JP2006019714A - Manufacturing method of electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method superior in moldability in hollow portion capable of reducing the generation of voids, even in the case of a chip coming-off substrate or the like, if the hollow mold of SAW device or the like is sealed with resin in a batch, using a gelatinous thermosetting resin sheet. <P>SOLUTION: In the manufacturing process having the following processes (a) to (d), functional devices loaded on a wiring substrate are covered with the gelatinous thermosetting resin sheet and are cured, by heating to seal a hollow between the substrate and the devices with the resin in batch. (a) The resin sheet is disposed so as to cover a plurality of the aligned functional devices that face the substrate by providing the air-gap between the devices and the substrate on the wiring substrate. (b) Vacuum is created in a closed spatial region, surrounded by the resin sheet enclosing the functional devices and the substrate. (c) With the closed spatial region being kept in vacuum, the sealing resin surface is formed flat, while the resin sheet is heated and fluidized at a temperature lower than the curing temperature with a hot roll. (d) The resin sheet is cured by heating to the curing temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a plurality of arranged functional elements placed facing each other with a space between the wiring board and the wiring board are placed on the wiring board so as to cover these functional elements. The present invention relates to a method for manufacturing an electronic component that uses a resin sheet and performs resin sealing at once with a high yield while keeping a space between a wiring board and a functional element hollow.

  In recent years, a large number of electronic components in which functional elements are hollow-molded on a wiring board are used in various electronic devices such as mobile phones. Typical examples of such a device include a surface acoustic wave device, a crystal resonator, and a piezoelectric resonator. Such an electronic component must prevent the active surface of the functional element from being sealed with a resin. For example, in a surface acoustic wave device, a surface acoustic wave electrode is formed on a surface acoustic wave chip. Since the performance cannot be exhibited if the sealing resin or the substrate surface and the surface acoustic wave electrode come into contact with each other when the resin sealing is performed on the wiring substrate, the resin sealing must be performed while the electrode surface is kept hollow. On the other hand, such electronic components have been miniaturized, and their manufacture is also a so-called MAP (mold array package) shape in which a large number of small functional element chips, for example, surface acoustic wave chips, are arranged by flip chip bonding. However, a system in which a large number of functional element chips on a substrate are encapsulated at once is becoming mainstream. In this specification, the resin sealing while keeping the space between the wiring board and the functional element hollow is called a hollow mold. Also, collectively sealing a large number of elements arranged on a substrate at once is called collective resin sealing. Note that a vacuum means a state of a space filled with a gas having a pressure lower than the normal atmospheric pressure.

  Conventionally, as a collective resin sealing technique for such a hollow mold electronic component, for example, a method of sealing a void using a heat-melt type member (see, for example, Patent Document 1), a surface acoustic wave chip and a film A surface acoustic wave device packaging method (see, for example, Patent Document 2) that is covered with resin and then sealed with a resin, and a surface acoustic wave filter packaging method in which a deformed plastic film is laminated by sucking air from a hole provided in the substrate ( For example, refer to Patent Document 3), a method in which a surface acoustic wave chip on a substrate is coated with a gel-like curable resin sheet in the air, and then heat-pressed in the air (for example, refer to Patent Document 4). It has been known. However, with these methods, it has been difficult to form a hollow mold with high accuracy and high productivity. In other words, the chip arrangement on the substrate has chip missing in order to eliminate defective products in the manufacturing process, and the chip arrangement and chip size differ depending on the product. For example, it is inevitable that the sealing resin flows too much under the chip, the sealing sheet does not reach the substrate surface, or a void is generated at the chip edge portion. It was. In addition, the method of sealing with a deformed plastic film is not suitable for stacking and mounting of packages because the surface of the protective layer is not flat. Therefore, a manufacturing method based on a collective resin sealing technique that enables a high yield of the hollow mold has not been known.

International Publication No. WO97 / 02596 Pamphlet Japanese Patent Laid-Open No. 11-17490 Japanese Patent Laid-Open No. 2001-176955 JP 2003-17979 A

  In view of the above-mentioned present situation, the present invention is excellent in moldability of the hollow portion when the hollow mold such as the surface acoustic wave device is encapsulated on the substrate using the gel-like curable resin sheet, and the chip is removed. An object of the present invention is to provide a manufacturing method excellent in reliability and productivity that can reduce the generation of voids in the case of a substrate or the like and can solve the above-described problems.

