JP2002129125A - Bonding material, and electronic component module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding material having a small rate of change in a breakdown elongation and an excellent heat fatigue resistance after a high temperature shelf test, considering that a bonding material layer in a wiring board composing electronic component modules is apt to crack owing to enlarging in a rate of change in a breakdown elongation by the curing and degrading of the resin caused by a long term heat hysteresis. SOLUTION: The bonding material comprises an epoxy resin mixture, a hardener initiating reaction at a temperature in the range of 100-200 deg.C, a thermoplastic resin having a weight-average molecular weight of 10,000-500,000, a polyether-based elastomer to crosslink with the epoxy resins and an inorganic insulating filler, with a breakdown elongation change ratio after the high temperature shelf test being -50 to 50%, when measured by the method prescribed in JIS-C-5012.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive for forming an adhesive layer on a surface of which a wiring conductor layer is adhered, and to an electronic component module using the same. The present invention relates to an adhesive material having a small rate of change in elongation at break, and an electronic component module having excellent thermal fatigue resistance such as a temperature cycle test using the same and excellent connection reliability when mounting electronic components.

[0002]

2. Description of the Related Art In recent years, there has been a growing demand for smaller, thinner, lighter, and higher quality electronic devices as represented by various types of communication devices in the mobile and portable fields.
The electronic component modules mounted on such electronic devices are also required to be small, highly functional, and highly reliable. For this reason, the demand for higher density and higher reliability is increasing for the wiring boards constituting such electronic component modules.

In response to such demands, in recent years, ceramic wiring boards using ceramics such as aluminum oxide sintered bodies as insulating substrates have been replaced with lightweight and miniaturized insulating substrates made of glass fibers and organic resins. A so-called printed wiring board, in which a wiring conductor layer is formed by a thin film forming method using a low-resistance metal such as copper or nickel, has been used for an electronic component module. further,
This printed wiring board is also changing to a build-up wiring board capable of higher-density wiring.

In such a build-up wiring board, for example, a photosensitive resin is applied and dried on an insulating substrate made of glass fiber and epoxy resin to form an insulating layer.
An opening is formed by exposure and development, and further, the insulating layer is cured by irradiating ultraviolet rays, or a film made of a thermosetting resin is laminated on an insulating substrate, and then thermally cured to form an insulating layer, Furthermore, by drilling an opening with a laser, and then, after these surfaces are chemically roughened, a copper thin film is deposited and formed by using an electroless copper plating method and an electrolytic copper plating method. It is manufactured by forming a conductor layer in the opening, forming a wiring conductor layer on the surface of the insulating layer, and further sequentially forming such an insulating layer and the wiring conductor layer.

Generally, the insulating layer of such a build-up wiring board is formed by using an adhesive containing an inorganic insulating filler in a thermosetting resin such as an epoxy resin having excellent heat resistance. However, this adhesive contains a resin such as acrylonitrile butadiene rubber (NBR) having a low elastic modulus in order to relieve thermal stress in a reflow furnace when electronic components such as semiconductor elements are mounted on a wiring board. This has the problem that the insulating property of the insulating layer is reduced in a moisture resistance test such as a standing test in a wet state due to the hygroscopicity.

Therefore, in order to solve such a problem, as an adhesive for a build-up wiring board, a heat-resistant adhesive is used.
Polyfunctional cyanate ester containing butadiene / alkyl methacrylate / styrene copolymer with excellent moisture resistance
A thermosetting resin composition comprising an epoxy resin composition has been proposed (see Japanese Patent Application Laid-Open No. H11-12491).

[0007]

However, since this thermosetting resin composition is composed of a polyfunctional cyanate ester and an epoxy resin, crosslinking of these resins when left for a long time under a high temperature condition. The adhesive layer is hardened and brittle, and shows a hardening deterioration property, for example, its elongation at break rapidly decreases from about 10% to about 2%,
As a result, in a thermal fatigue resistance test such as a long-term high-temperature storage test, a crack is generated in the adhesive layer, and the wiring conductor layer formed on the surface is cut, thereby causing poor conduction. Had.

Further, this thermosetting resin composition comprises a rubber component, butadiene / alkyl methacrylate / styrene copolymer, which is a polyfunctional cyanate / epoxy resin, for relaxing thermal stress during mounting of electronic parts. Although it is dispersed in the resin, since the butadiene / alkyl methacrylate / styrene copolymer has no functional group that crosslinks with the polyfunctional cyanate / epoxy resin, the bond between the two is strong. In a thermal fatigue test such as a temperature cycle test, stress is concentrated at the joint between the two, cracks are generated, and the wiring conductor layer formed on the surface of the adhesive layer is cut off. There is also a problem that a defect is generated.

Furthermore, in an electronic component module in which an electronic component is mounted on a wiring board on which an insulating layer is formed using such a thermosetting resin composition, the elongation at break of the insulating layer is also caused by heat during mounting of the electronic component. And the connection part between the electronic component and the wiring board is disconnected.

The present invention has been made in view of the problems of the prior art, and has as its object to provide an adhesive having a small rate of change in elongation at break after a high-temperature storage test, and a heat-resistant adhesive such as a temperature cycle test using the same. An object of the present invention is to provide an electronic component module having excellent fatigue properties and excellent connection reliability when mounting electronic components.

