JP4872587B2 - Sealing film and semiconductor device using the same - Google Patents

Description

  The present invention relates to a sealing film and a semiconductor device using the same.

  Higher frequency, lighter, thinner and smaller mobile communication devices represented by mobile phones (spreading of mobile phones equipped with TV functions) are advancing. Along with this, the demand for surface acoustic wave (SAW) filters for removing radio wave noise has increased, and SAW filters are also required to be smaller and lighter.

  In order to reduce the size and weight, a CSP (chip size package) type SAW filter has been proposed. A CSP-type SAW filter can be manufactured by mounting a large number of miniaturized SAW filter chips (hereinafter also referred to as SAW chips) on a substrate, sealing the chip, and then dicing the substrate into individual pieces. it can.

  When the SAW chip is mounted on the substrate, the surface of the SAW chip on which the SAW electrode of the SAW chip is formed (hereinafter also referred to as the SAW electrode surface) is the surface of the substrate on which the SAW chip connection wiring pattern is formed ( Hereinafter, it is also arranged on the substrate so as to face the substrate surface), and the SAW electrodes are connected to the wiring pattern of the substrate by bumps. In the SAW chip, when the SAW electrode surface for generating the surface acoustic wave comes into contact with another member, the generation of the surface acoustic wave may be inhibited. Further, when other members come into contact with a substrate that propagates a surface acoustic wave, for example, quartz, the surface acoustic wave propagation may be inhibited. Therefore, when the SAW chip is sealed with a material (sealing material) such as resin, it is necessary to prevent the SAW electrode surface and the substrate surface from being contaminated by the sealing material. That is, a space corresponding to the height of the bump provided between the SAW chip and the substrate surface must be maintained in a hollow state in the SAW filter.

  In order to achieve the above, a method of forming a protective layer for protecting the SAW chip has been proposed (see, for example, Patent Document 1). In this method, first, SAW chips are arranged on the substrate at a height corresponding to the height of the bumps, and then, using a film such as an epoxy resin film, the end of the film is placed on the substrate surface (SAW chip and The SAW chip is covered so as to reach the surface of the wiring pattern to be connected), and further, a resin such as a liquid UV-curable resin is applied to the film surface (the surface opposite to the surface in contact with the SAW chip), Harden.

Japanese Patent Laid-Open No. 11-17490

  However, the above method requires a complicated and long process. Therefore, an object of the present invention is to provide a sealing film that can easily obtain a SAW device having excellent reliability without causing the SAW electrode surface and the substrate surface to be contaminated by the sealing material. And Another object of the present invention is to provide a semiconductor device using the sealing film.

  As a result of intensive studies by the inventors of the present invention, it has been found that the above-mentioned problems can be solved by a sealing film including a layer A and a layer B having a specific viscosity.

The present invention comprises an A layer and a B layer, the lowest shear viscosity in the temperature range of 80 ° C. or more and 150 ° C. or less of the A layer is 1,000 Pa · s or more and less than 50,000 Pa · s, and the B layer is 80 ° C. or more. The present invention relates to a sealing film having a minimum shear viscosity of 50,000 Pa · s or more in a temperature range of 150 ° C. or lower.
The sealing film is preferably a sealing film used for a surface acoustic wave device, the surface acoustic wave device has a surface acoustic wave chip, a substrate and a sealing film, and the surface acoustic wave chip is a surface acoustic wave. The electrode surface of the wave chip is arranged on the substrate so as to face the substrate, the electrode of the surface acoustic wave chip is connected to the substrate through the bump, and there is a space between the surface acoustic wave chip and the substrate, and the elastic surface The wave chip is sealed with a sealing film, and the B layer of the sealing film is used so as to contact the surface opposite to the electrode surface of the surface acoustic wave chip, the side surface of the surface acoustic wave chip, and the substrate.
In the sealing film, the A layer has a thickness of (a + b) μm or more and ((a + b) × 2) μm or less, and the B layer has a thickness of (b × 1/10) μm or more and b μm or less. preferable. Here, a is the thickness of the surface acoustic wave chip, and b is the height of the bump.
Furthermore, as for the said sealing film, it is preferable that A layer and B layer contain a thermosetting component, and a thermosetting component contains an epoxy resin and a hardening | curing agent.
Moreover, the A layer contained in the sealing film is preferably (1) a thermosetting component having a softening point or a melting point of −40 to 50 ° C., (2) a high molecular weight component having a weight average molecular weight of 100,000 or more, And (3) containing an inorganic filler, the content of the high molecular weight component is 5 to 100 parts by weight based on 100 parts by weight of the thermosetting component, and the content of the inorganic filler is 40 to the volume of the entire A layer. 80% by volume.
Furthermore, the elastic modulus at 200 ° C. of the cured product obtained by curing the A layer is preferably 100 MPa or more, and the average linear expansion coefficient in the temperature range of 25 to 150 ° C. is preferably 40 ppm or less.
Moreover, it is preferable that the breaking elongation in 25 degreeC of B layer contained in the said sealing film is 50% or more and 500% or less.
Another aspect of the present invention relates to a semiconductor device in which a semiconductor chip is sealed using the sealing film. The semiconductor chip is preferably a surface acoustic wave chip.