As a result of intensive studies to solve the above problems, the present inventor surprisingly significantly reduced the occurrence of the above-mentioned defects by combining gel-curing resin sheets under vacuum and then molding with a hot roll. Based on this finding, the present invention has been completed.
That is, according to the present invention, a plurality of arranged functional elements placed facing each other with a space between the wiring board and the wiring board are arranged on the wiring board so as to cover the plurality of arranged functional elements. A method for producing an electronic component in which a gel-like curable resin sheet disposed thereon is heat-cured to encapsulate resin while keeping a space between the wiring board and the functional element, and at least the following: A method for manufacturing an electronic component comprising the steps (a), (b), (c) and (d) of:
(A) a step of disposing a gel-like curable resin sheet on the wiring board so as to cover the plurality of arranged functional elements placed facing each other with a gap provided between the wiring board and the wiring board;
(B) a step of evacuating a closed space region surrounded by the gel-like curable resin sheet and the wiring board in which the plurality of arranged functional elements are included;
(C) The step of forming the sealing resin surface flat while heating and flowing the gel-like curable resin sheet below the curing temperature with a hot roll while maintaining the closed space region in a vacuum, and
(D) A step of curing the gel-like curable resin sheet by heating to a curing temperature.

According to the present invention, when a hollow mold electronic component, for example, a surface acoustic wave device or the like is collectively resin-sealed on a wiring board, the hollow mold can be accurately formed even if there is a chip loss. it can.
According to the present invention, when the surface acoustic wave device or the like is collectively resin-sealed on the wiring substrate, a good product with less resin penetration under the chip and no void in the outer periphery of the chip can be manufactured. it can.
Further, according to the present invention, the above-described configuration can easily manufacture a MAP-shaped electronic component having a product thickness and having a flat protective resin surface and encapsulated in a batch with a high yield.
Hereinafter, the present invention will be described in detail.

In the manufacturing method of the present invention, in order to prevent the wiring pattern and the active surface from coming into contact with each other, the active surface of the functional element chip placed on the wiring substrate facing the wiring pattern is provided with a gap. An electronic component sealed with a protective resin is manufactured. Examples of such functional elements include surface acoustic wave chips, piezoelectric vibrator chips, crystal vibrator chips, sensor chips, and the like. The active surface is a surface on which, for example, a surface acoustic wave electrode, a piezoelectric vibrator, a crystal vibrator, and a sensor are formed in the functional element. If such a surface is sealed with a resin or the like or comes into contact with the substrate surface, physical vibrations of the electrodes and the vibrator are hindered and the function is not performed. In the sensor, the contact with the detection substance is hindered and the function is not performed. Therefore, when sealing with a protective resin, it is necessary to leave the upper part of such an active surface hollow. On the other hand, along with the miniaturization of these electronic components, for example, in a surface acoustic wave device, a chip having a size of 2 mm square or less is used, and as a manufacturing method, a substrate on which a fine wiring pattern is formed on the surface In addition, a method is used in which a large number of chips are arranged by flip chip bonding, a large number of chips are collectively sealed with resin, and then dicing into individual devices.
The manufacturing method of the present invention is suitably applied to the collective resin sealing step in the above manufacturing method, and the above four steps (a) to (d) are essential steps. Hereinafter, each of these steps will be described.

Step (a)
In this step, a gel-like curable resin sheet is disposed on the wiring board so as to cover the plurality of arranged functional elements placed facing each other with a space between the wiring board and the wiring board. For the above-mentioned gap between the functional element and the wiring board, for example, a method of inserting a spacer such as a particle shape or a planar shape or securing the gap at the height of the flip chip bump for flip chip bonding should be adopted. Can do. A plurality of functional elements are usually arranged in an array on the substrate. However, the functional elements may be in an arbitrary arrangement and are not necessarily in a regular arrangement. In addition, a group of chip groups in which a certain number of chips are arranged in each region divided on the substrate may be arranged, and a plurality of such chip groups may be arranged on the substrate. Note that application of the present invention to a single chip is not excluded. The gel-like curable resin sheet includes, for example, a group of chips arranged so as to form a closed space region surrounded by the wiring board so as to include the plurality of arranged functional elements therein. It is arranged so as to cover the entire group and also cover the substrate portion around the entire chip group.

  The gel-like curable resin sheet can be produced, for example, by sheeting a mixture of a liquid or solid curable composition and a thermoplastic resin powder that acts as a gelling agent. Note that the gelling agent for the solid curable composition is intended to enable gelation even when heated and melted.

  Specific examples of the liquid or solid curable composition include, for example, epoxy resins, phenoxy resins, phenol resins, unsaturated polyester resins, alkyd resins, urethane resins, melamine resins, urea resins, guanamine resins, polyimide resins, vinyls. Examples thereof include a curable composition containing a thermosetting resin such as an ester resin, diallyl phthalate resin, xylene resin, or silicon resin as a resin component. These may be used alone or in combination of two or more. Among these, the epoxy resin composition is preferable because it has a low viscosity and is suitable for imparting other functions such as filler filling.

  The above-mentioned epoxy resin composition generally contains an epoxy resin, a curing agent and / or a latent curing accelerator, a filler used as necessary, such as silica and alumina, and other additives (excluding a gelling agent). Composition.

  There is no restriction | limiting in particular in the said epoxy resin, If it is generally used for various uses as an epoxy resin, it can be used.

