JP7160794B2 - Mounting structure manufacturing method and sheet material used therefor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a mounting structure, and more particularly to a method for manufacturing a sealed mounting structure and a sheet material used for sealing a mounting member.

Some electronic components (circuit members) mounted on a circuit board require a space between them and the circuit board. For example, a SAW chip used for noise reduction in mobile phones uses surface waves propagating on a piezoelectric substrate (piezoelectric body) to filter a desired frequency. A space is required between the circuit board to be connected. When sealing such a mounting member having a space inside (internal space), a sheet-like sealing material (hereinafter referred to as sheet material) is sometimes used.

The sealing material is required to have low moisture permeability. This is because if moisture adheres to the circuit member, it may cause a short circuit or corrosion. Further, the encapsulant is required to generate a small amount of ionic impurities when exposed to high temperature and/or high humidity. This is because ionic impurities can cause migration of the metal used in the mounting structure. In the case of a mounting member having an internal space as described above, ionic impurities derived from the sealing material tend to remain in the internal space. Therefore, it is particularly required to suppress the generation of ionic impurities. US Pat. No. 5,300,009 teaches a sheet material that extracts low amounts of ionic impurities under certain conditions.

In Patent Document 1, ionic impurities are added to a sheet material under conditions according to the pressure cooker test (PCT) developed for the purpose of evaluating the moisture resistance of a resin-sealed mounting structure. dissolution tests have been carried out.

JP 2014-209563 A

In recent years, a high-temperature, high-humidity bias test is often used as a moisture resistance test for mounting structures. In this test, a constant bias voltage is applied to the sample under high temperature and high humidity conditions, enabling evaluation assuming use in an actual machine. Therefore, problems due to elution of ionic impurities are more likely to occur than with PCT. As in Patent Document 1, when a total amount of ions of 10 ppm or more is eluted from the sheet material into water under conditions conforming to PCT, under the conditions of the high-temperature and high-humidity bias test, insulation failure may occur, and the mounting structure may be damaged. Failure due to corrosion or the like is likely to occur. In particular, chloride ions, sodium ions, potassium ions, etc. are likely to cause corrosion, and it is important to control the total amount of these. In recent years, circuit members tend to be mounted at high density, and migration and corrosion as described above are particularly likely to occur. Therefore, it is important to reduce ionic impurities derived from the sealing material.

In view of the above, one aspect of the present invention includes a first circuit member and a plurality of second circuit members mounted on the first circuit member, and the first circuit member and the second circuit member preparing a mounting member having a space formed therebetween; preparing a sheet material containing a thermosetting resin, a curing agent, a thermoplastic resin, and an inorganic filler; and facing the second circuit member placing the sheet material on the mounting member; pressing the sheet material against the first circuit member; heating the sheet material to maintain the space; and a sealing step of sealing a circuit member, wherein the total amount of chloride ions, sodium ions, and potassium ions contained in the thermoplastic resin is 30 ppm or less on a mass basis. related to the manufacturing method of

Another aspect of the present invention is a sheet material containing a thermosetting resin, a curing agent, a thermoplastic resin, and an inorganic filler, wherein chloride ions contained in the thermoplastic resin, The sheet material has a total content of sodium ions and potassium ions of 30 ppm or less on a mass basis.

According to the present invention, since the mounting structure is sealed using a sheet material containing an extremely small amount of chloride ions, sodium ions, and potassium ions contained in the thermoplastic resin, an environment such as a high-temperature, high-humidity bias test is possible. Even at the bottom, generation of ionic impurities from the sheet material is suppressed. Therefore, a highly reliable mounting structure can be obtained.

1 is a cross-sectional view schematically showing a mounting structure according to one embodiment of the present invention; FIG. It is explanatory drawing which shows typically the manufacturing method concerning one Embodiment of this invention by the cross section of a mounting member or a mounting structure.

An example of a mounting structure manufactured by the method according to this embodiment is shown in FIG. FIG. 1 is a cross-sectional view schematically showing a mounting structure 10. As shown in FIG.
The mounting structure 10 includes a first circuit member 1, a plurality of second circuit members 2 mounted on the first circuit member 1 via bumps 3, for example, and a sealing material for sealing the second circuit members 2. 4 and . A space (internal space S) is formed between the first circuit member 1 and the second circuit member 2 .

The sealing material 4 is a cured sheet material. The present invention includes this sheet material. The sheet material contains a thermosetting resin, a curing agent, a thermoplastic resin, and an inorganic filler.

The sheet material contains a thermoplastic resin as a sheeting agent (for example, a pregelling agent). When thermoplastic resins are exposed to high temperatures and/or high humidity, they tend to generate ionic impurities because of their structure compared to other raw materials (especially thermosetting resins). Therefore, in order to reduce ionic impurities generated from a sheet material containing a thermoplastic resin as a raw material, ions of causative elements (for example, elements with a high ionization tendency) contained in the thermoplastic resin that can be generated as ionic impurities (hereinafter referred to as causative ions) is important to control.

