JP5516190B2 - Resin composition, metal foil with resin, and metal base substrate - Google Patents

Description

The present invention relates to a resin composition, a metal foil with a resin, and a metal base substrate.

Highly heat-generating electronic components are mounted on a metal plate with an insulating layer made of a resin such as an epoxy resin mixed with an inorganic filler and a conductive circuit on the insulating layer. It is used as a circuit board.

On the other hand, with respect to in-vehicle electronic devices, it is desired to install the electronic devices in the engine room together with downsizing and space saving. The engine room has a severe environment such as a high temperature and a large temperature change, and a substrate having a large heat radiation area is required. For such applications, metal base substrates that are further excellent in heat dissipation have attracted attention.

Conventional metal base substrates often use an aluminum plate for heat dissipation and economical reasons. However, when heating / cooling is repeated under actual use, heat between the aluminum plate and electronic components, particularly chip components, is often used. A large thermal stress is generated due to the difference in expansion coefficient, and there is a problem that the electrical reliability is lowered, for example, a crack is generated at or near the solder portion fixing the component.

In order to improve such a point, it is necessary that the insulating layer has a high thermal conductivity, a low elastic modulus, and a higher level of heat resistance and moisture resistance. For such purposes, resin compositions having a low elastic modulus by using acrylic rubber have been disclosed (for example, Patent Documents 1 and 2).
However, when acrylic rubber is used, there is a problem that sufficient performance cannot be obtained in the heat cycle test.

In addition, as another means for reducing the elastic modulus, a technique using a silicone resin or the like has been studied (for example, Patent Document 3).
However, when silicone resin is used, the adhesion to the metal plate is inferior, so the adhesion to the metal base plate is reduced, and there is a problem that the insulation resistance value is reduced due to moisture absorption between the metal plate and the insulating resin. It was.

Japanese Patent Laid-Open No. 9-8426 JP-A-10-242606. JP 2005-281509 A

  The present invention has been made in view of the above circumstances, and provides a resin composition, a metal with resin, and a metal base substrate that are excellent in adhesion to a metal base plate and heat cycle, and have sufficient insulation resistance. To do.

The object of the present invention is achieved by the present invention described in the following items [1] to [4].
[1] Resin composition comprising (A) phenoxy resin having bisphenol S skeleton, (B) at least one inorganic filler selected from aluminum hydroxide and magnesium hydroxide , and (C) silane coupling agent as essential components A resin composition, wherein (C) the silane coupling agent is 2 to 10% by weight of the total resin composition.
[2] The resin composition according to [1], wherein the content of the phenoxy resin having the (A) bisphenol S skeleton is 10 to 40% by weight of the entire resin composition .
[3] The resin composition according to [1] or [2] is a resin composition further comprising (D) a bisphenol A type epoxy resin .
[4] A metal base substrate using the resin composition according to any one of [1] to [3], a metal, an adhesive layer, and a metal plate.

The resin composition of this invention has sufficient insulation resistance which is excellent in adhesiveness with a metal base board, and heat cycle property.

The resin composition of the present invention will be described.
The resin composition of the present invention is a resin composition comprising (A) a phenoxy resin having a bisphenol S skeleton (B) an inorganic filler and (C) a silane coupling agent as essential components, and (C) a silane cup It is a resin composition characterized in that the ring agent is 2 to 10% by weight of the entire resin composition.
Thereby, it has sufficient insulation resistance which is excellent in adhesiveness with a metal base board, and heat cycle property.
Moreover, since the resin composition of this invention is excellent in adhesiveness with a metal plate, it shows favorable insulation resistance in a long-term insulation reliability test, and has insulation reliability.

In addition, the resin composition of the present invention maintains an excellent point such as a conventional heat dissipating property and an excellent electrical insulation property such as a withstand voltage by including an inorganic filler. However, the stress relaxation property is improved.

