JP2000290627A - Thermosetting adhesive composition, adhesive, and production of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting adhesive composition containing a polyethylene-based polymer having a low dielectric constant and dielectric loss tangent (tan δ) and capable of post curing. SOLUTION: This composition is an adhesive composition containing (a) a first polyethylene-based polymer having an epoxy group in a molecule, (b) a second polyethylene-based polymer having no epoxy group in a molecule and (c) a rosin having a carboxyl group in a molecule, and in which the second polyethylene-based polymer contains an ethylene homopolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting adhesive composition, an adhesive and a method for producing the adhesive, and more particularly, it can be used as a reactive (thermosetting) heat-adhesive type adhesive. Adhesive composition, in particular, thermosetting adhesive composition for forming an adhesive that is low in dielectric constant and dielectric loss (dielectric loss tangent) and most suitable for manufacturing high-frequency IC packages, and obtained from the adhesive composition The present invention relates to an adhesive to be used and a method for producing the adhesive.

[0002]

2. Description of the Related Art As one of so-called hot-melt adhesives that can be thermally bonded, an adhesive containing a polyethylene-based polymer (including a copolymer) as a main component is known. It is used for Such a polyethylene-based adhesive is chemically stable, and its stability has been proven even in a test under severe conditions such as a pressure cooker test applied to semiconductor products and the like. For example, JP-A-9-25371 discloses a hot melt adhesive containing an ethylene-glycidyl methacrylate copolymer as a polyethylene polymer and rosin. The rosin is added as a tackifier (tackifier), and improves the adhesion to the metal surface in combination with the polar action of the glycidyl group of the ethylene-glycidyl methacrylate copolymer. Also,
Suitable rosins are rosin esters having an acid value of 100 or less, and therefore, this adhesive does not actively utilize the thermosetting reaction between rosin and an ethylene-glycidyl methacrylate copolymer. Further, this publication does not describe any intention of a cross-linking reaction between molecules of an ethylene-glycidyl methacrylate copolymer (polyethylene polymer).

When such an adhesive is used as a film adhesive for fixing lead pins of a lead frame of an IC, the film adhesive is immersed in a solder bath after thermocompression bonding, and further subjected to a thermal environment of 230 to 260 ° C. It is used under such conditions as to be left unattended. Therefore, it is required to have high heat resistance. However, the above publication does not include specific teachings on improvements for satisfying such required performance.

On the other hand, in order to have high heat resistance,
Since it is advantageous to increase the reactivity of the hot-melt adhesive, a so-called reactive (curable) hot-melt adhesive that enables a crosslinking reaction (post-cure) after bonding is also known. For example, a silanol-condensed hot melt adhesive using an olefin having a silyl group for post-crosslinking a polyolefin is known (Japanese Patent Application Laid-Open No. HEI 5 (1993) -205).
-295126). Further, a moisture-curable hot-melt adhesive in which a urethane prepolymer is blended with an ethylene copolymer (JP-A-4-8786) is also known. However, moisture is required to crosslink these materials, which is not suitable for applications such as IC package manufacturing.

Further, an adhesive polyolefin in which a polar component such as vinyl acetate, ethylene acrylate, maleic acid, styrene or the like is introduced into a polyolefin by copolymerization to increase the adhesive strength is known (JP-A-5-17735).
JP, JP-A-4-2277982, JP-A-2-2-2
61876, JP-A-2-255888, JP-A-2-180979, etc.). However, such a polyolefin has extremely low heat resistance as it is, and it is necessary to increase the amount of polar groups (reactive functional groups and the like) in the polyolefin molecule in order to obtain a sufficient adhesive strength. Further, as an adhesive containing polyethylene, which has heat resistance, an adhesive obtained by blending an epoxy resin and a latent curing agent with polyethylene is known (Japanese Patent Application Laid-Open No. Sho.
No. 3-301283).

Japanese Patent Application Laid-Open No. Hei 10-316955 discloses that
(a) an ethylene-glycidyl (meth) acrylate copolymer as a first polyethylene polymer, (b) an ethylene-alkyl (meth) acrylate copolymer as a second polyethylene polymer, and (c) a molecule. A hot-meltable adhesive composition comprising a rosin having a carboxyl group therein and having a crosslinked structure formed between ethylene units of the copolymer molecule is disclosed. This crosslinked structure can be formed by irradiating a mixture containing the components (a) to (c) with an electron beam. In this composition,
Conventional reactive (curable) hot melt adhesives have
It is advantageous in that it can solve problems such as slow cross-linking reaction, time-dependent deterioration of adhesive strength due to generation of reaction by-products, and gelation upon heating, and can be formed into a film adhesive without using a solvent.

[0007]

By the way, in recent years, as the clock frequency of a semiconductor chip has been increased and the degree of integration has been increased, an adhesive for an IC package having a low dielectric constant and a low dielectric loss (dielectric loss tangent) has been required. I have. Ethylene homopolymer has a characteristic of a low dielectric constant, but has poor adhesion and heat resistance. To improve adhesion and heat resistance,
As described above, it is necessary to use a polyethylene-based polymer (a copolymer having an ethylene unit and another polymerized unit) in which a polar group (including a reactive group) is introduced in the molecule. However, in order to obtain sufficient adhesive strength and heat resistance,
It is necessary to increase the amount of the polar group in the polyolefin molecule, and as a result, the dielectric constant and the dielectric loss tangent (tan δ) increase. In addition, when an epoxy resin is used in combination, the dielectric constant increases because the resin contains an aromatic component derived from the epoxy resin.

