JP2773955B2 - Semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable semiconductor device.

[Conventional technology]

Semiconductor elements such as transistors, ICs, and LSIs are usually sealed with a ceramic package or a plastic package to form a semiconductor device. The above-mentioned ceramic package has high heat resistance and excellent penetration resistance, so it is strong against temperature and humidity.
Moreover, since the hollow package has high mechanical strength, highly reliable sealing is possible. However, since the constituent materials are relatively valuable and have a disadvantage of being inferior in mass productivity, resin sealing using the plastic package has recently become mainstream. For this type of resin sealing,
Conventionally, epoxy resin compositions have been used and have achieved good results. However, due to technological innovation in the field of semiconductors, the degree of integration has been increased, the element size has been increased, and the wiring has become finer, and the packages have tended to become smaller and thinner. Therefore, further improvement in reliability (internal stress of the obtained semiconductor device, humidity resistance, shock resistance, heat resistance, and the like) has been demanded.
In particular, in recent years, the element (chip) size has been increasing in size, and there has been a demand for better performance in a thermal cycle test (TCT test), which is an accelerated test for evaluating the performance of a semiconductor sealing resin. . In addition, surface mounting has become a mainstream semiconductor device mounting method. For this reason, even if a semiconductor package is absorbed in moisture and then immersed in a solder bath, it is required that the package not crack or swell. I have. In order to respond to these problems, the sealing resin has been modified with rubber to reduce thermal stress for the purpose of improving the properties expressed in the TCT test, and the sealing resin has also been improved for the purpose of improving crack resistance during solder immersion. Improving the adhesion between the lead frame and the lead frame has been studied, but the effect is not yet sufficient.

[Problems to be solved by the invention]

As described above, although various improvements have been made, the effect of improving the TCT test of the epoxy resin composition for sealing and the effect of improving crack resistance during solder immersion are still insufficient. For this reason, there is a strong demand for the development of a technology capable of actually improving both of the above characteristics so as to be able to cope with an increase in the element size and surface mounting due to the above-mentioned technological innovation.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a semiconductor device in which the improvement of each characteristic represented by the TCT test and the improvement of crack resistance during solder immersion are actually realized.

[Means for solving the problem]

In order to achieve the above object, the semiconductor device of the present invention has a configuration in which a semiconductor element is sealed with an epoxy resin composition containing the following components (A) to (C).

(A) Epoxy resin.

(B) a curing agent.

(C) Average particle diameter of surface coated with spherical silica (X) having an average particle diameter of 20 to 70 μm and aminosilane coupling agent
An inorganic filler comprising crushed silica (Y) having a particle size of 0.1 to 10 μm, wherein the mixing ratio of X and Y based on the weight X / Y
Inorganic fillers set to be 9/1 to 1/1.

[Action]

That is, the present inventors have conducted a series of studies in order to actually improve the respective characteristics represented by the TCT test and the crack resistance during solder immersion. As a result, it was found that the inorganic filler has a large effect on the above properties, and further studies have shown that, when the above-mentioned component (C) is used as the inorganic filler, the properties shown in the TCT test and the solder immersion time The present inventors have found that the cracking resistance of P.I.

The epoxy resin composition used in the present invention is obtained by using an epoxy resin (A component), a curing agent (B component), and an inorganic filler (C component) having a special compounding ratio. , In the form of powder or tablet.

The epoxy resin (A component) is not particularly limited, and various epoxy resins conventionally used as sealing resins for semiconductor devices, such as novolak type, cresol novolak type, phenol novolak type, and bisphenol A type. Resins. Among these resins, the melting point is higher than room temperature, and the use of a resin which exhibits a solid state or a high-viscosity solution at room temperature gives a good result. As the novolak type epoxy resin, those having an epoxy equivalent of 160 to 250 and a softening point of 50 to 130 ° C are usually used.As the cresol novolak type epoxy resin, those having an epoxy equivalent of 180 to 210 and a softening point of 60 to 110 ° C are used. Is generally used.