[0011]

The adhesive of the present invention comprises an epoxy resin mixture, and the epoxy resin mixture and 100 to 200
It consists of a curing agent that initiates a curing reaction at a temperature of ° C, a thermoplastic resin having a weight average molecular weight of 10,000 to 500,000, a polyether-based elastomer that crosslinks with an epoxy resin, and an inorganic insulating filler. Breaking elongation change rate
-50 to 50 measured by the method specified in JIS-C-5012
%.

[0012] In the adhesive of the present invention, the epoxy resin mixture may comprise 20 to 80% by weight of a polyfunctional epoxy resin and 20 to 80% by weight of a bifunctional epoxy resin. By external addition, 2 to 10% by weight of a curing agent, 5 to 30% by weight of a thermoplastic resin, 10 to 40% by weight of a polyether elastomer, and 3 to 10% by weight of an inorganic insulating filler are added. It is a feature.

Further, the adhesive of the present invention is characterized in that it is in the form of a film in the above constitution.

Further, the electronic component module of the present invention is formed on an insulating substrate, an adhesive layer formed on the insulating substrate by using the above-mentioned adhesive, and on each surface of the insulating substrate and the adhesive layer. An electronic device comprising an electronic component mounted on a wiring board including a plurality of wiring conductor layers and a through conductor formed in a through hole formed in the adhesive layer and electrically connecting the plurality of wiring conductor layers. A component module, wherein a wiring conductor layer formed on a surface of a wiring board and each electrode of an electronic component are electrically connected via a conductor bump.

According to the adhesive of the present invention, the crosslink density can be increased due to the inclusion of the epoxy resin mixture. As a result, molecular breakage of the resin due to heat and intrusion of moisture into the resin are suppressed. Thus, an adhesive having good heat resistance and moisture resistance can be obtained. In addition, the weight average molecular weight is 1000
Since the thermoplastic resin of 0 to 500,000 is contained, an adhesive having good stretchability and good film moldability can be obtained. Furthermore, it contains a polyether-based elastomer that crosslinks with the epoxy resin, and the polyether bond of the polyether-based elastomer shows a softening deterioration property in which the bond is broken by continuing heating. Deterioration and curing deterioration caused by the progress of crosslinking by continuing to heat the epoxy resin cancel each other out.
It can be a small value of -50 to 50% as measured by the method specified in -5012. In addition, since the polyether-based elastomer has a functional group that crosslinks with the epoxy resin, the epoxy resin and the polyether-based elastomer are covalently bonded, and the bond between the two can be strengthened. Even if stress is concentrated at the joint, no crack is generated, and an adhesive having good thermal fatigue resistance can be obtained.

According to the electronic component module of the present invention, each electrode of the electronic component is electrically connected to the wiring conductor layer formed on the surface of the wiring board using the above-mentioned adhesive layer, via the conductor bump. In addition, an electronic component module having good connection reliability in a thermal fatigue test such as a temperature cycle test and having no disconnection when mounting the electronic component can be provided.

[0017]

Next, the adhesive of the present invention and an electronic component module using the same will be described in detail.

The adhesive of the present invention comprises an epoxy resin mixture, a curing agent which initiates a curing reaction with the epoxy resin mixture at a temperature of 100 to 200 ° C., and a weight average molecular weight of 10,000 to 500.
000 thermoplastic resin, a polyether-based elastomer crosslinked with an epoxy resin, and an inorganic insulating filler, and the breaking elongation change rate after a high-temperature storage test is JIS-C-50.
It is -50 to 50% as measured by the method specified in 12.

The adhesive of the present invention may be used in the form of a varnish or a solid film. However, the adhesive is preferably in the form of a film from the viewpoints of surface flatness and easy control of thickness. The thickness of the sheet is preferably as thin as several μm to several hundred μm.

Since the adhesive of the present invention contains the epoxy resin mixture, the crosslink density can be increased, so that the molecular breakage of the resin due to heat and the penetration of moisture into the resin can be suppressed. And an adhesive excellent in heat resistance and moisture resistance.

As such an epoxy resin mixture,
From the viewpoints of heat resistance, chemical resistance, electrical properties, and workability, a mixture of a polyfunctional epoxy resin and a bifunctional epoxy resin is preferable. In particular, the ratio of the polyfunctional epoxy resin to the bifunctional epoxy resin is preferably a polyfunctional epoxy resin. 20-80% by weight of resin,
The content is preferably 20 to 80% by weight of the bifunctional epoxy resin. If the amount of the polyfunctional epoxy resin is less than 20% by weight, the crosslink density of the adhesive tends to decrease and the chemical resistance tends to decrease. If the amount exceeds 80% by weight, the crosslink density increases and the adhesive becomes flexible. There is a tendency that the elongation at break after storage at high temperature tends to be reduced due to the reduced properties. Therefore, the ratio of the polyfunctional epoxy resin to the bifunctional epoxy resin is set to 20 to
It is preferred that the content be in the range of 80% by weight and 20 to 80% by weight of the bifunctional epoxy resin.