Accordingly, an object of the present invention is to provide a thermosetting adhesive composition containing a polyethylene polymer, which has a low dielectric constant and a low dielectric loss tangent (tan δ) and can be post-cured.

[0009]

In order to solve the above-mentioned problems, the present invention provides (a) a first resin having an epoxy group in a molecule;
An adhesive composition comprising: a polyethylene-based polymer; (b) a second polyethylene-based polymer having no epoxy group in the molecule; and (c) a rosin having a carboxyl group in the molecule. Provided is a thermosetting adhesive composition, wherein the polyethylene-based polymer comprises an ethylene homopolymer.

Here, how the thermosetting adhesive composition of the present invention solves the problems of the conventional adhesive will be described. In this specification, the term “polyethylene polymer” includes both ethylene homopolymers and copolymers containing ethylene units. The thermosetting adhesive composition of the present invention (hereinafter sometimes simply referred to as “adhesive composition”) is a first polyethylene-based polymer having an epoxy group in a molecule (hereinafter, referred to as “adhesive composition”) as an adhesive component. Polymer (a) ") and rosin having a carboxyl group in the molecule (hereinafter sometimes referred to as" rosin (c) "). Therefore, the adhesive formed from this thermosetting adhesive composition is (at the time of post-cure) an epoxy group of a polymer (a) such as an ethylene-glycidyl (meth) acrylate copolymer and a rosin (c). It can be thermally cured by reaction with a carboxyl group, and can effectively improve heat resistance and adhesiveness. In addition, this thermosetting reaction does not generate a reaction by-product such as water, and the crosslinking reaction is generally fast and does not require long post-curing. Further, no water is required for the crosslinking reaction. Therefore, it is also suitable for applications such as IC package manufacturing.

Further, the adhesive composition of the present invention may be referred to as a second polyethylene polymer having no epoxy group in the molecule, which is one of the adhesive components (hereinafter, referred to as “polymer (b)”). .) Contains an ethylene homopolymer. Therefore, the adhesive formed from the adhesive composition of the present invention can effectively reduce the dielectric constant and the dielectric loss. For example, the dielectric constant (ε) is 5,000 kHz
The measured value when an AC voltage of
Preferably it is 2.3 or less, particularly preferably in the range of 1.7 to 2.2. The dielectric loss (tan δ) is 5,000
The measured value when an AC voltage of kHz is applied.
25 or less, preferably 0.020 or less, particularly preferably 0.
001 to 0.018. The dielectric constant and the dielectric loss are measured values of the adhesive after the post cure.

Generally, in a composition containing an ethylene homopolymer and another copolymer, macroscopic phase separation proceeds during thermosetting. Such phase separation is very likely to impair the adhesive performance and the like. In the adhesive composition of the present invention, it is possible to introduce a crosslinked structure into the ethylene unit of the polyethylene polymer molecule, and in the adhesive of the present invention into which such a crosslinked structure has been introduced, such phase separation is prevented. Can be effectively prevented. Since the carboxyl group of the rosin (c) and the epoxy group of the polymer (a) do not substantially react with the adhesive before crosslinking (curing), post-curing can be effectively performed. it can.

The adhesive component (ie, (a) to (c) above)
The content of the ethylene homopolymer (hereinafter, also referred to as “PE polymer”) in the resin component containing the component (1) is not particularly limited as long as the effects of the present invention are not impaired.
However, usually 15 to 75% by weight, preferably 30 to 75% by weight.
It is 72% by weight, particularly preferably 40-70% by weight. P
If the amount of the E polymer is too small, the dielectric constant and the dielectric loss may not be effectively reduced, while if it is too large, the adhesiveness (peeling adhesive strength, etc.) and the heat resistance may be reduced.

In order to easily increase the adhesive force and effectively lower the dielectric constant, the PE polymer preferably comprises low density polyethylene (hereinafter sometimes referred to as “LDPE”). It is. The proportion of LDPE in the adhesive component is usually at least 15% by weight, preferably at least 18% by weight, particularly preferably in the range of 20 to 70% by weight. Also, PE
The proportion of LDPE in the polymer is usually at least 25% by weight,
It is preferably at least 30% by weight, particularly preferably at least 33% by weight. When the PE polymer is substantially composed of LDPE, it is preferable in that the adhesive force of the adhesive can be effectively increased and the dielectric constant can be effectively reduced.

When high-density polyethylene (hereinafter sometimes referred to as “HDPE”) is used in addition to LDPE,
The hardness of the adhesive can be effectively increased, and the dimensional stability of an IC package formed using the adhesive of the present invention can be improved. Further, the Young's modulus near 100 ° C. can be effectively increased, and high-frequency wire bonding can be easily performed using the adhesive of the present invention. For easy high-frequency wire bonding, the Young's modulus measured at 100 ° C. is usually 3 × 10
^The pressure is ⁶ Pa or more, preferably 7 × 10 ⁶ Pa or more, and particularly preferably 1 × 10 ⁷ to 10 ⁸ Pa.

