JP2007311821A - Resin sealed semiconductor device for surface mounting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin sealed semiconductor device for surface mounting which seals elements with a sealing epoxy resin composition capable of molding a mini package having no projection of a filler such as silica on the surface. <P>SOLUTION: The resin sealed semiconductor device for surface mounting seals the elements with the sealing epoxy resin composition containing an epoxy resin and a filler, where the filler contains 50 mass% or more of a crushed silica to the whole quantity of the filler, grains in a size of 30 μm or larger accounts for 0.2 mass% or lower to the whole grains of the filler, and the average grain size is 10 μm or smaller. The package is molded of the sealing epoxy resin composition, where the melt viscosity of the sealing epoxy resin composition is 50 Pa s or lower at a temperature of 175°C measured by using a Koka-type flow tester, and the sum of the length, the width, and the thickness is 5 mm or smaller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface-mount resin-encapsulated semiconductor device manufactured using an encapsulating epoxy resin composition used for encapsulating elements.

  More specifically, the present invention relates to a surface mount resin-encapsulated semiconductor device in which elements are protected by a mini package.

  Resin-encapsulated semiconductor devices constituting electronic devices are classified by function into individual semiconductor components such as transistors and diodes, and integrated circuit components such as ICs and LSIs. In general, the element is die-bonded to the lead frame and the lead wire (external terminal) of the lead frame is connected to the element with a wire such as an Au wire, and then the element is transferred to the epoxy resin composition by a transfer molding method. It is manufactured by sealing with the thermosetting resin composition. In the resin-encapsulated semiconductor device thus obtained, the element is protected by a package made of a cured thermosetting resin composition.

  In recent years, the mounting method of resin-encapsulated semiconductor devices has shifted from pin insertion mounting to surface mounting as electronic devices have become smaller and thinner. Such a change in mounting technology was mainly seen in the package of integrated circuit parts, but recently it has also been seen in the package of individual semiconductor parts mainly used for digital home appliances, communication equipment parts, and in-vehicle parts applications. . In addition, the miniaturization and thinning of packages are rapidly progressing, and so-called mini packages are widely formed.

  However, unfilled (voids) and the like are likely to occur when mini-packages are formed, and deterioration of productivity (yield) is a problem. Therefore, by expanding the gate dimension (gate size) of the mold as compared with the prior art, the molten thermosetting resin composition can easily flow into the cavity, thereby preventing the occurrence of unfilling. However, if the gate dimensions are increased as described above, burrs are likely to be generated in the gate portion of the mini-package, which is a molded product, so that it is necessary to remove the burrs by performing gate cutting (gate removal). In the case of gate cutting, a laser cutting method or the like is adopted. Usually, a filler such as silica mixed in the thermosetting resin composition protrudes from the surface of the molded product after gate cutting. There is a problem.

  Explaining the above problem a little more, conventionally, the gate size of a mold for forming a mini package has been mainly 300 to 500 μm square. If it is such a size, the silica currently distribute | circulated to the present market was enough as a filler mix | blended with a thermosetting resin composition. However, recently, the package has been further reduced in size and thickness, and the gate size has become 100 to 200 μm square. If it is such a size, if the current silica is no longer used, the gate will be clogged, unfilled will occur, and productivity will be reduced. Therefore, conversely, with an emphasis on improving productivity, the gate size is also set to 500 to 800 μm square, but as described above, such as silica that is blended in the thermosetting resin composition There is a new problem that the filler protrudes from the surface of the molded product after the gate cut.

  As a result, when the molded product is placed on the conveyor and transported, the molded product is tilted by the protrusion of the filler, and the molded product cannot be arranged on the conveyor in an orderly manner, or the protrusion of the filler interferes. It may become impossible to mount the molded product with high density.

  As described above, the conventional thermosetting resin composition makes it possible to form a mini package with high productivity and to prevent a filler such as silica from protruding from the surface of the mini package as a molded product. It was something that could not be done.