Such polyfunctional epoxy resins include:
Phenol novolak type epoxy resin, orthocresol novolak type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, triglycidyl isocyanurate, alicyclic epoxy resin, etc. are used. A-type epoxy resin, bisphenol F-type epoxy resin, bisphenol S-type epoxy resin, biphenol-type epoxy resin and the like are used. Furthermore, it is also possible to use a brominated epoxy resin in combination to impart flame retardancy to these epoxy resins.

The adhesive of the present invention contains a curing agent which initiates a curing reaction at a temperature of 100 to 200 ° C. with the epoxy resin mixture in an amount of 2 to 10% by weight based on the epoxy resin mixture. When the reaction start temperature of the curing agent is lower than 100 ° C., the curing of the film proceeds excessively in the drying step at the time of film formation, the flexibility tends to be lost, and a problem occurs in handling the film. If the temperature exceeds 200 ° C., the oxidative deterioration of the epoxy resin starts, the film becomes brittle, and the handling tends to be difficult. Therefore, the reaction initiation temperature of the curing agent is preferably in the range of 100 to 200 ° C.

When the amount of the curing agent added is less than 2% by weight of the external addition to the epoxy resin mixture, the crosslinking density tends to be low and the moisture resistance and chemical resistance tend to be inferior.
If it exceeds, the crosslink density becomes too high, the flexibility of the cured film is reduced, and the thermal fatigue reliability in a temperature cycle test or the like tends to be reduced. Therefore, the amount of the curing agent added is preferably in the range of 2 to 10% by weight, based on the external addition to the epoxy resin mixture.

Examples of such a curing agent include metaphenylenediamine having a reaction initiation temperature of 130 to 150 ° C., diaminodiphenylmethane having a reaction initiation temperature of 120 to 180 ° C., and a reaction initiation temperature of 110 to 200 ° C. with an epoxy resin mixture. Aromatic amines such as diaminodiphenylsulfone
Dicyandiamide at 160-180 ° C, reaction start temperature 160-1
2,4-diamino-6- (2-methyl-1-imidazolylethyl) -1,3,5-triazine at 80 ° C .;
2,2,4-diamino-6- (2-undecyl-
A structure having a rigid aromatic amine or triazine represented by a triazine such as (1-imidazolylethyl) -1,3,5-triazine is used.

If the reaction initiation temperature is suitable, a phenolic curing agent and a curing accelerator may be used in combination. For example, a phenolic curing agent such as a phenol novolak resin or an ortho novolak resin, and a curing accelerator such as A curing agent and a curing accelerator having a reaction initiation temperature of 100 to 200 ° C., such as an imidazole compound or an organic sulfone compound, may be used.

Further, since the adhesive of the present invention contains 5 to 30% by weight of a thermoplastic resin having a weight-average molecular weight of 10,000 to 500,000 based on the epoxy resin mixture, it has good stretchability and film properties. Can be used as an adhesive excellent in moldability. If the weight average molecular weight of the thermoplastic resin is less than 10,000, the film tends to be brittle and the moldability tends to deteriorate, and if it exceeds 500,000, the viscosity of the adhesive increases and a film having a uniform thickness can be obtained. Tends to disappear. Therefore, the weight average molecular weight of the thermoplastic resin is preferably in the range of 10,000 to 500,000.

If the amount of the thermoplastic resin is less than 5% by weight of the external addition to the epoxy resin mixture, the film tends to be brittle and good stretchability cannot be obtained. It tends to be poor. Therefore, it is preferable that the amount of the thermoplastic resin added is in the range of 5 to 30% by weight based on the external addition to the epoxy resin mixture.

Examples of such a thermoplastic resin include polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) and alkyl adipates, and acrylates such as polymethyl methacrylate and polybutyl methacrylate. Those that dissolve in a liquid are preferred.

The adhesive of the present invention contains a polyether-based elastomer which crosslinks with an epoxy resin in an amount of 10 to 40% by weight based on the epoxy resin mixture. Generally, an epoxy resin, which is a thermosetting resin, has such a property that, when heating is continued, crosslinking progresses, curing deterioration occurs, and elongation at break gradually decreases. However, the adhesive of the present invention contains a polyether-based elastomer that crosslinks with the epoxy resin, and has a property of softening deterioration in which the bond is broken by continuing to heat the polyether bond of the polyether-based elastomer. The elongation at break of the film is improved, and the rate of change of the elongation at break of the film can be reduced by counteracting the reduction of the elongation at break due to the curing deterioration of the epoxy resin. Is measured by a method specified in JIS-C-5012 to be -50 to 50%.

Further, the polyether-based elastomer is
Since it has a functional group that crosslinks with the epoxy resin, the epoxy resin and the polyether-based elastomer can be covalently bonded and the bond between the two can be strengthened.
Even if stress is concentrated on the joint between the two in a heat cycle fatigue test such as a temperature cycle test, no crack is generated, and an adhesive having good heat fatigue resistance can be obtained.

Examples of such polyether elastomers include epoxy-modified polytetramethylene glycol and carboxyl-modified polypropylene having two or more functional groups such as a hydroxyl group, a carboxyl group, and an epoxy group covalently bonded to an epoxy group in one molecular chain. Glycol / epoxy-modified polyethylene glycol / epoxy-modified polybutylene glycol and the like are used. It should be noted that these polyether-based elastomers can be favorably crosslinked with an epoxy resin if they have two or more functional groups in one molecular chain, but in order to more strongly crosslink with an epoxy resin, It is preferable to have a functional group at both ends of the molecular chain.