When high-density polyethylene is used together, LD
Mixing weight ratio of PE (L) and HDPE (H) (L: H)
Is usually 25:75 to 80:20, preferably 30:70
-75: 25, particularly preferably 33: 67-70: 30. If the amount of LDPE is too small, the adhesive strength and the dielectric constant may not be effectively improved. In this specification, LDPE (low density polyethylene), HDPE
(High density polyethylene) is ASTM D 1248
The value of the density measured according to -84 is defined as follows. That is, the density of LDPE is 0.910 to 0.92.
5. The density of HDPE is 0.942 or more.

The adhesive of the present invention can be preferably produced by the following method. (I) An adhesive composition containing the adhesive component (a component containing the polymer (a), the polymer (b) and the rosin (c)) is prepared, and (ii) an electronic component is added to the adhesive composition. Irradiation is performed to introduce a crosslinked structure between the ethylene units of the polyethylene-based polymer molecules contained in the adhesive component to produce an adhesive. According to this method, it is possible to introduce a cross-linked structure between the polyethylene polymers while particularly effectively preventing gelation of the composition in the step of heat-forming a film or the like into a predetermined shape, which makes continuous production extremely easy. It is.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION (Thermosetting adhesive composition) The thermosetting adhesive composition of the present invention comprises a first polyethylene-based polymer (polymer having an epoxy group in a molecule essential for an adhesive component). In addition to (a)) and rosin (c), a second polyethylene-based polymer (polymer (b)) is included as a thermoplastic polymer having no epoxy group in the molecule. Thereby, the adhesiveness of the adhesive (thermal adhesive film adhesive etc.) formed from the adhesive composition can be easily increased. As described above, the second polyethylene-based polymer is P
Contains E polymer as an essential component.

The content of the polymer (a) is usually 20 to 70% by weight, preferably 23 to 60% by weight based on the total weight of the adhesive component.
% By weight, particularly preferably in the range from 25 to 55% by weight. If the content of the polymer (a) is too small, the reactivity (thermosetting) occurs.
May be reduced, while if too large, it may be difficult to lower the dielectric constant and the dielectric loss.

The fluidity during heating of the polymer (a) and the polymer (b) used in the present invention is measured by a melt flow rate (MFR: Melt Flow) measured at 190 ° C.
Rate), it is usually 1 [g / 10 min] or more. If it is at least 1, thermal bonding of the adhesive composition is possible. However, in order to facilitate the melt coating of the adhesive composition, it is preferably 30 or more.
On the other hand, if the MFR is too large, the cohesive strength of the cured composition may decrease. From these viewpoints, MFR
Is particularly preferably in the range of 35 to 1,000. Here, “MFR” is a value measured in accordance with JIS K 6760. Polymer (a) and polymer (b)
May be selected so that the MFR is in the above range.

The total proportion of the polymer (a) and the polymer (b) is usually from 60 to 99% by weight, preferably from 70 to 98% by weight, particularly preferably from 80 to 98% by weight, based on the whole adhesive composition. 9
A range of 7% by weight is preferred. If the content of these polymers is too small, the adhesiveness may be reduced. The adhesive composition of the present invention having the above composition is suitable as an adhesive precursor composition for forming a thermosetting adhesive such as the adhesive of the present invention.

(Thermosetting Adhesive) The adhesive formed from the adhesive composition of the present invention is solid at ordinary temperature (about 25 ° C., hereinafter, the term “normal temperature” means all about 25 ° C.). However, at a predetermined temperature, a relatively low pressure and a short time (for example, 0.1 to 10 kg / c at 100 to 200 ° C.)
(m ² , 0.1 to 30 seconds), and can be cured (crosslinked) by heating at the time of pressing or heating (post-curing) after the pressing. Therefore, it can be usefully used as a heat bonding-thermo-crosslinking type adhesive.

Such an adhesive can be formed, for example, by irradiating the adhesive composition with an electron beam and introducing a crosslinked structure between the ethylene units of the polyethylene polymer molecule. In this case, unlike the conventional radiation cross-linking type, the cross-linking can be completed by heating after arranging the adhesive on the portion of the adherend to which radiation cannot be applied or is difficult to be irradiated. The heating temperature at the time of performing thermosetting is usually 120 ° C. or more, and the heating time is usually 1 minute or more.

The adhesive composition of the present invention can be melted at a lower temperature (for example, 120 ° C. or lower) than a hot-melt composition such as a normal hot-melt adhesive, and can be easily subjected to hot-melt coating. Moreover, the fluidity at the time of hot melt is relatively high, and a solvent is not required for forming a coating or a film. That is, it is possible to form a thermosetting film adhesive in which the residual solvent after the completion of the bonding has no adverse effect.

