JP4914284B2 - Circuit board composition and circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board excellent in stress relaxation, heat resistance, moisture resistance and heat radiating properties. <P>SOLUTION: The composition for the circuit board comprises an epoxy resin having a polyether skeleton in the main chain, a curing agent having an aromatic ring and &ge;2 primary amino groups on terminals of the main chain and an inorganic filler as essential components. Preferably, the composition for circuit boards includes &ge;1 species epoxy resins selected from a group consisting of high molecular weight epoxy resins having a straight main chain and a bisphenol F type or a bisphenol A type skeleton having 800-4,000 epoxy equivalent, polypropylene glycol type epoxy resins, polyethylene glycol type epoxy resins and polytetramethylene glycol type epoxy resins. More preferably, the resin composition after curing has 100-5,000 MPa storage modulus at 300 K. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a circuit board having excellent stress relaxation and excellent insulation reliability and heat dissipation, particularly a circuit board composition that can easily provide a metal base circuit board and a circuit board using the same.

A circuit board on which a highly heat-generating electronic component is mounted because a metal base substrate having an insulating layer made of an epoxy resin filled with an inorganic filler on a metal plate and a conductive circuit disposed on the insulating layer is excellent in heat dissipation. It is used as.

On the other hand, with respect to in-vehicle electronic devices, there is a demand for arranging the electronic devices in the engine room together with downsizing and space saving. The engine room has a harsh 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, the metal base circuit board having excellent heat dissipation has attracted attention.

Conventional metal base circuit boards often use an aluminum plate as a metal substrate for heat dissipation and economical reasons. However, when overheating / cooling is repeated under actual use, the aluminum board is mounted on the circuit board. Due to the difference in coefficient of thermal expansion between the electronic parts, especially chip parts, a large thermal stress is generated, and the electrical reliability is reduced, for example, cracks are generated in or near the solder parts fixing the parts. There is a problem. In order to improve such points, it is necessary to make the insulating layer have a high thermal conductivity, a low elastic modulus, and a high level of heat resistance and moisture resistance. For this reason, for example, Patent Document 1 discloses a composition having a low elastic modulus with a reactive acrylic rubber, but the moisture resistance is not sufficient. Patent Document 2 discloses a curable resin composition having a low elastic modulus that clears 500 heat cycle tests, but is still insufficient for practical use, and a higher level heat cycle. Characteristics are needed.

JP-A-10-242606 JP 2002-012653 A

The present invention has been made in view of the above circumstances, and provides a composition comprising a curable resin containing an inorganic filler that has a low elastic modulus and is excellent in adhesiveness, heat resistance, and moisture resistance. As its use, it has excellent adhesion between the metal plate and the conductive circuit, excellent stress relaxation, and does not cause abnormalities when cracks occur in the solder or in the vicinity even when subjected to rapid heating / cooling, heat resistance, moisture resistance It is another object of the present invention to provide a circuit board excellent in heat dissipation and, in particular, a metal base circuit board.

The present invention includes (1) an epoxy resin in which the main chain has a polyether skeleton and is linear, (2) a curing agent having an aromatic ring and having two or more primary amine groups at the ends of the main chain, And (3) a circuit board composition comprising an inorganic filler as an essential component, preferably a bisphenol F type or bisphenol A type having an epoxy resin having a linear main chain and an epoxy equivalent of 800 to 4000 A circuit board composition comprising one or more selected from the group consisting of a high molecular weight epoxy resin having a skeleton, a polypropylene glycol type epoxy resin, a polyethylene glycol type epoxy resin, and a polytetramethylene glycol type epoxy resin, and Preferably, in the above circuit board composition, the storage elastic modulus of the cured resin composition is 100 to 5000 MPa at 300K. That. Moreover, this invention is a circuit board using the said composition for circuit boards, Preferably it is a metal base circuit board.

Since the circuit board composition of the present invention and the circuit board using the composition are excellent in stress relaxation and insulation reliability, the electronic circuit such as a semiconductor chip can be subjected to severe temperature changes under actual use conditions. It is possible to provide a highly reliable hybrid integrated circuit without causing a crack in a solder portion to which a component is fixed.