The amount of the polyether-based elastomer to be added is preferably in the range of 10 to 40% by weight based on the epoxy resin mixture, and if the amount is less than 10% by weight, the flexibility tends to decrease. When the content exceeds 40% by weight, the crosslinking density of the adhesive decreases, and the moisture resistance and chemical resistance tend to decrease. Therefore, the amount of the polyether-based elastomer is preferably in the range of 10 to 40% by weight.

Further, the weight average molecular weight of the polyether-based elastomer is preferably in the range of 1,000 to 10,000, and if the weight average molecular weight is less than 1,000, it tends to be inferior in flexibility and insufficient in rubber elasticity. If it is larger, the dispersibility tends to be poor and phase separation tends to occur. Therefore, the weight average molecular weight of the polyether elastomer is
A range from 1000 to 10,000 is preferred.

Furthermore, the adhesive of the present invention contains 3 to 10% by weight of an inorganic insulating filler in addition to the epoxy resin mixture. This inorganic insulating filler has the function of increasing the strength of the film. If the amount of the inorganic insulating filler is less than 3% by weight, the flatness of the film tends to deteriorate. There is a tendency that the workability of the film such as the formation of holes is deteriorated. Therefore, the amount of the inorganic insulating filler is preferably in the range of 3 to 10% by weight.

As such an inorganic insulating filler,
Insulating inorganic fine powders such as silica, aluminum oxide, aluminum nitride, silicon carbide, calcium titanate, titanium oxide, and zeolite are used. The shape may be any of spherical, crushed, plate-like, etc. From the viewpoint of the spherical shape, also from the viewpoint of the coefficient of thermal expansion silica and aluminum oxide, further from the viewpoint of the formability of the film the average particle size is 20μm or less, from the viewpoint of the perforation of the through-hole average It is preferable that the powder is a spherical fine powder having a particle diameter of 10 μm or less and an average particle diameter of 7 μm or less from the viewpoint of filling properties of the inorganic insulating filler.

In the adhesive of the present invention, the rate of change in elongation at break after the high-temperature storage test was -50 to 50% as measured by the method specified in JIS-C-5012. An adhesive excellent in thermal fatigue resistance for a reliability test such as a cycle test can be obtained.

The rate of change in elongation at break after the high temperature storage test is -50.
%, There is a tendency that the crosslink density becomes too large and cracks occur in the film, resulting in poor heat fatigue resistance.
%, The crosslink density of the resin tends to decrease, resulting in poor moisture resistance and chemical resistance. Therefore, the rate of change in elongation at break after the high-temperature storage test is preferably in the range of -50 to 50%.

Here, the elongation at break refers to the elongation of the film when a film having a thickness of several tens of μm is molded with an adhesive and completely cured, and then pulled at a constant speed until the film is broken. The rate of change in elongation at break is 500 ° C under the temperature conditions of 150 ° C specified in JIS-C-5012.
It is calculated by measuring the elongation at break before and after the high-temperature storage test where the time is kept.

Further, in the adhesive of the present invention, in order to obtain good moldability when forming a film, a material such as methyl ethyl ketone (MEK) or propylene glycol monomethyl ether acetate (PMA) / dimethylformamide (DMF) is used. The solvent may be contained in an amount of 1 to 3% by weight.

For example, a film made of such an adhesive is kneaded with a mixture obtained by adding a curing agent, a thermoplastic resin, a polyether-based elastomer, an inorganic insulating filler, an additive, and a solvent to an epoxy resin mixture. The varnish is applied to a release sheet made of polyethylene terephthalate (PET) and dried at a temperature of 60 to 100 ° C. to form a varnish.

The dried film can be easily stored by laminating a polyethylene protective sheet on the upper surface of the film and winding it into a roll. Further, the thickness of this film can be freely set, but is preferably in the range of 20 to 100 μm from the viewpoint of insulation.

Then, this film is pressure-bonded on a desired insulating substrate using a vacuum laminator, and is cured by heating in an oven, whereby an adhesive layer can be formed on the insulating substrate.

Thus, according to the adhesive of the present invention, the heat resistance and the moisture resistance are good, and the elongation change at break after a high-temperature storage test is from -50 to -50 when measured by the method specified in JIS-C-5012. An adhesive with a small value of 50% can be obtained.

It should be noted that the adhesive of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. Contains a hindered phenolic antioxidant to improve the formability, a lubricant of higher fatty acid ester to improve the formability, and an electroless plating catalyst to improve the peel strength of the wiring conductor layer. It is also possible to make it.

Next, an electronic component module using the adhesive of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of an essential part showing an example of an electronic component module when a semiconductor element is mounted as an electronic component on a wiring board using the adhesive of the present invention.

In FIG. 1, reference numeral 1 denotes an electronic component module including a wiring board 2 and electronic components 3. Wiring board 2
Is mainly composed of an insulating substrate 4, an adhesive layer 5, and a wiring conductor layer 6. In this example, the adhesive layer 5
3a of 5a, 5b, 5c on the front surface, and 5d, 5e,
An example in which three layers 5f are formed is shown.