In the adhesive composition of the present invention, the curing reaction between the polymer (a) and the rosin (c) at the heating temperature during melt coating or extrusion molding is extremely slow, and the adhesive composition is It does not gel or its viscosity (complex modulus) rises to levels that would make continuous production difficult. If the temperature is lower than 90 ° C., the curing reaction does not substantially proceed, so that the storage stability of the adhesive composition is extremely high. In addition, in the crosslinking (post-crosslinking, that is, post-curing) after the adhesive is applied to the adherend, the composition can be determined so that a thermal crosslinking reaction between the molecules of the polyethylene polymer is not essential. In the step of heat molding into a predetermined shape, gelation of the composition can be effectively prevented, and continuous production is easy. On the other hand, at least 130 ° C., preferably 1
At temperatures over 50 ° C, the curing reaction proceeds rapidly,
The time for heat curing treatment such as post cure can be easily reduced.

When the adhesive composition of the present invention further comprises an inorganic colloid dispersed in the adhesive component in addition to having the above-described thermosetting properties, the flow resistance during thermocompression bonding is reduced. growing. Therefore, the adhesive formed from the adhesive composition of the present invention can be used as a thermosetting-thermo-adhesive type adhesive having high flow resistance during thermocompression bonding and high heat resistance.

The adhesive according to the present invention is preferably formed by using the above adhesive composition and introducing a crosslinked structure between the ethylene units of the polyethylene polymer molecule contained in the adhesive component. Such a crosslinked structure acts to effectively prevent macroscopic phase separation during thermosetting. Further, such a crosslinked structure acts to improve the elastic modulus of the adhesive during thermocompression bonding. The improved elastic modulus prevents the adhesive layer sandwiched between the two adherends from flowing excessively during the thermocompression bonding operation, causing the adhesive to protrude from the adherends and adhere. It effectively prevents that the thickness of the agent layer becomes too small and the adhesive performance is reduced.

The elastic modulus of the adhesive for controlling the performance as described above is desirably defined by the storage elastic modulus (G ') at 250.degree. However, the adhesive of the present invention
Since the curing reaction proceeds by heating, it usually does not show a constant elastic modulus at the above-mentioned measurement temperature. Therefore, the storage elastic modulus of the adhesive is defined as follows. That is, the adhesive before use (before applying to the adherend, such as before thermocompression bonding) is used as a sample,
Using a dynamic viscoelasticity measuring device, raise the sample temperature from 90 ° C to 3
The temperature was raised to 00 ° C. at a rate of 5 ° C./min, and the storage elastic modulus was measured at a shear rate of 6.28 rad / sec.
Is defined as “storage modulus at 250 ° C. (G ′)”.

The storage modulus of the adhesive of the present invention as defined above is usually from 1 × 10 ³ to 1 × 10 ⁷ Pa, preferably 2 × 1 Pa.
0 ³ to 1 × 10 ⁶ Pa. If the storage elastic modulus is too small, the effect of preventing the flow in the thermocompression bonding operation is reduced, while if it is too large, the adhesion (temporary adhesion) in the instantaneous thermocompression bonding (for example, 30 seconds or less) becomes poor. Could be. If such temporary adhesion is poor, the component will be detached from the substrate when the bonded component is transported to a subsequent process (for example, a post cure process).

The intermolecular crosslinking is usually carried out between the molecules of the polymers (a), between the molecules of the polymers (b) and between the molecules of the polymers (a) and (b). Between molecules, it is formed between ethylene units. "Ethylene copolymers having no epoxy group in the molecule" such as ethylene-alkyl (meth) acrylate copolymers
Is contained in the composition as an additional component, it is also formed between the ethylene units in the molecules of the ethylene-based copolymer and the polymer (a) and / or the polymer (b). Such an intermolecular cross-link is formed, for example, by electron beam irradiation, whereby the ethylene unit of the polyethylene polymer molecule is radically activated, and a cross-linking reaction proceeds between the ethylene units.

The adhesive of the present invention is obtained by molding the adhesive composition into a film or other shape, and irradiating the molded product with an electron beam to form a cross-linked structure between polyethylene polymer molecules. Can be manufactured. The adhesive of the present invention,
For example, it can be manufactured by the following method. First, a master batch containing the polymer (a) and the polymer (b) is formed. The master batch is usually formed using a heatable kneading device such as an extruder. The master batch is usually formed in a pellet form to facilitate the subsequent kneading step. In addition, the polymer (a) and the polymer (b) may form a masterbatch by using the entire amount to be contained in the final adhesive composition, or a part of the polymer (a) is usually used. ) And (b) can also be used.
When a component other than the adhesive component such as an inorganic colloid is contained, it is preferable to knead the master batch in advance. Subsequently, the master batch pellets are put into a kneading device such as an extruder, and while being kneaded, rosin (c) that has been hot-melted is added to obtain an adhesive composition in which all components are uniformly mixed. . The adhesive composition thus obtained is formed into a film by a coating method such as T-die coating, and the formed film is irradiated with an electron beam to introduce a crosslinked structure between the molecules of the polymer. Thus, a film-like adhesive of the present invention can be obtained.

