JP7573244B2 - Encapsulating resin composition and semiconductor device - Google Patents

Description

The present disclosure relates to an encapsulating resin composition and a semiconductor device, and more particularly to an encapsulating resin composition for encapsulating electronic components such as semiconductor elements, and a semiconductor device including an encapsulant made from the encapsulating resin composition.

Patent Document 1 discloses a liquid epoxy resin composition for sealing that contains liquid bisphenol-type epoxy resin, silicone rubber fine particles, silicone-modified epoxy resin, aromatic amine curing agent, coupling agent, inorganic filler, and organic solvent. It is disclosed that this liquid epoxy resin composition for sealing can suppress warpage to a minimum even when applied to electronic component devices that require low warpage, and has excellent reliability such as strength, thermal shock resistance, and moisture resistance.

JP 2007-23272 A

The object of the present disclosure is to provide an encapsulating resin composition that is easy to fill between a substrate and a chip and is less likely to cause cracks in the encapsulating material, even when preparing an encapsulating material that seals between the substrate and a large chip, and a semiconductor device that includes an encapsulating material made of a cured product of this encapsulating resin composition.

The encapsulating resin composition according to one embodiment of the present disclosure contains an epoxy resin (A), phosphoric acid (B), and a phosphate polyester (C). The epoxy resin (A) contains a silicone resin (A1) having two or more epoxy groups in one molecule.

A semiconductor device according to one aspect of the present disclosure includes a substrate, a mounting component mounted on the substrate, and a sealant that seals a gap between the substrate and the mounting component. The sealant is made of a cured product of the sealing resin composition.

FIG. 1 is a schematic cross-sectional view showing a semiconductor device according to an embodiment of the present disclosure.

1. Overview The encapsulating resin composition according to the present embodiment contains an epoxy resin (A), a phosphoric acid (B), and a phosphate polyester (C). The epoxy resin (A) contains a silicone resin (A1) having two or more epoxy groups in one molecule.

Conventionally, by blending an inorganic filler such as silica in a resin composition for sealing, the heat resistance of the sealing material made from the resin composition has been improved and the coefficient of thermal expansion (CTE) has been reduced. However, if the proportion of the filler in the resin composition is too high, the filler tends to aggregate, and the viscosity of the resin composition increases excessively, decreasing the flowability, which may result in a decrease in moldability. If the moldability of the resin composition decreases when molding the resin composition, there is a problem that the resin composition cannot be sufficiently filled deep into the gap between the substrate and the semiconductor chip in a semiconductor device when sealing the gap with the resin composition.

In recent years, chips have also been made larger. As chips become larger, the size of the encapsulant also becomes larger, which tends to increase the stress on the encapsulant, and as a result, performance such as thermal shock resistance may not be fully achieved. This makes the encapsulant more susceptible to cracking and peeling. In addition, when encapsulants are made from compositions, there is a problem in that it becomes difficult to sufficiently fill the gap between the chip and a base material such as a substrate when the chip becomes larger.

In contrast, the encapsulating resin composition of the present embodiment can impart thermosetting properties to the encapsulating resin composition and can reduce the storage modulus of the encapsulating resin composition and the cured product of the encapsulating resin composition by containing the silicone resin (A1) in the epoxy resin (A). In addition, the CTE of the cured product produced from the encapsulating resin composition can be reduced. In addition, the encapsulating resin composition of the present embodiment can maintain a low viscosity and can have a thixotropic index close to 1, so that it can have good fluidity.

Furthermore, by containing phosphoric acid (B) and phosphate polyester (C), the encapsulating resin composition can improve the dispersibility of the components in the encapsulating resin composition. Therefore, even if the viscosity is easily increased by the silicone resin (A1), the encapsulating resin composition can maintain good fluidity because of the increased dispersibility. This makes it easier for the encapsulating resin composition to flow in the gap between the substrate and the mounting board, and therefore makes it easier to sufficiently fill the gap with the encapsulant.

As described above, the encapsulating resin composition of this embodiment can achieve good fluidity, and can achieve a low CTE and low elastic modulus of the cured product produced from the encapsulating resin composition. In particular, the cured product produced from the encapsulating resin composition of this embodiment can achieve not only a low CTE and low elastic modulus, but also an improvement in fracture toughness K1c, by containing silicone resin (A1), phosphoric acid (B), and phosphate polyester (C). In this disclosure, fracture toughness K1c is resistance to fracture when a force is applied to a material having a defect. The fracture toughness is measured by the method described in the examples below. And, with the encapsulating resin composition of this embodiment, it is possible to produce an encapsulating material that is less likely to crack due to its high fracture toughness. In particular, in this embodiment, it is possible to make it less likely to crack when the chip size of the semiconductor chip is increased due to the high functionality of the semiconductor device, and to improve the reliability of the semiconductor device.

In the present disclosure, larger chips means, for example, that the chip size of a semiconductor chip or the like in a mounting component is rectangular in plan view with a side length of 25 mm or more, or that the area in plan view is 625 ^mm2 or more. However, in this embodiment, the chip size is not limited to the above, and the composition according to this embodiment can be applied regardless of the chip size.

More specifically, the preferred properties of such an encapsulating resin composition can be achieved by appropriately adjusting the components of the composition described below.

As shown in FIG. 1, the encapsulating resin composition according to this embodiment can be suitably used as an encapsulating material 4 that seals between a substrate 2 and a mounting component 3 such as a semiconductor chip in a semiconductor device 1. In particular, the encapsulating resin composition can be suitably used as an underfill material. When the encapsulating resin composition is used as an underfill material and the encapsulating material 4 is produced from the encapsulating resin composition, the encapsulating material 4 is less susceptible to cracks.

2. Details Components that may be contained in the encapsulating resin composition will be described in detail.

[Epoxy resin (A)]
The encapsulating resin composition of the present embodiment contains an epoxy resin (A). The epoxy resin (A) is a thermosetting component. The epoxy resin (A) has at least one epoxy group in one molecule. In the present embodiment, the epoxy resin (A) contains a silicone resin (A1) having two or more epoxy groups in one molecule.