The insulating substrate 4 is made of a resin material such as glass fiber-epoxy resin or glass fiber-bismaleimide triazine resin / glass fiber-allyl-modified polyphenylene ether resin / aramid fiber-epoxy resin. In the present embodiment, a wiring conductor layer 6 made of copper, nickel, gold, or the like is formed on the front and back surfaces of the insulating substrate 4 and a through-hole conductor formed inside a through-hole 10 formed by drilling or the like. 11 is electrically connected. Note that an internal wiring conductor (not shown) may be formed in an inner layer of the insulating substrate 4.

An adhesive layer 5 formed using the adhesive of the present invention is formed on both the front and back surfaces of the insulating substrate 4.
The adhesive layer 5 functions as a support for supporting the electronic component 3 mounted on the wiring board 2.

The adhesive layer 5 has a desired thickness after drying a liquid varnish obtained by kneading a mixture obtained by adding a solvent or the like to the adhesive of the present invention on a polyethylene terephthalate (PET) sheet. Is applied by using a roller coater, dried and cured at a temperature of 60 to 100 ° C. to form a film, and this film is formed by pressing the film on both the front and back surfaces of the insulating substrate 4 with a vacuum laminator.

The surface of the adhesive layer 5 is roughened with a roughening solution to form a rough surface with a myriad of fine holes, so that the adhesion between the adhesive layer 5 and the wiring conductor layer 6 is improved. As a result, the peel strength can be improved, and as a result, the durability can be improved in a reliability test such as a temperature cycle test.

Such a rough surface can be obtained, for example, by bonding the surface of the adhesive layer 5 to a solution containing about 10% of an organic solvent such as glycol ether and about 1% of an alkali such as sodium hydroxide.
After immersion for about 10 minutes to swell the surface of the adhesive layer 5, it is immersed for about 10 minutes in a solution of about 10% of an oxidizing agent such as permanganate to dissolve the thermoplastic resin on the surface of the adhesive layer 5. Finally, the adhesive layer 5 is immersed in a 5% aqueous solution of sulfuric acid for about 5 minutes.
Formed by reducing the surface of

On the surface of the adhesive layer 5, a wiring conductor layer 6 is formed. The wiring conductor layer 6 functions as a conductive path for electrically connecting the electronic component 3 such as a semiconductor element to an external electric circuit board (not shown). Each electrode of the component 3 is electrically connected by a flip chip connection via a conductor bump 9 made of gold, solder, or the like, and the portion exposed on the lower surface of the wiring board 2 is soldered to the wiring conductor layer of the external electric circuit board. Thus, the electronic component 3 is electrically connected to the external electric circuit board via the wiring conductor layer 6.

Such a wiring conductor layer 6 is formed by a subtractive method, an additive method, or the like. Copper is applied to the surface of the roughened adhesive layer 5 by, for example, an electroless plating method. After patterning with photoresist, copper is deposited to a predetermined thickness by electrolytic plating,
Thereafter, a dry film is peeled off and etched to form a wiring pattern. The wiring conductor layer 6 is made of a low-resistance metal such as gold, copper, and nickel. Copper is particularly preferable from the viewpoint of low resistance and low cost.

The thickness of the wiring conductor layer 6 is preferably 3 μm or more from the viewpoint of transmitting a high-speed electric signal. In order to prevent a large stress from remaining in the conductor layer 6 and to make it difficult for the wiring conductor layer 6 to peel off from the adhesive layer 5, it is preferable to set the thickness to 50 μm or less.

Such an adhesive layer 5 and a wiring conductor layer 6
When a plurality of layers are formed on the insulating substrate 4, a plurality of films to be the adhesive layer 5 are formed in advance, and the lamination of the adhesive layer 5 and the formation of the wiring conductor layer 6 may be sequentially performed. .

Further, the plurality of wiring conductor layers 6 are
Are electrically connected by a through conductor 8 attached to an inner wall of a through hole 7 provided in the inside.

The through-hole 7 is formed by a method of exposing and developing by means of an exposure / development method, or by a carbon dioxide laser or YA.
A method of drilling by a laser method such as a G laser or a UV laser is used, but fine processing can be performed without depending on the material of the adhesive layer 5, and the hole diameter of the through hole 7 can be freely set in a range of 10 to 200 μm. It is most preferable to use a carbon dioxide gas laser which can be processed and has a high processing speed.

According to the adhesive of the present invention, the thermoplastic resin constituting the adhesive has a weight average molecular weight of 10,000 to 50,000.
Since the oxygen index is as large as 0 and the oxygen index is small, it is easily decomposed by the heat of the laser, and when the through-hole 7 is formed, the residue of the adhesive does not remain around or inside the through-hole 7.
When the through conductor 8 is formed by plating, the connection reliability can be improved.

The through conductor 8 may be formed by performing plating simultaneously with the wiring conductor layer 6 when the wiring conductor layer 6 is applied by plating. In addition, the through conductor 8 is formed by being adhered to the inner wall surface of the through hole 7.
May be filled with metal by plating.