(First polyethylene polymer having an epoxy group in the molecule) A preferred example of the first polyethylene polymer having an epoxy group in the molecule (polymer (a)) is ethylene-glycidyl (meth) acrylate It is a copolymer. When the adhesive composition is heated at a predetermined temperature, the polymer (a) undergoes a curing reaction with the rosin (c) to increase the cohesive force of the cured product. Such a high cohesive force is advantageous for improving the adhesive performance such as the peel adhesive force of the adhesive composition. Further, by electron beam irradiation, a crosslinked structure is formed between the molecules of the polymer (a) or / and between the molecules of the polymer (b), thereby improving the elastic modulus of the adhesive composition during thermocompression bonding. Acts as if to let. On the other hand, the polymer (a) has an effect of melting the adhesive composition at a relatively low temperature and facilitating melt coating. In addition, good thermal adhesion (meaning adhesion to the adherend at the stage of being cooled and solidified after being melted and closely adhered to the adherend) is imparted to the adhesive composition.

The polymer (a) can be obtained, for example, by polymerizing a monomer mixture containing (i) a glycidyl (meth) acrylate monomer and (ii) an ethylene monomer as a starting monomer. Further, as long as the effects of the present invention are not impaired,
Propylene, alkyl (meth) acrylate, vinyl acetate and the like can be used. In this case, the alkyl group of the alkyl (meth) acrylate generally has a carbon number of 1 to 8. Specific examples of the polymer (a) include: 1) a binary copolymer of glycidyl (meth) acrylate and ethylene, 2) a tertiary copolymer of glycidyl (meth) acrylate, vinyl acetate and ethylene, 3) glycidyl ( Examples include terpolymers of (meth) acrylate, ethylene and alkyl (meth) acrylate.

Such a polymer (a) preferably contains a repeating unit obtained by polymerizing a monomer mixture of glycidyl (meth) acrylate and ethylene in an amount of usually 50% by weight or more based on the whole polymer. Contains 75% by weight or more. The weight ratio (G: E) of glycidyl (meth) acrylate (G) to ethylene (E) in the repeating unit is preferably from 50:50 to 1:99, particularly preferably from 20:80. The range is 5:95. If the content of ethylene is too small, the compatibility of the polymer (a) with the polymer (b) and the rosin (c) may be reduced, and a uniform composition may not be obtained, and electron beam crosslinking may be difficult. Could be. Conversely, if the content of ethylene is too large, the adhesive performance may be reduced. In addition, the polymer (a) can be used alone or as a mixture of two or more.

(Second polyethylene polymer having no epoxy group in the molecule) Second polyethylene polymer having no epoxy group in the molecule
The polyethylene-based polymer, i.e., polymer (b), acts to melt the adhesive composition of the adhesive composition at a relatively low temperature, facilitate melt coating, and enhance the thermal adhesion of the adhesive composition. . In addition, the electron beam irradiation forms a crosslinked structure between the molecules of the polymer (b) or / and between the molecules of the polymer (a), thereby improving the elastic modulus of the adhesive composition during thermocompression bonding. Acts as if to let. Further, since the second polyethylene-based polymer contains a PE polymer, the dielectric constant and the dielectric loss of the adhesive of the present invention can be effectively reduced. Further, the polymer (b) is compared with the polymer (a).
Has a low water absorption and thus acts to increase the water resistance of the adhesive composition or the adhesive.

The polymer (b) may contain, in addition to the PE polymer, an ethylene copolymer having no epoxy group in the molecule as long as the effects of the present invention are not impaired. As such an ethylene copolymer, for example, an ethylene-alkyl (meth) acrylate copolymer such as an ethylene-ethyl acrylate copolymer can be used. The ethylene-alkyl (meth) acrylate copolymer has high compatibility with the polymer (a), and can effectively enhance the thermocompression bonding property and the melt coating property of the adhesive composition without deteriorating the adhesiveness. Because you can.

The adhesive composition of the present invention can also contain a medium-density polyethylene (density of 0.926 to 0.940) as the polymer (b) as long as the effects of the present invention are not impaired. Furthermore, unless the effects of the present invention are impaired,
Thermoplastic polymers other than the polymers (a) and (b) can also be included.

(Rosin having a carboxyl group in the molecule) The rosin (c) used in the present invention has a carboxyl group in the molecule and reacts with the polymer (a) in a thermosetting operation to form an adhesive. The agent composition is cured by heat and acts to enhance the adhesive performance. As the rosin (c), gum rosin, wood rosin, tall oil rosin, or those obtained by chemically modifying them (for example, polymerized rosin) can be used. The acid value of rosin (c) is preferably from 100 to 30.
0, particularly preferably 150 to 250. If the acid value is too low, the reactivity with the polymer (a) decreases, and the curability of the composition may decrease. On the other hand, if the acid value is too high, the stability during heat molding (the effect of preventing an increase in viscosity). ) May decrease. Here, the “acid value” is a value expressed in mg of potassium hydroxide required to neutralize 1 g of the sample.

The softening point of the rosin (c) is preferably from 50 to
The temperature is 200C, particularly preferably 70-150C. If the softening point is too low, a reaction with the polymer (a) occurs during storage,
If the storage stability is lowered, on the contrary, if it is too high, the reactivity with the polymer (a) is lowered, and the curability of the composition may be lowered. Here, the “softening point” is a value measured according to JIS K 6730.