The (A) phenoxy resin having a bisphenol S skeleton (hereinafter sometimes simply referred to as “(A) phenoxy resin”) is particularly a compound having a diphenylsulfone structure in the structure of (A) phenoxy resin. It is not limited. It can be obtained by reacting a compound having two epoxy groups in the molecule with bis (4-hydroxyphenyl) sulfone. For example, a phenoxy resin obtained by reacting bisphenol A type epoxy resin and bis (4-hydroxyphenyl) sulfone, a phenoxy resin obtained by reacting biphenyl type epoxy resin and bis (4-hydroxyphenyl) sulfone, a naphthalene type epoxy resin and bis ( And phenoxy resin reacted with 4-hydroxyphenyl) sulfone.

(A) By including the phenoxy resin in the resin layer, not only the adhesion between the resin layer and the metal plate is improved, but also the fluidity is improved at the time of pressing, and it becomes possible to mold without voids. Further, due to the metal atom interaction between the S atom in the molecule and the metal plate, the adhesion between the resin layer and the metal plate is improved, so that the insulation resistance value after moisture absorption is excellent. In addition, the elastic modulus can be reduced, and when used for a metal base substrate, it has excellent stress relaxation properties.For example, when a semiconductor device using a metal base substrate and mounting an electronic component or the like is manufactured, the semiconductor device Even under the heating / cooling environment, no defects such as cracks occur at or near the solder joint where the electronic component and the metal base substrate are joined.

The weight average molecular weight of (A) phenoxy resin is not particularly ^{limited, 3.0 × 10 4 ~4.5 × 10} 4 are preferable. If it is less than 3.0 × 10 ⁴ , it is difficult to lower the elastic modulus, and when used in a semiconductor device, cracks may occur at or near the solder joints under rapid heating / cooling. If the weight average molecular weight is greater than 4.5 × 10 ⁴ , the viscosity of the resin composition increases, fluidity during pressing deteriorates, voids may occur, and the insulation reliability of the metal base substrate decreases. There is a case.

Although content of the said (A) phenoxy resin is not specifically limited, It is preferable that it is 10 to 40 weight% of the whole resin composition. If it is less than 10% by weight, the elastic modulus may not be sufficiently lowered. If it is used for a metal base substrate, the stress relaxation property is not sufficient, and cracks in the solder or its vicinity even when subjected to rapid heating / cooling. May occur. If it exceeds 40% by weight, the fluidity during pressing deteriorates and voids are generated, so that the insulation reliability of the metal base substrate may be lowered.
For example, in the case of a varnish using a solvent or the like, the entire resin composition means a solid excluding the solvent, and liquid components such as a liquid epoxy and a coupling agent are included in the resin composition.

The (B) inorganic filler is not particularly limited, and examples thereof include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, calcium oxide, magnesium oxide, alumina, aluminum nitride, aluminum borate whisker, and nitride. Boron, crystalline silica, amorphous silica, silicon carbide and the like can be mentioned.

Among these, alumina, aluminum nitride, boron nitride, crystalline silica, and amorphous silica are preferable from the viewpoint of high thermal conductivity. More preferred is alumina. When alumina is used, it is preferable in terms of heat resistance and insulation in addition to high thermal conductivity.

Further, from the viewpoint of reliability, crystalline silica or amorphous silica is preferable in that it has few ionic impurities. A metal base substrate having excellent insulation reliability can be manufactured.
Crystalline silica or amorphous silica is suitable in that it has high insulation under a water vapor atmosphere such as a pressure cooker test and has little corrosion on metals, aluminum wires, aluminum plates, and the like.

On the other hand, from the viewpoint of flame retardancy, aluminum hydroxide and magnesium hydroxide are preferred.
Furthermore, for the purpose of imparting melt viscosity adjustment and chicotropic properties, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, crystalline silica, Amorphous silica is preferred.

(B) Content of an inorganic filler is although it does not specifically limit, It is preferable that it is 40 to 70 weight% of the whole resin composition. If the amount is less than 40% by weight, the thermal resistance may increase, and sufficient heat dissipation may not be obtained. If the amount is more than 70% by weight, fluidity during pressing may be deteriorated and voids may be generated. .