The viscosity of the epoxy resin (A) at 25°C is preferably 100 mPa·s or more and 20 Pa·s or less. The viscosity of the epoxy resin (A) can be measured, for example, using a B-type rotational viscometer at a rotation speed of 50 rpm.

[Silicone resin (A1)]
As described above, the encapsulating resin composition contains the silicone resin (A1). The silicone resin (A1) has two or more epoxy groups in one molecule.

A silicone resin is a compound having a siloxane bond in a molecule. In this embodiment, the silicone resin (A1) has at least one siloxane bond and two or more epoxy groups in one molecule. The silicone resin (A1) in the encapsulating resin composition of this embodiment has a siloxane skeleton, which can contribute to a decrease in CTE. In addition, since it has an epoxy group, it can impart thermosetting properties to the encapsulating resin composition.

It is preferable that the silicone resin (A1) has at least one epoxy group at the end of one molecule. In this case, since the silicone resin (A1) is not likely to cause aggregation, it is not likely to excessively increase the viscosity of the encapsulating resin composition, and therefore good fluidity can be ensured. Here, the end of one molecule refers to the position of the end of the linking chain that is bonded to the silicon atom in the siloxane bond in the molecule, which is the farthest from the silicon atom. For example, even if the silicone resin (A1) is branched, the end may be any of the ends of each branch. In the silicone resin (A1), if an epoxy group is present at the end of the molecule, the reactivity of the encapsulating resin composition is not likely to increase excessively, and the storage stability of the encapsulating resin composition can be maintained. Therefore, when the encapsulating resin composition is molded, moldability (processability) can be maintained, it is not likely to harden during molding, and it is easy to fill the gap between the substrate and the semiconductor chip.

It is preferable that the silicone resin (A1) is liquid at 25°C. In this case, the viscosity of the encapsulating resin composition is particularly easy to adjust to a suitable viscosity for molding. Also, in this case, even if the encapsulating resin composition does not contain a solvent, it is easy to prepare it to have a suitable viscosity. The viscosity of the silicone resin (A1) at 25°C is preferably, for example, 1000 mPa·s or less.

The content of silicone resin (A1) relative to the total amount of epoxy resin (A) is preferably 0.1% by mass or more and 15.0% by mass or less. In this case, it can contribute to lowering the viscosity of the encapsulating resin composition and improving the fracture toughness K1c. The content of silicone resin (A1) is more preferably 0.5% by mass or more and 12.0% by mass or less, and even more preferably 1.0% by mass or more and 10.0% by mass or less.

[Bisphenol-type epoxy resin (A2)]
The epoxy resin (A) preferably further contains a bisphenol-type epoxy resin (A2). That is, the encapsulating resin composition preferably further contains a bisphenol-type epoxy resin (A2). In this case, the encapsulating resin composition can be provided with thermosetting properties.

The bisphenol type epoxy resin (A2) contains at least one selected from the group consisting of, for example, bisphenol A type epoxy resin, bisphenol type epoxy resin, bisphenol S type epoxy resin, and derivatives of these resins. The bisphenol type epoxy resin (A2) preferably contains a bisphenol F type epoxy resin in particular. In this case, the encapsulating resin composition can be imparted with better thermosetting properties. The bisphenol F type epoxy resin is a compound in which two phenol skeletons are bonded via one ethylene chain. The bisphenol F type epoxy resin may have a substituent in the phenol skeleton.

The viscosity of the bisphenol type epoxy resin (A2) at 25°C is preferably, for example, 1000 mPa·s or more and 4000 mPa·s or less.

[Aromatic amino epoxy resin (A3)]
It is preferable that the epoxy resin (A) further contains an aromatic aminoepoxy resin (A3). That is, it is preferable that the encapsulating resin composition further contains an aromatic aminoepoxy resin (A3). In this case, it is possible to impart better thermosetting properties to the encapsulating resin composition while maintaining the storage stability of the encapsulating resin composition.

The aromatic amino epoxy resin (A3) preferably has an aromatic ring, an amino group bonded to the aromatic ring, and three or more epoxy groups in one molecule. In other words, the aromatic amino epoxy resin (A3) is preferably trifunctional or more.

It is more preferable that the aromatic amino epoxy resin (A3) has an aromatic ring, an amino group bonded to the aromatic ring, an epoxy group bonded to the amino group, and an epoxy group bonded to a position other than that of the amino group bonded to the aromatic ring. In other words, when the aromatic amino epoxy resin (A3) has three or more epoxy groups, it is preferable that at least one of them is bonded to an amino group bonded to the aromatic ring.

Specific examples of aromatic aminoepoxy resins (A3) include N,N-diglycidyl-p-glycidyloxyaniline. Note that aromatic aminoepoxy resins (A3) are not limited to the above compounds.

The viscosity of the aromatic aminoepoxy resin (A3) at 25°C is preferably 400 mPa·s or more and 800 mPa·s or less.

It is preferable that the epoxy resin (A) further contains at least one of a bisphenol type epoxy resin (A2) and an aromatic amino epoxy resin (A3). It is more preferable that the encapsulating resin composition contains both the above-mentioned bisphenol type epoxy resin (A2) and the aromatic amino epoxy resin (A3). In this case, it is easy to proceed with a moderate curing reaction of the components in the encapsulating resin composition, and therefore it is easy to seal the gap between the substrate and the semiconductor chip with the encapsulant made from the encapsulating resin composition. When the encapsulating resin composition contains the bisphenol type epoxy resin (A2) and the aromatic amino epoxy resin (A3), it is preferable that the mass ratio of the total amount of the bisphenol type epoxy resin (A2) and the aromatic amino epoxy resin (A3) to the epoxy resin (A) is 85% by mass or more and 95% by mass or less.