The composition for a circuit board of the present invention comprises (1) a linear epoxy resin having a polyether skeleton and (2) an aromatic ring, and 2 primary amine groups at the ends of the main chain. Since a hardener having at least one and (3) an inorganic filler are contained as essential components, a cured product suitable for use in a circuit board excellent in stress relaxation, heat dissipation, heat resistance, and moisture resistance is provided. be able to.

(1) As for the epoxy resin whose main chain has a polyether skeleton and is linear, for example, a polysulfide-modified epoxy resin and a bisphenol A alkylene oxide adduct type epoxy resin are used, and a plurality of these are used in combination. You can also.

Further, (1) For an epoxy resin in which the main chain has a polyether skeleton and is linear, the main chain is linear and has an bisphenol F type or bisphenol A type skeleton having an epoxy equivalent of 800 to 4000. One or more selected from the group consisting of a high molecular weight epoxy resin, a polypropylene glycol type epoxy resin, a polyethylene glycol type epoxy resin, and a polytetramethylene glycol type epoxy resin imparts flexibility to the resin cured product, and its resin composition A circuit board using an object is preferably used because it has excellent stress relaxation properties.

As for the above-mentioned epoxy resin, an epoxy resin having a bisphenol F type or bisphenol A type skeleton having an epoxy equivalent of less than 800 or a hydrogenated bisphenol A type epoxy resin is 10 mass percent or more and 50 mass% in the total epoxy resin. When included below, the balance between the stress relaxation property and moisture resistance of the cured product is further improved, which is preferable.

A curing agent having an aromatic ring and having two or more primary amine groups at the end of the main chain in view of making the balance of electrical insulation and moisture resistance of the cured product of the composition suitable. Selected. Examples of the curing agent having an aromatic ring and having two or more primary amine groups at the end of the main chain include diaminodiphenylmethane, diaminodiphenylsulfone, and metaphenylenediamine.

As for the compounding quantity of a hardening | curing agent, 10-25 mass parts is preferably selected with respect to 100 mass parts of epoxy resins. If it is 25 or less, the stress relaxation property is sufficient, and if it is 10 or more, the insulation reliability and moisture resistance are sufficient. 15-20 mass parts is more preferable.

Inorganic fillers have good electrical insulation and high thermal conductivity, such as aluminum oxide (alumina), aluminum nitride, silicon nitride, boron nitride, and silicon oxide (silica). , One or more of the above can be used. Among these, aluminum oxide and silicon oxide are preferable because those having a spherical particle shape and capable of being highly filled are inexpensive and easily available.

As for the compounding quantity of an inorganic filler, 420-630 mass parts is preferable with respect to 100 mass parts of epoxy resins. If it is 630 or less, the stress relaxation property is sufficient, and if it is 420 or more, the heat dissipation property is sufficient. 480-580 mass parts is more preferable.

When it is added to an epoxy resin to form a circuit board composition, an insulating layer made of a cured product of the circuit board composition is blended into the composition with a silane coupling agent such as epoxysilane or aminosilane. Adhesion with the circuit can be improved.

The storage elastic modulus of the circuit board composition after curing is preferably 100 to 5000 MPa at 300K. Sufficiently satisfactory stress relaxation is obtained at 5000 MPa or less. In addition, if the storage elastic modulus is too low, it may be deformed when external force is applied and the insulation reliability may be impaired.

When the composition of the present invention is applied to a circuit board, the thickness after curing is determined in consideration of stress relaxation, heat dissipation, insulation reliability, productivity, etc., but is usually about 50 to 150 μm. .

The circuit board of the present invention uses the composition for a circuit board. An example of producing a metal base circuit board will be described below.

The metal base circuit board has a structure in which a circuit is provided on a metal plate through an insulating layer made of a cured product of the circuit board composition. The metal plate is made of aluminum, iron, copper, an alloy thereof, or a clad material thereof, and the thickness thereof is not particularly specified. However, since the metal plate is rich in heat radiation and economical, it has a thickness of 0. Aluminum of 5 to 5.0 mm is generally selected. As the circuit, any one of copper, aluminum, nickel, iron, tin, silver, and titanium, an alloy containing two or more of these metals, or a clad foil using an earlier metal or alloy can be used. The foil manufacturing method may be either electrolytic or rolling, and the foil may be plated with a metal such as Ni plating, Ni-Au plating, or solder plating. From the viewpoint of adhesiveness to the layer, it is more preferable that the surface on the side in contact with the insulating layer of the circuit is roughened in advance by etching, plating or the like.