  The present invention has been made in view of the above points, and the device is protected by a package made of an epoxy resin composition for sealing, which can be molded with good productivity on a mini package in which a filler such as silica is not projected on the surface. It is an object of the present invention to provide a surface-mounted resin-encapsulated semiconductor device.

  A surface-mount resin-encapsulated semiconductor device according to claim 1 of the present invention is a surface-mount resin-encapsulated semiconductor device in which an element is encapsulated using an epoxy resin composition containing an epoxy resin and a filler. In a semiconductor device, as a filler, 50% by mass or more of the total filler is crushed silica, and those having a particle size of 30 μm or more are 0.2% by mass or less of the total filler and the average particle size is 10 μm or less. A vertical length and a horizontal length of a package molded with the above-mentioned epoxy resin composition for sealing having a melt viscosity at 175 ° C. of 50 Pa · s or less as measured using a Koka flow tester The sum of thickness and thickness is 5 mm or less.

  The invention of claim 2 is characterized in that, in claim 1, 70% by mass or more of the total filler is crushed silica.

  The invention of claim 3 is characterized in that, in claim 1 or 2, the epoxy resin is one or both of epoxy resins represented by the following formulas (1) and (2). is there.

  The invention of claim 4 is characterized in that, in claim 3, the content of the epoxy resin represented by the above formulas (1) and (2) is 20 to 100% by mass with respect to the total amount of the epoxy resin. is there.

  As described above, the resin-encapsulated semiconductor device for surface mounting according to claim 1 of the present invention is for surface mounting in which an element is encapsulated using an epoxy resin composition for encapsulation containing an epoxy resin and a filler. In a resin-encapsulated semiconductor device, as a filler, 50% by mass or more of the total filler is crushed silica, and those having a particle size of 30 μm or more are 0.2% by mass or less of the total filler and have an average particle size of 10 μm. Since the following epoxy resin composition for sealing is used, the filler does not protrude on the surface of the package after gate cutting, and at 175 ° C. measured using a Koka flow tester. Since the melt viscosity is 50 Pa · s or less, the productivity can be improved by suppressing the occurrence of wire flow and unfilling.

  In addition, since the surface-sealed resin-encapsulated semiconductor device according to claim 1 seals the element using the above-described epoxy resin composition for sealing, the surface of the package protecting the element has protrusions due to the filler. In addition, the sum of the vertical length, the horizontal length and the thickness of the package molded by the sealing epoxy resin composition is 5 mm or less, and is suitable for high-density mounting. It is.

  In the invention of claim 2, since 70% by mass or more of the total filler is crushed silica, increasing the proportion of crushed silica in the total filler can reduce the incidence of protrusions due to the filler. It can be done.

  In addition, since the invention of claim 3 uses any one or both of the epoxy resins represented by the above formulas (1) and (2) as the epoxy resin, the adhesive strength of the sealing epoxy resin composition to the element increases. Thus, high adhesion can be obtained, the moisture absorption rate of the epoxy resin composition for sealing can be reduced, and the occurrence of cracks during reflow heating can be prevented.

  Moreover, since content of the epoxy resin shown by said Formula (1) (2) is 20-100 mass% with respect to the epoxy resin whole quantity, invention of Claim 4 is said Formula (1) ( Of course, when only the epoxy resin shown in 2) is used, even when an epoxy resin other than these epoxy resins is used in combination, the reflow resistance and the moisture resistance can be sufficiently high.

  Embodiments of the present invention will be described below.

  The epoxy resin composition for sealing according to the present invention contains an epoxy resin and a filler.

  In the present invention, the epoxy resin is not particularly limited, but either one of a dicyclopentadiene type epoxy resin represented by the above formula (1) and a biphenyl type epoxy resin represented by the above formula (2) or It is preferred to use both. When these epoxy resins are used, the adhesive force of the epoxy resin composition for sealing to the element can be increased to obtain high adhesion, and the moisture absorption rate of the epoxy resin composition for sealing can be reduced. In addition, the occurrence of cracks during reflow heating can be prevented.