When the encapsulating resin composition contains a bisphenol type epoxy resin (A2) and an aromatic amino epoxy resin (A3), the total content of the bisphenol type epoxy resin (A2) and the aromatic amino epoxy resin (A3) relative to the total amount of the encapsulating resin composition is preferably 30% by mass or more and 50% by mass or less, more preferably 35% by mass or more and 45% by mass or less, and even more preferably 30% by mass or more and 40% by mass or less. If it is within this range, the fluidity of the encapsulating resin composition is more easily maintained and the gap between the substrate and the semiconductor chip can be filled well, so that the gap between the substrate and the semiconductor chip can be sufficiently sealed.

In addition, the components that may be contained in the epoxy resin (A) in the encapsulating resin composition are not limited to those described above, and may contain resins having epoxy groups other than those described above.

[Phosphoric acid (B)]
The encapsulating resin composition contains phosphoric acid (B). The phosphoric acid (B) has a structure represented by the following formula (1).

When the encapsulating resin composition contains phosphoric acid (B), it can promote the effect of improving the dispersibility in the encapsulating resin composition by the phosphoric acid polyester (C) described below. It is preferable that phosphoric acid (B) is mixed with phosphoric acid polyester (C) to prepare a mixture and then blended into the encapsulating resin composition.

[Phosphate polyester (C)]
The encapsulating resin composition contains a phosphate polyester (C). When the encapsulating resin composition contains the phosphate polyester (C), the dispersibility of the components in the encapsulating resin composition is easily increased. Therefore, even if the encapsulating resin composition contains a silicone resin (A1) that is a compound containing silicon, the viscosity of the encapsulating resin composition is unlikely to increase excessively, and good fluidity can be ensured. Furthermore, the effect of reducing the CTE of the cured product produced from the encapsulating resin composition is unlikely to be hindered. In addition, the encapsulating resin composition contains phosphoric acid (B) and the phosphate polyester (C), so that the dispersibility is unlikely to decrease even if the proportion of the inorganic filler (filler) is increased. Therefore, the proportion of the filler in the encapsulating resin composition can be easily increased, and it is easier to achieve a reduction in the CTE of the cured product produced from the encapsulating resin composition.

The phosphate polyester (C) may have a structure shown in the following formula (2).

In formula (2), R ₁ , R ₂ , and R ₃ are, for example, each independently a substituent selected from the group consisting of an alkyl group, an alkenyl group, and an alkynyl group. R ₁ , R ₂ , and R ₃ may each independently be a long chain or a branched chain. At least one of R ₁ , R ₂ , and R ₃ may be a hydrogen atom. That is, phosphoric acid polyester (C) is a compound in which at least two hydrogen atoms in formula (1) of phosphoric acid (B) are each independently substituted with R ₁ , R ₂ , and R ₃ .

The substituents R ₁ , R ₂ , and R ₃ may each contain a phosphorus atom, and for example, the phosphate polyester (C) may be a compound derived from polyphosphoric acid represented by the following formula (3). That is, the phosphate polyester (C) may have two or more phosphorus atoms in one molecule.

In formula (3), n is 2 or more. When the phosphate polyester (C) is derived from formula (3), at least two of the hydrogen atoms in formula (3) may be substituted with a group selected from the group consisting of an alkyl group, an alkenyl group, and an alkynyl group. The phosphate polyester (C) may also have a hydroxyl group at the end. When n=1, it corresponds to the phosphate (B) represented by formula (1).

The phosphate polyester (C) is not limited to the above, and may include, for example, a reaction product obtained by reacting an appropriate alkyl ether, polyalkylene glycol monoalkyl ether, etc. with a phosphate esterifying agent.

Specific examples of phosphate polyester (C) products include phosphate polyesters that may be included in the BYK-W series (e.g., BYK-W9010, etc.) and DISPERBYK series (e.g., DISPERBYK-111, etc.) manufactured by BYK-Chemie Japan Co., Ltd.

In the encapsulating resin composition, the mass proportion of the phosphate polyester (C) is preferably more than 0 mass% and less than 100 mass%, more preferably 0.01 mass% or more and 90 mass% or less, even more preferably 0.02 mass% or more and 50 mass% or less, and particularly preferably 0.05 mass% or more and less than 10 mass%.

When the encapsulating resin composition contains silica (E1), the total mass ratio of phosphoric acid (B) and phosphate polyester (C) to silica (E1) is preferably 0.05% by mass or more and 1.0% by mass or less. In this case, the CTE of the cured product of the encapsulating resin composition can be further reduced. The mass ratio of the phosphate polyester (C) is more preferably 0.1% by mass or more and 0.5% by mass or less, and even more preferably 0.2% by mass or more and 0.4% by mass or less. In this case, the encapsulating resin composition can be given better fluidity, which makes it easier to fill the gaps with the encapsulating resin composition.

In the encapsulating resin composition, the total mass ratio of phosphoric acid (B) and phosphate polyester (C) to silicone resin (A1) is preferably 30% by mass or more and 70% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less.

[Curing aid (D)]
The encapsulating resin composition preferably contains a curing aid (D). In this case, it can contribute to the storage stability of the encapsulating resin composition. In addition, in this case, when the encapsulating resin composition is cured, the speed of the curing reaction can be controlled. The curing aid (D) includes a curing accelerator. The curing aid (D) has a function of promoting the progress of the reaction of the curable components in the encapsulating resin composition. In this embodiment, the curing aid (D) can gently promote the progress of the curing reaction of the silicone resin (A1) in the encapsulating resin composition. In addition, when the encapsulating resin composition contains curable components such as the bisphenol type epoxy resin (A2) and the aromatic amino epoxy resin (A3), the curing of these components can also be promoted. In particular, in this embodiment, when the epoxy resin (A) in the encapsulating resin composition is cured, the curing aid (D) can suppress the curing reaction from proceeding excessively. That is, the curing aid (D) is unlikely to excessively increase the reactivity of the curing of the encapsulating resin composition, and the curing can proceed at a good curing speed. Therefore, even if the encapsulating resin composition begins to harden due to a rise in temperature during molding, etc., the hardening is unlikely to progress rapidly, so that the fluidity is unlikely to be lost during molding, and as a result, the encapsulating resin composition can be hardened after being sufficiently filled.