  Specific examples of the epoxy resin include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, hydrogenated bisphenol A type epoxy resin, phenol novolac type epoxy resin, alicyclic aliphatic epoxy resin, Examples thereof include glycidyl ethers of organic carboxylic acids, prepolymers of the above epoxy resins, copolymers of the above epoxy resins such as polyether modified epoxy resins and silicone modified epoxy resins and other polymers. These may be used alone or in combination of two or more. Among these, bisphenol A type epoxy resin and bisphenol F type epoxy resin are preferable from the viewpoints of good heat resistance and water resistance, low cost and economical.

  As the curing agent, those conventionally used can be used. Specific examples thereof include phenolic curing agents, dicyandiamide curing agents, urea curing agents, organic acid hydrazide curing agents, and polyamine salts. Type curing agent, amine adduct type curing agent and the like. These may be used alone or in combination of two or more. Of these, phenol-based curing agents are preferred from the standpoints of low outgassing during curing, moisture resistance, heat cycle resistance, and the like. A dicyandiamide curing agent, a urea curing agent, an organic acid hydrazide curing agent, a polyamine salt curing agent, and an amine adduct curing agent are latent curing agents, and are preferable from the viewpoint of storage stability.

  The latent curing agent preferably has an activation temperature of 60 ° C. or higher, more preferably 80 ° C. or higher. The upper limit of the activation temperature is preferably 250 ° C. or less, and more preferably 180 ° C. or less from the viewpoint of being able to improve productivity at high temperature and above, fast curability.

  The amount of the curing agent to be used varies depending on the type of the curing agent, and thus cannot be specified unconditionally. Usually, the number of functional group equivalents of the curing agent is 0.5 to 1 per equivalent of epoxy group. 0.5 equivalents, more preferably 0.7-1 equivalents, especially 0.8-1 equivalents.

  As the latent curing accelerator, those conventionally used can be used, but those having an active temperature of 60 ° C. or higher, more preferably 80 ° C. or higher are preferable from the viewpoint of storage stability. The upper limit of the activation temperature is preferably 250 ° C. or less, and more preferably 180 ° C. or less from the viewpoints of high curing acceleration at the activation temperature and higher, and productivity can be improved.

  Specific examples of the latent curing accelerator include a modified imidazole curing accelerator, a modified aliphatic polyamine accelerator, and a modified polyamine accelerator. These may be used alone or in combination of two or more. Of these, modified imidazole-based curing accelerators are preferable from the viewpoints of high activity temperature, good reactivity, and high purity.

  The amount used in the case of using the latent curing accelerator varies depending on the type of the latent curing accelerator, and thus cannot be defined unconditionally, but is usually 1 to 80 parts per 100 parts of epoxy resin, and further 5 It is preferably ~ 50 parts.

  The thermoplastic resin powder that acts as the gelling agent absorbs and swells the liquid curable composition to become a gel, or becomes compatible with the liquid curable composition to become a gel. Anything to do.

  Specific examples of the thermoplastic resin include, for example, polyvinyl chloride, polyethylene, polypropylene, polystyrene, synthetic rubber (polybutadiene, butadiene-styrene copolymer, polyisoprene, polychloroprene, ethylene-propylene copolymer), polyvinyl acetate. Poly (meth) acrylic acid ester, polyacrylic acid amide, polyoxymethylene, polyphenylene oxide, polyester, polyamide, polycarbonate, cellulose resin, polyacrylonitrile, thermoplastic polyimide, polyvinyl alcohol, polyvinylpyrrolidone and the like. These may be used alone or in combination of two or more. Among these, polymethacrylic acid esters such as polymethyl methacrylate are preferable from the viewpoint of sheet formability.

  The softening temperature, molecular weight, etc. of the thermoplastic resin cannot be generally defined, but in general, the softening temperature is 50 to 150 ° C. in terms of the sheeting temperature and the reactivity of the epoxy resin. The molecular weight is preferably 3 million or less, more preferably 1 million or less.

  The average particle diameter of the thermoplastic resin powder is preferably 0.01 to 200 μm, more preferably 0.01 to 100 μm, from the viewpoint of controlling the thickness of the sheet.

  The ratio of the liquid or solid curable composition and the thermoplastic resin powder used in producing the gel curable resin sheet varies depending on the type of the curable composition used and the type of the thermoplastic resin powder. Therefore, although it cannot be defined uniquely, generally it is preferably 10 to 100 parts, more preferably 20 to 70 parts of thermoplastic resin powder with respect to 100 parts of epoxy resin. If the amount of the thermoplastic resin powder is too small, the sheet strength tends to decrease when the sheet is formed, and if it is too large, the fluidity is low, high pressure is required during hot roll, and chip breakage occurs. It becomes easy.

  A liquid or solid curable composition and thermoplastic resin powder as described above are blended and held, and the curable composition is absorbed into the thermoplastic resin powder, or the curable composition and the thermoplastic resin powder are compatible. By making it, a gel-like curable composition can be obtained.