At this time, it is desirable to control the absolute amount of causative ions contained in the thermoplastic resin rather than the amount of causative ions that can be eluted from the thermoplastic resin into water (hereinafter referred to as the amount of eluted ions). For example, conventionally, an attempt has been made to incorporate an ion catcher into a sheet material to capture eluted ions. However, it is difficult to suppress ionic impurities to the level of this embodiment by trapping eluted ions with an ion catcher. Also, the eluted ions captured by the ion catcher may be released again. Furthermore, in this method, it is necessary to blend a plurality of types of ion catchers corresponding to the polarities and types of causative ions. Therefore, the production of the sheet material may become complicated, or the function of the sheet material may be impaired. However, this embodiment does not limit the use of ion catchers.

In the present embodiment, sodium ions (Na ions), potassium ions (K ions) and chloride ions (Cl ions), which are contained in the catalyst etc. used when synthesizing the thermoplastic resin and tend to remain in the thermoplastic resin, Focusing on , a thermoplastic resin in which the absolute amount of these causative ions is reduced to an extremely low level is used. As a result, problems such as migration and corrosion due to generation of ionic impurities from the sheet material can be suppressed even in an environment such as a high-temperature, high-humidity bias test. In particular, when the mounting structure has an electrode containing aluminum, migration and corrosion are easily suppressed by reducing the absolute amount of Cl ions. By reducing the absolute amount of causative ions contained in the thermoplastic resin, the amount of eluted ions eluted from the sheet material is dramatically reduced.

[Sheet material]
The sheet material is a member that seals the second circuit member 2, and is made of a thermosetting resin composition containing a thermosetting resin, a curing agent, a thermoplastic resin, and an inorganic filler.

The thermosetting resin before sealing may be in an uncured state or in a semi-cured state. A semi-cured state is a state in which the thermosetting resin contains monomers and/or oligomers, and the state in which the three-dimensional crosslinked structure of the thermosetting resin is insufficiently developed. A semi-cured thermosetting resin does not dissolve in a solvent at room temperature (25° C.), but is incompletely cured, ie, in the so-called B stage.

Thermosetting resins include, but are not limited to, epoxy resins, (meth)acrylic resins, phenolic resins, melamine resins, silicone resins, urea resins, urethane resins, vinyl ester resins, unsaturated polyester resins, diallyl phthalate resins, and polyimides. A resin etc. are mentioned. These may be used individually by 1 type, and may be used in combination of 2 or more type. Among them, epoxy resin is preferable.

Although the epoxy resin is not particularly limited, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, naphthalene. type epoxy resins, alicyclic-aliphatic epoxy resins, glycidyl ethers of organic carboxylic acids, and the like can be used. These may be used alone or in combination of two or more. The epoxy resin may be a prepolymer or a copolymer of an epoxy resin such as a polyether-modified epoxy resin or a silicone-modified epoxy resin and another polymer. Among them, bisphenol AD type epoxy resin, naphthalene type epoxy resin, hydrogenated bisphenol A type epoxy resin and/or bisphenol F type epoxy resin are preferable. Hydrogenated bisphenol A type epoxy resins and bisphenol F type epoxy resins are particularly preferable because they are excellent in heat resistance and water resistance and inexpensive.

In order to adjust the viscosity of the resin composition, the epoxy resin may contain a monofunctional epoxy resin having one epoxy group in the molecule in an amount of about 0.1 to 30% by mass based on the total epoxy resin. As such a monofunctional epoxy resin, phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, ethyldiethylene glycol glycidyl ether, dicyclopentadiene glycidyl ether, 2-hydroxyethyl glycidyl ether and the like can be used. These may be used alone or in combination of two or more.

The total absolute amount of Na ions, K ions and Cl ions contained in the epoxy resin (total absolute amount) is preferably 300 ppm or less, more preferably 250 ppm or less. If the total absolute amount contained in the epoxy resin is within this range, even under an environment such as a high-temperature, high-humidity bias test, migration and corrosion due to ionic impurities originating from the sheet material can be easily suppressed. The absolute amount is calculated on a mass basis (hereinafter the same).

The thermosetting resin composition contains a thermosetting resin curing agent. The curing agent is not particularly limited, but for example, a phenol-based curing agent (phenol resin, etc.), a dicyandiamide-based curing agent (dicyandiamide, etc.), a urea-based curing agent, an organic acid hydrazide-based curing agent, a polyamine salt-based curing agent, an amine adduct. A curing agent, an acid anhydride curing agent, an imidazole curing agent, or the like can be used. These may be used alone or in combination of two or more. The type of curing agent is appropriately selected according to the thermosetting resin. Among them, it is preferable to use a phenol-based curing agent from the viewpoint of low outgassing during curing, moisture resistance, heat cycle resistance, and the like.

The amount of curing agent varies depending on the type of curing agent. When an epoxy resin is used, for example, it is possible to use an amount of the curing agent such that the number of equivalents of the functional group of the curing agent is 0.001 to 2 equivalents, further 0.005 to 1.5 equivalents, per equivalent of the epoxy group. preferable.

