Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
  • H01L23/29—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the material, e.g. carbon
  • H01L23/293—Organic, e.g. plastic
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
  • C08L61/04—Condensation polymers of aldehydes or ketones with phenols only
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
  • C08L2666/14—Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
  • C08L2666/22—Macromolecular compounds not provided for in C08L2666/16 - C08L2666/20
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/0001—Technical content checked by a classifier
  • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/10—Details of semiconductor or other solid state devices to be connected
  • H01L2924/11—Device type
  • H01L2924/12—Passive devices, e.g. 2 terminal devices
  • H01L2924/1204—Optical Diode
  • H01L2924/12044—OLED

Definitions

• the present invention relates to an epoxy resin composition for encapsulating of semiconductors which is suitable for the so-called area mounting type semiconductor devices formed by mounting semiconductor elements on one side of a printed circuit board or a metallic lead frame and encapsulating with a resin substantially only the side on which the semiconductor elements are mounted, and to a semiconductor device manufactured using the resin composi- tion.
• the structure of the area mounting type semiconductor devices is such that semicon- ductor elements are mounted on one side of rigid circuit boards such as BT resin/copper foil circuit board
• solder balls are arranged in plane on the other side of the boards for bonding to a circuit board on which a semiconductor device is mounted.
• structures using metallic substrates such as lead frames have also been developed in addition to the above organic substrates .
• the structure of these area mounting type semiconductor devices has the form of one side encapsulating, that is, only the side of the board on which semiconductor elements are mounted is encapsulated with an epoxy resin composition and the side on which solder balls are formed is not encapsulated.
• an encapsulating resin layer of about several ten ju s is sometimes present also on the solder ball-formed side, while an encapsulating resin layer of about several hundred ms to several millimeters is formed on the semiconductor element-mounted side, and, as a result, this is substantially one side encapsulating.
• warping is apt to occur just after molding because of differences in thermal expansion • heat shrinkage between the organic substrate or the metal substrate and the cured product of the epoxy resin composition or because of cure shrinkage at the time of molding and curing of the epoxy resin composi- tion. Furthermore, when these semiconductor devices are bonded onto circuit boards with solder, this is conducted through a heating step at 200°C or higher, during which warping of the semiconductor devices occurs and many solder balls are not in flat state and are apart from the circuit boards to cause deterioration in reliability of electrical bonding.
• Tg such as BT resin and polyimide resin
• BT resin and polyimide resin are widely used for organic substrates, and these have a Tg higher than about 170°C which is the molding temperature of an epoxy resin composition. Therefore, during the cooling step of from the molding temperature to room temperature, shrinkage occurs only in the area of ⁇ l of the organic substrate. Accordingly, it is considered that if the cured product of epoxy resin composition also has a high Tg and the same ⁇ l as that of the organic substrate and, besides, is zero in the cure shrinkage, the warping is nearly zero.
• a method of raising the Tg by combination of a polyfunctional epoxy resin and a polyfunctional phenolic resin and meeting the ⁇ l by adjusting the amount of inorganic filler to be added has been already proposed a method of raising the Tg by combination of a polyfunctional epoxy resin and a polyfunctional phenolic resin and meeting the ⁇ l by adjusting the amount of inorganic filler to be added.
• the present invention provides an epoxy resin composition which causes little warping after molding or solder treatment in area mounting type semiconductor devices and is excellent in reliability of solder treatment or the like because it is especially excellent in adhesion to organic substrates, and a semiconductor device manufactured using the epoxy resin composition.
• a denotes a flexural modulus (N/mm 2 ) at molding temperature
• b denotes a cure shrinkage ( % )
• c denotes a heat shrinkage ( % ) of from molding temperature to room temperature
• a denotes a flexural modulus (N/mm 2 ) at molding temperature
• b denotes a cure shrinkage ( % )
• c denotes a heat shrinkage ( % ) of from molding temperature to room temperature
• the above epoxy resin composition wherein the cured product has a water absorption rate of not more than 0.2% by weight after the cured product is treated for 168 hours in an environment of 85 C C and 60% in relative humidity and the epoxy resin and/or the phenolic resin have/has a naphthalene skeleton, and to a semiconductor device manufactured by encapsulating semiconductor elements with said epoxy resin composition.
• FIG. 1 is a graph which shows relations of flexural modulus, cure shrinkage and heat shrinkage of the cured products of the epoxy resin compositions in examples and comparative examples.
• the molding temperature in the present invention means a temperature of a mold when the epoxy resin composition is cured by heating and is usually in the range of 160-190°C, but it is not limited to this temperature range.
• the value "a” is measured in accordance with JIS K 6911.
• the value "b+c” is obtained in the following manner.