  Particularly recently, when surface mounting a package, environmentally-friendly lead-free solder has been used. Since this lead-free solder has a higher melting point than conventional solder and a higher temperature during reflow heating, the package requires better reflow resistance (reflow heat resistance) and moisture resistance than the conventional solder. However, if such an epoxy resin is used, this requirement can be sufficiently met.

  In addition to the epoxy resins represented by the above formulas (1) and (2), for example, orthocresol novolac type epoxy resins, biphenyl type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, bisphenol A type epoxy resins, Various polyfunctional epoxy resins such as brominated epoxy resins can be used. When the epoxy resin represented by the above formulas (1) and (2) is used in combination with another epoxy resin, the content of the epoxy resin represented by the above formulas (1) and (2) is 20 with respect to the total amount of the epoxy resin. It is preferable that it is -100 mass%. If the content is less than 20% by mass, the reflow resistance and moisture resistance may not be sufficiently high.

  In the present invention, crushed silica, spherical silica, flaky silica, and the like can be used as the filler, but it is necessary to satisfy all of the following three conditions.

  First, it is necessary that 50% by mass or more of the total filler (substantially upper limit is 100% by mass) is crushed silica. Crushed silica can be obtained by pulverizing crystalline silica, fused silica or the like. When less than 50% by mass of the total filler is crushed silica, protrusions due to fillers such as silica are often observed at the gate portion of the molded product after gate cutting. 70% by mass or more of the total filler is preferably crushed silica, and more preferably 90% by mass or more of the total filler is crushed silica. Thus, as the ratio of crushed silica in the total filler increases, the occurrence rate of protrusions due to the filler can be reduced.

  Second, the particle size of 30 μm or more needs to be 0.2% by mass or less (substantially lower limit is 0% by mass) of the total filler. When the particle size of 30 μm or more exceeds 0.2% by mass of the total filler, the rate of occurrence of protrusions due to the filler increases.

  Third, it is necessary that the average particle size is 10 μm or less (the practical lower limit is 3 μm). When the average particle diameter exceeds 10 μm, unfilling occurs during molding, resulting in a decrease in productivity, and protrusions due to the filler remain in the molded product even after gate cutting after molding.

  In addition, the compounding quantity of a filler can be set to 70-93 mass% with respect to the epoxy resin composition for sealing.

  The epoxy resin composition for sealing according to the present invention contains the above-mentioned epoxy resin and filler, but the following components can be blended as necessary.

  That is, various polyhydric phenol compounds such as a phenol novolak resin, a cresol novolak resin, and a phenol aralkyl resin can be used as the curing agent. About the usage-amount of an epoxy resin and a hardening | curing agent, it is preferable that the hydroxyl group in a hardening | curing agent is 0.5-1.5 equivalent with respect to 1 equivalent of epoxy groups of an epoxy resin, 0.8-1.2 equivalent It is more preferable that

  Further, as the curing aid, phosphorus-based materials, imidazole-based materials such as 2-phenylimidazole (2PZ), and amine-based materials can be used. Two or more curing aids can be used in combination, but the curing aid is preferably blended in an amount of 0.01 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin.

  Moreover, as a mold release material, carnauba wax, stearic acid, montanic acid, carboxyl group-containing polyolefin, or the like can be used.

  In addition to the above components, silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, flame retardants such as brominated epoxy resins and antimony trioxide, colorants such as carbon, and silicone flexibility imparting agents are added. be able to.

  The epoxy resin composition for sealing according to the present invention is blended with the above epoxy resin and filler, further blended with other components as necessary, and mixed with a mixer, blender or the like, and then kneader. It can be prepared by heating and kneading with a roll or roll. Further, the kneaded product may be cooled and solidified as necessary, and pulverized to be used in the form of powder.