Further, the electronic component 3 is attached to the outermost adhesive material layer 5.
The electronic component 3 and the wiring conductor layer 6 are electrically connected by connecting the wiring component to the wiring conductor layer 6 formed on the surface thereof via a conductor bump 10 such as solder. By injecting an underfill 12 made of resin between the electronic component 3 and the layer 5, the electronic component 3 is firmly fixed to the surface of the adhesive layer 5.

In the electronic component module 1 of the present invention, the change rate of the elongation at break of the adhesive layer 5 after the high-temperature storage test in the above configuration is -50 to 50 as measured by the method specified in JIS-C-5012. %, The electronic component module 1 has good connection reliability in a thermal fatigue resistance test such as a temperature cycle test and does not cause disconnection when the electronic component 3 is mounted.

The conductor bump 9 has a function of electrically and mechanically connecting the wiring conductor layer 6 and the electronic component 3, and is made of lead-tin, gold, tin-zinc, tin-silver-bismuth, or the like. For example, when the conductive material is lead-tin, the paste prepared using the conductive material is printed at a predetermined location by a screen printing method, and then passed through a reflow furnace to form the wiring conductor layer 6. It is fixedly formed on the surface.

Thus, according to the electronic component module of the present invention, it is possible to obtain an electronic component module that is excellent in thermal fatigue resistance in a temperature cycle test and the like and connection reliability when mounting the electronic component.

It should be noted that the electronic component module of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the wiring board 2 was manufactured by laminating three adhesive layers 5 on each of the front and back surfaces of the insulating substrate 4. However, one, two, or four or more adhesive layers were formed. 5 may be laminated, or the adhesive layer 5 may be laminated only on the front or back surface of the insulating substrate 4. Furthermore, a solder resist layer 13 having the same composition as the adhesive of the present invention may be formed on the wiring conductor layer 6 on the surface of the adhesive layer 5.

Further, a resistor, a capacitor, a piezoelectric element, or the like may be mounted as the electronic component 3 mounted on the electronic component module 1 in addition to the semiconductor element. A radiator plate such as a stiffener may be attached to the wiring board 2 to dissipate heat.

[0068]

EXAMPLES In order to evaluate the characteristics of the adhesive of the present invention and the electronic component module using the adhesive, an electronic component module using the following adhesive film was manufactured. (Adhesive Example 1) As an epoxy resin mixture, a polyfunctional epoxy resin, cresol novolac type epoxy resin, was 60% by weight, a bifunctional epoxy resin, liquid bisphenol A type epoxy was 20% by weight, and a brominated bisphenol A type was used. A mixture consisting of 20% by weight of epoxy was used.
4% by weight of diamino-6- (2-methyl-1-imidazolylethyl) -1,3,5-triazine, 20% by weight of propionate adipic acid having a weight average molecular weight of 120,000 as a thermoplastic resin, polyether type 20% by weight of an epoxy-modified polytetramethylene glycol having a weight average molecular weight of 8000 as an elastomer, 8% by weight of finely divided silica as an inorganic insulating filler, and methyl ethyl ketone (MEK) and dimethylformamide (DMF) as solvents are added and mixed. A varnish-like adhesive was produced.

The varnish-like adhesive was applied on a polyethylene terephthalate (PET) sheet by a roll coater so that the thickness after drying was 45 μm, and then dried at a temperature of 60 to 100 ° C. to obtain an adhesive film (film A). ) Got.
The uncured film A was subjected to a 180-degree bending test for flexibility evaluation, and no abnormality such as a crack was observed in the bent portion.

After the film A was heat-cured at a temperature of 175 ° C. for 3 hours, the elongation at break was 8% when the film was pulled at a rate of 5 mm / minute by a tensile tester. Further, when a heat history of keeping the film A at a temperature of 150 ° C. for 500 hours was added to the film A, the elongation at break was 6%, and the rate of change in elongation at break after the high temperature storage test was −25%. (Embodiment 2 of adhesive) As an epoxy resin mixture, 50% by weight of a cresol novolak type epoxy resin as a polyfunctional epoxy resin, 30% by weight of a liquid bisphenol A type epoxy as a bifunctional epoxy resin, and a brominated bisphenol A type A mixture consisting of 20% by weight of epoxy was used.
3% by weight of diamino-6- (2-methyl-1-imidazolylethyl) -1,3,5-triazine; 30% by weight of butylene adipate having a weight average molecular weight of 200,000 as a thermoplastic resin; A varnish-like adhesive was produced by adding and mixing 30% by weight of an epoxy-modified polyethylene glycol having a weight average molecular weight of 5000 as an elastomer, 5% by weight of finely divided silica as an inorganic insulating filler, and MEK and PMA as a solvent.

The varnish adhesive was applied on a PET sheet by a roll coater so that the thickness after drying was 30 μm, and then dried at a temperature of 60 to 100 ° C. to obtain an adhesive film (film B). . The uncured film B was subjected to a 180-degree bending test to evaluate the flexibility, but no abnormality such as a crack was observed in the bent portion.

