JP2005281509A - Curable resin composition and metal base circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-based circuit substrate, excellent in close adhesion of the metal plate with an electroconductive circuit, also excellent in stress-relaxation property, without forming abnormality such as crack formation at solder or its vicinity even on getting a rapid heating/cooling, and excellent in heat resistance, heat-radiating property and further moisture resistance. <P>SOLUTION: This metal-based circuit substrate installed with a circuit mediated through an insulating layer on at least one main surface of the metal plate is characterized by using a cured material of the curable resin composition consisting of (1) an adhesive resin consisting of an addition reaction type silicone resin, (2) a curing accelerator having a silicone skeleton and having at least ≥1 active silyl hydrogen bond in its main chain, and (3) an inorganic filler, and having ≤0.3 GPa storage elastic modulus at (-)40°C, and also ≥0.05 GPa and ≤0.1 GPa at 125°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a metal-based circuit board excellent in stress relaxation properties and excellent in insulation reliability and heat dissipation and a curable resin composition providing the same.

A metal base circuit board that has an insulating layer made of epoxy resin or other resin compounded with an inorganic filler on a metal plate, and a conductive circuit on the insulating layer has excellent heat dissipation. Used as a circuit board for mounting.

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, a metal-based circuit board that is further excellent in heat dissipation has attracted attention.

Conventional metal-based circuit boards often use aluminum plates for heat dissipation and economical reasons. However, when heating / cooling is repeated under actual use, the aluminum plates and electronic components, particularly chip components, are used. A large thermal stress is generated due to the difference in thermal expansion coefficient with respect to the solder, and there is a problem that the electrical reliability is lowered, for example, a crack is generated in the solder portion where the component is fixed or in the vicinity thereof.

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 this purpose, for example, Patent Document 1 discloses a composition having a low elastic modulus with a reactive acrylic rubber, but the heat cycle properties at −40 ° C. and 125 ° C. are still not sufficient.
JP-A-10-242606.

Further, the conventional epoxy resin has a glass transition point, and the change in the storage elastic modulus in the vicinity thereof is remarkable, which is insufficient from the viewpoint of absorbing thermal stress.

Silicone resin can be used as a resin with no glass transition point under heat cycle test conditions, but it has been used practically while having the potential for excellent heat cycle due to poor adhesion and poor fillability. I couldn't.

The present invention has been made in view of the above circumstances, and provides a curable resin compound having a low elastic modulus and excellent in adhesion, heat resistance, and moisture resistance. As a result, a metal plate and a conductive circuit are provided. It has excellent adhesion to the surface, and also has excellent stress relaxation properties, and does not cause abnormalities such as cracking in the solder or its vicinity even when subjected to rapid heating / cooling, excellent heat resistance, heat dissipation, and moisture resistance An object of the present invention is to provide a metal base circuit board.

The present invention includes (1) an adhesive resin comprising an addition reaction type silicone resin, (2) a curing accelerator having a silicone skeleton and having at least one active silyl hydrogen bond in the main chain, and (3) A curable resin composition comprising an inorganic filler.

Further, the present invention is a cured product of the resin composition, wherein the storage elastic modulus is 0.3 GPa or less at −40 ° C. and 0.05 GPa or more and 0.1 GPa or less at 125 ° C. This is a cured product.

Furthermore, the present invention provides a metal base circuit board in which a circuit is provided on at least one main surface of a metal plate via an insulating layer, wherein the insulating layer is made of the hardened body according to claim 2. It is a circuit board.

Since the curable resin composition of the present invention has the characteristics that the cured product has excellent stress relaxation properties and excellent insulation reliability, the metal base circuit board using the cured product is under actual use conditions. It is possible to provide a highly reliable hybrid integrated circuit without causing cracks in a solder portion to which a chip is fixed even by a severe temperature change.

In addition, the cured product of the present invention contains an inorganic filler so that the conventional heat dissipating properties are excellent, while the excellent electrical insulation properties such as withstand voltage are maintained in good condition. The metal base circuit board of the present invention using the stress relaxation property can be used in a harsh environment such as an automobile engine room, and is very useful industrially.

The curable resin composition of the present invention comprises (1) an adhesive resin composed of an addition reaction type silicone resin, and (2) a curing acceleration having a silicone skeleton and having at least one active silyl hydrogen bond in the main chain. And (3) a curable resin composition comprising an inorganic filler.