  In the sealing epoxy resin composition prepared as described above, the melt viscosity at 175 ° C. measured using a Koka flow tester is 50 Pa · s or less (substantially lower limit is 10 Pa · s). is there. The Koka type flow tester is a constant load type orifice extrusion type flow that pushes the test material in a heated cylinder from the orifice with a plunger with a constant load and expands and records the descending speed of the plunger at this time. A type of tester, proposed by the Society of Polymer Science. If the melt viscosity at a temperature substantially equal to the molding temperature (175 ° C.) is 50 Pa · s or less as described above, the microbubbles are expelled without damaging the wire during bending, such as bending or disconnection. The epoxy resin composition for sealing in a molten state can be allowed to flow into the cavity, and as a result, a molded product in which both the wire flow and unfilled are reduced can be obtained. Further, since the generation of defective products can be suppressed in this way, productivity can be maintained high. However, if the melt viscosity at 175 ° C. exceeds 50 Pa · s, many defective products with wire flow and unfilling will be obtained, and the yield will be reduced. Although the melt viscosity may be increased by using the filler described above, it is easy to lower the melt viscosity to 50 Pa · s or less by appropriately selecting the epoxy resin to be used. is there.

  By sealing the element using the above-described sealing epoxy resin composition, the following resin-encapsulated semiconductor device can be manufactured.

  That is, when manufacturing a package of individual semiconductor components as a resin-encapsulated semiconductor device, it can be performed as follows. For example, using a silicon chip as an element, the silicon chip is die-bonded to a lead frame having three lead wires, and each lead wire of the lead frame and the silicon chip are connected by a wire such as an Au wire. Is set in a transfer mold, and transfer molding is performed, whereby a transistor in which a silicon chip is sealed with a sealing epoxy resin composition can be manufactured.

  On the other hand, when manufacturing a QFP (quad flat package) as an integrated circuit component as a resin-encapsulated semiconductor device, it can be performed as follows. For example, an integrated circuit (IC) chip is used as an element, and the integrated circuit chip is die-bonded to a lead frame provided with a plurality of lead wires on four sides, and each lead wire of the lead frame and the integrated circuit chip are Au wires. The integrated circuit component QFP is manufactured by sealing the integrated circuit chip with the sealing epoxy resin composition by connecting the wire with a wire, etc., and setting it in a transfer molding die. It is something that can be done.

  In the resin-encapsulated semiconductor device manufactured as described above, in any case of individual semiconductor components and integrated circuit components, an epoxy resin composition for encapsulation molding these packages Since the filler satisfying all the above-described three conditions is used, the filler does not protrude from the surface of the package after the gate cut. In addition, molding is performed using an epoxy resin composition for sealing whose melt viscosity at 175 ° C. measured with a Koka flow tester is 50 Pa · s or less, so that productivity is suppressed by suppressing the occurrence of wire flow and unfilling. Can be increased.

  In addition, by sealing the element using the above-described sealing epoxy resin composition, a surface-mounted resin-encapsulated semiconductor device can be manufactured. In this surface-mounting resin-encapsulated semiconductor device, the sum of the vertical length, horizontal length and thickness of the package molded from the above-described epoxy resin composition for sealing is 5 mm or less (the practical lower limit is 2 mm). Degree). A package having such a small external dimension is referred to as a mini package in the present invention. However, when molding the mini package, the sealing epoxy resin composition according to the present invention is particularly preferably used and exhibits its true value. Is. Here, since the external dimensions of the mini-package are considerably small, elements having only one active function such as simple signal processing, such as amplification, control, and conversion, are suitable as elements protected by the mini-package. Specifically, it is a single-function element such as a transistor, diode, LED, or semiconductor laser, and the lead frame to which such an element is die-bonded has an average of 2 to 4 lead wires and a maximum of 8 lead wires. It is. In other words, the epoxy resin composition for sealing according to the present invention is suitable for manufacturing a mini package of individual semiconductor components to be mounted at a high density.

  Manufacturing a mini-package of individual semiconductor components as a surface-mounted resin-encapsulated semiconductor device can be performed as follows. For example, using a silicon chip as an element, the silicon chip is die-bonded to a lead frame having three lead wires, and each lead wire of the lead frame and the silicon chip are connected by a wire such as an Au wire. Is set in a transfer mold, and transfer molding is performed, whereby a transistor in which a silicon chip is sealed with a sealing epoxy resin composition can be manufactured.