The dicyandiamide-based curing agent, urea-based curing agent, organic acid hydrazide-based curing agent, polyamine salt-based curing agent, and amine adduct-based curing agent are latent curing agents. The activation temperature of the latent curing agent is preferably 60°C or higher, more preferably 80°C or higher. Also, the activation temperature is preferably 250° C. or lower, more preferably 180° C. or lower. This makes it possible to obtain a thermosetting resin composition that cures rapidly at the activation temperature or higher.

The thermosetting resin composition contains a thermoplastic resin with a small absolute amount of causative ions (hereinafter referred to as a high-purity thermoplastic resin). A high-purity thermoplastic resin is compounded as a sheeting agent. By forming the thermosetting resin composition into a sheet, the handleability in the sealing process is improved, and dripping of the thermosetting resin composition is suppressed, and the internal space S is easily maintained.

The high-purity thermoplastic resin is not particularly limited as long as the absolute amount of causative ions is small. Types of high-purity thermoplastic resins include, for example, acrylic resins, polyolefins, polyurethanes, blocked isocyanates, polyethers, polyesters, polyimides, polyvinyl alcohols, butyral resins, polyamides, vinyl chloride, cellulose, thermoplastic epoxy resins, thermoplastic phenols. A resin etc. are mentioned. Among these resins, acrylic resins are preferable because they are excellent in function as a sheeting agent, and the absolute amount of causative ions can be easily reduced in terms of the synthesis method. The amount of the high-purity thermoplastic resin is preferably 5 to 200 parts by mass, particularly preferably 10 to 100 parts by mass, per 100 parts by mass of the thermosetting resin.

The form of the high-purity thermoplastic resin when added to the thermosetting resin composition is not particularly limited. The high-purity thermoplastic resin may be, for example, particles with a weight average particle size of 0.01 to 200 μm, preferably 0.01 to 100 μm. The particles may have a core-shell structure. In this case, the core may be, for example, a polymer containing units derived from at least one monomer selected from the group consisting of n-, i- and t-butyl (meth)acrylate, or other (meta ) It may be a polymer containing an acrylate-derived unit. The shell layer comprises, for example, monofunctional monomers such as methyl (meth)acrylate, n-, i- or t-butyl (meth)acrylate, (meth)acrylic acid, and multifunctional monomers such as 1,6-hexanediol diacrylate. It may be a copolymer with. A high-purity thermoplastic resin dispersed or dissolved in a solvent may also be added to the thermosetting resin composition.

The total absolute amount (total absolute amount) of Na ions, K ions and Cl ions contained in the high-purity thermoplastic resin is 30 ppm or less. Therefore, even in an environment such as a high-temperature, high-humidity bias test, the occurrence of migration and corrosion due to ionic impurities originating from the sheet material is extremely reduced. The total absolute amount is preferably 20 ppm or less, more preferably 15 ppm or less.

In particular, the absolute amount of Cl ions contained in the high-purity thermoplastic resin is preferably 15 ppm or less, more preferably 8 ppm or less. The absolute amount of Na ions contained in the high-purity thermoplastic resin is preferably 10 ppm or less, more preferably 5 ppm or less. The absolute amount of K ions contained in the high-purity thermoplastic resin is preferably 5 ppm or less, more preferably 2 ppm or less. In particular, when the absolute amount of Cl ions contained in the high-purity thermoplastic resin is within this range, migration and corrosion are more likely to be suppressed when the mounting structure has electrodes containing aluminum.

The absolute amount of each causative ion can be quantified by the following method.
Cl ions can be quantified, for example, by combustion ion chromatography. In the combustion ion chromatography method, a high-purity thermoplastic resin is combusted using a combustion decomposer or the like, and combustion gas is held or absorbed in an absorption liquid. Cl ions can be quantified by ion chromatographic analysis of this absorption liquid. The combustion temperature is, for example, 900-1000°C. As the absorption liquid, for example, ion-exchanged water added with bromine (Br) as an internal standard substance is used.

Na and K ions can be quantified by inductively coupled plasma (ICP) emission spectroscopy. Prior to the ICP emission spectroscopic analysis, a high-purity thermoplastic resin may be subjected to pretreatment such as ashing and dissolved in hydrochloric acid as a sample. The incineration method is not particularly limited, and may be a dry method or a wet method. Among them, the dry method is preferable because it is a simple method. The heating temperature in the dry method is not particularly limited, and is, for example, about 500.degree.

When the absolute amount is extremely small, the amount of eluted ions (eluted ion concentration) is also reduced. For example, when 100 g of a high-purity thermoplastic resin (in the case of particles, resin particles having a 100-mesh pass (average particle diameter of 150 μm or less)) is immersed in 1000 g of ion-exchanged water at 121° C. at 2 atmospheres for 20 hours, the above The total elution ion concentration (total elution ion concentration) of Cl ions, Na ions and K ions contained in ion-exchanged water can be 20 ppm or less. The total eluted ion concentration is preferably 10 ppm or less. If the total amount of eluted ions in the high-purity thermoplastic resin is within this range, migration and corrosion due to ionic impurities originating from the sheet material can be easily suppressed even in an environment such as a high-temperature, high-humidity bias test. The average particle size is the particle size (D50; hereinafter the same) at 50% of the cumulative volume in the volume particle size distribution. Note that the eluted ion concentration is calculated on a mass basis (hereinafter the same).