By including the (C) silane coupling agent in the resin composition of the present invention, the adhesion to the metal plate is improved, and the insulation reliability of the metal base substrate is improved as compared with the conventional case.
This is presumably due to a synergistic effect of the combination of (A) a phenoxy resin having a bisphenol S skeleton and (B) an inorganic filler.

Although content of the said (C) silane coupling agent is not specifically limited, It is preferable that it is 2-10 weight% of the whole resin composition, and it is more preferable that it is 3-7 weight%. When the content is less than 2% by weight, the adhesion to the metal plate is lowered, and the solder heat resistance may be lowered. On the other hand, if it exceeds 10% by weight, the silane coupling agent may be hydrolyzed and solder heat resistance may be lowered.

The resin composition may further use an epoxy resin as a modifier in the present invention such as an epoxy resin. By adding an epoxy resin, the moisture resistance and heat resistance of the resin composition, particularly the heat resistance after moisture absorption is improved. The epoxy resin is not particularly limited as long as it is an epoxy resin having two or more epoxy groups in one molecule. For example, bisphenol A, bisphenol F, biphenyl, novolac, polyfunctional phenol, naphthalene And glycidyl ethers such as alicyclic type and alcohol type, glycidyl amine type and glycidyl ester type, and the like can be used alone or in combination.

Among these, bisphenol A epoxy resins are preferable from the viewpoint of heat resistance, moisture resistance, metal adhesion, and fluidity during press molding, and bisphenol A epoxy resins that are liquid at room temperature are particularly preferable. The bisphenol A epoxy resin that is liquid at room temperature is particularly excellent in fluidity during press molding, and is excellent in compatibility with the phenoxy resin having a bisphenol S skeleton, and the resin composition does not cause phase separation, etc. Excellent.

The resin composition of the present invention may contain an epoxy resin curing agent. Although it does not specifically limit as a hardening | curing agent, For example, an acid anhydride, an amine compound, a phenol compound, etc. are mentioned.

The resin composition of the present invention may use a curing accelerator as necessary. The curing accelerator is not particularly limited, and examples thereof include imidazoles and derivatives thereof, tertiary amines, and quaternary ammonium salts.

The resin composition of the present invention can optionally be used in combination with known thermoplastic resins, elastomers, flame retardants and fillers, dyes, ultraviolet absorbers and the like as necessary.

Next, the metal foil with resin will be described.
The metal foil with a resin using the resin composition described above can be obtained by forming a resin layer made of the resin composition on the metal foil.
First, in order to form a resin layer, the resin composition of the present invention is acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, cyclohexane, heptane, cyclohexane cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, ethylene glycol, Various mixing machines such as ultrasonic dispersion method, high-pressure collision dispersion method, high-speed rotation dispersion method, bead mill method, high-speed shear dispersion method, and rotation and revolution dispersion method in organic solvents such as cellsolve, carbitol, and anisole A resin varnish is prepared by dissolving, mixing, and stirring using the above.

Although content of the resin composition in the said resin varnish is not specifically limited, 45 to 85 weight% is preferable and 55 to 75 weight% is especially preferable.

Next, the resin varnish is coated on a metal foil using various coating apparatuses, and then dried. Alternatively, the resin varnish is spray-coated on the metal foil with a spray device and then dried. A metal foil with a resin can be produced by these methods.
Although the said coating apparatus is not specifically limited, For example, a roll coater, a bar coater, a knife coater, a gravure coater, a die coater, a comma coater, a curtain coater, etc. can be used. Among these, a method using a die coater, a knife coater, and a comma coater is preferable. Thereby, the metal foil with resin which does not have a void and has the thickness of a uniform insulating layer can be manufactured efficiently.

The thickness of the resin layer is preferably in the range of 50 μm to 250 μm. When the thickness is less than 50 μm, it is used for a metal base substrate described below. It cannot be sufficiently relaxed with an insulating adhesive layer.
As a result, when a semiconductor element, a resistor component, or the like is surface-mounted on a substrate, distortion may increase and sufficient thermal shock reliability may not be obtained. When the thickness exceeds 250 μm, the amount of distortion of the surface-mounted portion is small and good thermal shock reliability can be obtained, but since the thermal resistance increases, sufficient heat dissipation cannot be obtained.