As the curing agent (component B) used together with the epoxy resin (component A), phenol novolak, cresol novolak, or the like is suitably used. These novolak resins preferably have a softening point of 50 to 110 ° C. and a hydroxyl equivalent of 70 to 150. Particularly, the use of cresol novolak among the above novolak resins gives good results.

The mixing ratio of the epoxy resin (component A) and the curing agent (component B) is preferably such that the hydroxyl group in the curing agent is 0.8 to 1.2 equivalents per equivalent of epoxy group of the epoxy resin.

The epoxy resin (A component) and the curing agent (B component)
The special inorganic filler (component C) used with
Spherical silica having an average particle size of 20 to 70 μm and an average particle size of 0.1
Consists of a mixture with 1010 μm crushed silica. In addition, of the two types of silica powder, the surface of the crushed silica is coated with an aminosilane coupling agent.

In general, the fracture toughness value and the bending strength are used as a TCT test of an epoxy resin composition or a physical property index of solder cracking, and the fracture toughness value indicates the toughness to fracture of a brittle material having a crack, Flexural strength indicates the likelihood of cracking. The present inventors have conceived that the inorganic filler has a large effect on the TCT test and the solder cracking property, and examined the influence of the inorganic filler on the above-mentioned physical property index mainly on the particle size of the inorganic filler. as a result,
It was found that the larger the grain size, the higher the fracture toughness value, and the smaller the grain size, the higher the bending strength. In particular, in the case of crushed silica among the inorganic fillers, in the case of particles having a large particle diameter, the bending strength is reduced due to the destruction of the particles themselves. For this reason, the present inventors used spherical silica having a large particle size and crushed silica having a small particle size in order to improve both the fracture toughness value and the bending strength, and further improved the adhesive strength with the epoxy resin to increase the bending strength. In order to improve the performance, further studies have been made under the idea that it is effective to coat the surface of crushed silica having a small particle size with an aminosilane coupling agent. As a result, by performing the above, it is possible to actually suppress the occurrence of cracks during the TCT test and solder mounting, and even if a small crack occurs in the package, the silica stops the crack from progressing and prevents its expansion. It will be gained.

Further, the mixing ratio of the spherical silica (X) and the crushed silica (Y) whose surface is coated with an aminosilane coupling agent is set within a range of X: Y = 9: 1 to 1: 1 by weight. There is a need. The amount of the aminosilane coupling agent used is preferably set in the range of 0.1 to 2% by weight (hereinafter abbreviated as "%") based on the crushed silica.

The content of the special inorganic filler (component C) is preferably set to 50% or more of the entire epoxy resin composition. More preferably 70% or more, particularly preferably
80% or more. That is, the content of the inorganic filler is 50
%, The effect of improving crack resistance during solder immersion is greatly reduced.

The epoxy resin composition used in the present invention may further contain a curing accelerator, if necessary, in addition to the components A to C.
Coupling agents such as flame retardants, pigments and silane coupling agents can be used as appropriate.

Examples of the curing accelerator include conventionally known tertiary amines, quaternary ammonium salts, imidazoles, boron compounds and the like, and they are used alone or in combination.

Examples of the flame retardant include antimony trioxide and phosphorus compounds.

The epoxy resin composition used in the present invention can be produced, for example, as follows. That is, first, an aminosilane coupling agent and crushed silica having a specific particle size are mixed and stirred to coat the crushed silica surface. Next, the surface-treated crushed silica and spherical silica (component C), epoxy resin (component A), curing agent (component B), and if necessary, a curing accelerator, a flame retardant, a pigment, a coupling, and the like. The agents are mixed in a predetermined ratio. Next, the mixture is placed in a kneading machine such as a mixing roll machine, kneaded in a heated state, melt-mixed, cooled to room temperature, pulverized by known means, and tableted as necessary. The target epoxy resin composition can be obtained by the step (1).

