each position may be the same or different; R 'is a hydrogen atom or a methyl group)

The alkylhydrosiloxane content of this hydrosiloxane hardener is 0.5-50 mole%, preferably 5-20 mole%. The viscosity of the hydrosiloxane curing agent used in the present invention is 10 to 20,000 cps, preferably 10 to 500 cps, it is possible to use a mixture of low viscosity and high viscosity for viscosity control. Component (3) is used in the ratio of 0.5-5 mol, preferably 1-3 mol with respect to 1 mol of vinyl group content of the said components (1) and (2).

In the present invention, the curing reaction of the resin composition is a hydrosilylation reaction by a platinum catalyst, and the rapid curing reaction is possible even at room temperature due to the characteristics of the reaction, and there is a serious problem in workability when there is no separate curing reaction inhibitor. In order to secure sufficient working time, it is necessary to extend the pot life. For this purpose, the present invention uses divinyltetramethyldisiloxane of formula (7) or 3-butyn-1-ol of formula (8), known as hydrosilylation reaction inhibitor (component 4).

The amount of component (4) used corresponds to 0.1 to 10% by weight, preferably 0.1 to 5% by weight of the total composition.

In this invention, the silane compound (component 5) which has a structure of following General formula (9) is used for the purpose of improving the adhesive force with respect to the base material of a resin composition.

(Wherein R is a methyl or ethyl group; X is a vinyl, allyl, glycidyloxy or methacryloxy group)

As can be seen in Formula 9, the adhesive imparting additive used in the present invention is a silane compound having a vinyl group, allyl group, glycidyloxy group or methacryl group and at the same time containing an alkoxy group. In the present invention, any one of these silane compounds may be used alone, but preferably two or more kinds are used in combination. Although the addition amount of component (5) is suitably determined in the range which does not reduce the other characteristic, hardening rate, etc. of the resin composition of this invention, Preferably it is used in 0.1-5 weight% of the whole composition.

In the present invention, a platinum catalyst (component 6) is used as a curing reaction catalyst of the resin component, and in consideration of stability at room temperature, a complex with divinyl tetramethyldisiloxane is used, and the structure thereof is represented by the following chemical formula (10). Component (6) is used such that the concentration in the total resin composition is 5-100 ppm, preferably 5-50 ppm.

In addition, in the present invention, fused spherical silica (component 7) is used as an inorganic filler for the purpose of increasing the strength of the final resin composition and reducing the coefficient of thermal expansion, and the particle size and particle size distribution of silica have a significant effect on the viscosity characteristics of the resin composition. Therefore, it is necessary to select silica in consideration of viscosity characteristics. In the present invention, the maximum particle diameter of the silica is limited to 50 microns, but by using a mixture of silica having an average particle diameter of 5 microns or more and silica having an average particle diameter of 1 micron or less, a very good viscosity characteristic can be obtained.

The total content of component (7) in the resin composition of the present invention is 50 to 60% by weight, wherein the mixing ratio of 5 micron or more silica and 1 micron or less silica is 50/50 to 90/10, preferably 70/30 to It should be 90/10. In the present invention, the filling efficiency can be improved by using a mixture of spherical silicas having different sizes, and as a result, lower viscosity and lower ductility can be obtained than when using large silica or small silica. Therefore, the gap filling time between the chip and the carrier is faster and the dischargeability is improved, and thus, a great efficiency increase in workability and processability can be expected.

In addition, especially when used in a package that requires high reliability, the silica content in the resin composition is increased, the purity of the silica itself is important. In consideration of this point, in the present invention, silica having a Na and Cl ion content of 1 ppm or less is used, and in particular, silica or a U or Th content of 1 ppb or less is used in consideration of generation of γ-rays.

In addition to the components (1) to (7) described above, when it is necessary to color the resin composition of the present invention in black or other colors, carbon black, organic or inorganic dyes, etc. may be added in an appropriate amount depending on the desired degree of coloring. If the carbon black is used in excess of 5% by weight of the total resin composition may cause problems in flowability or dispersibility, it should be used in less than 5% by weight. The difference in the degree of coloring occurs depending on the type of carbon black or dye, but can be adjusted by increasing or decreasing the amount of use, and therefore, the type of pigment / dye is not particularly limited. In addition, in the case of packages requiring high reliability, a pigment is used without the use of dyes, and most commonly carbon black is used.

In addition, a flame retardant, a heat conductive filler, etc. can be further added to the resin composition of this invention according to a use of a package.