Various types of silicone resins are known, such as condensation types that produce alcohol and acetic acid. In the electrical and electronic field, which is the application field of the invention, swelling during pressing due to the generation of gas, wiring due to acid, etc. An addition reaction type adhesive is preferably selected because there is no fear of corrosion of the material.

Specific examples of the addition reaction type liquid silicone resin include one-part silicone resin having both a vinyl group and an H-Si group in one molecule, an organopolysiloxane having a vinyl group at the terminal or side chain, and a terminal or Two-part silicone resins such as organopolysiloxanes having two or more H-Si groups in the side chain can be mentioned. Commercial products of such addition reaction type liquid silicone resins include, for example, GE Toshiba Silicone. For example, trade names “TSE3033, XE14-C0914” (hereinafter abbreviated as “XE-14”) and the like can be exemplified.

In addition, the essence of the present invention is to apply a curing accelerator having a specific composition to the adhesive resin having the specific composition, and further blend an inorganic filler. That is, the curing accelerator has a function of accelerating the curing of the adhesive resin, and can greatly change the properties of the cured body obtained depending on the type and amount thereof. The flexibility of the cured body of the adhesive resin varies depending on the crosslink density formed by vulcanization, but the curing accelerator has a feature that can exactly control the crosslink density. Furthermore, the curing accelerator has the effect that the interfacial adhesion can be extremely enhanced by reacting with a hydroxyl group generally present on the surface of the inorganic filler in the presence of the inorganic filler described later. Have.

As the curing accelerator, a curing accelerator having a silicone skeleton and having at least one active silyl hydrogen bond in the main chain is selected according to the results of the study of the present inventors. GE Toshiba Silicone, trade name “TC-25B”, Toray Dow Corning trade name “RD-1” can be mentioned.

As the inorganic filler that can be used in the present invention, those having good electrical insulation and high thermal conductivity are used. Such as aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), silicon nitride (Si ₃ N ₄ ), boron nitride (BN), silica (SiO ₂ ), etc. Can be used. Of these, aluminum oxide is preferable because it can be easily obtained at a low cost because it has a spherical particle shape and can be highly filled. Examples of this include “DAW-10” manufactured by Denki Kagaku Kogyo Co., Ltd. and “AO-802” manufactured by Admatechs.

In a preferred embodiment, the cured product of the curable resin composition of the present invention has a storage elastic modulus at −40 ° C. of 0.3 GPa or less, preferably 0.27 GPa or less, and a storage elastic modulus at 125 ° C. It is 0.05 GPa or more and 0.1 GPa or less, preferably 0.07 GPa or less and 0.06 GPa or more.

When the curable resin composition of the present invention is applied to a metal base circuit board, the thickness of the insulating layer after curing is determined in consideration of stress relaxation, heat dissipation, insulation reliability, productivity, etc. Usually, it is about 50 to 150 μm.

As a conductor circuit used as a metal base circuit board, any of copper, aluminum, nickel, iron, tin, silver, titanium, an alloy containing two or more of these metals, or a clad foil using the metal or alloy, etc. Can be used. The foil manufacturing method may be an electrolytic method or a rolling method, and the foil may be plated with a metal such as Ni plating, Ni-Au plating, or solder plating. From the viewpoint of adhesion to the layer, the surface of the conductor circuit on the side in contact with the insulating adhesive layer is more preferably roughened in advance by etching, plating or the like.

The metal plate used for the metal base circuit board is made of aluminum, iron, copper and alloys thereof, or clad materials thereof, and the thickness of the metal plate is not particularly specified, but it is rich in heat dissipation and economical. Therefore, aluminum having a thickness of 0.5 to 5.0 mm is generally selected.

In addition, regarding the manufacturing method of the metal base circuit board of the present invention, an insulating material obtained by appropriately adding an additive such as an antifoaming agent or a leveling agent to the curable resin composition is applied on the metal plate and / or the conductive foil, A method of forming a circuit from the conductor foil after the conductor foil or the metal plate is sufficiently cured, or a sheet made of an insulating material in advance, and attaching the metal plate and the conductor foil through the sheet It can be obtained by a conventionally known method such as a method of forming a circuit or a method of directly using a conductor circuit formed in advance in place of the conductor foil in the above method.

Hereinafter, based on an Example, this invention is demonstrated still in detail.