  With the sealing film of the present invention, the semiconductor chip can be satisfactorily embedded and sealed in the sealing film, and a highly reliable semiconductor device can be easily obtained. In particular, there is no contamination due to the flow of resin between the semiconductor chip electrode surface and the substrate surface, and a SAW device having excellent reliability can be easily obtained. According to the sealing film of the present invention, the semiconductor chip can be easily sealed by a single heat press.

  The sealing film of this invention consists of a structure containing 2 layers of A layer and B layer. The sealing film may be composed of only two layers of the A layer and the B layer, but may further have an arbitrary layer. As a sealing film having an arbitrary layer, for example, a sealing film in which an A layer and a B layer are laminated on a base material layer, an A layer and a B layer are laminated on a base material layer, and further a protection is provided thereon. There is a sealing film in which films are laminated, and a sealing film having an intermediate layer between an A layer and a B layer. When sealing the chip, the base material layer and the protective film are removed.

  The sealing film of the present invention is preferably used as a sealing material for SAW devices. The use of the sealing film is not limited to this, and for example, it can be used as a sealing material for chip mounted devices such as CSP packages, and small devices such as resistors and electric filters used in IT equipment. When sealing the SAW chip, the B layer is preferably an inner layer, that is, a layer in contact with the SAW chip. In this case, the A layer is an outer layer, that is, a layer that becomes the surface of the SAW device. Hereinafter, although the case where it uses for a SAW device is demonstrated to an example about the sealing film of this invention, this invention is not limited to this.

  FIG. 1 is a schematic cross-sectional view showing an example of a SAW device 1 in which a SAW chip 3 is sealed with a sealing film 2 of the present invention. The SAW device 1 includes at least a SAW chip 3, a substrate 6, and a sealing film 2. The SAW chip 3 is arranged so that the electrode surface 7 faces the substrate 6. A wiring pattern 11 for connecting a SAW chip is formed on the surface of the substrate 6 facing the SAW chip 3. The electrode 4 of the SAW chip 3 is connected (adhered) to the wiring pattern of the substrate 6 via the bump 5, and a height corresponding to the height of the bump 5 is approximately between the electrode surface 7 of the SAW chip 3 and the substrate 6. There is a space 8. The SAW chip 3 is sealed with a sealing film 2. The B layer 10 of the sealing film 2 is in contact with the surface opposite to the electrode surface 7 of the SAW chip 3 and the side surface of the SAW chip 3, and the B layer of the outer peripheral portion 2a of the sealing film 2 is in contact with the substrate surface. In FIG. 1, 9 is an A layer, and 11 is a wiring pattern for connecting a SAW chip provided on a substrate.

  When sealing a SAW chip using a sealing film, the SAW chip is embedded in the sealing film. The sealing film desirably has appropriate fluidity so that the chip is not damaged when the chip is embedded at a temperature of 80 ° C. or higher and 150 ° C. or lower. Therefore, from the viewpoint of chip embeddability, the lowest shear viscosity of the A layer in the temperature range of 80 ° C. or more and 150 ° C. or less is 1,000 Pa · s or more and less than 50,000 Pa · s. Furthermore, it is preferably 5,000 Pa · s or more and less than 20,000 Pa · s. If the minimum shear viscosity is less than 1,000, the fluidity of the film is large, the thickness of the sealing film varies, and the surface of the SAW device cannot be kept flat. On the other hand, when it is 50,000 Pa · s or more, the fluidity is deteriorated, and the chip cannot be embedded in the sealing film with a pressure that does not damage the chip.

  The B layer desirably has low fluidity in order to prevent the resin from flowing between the chip and the substrate and to maintain a sufficient gap between the chip and the substrate. The lowest shear viscosity of the B layer in the temperature range of 80 ° C. or higher and 150 ° C. or lower is 50,000 Pa · s or higher. If the minimum shear viscosity of the B layer is less than 50,000 Pa · s, the flowability of the resin is large, the resin flows between the chip and the substrate, and a sufficient gap cannot be maintained. The lowest shear viscosity of the B layer is preferably 50,000 Pa · s or more and 300,000 Pa · s or less, and more preferably 80,000 Pa · s or more and 200,000 Pa · s or less.

  In the present invention, the lowest shear viscosity is obtained by using a rotary rheometer and sandwiching the A layer or the B layer in a parallel disk (diameter 8 mm) with a gap width 2 to 5 μm smaller than each layer thickness, a frequency of 1 Hz, a strain of 1%, It can be determined as the value of the complex viscosity when measured at a temperature increase rate of 5 ° C./min. The measurement is performed on the layer in the B stage state.

  The A layer has a viscosity suitable for satisfactorily embedding the chip, and the B layer has a viscosity suitable for maintaining a space between the chip and the substrate. In the SAW chip, the A layer of the sealing film becomes the surface layer of the SAW device, and the B layer is sealed in a state where the B layer is in contact with the chip and the substrate.

  In order to embed the chip, the thickness of the A layer is preferably (a + b) μm or more ((a + b) × 2) μm or less. Here, a is the thickness of the surface acoustic wave chip, and b is the height of the bump. If the thickness is less than (a + b) μm, the thickness may be insufficient and the chip may not be sufficiently embedded. Moreover, it is preferable not to exceed ((a + b) × 2) μm from the viewpoint of miniaturization of the filter.