Further, after the film B was heat-cured at a temperature of 175 ° C. for 3 hours, the elongation at break when the film was pulled at a speed of 5 mm / minute by a tensile tester was 9%. Further, when a heat history of holding at a temperature of 150 ° C. for 500 hours was added to the film B, the elongation at break was 8%, and the rate of change in elongation at break after the high-temperature storage test was −11%. (Comparative Example of Adhesive Material) As an epoxy resin mixture, a polyfunctional epoxy resin, cresol novolak type epoxy resin, is 60% by weight, a bifunctional epoxy resin is a liquid bisphenol A type epoxy, 20% by weight, and a brominated bisphenol A type epoxy. Was added to the epoxy resin mixture, and 2% by weight of dicyandiamide as a curing agent, 8% by weight of finely ground silica as an inorganic insulating filler, and MEK and DMF as solvents were added to the epoxy resin mixture. Then, a varnish-like adhesive was produced.

The varnish-like adhesive was applied on a PET sheet by a roll coater so that the thickness after drying was 45 μm, and then dried at a temperature of 60 to 100 ° C. to obtain an adhesive film (film C). . When the uncured film C was subjected to a 180-degree bending test for flexibility evaluation, cracks occurred at the bent portions.

After the film C was heat-cured at a temperature of 175 ° C. for 3 hours, the elongation at break was 5% when the film was pulled at a rate of 5 mm / min by a tensile tester. Further, when a heat history of holding at a temperature of 150 ° C. for 500 hours was added to the film C, the elongation at break was 1%, and the rate of change in elongation at break after the high-temperature storage test was −80%.

As described above, the film produced using the adhesive of the comparative example is inferior in flexibility when uncured, and has a very large elongation change at break of -80% after a high temperature storage test. Was.

On the other hand, a film produced using the adhesive of the present invention has excellent flexibility when uncured, and has a 150 ° C.
Even when a heat history of holding at a temperature of 500 hours was added, it was confirmed that the film had a small value of a change in elongation at break after a high temperature storage test of -25 to -11%. (Embodiment 1 of electronic component) Film A was simultaneously laminated on both sides of an insulating substrate made of glass fiber-epoxy resin by a vacuum laminator.
The ET film was peeled off, and then heat-cured at a temperature of 175 ° C. for 1 hour, a through-hole was formed with a carbon dioxide laser, and then roughened with a potassium permanganate solution,
After treatment with a palladium-based plating catalyst, electroless copper plating was performed, and further, wiring pattern processing was performed with a dry film photoresist, and a wiring conductor layer having a thickness of 18 μm was formed by electrolytic copper plating. At that time, the peel strength of the wiring conductor layer was 0.8 kg / cm.

Then, in order to stabilize the peel strength
Heating is performed at 175 ° C for 2 hours, and the lamination of film A and the formation of the wiring conductor layer and the through conductor by plating, roughening, and plating are repeated several times, and the adhesive layer and the wiring of the six layers are formed. After forming the conductor layer on the insulating substrate, apply nickel and gold plating on the solder resist processed pad,
Next, solder bumps were formed. Further, after mounting a semiconductor element on the solder bumps of the wiring board and electrically connecting the semiconductor element through a reflow furnace, an underfill material is injected into a gap between the semiconductor element and the wiring board, and an electronic component module A for reliability evaluation is formed. I got

Next, using this sample, a temperature cycle test was performed as a reliability test, and the electronic component module A was evaluated based on the appearance of the wiring board such as cracks, swelling and peeling, and the value of the resistance value change rate. .

For the temperature cycle test, a gas phase cooling / heating tester was used. Samples were placed in a gas phase at a temperature of −60 ° C. and 150 ° C., respectively.
The test was allowed to stand for 0 minute, and this was regarded as one cycle, and an evaluation test was performed under the condition of 2000 cycles. The rate of change in resistance was calculated by measuring the resistance before and after the test.

As a result, the electronic component module A of the present invention
No cracks occurred even after 2000 cycles of the temperature cycle test, and the rate of change in the resistance value was as low as 5%, indicating that the electronic component module had a good connection between the semiconductor element and the wiring board by the solder bumps. (Embodiment 2 of electronic component) Film B was simultaneously laminated on both front and back sides of an insulating substrate made of glass fiber-epoxy resin by a vacuum laminator.
The ET film was peeled off, and then heat-cured at a temperature of 175 ° C. for 1 hour, and then a through-hole was formed with a carbon dioxide gas laser. Then, roughening treatment with potassium permanganate solution,
After treatment with a palladium-based plating catalyst, electroless copper plating was performed, and further, wiring pattern processing was performed with a dry film photoresist, and a 20 μm-thick wiring conductor layer was formed by electrolytic copper plating. At that time, the peel strength of the wiring conductor layer was 0.9 kg / cm.