The liquid silicone resin composition of the present invention may be prepared by stirring, mixing, or dispersing the above-described components simultaneously or sequentially by raw materials, as needed, but generally, the catalyst is not stirred at the same time because the curing reaction is caused by heat. Do not. The apparatus required for the mixing, stirring, dispersion, and the like is not particularly limited, and a conventional mixing grinder, a three roll mill, a ball mill, a planetary mixer, etc., equipped with a stirring, heating, cooling, and vacuum apparatus, may be used. May be used in combination as appropriate.

The viscosity of the liquid silicone resin composition of the present invention prepared as described above should be 50,000 cps or less at 25 ° C., preferably 8,000 to 15,000 cps or less. If the viscosity exceeds 50,000 cps, workability in the ejection process performed under normal conditions (needle size and pressure) during package molding becomes poor, and in particular, the rate of filling the gap between the chip and the substrate is excessively delayed. A significant decrease in fairness is caused. The curing after molding is preferably cured in an oven at 150 ° C. for 0.5 hours or more. In addition to the advantages described above, the silicone resin composition of the present invention does not use any solvents or volatile raw materials, and thus, there is no possibility that poor reliability such as voids may occur even after curing.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example  And Comparative example

The composition, physical properties, workability and reliability evaluation results of the silicone resin compositions according to Examples and Comparative Examples are summarized in Table 1 below.

Composition Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Base resin Divinylpolydimethylsiloxane ¹⁾ 28.8 36.7 32.4 28.1 28.8 28.8 43.7 42.0 Crosslinking degree adjusting resin Vinyl Q resin ²⁾ 13.9 - 2.0 12.1 13.9 13.9 - 3.2 Vinyl methylsiloxane copolymer ³⁾ - 4.1 6.1 - - - - Hardener Hydromethylsiloxane copolymer ⁴⁾ 3.8 5.7 6.0 6.3 3.8 3.8 2.8 3.3 Silica Average particle size 5 microns 40.0 45.0 35.0 40.0 25.0 30.0 40.0 40.0 Average particle size 1 micron 10.0 5.0 15.0 10.0 25.0 20.0 10.0 10.0 Silane additive Vinyltrimethoxysilane 1.0 - - - 1.0 1.0 - 1.0 Allyltrimethoxysilane - 1.0 1.0 1.0 - - 1.0 - Glycidyloxysilane 1.0 - 1.0 1.0 1.0 1.0 - - Methacryloxysilane - 1.0 - - - - 1.0 - Curing reaction inhibitor Divinyltetramethyldisiloxane 1.0 1.0 1.0 1.0 1.0 1.0 1.0 - Carbon black 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Platinum Catalyst (ppm) 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 system 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Property evaluation result Viscosity (cps, 25 ℃) 12,000 14,000 12,600 10,800 22,500 25,900 21,200 18,500 Thermal expansion coefficient α (ppm / ℃) 198 195 192 193 202 205 235 226 Tensile Strength (MPa) 5.6 6.1 7.2 6.6 5.5 5.8 3.2 3.6 Low Temperature Modulus (MPa) 90 87 82 84 89 92 165 147 Adhesive (kgf) 8.2 7.9 7.5 7.6 7.9 8.1 7.7 2.4 Workability Evaluation Results Dischargeability (G = good, M = medium, P = poor) G G G G P P P M Gap filling time (min) 90 120 100 87 390 210 270 200 Reliability Evaluation Results TC (PASS%) 100 100 100 100 100 100 92 95

¹⁾ Molecular weight 50,000 g / mol, 25 ° C viscosity 5,000 cps, Vinyl content 0.05 mmole / g

²⁾ viscosity at 25 ° C 1,000 cps, vinyl content 0.25 mmole / g

³⁾ 25 ℃ viscosity 1,000 cps, vinyl methylsiloxane content 4.0 mole%

⁴⁾ 25 ° C viscosity 30 cps, hydromethylsiloxane content 15 mole%

[Method of property and reliability evaluation]

1) viscosity

Measurement at 25 ° C using Cone & Plate type Brookfield Viscometer

2) coefficient of thermal expansion

    Evaluation by TMA (Thermomechanical Analyser)

3) tensile strength

    Evaluation according to ASTM D412 using Universal Test Machine (UTM)

4) Low temperature modulus

   Elastic modulus at -50 degrees of 0.4mm thick film-formed specimens measured by DMA (Dynamic Mechanical Analyzer)

5) Adhesive

   LAP SHEAR TEST: Use UTM to check the adhesion of PI film bonded at width x length = 1 cm x 1 cm

6) Dischargeability

   Disconnected when dispensed at needle size 23G and discharge pressure 50ps using dispenser

   To check a certain amount of discharge

7) gap filling time

   Time to reach the opposite gap inlet when a certain amount of resin composition is discharged into the gap inlet of 0.7 mm width and 0.3 mm thickness between the chip and the glass plate