  On the other hand, since it is necessary to maintain a gap between the chip and the substrate, the thickness of the B layer is preferably (b × 1/10) μm or more and b μm or less. If the thickness of the B layer is less than (b × 1/10), the B layer may break during sealing, and the A layer may flow between the chip and the substrate. On the other hand, if it exceeds b μm, the embedding property of the entire sealing film may be lowered, and chip embedding may be difficult.

  Although there is no limitation in particular about the chip thickness amicrometer, it is 50-300 micrometers normally, Preferably it is 100-200 micrometers. The height b of the bump is not particularly limited, but is usually 25 to 100 μm, preferably 50 to 80 μm.

  The A layer and the B layer in the present invention are not particularly limited as long as the components have the above viscosity.

  The A layer preferably contains a thermosetting component. Furthermore, in order for the A layer to have the above viscosity, (1) a thermosetting component having a softening point or melting point of −40 ° C. to 50 ° C., (2) a high molecular weight component having a weight average molecular weight of 100,000 or more, and ( 3) It is preferable to contain an inorganic filler, the content of the high molecular weight component is 5 to 100 parts by weight with respect to 100 parts by weight of the thermosetting component, and the content of the inorganic filler is 40 to 40% with respect to the volume of the entire A layer. 80% by volume is particularly preferred.

  There is no restriction | limiting in particular as a thermosetting component used for A layer. Examples of the thermosetting component that can be used include an epoxy resin, a cyanate resin, a phenol resin, and, if necessary, a curing agent thereof. An epoxy resin is preferable because of its high heat resistance. Epoxy resins include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolak type such as phenol novolac type epoxy resin and cresol novolak type epoxy resin. An epoxy resin or the like can be used. Moreover, what is generally known, such as a polyfunctional epoxy resin, a glycidyl amine type epoxy resin, a heterocyclic ring-containing epoxy resin, an alicyclic epoxy resin, can be applied. An epoxy resin can be used individually or in combination of 2 or more types.

  As bifunctional epoxy resin, Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 807, 815, 825, 827, 828, 834, 1001, 1004, 1007, 1009, Dow Chemical Co., trade name: DER-330 301, 361, manufactured by Tohto Kasei Co., Ltd., trade names: YD-8125, YDF-8170, YDF-8170C, and the like.

  As the phenol novolac type epoxy resin, Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 152,154, Nippon Kayaku Co., Ltd., trade name: EPPN-201, Dow Chemical Company, trade name: DEN-438, etc. However, as an o-cresol novolak type epoxy resin, Nippon Kayaku Co., Ltd., trade name: EOCN-102S, 103S, 104S, 1012, 1025, 1027, Toto Kasei Co., Ltd., trade name: YDCN701,702 , 703, 704 and the like.

  As the polyfunctional epoxy resin, Yuka Shell Epoxy Co., Ltd., trade name: Epon 1031S, Ciba Specialty Chemicals, trade name: Araldite 0163, Nagase Kasei Co., Ltd., trade name: Denacol EX-611, 614 614B, 622, 512, 521, 421, 411, 321 and the like. As amine type epoxy resin, Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 604, Toto Kasei Co., Ltd., trade name: YH-434, Mitsubishi Gas Chemical Co., Ltd., trade names: TETRAD-X, TETRAD- C, manufactured by Sumitomo Chemical Co., Ltd., trade name: ELM-120 and the like.

  Examples of the heterocyclic ring-containing epoxy resin include Ciba Specialty Chemicals, trade name: Araldite PT810, UCC, trade names: ERL4234, 4299, 4221, 4206, and the like.

  Moreover, the well-known hardening | curing agent used normally can be used as a hardening | curing agent of an epoxy resin. For example, bisphenols having two or more phenolic hydroxyl groups in one molecule such as amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, bisphenol A, bisphenol F, bisphenol S, phenol novolac resins, bisphenol A Examples thereof include phenolic resins such as novolac resin and cresol novolac resin.

  Phenol resins such as phenol novolac resin, bisphenol A novolak resin, and cresol novolac resin are particularly preferable in terms of excellent electric corrosion resistance when absorbing moisture. Preferable phenolic resin-based curing agents include, for example, Dainippon Ink Chemical Co., Ltd., trade names: Phenolite LF2882, Phenolite LF2822, Phenolite TD-2090, Phenolite TD-2149, Phenolite VH-4150, Phenolite Light VH4170 etc. are mentioned.

  Regarding the A layer, the softening point or melting point of the thermosetting component excluding the curing agent is preferably −40 ° C. to 50 ° C. A thermosetting component can be used individually or in combination of 2 or more types. When combining 2 or more types, it is preferable that the softening point or melting | fusing point of the thermosetting component which is a combined mixture is -40 degreeC-50 degreeC. When the softening point or melting point is less than −40 ° C., the film-forming property may be inferior, and when the softening point or melting point exceeds 50 ° C., the viscosity increases and the flowability may decrease. The softening point can be measured by the ring and ball method.

  The softening point or melting point of the curing agent is preferably 60 ° C. or higher and 150 ° C. or lower. When the softening point or melting point is less than 60 ° C., the heat resistance of the cured product may not be sufficiently obtained. Moreover, when the softening point or melting | fusing point of a hardening | curing agent exceeds 150 degreeC, the fluidity | liquidity of a film may fall.

  The high molecular weight component used in the A layer has a weight average molecular weight of 100,000 or more, particularly 200,000 to 3,000,000 from the viewpoints of film handling, film strength, flexibility, and tackiness. Preferably, it is 300,000 to 1,000,000. If the weight average molecular weight is less than 100,000, film properties may be deteriorated. In the present invention, the weight average molecular weight is a value measured by gel permeation chromatography and converted using a standard polystyrene calibration curve.