In particular, the eluted ion concentration of Na ions in the high-purity thermoplastic resin is preferably 10 ppm or less, more preferably 5 ppm or less. The eluted ion concentration of K ions in the high-purity thermoplastic resin is preferably 5 ppm or less, more preferably 2 ppm or less. The eluted ion concentration of Cl ions in the high-purity thermoplastic resin is preferably 10 ppm or less, more preferably 5 ppm or less.

Here, the concentration of eluted ions is quantified by a method in which a high-purity thermoplastic resin in the form of particles or liquid is used as a sample instead of the form of a sheet. Therefore, the eluted ion concentration can be regarded as the absolute amount of each causative ion contained in the high-purity thermoplastic resin. The amount of eluted ions can be determined by analyzing the ion-exchanged water by ICP emission spectrometry or ion chromatography. The same applies to the sheet elution ion amount, which will be described later.

The high temperature and high humidity bias test is also called a high temperature and high humidity bias test (HHBT test). 3 to 100 V) is applied.

In this embodiment, migration and corrosion of the mounting structure 10 are suppressed even when the mounting structure 10 is exposed to conditions of a temperature of 85° C., a relative humidity of 85%, and a bias voltage of 6V. That is, the insulating properties of the sealing material 4 (that is, the sheet material after curing) are maintained. For example, the insulation resistance value of the sealing material 4 measured after exposing the mounting structure 10 to the above environment is 1×10 ⁸ Ω·cm or more. If the insulation resistance value is within this range, the short circuit of the second circuit member 2 is sufficiently suppressed. More preferably, the insulation resistance value of the sealing material 4 is 1×10 ¹⁰ Ω·cm or more. The insulation resistance value may be measured after the cured sheet material is exposed to the above environment.

A thermosetting resin composition contains an inorganic filler. Examples of inorganic fillers include silica such as fused silica, calcium carbonate, titanium white, silicon carbide, boron nitride, aluminum oxide, and aluminum nitride. Among them, fused silica is preferable because it contains few ionic impurities. The inorganic filler has an average particle size of, for example, 0.01 to 100 μm. The amount of the inorganic filler is preferably 1 to 5000 parts by mass, more preferably 10 to 3000 parts by mass, per 100 parts by mass of the thermosetting resin.

The thermosetting resin composition may contain a third component other than the above. Examples of the third component include curing accelerators, polymerization initiators, ion catchers, flame retardants, pigments, silane coupling agents, and thixotropic agents. The thermosetting resin composition may contain a thermoplastic resin other than the high-purity thermoplastic resin, but the amount thereof is preferably small. For example, the amount of the thermoplastic resin other than the high-purity thermoplastic resin is preferably less than 50 parts by mass, more preferably 20 parts by mass or less per 100 parts by mass of the thermosetting resin.

The curing accelerator is not particularly limited, but includes modified imidazole curing accelerators, modified aliphatic polyamine accelerators, modified polyamine accelerators, and the like. The curing accelerator is preferably used as a reaction product (adduct) with a resin such as an epoxy resin. These may be used alone or in combination of two or more. The activation temperature of the curing accelerator is preferably 60° C. or higher, more preferably 80° C. or higher, from the viewpoint of storage stability. Also, the activation temperature is preferably 250° C. or lower, more preferably 180° C. or lower. Here, the activation temperature is the temperature at which the curing of the thermosetting resin is rapidly accelerated by the action of the latent curing agent and/or curing accelerator.

The amount of curing accelerator varies depending on the type of curing accelerator. Generally, it is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the epoxy resin. When the curing accelerator is used as an adduct, the amount of the curing accelerator means the net amount of the curing accelerator excluding components other than the curing accelerator (such as epoxy resin).

A polymerization initiator develops curability by light irradiation and/or heating. A radical generator, an acid generator, a base generator and the like can be used as the polymerization initiator. Specifically, benzophenone-based compounds, hydroxyketone-based compounds, azo compounds, organic peroxides, sulfonium salts such as aromatic sulfonium salts and aliphatic sulfonium salts can be used. The amount of the polymerization initiator is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the epoxy resin.

Although the thickness of the sheet material is not particularly limited, it is, for example, 1 to 1500 μm. If the thickness of the sheet material is within this range, it becomes easy to suppress the short circuit of the second circuit member 2 . Furthermore, sufficient strength to seal the second circuit member 2 is easily ensured while maintaining the internal space. The thickness of the sheet material is more preferably 10-1000 μm, particularly preferably 20-500 μm. The sheet material may be a laminate in which a plurality of layers are laminated. In addition, in the sealing process, the second circuit member 2 of the sheet material (at least the layer facing the second circuit member 2 when the sheet material is a laminate) is sealed because the internal space S is easily maintained. The loss tangent tan δ at temperature t when stopped is preferably 1 or less.