(Example 1) An equal amount of XE-14 agent A and agent B was mixed in advance with an electrolytic copper foil of 70 μm, thinly applied to the surfaces to be bonded, and wiped off with a becot. Next, the insulation shown in Table 1 was mixed with a hybrid mixer, applied to an aluminum plate having a thickness of 2 mm, dried to a thickness of 70 μm, and dried in an oven at 80 ° C. for 20 minutes.

The copper foil was laminated and pressed by a vacuum press at a pressing pressure of 30 kg / cm ² at 80 ° C. for 30 minutes, 100 ° C. for 30 minutes, and 150 ° C. for 60 minutes to obtain a substrate for a metal base circuit board. In addition, when the hardening body was created on the same conditions as the above and the storage elastic modulus was measured, it was 0.27 GPa at -40 degreeC, and was 0.06 GPa at 125 degreeC.

(Example 2) XE-14 A agent B agent was mixed in an equal amount to an electrolytic copper foil of 70 μm in advance, thinly applied to the surface to be bonded, and wiped off with a becot. Next, the insulating agent having the composition shown in Table 2 was mixed with a hybrid mixer, applied to a 2 mm thick aluminum plate, dried to 50 μm, and dried in an oven at 80 ° C. for 20 minutes.

Copper foils were bonded together and pressed by a vacuum press at a pressing pressure of 30 kg / cm ² under conditions of 80 ° C. for 30 minutes, 100 ° C. for 30 minutes, and 150 ° C. for 60 minutes to obtain a substrate for a metal base circuit board.

Example 3 A 70 μm electrolytic copper foil was preheated at 300 ° C. for 5 minutes. Next, the insulation shown in Table 3 was mixed with a hybrid mixer, dried on copper foil to a thickness of 100 μm, and dried in a far-infrared furnace at 40 ° C. for 20 minutes.

A metal base circuit board is pressed by pressing a copper foil with an insulating layer and a 2 mm thick aluminum plate under a vacuum press at a pressing pressure of 30 kg / cm ² at 80 ° C. for 30 minutes, 100 ° C. for 30 minutes, and 150 ° C. for 60 minutes. A substrate for was obtained.

(Comparative Example 1) A formulation shown in Table 4 was applied to 75 µm copper foil previously washed with acetone so as to be 100 µm after drying, and dried in an oven at 80 ° C for 20 minutes. The following was pressed in the same manner as in Example 1 to obtain a substrate for a metal base circuit board.

(Comparative Example 2) 100 parts by mass of bisphenol F type epoxy resin (Epicoat 807, epoxy equivalent = 173, manufactured by Japan Epoxy Resin Co., Ltd.) as an epoxy resin, and γ-glycidoxypropylmethyldiethoxysilane (AZ-) as a silane coupling agent 6165, manufactured by Nihon Unicar Co., Ltd.), 5 parts by mass, and 500 parts by mass of alumina (AS-50: manufactured by Showa Denko Co., Ltd.) having an average particle size of 5 μm as an inorganic filler were mixed with a universal mixing stirrer and used as a curing agent. 25 parts by mass of polyoxypropyleneamine (Jefamine T-403, manufactured by Texaco Chemical Co.) and 20 parts by mass of polyoxypropyleneamine (Jephamine D2000, manufactured by Texaco Chemical Co., Ltd.) were blended and mixed.

The above mixture is applied onto an aluminum plate having a thickness of 2.0 mm so that the thickness of the insulating layer after curing is 100 μm, pre-cured to a B stage state, and an electrolytic copper foil having a thickness of 70 μm is pasted with a laminator. Then, after-cure at 80 ° C. × 2 hours and 150 ° C. × 3 hours was performed to produce a substrate for a metal base circuit board.

[Comparative Example 3] 116 parts by mass of hydrogenated bisphenol A type epoxy resin (YX8000, epoxy equivalent = 201, manufactured by Japan Epoxy Resin Co., Ltd.) as an epoxy resin, and γ-glycidoxypropylmethyldiethoxysilane (AZ) as a silane coupling agent -6165, manufactured by Nihon Unicar Co., Ltd.) 5 parts by mass, and 500 parts by mass of alumina (AS-50, Showa Denko Co., Ltd.) having an average particle size of 5 μm as an inorganic filler were mixed with a universal mixing stirrer, and a curing agent was mixed therewith. 25 parts by mass of polyoxypropyleneamine (Jefamine T-403, manufactured by Texaco Chemical Co., Ltd.) and 20 parts by mass of polyoxypropyleneamine (Jefamine D2000, manufactured by Texaco Chemical Co., Ltd.) were mixed and mixed.