  Such high molecular weight components include polyimide resin, (meth) acrylic resin, urethane resin, polyphenylene ether resin, polyetherimide resin, phenoxy resin, modified polyphenylene ether resin, polystyrene resin, polyethylene resin, polyester resin, polyamide resin, Examples thereof include, but are not limited to, butadiene rubber, acrylic rubber, acrylonitrile butadiene rubber, polycarbonate resin, polyphenylene ether resin, and mixtures thereof.

  Among them, the glass transition temperature (hereinafter referred to as “Tg”) of the high molecular weight component is preferably from −50 ° C. to 20 ° C. This is because when the Tg is −50 ° C. or higher, the tackiness of the adhesive layer in the B-stage state is appropriate, and there is no problem in handling properties. Moreover, when manufacturing high molecular weight components, such as an acrylic rubber (polymer), using a monomer, there is no restriction | limiting in particular as the polymerization method, For example, methods, such as pearl polymerization and solution polymerization, can be used.

  The amount of the high molecular weight component is preferably 5 to 100 parts by weight with respect to 100 parts by weight of the thermosetting component. If it is less than 5 parts by weight, the strength of the film before curing is low, the elongation of the film becomes small, and the handleability may be lowered. If it exceeds 100 parts by weight, the flowability may decrease. More preferably, it is 5-80 weight part, More preferably, it is 5-50 weight part.

  For the purpose of reducing the linear expansion coefficient of the A layer, improving the mechanical strength, and improving the laser marking properties, the A layer preferably contains an inorganic filler. The content of the inorganic filler is preferably 40 to 80% by volume with respect to the total volume of the A layer. More preferably, it is 50-80 volume%, and it is further more preferable that it is 65-75 volume%.

  Inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, aluminum nitride, aluminum borate whisker, boron nitride, crystalline silica, non Crystalline silica, antimony oxide, and the like can be used, and two or more of these can be used in combination. In order to improve thermal conductivity, alumina, aluminum nitride, boron nitride, crystalline silica, amorphous silica and the like are preferable. For the purpose of adjusting melt viscosity and imparting thixotropic properties, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, crystalline silica, non-crystalline silica Crystalline silica and the like are preferred. Furthermore, alumina and silica are preferable because the resin does not remain on the cutting blade during film cutting, and the film can be cut and separated into pieces in a short time.

  The shape of the inorganic filler is not particularly limited, such as needle shape, scale shape, plate shape, and spherical shape, but a spherical filler that can obtain a relatively high fluidity even when the filler is contained in a high ratio is preferable. .

  The average particle size of the inorganic filler is preferably 0.1 μm or more and 20 μm or less from the viewpoint of film fluidity and surface smoothness. More preferably, it is 0.3 μm or more and 10 μm or less. When the lower limit of the average particle diameter is less than 0.1 μm, the specific surface area of the filler increases, and the fluidity may decrease due to the surface effect. On the other hand, if the average particle size exceeds 20 μm, the smoothness of the film may be lowered. In the present invention, the particle size distribution of the filler is measured, and the particle size at which the cumulative weight is 50% in the particle size distribution is defined as the average particle size. The particle size distribution of the filler can be measured using, for example, a laser diffraction type particle size distribution measuring device (Nikkiso Microtrack).

  It is preferable that the cured product obtained by curing the A layer has an average coefficient of linear expansion of 40 ppm or less in a temperature range of 25 to 150 ° C. from the viewpoint of reducing warpage of the sealing film when used in a package. Preferably they are 3 ppm or more and 40 ppm or less, More preferably, they are 3 ppm or more and 30 ppm or less, More preferably, they are 5 ppm or more and 20 ppm or less. If the average linear expansion coefficient is less than 3 ppm or exceeds 40 ppm, the difference between the average linear expansion coefficients of the substrate and the sealing film increases, and stress is generated due to temperature change, and peeling or sealing of the interface with the substrate. Cracks may occur in the stop film. In order to make the average linear expansion coefficient of A layer into the said range, compared with organic substance (thermosetting component and high molecular weight component), an inorganic filler with a low thermal expansion coefficient is 40-80 with respect to the whole volume of A layer. It is preferable to contain by volume%.

  In the present invention, the average linear expansion coefficient is determined by measuring the elongation of a sample at a heating rate of 5 ° C. per minute for a heat-cured layer using a thermomechanical analyzer, and extending in a temperature range of 25 ° C. to 150 ° C. It can be calculated as an average value.

  Moreover, in order to maintain the reliability at high temperature, it is preferable that the elastic modulus of the hardened | cured material obtained by hardening | curing A layer is 100 Mpa or more at 200 degreeC. More preferably, it is 100 MPa or more and 5,000 MPa or less, More preferably, it is 300 MPa or more and 1,000 MPa or less. When the elastic modulus is less than 100 MPa, reflow cracks due to insufficient strength may occur, and when the elastic modulus exceeds 5,000 MPa, the effect of mitigating thermal stress is small, and peeling or cracks may occur.

  In this invention, the elasticity modulus of hardened | cured material can be calculated | required as a storage elastic modulus in 200 degreeC using a dynamic viscoelasticity measuring apparatus (tensile mode) about the heat-hardened layer.