The metal foil is not particularly limited. For example, copper and copper-based alloy, aluminum and aluminum-based alloy, silver and silver-based alloy, gold and gold-based alloy, zinc and zinc-based alloy, nickel and nickel-based alloy, tin and tin And metal foils such as iron alloys, iron and iron alloys.
Among these, copper is preferable because the metal foil can be used as a conductor circuit by etching.
From the viewpoint of low thermal expansion, an iron-nickel alloy is preferable.

In addition, the manufacturing method of the metal foil may be one produced by an electrolytic method or a rolling method, and metal plating such as Ni plating, Ni-Au plating, or solder plating may be applied on the metal foil. From the viewpoint of adhesion to the insulating adhesive layer, it is more preferable that the surface of the conductor circuit on the side in contact with the insulating adhesive layer is roughened in advance by etching, plating, or the like.

The thickness of the metal foil is not particularly limited, but is preferably 0.5 μm or more and 105 μm or less. Further, it is preferably 1 μm or more and 70 μm or less, more preferably 9 μm or more and 35 μm or less. If the thickness of the metal foil is less than the above lower limit value, pinholes are likely to occur, and when the metal foil is etched and used as a conductor circuit, plating variations during circuit pattern formation, circuit disconnection, etching solution or desmear solution If the upper limit is exceeded, the thickness variation of the metal foil may increase or the surface roughness variation of the roughened surface of the metal foil may increase.
The metal foil may be an ultrathin metal foil with a carrier foil. The ultrathin metal foil with a carrier foil is a metal foil obtained by laminating a peelable carrier foil and an ultrathin metal foil. Since an ultra-thin metal foil layer can be formed on both sides of the insulating layer by using an ultra-thin metal foil with a carrier foil, for example, when forming a circuit by a semi-additive method, etc. By electroplating the metal foil directly as the power feeding layer, the ultrathin copper foil can be flash etched after the circuit is formed. By using an ultra-thin metal foil with a carrier foil, even with an ultra-thin metal foil having a thickness of 10 μm or less, for example, a reduction in handling properties of the ultra-thin metal foil in a pressing process, and cracking or cutting of the ultra-thin copper foil are prevented. Can do.

Next, the metal base substrate will be described.
The method for producing the metal base substrate according to the present invention is not particularly limited. For example, the metal plate is laminated so that the resin surface of the metal foil with resin is in contact with one surface or both surfaces of the metal plate, and is pressed and heat-cured using a press or the like. Thus, a metal base substrate can be obtained by forming a resin layer.
The metal base substrate can be used by forming a circuit by etching a metal foil.
In the case of a multi-layer, after forming a circuit on the metal base substrate, a metal foil with resin is further laminated, and a circuit is formed by etching in the same manner as described above to obtain a multi-layer metal base substrate.
Note that a solder resist may be formed on the outermost layer, and the connection electrode portion may be exposed so that a semiconductor element or an electronic component can be mounted by exposure and development.

  Although the thickness of the said metal plate is not specifically limited, It is preferable that it is 0.5-5.0 mm in thickness. This is because it is excellent in heat dissipation and economical.

As another method for producing a metal base substrate, there is a method in which the resin varnish is applied to a metal plate, and then a metal foil is laminated and heated and pressurized.
Similarly to the above, a circuit can be formed by etching.

  In the above, after the resin varnish is applied to the metal plate and the resin is cured, the circuit may be formed by electroless plating and electrolytic plating.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example , a reference example, and a comparative example, this invention is not limited to this.