The proportion of rosin (c) contained in the adhesive component of the present invention is usually 1 to 40% by weight. 1% by weight
If the amount is less than the above, the curability and thermal adhesiveness of the composition may decrease. On the other hand, if it exceeds 40% by weight, the adhesive performance of the composition after curing may decrease. From such a viewpoint, it is preferably in the range of 2 to 30% by weight, particularly preferably 3 to 20% by weight. Rosin (c) is used alone or 2
It can be used as a mixture of more than one kind, and rosin having substantially no carboxyl group can be used in combination as long as the effect of the present invention is not impaired.

(Other Additives) The adhesive composition of the present invention has the above-mentioned (a) to (d) unless the effects of the present invention are impaired.
Various additives can be included in addition to the adhesive component (c). Such additives include antioxidants, UV absorbers, inorganic colloids and other fillers (polymer particles,
Conductive particles, pigments, etc.), lubricants such as wax, rubber components,
Tackifiers, crosslinking agents, curing accelerators and the like.

Since the inorganic colloid is usually contained in the dispersion in the form of colloid particles, the particles can be stably dispersed without sedimentation due to gravity. Therefore, in the adhesive composition of the present invention formed by drying such a dispersion, a state in which the components are uniformly mixed can be realized, the flow resistance at the time of thermocompression bonding can be increased, and the solder heat resistance can be improved. It is particularly easy to enhance. The content ratio of inorganic colloid is also
Although not particularly limited as long as the effects of the present invention are not impaired, it is usually 2 to 30% by weight based on the total amount of the adhesive composition. If the amount is less than 2% by weight, the dimensional stability may decrease. On the other hand, if it exceeds 30% by weight, the peel adhesion may decrease. Here, the “inorganic colloid” is usually fine particles having an average particle diameter in the range of 1 to 100 nm. For example, it is preferable that the inorganic particle sol and the adhesive component are mixed and dispersed and contained in the adhesive component. The inorganic particle sol is usually a mixture of (a) a dispersion medium and (b) the inorganic colloid dispersed in the dispersion medium.

As the inorganic colloid, silica colloid is preferable. This is because flow resistance during thermocompression bonding and solder heat resistance can be particularly effectively increased. On the other hand, as the inorganic colloid, one that has been suitably surface-treated with a surface treatment agent can also be used. With this, solder heat resistance and
It is possible to particularly effectively improve the flowability (increase in flow resistance) of the adhesive during thermocompression bonding. As the surface treating agent, for example, a surface modifying agent such as an organic silicon compound and an organic titanate can be used. As organic silicon compounds,
Alkylchlorosilane, alkylalkoxysilane, polydimethylsiloxane, alkyldisilazane, aminosilane, thiolsilane, epoxysilane, ureasilane and the like are preferred. These organic silicon compounds may be used alone or in any combination of two or more. A particularly preferred organosilicon compound is an alkyldisilazane. Especially excellent solder heat resistance, JEDEC (Join
t An adhesive capable of passing Level 1, which is the highest standard of soldering heat resistance of the Electron Device Engineering Council (Japan), can be formed.

The surface treatment of the inorganic colloid is usually performed by adding a surface treating agent to a dispersion liquid in which particles are dispersed, and further performing a dispersion operation. The dispersion after the surface treatment can be used as a sol containing the surface-treated colloid particles. After drying the dispersion, a pulverizing operation may be performed, if necessary, to obtain particles as surface-treated powder. The amount of the surface treatment agent is usually 0.001 to 30 parts by weight based on 100 parts by weight of the inorganic colloid.

(Film Adhesive) The film adhesive comprising the adhesive of the present invention has an advantageous use form as a heat-bonding type adhesive material, and at the same time can solve the above-mentioned problems of the conventional hot melt adhesive. For example, this film adhesive is easily thermally bonded only by sandwiching it between two adherends and performing thermocompression bonding at a predetermined temperature, and further performing a post-curing process at a predetermined temperature for a predetermined time. By
Demonstrates excellent adhesion performance. The curing reaction proceeds at a temperature in the range of 120 ° C. or more, and a sufficient adhesive force (for example, 4 to 15 kg / 25 mm or more) is obtained by heating (heating during pressure bonding or post-curing) for a time in the range of 1 minute to 24 hours. )
Can be expressed. The curing reaction rate at a temperature of 120 ° C. is slow, but sufficient (for example,
(10 hours or more), it is possible to exhibit the desired adhesive performance. To shorten the curing time,
What is necessary is just to heat in 30-300 degreeC.

The film adhesive is manufactured, for example, as follows. First, the adhesive composition of the present invention containing the above-mentioned components is prepared. Next, the adhesive composition is
The composition is melt-coated on a base material such as a release paper (liner) to form a film-like adhesive composition. Finally, the film-shaped adhesive composition is irradiated with an electron beam to form a crosslinked structure between molecules of a polymer containing an ethylene unit, thereby producing a film adhesive comprising the adhesive composition of the present invention. The preparation of the adhesive composition for producing the adhesive of the present invention is usually performed by using a kneading or mixing apparatus and mixing the components as raw materials until the components become substantially uniform. As such an apparatus, a kneader, a roll mill, an extruder, a planetary mixer, a homomixer or the like can be used. The temperature and time during mixing are selected so that the reaction between the polymer (a) and the rosin (c) does not substantially proceed, and is usually 20 to 120 ° C.
At a temperature in the range of 1 minute to 2 hours.