It is preferable that the curing aid (D) contains a chelate compound (D1). In this case, the metal atom in the chelate compound (D1) can coordinate with the oxygen atom in the epoxy resin (A), so that excessive thermosetting reaction of the epoxy resin (A) in the encapsulating resin composition can be suppressed. This can further improve the storage stability of the encapsulating resin composition. In addition, in this case, excessive increase in the viscosity of the encapsulating resin composition can also be suppressed. Therefore, the fluidity of the encapsulating resin composition can be better maintained.

The chelate compound (D1) contains at least one compound selected from the group consisting of, for example, aluminum acetylacetonate, titanium acetylacetonate, titanium tetraacetylacetonate, titanium acetoacetate, zirconium ethylacetoacetate, and zirconium tetraacetylacetonate. It is preferable that the chelate compound (D1) contains aluminum acetylacetonate.

When the curing aid (D) is contained, the mass ratio of the curing aid (D) to the epoxy resin (A) is preferably 0.01% by mass or more and 2.0% by mass or less, more preferably 0.03% by mass or more and 1.5% by mass or less, and even more preferably 0.1% by mass or more and 1.0% by mass or less. If it is within this range, the curing property of the epoxy resin (A) in the encapsulating resin composition can be improved, and even if the chip size is increased, the gap between the substrate and the semiconductor chip can be sufficiently sealed with the cured product of the encapsulating resin composition.

The content of the chelate compound (D1) relative to the curing aid (D) is preferably 20% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 90% by mass or less, and even more preferably 50% by mass or more and 70% by mass or less.

[Inorganic filler (E)]
The encapsulating resin composition preferably contains an inorganic filler (E). The inorganic filler (E) contributes to a decrease in the linear expansion coefficient of a cured product produced from the encapsulating resin composition. In the present embodiment, since the encapsulating resin composition contains phosphoric acid (B) and phosphoric acid polyester (C), even if the encapsulating resin composition contains an inorganic filler (E), the encapsulating resin composition can be encapsulated. Therefore, the viscosity of the encapsulating resin composition is not likely to increase excessively, the fluidity can be maintained, and the thixotropy is not likely to deteriorate. In the encapsulating resin composition, even if the content of the inorganic filler (E) is increased, the flowability is not easily deteriorated, and the linear expansion coefficient of the encapsulating resin composition can be reduced.

It is preferable that the inorganic filler (E) contains silica (E1), and it is also preferable that at least a part of the silica (E1) is surface-treated with a coupling agent. In this case, the silica (E1) can be easily compatible with the silicone resin (A1), which can further contribute to improving the dispersibility of the encapsulating resin composition. The coupling agent is, for example, a silane coupling agent. Examples of the silane coupling agent include compounds having at least one functional group selected from the group consisting of an epoxy group, an amino group, a (meth)acryloyl group, and a phenyl group. It is preferable that the silane coupling agent is a silane coupling agent having a phenyl group. That is, it is preferable that at least a part of the silica (E1) is surface-treated with a silane coupling agent having a phenyl group. In this case, the silica (E1) can be particularly easily compatible with the silicone resin (A1) in the encapsulating resin composition, which can further improve the dispersibility of the encapsulating resin composition.

When the inorganic filler (E) contains silica (E1), it is preferable that the silica (E1) contains a first silica filler (E11) and a second silica filler (E12) having an average particle size different from that of the first silica filler (E11). In this disclosure, the "average particle size" is the volume average diameter. The volume average diameter is calculated from the particle size distribution obtained by measurement using a laser diffraction/scattering method. The particle size distribution can be measured, for example, by a laser diffraction particle size distribution measuring device, and an example of the laser diffraction particle size distribution measuring device is the LA-960 series manufactured by Horiba, Ltd.

The average particle size of the first silica filler (E11) is preferably 0.1 μm or more and 1.5 μm or less, and in this case, the standard deviation in the particle size distribution of the first silica filler (E11) is preferably 0.01 or more and less than 1.0. The average particle size of the second silica filler (E12) is preferably 10% or more and 50% or less of the average particle size of the first silica filler (E11), and the standard deviation in the particle size distribution of the second silica filler (E12) is preferably 0.01 or more and less than 1.0. Here, the "standard deviation in the particle size distribution" in this disclosure is an index indicating the width or narrowness of the particle size distribution. The standard deviation in the particle size distribution can be used to determine whether the particle size of the particles is uniform or not. The standard deviation in the particle size distribution can be calculated as follows. As with the above average particle size (volume average diameter), the standard deviation can be calculated from the particle size data of each particle and the average particle size in the particle size distribution obtained by measuring using the laser diffraction/scattering method. When the silica particles in each of the first silica filler (E11) and the second silica filler (E12) of the silica (E1) in the encapsulating resin composition have a standard deviation in particle size distribution of 0.01 or more and less than 1.0, the viscosity of the encapsulating resin composition can be further reduced. This ensures the flowability of the encapsulating resin composition. Therefore, when the encapsulating resin composition is used to seal the gap between the substrate and the semiconductor element, it is possible to achieve better moldability.

The average particle size of the first silica filler (E11) is preferably 0.1 μm or more and 1.0 μm or less. The standard deviation in the particle size distribution of the first silica filler (E11) is preferably 0.01 or more and 0.6 or less, more preferably 0.02 or more and 0.40 or less, even more preferably 0.02 or more and 0.36 or less, and particularly preferably 0.05 or more and 0.36 or less. The average particle size of the second silica filler (E12) is not particularly limited as long as it satisfies the above, but the average particle size of the second silica filler (E12) can be, for example, 0.01 μm or more and 0.75 μm or less. The standard deviation in the particle size distribution of the second silica filler (E12) is preferably 0.01 or more and less than 0.10, more preferably 0.02 or more and 0.08 or less, even more preferably 0.03 or more and 0.08 or less, and particularly preferably 0.04 or more and 0.06 or less.