  Next, the B layer preferably contains a thermosetting component. As a thermosetting component used for B layer, the same thermosetting component as the above-mentioned A layer is mentioned. The B layer preferably contains a high molecular weight component in addition to the thermosetting component from the viewpoint of the above-mentioned viscosity and from the viewpoint of elongation at break, and the content of the high molecular weight component is preferably a thermosetting component. It is preferable that the content is larger than the content.

  Examples of the high molecular weight component used in the B layer include the same high molecular weight components as those in the above-described A layer, and among them, polyimide resin, acrylic rubber, acrylonitrile butadiene rubber (NBR), and the like are preferable. From the viewpoint of elongation at break, it preferably contains a high molecular weight component such as rubber or elastomer.

  When the B layer and the A layer are laminated together, the high molecular weight component used for the B layer is the same as the high molecular weight component used for the A layer (polyimide resin, Acrylic rubber, NBR, etc.), and more preferably the same as the high molecular weight component used in the A layer.

  The amount of the high molecular weight component is preferably 50 to 500 parts by weight with respect to 100 parts by weight of the thermosetting component. If it is less than 50 parts by weight, the elongation at break may decrease. If it exceeds 500 parts by weight, the flowability may decrease. More preferably, it is 100-400 weight part, More preferably, it is 150-300 weight part.

  Furthermore, the B layer may contain an inorganic filler for the purpose of improving heat resistance by increasing the elastic modulus at high temperature and adjusting the viscosity. As an inorganic filler, the same inorganic filler as the above-mentioned A layer is mentioned. The content of the inorganic filler is preferably less than 50% by volume and more preferably less than 10% by volume with respect to the total volume of the B layer. If the content of the inorganic filler is 50% by volume or more, the elongation at break may be insufficient. The average particle diameter of the inorganic filler is preferably 0.1 μm or less from the viewpoint of improving the surface smoothness and heat resistance of the film. In addition, when the average particle size is less than 10 nm, the specific surface area of the filler is increased, it becomes difficult to disperse the filler in the film, and the fluidity of the film may be extremely reduced. Preferably there is.

  The layer B preferably has an elongation at break of 50% or more and 500% or less. When the elongation at break is less than 50%, the elongation of the B layer is insufficient, the sealing film cannot cope with the unevenness of the chip and the substrate, and the chip may not be embedded well. If it exceeds 500%, the resin may flow under the chip. In order to make the breaking elongation of the B layer within the above range, it is preferable to include a high molecular weight component such as rubber or elastomer.

  In the present invention, the elongation at break is determined by conducting a tensile test on the layer in the B-stage state, and ((L−L0) / L0) × 100 (L0: distance between gauge points before the test, L: distance between gauge points at the time of break. (Mm)).

  The A layer and / or the B layer may contain a colorant, a curing accelerator, a catalyst, an additive, a coupling agent, and the like in addition to the thermosetting component, the high molecular weight component, and the inorganic filler. . Moreover, it is preferable that the transmittance | permeability of the area | region with a wavelength of 300-1100 nm is 10% or less, respectively for A layer and / or B layer. It is preferable that A layer and / or B layer contain a coloring agent. Examples of the colorant that can be used include pigments and dyes such as carbon black, graphite, titanium carbon, manganese dioxide, and phthalocyanine. It is also possible to cause the inorganic filler to act as a colorant.

  The content of the colorant is preferably 0.1 to 10% by weight, more preferably 0.5 to 2.0% by weight, based on the weight of the whole A layer or the whole B layer. If the content of the colorant is less than 0.1% by weight, the film may not be colored and the laser marking may be poorly visible when laser marking is performed. On the other hand, when the content of the colorant exceeds 10% by weight, problems such as an increase in ionic impurities, a decrease in film ductility, or a decrease in adhesive strength with a semiconductor chip may occur.

  Further, since the laser used for laser marking is often a YAG laser, it is preferable to use carbon black which is easily volatilized by the YAG laser as the colorant.

  In addition, the sealing film of this invention should just consist of a structure containing 2 layers of A layer and B layer, and there is no prescription | regulation in particular regarding the manufacturing method of the film containing 2 layers. For example, a film A composed of an A layer and a film B composed of a B layer are produced, and the film A or the film B is softened at a softening temperature (preferably 80 to 120 ° C.), or both are thermocompressed or a laminator is used. Can be manufactured.

  The A layer and the B layer can be prepared by coating and drying a resin varnish containing, for example, the thermosetting component, the high molecular weight component, the inorganic filler, and the colorant on the base material layer. As a base material layer used for these, a conventionally well-known thing can be used without being restrict | limited in particular. The resin varnish can be obtained by adding a solvent such as cyclohexanone to the above components and stirring and mixing them.

  The thickness of the A layer after drying is preferably 50 to 200 μm, and more preferably 50 to 150 μm. Moreover, it is preferable that the thickness after drying of B layer is 7-75 micrometers, and it is more preferable that it is 10-50 micrometers.

  In addition, you may use A layer and B layer, after laminating | stacking multiple layers and adjusting a film thickness, respectively. A laminator or the like can be used for the lamination.

  As a base material layer used, plastic films, such as a polytetrafluoroethylene film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, a polyimide film, etc. are mentioned, for example. Further, surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment, etching treatment, mold release treatment and the like may be performed on the surface of the base material layer as necessary. The thickness of a base material is not specifically limited, It is preferable that it is 38-100 micrometers.