The sealing of the semiconductor element using such an epoxy resin composition is not particularly limited, and can be performed by a known molding method such as ordinary transfer molding.

The semiconductor device obtained in this manner is characterized by the action of spherical silica having a large average particle size contained in the epoxy resin composition and crushed silica (C component) having a small average particle size surface-treated with an aminosilane coupling agent. The characteristics of the sealing resin are improved, and no package cracks or the like occur during solder mounting.

〔The invention's effect〕

As described above, according to the semiconductor device of the present invention, of the two types of silica having different particle sizes and shapes (spherical silica and crushed silica), crushed silica is mixed at a predetermined ratio which is surface-treated with an aminosilane coupling agent. Sealed using a special epoxy resin composition containing an inorganic filler (component C), which improves the properties expressed in the TCT test (eg, heat resistance, impact resistance, etc.). Longer life. Also, no package crack occurs even under severe conditions such as solder mounting. In particular, the high reliability described above can be obtained in a large semiconductor device having 8 pins or more, particularly 16 pins or more, or a chip having a long side of 4 mm or more by sealing with the special epoxy resin composition. This is a major feature.

 Next, examples will be described together with comparative examples.

[Examples 1 to 7, Comparative Examples 1 and 2] According to the following Table 1, aminosilane coupling agents were added to the crushed silica at the ratios shown in the same table, and the crushed silica was surface-treated by mixing and stirring. . Next, the surface-treated crushed silica and the remaining raw materials shown in the same table were blended in the ratio shown in the same table, and the mixture was mixed with a mixing roll machine (roll temperature of 10).
(0 ° C.) for 3 minutes, followed by cooling and solidification, followed by pulverization to obtain the desired finely powdered epoxy resin composition.

The semiconductor element is subjected to transfer molding (conditions: 175 ° C. × 2 minutes, 175 ° C. × 5 hours post-curing) using the fine powdered epoxy resin composition obtained by the above Examples and Comparative Examples. A semiconductor device was obtained. The semiconductor device thus obtained was subjected to a TCT test at −50 ° C./5 minutes to 150 ° C./5 minutes, left in a constant temperature bath of 85 ° C. × 85% RH to absorb moisture, and heated at a temperature of 260 ° C. for 10 seconds. A test for immersion in a solder bath was performed, and the number of cracks generated was measured. In addition, a fracture toughness test was performed based on ASTME 399-81 to determine a fracture toughness value. The bending strength was also measured. The results are shown in Table 2.

From the results in Table 2, it can be seen that the example product has high bending strength,
Excellent test and crack resistance test results during solder immersion. From this, it can be seen that the example product has significantly improved reliability as compared with the comparative product.

Continuation of front page (56) References JP-A-2-218736 (JP, A) JP-A-62-212420 (JP, A) JP-A-63-156345 (JP, A) JP-A-2-124923 (JP) , A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 23/29 C08L 63/00

Claims (2)

(57) [Claims] 1. A semiconductor device comprising a semiconductor element encapsulated with an epoxy resin composition containing the following components (A) to (C). (A) Epoxy resin. (B) a curing agent. (C) Average particle diameter of surface coated with spherical silica (X) having an average particle diameter of 20 to 70 μm and aminosilane coupling agent
An inorganic filler comprising crushed silica (Y) having a particle size of 0.1 to 10 μm, wherein the mixing ratio of X and Y based on the weight X / Y
Inorganic fillers set to be 9/1 to 1/1. 2. An epoxy resin composition for semiconductor encapsulation comprising the following components (A) to (C). (A) Epoxy resin. (B) a curing agent. (C) Average particle diameter of surface coated with spherical silica (X) having an average particle diameter of 20 to 70 μm and aminosilane coupling agent
An inorganic filler comprising crushed silica (Y) having a particle size of 0.1 to 10 μm, wherein the mixing ratio of X and Y based on the weight X / Y
Inorganic fillers set to be 9/1 to 1/1.