The metal base circuit board is obtained by applying an insulating material obtained by appropriately adding an additive such as an antifoaming agent or a leveling agent to the circuit board composition on the metal plate and / or the metal foil. It can be obtained by a conventionally known method such as a method of sufficiently curing after bonding and forming a circuit from the metal foil, or a method of directly using a circuit in which a circuit is previously formed in place of the metal foil. it can.

[Example 1]
30 parts by mass of a polymer bisphenol F type epoxy resin (manufactured by Japan Epoxy Resin, “Epicoat 4004P”; epoxy equivalent = 848) and 50 parts by mass of a polypropylene glycol type epoxy resin (manufactured by Toto Kasei Co., Ltd., “PG207GS”) Bisphenol F type epoxy resin (Japan Epoxy Resin, “Epicoat 807”; epoxy equivalent = 175) 20 parts by mass, silane coupling agent, γ-glycidoxypropyltrimethoxysilane (manufactured by Toray Dow Corning, “ Z6040N ") 5 parts by mass, aluminum oxide of spherical coarse particles having an average particle size of 16 μm as inorganic filler (“ AS30-1 ”, manufactured by Showa Denko KK) and aluminum oxide of spherical fine particles having an average particle size of 0.7 μm ("AKP-15" manufactured by Sumitomo Chemical Co., Ltd.) 5 0 parts by weight (spherical particles and the spherical fine particles mass ratio of 6: 4), aromatic amines (Nippon Synthetic Chemical Co., Ltd., "Accession Mex H-84B") to 20 parts by mass, were mixed as a curing agent.

The mixture obtained by the above operation was applied to an aluminum plate having a thickness of 2.0 mm so that the thickness of the insulating layer after curing was 100 μm, pre-cured to a B stage state, and an electrolytic copper foil having a thickness of 70 μm using a laminator. And after-curing to produce a copper foil substrate, and further etching the copper foil to form a desired circuit having a pad portion to obtain a metal base circuit board. Moreover, the said mixture was hardened and the test piece of the hardening body about thickness 0.5mm width about 3mm length 50mm was produced separately. The metal base circuit board and the cured body were used for the following test. The results are shown in Table 1.

<Measurement of storage modulus>
About the cured body, using a dynamic viscoelasticity measuring device (manufactured by T & A Instruments, “RSA 3”), in a temperature range of −50 ° C. to + 150 ° C. under conditions of a frequency of 10 Hz and a heating rate of 10 ° C./min. The storage modulus was measured.

<Measurement of withstand voltage>
The circuit board was immersed for 96 hours in a pressure cooker tester at a temperature of 121 ° C., a relative humidity of 100%, and an atmospheric pressure of 2026 hPa for 96 hours, and the voltage before dielectric breakdown was measured. The initial applied voltage was 0.5 kV, and each voltage was held for 30 seconds, and then applied by a method in which the voltage was increased stepwise by 0.5 kV.

<Heat cycle test method>
The circuit board was soldered with a chip resistor having a chip size of 2.0 mm × 1.25 mm between the pads, subjected to 2000 heat cycle tests with -40 ° C. 7 minutes to + 125 ° C. 7 minutes as one cycle, and then a microscope. Then, the presence or absence of cracks in the solder portion was observed. Those having a crack occurrence of 10% or more in the solder part were judged as defective, and those having a solder crack occurrence of less than 10% were judged good.

[Example 2]
30 parts by mass of polymer bisphenol F type epoxy resin (manufactured by Japan Epoxy Resin, “Epicoat 4004P”) and 50 parts by mass of polytetramethylene glycol type epoxy resin (manufactured by Sakamoto Pharmaceutical Co., Ltd., “SR-PTMG”) as epoxy resins The test was conducted in the same manner as in Example 1 except that. The results are shown in Table 1.