  The base material layer may have adhesiveness, and an adhesive layer may be provided on one side of the base material layer. The pressure-sensitive adhesive layer can be formed by applying and drying a resin varnish having an appropriate tack strength including a low molecular weight component (tackifier such as a terpene compound) and a high molecular weight component adjusted for Tg.

  Moreover, it is preferable to protect the A layer or the B layer with a protective film. Examples of the protective film include plastic films such as a polytetrafluoroethylene film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, and a polyimide film. Further, surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment, etching treatment, mold release treatment and the like may be performed as necessary. The base material layer may be used as a protective film. You may install a protective film on A layer and B layer which were provided on the base material layer. The thickness of a protective film is not specifically limited, It is preferable that it is 10-100 micrometers.

  As the usage of the sealing film, the same usage as a conventional solid or liquid sealing material can be considered. As a usage method, for example, a sealing film with a base material layer (base material film) is laminated on a substrate on which a semiconductor chip or a component is mounted using a hot plate press, a laminator, and the like. There is a way to peel off the layers. Moreover, after peeling off a base material layer, it can also heat-harden.

  More specifically, after laminating a sealing film with a base layer on a semiconductor chip bonded by bumps on a substrate using a hot plate press, the base layer is peeled off at a temperature of 140 to 170 ° C. There are methods such as heat curing for 1 to 5 hours. Furthermore, steps such as surface polishing can be taken as necessary. When laminating the sealing film, the temperature, pressure, and time are appropriately set in order to fill the semiconductor chip. For example, in order to fill a 100 μm semiconductor chip with a 130 μm sealing film of the present invention, a temperature of 100 to 150 ° C., a pressure of 0.4 to 1 MPa, and 1 to 1000 s are preferable, and 4 to 10 s are more preferable.

  Further, for example, there is a method in which two substrates on which semiconductor chips and components are mounted are laminated using a hot plate press, a laminator, etc. with a sealing film sandwiched so that the mounted surfaces face each other, and then heat-cured.

  Hereinafter, although the Example demonstrates the sealing film of this invention concretely, this invention is not limited to this.

(Film A1)
Bisphenol F type epoxy resin (epoxy equivalent 175, melting point −15 ° C., using YDF-8170C manufactured by Tohto Kasei Co., Ltd.) 50 parts by weight as thermosetting component (epoxy resin), low as thermosetting component (curing agent) Water-absorbing phenol resin (softening point: 76.5 ° C., using XLC-LL manufactured by Mitsui Chemicals), silica filler (average particle size: 8.0 μm, TFC-24 manufactured by Tatsumori Co., Ltd.) as an inorganic filler 530 parts by weight, carbon black as a colorant, 1.5 parts by weight, epoxy group-containing acrylic rubber as a high molecular weight component (weight average molecular weight 850,000, using HTR-860P-3 manufactured by Nagase ChemteX Corporation) 18 Parts by weight, 1-cyanoethyl-2-phenylimidazole (Curesol 2PZ manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a curing accelerator Using CN) 0.5 parts by weight, and, cyclohexanone 500 parts by weight were mixed and stirred as a solvent, to obtain a resin varnish.

  The obtained resin varnish was coated on a base film with a release agent as a base material layer (Purex A31 manufactured by Teijin Limited), dried at 90 ° C. for 10 minutes and 120 ° C. for 20 minutes, and had a thickness of 100 μm. Film A1 was obtained. In this case, the volume fraction of the inorganic filler was 69%. Further, two films A1 having a thickness of 100 μm were bonded at 80 ° C. using a laminator to obtain a film A1 having a thickness of 200 μm.

(Film A2)
As thermosetting component (epoxy resin), bisphenol F type epoxy resin (epoxy equivalent 175, melting point -15 ° C., using YDF-8170C manufactured by Tohto Kasei Co., Ltd.) 44 parts by weight and cresol novolac type epoxy resin (epoxy equivalent 220, Softening point 80 ° C, YDCN-703 manufactured by Toto Kasei Co., Ltd.) 15 parts by weight, bisphenol A type novolak resin (softening point 130 ° C, manufactured by Dainippon Ink & Chemicals, Inc.) as a thermosetting component (curing agent) LF-2882 used) 41 parts by weight, silica filler as an inorganic filler (average particle size 0.5 μm, Admafine SO-C2 manufactured by Admatech Co., Ltd.) 143 parts by weight, epoxy group-containing acrylic rubber (high molecular weight component) Weight average molecular weight 850,000, HTR-860P made by Nagase ChemteX Corporation 42 parts by weight, 0.5 part by weight of 1-cyanoethyl-2-phenylimidazole (used as a cure sol 2PZ-CN manufactured by Shikoku Kasei Co., Ltd.) as a curing accelerator, and 1000 parts by weight of cyclohexanone as a solvent. A film A2 having a thickness of 25 μm and 100 μm was obtained in the same manner as the film A1 except that it was used. The mixture of the bisphenol F type epoxy resin and the cresol novolac type epoxy resin was a viscous liquid at room temperature (25 ° C.) (the softening point or melting point of the mixture was not more than room temperature). In this case, the volume fraction of the inorganic filler was 34%. Further, two films A2 having a thickness of 100 μm were bonded at 80 ° C. using a laminator to obtain a film A2 having a thickness of 200 μm.