• a cured product in the form of a disk of 100 mm in diameter and 3 mm in thickness is molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 70 kg/cm 2 and a curing time of 90 seconds, and inner diameter of the mold cavity at 175°C and outer diameter of the disk cured product at room temperature (25°C) are measured.
• the value "b+c” is calculated from the formula, [ ⁇ (inner diameter of the mold cavity at 175°C)- (outer diameter of the disk cured product at 25°C) ⁇ /( inner diameter of the mold cavity at 175°C)] X 100.
• the cured product used for evaluation is one which has not been subjected to post-curing treatment.
• the cured product obtained by heating and curing the epoxy resin composition of the present invention has a moisture absorption rate of not more than 0.20% by weight after the cured product is treated for 168 hours in an environment of 85 C C and 60% in relative humidity. If the moisture absorption rate exceeds 0.20% by weight, in the case of carrying out the solder bonding by solder treatment, water which is present in a semiconductor device due to the absorption from the cured product of the epoxy resin composition and the organic substrate, is abruptly vaporized at high temperatures to produce a stress, which causes cracking in the semicon- ductor device or separation at the interface between the semiconductor element-mounted side of the organic substrate and the cured product of the epoxy resin composition, resulting in deterioration of soldering crack resistance.
• the cured product used for measurement of the moisture absorption rate is one which is removed from the mold and then post-cured at 175 C C for 2 hours.
• the epoxy resins used in the present invention include all of monomers, oligomers and polymers having an epoxy group, for example, triphenolmethane type epoxy resins, biphenyl type epoxy resins, bisphenol type epoxy resins, stilbene type epoxy resins, o-cresol novolak type epoxy resins, epoxy resins having a naphthalene skeleton, and dicyclopentadiene type epoxy resins. These may be used each alone or in admixture. Especially, when epoxy resins having a naphthalene skeleton are used, flexural modulus at molding temperature is high, cure shrinkage and heat shrinkage of from molding temperature to room temperature are small, and moisture absorption rate is low, and, hence, these epoxy resins are preferred.
• the phenolic resins used in the present invention include all of monomers, oligomers and polymers having two or more phenolic hydroxyl groups capable of forming a crosslinked structure upon curing reaction with the above epoxy resins.
• examples thereof are phenolic novolak resins, cresol novolak resins, phenolic aralkyl resins such as p-xylylene-modified phenolic resins and m-xylylene • p- xylylene-modified phenolic resins, resins having a naphthalene skeleton, terpene-modified phenolic resins, and dicyclopentadiene-modified phenolic resins. These may be used each alone or in admixture.
• the curing accelerators used in the present invention are those which can act as catalysts for cross- linking reaction of the epoxy resin with the phenolic resin. Examples of them are 1,8-diazabicyclo (5,4,0 )- undecene-7, amine compounds such as tributylamine, organic phosphorus compounds such as triphenylphosphine, tetraphenylphosphonium • tetraphenyl borate, and imidazole compounds such as 2-methylimidazole.
• the curing accelerators are not limited to these examples. These may be used each alone or in admixture.
• the inorganic fillers used in the present invention have no special limitation and those generally used for encapsulating materials can be used. Examples thereof are fused silica, crystalline silica, secondary aggregation silica, alumina, titanium white, aluminum hydroxide, talc, clay, and glass fibers.
• the fused silica is especially preferred.
• the fused silica may be either in crushed or spherical form, but it is more preferred to use mainly spherical silica for increasing amount thereof to be added and inhibiting increase of melt viscosity of the epoxy resin composition.
• the proportion of a phenolic resin (B) is 20-300 parts by weight
• the proportion of a curing accelerator (C) is 0.1-30 parts by weight
• the proportion of an inorganic filler (D) is 200-2000 parts by weight on the basis of 100 parts by weight of an epoxy resin (A).
• the proportion of a phenolic resin (B) is less than 20 parts by weight, curing is insufficient, and when said proportion exceeds 300 parts by weight, the problem that uncured material remains is caused.
• the epoxy resin composition of the present invention may optionally contain, in addition to the components (A)-(D), various additives, for example, flame retardants such as brominated epoxy resin, antimony oxide and phosphorus compounds, inorganic ion exchangers, coupling agents, coloring agents such as carbon black, releasing agents such as natural wax, synthetic wax, higher fatty acids and metallic salts thereof and paraffin, low stress components such as silicone and rubber, and antioxidants.
• flame retardants such as brominated epoxy resin, antimony oxide and phosphorus compounds
• inorganic ion exchangers such as inorganic ion exchangers
• coupling agents coloring agents such as carbon black
• releasing agents such as natural wax, synthetic wax, higher fatty acids and metallic salts thereof and paraffin
• low stress components such as silicone and rubber, and antioxidants.