The above mixture is applied onto an aluminum plate having a thickness of 2.0 mm so that the thickness of the insulating layer after curing is 100 μm, pre-cured to a B stage state, and an electrolytic copper foil having a thickness of 70 μm is pasted with a laminator. Then, after-cure at 80 ° C. × 2 hours and 150 ° C. × 3 hours was performed to produce a substrate for a metal base circuit board.

About the board | substrate for metal base circuit boards obtained by the said Example and comparative example, the copper foil was etched and the desired circuit which has a pad part was formed, and it was set as the metal base circuit board. Further, the resin composition is cured under conditions of 80 ° C. × 2 hours and 150 ° C. × 3 hours to separately prepare a test piece of a cured product having a thickness of about 100 μm, a width of about 3 mm, and a length of about 50 mm. It used for the measurement of an elasticity modulus. In addition, the cured product is stored elastically in a temperature range of −50 ° C. to + 150 ° C. under a condition of a frequency of 11 Hz and a heating rate of 10 ° C./min using a dynamic viscoelasticity measuring device (manufactured by Rheometrics; RSAIII). The rate was measured. These results are shown in Table 5. Measurement conditions such as withstand voltage are as shown below.

<Withstand voltage> The test piece after treatment for 50 and 100 hours in a pressure cooker tester at a temperature of 121 ° C., a relative humidity of 100% and an atmospheric pressure of 2026 HPa is immersed in insulating oil, and at room temperature between the copper foil and the aluminum plate. An AC voltage was applied, and the voltage at which dielectric breakdown occurred was measured. The initial applied voltage was 0.5 kV. After holding at each voltage for 30 seconds, the voltage was increased stepwise by 0.5 kV and applied with a cutoff current of 2 mA.

<Insulation resistance> It was measured at an applied voltage of 100 V with an Advantest insulation resistance meter R8340.

<Thermal conductivity> It was carried out by the method described in “Monthly Semiconductor World Special Issue” Vol. 4, No. 10, page 59.

<Method for Measuring Copper Foil Peel Strength> Using Tensilon (Orientec Co., Ltd .; Model UCT-1T), the strength when peeled at a rate of 50 mm / min at room temperature in the direction of 90 ° with a width of 1 cm was determined.

<Heat cycle test method> A chip resistor having a chip size of 2.0 mm x 1.25 mm is soldered between pads, and a heat cycle test is performed 5000 times with one cycle of -40 ° C 7 minutes to + 125 ° C 7 minutes. Thereafter, the presence or absence of cracks in the solder portion was observed with a microscope. Those having a crack occurrence of 10% or more in the solder portion were regarded as defective, those having a solder crack occurrence of less than 10% were judged good, and the number of heat cycles at which a good situation could be confirmed was determined.

Since the curable resin composition of the present invention provides a cured product having excellent stress relaxation properties and excellent insulation reliability, the metal base circuit board of the present invention using the same is used under actual use conditions. It is possible to provide a highly reliable hybrid integrated circuit without causing cracks in a solder portion to which a chip is fixed even by a severe temperature change.

In addition, the cured product of the present invention contains an inorganic filler so that the conventional heat dissipating properties are excellent, while the excellent electrical insulation properties such as withstand voltage are maintained in good condition. The stress relaxation property is improved, and the metal base circuit board of the present invention using the stress relaxation property can be used in a harsh environment such as an automobile engine room, and is very useful in industry. .

Claims (3)

(1) an adhesive resin composed of an addition reaction type silicone resin, (2) a curing accelerator having a silicone skeleton and having at least one active silyl hydrogen bond in the main chain, and (3) an inorganic filler A curable resin composition characterized by comprising: A cured product of the curable resin composition according to claim 1, wherein the storage elastic modulus is 0.3 GPa or less at -40 ° C and 0.05 GPa or more and 0.1 GPa or less at 125 ° C. Hardened body. A metal base circuit board comprising a circuit provided on at least one main surface of a metal plate via an insulating layer, wherein the insulating layer is made of the cured body according to claim 2.