In order to stabilize the peel strength, 17
After performing a heat treatment at a temperature of 5 ° C. for 2 hours, the lamination of the film B and the formation of the wiring conductor layer and the through conductor by the drilling of the through hole, the roughening treatment, and the plating are repeated a plurality of times, and the six adhesive layers are formed. After the wiring conductor layer was formed on the insulating substrate, nickel-gold plating was performed on the solder resist-processed pads, and then solder bumps were formed. Further, after mounting a semiconductor element on the solder bumps of the wiring board and electrically connecting the semiconductor element through a reflow furnace, an underfill material is injected into a gap between the semiconductor element and the wiring board, and an electronic component module B for reliability evaluation is formed. I got

As a reliability test, a temperature cycle test was performed in the same manner as in Example 1. As a result, the electronic component module B of the present invention did not crack even after 2000 cycles of the temperature cycle test, and the rate of change in resistance value was reduced. The value was as low as 3%, which proved that the electronic component module had a good connection between the semiconductor element and the wiring board by the solder bump. (Comparative Example of Electronic Components) Film C was simultaneously laminated on both front and back surfaces of an insulating substrate made of glass fiber-epoxy resin by a vacuum laminator.
The T film was peeled off, and then heat-cured at a temperature of 175 ° C. for 1 hour, and then a through-hole was formed with a carbon dioxide laser. Next, after roughening with a potassium permanganate solution, treating with a palladium-based plating catalyst, performing electroless copper plating, further performing wiring pattern processing with a dry film photoresist, and thickening by electrolytic copper plating. A wiring conductor layer having a thickness of 20 μm was formed. The peel strength of the wiring conductor layer at that time was 0.7 kg / cm.

Further, in order to stabilize the peel strength, 17
After performing heat treatment at a temperature of 5 ° C. for 2 hours, lamination of the film C and formation of a wiring conductor layer and a through conductor by drilling of a through hole, roughening treatment, and plating are repeated a plurality of times to form a six-layer adhesive layer. After the wiring conductor layer was formed on the insulating substrate, nickel-gold plating was performed on the solder resist-processed pads, and then solder bumps were formed. Thereafter, the semiconductor element is mounted on the solder bumps of the wiring board and electrically connected through a reflow furnace. Then, an underfill material is injected into a gap between the semiconductor element and the wiring board, and an electronic component module C for reliability evaluation is formed. I got

As a reliability test, a temperature cycle test was performed in the same manner as in Example 1. As a result, cracks occurred in the electronic component module C after 500 cycles of the temperature cycle test, and the shape of the conductive bumps was changed. It has been found that conduction failure with the wiring board has occurred.

[0085]

According to the adhesive of the present invention, the crosslink density can be increased due to the inclusion of the epoxy resin mixture. As a result, molecular cutting of the resin by heat and intrusion of moisture into the resin can be achieved. And an adhesive having good heat resistance and moisture resistance can be obtained. In addition, the weight average molecular weight is 10
Because it contains 000 to 500,000 thermoplastic resin,
An adhesive having good stretchability and good film formability can be obtained. In addition, it contains a polyether-based elastomer that crosslinks with the epoxy resin, and the polyether bond of this polyether-based elastomer exhibits a softening deterioration property in which the bond is broken by continuing heating, so that this softening Deterioration and curing deterioration caused by the progress of cross-linking by continuing to heat the epoxy resin cancel each other out.
−50 to 50% as measured by the method specified in C-5012
Can be small. In addition, since the polyether-based elastomer has a functional group that crosslinks with the epoxy resin, the epoxy resin and the polyether-based elastomer are covalently bonded, and the bond between the two can be strengthened. Even if stress is concentrated at the joint, no crack is generated, and an adhesive having good thermal fatigue resistance can be obtained.

According to the electronic component module of the present invention, each electrode of the electronic component is electrically connected to the wiring conductor layer formed on the surface of the wiring board using the above-mentioned adhesive material layer through the conductor bump. In addition, an electronic component module having good connection reliability in a thermal fatigue test such as a temperature cycle test and having no disconnection when mounting the electronic component can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a principal part showing an example of an embodiment of an electronic component module when a semiconductor element is mounted as an electronic component on a wiring board using an adhesive of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electronic component module 2 ... Wiring board 3 ... Electronic component 4 ... Insulating substrate 5 ... Adhesive layer 6 ... ... Wiring conductor layer 7... Through hole 8.

Claims (4)

[Claims] 1. An epoxy resin mixture, a curing agent which initiates a curing reaction with the epoxy resin mixture at a temperature of 100 to 200 ° C., and a weight average molecular weight of 10,000 to 500,000
Consisting of a thermoplastic resin, a polyether-based elastomer that crosslinks with an epoxy resin, and an inorganic insulating filler,
The rate of change in elongation at break after high-temperature storage test is JIS-C-501.
2. An adhesive characterized by being -50 to 50% as measured by the method specified in 2. 2. The epoxy resin mixture comprises 20 to 80% by weight of a polyfunctional epoxy resin and 20 to 80% by weight of a bifunctional epoxy resin.
80% by weight, and 2 to 10% by weight of the curing agent, 5 to 30% by weight of the thermoplastic resin, and 10 to 40% by weight of the polyether-based elastomer by external addition to the epoxy resin mixture The adhesive according to claim 1, wherein the inorganic insulating filler is added in an amount of 3 to 10% by weight. 3. The adhesive according to claim 1, wherein the adhesive is in the form of a film. 4. An insulating substrate, an adhesive layer formed on the insulating substrate by using the adhesive according to claim 1, and each of the insulating substrate and the adhesive layer A wiring board formed of a plurality of wiring conductor layers formed on the surface and a through conductor formed in a through hole formed in the adhesive layer and electrically connecting the plurality of wiring conductor layers to each other. An electronic component module having components mounted thereon,
An electronic component module, wherein the wiring conductor layer formed on the surface of the wiring board and each electrode of the electronic component are electrically connected via a conductor bump.