120 ° C., 6.28 rad of the adhesive composition
The complex viscosity η ^* measured under the condition of d / sec is preferably 500 to 1,000,000 poise, particularly preferably 1,2 poise.
The range is from 00 to 10,000 poise. Complex viscosity η ^*
If too low, mold to the specified thickness (including coating)
There is a possibility that it may be difficult to perform the molding, while if it is too high, it may be difficult to continuously mold.

The melt coating is usually 60 to 120
Perform at a temperature in the range of ° C. Conventional coating means such as a knife coater and a die coater are used for coating. Further, a film-like adhesive composition can be formed by an extrusion method without using a base material. The electron beam irradiation uses an electron beam accelerator, and usually has an acceleration voltage in the range of 150 to 500 kV,
Usually, the irradiation is performed with an irradiation amount in the range of 10 to 400 kGy.

The thickness of the film adhesive is preferably 0.0
The range is from 0.01 to 5 mm, particularly preferably from 0.005 to 0.5 mm. If the thickness is too thin, it tends to be difficult to handle as a film adhesive, and if it is too thick,
Crosslinking becomes uneven in the thickness direction, and the reliability as an adhesive may decrease.

Usually, one or both sides of the adhesive surface of the film adhesive are protected with a liner to produce a product. In addition, when the adhesiveness of the adhesive surface is relatively low, it is possible to produce a product without providing a liner. The liner-attached film adhesive is used, for example, as follows. First,
Remove the liner from the lined adhesive film,
An adhesive film is interposed between the adherend and the second adherend to form a laminate in which the first adherend, the film adhesive, and the second adherend are laminated in this order. I do. continue,
The laminate was heated to a temperature in the range of
Perform thermocompression bonding at a pressure in the range of 00 kg / cm ² ,
These three members form an adhesive structure in which they are in close contact with each other. According to this method, the two adherends can be adhered with a sufficient adhesive force in a time in the range of 0.1 to 30 seconds.

Needless to say, the film adhesive of the present invention exhibits a sufficient adhesive strength only by the thermocompression bonding as described above, but if it is desired to further increase the adhesive strength, post-curing is performed. That is, in the above-mentioned bonding method, the bonding structure is usually 120 ° C. or more, preferably 130 to 300 ° C.
Is post-cured at a temperature in the range of 1 minute to a time in the range of 1 minute to 24 hours. Particularly preferable conditions for shortening the time of the post-curing step are 140 to 200 ° C. and 30 minutes to 3 hours. This method is one of the best embodiments as a bonding method using the film adhesive of the present invention. Instead of the film adhesive, the surface of the first or second adherend is directly coated with the adhesive composition of the adhesive composition, and irradiated with an electron beam to form a layer of the adhesive composition. To form the above-mentioned adhesive structure.

(Applications) The adhesive composition or the adhesive of the present invention can be particularly suitably used in a process of manufacturing an IC package such as an electronic component such as bonding an IC component to a printed circuit board. In addition, fluorine-based polymers, polyamide, polyimide, polyetherimide, polycarbonate, polyethylene, polypropylene, polyester, between the polymer adherends such as epoxy resin, or
It can also be suitably used for bonding a polymer adherend to an article made of another material (semiconductor such as fiber, metal, silicon, ceramic, glass, etc.). For example, specific examples of the metal include copper, iron, nickel, gold, silver, aluminum, tungsten, molybdenum, and platinum. The adhesive composition or the adhesive of the present invention can be thermocompression-bonded at a relatively low temperature, and exhibits sufficient adhesive strength only by performing post-curing at a relatively low temperature for a short time. Therefore, it is suitable for bonding an adherend having relatively low heat resistance.

In the production of the adhesive composition of the present invention,
Does not include a polymerization step using a monomer as a starting material. Therefore, unreacted monomer and volatile organic matter derived from the monomer remaining in the composition can be reduced as much as possible. That is, it is possible to effectively prevent foaming due to volatile components generated at the time of solder reflow and generation of a monomer odor that is relatively unpleasant for a user. On the other hand, when the adhesive composition of the present invention is used as an adhesive layer fixed to a base material such as a polymer film, a fiber cloth, or a metal foil, it can be used as a thermocompression bonding tape. Further, the adhesive composition according to the present invention can be used as a sealing material in addition to an adhesive application.

[0054]

Examples 1 to 9 and Comparative Examples 1 and 2 The adhesive compositions of the respective examples were prepared by mixing the following components in the same weight ratio, and using a twin-screw extruder to obtain about 110 parts. ° C
At each temperature until each component became uniform.