It is preferable that the first silica filler (E11) and the second silica filler (E12) are both wet silica. Wet silica is amorphous silica synthesized in a liquid. For example, wet silica can be produced by at least one method selected from the group consisting of a precipitation method and a sol-gel method. It is particularly preferable that the wet silica is produced by the sol-gel method. In this case, the average particle size of the wet silica particles can be kept relatively small, such as 0.1 μm or more and 1.5 μm or less, and the particle size distribution can be made less likely to vary. That is, in this case, the particle size of the first silica filler (E11) and the second silica filler (E12) can be easily made uniform. The sol-gel method is a synthesis method in which a solid substance is obtained from a sol state in which fine particles such as colloids are dispersed in a solution, via a gel state in which fluidity is lost, and an appropriate synthesis method may be adopted. In addition, the first silica filler (E11) of the present disclosure can be confirmed to be produced by the sol-gel method by cutting a suitable particle of the first silica filler (E11) and observing the cross section. Specifically, for example, the cured product of the sealing resin composition is cut, the cut surface is observed with an electron microscope, etc., and the particle size of silica on the cut surface is measured, so that it can be determined that it is produced by the sol-gel method. It can also be confirmed that the second silica filler (E12) and the third silica filler (E13) described later are produced by the sol-gel method in the same manner as the first silica filler (E11).

It is also preferable that the silica (E1) further contains a third silica filler (E13) whose average particle size is different from both the first silica filler (E11) and the second silica filler (E12). That is, it is also preferable that the sealing resin composition contains the first silica filler (E11), the second silica filler (E12), and the third silica filler (E13). When the silica (E1) contains the third silica filler (E13), the average particle size of the third silica filler (E13) is not particularly limited as long as it is smaller than the average particle size of the second silica filler (E12). The standard deviation in the particle size distribution of the third silica filler (E13) is preferably 0.01 or more and less than 0.10, more preferably 0.02 or more and 0.09 or less, even more preferably 0.03 or more and 0.08 or less, and particularly preferably 0.04 or more and 0.06 or less. When the encapsulating resin composition contains the third silica filler (E13), the encapsulating resin composition can have a particularly low fluidity, and can have good thixotropy even if the fluidity of the encapsulating resin composition is low. The mass ratio of the third silica filler (E13) is preferably 5% by mass or more and 40% by mass or less with respect to the total amount of silica (E1). If the mass ratio of the third silica filler (E13) with respect to the total amount of silica (E1) is 5% by mass or more, the thixotropy can be made better, and if it is 40% by mass or less, good fluidity can be maintained.

When the silica (E1) contains a third silica filler (E13), the third silica (E13) is also preferably a wet silica. In this case, the third silica filler (E13) is also preferably a wet silica produced by a sol-gel method. In this case, it is easy to adjust each of the first silica filler (E11), the second silica filler (E12), and the third silica filler (E13) to be silica particles with a uniform particle size.

The first silica filler (E11) may be surface-treated with a coupling agent. The surface treatment of the silica filler can be performed, for example, by reacting wet silica prepared by a sol-gel method with a coupling agent (e.g., a silane coupling agent). The second silica filler (E12) and the third silica filler (E13) may also be surface-treated with a coupling agent.

The mass ratio of the first silica filler (E11) to the second silica filler (E12) in the silica (E1) is preferably within the range of 60:40 to 98:2. When the silica (E1) further contains a third silica filler (E13), the mass ratio of the first silica filler (E11), the second silica filler (E12), and the third silica filler (E13) is preferably within the range of 60:30:10 to 90:8:2.

When the inorganic filler (E) is contained, the content of the inorganic filler (E) relative to the total amount of the encapsulating resin composition is preferably 50% by mass or more and 75% by mass or less. In this case, it is possible to further reduce the CTE of the encapsulating resin composition. In this embodiment, even if the proportion of the inorganic filler is relatively high, the fluidity of the encapsulating resin composition can be particularly well maintained. Therefore, it is possible to prevent the encapsulating resin composition from being left unfilled in the gaps. The content of the inorganic filler (E) is preferably 50% by mass or more and 70% by mass or less, and more preferably 55% by mass or more and 65% by mass or less.

The inorganic filler (E) may contain fillers other than silica as long as they do not impair the effects of the present disclosure.

[Other ingredients]
The encapsulating resin composition may contain components other than those described above, as long as the effects of the present disclosure are not impaired. For example, the encapsulating resin composition may contain a resin component other than those described above.

The encapsulating resin composition may contain appropriate additives. Examples of additives include curing agents, fluxes, viscosity modifiers, surface modifiers, silane coupling agents, defoamers, leveling agents, stress reducing agents, and pigments.

For example, it is preferable that the encapsulating resin composition contains a silane coupling agent. In this case, the compatibility between the silicone resin (A1) and the silane coupling agent in the encapsulating resin composition is improved, and the dispersibility of the encapsulating resin composition is easily improved. In addition, when the encapsulating resin composition contains silica (E1), the dispersibility of the encapsulating resin composition is easily improved. As the silane coupling agent, any suitable coupling agent can be used, but it may also be an epoxy silane coupling agent such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

It is preferable that the encapsulating resin composition does not contain organic solvents or contains 0.5 mass% or less of organic solvents.

The encapsulating resin composition can be obtained, for example, by blending the above components and adding appropriate additives as necessary. Specifically, the encapsulating resin composition can be prepared, for example, by the following method.

First, the components that can be included in the encapsulating resin composition described above are mixed together, either simultaneously or sequentially, to obtain a mixture. This mixture is stirred and mixed while being heated or cooled as necessary.

Next, additives are added to the mixture as necessary, and the mixture is stirred again while being heated or cooled as necessary until it is uniformly dispersed. This allows the encapsulating resin composition to be obtained. To stir the mixture, for example, a disperser, planetary mixer, ball mill, three-roll mill, and bead mill can be used in appropriate combination as necessary.

The viscosity of the encapsulating resin composition at 25°C is preferably less than 35 Pa·s. In this case, when molding the encapsulating resin composition, the coating workability by jet dispensing and the discharge stability can be improved. In addition, in this case, good filling properties under mounting components such as semiconductor chips can be achieved. The viscosity of the encapsulating resin composition at 25°C is more preferably 25 Pa·s or less, and even more preferably 20 Pa·s or less. The lower limit of the viscosity of the encapsulating resin composition at 25°C is not particularly limited, but is, for example, 2 Pa·s or more.