(Film A3)
A film A3 having a thickness of 115 μm was obtained in the same manner as the film A1, except that 245 parts by weight of silica filler (average particle size: 8.7 μm, FB-35 manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as the inorganic filler. In this case, the volume fraction of the inorganic filler was 50%. Further, two films A3 having a thickness of 115 μm were bonded at 80 ° C. using a laminator to obtain a film A3 having a thickness of 230 μm.

(Film A4)
A film A4 having a thickness of 100 μm was obtained in the same manner as the film A1, except that a silica filler (average particle size of 3.9 μm, TFC-12 manufactured by Tatsumori Co., Ltd. was used) was used as the inorganic filler. In this case, the volume fraction of the inorganic filler was 69%. Further, two films A4 having a thickness of 100 μm were bonded at 80 ° C. using a laminator to obtain a film A4 having a thickness of 200 μm.

(Film B1)
Cresol novolac type epoxy resin (epoxy equivalent 220, softening point 80 ° C., using YDCN-703 manufactured by Tohto Kasei Co., Ltd.) 60 parts by weight as thermosetting component (epoxy resin), low as thermosetting component (curing agent) Water-absorbing phenolic resin (softening point 76.5 ° C., using XLC-LL manufactured by Mitsui Chemicals) 40 parts by weight, silica filler (average particle size 16 nm, using R972V manufactured by Nippon Aerosil Co., Ltd.) 32 weights Parts, epoxy group-containing acrylic rubber (weight average molecular weight 850,000, using HTR-860P-3 manufactured by Nagase ChemteX Corporation) as a high molecular weight component, 200 parts by weight, 1-cyanoethyl-2-phenylimidazo- as a curing accelerator Le (uses Shikoku Kasei Co., Ltd. Curesol 2PZ-CN) 0.5 parts by weight, Shiku as the solvent A film B1 having a thickness of 10 μm and 50 μm was obtained in the same manner as the film A1 except that 1500 parts by weight of rohexanone was used. In this case, the volume fraction of the inorganic filler was 4.5%. Further, two or four films B1 having a thickness of 50 μm were bonded at 80 ° C. using a laminator to obtain films B1 having a thickness of 100 μm and 200 μm.

  Various characteristics of the obtained film in a B stage state (after solvent drying) and a C stage state (after heat curing) were evaluated. For the evaluation, the following method was used. The evaluation results are shown in Table 1.

(Evaluation methods)
(1) Minimum shear viscosity A sample obtained by cutting a film whose thickness was adjusted to 130 μm or more and less than 260 μm into 10 mm × 10 mm was used. When the thickness of the single film was less than 130 μm, a plurality of sheets were laminated so as to be 130 μm or more. Specifically, the films were laminated at a temperature at which curing did not proceed (80 ° C.) so that peeling did not occur on the bonded surface during the shear viscosity measurement. Shear viscosity was measured by using a rotational rheometer (RES, manufactured by Rheometric Scientific, ARES), and sandwiching the film in a parallel disk (diameter 8 mm) with a gap width 2 to 5 μm smaller than the film thickness, with a frequency of 1 Hz and a strain of 1%. It is the value of the complex viscosity when measured from 30 ° C. to 300 ° C. (heating rate 5 ° C./min). The lowest value of the complex viscosity in the temperature range from 80 ° C to 150 ° C was defined as the lowest shear viscosity.

(2) Elastic modulus (storage elastic modulus)
The storage elastic modulus at 200 ° C. of the film heat-cured at 170 ° C. for 1 hour was measured using a dynamic viscoelasticity measuring device (DVE-V4, manufactured by Rheology) (sample size: length 20 mm, width 4 mm, film thickness). 100 μm or 115 μm, heating rate 5 ° C./min, tensile mode 10 Hz, automatic static load, temperature range −50 to 300 ° C.).

(3) Average linear expansion coefficient For a film (thickness: 100 μm or 115 μm) heat-cured at 170 ° C. for 1 hour, a sample was heated at a rate of 5 ° C. per minute using a thermomechanical analyzer (Seiko Instruments, SS6100). The average linear expansion coefficient was determined from the elongation from 25 ° C to 150 ° C.

(4) Elongation at break A film having a thickness of 100 μm or 115 μm was cut into 10 mm × 100 mm, and marked lines having an interval of 50 mm were attached. The elongation at break of the film was measured at room temperature (23 ° C. ± 2 ° C.) with a tensile speed of 50 mm / min. Elongation at break (%) = ((L−L0) / L0) × 100 (L0: distance between gauge points before test (50 mm), L: distance between gauge points at break (mm)).

  The films used in Examples and Comparative Examples and their thicknesses are shown in Table 2. For Examples 1 to 6 and Comparative Examples 1 to 3, two were selected from the films in Table 1, and two films were bonded together at 80 ° C. using a laminator to produce a sealing film. For Comparative Examples 4 and 5, one was selected from the films in Table 1, and a single-layer film was used as the sealing film.

  The sealing film obtained was evaluated for fillability, flowability, and solder heat resistance. For the evaluation, the following method was used. The evaluation results are shown in Table 2.