The temperature t when the second circuit member 2 is sealed is the temperature of the laminated sheet 4P when the surface of the second circuit member 2 is covered with the laminated sheet 4P while the internal space S is maintained. be. The temperature of the lamination sheet 4P can be replaced with the set temperature of the heating means for the lamination sheet 4P in the sealing process. When the heating means for the laminated sheet 4P is a press, the temperature of the heating means is the set temperature of the press. When the heating means for the laminated sheet 4</b>P is a heater for heating the first circuit member 1 , the temperature of the heating means is the set temperature of the heater for the first circuit member 1 . The temperature t can be changed depending on the material of the laminated sheet 4P, etc., but is, for example, between room temperature +15°C (40°C) and 200°C. Specifically, the temperature t is, for example, 50 to 180.degree. When the second circuit member 2 is sealed, the laminated sheet 4P may be in an uncured state or in a semi-cured state.

The sheet material contains a high-purity thermoplastic resin as a sheeting agent. Therefore, the amount of causative ions (sheet absolute amount) contained in the entire sheet material that can be generated as ionic impurities is extremely small. For example, the total sheet absolute amount of Na ions, K ions and Cl ions (total sheet absolute amount) can be 25 ppm or less, and can be 15 ppm or less on a mass basis. At this time, the sheet absolute amount of Cl ions is preferably 10 ppm or less, more preferably 9 ppm or less, and particularly preferably 7 ppm or less on a mass basis. The sheet absolute amount of Na ions is preferably 10 ppm or less, more preferably 5 ppm or less on a mass basis. The sheet absolute amount of K ions is preferably 5 ppm or less, more preferably 2 ppm or less on a mass basis. The sheet absolute amount can be quantified by the same method as the absolute amount in the high-purity thermoplastic resin.

When the sheet absolute amount is extremely small, naturally the amount of ions that can be eluted from the sheet material into water (sheet eluted ion amount (concentration)) is also small. For example, when 100 g of 100 mesh pass (average particle size 150 μm or less) particles obtained by pulverizing a sheet material are immersed in 1000 g of ion-exchanged water at 121 ° C. at 2 atmospheres for 20 hours, the ion-exchanged water contains The total sheet elution ion concentration of Cl ions, Na ions and K ions (total sheet elution ion concentration) can be 15 ppm or less. The total sheet elution ion concentration is preferably 10 ppm or less, more preferably 8 ppm or less. The amount of ions eluted from the sheet is also quantified using, as a sample, particles obtained by pulverizing the sheet material instead of the sheet material itself. Therefore, the sheet elution ion concentration can be regarded as the absolute amount of each causative ion contained in the sheet (that is, the sheet absolute amount). That is, when the ion concentration eluted from the sheet is within this range, even in an environment such as a high-temperature, high-humidity bias test, migration, corrosion, etc. of the mounting structure are suppressed.

In particular, the sheet elution ion concentration of Na ions is preferably 8 ppm or less, more preferably 3 ppm or less. The sheet elution ion concentration of K ions is preferably 3 ppm or less, more preferably 1 ppm or less. The sheet elution ion concentration of Cl ions is preferably 7 ppm or less, more preferably 5 ppm or less.

[Manufacturing method of mounting structure]
A manufacturing method according to this embodiment will be described with reference to FIG. 2A and 2B are explanatory diagrams schematically showing the manufacturing method according to the present embodiment by cross-sections of the mounting member or the mounting structure 10. FIG.

The mounting structure 10 includes a first circuit member 1 and a plurality of second circuit members 2 mounted on the first circuit member 1 via bumps 3, for example. A first preparation step of preparing a mounting member having an internal space S formed between it and the circuit member 2; a second preparation step of preparing a sheet material 4P containing a high-purity thermoplastic resin; An arrangement step of arranging the sheet material 4P on the mounting member so as to face each other, pressing the sheet material 4P against the first circuit member 1, and heating the sheet material 4P to maintain the internal space S, and a sealing step of sealing the second circuit member 2 . Furthermore, a singulation step of dicing the obtained mounting structure 10 for each second circuit member 2 may be performed.

(First preparation step)
A mounting member including a first circuit member 1 and a plurality of second circuit members 2 to be mounted on the first circuit member 1 is prepared (FIG. 2(a)). The second circuit member 2 is mounted on the first circuit member 1 via bumps 3, for example. Therefore, an internal space S is formed between the first circuit member 1 and the second circuit member 2 .

The first circuit member 1 is, for example, at least one selected from the group consisting of semiconductor elements, semiconductor packages, glass substrates, resin substrates, ceramic substrates, and silicon substrates. These first circuit members may have a conductive material layer such as ACF (anisotropic conductive film) or ACP (anisotropic conductive paste) formed on the surface thereof. The resin substrate may be either a rigid resin substrate or a flexible resin substrate, and examples thereof include epoxy resin substrates (eg, glass epoxy substrates), bismaleimide triazine substrates, polyimide resin substrates, and fluororesin substrates. The first circuit member 1 may be a component-embedded substrate having a semiconductor chip or the like inside.