The encapsulating resin composition can be cured, for example, by heating. The heating conditions, such as the heating temperature, heating time, and maximum heating temperature, can be adjusted appropriately depending on the type of curable component (A) and the type of curing agent, etc.

The glass transition temperature Tg of the cured product of the encapsulating resin composition is preferably 80°C or higher. It is also preferable that the glass transition temperature Tg is less than 180°C. If the glass transition temperature Tg is 80°C or higher, the cured product of the encapsulating resin composition can have heat resistance. It is more preferable that the glass transition temperature Tg is 90°C or higher and 170°C or lower. The glass transition temperature can be measured, for example, by TMA (Thermomechanical Analysis).

The coefficient of linear expansion (CTE) of the cured product of the encapsulating resin composition at or below the glass transition temperature Tg is preferably 20 ppm/°C to 40 ppm/°C, more preferably 30 ppm/°C or less, and even more preferably 25 ppm/°C or less. In this case, the encapsulating resin composition and the cured product of the encapsulating resin composition are less likely to warp due to heating. Therefore, the cured product of the encapsulating resin composition is less likely to crack. The coefficient of linear expansion of the cured product of the encapsulating resin composition is obtained by calculating the slope of the tangent based on the dimensional change at a temperature below Tg and the dimensional change at any temperature above Tg from the Tg obtained by measurement using TMA.

The storage modulus of the cured product of the encapsulating resin composition at 25°C is preferably 6.0 GPa or more and 12.0 GPa or less, and more preferably 6.5 GPa or more and 10 GPa or less. In this case, the dimensional change due to heating of the cured product of the encapsulating resin composition is less likely to occur. This makes it possible to make the cured product of the encapsulating resin composition less likely to crack. The storage modulus of the cured product of the encapsulating resin composition can be obtained by measuring with a DMA device in accordance with JIS K6911.

The fracture toughness K1c of the cured product of the encapsulating resin composition at 25°C is preferably 2.0 MPa·m ^1/2 or more. In this case, the cured product of the encapsulating resin composition is further prevented from cracking. This improves the reliability of the semiconductor device equipped with the encapsulant made of the cured product of the encapsulating resin composition. The fracture toughness K1c of the cured product is more preferably 2.5 MPa·m ^1/2 or more, and even more preferably 3.0 MPa·m ^1/2 or more. The fracture toughness K1c can be measured in accordance with JIS R1607. Specifically, it can be measured by the method described in the examples below.

As already mentioned, the encapsulating resin composition of this embodiment can be suitably used as an underfill material. The encapsulating resin composition can be particularly suitably used as a post-supply underfill material in flip chip mounting.

Figure 1 shows an example of a semiconductor device 1 according to this embodiment. The semiconductor device 1 comprises a substrate 2 supporting a mounted component 3 such as a semiconductor chip, the mounted component 3 mounted face-down on the substrate 2, and a sealant 4 sealing the gap between the substrate 2 and the mounted component 3. The sealant 4 is made of a cured product of the liquid sealing resin composition described above.

The semiconductor device 1 and its manufacturing method will be described in detail.

The semiconductor device 1 includes a substrate 2 having conductor wiring 21, a mounting component 3 such as a semiconductor chip having bump electrodes 33 and mounted on the substrate 2 by bonding the bump electrodes 33 to the conductor wiring, and an encapsulant 4 covering the bump electrodes 33. The encapsulant 4 is a cured product of the encapsulating resin composition described above.

The substrate 2 is, for example, a motherboard, a package substrate, or an interposer substrate. For example, the substrate 2 includes an insulating substrate made of glass epoxy, polyimide, polyester, ceramic, or the like, and conductor wiring 21 made of a conductor such as copper formed on the surface of the insulating substrate. The conductor wiring 21 includes, for example, an electrode pad.

The mounted component 3 is, for example, a semiconductor chip. The semiconductor chip is, for example, a flip-chip type chip such as a BGA (ball grid array), an LGA (land grid array), or a CSP (chip size package). The semiconductor chip may be a PoP (package on package) type chip.

The mounting component 3 may include a plurality of bump electrodes 33. The bump electrodes 33 include solder. For example, as shown in FIG. 1, the bump electrodes 33 include a pillar 31 and a solder bump 32 provided at the tip of the pillar 31. The solder bump 32 is made of solder, and therefore the bump electrodes 33 include solder. The pillar 31 is made of copper, for example.

The melting point of the solder (e.g., the solder in the solder bump 32) of the bump electrode 33 is not particularly limited, but may be a temperature at which it can melt at or below the mounting temperature (e.g., 220 to 260°C) when mounting a mounting component 3 such as a semiconductor chip. The composition of the solder is not particularly limited and may be an appropriate composition, for example, Sn-Ag solder and Sn-Ag-Cu solder. The structure of the bump electrode 33 with solder is not limited to the above, and for example, the bump electrode 33 may have only a spherical solder bump 32 (solder ball). In other words, the bump electrode 33 does not need to have a pillar.

In the semiconductor device 1 shown in Figure 1, the sealing material 4 fills the entire gap between the substrate 2 and the mounted component 3. As a result, the sealing material 4 covers the entire bump electrode 33 and also covers the joint between the bump electrode 33 and the conductor wiring 21. In other words, this sealing material 4 is what is known as an underfill.

An example of a method for manufacturing the semiconductor device 1 will be described below, but the method for manufacturing the semiconductor device 1 is not limited to the method described below, and it is sufficient that the gap between the substrate 2 and the mounted component 3 in the semiconductor device 1 can be covered and sealed with the sealing resin composition described above.

First, a substrate 2 having conductor wiring 21 and a mounting component 3 having a bump electrode 33 are prepared, the mounting component 3 is placed on the substrate 2, and the bump electrode 33 is placed on the conductor wiring 21.