  Even when the gate size of the mold is as narrow as 100 to 200 μm square at the time of the transfer molding, if the filler satisfies all the above three conditions, the gate is not clogged, It is possible to suppress the occurrence of unfilling and prevent a decrease in productivity. Even when the gate size of the mold is as wide as 500 to 800 μm square, the above three conditions as a filling material are satisfied. If a filling material is used, the filler will not protrude from the surface of the molded product after gate cutting. That is, regardless of the case where the gate size of the mold is 100 to 800 μm square, the epoxy resin composition for sealing according to the present invention is that the mini package is molded with high productivity and is a molded product. It is possible to achieve both the fact that the filler such as silica does not protrude from the surface of the mini package. Needless to say, the same effect as described above can be obtained even in a resin-encapsulated semiconductor device in which the sum of the vertical length, horizontal length, and thickness of the package exceeds 5 mm.

  Hereinafter, the present invention will be specifically described by way of examples.

(Raw material of epoxy resin composition for sealing)
As an epoxy resin, “EOCN195XL-3” manufactured by Sumitomo Chemical Co., Ltd. which is an o-cresol novolac type epoxy resin, Dainippon Ink and Chemicals, Inc. which is a dicyclopentadiene type epoxy resin represented by the above formula (1) “HP7200” manufactured by Yuka Shell Epoxy Co., Ltd., which is a biphenyl type epoxy resin represented by the above formula (2), was used.

  In addition, “PSM6200” manufactured by Gunei Chemical Industry Co., Ltd., which is a phenol novolac resin, was used as a curing agent.

  As the flame retardant, “ESB400T” manufactured by Sumitomo Chemical Co., Ltd. and antimony trioxide, which are brominated epoxy resins, were used.

  Carnauba wax was used as a release material, carbon was used as a colorant, and 2-phenylimidazole (2PZ) was used as a curing aid.

  Silica as shown in Table 1 was used as the filler. That is, “MCF-200” manufactured by Tatsumori Co., Ltd. (referred to as “C”), “FS-20” manufactured as Electrochemical Industry Co., Ltd. (referred to as “B”), and electricity. “FS-5DC” manufactured by Chemical Industry Co., Ltd. (substantially removed particles having a particle size of 20 μm or more is referred to as (A)), and “FB-” manufactured by Denki Kagaku Kogyo Co., Ltd., which is spherical silica. 60 ”(referred to as (D)),“ FB-8S ”(referred to as (E)) manufactured by Denki Kagaku Kogyo Co., Ltd. and“ FB-5SDC ”(referred to as (E)) F)) was used. Any silica was used after being treated with γ-glycidoxypropyltrimethoxysilane.

(Preparation of epoxy resin composition for sealing)
The above components are blended in the blending amounts shown in Table 2 and Table 3, and mixed for 3 minutes with a blender, homogenized, then kneaded with a roll heated to 100 ° C. for 10 minutes, cooled, and then predetermined with a pulverizer. By pulverizing to a particle size, a granular molding material composed of an epoxy resin composition for sealing was obtained.

  For the molding materials of Examples 1 to 6 and Comparative Examples 1 to 8 thus obtained, the gel time, spiral flow and melt viscosity at 175 ° C. were measured. A Koka flow tester was used to measure the melt viscosity. The results are shown in Tables 2 and 3.

(Evaluation of molded products)
O Unfilled occurrence rate Using the molding materials of Examples 1 to 6 and Comparative Examples 1 to 8, transfer molding was performed on a mold for molding a mini package having a gate size of 100 μm × 800 μm. This was continuously performed to obtain 22400 mini packages (vertical length: 1.6 mm + horizontal length: 0.85 mm + thickness: 0.7 mm = 3.15 mm). The molding conditions were molding temperature: 185 ± 5 ° C., injection speed: 8 seconds, injection pressure: 15 MPa, cure time: 40 seconds, and after-curing at 175 ° C. for 6 hours after molding.

  Each mini package was visually inspected for unfilled, and the number of unfilled out of 22400 mini packages was counted. The results are shown in Tables 2 and 3.