  The above blending and holding may be performed with stirring or non-stirring after uniformly mixing at room temperature or under heating. For example, it is performed by mixing at about 25 ° C. with a kneader.

  In order to promote absorption of the curable composition into the thermoplastic resin powder or compatibility between the curable composition and the thermoplastic resin powder, heating is preferably performed. At this time, it is preferable that the curable composition is applied by, for example, a roll coater, and then heated for gelation. In this case, the heating temperature is equal to or higher than the glass transition temperature of the thermoplastic resin powder, preferably higher than the softening temperature, lower than the melting start temperature of the thermoplastic resin powder, the active temperature of the curing agent and / or latent curing accelerator used. The following temperature is preferred. Usually, the temperature is preferably 5 to 50 ° C., more preferably 10 to 30 ° C. higher than the softening temperature of the thermoplastic resin powder, and the temperature is lower than the active temperature of the curing agent and / or the latent curing accelerator used. Is preferred. The heating time is sufficient if the curable composition is absorbed in the thermoplastic resin powder or the curable composition and the thermoplastic resin powder are compatible and a gelled curable composition is obtained. Good. The heating temperature is usually 60 to 150 ° C., more preferably 80 to 120 ° C., and the heating time is 0.5 to 30 minutes, further 1 to 10 minutes. (The surface acoustic wave chip can be protected by a protective layer formed from a gel-like curable resin sheet by a subsequent heat roll).

  The gel-like curable composition thus obtained can be formed into a sheet by a usual method such as thermoforming. In addition, the liquid or solid curable composition and the thermoplastic resin powder before becoming a gel-like curable composition were blended, and the film thickness was controlled by a roll coater or the like when heated to be a liquid. It can be made into a sheet by drying it at 60 to 150 ° C. for 0.5 to 30 minutes, and further at 80 to 120 ° C. for 1 to 10 minutes. When a sheet is formed by these methods, a sheet having a thickness of about 50 μm to a thickness of 1000 μm can be manufactured because of the solventless system. If a solvent-based material is used, only a material having a thickness of about 100 μm can be produced.

  The thickness of the formed gel-like curable resin sheet used in the present invention is such that a sealing resin layer is formed by covering a functional element connected by a bump on the wiring board, for example, a surface acoustic wave chip, and performing heat rolling. In view of the fact that the surface of the sealing resin can be made flat, preferably at least twice the sum of the distance between the wiring board and the functional element and the thickness of the functional element. It is preferable that the thickness is not more than twice, more preferably not more than 1.5 times. As the actual thickness of the gel-like curable resin sheet, since the thickness of the surface acoustic wave chip is generally 200 to 400 μm and the height of the bump is generally 20 to 80 μm, 220 to 960 μm, and further 220 to 720 μm. Is preferred.

  In the above description, as the gel-like curable resin sheet, a sheet of a mixture of a liquid or solid curable composition and a thermoplastic resin powder that acts as a gelling agent is used. You may use what was made into a sheet | seat using the mixture of the photopolymerizable compound which acts as a gelatinizer, and a radical generating agent. In this case, first, a mixture of a liquid or solid curable composition, a photopolymerizable compound and a radical generator is prepared, and the resulting mixture is made into a sheet and then irradiated with light to produce photopolymerizable. A polymerized compound is used as a gel-like curable resin sheet.

  Examples of the photopolymerizable compound include one or more (meth) acryloyl group-containing compounds in the molecule, for example, esters of (meth) acrylic acid with alkyl alcohols, alkylene diols, polyhydric alcohols, and the like. Examples thereof include compounds described in [0009] to [0012] of Japanese Patent No. 12543.

  Examples of the radical generator include compounds that generate radicals upon irradiation with active rays such as ultraviolet rays and electron beams. For example, 2-hydroxy-2-methyl- 1-phenylpropan-1-one, benzoin, acetophenone, and the like can be used.

  The amount of the radical generator used is preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, per 100 parts of the photopolymerizable compound.

  The usage ratio of the liquid or solid curable composition and the photopolymerizable compound and radical generator acting as a gelling agent is as follows: 100 parts of the curable composition are the photopolymerizable compound and radical generator. The total amount is preferably 5 to 100 parts, more preferably 10 to 30 parts.

  The thickness of the gel-like curable resin sheet used in the present invention formed using the photopolymerizable compound and the radical generator is the gel-like curable resin formed using the thermoplastic resin powder. It may be the same as the thickness of the sheet.