Next, the encapsulating resin composition is placed so as to cover the bump electrode 33, and the encapsulating resin composition and the bump electrode 33 are subjected to a heat treatment to harden the encapsulating resin composition to produce the encapsulant 4, and electrically connect the bump electrode 33 and the conductor wiring 21. Here, placing the encapsulating resin composition is not limited to placing a solid encapsulating resin composition on the encapsulated object (such as the bump electrode 33), but also includes applying a liquid encapsulating resin composition to the encapsulated object, and injecting the liquid encapsulating resin composition into the gap between the encapsulated objects to cover the encapsulated objects.

The above order does not have to be as described above. For example, the mounting component 3 may be disposed on the substrate 2, the bump electrode 33 may be disposed on the conductor wiring 21, and then the encapsulating resin composition may be disposed so as to cover the bump electrode 33. Conversely, the encapsulating resin composition may be disposed so as to cover the bump electrode 33, and then the mounting component 3 may be disposed on the substrate 2, and the bump electrode 33 may be disposed on the conductor wiring 21. Furthermore, as long as the encapsulating resin composition can be disposed so as to cover the bump electrode 33 during the manufacturing process, the encapsulating resin composition may be disposed at any time and in any position on the mounting component 3 and substrate 2.

Specifically, when preparing the encapsulant 4 shown in FIG. 1, for example, first, an encapsulating resin composition is placed on the substrate 2, and then the mounting component 3 is placed on the substrate 2 so that the encapsulating resin composition is between the substrate 2 and the mounting component 3 and the bump electrode 33 is placed on the conductor wiring 21. This causes the encapsulating resin composition to be placed so as to cover the bump electrode 33. Alternatively, first, the mounting component 3 is placed on the substrate 2 so that the bump electrode 33 is placed on the conductor wiring 21, and then the encapsulating resin composition is supplied between the substrate 2 and the mounting component 3, so that the encapsulating resin composition is placed between the substrate 2 and the mounting component 3 and the encapsulating resin composition is placed so as to cover the bump electrode 33.

When producing the encapsulant 4 shown in Figure 1, for example, first, an encapsulating resin composition is placed on the mounted component 3 so as to cover the bump electrode 33. Next, the mounted component 3 is placed on the substrate 2 so that the encapsulating resin composition is interposed between the substrate 2 and the mounted component 3, and the bump electrode 33 is placed on the conductor wiring 21. In this way, the encapsulating resin composition is placed so as to cover the bump electrode 33.

When placing the encapsulating resin composition on the substrate 2 or on the mounted component 3, the encapsulating resin composition is placed by, for example, a method using a dispenser, a screen printing method, an inkjet method, or a dipping method.

The heat treatment of the encapsulating resin composition and the bump electrode 33 is performed using a heating furnace such as a reflow furnace. Note that the heat treatment may be performed by an appropriate method using equipment other than a reflow furnace. When the encapsulating resin composition and the bump electrode 33 are subjected to the heat treatment, the solder in the bump electrode 33 melts, electrically connecting the bump electrode 33 and the conductor wiring 21, and the encapsulating resin composition hardens to produce the encapsulating material 4. This results in the semiconductor device 1. The conditions of the heat treatment may be appropriately set according to the composition of the encapsulating resin composition. In the heat treatment, the maximum heating temperature is preferably, for example, 220°C or higher and 260°C or lower. Note that, although an example of the heat treatment has been described above, the heat treatment is not limited to the above, and the maximum heating temperature may also be appropriately set according to the composition of the encapsulating resin composition.

Specific examples of the present disclosure are presented below. However, the present disclosure is not limited to the examples.

1. Preparation of resin composition [Examples 1 to 5 and Comparative Examples 1 to 5]
The components shown in Table 1 below were charged into a mixer in the mixing ratios (parts by mass) shown in Table 1, stirred and mixed, and uniformly dispersed using a three-roll mill to obtain a resin composition. Details of the components shown in Table 1 are as follows.
(Epoxy resin)
Epoxy-modified silicone resin 1: Momentive Performance Materials Japan, LLC, product name TSL9906, silicone resin with epoxy modification at both ends. Epoxy-modified silicone resin 2: ADEKA Corporation, product name EP-3400L, silicone resin with epoxy modification at both ends.
Bisphenol type epoxy resin: bisphenol F type epoxy resin (manufactured by Tohto Kasei Co., Ltd., product name YDF8170. Epoxy equivalent 175 eq./g).
Aromatic amino epoxy resin: jRR Corporation product name 636.
(Mixture of phosphoric acid and polyester phosphate)
Mixture of phosphoric acid and phosphate polyester: BYK Japan Co., Ltd., product name BYK-W 9010 (composition: phosphate polyester content 90% by weight or more and less than 100% by weight, phosphoric acid content 1% by weight or more and less than 10% by weight).
(Hardening agent)
Amine curing agent: Product name: Kayabard AA, manufactured by Nippon Kayaku Co., Ltd. Amine equivalent: 65 eq./g.
(Curing aid)
Chelate compound 1: Product name Aluminum Chelate A (W) manufactured by Kawaken Fine Chemical Co., Ltd. Metal chelate hardening assistant. Aluminum trisacetylacetonate.
Chelate compound 2: Matsumoto Fine Chemicals Co., Ltd. Product name: TC-100. Titanium trisacetylacetonate.
(Inorganic filler)
Silica 1: Silica prepared by a sol-gel method and surface-treated with a silane coupling agent having a phenyl group (average particle size 1.0 μm. Standard deviation in particle size distribution is 0.04 to 0.5).
Silica 2: Silica prepared by a sol-gel method and surface-treated with a silane coupling agent having a phenyl group (average particle size: 0.3 μm. Standard deviation in particle size distribution: 0.04 to 0.5).
Silica 3: Silica prepared by a sol-gel method and surface-treated with a silane coupling agent having a phenyl group (average particle size: 0.1 μm. Standard deviation in particle size distribution: 0.04 to 0.5).
Silica 4: Silica prepared by the sol-gel method and surface-treated with phenylsilane (average particle size: 50 nm, standard deviation in particle size distribution: 0.04 to 0.5).
Silica 5: Silica produced by the sol-gel method and surface-treated with phenylsilane (average particle size: 10 nm, standard deviation in particle size distribution: 0.04 to 0.5).
(Additives)
Coupling agent: epoxy silane (silane coupling agent. Product name KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.).
Colorant: Carbon black (product name MA100, manufactured by jER Co., Ltd.).