Example 1: CG5001 / FL60 / KE604 = 50
/ 50/5 Example 2: CG5001 / FL60 / KE604 = 40
/ 60/5 Example 3: CG5001 / FL60 / KE604 = 30
/ 70/5 Example 4: CG5001 / FL60 / J300 / KE6
04 = 50/35/15/5 Example 5: CG5001 / FL60 / J300 / KR8
5 = 40/20/40/10 Example 6: CG5001 / FL60 / J300 / KR8
5 = 40/30/30/10 Example 7: CG5001 / FL60 / J300 / KR8
5 = 40/30/30/20 Example 8: CG5001 / FL60 / J300 / KR8
5 = 50/25/25/10 Example 9: CG5001 / FL60 / J300 / KR8
5 = 50/25/25/20 Comparative Example 1: NUC6070 Comparative Example 2: CG5001 / NUC6070 / NUC6
570 / KE604 = 80/6/14/5 CG5001: an ethylene-glycidyl methacrylate copolymer manufactured by Sumitomo Chemical Co., Ltd. (Bondfast;
(MFR = 350 g / 10 min.) NUC6070: Nippon Unicar Co., Ltd. ethylene-
Ethyl acrylate copolymer (EEA; MFR = 250 g)
NUC6570: Ethylene- manufactured by Nippon Unicar Co., Ltd.
Ethyl acrylate copolymer (EEA; MFR = 20 g)
/ 10 min.) KR-85: Rosin manufactured by Arakawa Chemical (acid value 170 mg KOH)
/ G) KE604: Arokawa Chemical rosin (acid value 240mgKOH
/ G) FL60: low density polyethylene manufactured by Mitsui Petrochemical Industries; M
IRASON; MFR = 70 g / 10 min. J300: High-density polyethylene manufactured by Asahi Kasei Corporation Suntech HD J300 (MFR = 42 g / 10 m)
in.)

The adhesive composition of each example was formed into a film having a thickness of 100 μm by die coating, and irradiated with an electron beam under the conditions of an acceleration voltage of 200 kV and an irradiation amount of 150 kGy. Formed.

The evaluation of the adhesive in each example was performed as follows. Peel adhesion: 10 mm x 30 mm film adhesive
Copper plate (length 30mm x width 25mm x thickness 0.3mm)
And a polyimide film having a thickness of 50 μm,
At 5 N (Newton) / cm ^{2 for} 10 seconds.
A laminate composed of three layers of copper plate / film adhesive / polyimide film was formed, and the laminate was post-cured at 150 ° C. for 2 hours. After the post cure, the 90 ° peel force (interfacial peel force between the polyimide film and the film adhesive) when the polyimide film of the laminate was pulled at a speed of 50 mm / min was measured, and the maximum value of the measured values was used as the peel adhesive force. did.

Heat resistance (solder heat resistance): First, 15 mm ×
A 15 mm film adhesive is sandwiched between a 0.6 mm thick stainless steel plate and a 125 μm thick polyimide,
At 5 N (Newton) / cm ^{2 for} 10 seconds.
Stainless steel plate / film adhesive / polyimide film 3
A laminate composed of the layers was formed. This laminate is heated at 150 ° C.
For 2 hours to prepare a test sample. The sample was heated on a hot plate at 205 ° C. after wet heat aging, and the case where no foaming or peeling occurred was evaluated as “OK”, and the case where at least one of foaming or peeling occurred was evaluated as “not good”. Passed (NG) ". The wet heat aging conditions were a temperature of 30 ° C., a relative humidity of 70% RH, and an aging time of one week.

Storage elastic modulus: Using the film adhesive of each example as a sample, a dynamic viscoelasticity device (model number:
RDAII), the storage shear modulus G ′ was measured.
Each elastic modulus is a measured value at each of 150 ° C., 200 ° C., and 250 ° C. when the temperature was raised from 90 ° C. to 300 ° C. at 5 ° C./min. The shear rate is 6.28ra
d / sec.

Dielectric constant ε and dielectric loss tangent tan δ: The adhesive film of each example was post-cured at 150 ° C. for 2 hours and used as a sample. The measurement was performed using an "impedance analyzer (product number) 4192A".

Storage Young's Modulus E ': A dynamic viscoelastic device (model number: RS) manufactured by Rheometrics Co., Ltd.
Using A), the storage Young's modulus E ′ was measured at 100 ° C. and a shear rate of 6.28 rad / sec.

SD Hardness (Shore D Hardness) The film adhesive of each example was post-cured at 150 ° C. for 2 hours, and was measured according to JIS K7215.

Tables 1 and 2 show the evaluation results.

[Table 1]

[0064]

[Table 2]

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomihiro Hara 3-8-8 Minamihashimoto, Sagamihara City, Kanagawa Prefecture Within Sumitomo 3M Limited (72) Inventor Naoyuki Toriumi 3-8-8 Minamihashimoto, Sagamihara City, Kanagawa Prefecture Sumitomo 3M Limited F term (reference) 4J040 BA202 DA032 DA061 DA062 DF061 EC231 JB02 JB07 LA09 NA19 NA20

Claims (3)

[Claims] (A) a first resin having an epoxy group in the molecule;
An adhesive composition comprising: a polyethylene-based polymer; (b) a second polyethylene-based polymer having no epoxy group in the molecule; and (c) a rosin having a carboxyl group in the molecule. A thermosetting adhesive composition, wherein the polyethylene-based polymer comprises an ethylene homopolymer. 2. An adhesive comprising the thermosetting adhesive composition according to claim 1, wherein a crosslinked structure is introduced between ethylene units of the polyethylene polymer molecule. 3. A method for producing an adhesive, comprising a step of irradiating the adhesive composition of claim 1 with an electron beam to introduce a crosslinked structure between molecules of the polyethylene-based polymer.