The raw materials used in Examples , Reference Examples and Comparative Examples are as follows.
(1) Phenoxy resin A: Phenoxy resin (YX-8100, manufactured by Mitsubishi Chemical Co., Ltd., weight average molecular weight 380) which is a copolymer of bisphenol S epoxy resin and biphenyl type epoxy resin
00)
(2) Phenoxy resin B: Phenoxy resin which is a copolymer of bisphenol S epoxy resin and bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical Co., Ltd., YPS-007, weight average molecular weight 40000)
(3) Phenoxy resin C: bisphenol A type phenoxy resin (manufactured by Nippon Steel Chemical Co., Ltd., YP-5
0, weight average molecular weight 50000)
(4) Bisphenol A type epoxy resin (made by DIC, 850S, epoxy equivalent 190)
(5) Bisphenol A type epoxy resin (Mitsubishi Chemical, 1001, epoxy equivalent 475)
(6) Dicyandiamide (Degussa)
(7) Phenol novolac resin (DIC, TD-2010, hydroxyl equivalent 105)
(8) 2-Phenylimidazole (manufactured by Shikoku Chemicals, 2PZ)
(9) γ-Glycidoxypropyltritomexisilane (manufactured by Shin-Etsu Silicone, KBM-40
3)
(10) Aluminum hydroxide (Showa Denko, HP-360)
(11) Alumina (manufactured by Denki Kagaku Kogyo, AS-50)
(12) Boron nitride (SPG-3, manufactured by Denki Kagaku Kogyo)
(13) Silicone resin (XE14-A0425 (A) manufactured by Momentive Performers,
Polyalkylalkenylsiloxane)
(14) Silicone resin (XE14-A0425 (B) manufactured by Momentive Performers,
Polyalkyl hydrogen siloxane)

Example 1
(1) Preparation of resin varnish Phenoxy resin having bisphenol S skeleton (Mitsubishi Chemical, YX-8100, weight average molecular weight 38000, copolymer of bisphenol S epoxy resin and biphenyl type epoxy resin) 22.0% by weight, bisphenol Type A epoxy resin (DIC, 850S, epoxy equivalent 190) 10.0% by weight, bisphenol A type epoxy resin (Mitsubishi Chemical, 1001, epoxy equivalent 475) 15.0 % by weight, 2-phenylimidazole (Shikoku Chemicals) 2PZ) 1.0 % by weight, γ-glycidoxypropyltrimethoxysilane (KBM-403 made by Shin-Etsu Silicone) as a silane coupling agent 2.0 % by weight, aluminum hydroxide (Showa Denko, HP-360, particle size) 3.0 [mu] m) is dissolved and mixed with 50.0 wt% in cyclohexanone And stirred using a high speed stirrer, a resin composition was obtained 70% by weight of the varnish on a solids basis.

(2) Preparation of metal foil with resin As the metal foil, a copper foil having a thickness of 70 μm (GTSMP, manufactured by Furukawa Circuit Foil) was used, and a resin varnish was applied to the roughened surface of the copper foil with a comma coater at 100 ° C. Heat drying for 3 minutes at 150 ° C. for 3 minutes to obtain a resin-coated copper foil with a resin thickness of 100 μm.

(3) Production of metal base substrate The resin-coated copper foil and a 2 mm thick aluminum plate were bonded together as a metal plate, and were subjected to a vacuum press at a press pressure of 30 kg / cm ² at 80 ° C. for 30 minutes and 200 ° C. for 90 minutes. A metal base substrate was obtained by pressing.

(Examples 2 to 9, Reference Examples 1 and 2 and Comparative Examples 1 to 6)
A resin varnish was prepared in the same manner as in Example 1 except that a resin varnish was prepared according to the recipes shown in Tables 1 and 2, and a copper foil with a resin and a metal base substrate were prepared.
Moreover, each evaluation of the following was performed about the metal base substrate obtained by each Example , the reference example, and the comparative example. The evaluation results are shown in Tables 1 and 2.

(Evaluation method)
An evaluation method is shown below for each of the above evaluations.

(1) Peel strength A 100 mm × 20 mm test piece was prepared from the metal base substrates obtained in the examples and comparative examples, and the peel strength between the metal base substrate and the resin layer at 23 ° C. was measured.
The peel strength measurement was performed according to JIS C 6481.