2. Evaluation 2.1. Viscosity The viscosity of the resin composition prepared in 1 above was measured using a BM type viscometer (Model TVB-10, manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25°C, rotor No. 6, and a rotation speed of 5 rpm. Based on the obtained measurement results, the viscosity was evaluated according to the following criteria.
A: Viscosity is less than 25 Pa·s.
B: Viscosity is 25 Pa·s or more and 35 Pa·s or less.
C: Viscosity is 35 Pa or more.

2.2. Thixotropic Index The viscosity at 25°C was measured in the same manner as in 2.1 above. The rotation speed of 5 rpm was then changed to about 1/10 of the original rotation speed of 5 rpm, and the viscosity was measured. The viscosity change rate (viscosity at low speed/viscosity at high speed) was calculated from the viscosity before the rotation speed was changed (at low speed) and the viscosity after the rotation speed was changed (at high speed), and this was taken as the thixotropic index (TI). Based on the obtained thixotropic index, the following criteria were used for evaluation.
A: TI is 0.7 or more and less than 1.5.
B: TI is 1.5 or more and less than 2.5.
C: TI is 2.5 or more.

2.3. Fluidity Two flat glass plates were placed on a heatable stage with a gap of 10 μm between them, and the temperature of the stage was set to 90° C. to heat the two glass plates. After the temperature of the glass plates reached 90° C., the resin composition prepared in 1. above was injected into the 10 μm gap and allowed to flow through the gap by utilizing capillary action. The time it took for the resin composition to travel a distance of 30 mm from the start of injection was measured. Based on the results obtained by the measurement, the evaluation was performed according to the following criteria.
A: The time required to advance 30 mm is less than 300 seconds.
B: The time required to advance 30 mm is 300 seconds or more and less than 500 seconds.
C: The time required to advance 30 mm is 500 seconds or more.

2.4. Glass transition temperature (DMA test)
The resin composition prepared in 1 above was applied onto a substrate, heated at 100° C. for 2 hours, and then heated at a further elevated temperature of 150° C. for 2 hours to cure the resin composition, thereby obtaining a cured product of the resin composition.

The cured product was then measured using a dynamic mechanical analysis (DMA) device (Model DMA7100, manufactured by Hitachi High-Tech Science Corporation) at a heating rate of 5°C/min from room temperature (-60°C) to 280°C, from which the glass transition temperature of the cured product was obtained. The obtained glass transition temperature values (°C) are shown in Table 1.

2.5. Linear expansion coefficient (TMA test)
A cured product of the resin composition prepared under the same conditions as in 2.4 above was heated from -60°C to 280°C using a thermomechanical analyzer (TMA) (Model TMA7000, manufactured by Hitachi High-Tech Science Corporation) under conditions of a load of 1 g and a heating rate of 5°C/min, and the dimensional change was measured. From the results obtained, the linear expansion coefficient was calculated and evaluated according to the following criteria.
A: Less than 35 ppm/°C.
C: 35 ppm/° C. or more.

2.6. Elastic modulus (storage modulus)
The elastic modulus at each temperature was measured using a DMA device under the same conditions as in 2.4 for the cured resin composition prepared under the same conditions as in 2.4. From the results obtained, the storage elastic modulus was calculated and evaluated according to the following criteria.
A: 6.5 GPa or more and less than 12.0 GPa.
C: 12.0 GPa or more.

2.7. Fracture toughness (K1c test)
A test specimen (length L: 50 mm, width W: 10 mm, thickness B: 5 mm) for test measurement was prepared from the cured product of the resin composition prepared under the same conditions as in 2.4 above, and a pre-crack with a crack length a: 4 mm was made in the test specimen. In accordance with JIS R1607 (room temperature fracture toughness test method for fine ceramics), pressure was applied to the test specimen at a rate of 10 mm/min to measure the test force until fracture. From the obtained measurement results, the K1c value was calculated based on the following formulas (1) and (2), and the obtained values are shown in Table 1. The fracture toughness K1c can be evaluated as being more resistant to cracks as the value increases.

In the above formulas (1) and (2), Pα: maximum load [kgf] until the test specimen breaks, S: distance between the three-point bending supports [mm], B: thickness of the test specimen [mm], W: width of the test specimen [mm], and a: length of the pre-crack [mm].

Reference Signs List 1 Semiconductor device 2 Substrate 3 Mounted component 4 Sealing material

Claims (7)

An epoxy resin (A),
Contains phosphoric acid (B) and phosphoric acid polyester (C),
The epoxy resin (A) contains a silicone resin (A1) having two or more epoxy groups in one molecule ,
The epoxy resin (A) further contains one or both of a bisphenol F type epoxy resin (A2) and an aromatic amino epoxy resin (A3).
An encapsulating resin composition. An epoxy resin (A),
Phosphoric acid (B) and
A phosphate polyester (C),
The epoxy resin (A) contains a silicone resin (A1) having two or more epoxy groups in one molecule,
Further containing a curing aid (D),
The curing aid (D) contains a chelate compound (D1).
An encapsulating resin composition. Further containing a curing aid (D),
The curing aid (D) contains a chelate compound (D1).
The encapsulating resin composition according to claim 1 . Further containing a mechanical filler (E),
The encapsulating resin composition according to claim 1 . The inorganic filler (E) contains silica (E1),
At least a part of the silica (E1) is surface-treated with a coupling agent.
The encapsulating resin composition according to claim 4 . It is an underfill material.
The encapsulating resin composition according to claim 1 . A substrate;
A mounting component to be mounted on the base material;
a sealant that seals a gap between the base material and the mounted component,
The encapsulant is made of a cured product of the encapsulating resin composition according to any one of claims 1 to 6.
Semiconductor device.

Images