Occurrence rate of protrusion of gate part 224 mini packages were randomly extracted from the 22400 mini packages obtained as described above, and the gate part was observed with a microscope. Mini-packages with protrusions of 20 μm or more were counted, and the gate portion protrusion occurrence rate was determined by the following equation.

Protrusion rate of gate part (%) = (Number of mini-packages with protrusions / 224) × 100
The results are shown in Tables 2 and 3.

○ Wire flow, reflow resistance, moisture resistance reliability Using the molding materials of Examples 1 to 6 and Comparative Examples 1 to 8, transfer molding was performed on a mold for 80-pin QFP having an outer shape of 15 mm × 19 mm × 2.4 mm in thickness. . Molding conditions are molding temperature: 185 ± 5 ° C., injection speed: 8 seconds, injection pressure: 15 MPa, cure time: 40 seconds, and after-curing at 175 ° C. for 6 hours after molding, a package for performance evaluation is obtained. It was.

-Wire flow The inside of 10 performance evaluation packages was observed with soft X-rays. "X" includes one or more packages with a sweep rate of 10% or more with respect to the straight line between the two ends of the wire, and includes packages with a sweep ratio with respect to the straight line between the two ends of the wire of 10% or more. Those not present were determined as “◯”, and the results are shown in Tables 2 and 3.

-Reflow resistance The package for performance evaluation was allowed to stand for 168 hours in an atmosphere at a temperature of 85 ° C. and a humidity of 85% RH to absorb moisture, followed by IR reflow (EIAJ standard) to observe the presence or absence of package cracks. In Tables 2 and 3, the number of packages observed in the denominator is shown, and the number of packages in which cracks occurred in the numerator is shown.

-Moisture resistance reliability After the reflow-treated package was left in an atmosphere of a temperature of 133 ° C. and a humidity of 100% RH for 500 hours, the occurrence of open defects was inspected. In Tables 2 and 3, the number of packages inspected in the denominator is shown, and the number of packages in which an open defect has occurred in the numerator is shown.

  As can be seen in Tables 2 and 3, it is confirmed that all of Examples 1 to 6 have a low protrusion occurrence rate. Moreover, even if the package is continuously formed, it is confirmed that productivity is good because there is no unfilling and the wire flow is low.

  Moreover, it is confirmed that those of Examples 1 to 3 using the epoxy resin represented by the above formulas (1) and (2) as the epoxy resin are excellent in reflow resistance and moisture resistance reliability.

  On the other hand, it is confirmed that all of Comparative Examples 1 to 8 cannot simultaneously form the package with high productivity and do not allow a filler such as silica to protrude from the surface of the package. . That is, those of Comparative Examples 1 to 4 and 8 have poor productivity due to high unfilled incidence and wire flow, and those of Comparative Examples 1 to 7 have high protrusion occurrence rates.

Claims (4)

  In a surface-mounted resin-encapsulated semiconductor device in which an element is encapsulated using an epoxy resin composition for encapsulation containing an epoxy resin and a filler, 50% by mass or more of the total filler is crushed silica as a filler. The particle size of 30 μm or more is 0.2% by mass or less of the total filler, and the average particle size is 10 μm or less, and at 175 ° C. measured using a Koka flow tester. Surface mount resin characterized in that the sum of the vertical length, the horizontal length and the thickness of the package molded by the sealing epoxy resin composition having a melt viscosity of 50 Pa · s or less is 5 mm or less Sealed semiconductor device.   The resin-encapsulated semiconductor device for surface mounting according to claim 1, wherein 70% by mass or more of the total filler is crushed silica. 3. The resin-encapsulated semiconductor device for surface mounting according to claim 1, wherein any one or both of epoxy resins represented by the following formulas (1) and (2) are used as the epoxy resin: .

  The resin-encapsulated semiconductor device for surface mounting according to claim 3, wherein the content of the epoxy resin represented by the above formulas (1) and (2) is 20 to 100% by mass with respect to the total amount of the epoxy resin. .