The second circuit member 2 is mounted on the first circuit member 1 via bumps 3 . Thereby, an internal space S is formed between the first circuit member 1 and the second circuit member 2 . The second circuit member 2 is an electronic component that needs to be sealed (hollow sealed) while maintaining the internal space S. As shown in FIG. Examples of the second circuit member 2 include RFIC, SAW, sensor chips (acceleration sensors, etc.), piezoelectric oscillator chips, crystal oscillator chips, and MEMS devices.

The bumps 3 are conductive, and the first circuit member 1 and the second circuit member 2 are electrically connected via the bumps 3 . Although the height of the bumps 3 is not particularly limited, it may be, for example, 40 to 70 μm. The material of the bumps 3 is also not particularly limited as long as it has conductivity, and examples thereof include solder balls.

That is, the mounting member has a chip-on-board (CoB) structure (chip-on-wafer (CoW), chip-on-film (CoF)) in which the second circuit member 2 is mounted on various first circuit members 1. , including chip-on-glass (CoG)), chip-on-chip (CoC) structures, chip-on-package (CoP) structures and package-on-package (PoP) structures. The mounting member may be a multi-layer mounting member in which the first circuit member 1 and/or the second circuit member 2 are laminated on the first circuit member 1 on which the second circuit member 2 is mounted.

(Second preparation step)
A sheet material 4P containing high-purity thermoplastic resin is prepared (FIG. 2(a)).
A manufacturing method of the sheet material 4P is not particularly limited. The sheet material 4P is prepared by, for example, a process of preparing a solvent paste or a solvent-free paste (hereinafter simply referred to as paste) containing the thermosetting resin composition, and a process of forming a thin film from the paste (thin film forming process ) and. After the thin film forming step, a step of gelling the obtained thin film (gelation step) is performed as necessary.

A thin film is formed by applying a paste to a peelable substrate using, for example, a die, a roll coater, a doctor blade, or the like. In this case, it is preferable to adjust the viscosity of the paste to be 10 to 10000 mPa·s during coating. When a solvent paste is used, the solvent may be removed by drying at 70 to 150° C. for 1 to 10 minutes. When the paste contains a pre-gelling agent, the gelation step is performed after the thin film formation step. The gelation step is performed by heating the thin film at a temperature lower than the curing temperature of the thermosetting resin (for example, 70-150° C.) for 1-10 minutes. The gelation step and solvent removal can be performed simultaneously.

(Placement process)
A sheet material 4P is placed on the mounting member so as to face the second circuit member 2 (FIG. 2(b)).
At this time, the plurality of second circuit members 2 may be covered with one sheet material 4P. Thereby, the sheet material 4P can be collectively arranged so as to face the surfaces of the plurality of second circuit members 2 and the surfaces of the first circuit members 1 between the second circuit members 2 . When the sheet material 4</b>P is a laminate, a layer having a loss tangent tan δ of 1 or less at the temperature t when the second circuit member 2 is sealed is opposed to the second circuit member 2 .

(sealing process)
While pressing the sheet material 4P against the first circuit member 1, the sheet material 4P is heated and cured. Thereby, the 2nd circuit member 2 is sealed, maintaining internal space S (FIG.2(c)).

The sheet material 4P is pressed against the first circuit member 1, for example, while the sheet material 4P is heated (heat press). As a result, the sheet material 4P adheres closely to the surface of the second circuit member 2, and can easily be extended to reach the surface of the first circuit member 1 between the second circuit members 2, and each second circuit. The reliability of sealing of the member 2 can be improved. Hot pressing may be performed under atmospheric pressure or under a reduced pressure atmosphere (for example, 0.001 to 0.05 MPa). The heating conditions during pressing are not particularly limited, and may be appropriately set according to the pressing method and the type of thermosetting resin. The heating is performed, for example, at 40 to 200° C. (preferably 50 to 180° C.) for 1 second to 300 minutes (preferably 3 seconds to 300 minutes).

Subsequently, the sheet material 4P is heated to cure the thermosetting resin in the sheet material 4P, thereby forming the encapsulant 4. As shown in FIG. Thereby, the second circuit member 2 is sealed. The conditions for heating the sheet material 4P (curing the thermosetting resin) may be appropriately set according to the type of the thermosetting resin. Curing of the thermosetting resin is performed, for example, at 50 to 200° C. (preferably 120 to 180° C.) for 1 second to 300 minutes (preferably 60 minutes to 300 minutes).

Heat pressing and curing of the thermosetting resin may be performed separately or simultaneously. For example, after hot pressing at a temperature lower than the curing temperature of the thermosetting resin contained in the sheet material 4P under a reduced pressure atmosphere, the reduced pressure is released and the thermosetting resin is cured by further heating at a high temperature under atmospheric pressure. may Alternatively, the sheet material 4P may be heat-pressed at a temperature lower than the curing temperature of the thermosetting resin contained in the sheet material 4P under atmospheric pressure, and then heated at a higher temperature to cure the thermosetting resin. Alternatively, the thermosetting resin may be cured during reduced pressure by hot pressing at a curing temperature in a reduced pressure atmosphere.

(Singulation process)
A singulation step of dicing the obtained mounting structure 10 for each second circuit member 2 may be performed (FIG. 2(d)). As a result, a chip-level mounted structure (mounted chip 20) is obtained.