The gel-like curable resin sheet preferably has a low glass transition temperature and a low coefficient of linear expansion because the cured product can be reduced in stress (lowered in warpage), and further purified from a raw material. It is preferable that the number of impurity ions is small and contamination of the surface acoustic wave chip surface can be prevented. Further, the elastic modulus (25 ° C.) of the gel-like curable resin sheet is 10 ³ to 10 ⁹ Pa, It is 10 ⁴ to 10 ⁸ Pa, and the melt viscosity at the time of curing is 10 to 10 ⁵ Pa · s, more preferably 10 ³ to 10 ⁴ Pa · s, so that it can be heated and rolled before the sealing resin layer is formed. It is preferable for forming a sealing resin layer so that a portion where the surface of the surface acoustic wave electrode and the surface on which the wiring pattern is formed is separated from the device by the height of the bump maintains a hollow structure. The softening temperature is 50 ° C. or higher, preferably 60 ° C. or higher, more preferably 80 ° C. or higher.

  As described above, the gel-like curable resin sheet has a low glass transition temperature and / or a low coefficient of linear expansion in reducing the stress of the cured product (lowering warpage). preferable. As low glass transition temperature, Tg of the hardened | cured material of a gel-like curable resin sheet is 100 degrees C or less, More preferably, it is 60 degrees C or less. In order to obtain a low coefficient of thermal expansion in order to reduce warpage, adjust fluidity, increase the reliability of electronic components, etc., the gel-like curable resin sheet preferably contains 50% by weight or more of an inorganic filler (for example, fused silica). More preferably, it is 75% by weight or more, and more preferably 80% by weight or more. In the case of a sheet highly filled with a filler, the coefficient of thermal expansion becomes low and the warpage can be reduced. Therefore, considering the reliability, a higher Tg is preferable, for example, preferably 100 ° C. or higher, more preferably 150 ° C. or higher. However, the present invention is not limited to this, and can be adjusted according to the application.

  In the above description, it is assumed that one gel-like curable resin sheet is used. However, in the present invention, a plurality of the gel-like curable resin sheets, for example, 2 to 20 sheets are used. Also good. In the case of using a laminate of two or more sheets, it is possible to cope with chips having different thicknesses with a small number of gel-like curable sheets. Further, if the softening temperature of the innermost layer sheet that is in direct contact with the chip is set higher than that of the other sheets, the effect of preventing the resin from entering under the chip when a hot roll is applied can be enhanced. As a gel-like curable resin sheet when using a plurality of sheets, a sheet having a thickness of 1/20 times or more and 1 time or less of the sum of the distance between the wiring board and the functional element and the thickness of the functional element Is preferably used by laminating a plurality of sheets having a thickness not more than twice the above sum.

  In the case where the softening temperature of the innermost layer sheet is higher than that of other sheets, the softening temperature is preferably higher by 5 ° C or more, more preferably higher by 10 ° C or more, because of the manufacturing method. . Here, the softening temperature is defined as a temperature at which the sealing property is not impaired, that is, a temperature at which the viscosity of the sheet is sufficiently lowered, from the viewpoint of sealing the electronic component while softening the sheet by heating, For example, it can be measured by a method for obtaining the intersection of extrapolated lines from a graph of the temperature change of the elastic modulus G ′. The temperature at the intersection of the tangent line and the tangent line drawn in the region where G ′ is sufficiently lowered can be obtained. Moreover, as a method of laminating a plurality of the gel-like curable resin sheets, a laminating method is preferable. For example, as a method of laminating two or more sheets, a laminator provided with two rollers that can be heated can be used. The laminating temperature is preferably 25 to 120 ° C. because the sheet can be reliably laminated without change in the softening point and viscosity of the sheet.

  In the present invention, in addition to the one or more gel-like curable resin sheets, an additional resin sheet other than the gel-like curable resin sheet may be laminated as necessary. it can. The other resin sheet is, for example, a low moisture-permeable thermoplastic resin-based sheet (for example, a polyester-based or polyolefin-based sheet), a curable resin sheet (for example, a moisture-permeable and fluidity-suppressed material by blending an inorganic filler) A material having a desired special function such as an epoxy resin-based curable sheet or a polyimide-based resin sheet can be used. The additional resin sheet is preferably laminated under the curable resin sheet in order not to cause trouble when the curable resin is flowed with a hot roll, but is not necessarily limited thereto. .

Step (b)
In this step, a closed space region surrounded by the gel-like curable resin sheet containing the plurality of arranged functional elements and the wiring board is evacuated. In order to make the closed space region into a vacuum, for example, the step (a) may be performed in a vacuum to achieve the vacuum in the closed space region. In order to perform the step (a) in a vacuum, for example, a temperature at which the resin sheet is tacked in advance by using a device capable of forming a vacuum compartment such as a vacuum press, for example, a tackiness, At about 50 ° C., the resin sheet is brought into close contact with the substrate by low-pressure pressing. In addition, the degree of vacuum may be a degree of vacuum normally achieved by a vacuum press or the like, and may be, for example, 1.0 to 0.01 Toor. In order to form the vacuum compartment, for example, a vacuum chamber, a movable vacuum frame, or the like can be used.