Example 3
As an epoxy resin, 30 parts by mass of a polymer bisphenol F type epoxy resin (manufactured by Toto Kasei Co., Ltd., “YD6020”; epoxy equivalent = 3020), 50 parts by mass of a polypropylene glycol type epoxy resin (manufactured by Toto Kasei Co., Ltd., “PG207GS”), hydrogen The test was conducted in the same manner as in Example 1 except that 20 parts by mass of the added bisphenol A type epoxy resin (Dainippon Ink & Chemicals, “EXA-7015”; epoxy equivalent = 207) was used. The results are shown in Table 1.

Example 4
As an epoxy resin, 30 parts by mass of a polymer bisphenol F type epoxy resin (manufactured by Toto Kasei Co., Ltd., “YD6020”), a polytetramethylene glycol type epoxy resin (manufactured by Sakamoto Pharmaceutical Co., Ltd., “SR-PTMG”), 50 parts by mass The test was conducted in the same manner as in Example 1 except that 20 parts by mass of the added bisphenol A type epoxy resin (Dainippon Ink & Chemicals, "EXA-7015") was used. The results are shown in Table 1.

[Comparative Example 1]
As an epoxy resin, 60 parts by mass of a bisphenol F type epoxy resin (manufactured by Japan Epoxy Resin, “Epicoat 807”), a dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink and Chemicals, “HP-7200”; epoxy equivalent = 260) ) 40 parts by mass, silane coupling agent, 5 parts by mass of γ-glycidoxypropylmethylethoxysilane (Nihon Unicar Co., Ltd., “AZ-6165”), alumina having an average particle size of 5 μm as an inorganic filler (manufactured by Showa Denko KK "AS-50") 500 parts by mass, as a curing agent, 20 parts by mass of polyoxypropyleneamine (Mitsui Chemicals Fine, "Jeffamine D230"), polyoxypropyleneamine (Mitsui Chemicals Fine, "Jefamine D2000") ] 25 parts by mass, aromatic amine (manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Mex H-84B ") The test was conducted in the same manner as in Example 1 except that 20 parts by mass was used. The results are shown in Table 1.

[Comparative Example 2]
As an epoxy resin (Japan Epoxy Resin, “Epicoat 807”) 100 parts by mass, γ-glycidoxypropylmethylethoxysilane (Nihon Unicar, “AZ-6165”) 5 parts by mass, Alumina (Showa Denko) , “AS-50”) and 500 parts by mass, and 30 parts by mass of an aromatic amine (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., “Acmex H-84B”) as a curing agent. The results are shown in Table 1.

The substrates obtained in Examples 1 to 4 had low storage elastic modulus, good heat cycle test results, and good withstand voltage after PCT treatment. In Comparative Examples 1 and 2, the withstand voltage after the PCT treatment was good, but since the storage elastic modulus was high, a sufficient stress relaxation effect could not be obtained and the heat cycle test result was poor.

Since the circuit board composition of the present invention and the circuit board using the same are excellent in stress relaxation and insulation reliability, the chip is fixed even by severe temperature changes under actual use conditions. Therefore, it is possible to provide a highly reliable hybrid integrated circuit without causing cracks in the soldered portion. Therefore, the present invention can be used in a harsh environment such as an engine room of an automobile, and is very useful industrially.

Claims (4)

(1) an epoxy resin in which the main chain has a polyether skeleton and is linear, (2) a curing agent having an aromatic ring and having two or more primary amine groups at the ends of the main chain, and (3) A circuit board composition comprising an inorganic filler as an essential component ,
And an epoxy resin having a bisphenol F type or bisphenol A type skeleton having an epoxy equivalent of less than 800 or a hydrogenated bisphenol A type epoxy resin, and
The circuit board composition, wherein the epoxy resin (1) is at least one selected from the group consisting of a polypropylene glycol type epoxy resin, a polyethylene glycol type epoxy resin, and a polytetramethylene glycol type epoxy resin . 2. The circuit board composition according to claim 1 , wherein the cured resin composition has a storage elastic modulus of 100 to 5000 MPa at 300K. Circuit board made by using the composition according to claim 1 or 2. 4. The circuit board according to claim 3 , wherein the circuit board is a metal base circuit board.