[Example]
EXAMPLES Next, the present invention will be described more specifically based on examples. However, the following examples do not limit the present invention.

<Example 1>
(1) Fabrication of Sheet Material The following thermosetting resin composition was prepared to obtain a sheet material A (thickness: 200 μm, tan δ at temperature t (100° C.): 0.9).
Epoxy resin A (thermosetting resin: trade name LX01, manufactured by Osaka Soda Co., Ltd., bisphenol A type epoxy resin): 100 parts by mass Biphenylene type phenol novolak (phenolic curing agent): 110 parts by mass Acrylic resin A (high purity Thermoplastic resin: trade name SG-700AS, manufactured by Nagase ChemteX Co., Ltd.): 80 parts fused silica (inorganic filler: spherical, average particle size 25 μm): 1100 parts by mass 2-phenylimidazole (curing accelerator): 2 part by mass

Table 1 shows the absolute amounts of Na ions, K ions and Cl ions and the amount of eluted ions in acrylic resin A used. Table 1 also shows the sheet absolute amounts of Na ions, K ions, and Cl ions in the sheet material A and the sheet elution ion amounts.

The absolute amount of Cl ions contained in acrylic resin A was quantified by combustion chromatography.
Combustion conditions (manufactured by Mitsubishi Chemical Analytic Tech Co., Ltd., combustion decomposition device AQF-2100H)
Combustion temperature: 900-1000°C
Oxygen flow rate: 400 ml/min Argon flow rate: 200 ml/min Absorption liquid: ion-exchanged water (internal standard: Br)
Absorbing liquid volume: 10ml
Setting conditions for ion chromatography (Ion Chromatograph ICS-3000 manufactured by Thermo Fisher Scientific Co., Ltd.)
Detector: electrical conductivity Mobile phase: 2.7 mol/l potassium carbonate Flow rate: 1.5 ml/min Column temperature: 35°C
Measurement volume: 250 μl

The absolute amounts of Na ions and K ions contained in acrylic resin A were quantified by ICP emission spectrometry using an aqueous solution obtained by ashing 1 g of acrylic resin A and then dissolving it in hydrochloric acid aqueous solution as a sample. The ashing treatment was performed by heating the acrylic resin A at 550° C. for 120 minutes in an electric furnace.

Quantitation of each eluted ion in acrylic resin A was carried out by immersing 100 g of liquid acrylic resin A in 1000 g of ion-exchanged water at 121°C at 2 atm for 20 hours, and then analyzing the ion-exchanged water by ion chromatography. rice field.

The total absolute amount of Na ions, K ions and Cl ions contained in epoxy resin A was 116 ppm. The absolute amount of each causal ion contained in the epoxy resin A was quantified in the same manner as the absolute amount of each causal ion contained in the acrylic resin A.

The sheet absolute amount of Cl ions contained in sheet material A was the absolute amount of Cl ions contained in acrylic resin A, except that particles (100 mesh pass) obtained by pulverizing sheet material A were used as a sample. was quantified in the same manner as in the quantification of

Quantification of the sheet absolute amount of Na ions and K ions contained in sheet material A is included in acrylic resin A, except that particles (100 mesh pass) obtained by pulverizing sheet material A are used as samples. Quantitation was performed in the same manner as the absolute amount of Na ions and K ions.

Quantification of each eluted ion in sheet material A was performed in the same manner as quantification of eluted ions in acrylic resin A, except that particles (100 mesh pass) obtained by pulverizing sheet material A were used as a sample. .

(2) Fabrication of Mounting Structure A second circuit member having comb electrodes made of aluminum is mounted on a silicon substrate (first circuit member) via solder balls (bumps), and then heated and cooled to form a mounting member. got After covering the second circuit member side of the obtained mounting member with a sheet material, heat press (temperature 100° C., 1 minute) in a reduced pressure atmosphere (0.01 MPa), and then cure at 150° C. for 180 minutes. Then, the mounting structure A was obtained. The electrical resistance value (initial electrical resistance value) of the sealing material in the mounting structure A was 3×10 ¹⁶ Ω·cm.

(3) High Temperature and High Humidity Bias Test The mounting structure A was exposed to the conditions of 85° C., 85% relative humidity, and 6 V bias voltage for 500 hours. After that, the electrical resistance value of the sealing material of the mounting structure A was measured. Moreover, the mounting structure A was cut at a position where the cross section of the comb-shaped electrodes was visible, and observed with an electron microscope (500x magnification) to confirm the presence or absence of corrosion of the comb-shaped electrodes. The results are also shown in Table 1.

<Example 2>
A sheet was prepared in the same manner as in Example 1 except that epoxy resin B (trade name LX02F, manufactured by Osaka Soda Co., Ltd., bisphenol F type epoxy resin) was used instead of epoxy resin A, and the curing agent was 125 parts. A material B and a mounting structure B were produced and evaluated. The results are shown in Table 1. The total absolute amount of Na ions, K ions, and Cl ions contained in the epoxy resin B is 135 ppm, and the initial electrical resistance value of the sealing material in the mounting structure B is 3×10 ¹⁶ Ω·cm. Met.