Furthermore, after performing the said process (a) under atmospheric pressure, before the said process (c), or performing the said process (a) under atmospheric pressure, the said gel-like curable resin sheet And vacuum lamination may be performed by sucking air from the closed space region surrounded by the wiring board and the wiring board to achieve a vacuum in the closed space region. In order to perform the above vacuum lamination, for example, a laminator may be used to exhaust air while uniformly pressurizing at atmospheric pressure through a partition rubber sheet, and if applicable, it is exhausted from a hole provided in the substrate. May be.
In the present invention, the method for achieving the vacuum in the closed space region is not limited at all, and any possible method can be adopted, and the method described here is merely an example. Moreover, the said process (a) and the process (b) may be operated integrally as mentioned above, or may be operated individually.

Step (c)
In this step, the surface of the sealing resin is formed flat while heating and flowing the gel-like curable resin sheet below the curing temperature with a hot roll while maintaining the closed space region in a vacuum. To perform this, for example, if the step (a) is performed in a vacuum, the step (b) is also integrally operated by achieving a vacuum in the closed space region, and As it is, the process (c) is performed in a vacuum, or the process (b) is also integrally operated, and then the system is once released from the vacuum, but the vacuum in the closed space region is maintained. Step (c) may be performed. In the latter case, it is possible to maintain the closed space region by utilizing the tackiness of the gel-like curable resin sheet. Alternatively, this step is performed after the step (a) and the step (b) are separately operated. In general, a method in which this step is performed at atmospheric pressure is preferable because an operation of applying a hot roll is easy.

  The heat roll is preferably performed at a temperature of not less than the softening point of the gel-like curable resin sheet and less than the curing temperature, preferably 60 to 250 ° C, more preferably 60 to 180 ° C, and more preferably 80 to 120 ° C. Is more preferable. If the heat roll temperature is lower than the softening point of the gel-like curable resin sheet, the fluidity is insufficient, the sealing resin is not filled, and the chip is easily damaged. It becomes easy to cause foaming when the resin is cured.

  When two upper and lower rolls are used as the heat roll, the heat roll is preferably composed of a high temperature first roll in contact with the resin and a low temperature second roll in contact with the wiring board. The high-temperature hot roll is set to be higher than the softening point of the sealing resin and lower than the curing temperature, and the low-temperature roll is set to be lower than the softening point of the sealing resin, for example, room temperature (25 ° C.). As a result, the surface side of the sealing resin becomes higher temperature, the fluidity is increased and the moldability is improved, the temperature is lowered on the wiring board side, the resin fluidity is lowered, and the inflow under the chip can be further suppressed. it can. Moreover, it can also be set as 1 roll structure as said heat roll. In this case, the molding is performed by placing a hot roll on the gel-like curable resin sheet after placing the wiring board to be sealed on a support base. Also in this case, since the support base is at room temperature, the temperature becomes low on the wiring board side, and the fluidity of the resin is lowered, so that the inflow under the chip can be further suppressed.

  It is preferable to keep the gap of the roll constant in order to form the sealing resin surface flatly, and in particular, it is preferable to maintain the product thickness, for example, 1.2 mm or less. Further, it is preferable to use a rubber roll as the roll on the sealing resin side, because even if the resin sheet has irregularities, it can be pressurized uniformly. The speed at which the roll is applied can be about 0.1 to 0.3 m / min.

Step (d)
In this step, the gel-like curable resin sheet is heated to the curing temperature and cured. The heat curing method is not particularly limited, and can be performed by heating in an oven or the like, for example.

  A surface acoustic wave chip is mounted on a substrate on which a wiring pattern is formed, and the surface of the substrate on which the wiring pattern is formed and the electrode surface on which the surface acoustic wave electrode of the surface acoustic wave chip is formed face each other The surface acoustic wave electrode and the wiring pattern are connected by a bump, and the surface of the surface acoustic wave electrode and the surface on which the wiring pattern is formed are separated from each other by the height of the bump. A protective layer formed from a gel-like curable resin sheet from the surface opposite to the electrode surface of the surface wave chip to the surface of the substrate. The surface where the surface acoustic wave electrode surface and the wiring pattern are formed has a bump height. In the case of manufacturing a surface acoustic wave device in which the separated portions are covered so as to maintain a hollow structure, it can be performed, for example, as follows according to the present invention. That is, first, the gel-like curable resin sheet is attached to the substrate on which the surface acoustic wave chip is mounted so that the portion covered with the gel-like curable resin sheet is kept under vacuum, and then the elastic The surface of the protective layer is shaped to be substantially flat by flowing the resin using a hot roll so as to maintain a hollow structure between the surface wave chip and the substrate.

  The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Examples 1-5 and Comparative Examples 1-2
A varnish was prepared with the composition shown in Table 1, and this varnish was applied to a release-treated surface of a 75 μm-thick PET film that had been subjected to a release treatment, and after drying, the resin layer was adjusted to a thickness of 300 μm. A gel-like epoxy resin sheet (softening point 50 ° C.) was formed on the PET film.