(2) Solder heat resistance After the obtained metal base substrate was cut to 50 mm × 50 mm with a grinder saw, a sample in which only 1/4 of the copper foil was left by etching was prepared and evaluated in accordance with JIS C 6481. Evaluation is performed after immersion for 30 seconds in a solder bath at 288 ° C. in the case of no pretreatment, in the case of no pretreatment, and after 121 ° C., 100%, (PCT treatment) for 4 hours. The presence or absence of abnormalities was examined.
Evaluation criteria: No abnormality: Swelling (there is a bulge on the whole)

(3) Insulation resistance measurement The insulation resistance value of the resin layer of the metal base substrate was measured using an insulation resistance measuring instrument.
The measurement was performed by applying an alternating voltage between the copper foil and the aluminum plate at room temperature. The evaluation was performed in two types: measurement without pretreatment, and measurement after 121 ° C., 100%, (PCT treatment) for 96 hours.

(4) Thermal conductivity The density of the obtained metal base substrate was measured by an underwater substitution method, the specific heat was measured by DSC (differential scanning calorimetry), and the thermal diffusivity was further measured by a laser flash method.
And thermal conductivity was computed from the following formula | equation.
Thermal conductivity (W / m · K) = density (kg / m ³ ) × specific heat (kJ / kg · K) × thermal diffusivity (m ² / S) × 1000

(5) Heat cycle test The obtained metal base wiring board was subjected to 5000 heat cycle tests with -40 ° C. 7 minutes to + 125 ° C. 7 minutes as one cycle, and then the presence or absence of cracks in the solder portion with a microscope Was observed. Those having a crack occurrence of 10% or more in the solder portion were judged as defective, and those having a solder crack occurrence of less than 10% were judged good.
Evaluation criteria: Good: Poor (crack generation rate of 10% or more)

From the evaluation results described in Tables 1 and 2, the following can be understood.
In Comparative Example 1 and Comparative Example 2, the solder heat resistance deteriorated.
This is presumably because Comparative Example 1 has a small amount of γ-glycidoxypropyltritomoxysilane, and Comparative Example 2 has a large amount of γ-glycidoxypropyltritomoxysilane.
In Comparative Example 3, the adhesiveness was lowered, and the insulating property of the resin layer after moisture absorption was lowered.
This is presumably because phenoxy resin having a bisphenol S skeleton was not used but bisphenol A type phenoxy resin was used.
In Comparative Example 4, the peel strength was lowered, and the practical level was not reached in the heat cycle test.
This is presumably because no phenoxy resin was used.
Since the comparative example 5 did not use the inorganic filler, the thermal conductivity was not sufficiently reduced.
Comparative Example 6 uses a silicone resin in place of the phenoxy resin having a bisphenol S skeleton. Moisture absorption occurred between the metal plate and the resin, resulting in a decrease in insulation resistance value.
On the other hand, the metal base substrate using the resin composition of the present invention obtained in Examples 1 to 11 and the metal foil foil with resin has high peel strength, excellent solder heat resistance, sufficient insulation resistance, and high. It had thermal conductivity and was a good result in the heat cycle test.
Therefore, it can be seen that a metal base substrate having excellent performance can be obtained by using the resin composition specified in the present invention.

The resin composition, resin-coated metal foil, and metal base substrate of the present invention can be used for substrates used in harsh environments such as automobile engine rooms, and are very useful industrially.

Claims (4)

A resin composition comprising (A) a phenoxy resin having a bisphenol S skeleton, (B) at least one inorganic filler selected from aluminum hydroxide and magnesium hydroxide , and (C) a silane coupling agent as essential components. (C) The resin composition, wherein the silane coupling agent is 2 to 10% by weight of the entire resin composition. 2. The resin composition according to claim 1, wherein the content of the (A) phenoxy resin having a bisphenol S skeleton is 10 to 40% by weight of the entire resin composition . The resin composition according to claim 1 or 2, further comprising (D) a bisphenol A type epoxy resin . A metal base substrate using the resin composition according to any one of claims 1 to 3, a metal, an adhesive layer, and a metal plate.