8) Reliability (Heat Resistance)

   Peel off and observe wire breakage after TC (Thermo Cycle: -65 ~ 150 ℃, 1000 cycle)

As can be seen from the comparison of Examples 1 to 4 and Comparative Examples 3 to 4 in Table 1, the low-temperature elastic modulus of the composition and the reliability test results according to the mixing amount of the polyvinyl siloxane resin having the structures of Formula 2 and Formula 3 It was confirmed that the change, and the addition of more than 4% by weight of polyvinyl siloxane resin proved to have a good effect on the increase in mechanical strength, such as tensile strength of the composition. That is, it can be concluded that the mechanical properties and the reliability-related characteristics of the resin composition are simultaneously improved or decreased depending on whether the polyvinyl siloxane resin is mixed or used.

On the other hand, in Example 1 and Comparative Examples 1 and 2, the total content of silica was the same, but when changing the mixing ratio of the silica of 5 microns or more and 1 micron or less, there was a change in the viscosity characteristics of the composition, thereby discharging and It was observed that the gap filling speed was greatly affected. In addition, the coefficient of thermal expansion of the silicone resin composition was increased or decreased in inverse proportion to the increase or decrease of the silica content, but not shown in Table 1, and the silica was not less than 50 wt% and not more than 60 wt% of the total composition. When used, the best results were obtained without any other deterioration of the viscosity characteristics.

As described in detail above, when the resin composition of the present invention is applied to a micro BGA package, it is possible to secure stable workability and excellent reliability characteristics.

Claims (8)

Silicone resin composition for a semiconductor package comprising the following components: (1) socked end vinyl polydialkylsiloxane resin; (2) polyvinyl siloxane resin; (3) hydrosiloxane curing agents; (4) curing reaction inhibitors; (5) tackifying silane additives; (6) addition-curing platinum catalyst conjugates; And (7) A fused spherical silica in which spherical silica having a particle size of 5 to 50 microns and spherical silica having a particle size of 1 micron or less are mixed at a ratio of 50/50 to 90/10. The silicon for semiconductor package according to claim 1, wherein the sock-end vinyl polydialkylsiloxane resin comprises 20 to 50% by weight of at least one resin having a structure of the following Chemical Formula 1 and having a viscosity of 100 to 100,000 cps. Resin composition: [Formula 1] (Wherein R is a methyl, ethyl or propyl group and R at each position may be the same or different) The polyvinyl siloxane resin according to claim 1, wherein the polyvinyl siloxane resin has a structure of formula (2) and has a viscosity of 1,000 to 50,000 cps and / or a vinylalkylsiloxane having a structure of formula (3) and a viscosity of 100 to 200,000 cps. -Silicone resin composition for a semiconductor package comprising 4 to 30% by weight of a dialkylsiloxane copolymer: [Formula 2] [Formula 3] (Wherein R is a methyl, ethyl or propyl group and R at each position may be the same or different) According to claim 1, wherein the hydrosiloxane curing agent having a structure of formula (4) and a viscosity of 10 to 20,000 cps alkylhydrosiloxane-dialkylsiloxane copolymer, the structure of the formula (5) alkyl having a viscosity of 10 to 20,000 cps And at least one resin selected from the group consisting of a hydrosiloxane and a Q structure hydrosiloxane having a structure of the formula (6) and having a viscosity of 10 to 20,000 cps: 0.5 per mole of vinyl group content of the components (1) and (2) Silicone resin composition for semiconductor packages comprising a ratio of ~ 5 mol: [Formula 4] (Wherein R is a methyl, ethyl or propyl group and R at each position may be the same or different) [Formula 5] (Wherein R is a methyl, ethyl or propyl group and R at each position may be the same or different; R 'is a hydrogen atom or a methyl group) [Formula 6] According to claim 1, wherein the curing reaction inhibitor comprises divinyl tetramethyl disiloxane having a structure of formula (7) or 3-butyn-1-ol having a structure of formula (8) to 0.1 to 10% by weight Silicone resin composition for semiconductor package: [Formula 7] [Formula 8] The silicone resin composition for a semiconductor package according to claim 1, further comprising 0.1 to 5% by weight of at least one silane compound having a structure of Formula 9 as the adhesive silane additive: [Formula 9] (Wherein R is a methyl or ethyl group; X is a vinyl, allyl, glycidyloxy or methacryloxy group) The silicone resin composition for a semiconductor package according to claim 1, further comprising 5 to 100 ppm of a divinyltetramethyldisiloxane-platinum complex having the structure of Formula 10 as the addition-curing platinum catalyst: [Formula 10] The silicone resin composition for semiconductor package according to claim 1, comprising 50 to 60% by weight of the fused spherical silica.