• the epoxy resin composition of the present invention is obtained by mixing the components (A) -(D) and other additives by a mixer, then heating and kneading the mixture by a kneader such as a heating kneader, a hot roll and an extruder, and cooling and grinding the kneaded product.
• a kneader such as a heating kneader, a hot roll and an extruder
• the composition can be cured and molded by conventional molding methods such as transfer molding, compression molding and injection molding.
• Example 1 10.2 Parts by weight of an epoxy resin represented by the following formula (1) (Epikote 1032H manufactured by Yuka Shell Epoxy Co., Ltd.; softening point: 60°C, epoxy equivalent: 170):
• Flexural modulus "a” at molding temperature Measurement was conducted in accordance with JIS K 6911 as mentioned above. A cured product was molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 70 kg/cm 2 and a curing time of 90 seconds, and the flexural modulus was measured at 175°C. The unit was N/mm 2 .
• a cured product in the form of a disk of 100 mm in diameter and 3 mm in thickness was molded using a transfer molding machine under the conditions of a mold temperature of 175 C C, an injection pressure of 70 kg/cm 2 and a curing time of 90 seconds, and inner diameter of the mold cavity at 175°C and outer diameter of the disk cured product at room temperature (25 C C) were measured.
• the value "b+c” was calculated from the formula, [ ⁇ (inner diameter of the mold cavity at 175°C)- (outer diameter of the disk cured product at 25°C) ⁇ /( inner diameter of the mold cavity at 175°C)] X 100.
• the unit was % .
• Moisture absorption rate A disk of 50 mm in diameter and 3 mm in thickness was molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 70 kg/cm 2 and a curing time of 90 seconds, and post-cured at 175°C for 2 hours. The cured product was further treated for 168 hours in an environment of 85°C and 60% in relative humidity, and change of weight was measured. The unit was % by weight.
• Warping amount of package A 225pBGA (BT resin substrate of 0.36 mm in thickness; chip size: 12 mm X 12 mm X 0.35 mm thick; package size: 24 mm X 24 mm; thickness of encapsulating resin: 1.17 mm) was molded using a transfer molding machine under the conditions of a mold temperature of 175°C, an injection pressure of 70 kg/cm 2 and a curing time of 90 seconds, and post-cured at 175°C for 2 hours. The cured product was cooled to room temperature, and, thereafter, displacement in the height direction was measured using a surface roughness meter in diagonal direction from the gate of the package. The largest value of displacement was taken as amount of warping. The unit was / tzm.
• Soldering crack resistance The above 225pBGA was molded, and post-cured at 175°C for 2 hours to obtain ten samples. These were treated for 168 hours in an environment of 60°C and 60% in relative humidity or in an environment of 85°C and 60% in relative humidity, and, then, treated by IR reflowing (240°C) for 10 seconds. The samples were observed by an ultrasonic defectoscope to examine the presence of internal cracks and various interfacial separations. When the number of defective packages was n, this was expressed by n/10.
• Releasability Releasability from the mold at the time of molding of the above 225pBGA was examined. The product which was not smoothly removable from the mold was judged to be bad.
• Examples 2-6 and Comparative Examples 1-6 Components were mixed in accordance with Tables 1 and 2, and epoxy resin compositions were prepared in the same manner as in Example 1 and these were evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2. Structures and properties of the epoxy resins and phenolic resins used in the examples and the comparative examples are shown below.
• Epoxy resin comprising a main component represented by the following formula (3) (YX-4000H manufactured by Yuka Shell Epoxy Co., Ltd.; melting point: 105°C, epoxy equivalent: 195):
• Epoxy resin represented by the following formula (4) (NC7000 manufactured by Nippon Kayaku Co., Ltd.; softening point: 90°C, epoxy equivalent: 225):
• Phenolic resin represented by the following formula (5) (softening point: 83°C, hydroxyl equivalent: 175) :
• Phenolic resin represented by the following formula (6) (softening point: 80°C, hydroxyl equivalent: 200) :
• Phenolic novolak resin softening point: 80°C, hydroxyl equivalent: 105.
• the area mounting type semiconductor devices obtained using the epoxy resin composition of the present invention are less in warping after molding or soldering treatment and excellent in soldering crack resistance.
• the epoxy resin composition of the present invention can be applied to encapsulating of various semiconductor devices and is especially suitable for BGA (ball grid array) and CSP (chip scale package).
• the semiconductor devices obtained by encapsulating with the resin composition of the present invention can be used for computers, liquid crystal display devices, portable telephones and the like.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Epoxy Resins (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Structures Or Materials For Encapsulating Or Coating Semiconductor Devices Or Solid State Devices (AREA)

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• 2000
  • 2000-09-04 WO PCT/JP2000/005992 patent/WO2001018115A1/en active IP Right Grant
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  • 2000-09-04 EP EP00956907A patent/EP1137708A1/de not_active Withdrawn
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