(Filling (embedding) property)
A die bond film (manufactured by Hitachi Chemical Co., Ltd., model number: die bonding film HS-230, 25 μm thickness, 5 mm × 5 mm) was placed on the slide glass as a substitute for the bumps. Furthermore, a glass chip (150 μm thickness, 10 mm × 10 mm) is placed on the die bond film so that the die bond film is positioned at the center of the glass chip, and is subjected to thermocompression bonding at 150 ° C., 0.1 MPa for 3 seconds, and a test element (Fig. 2). A sealing film (25 mm × 25 mm) was placed on the glass chip so that the B layer in Table 2 was in contact with the glass chip, and pressed using a hot plate at 120 ° C. and 0.7 MPa for 5 seconds. The glass chip is observed with an optical microscope, and the ratio of the sealing film in contact with the glass chip side surface (the ratio of the length of the sealing film in contact with the glass chip side surface to the length of the glass chip side surface (chip outer periphery) ) Was calculated. When the ratio was 95% or more, it was evaluated as “◯”, 85% or more and less than 95% as Δ, and less than 85% as ×.

(Flow (penetration) property)
A test sample was prepared in the same manner as the evaluation method for filling property, and a sealing film was placed on a glass chip and pressed. The glass chip was observed with an optical microscope, and the maximum value of the distance at which the sealing film flowed from the end of the glass chip toward the inside was measured. The distance of flow was less than 50 μm, ◯, 50 μm or more and less than 100 μm, Δ, and 100 μm or more as x.

(Solder heat resistance)
A test element was prepared in the same manner as the evaluation method of filling property, and a sealing film was placed on a glass chip and pressed to obtain three samples in which the glass chip was sealed with the sealing film. These elements were cured at 170 ° C. for 1 hour, and then floated (floated) for 1 minute on a 240 ° C. soldering iron, and the presence or absence of blistering and peeling was observed visually and with an optical microscope. The case where no blistering or peeling was observed was marked with ○, the case where one or more blistering or peeling was observed was marked with Δ, and the case where blistering or peeling was observed on all was marked with ×.

The sealing films of Examples 1 to 6 were all excellent in filling property, flow-in (soaking) property, and solder heat resistance.
In addition, when a semiconductor chip is sealed by a conventional method, that is, a semiconductor chip is covered with a film such as an epoxy resin film, and further a resin such as a liquid ultraviolet curable resin is applied to the film surface and cured. However, the surface of the obtained semiconductor device was not flat. On the other hand, when the semiconductor chip was sealed using the sealing film of the present invention, a semiconductor device having a flat surface was obtained.

FIG. 1 is a schematic cross-sectional view showing an example of a SAW device in which a SAW chip is sealed with a sealing film of the present invention. FIG. 2 is a schematic cross-sectional view of a test element for evaluating fillability.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 SAW device 2 Sealing film 2a Outer part 3 of sealing film 3 SAW chip 4 Electrode 5 Bump 6 Substrate 7 Electrode surface 8 Space 9 A layer 10 B layer 11 Wiring 21 Glass chip 22 Die bond film 23 Slide glass 24 Test element

Claims (8)

A layer and a B layer are provided, the lowest shear viscosity in the temperature range of 80 ° C. to 150 ° C. of the A layer is 1,000 Pa · s to less than 50,000 Pa · s, and the B layer has a temperature of 80 ° C. to 150 ° C. A sealing film having a minimum shear viscosity of 50,000 Pa · s or more in a temperature range, which is used for a surface acoustic wave device, the surface acoustic wave device has a surface acoustic wave chip, a substrate, and a sealing film, and is elastic The surface acoustic wave chip is disposed on the substrate so that the electrode surface of the surface acoustic wave chip faces the substrate, the electrode of the surface acoustic wave chip is connected to the substrate via the bump, and the surface acoustic wave chip is interposed between the surface acoustic wave chip and the substrate. The surface acoustic wave chip is sealed with a sealing film, and the B layer of the sealing film is a surface opposite to the electrode surface of the surface acoustic wave chip, the side surface of the surface acoustic wave chip, and the substrate. Sealing film, characterized by being used in contact. The thickness of the layer A (a + b) μm or more ((a + b) × 2 ) is at [mu] m or less, the sealing film of claim 1, wherein the thickness of the layer B (b × 1/10) is [mu] m or more bμm less. Here, a is the thickness of the surface acoustic wave chip, and b is the height of the bump. The sealing film according to claim 1 or 2, wherein the A layer and the B layer contain a thermosetting component, and the thermosetting component contains an epoxy resin and a curing agent. Layer A contains (1) a thermosetting component having a softening point or melting point of −40 to 50 ° C., (2) a high molecular weight component having a weight average molecular weight of 100,000 or more, and (3) an inorganic filler, 5 to 100 parts by weight content with respect to 100 parts by weight of the thermosetting component of ingredient claims 1-3 or the content of the inorganic filler is 40 to 80% by volume based on the volume of the entire layer a The sealing film as described. And the elastic modulus at 200 ° C. of the cured product obtained by curing the layer A 100MPa or more, sealing of the average linear expansion coefficient is 40ppm or less claim 1-4, wherein either a temperature range from 25 to 150 ° C. the film. The sealing film according to any one of claims 1 to 5 , wherein the elongation at break of the B layer at 25 ° C is from 50% to 500%. The semiconductor device which sealed the semiconductor chip using the sealing film in any one of Claims 1-6 . The semiconductor device according to claim 7 , wherein the semiconductor chip is a surface acoustic wave chip.

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