<Example 3>
Example 1 was repeated except that 50 parts by weight of acrylic resin B (high-purity thermoplastic resin: SG-600TEA, manufactured by Nagase ChemteX Corporation) was used instead of acrylic resin A. A sheet material C and a mounting structure C were produced by the same method, and evaluated. The results are shown in Table 1. The initial electrical resistance value of the sealing material in the mounting structure C was 3×10 ¹⁶ Ω·cm.

<Comparative Example 1>
A sheet material a and a mounting structure a were produced and evaluated in the same manner as in Example 1, except that an acrylic resin a (trade name: F320, manufactured by Nippon Zeon Co., Ltd.) different from the acrylic resin A was used. rice field. The results are shown in Table 1. The initial electrical resistance value of the sealing material in the mounting structure a was 2×10 ¹⁶ Ω·cm.

In Examples 1 to 3, in which a high-purity thermoplastic resin with a small absolute amount of causative ions was used, even if the mounting structure was placed in an environment conforming to the high-temperature, high-humidity bias test, corrosion of the comb-shaped electrodes was not observed. Also, the electrical resistance values of the sealing materials were maintained at a high level.

In Example 2, an epoxy resin having a lower purity than that in Example 1 was used as the thermosetting resin. However, the amount of eluted ions eluted from the sheet material B is almost the same as that of the sheet material A of Example 1, and the occurrence of migration and corrosion is greatly affected by the absolute amount of causative ions contained in the thermoplastic resin. I understand.

INDUSTRIAL APPLICABILITY The mounting structure of the present invention is used in various applications because ionic impurities are less likely to occur even under high temperature and high humidity conditions.

10: Mounting structure 1: First circuit member 2: Second circuit member 3: Bump 4P: Sheet material 4: Sealing material (hardened sheet material)
20: mounted chip

Claims (11)

a mounting member including a first circuit member and a plurality of second circuit members mounted on the first circuit member, and a space formed between the first circuit member and the second circuit member; the process of preparing,
preparing a sheet material containing a thermosetting resin, a curing agent, a thermoplastic resin, and an inorganic filler;
disposing the sheet material on the mounting member so as to face the second circuit member;
a sealing step of pressing the sheet material against the first circuit member and heating the sheet material to seal the second circuit member while maintaining the space;
the thermosetting resin comprises an epoxy resin,
The total amount of chloride ions, sodium ions, and potassium ions contained in the thermoplastic resin is 30 ppm or less on a mass basis,
A method for manufacturing a mounting structure, wherein the total amount of chloride ions, sodium ions, and potassium ions contained in the sheet material is 25 ppm or less on a mass basis. The chloride ion contained in the thermoplastic resin is 15 ppm or less on a mass basis,
The sodium ion contained in the thermoplastic resin is 10 ppm or less on a mass basis,
2. The method of manufacturing a mounting structure according to claim 1, wherein said potassium ion contained in said thermoplastic resin is 5 ppm or less on a mass basis. 3. The method of manufacturing a mounting structure according to claim 1, wherein said thermoplastic resin is an acrylic resin. 4. The method for manufacturing a mounting structure according to claim 1, wherein the sheet material contains 5 to 200 parts by mass of the thermoplastic resin with respect to 100 parts by mass of the thermosetting resin. The cured sheet material has an insulation resistance value of 1×10 ⁸ Ω·cm or more after a high-temperature, high-humidity bias test is performed under conditions of a temperature of 85° C., a relative humidity of 85%, and a bias voltage of 6 V. 5. A method for manufacturing a mounting structure according to any one of 1 to 4. 2. A method for manufacturing a singulated mounting structure, comprising a singulation step of singulating the mounting structure obtained by the manufacturing method according to claim 1 by dicing for each of the second circuit members. A sheet material containing a thermosetting resin, a curing agent, a thermoplastic resin, and an inorganic filler,
the thermosetting resin comprises an epoxy resin,
The total amount of chloride ions, sodium ions, and potassium ions contained in the thermoplastic resin is 30 ppm or less on a mass basis,
The sheet material , wherein the total amount of chloride ions, sodium ions, and potassium ions contained in the sheet material is 25 ppm or less on a mass basis. The chloride ion contained in the thermoplastic resin is 15 ppm or less on a mass basis,
The sodium ion contained in the thermoplastic resin is 10 ppm or less on a mass basis,
8. The sheet material according to claim 7, wherein said potassium ions contained in said thermoplastic resin are 5 ppm or less on a mass basis. The sheet material according to claim 7 or 8, wherein said thermoplastic resin is an acrylic resin. Contains 5 to 200 parts by mass of the thermoplastic resin with respect to 100 parts by mass of the thermosetting resin
, The sheet material according to any one of claims 7 to 9. 11. The insulation resistance value after conducting a high-temperature, high-humidity bias test under conditions of a temperature of 85° C., a relative humidity of 85%, and a bias voltage of 6 V is 1×10 ⁸ Ω·cm or more. The sheet material described in the paragraph.

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