The obtained sheet was measured for softening temperature (° C.), elastic modulus at the time of softening (Pa), and dynamic complex viscosity at the time of softening (Pa · s). Moreover, Tg (degreeC) of the hardened | cured material (150 degreeC, 3 hours, oven hardening), a linear expansion coefficient (ppm), and a bending elastic modulus (25 degreeC, 150 degreeC; GPa) were measured.
Measuring method:
Softening temperature, elastic modulus, viscosity: ARES viscoelasticity measuring device (TA), dynamic viscoelasticity measurement (Temp Ramp, frequency 1HZ, Ramp Rate 2.5 ° C / min)
Flexural modulus: DMA6100 (SEIKO), dynamic viscoelasticity measurement (Temp Ramp, frequency 1 Hz, Ramp Rate 2 ° C./min)
Linear expansion coefficient: TMA120C (SEIKO), (Ramp Rate 2.5 ° C./min)

  The obtained sheet was cut into an appropriate size, and a dummy chip of 400 μm × 2 mm × 2 mm connected to a 200 μm × 30 mm × 50 mm glass epoxy substrate by a bump of 50 μm in height is 2 mm in 7 rows and 7 columns. On the device before forming the protective layer formed at 49 intervals, the device was placed so as to cover the outermost array of chips up to 2 mm. This was used for Examples and Comparative Examples.

  In Example 1, the sheet obtained by Formulation 1 was vacuum-laminated on the device with a vacuum laminator (25 ° C., 5 seconds, sheet outer periphery attached to substrate using sheet tack). In Example 2, the device obtained by placing the sheet obtained in Formulation 1 was preformed by vacuum pressing at 0.1 MPa at 50 ° C. for 10 seconds. In each of the comparative examples, the sheet obtained by blending 1 was placed on a device and directly subjected to a hot press or a hot roll. In both Examples and Comparative Examples, the heat roll was set at 0.77 mm between the upper roll (100 ° C., rubber roll) and the lower roll (25 ° C., metal roll), and was performed at a speed of 0.3 m / min. Thereafter, each sample was oven cured at 150 ° C. for 3 hours. Moreover, the hot press of the comparative example was cured at 150 ° C. for 5 minutes at 0.1 MPa.

  In Examples 3 to 5, Formulation 2 and Formulation 3 (Example 3), Formulation 2 and Formulation 4 (Example 4), or Formulation 3 and Formulation 4 (Example 5) are laminated one by one. did. As a method of laminating two sheets in Examples 3 to 5, a laminator (manufactured in-house) equipped with two heatable rollers was used. The laminating temperature was 100 ° C.

The abbreviations in Table 1 are as follows.
LSAC6006: manufactured by Asahi Kasei Epoxy Corporation, modified (propylene oxide addition) epoxy resin, epoxy equivalent 250 g / eq
DAL-BPFD: Honshu Chemical Industry Co., Ltd., diallyl bisphenol F
HX3088: manufactured by Asahi Kasei Epoxy Co., Ltd., modified imidazole, active temperature about 80 ° C.
F301: manufactured by Nippon Zeon Co., Ltd., acrylic powder, particle size 2 μm, softening temperature 80-100 ° C. polymethyl methacrylate FB201S: manufactured by Denki Kagaku Kogyo Co., Ltd., filling silica A187: manufactured by Nippon Unicar Co., Ltd., epoxy silane IXE600: manufactured by Toagosei Co., Ltd., bismuth antimony, ion catcher RY200: manufactured by Nippon Aerosil Co., Ltd., fine silica, thixotropic agent RE304S: manufactured by Nippon Kayaku Co., Ltd., bisphenol F type epoxy resin, epoxy equivalent 170 g / eq
ELM100: manufactured by Sumitomo Chemical Co., Ltd., amino epoxy resin, epoxy equivalent of 105 g / eq
EPPN-502H: Nippon Kayaku Co., Ltd., polyfunctional epoxy resin, epoxy equivalent 170 g / eq
MEH7500: Meiwa Kasei Co., Ltd., polyfunctional phenol, phenol equivalent 105g / eq
2P4MHZ: Shikoku Kasei Kogyo Co., Ltd., modified imidazole

Evaluation method Intrusion of resin under the chip: The substrate of the resin-encapsulated device (dummy device) (dummy device) after the hot roll process and the chip are forcibly separated, and the presence or absence of the resin intrusion into the lower part of the chip is observed with a microscope. Evaluation was made according to the following criteria.
A: The resin penetration from the chip end is 10 μm or less. ○: The resin penetration from the chip end is 20 μm or less. X: The resin penetration from the chip end exceeds 20 μm.
Void: The substrate and chip of the resin-encapsulated device (dummy device) (manufactured) after the hot roll process were forcibly peeled, and the presence or absence of voids at the end of the chip was observed with a microscope and evaluated according to the following criteria.
Little void: Void from tip end is 50 μm or less Void on outer periphery: Void from tip end exceeds 50 μm.
State after curing: The resin-encapsulated device after the hot roll process is cured in an oven, the substrate and chip are forcibly separated, and the presence or absence of resin intrusion into the lower part of the chip and voids are observed with a microscope. It was evaluated with.
Good: Intrusion and void change were small compared to after hot roll. Void: Air under the chip expanded and voids were generated.
The results are shown in Table 2.

  From the above Examples 1-2, according to the manufacturing method of the present invention, sealing under the resin under the chip does not enter and the voids are reduced, and from Example 3-5, the resin under the chip is obtained by laminating a plurality of sheets. It was shown that the penetration was better and the drawbacks of Comparative Examples 1 and 2 corresponding to the conventional method could be overcome. In addition, the air expansion | swelling was large compared with the case of the hot press (comparative example 1) in the state after hardening of the comparative example 2.

INDUSTRIAL APPLICABILITY The present invention overcomes the disadvantages of the conventional hollow mold electronic component manufacturing method, enables manufacturing with a higher yield, and is extremely useful as a method for manufacturing an electronic component using a gel-like curable resin sheet.

Claims (15)

A plurality of arrayed functional elements placed facing each other with a space between the wiring board and the wiring board are arranged on the wiring board so as to cover the plurality of arrayed functional elements. A method of manufacturing an electronic component that heat-cures a state-curable resin sheet and keeps a space between the wiring board and the functional element while encapsulating the resin together, and includes at least the following step (a), An electronic component manufacturing method comprising (b), (c) and (d):
(A) a step of disposing a gel-like curable resin sheet on the wiring board so as to cover the plurality of arranged functional elements placed facing each other with a gap provided between the wiring board and the wiring board;
(B) a step of evacuating a closed space region surrounded by the gel-like curable resin sheet and the wiring board in which the plurality of arranged functional elements are included;
(C) The step of forming the sealing resin surface flat while heating and flowing the gel-like curable resin sheet below the curing temperature with a hot roll while maintaining the closed space region in a vacuum, and
(D) A step of curing the gel-like curable resin sheet by heating to a curing temperature. The manufacturing method according to claim 1, wherein after the step (b) is achieved by performing the step (a) in a vacuum, the step (c) is performed after releasing the vacuum. The manufacturing method according to claim 1, wherein the step (b) is achieved by performing the step (a) in a vacuum, and the step (c) is performed in the vacuum without being released from the vacuum. The method according to claim 2 or 3, wherein the step (a) is performed by a vacuum press, and the step (b) is achieved by disposing a gel-like curable resin sheet on the wiring board in a vacuum. After performing the step (a) under atmospheric pressure and before the step (c), or while performing the step (a) under atmospheric pressure, the gel-like curable resin sheet and the wiring The manufacturing method according to claim 1, wherein the step (b) is achieved by sucking air from a closed space region surrounded by the substrate. The manufacturing method according to any one of claims 1 to 5, wherein the heat roll includes a high-temperature first roll in contact with the resin and a low-temperature second roll in contact with the wiring board. The method according to any one of claims 1 to 5, wherein the forming is performed by placing a heat roll on the gel-like curable resin sheet after placing the wiring substrate to be sealed on a support base. The said gel-like curable resin sheet is a gel-like epoxy resin sheet, The manufacturing method in any one of Claims 1-7. 2. The gel-like curable resin sheet is a single sheet having a thickness of 1 to 2 times the sum of the distance between the wiring board and the functional element and the thickness of the functional element. The manufacturing method in any one of -8. As the gel-like curable resin sheet, a sheet having a thickness of 1/20 times or more and 1 time or less of the sum of the distance between the wiring board and the functional element and the thickness of the functional element is 2 of the sum. The manufacturing method according to claim 1, wherein a plurality of sheets having a thickness of twice or less are laminated and used. The manufacturing method according to claim 10, wherein the innermost layer of the plurality of sheets has a softening temperature higher than that of the other sheets. The manufacturing method according to any one of claims 8 to 11, wherein in addition to the one or more gel-like curable resin sheets, an additional resin sheet other than the gel-like curable resin sheet is laminated. The manufacturing method according to claim 12, wherein the other resin sheet is a low moisture permeability thermoplastic resin sheet. The manufacturing method according to claim 1, wherein the functional element is a surface acoustic wave device. In the surface acoustic wave device, an electrode surface on which a surface acoustic wave electrode of a surface acoustic wave chip is formed and the wiring substrate are arranged facing each other, and the electrode and a wiring pattern on the wiring substrate are connected by a bump. The chip and the wiring board are separated by the height of the bump, and the electrode surface and the wiring board are sealed with resin in a hollow state. The manufacturing method as described.