JP2003238767A - Resin composition, resin-clad metal foil, and multilayer printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a resin composition excellent in dielectric characteristics, heat resistance and flame retardancy, and to provide a resin-clad metal foil and a printed wiring board. <P>SOLUTION: The resin composition is the one which constitutes an insulation layer of the resin-clad metal foil and comprises a novolak cyanate resin and a bismaleimide compound. The resin-clad metal foil is obtained by applying the above resin composition onto a metal foil. The multilayer printed circuit board is obtained by laying the above resin-clad metal foil on one or both faces of an inner layer circuit board and then by applying heat and pressure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition, a resin-coated metal, and a multilayer printed circuit board.

[0002]

2. Description of the Related Art In recent years, portable electronic devices such as notebook personal computers and mobile phones are required to be lighter and more compact. Therefore, a printed circuit board on which a CPU, an LSI, or the like inside an electronic device is mounted is naturally required to be small and lightweight. In order to realize the reduction in size and weight, it is necessary to reduce the thickness of the insulating resin layer, the width of the printed wiring and the distance between the wirings, and to reduce the diameter of the through hole and thin the through hole. Here, if the plating thickness is reduced, cracks may occur in the plated metal during thermal shock, and the insulating resin is required to have heat resistance and crack resistance. At the same time, there is a demand for higher speed of these information processing devices, and the clock frequency of CPUs is increasing. Therefore, it is required to increase the signal propagation speed, and in order to realize this, a printed circuit board having a low dielectric constant and a low dielectric loss tangent is required.

A cyanate resin is used as a resin having excellent heat resistance and excellent dielectric properties (for example, JP-A-8-8).
No. 501). The cyanate resin does not produce a functional group having a large polarizability such as a hydroxyl group due to the curing reaction, and therefore has excellent dielectric properties.

However, the cyanate resin has a drawback that it has a high water absorption rate due to its skeletal structure. Therefore, under high-temperature and high-humidity conditions, water absorption of the cyanate resin causes deterioration of dielectric properties, particularly in a high-frequency region above gigahertz. Further, the cyanate resin also has poor flame retardancy, which is also a problem.

[0005]

An object of the present invention is to provide a resin composition, a metal foil with a resin and a printed wiring board which are excellent in dielectric properties, heat resistance and flame retardancy.

[0006]

These objects can be achieved by the present invention described in (1) to (7) below. (1) A resin composition constituting an insulating layer of a resin-coated metal foil, comprising a novolac cyanate resin and a bismaleimide compound. (2) The novolac cyanate resin has the following formula (I)
The resin composition according to (1) above, which is represented by

[Chemical 2] (3) The resin composition according to the above (1) or (2), wherein the content of the novolac cyanate resin is 20 to 80% by weight of the entire resin composition. (4) The resin composition according to any one of (1) to (3) above, wherein the content of the bismaleimide compound is 10 to 40% by weight of the entire resin composition. (5) A resin-coated metal foil obtained by applying the resin composition according to any one of (1) to (4) to a metal foil. (6) A resin-coated metal foil comprising at least two resin layers made of the resin composition according to any one of (1) to (4). (7) A multilayer printed circuit board comprising the resin-coated metal foil according to (5) or (6) above, which is superposed on one side or both sides of the inner layer circuit board and heated and pressed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The resin composition, metal foil with resin and multilayer printed circuit board of the present invention will be described in detail below. The resin composition of the present invention is a resin composition that constitutes an insulating layer of a resin-coated metal foil, and is characterized by containing a novolac cyanate resin and a bismaleimide compound. The resin-coated metal foil of the present invention is characterized in that the resin composition is applied to the metal foil. Further, the multilayer printed circuit board of the present invention,
The resin-coated metal foil is laminated on one side or both sides of the inner layer circuit board and heated and pressed.

First, the resin composition will be described. The resin composition of the present invention constitutes the insulating layer of the resin-coated metal foil. The insulating layer of the resin-coated metal foil is required to have dielectric properties, heat resistance, flame retardancy, and the like. The resin composition of the present invention contains a novolac cyanate resin. This can improve the dielectric properties and flame retardancy of the insulating layer. The novolac cyanate resin is not particularly limited as long as it is a resin containing a novolac cyanate group. Among these, it is preferable to include the novolac cyanate resin represented by the general formula (I). As a result, the glass transition temperature can be increased, and the resin characteristics and flame retardancy after curing can be further improved.

[Chemical 3] The n of the novolac type cyanate resin represented by the formula (I) is not particularly limited, but is preferably 1 to 10 and particularly preferably 1 to 7. If the amount is less than this, the novolac type cyanate resin is likely to be crystallized, and the solubility in a general-purpose solvent is relatively lowered, so that handling may be difficult. On the other hand, if it is more than the above range, the crosslink density becomes too high, which may cause a phenomenon such as deterioration of water resistance and brittleness of a cured product. The novolac cyanate resin has very excellent dielectric properties because a functional group having a large polarizability such as a hydroxyl group is not generated by the curing reaction. Moreover, it has excellent heat resistance because it has a rigid chemical structure.

The content of the novolac cyanate resin is not particularly limited, but is 20-80% of the total resin composition.
Weight% is preferable, and 45 to 70 weight% is particularly preferable.
When the content is less than the lower limit value, the relative dielectric constant, the effect of improving dielectric properties such as dielectric loss tangent may be insufficient, and when the content exceeds the upper limit, the water absorption rate increases and the dielectric property in the high frequency region deteriorates. There is.

The resin composition of the present invention contains a bismaleimide compound. Thereby, toughness can be imparted. By using the above-mentioned novolac cyanate resin and the bismaleimide compound in combination, it is possible to improve flame retardancy and heat resistance without deteriorating water absorption and dielectric properties in a high frequency region. The novolac type cyanate resin produces a triazine ring by the curing reaction, but the triazine ring has excellent symmetry and thus has small polarization and excellent dielectric properties. Moreover, since the crosslink density is high, the glass transition temperature is high and the heat resistance is excellent. However, the novolac type cyanate resin has a drawback that strain is generated at the time of curing due to its high crosslink density and unreacted cyanate groups remain, resulting in poor dielectric properties at high frequencies. In the present invention, in order to solve this problem, a novolac type cyanate resin is used in combination with a bismaleimide compound. The bismaleimide compound has excellent dielectric properties at high frequencies. Further, the double bond of maleimide reacts with the cyanate group, so that it can be incorporated into the resin skeleton, and the unreacted cyanate group can be completely reacted. Further, since the bismaleimide compound has excellent heat resistance, it does not lower the heat resistance of the novolac type cyanate resin. Examples of the bismaleimide compound include N, N '-(4,4'-diphenylmethane) bismaleimide and bis (3-ethyl-5).
-Methyl-4maleimidophenyl) methane, 2,2'-
Examples thereof include bis [4- (4-maleimidophenoxy) phenyl] propane. Among these, 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane is preferable. This makes it possible to improve metal adhesion and reduce water absorption.

The content of the bismaleimide compound is not particularly limited, but is 10 to 40% by weight of the total resin composition.
Is preferable, and 15 to 35% by weight is particularly preferable. If the content is less than the lower limit, the effect of improving the adhesion to metal may be reduced, and if the content exceeds the upper limit, the cured resin product may become brittle.

The resin composition of the present invention contains the above-mentioned novolac cyanate resin and a bismaleimide compound, but other resins, flame retardants, curing accelerators, coupling agents, There is no problem in adding a UV absorber and other components.

Next, the resin-coated metal foil will be described.
The resin-coated metal foil of the present invention is a resin-coated metal foil obtained by applying the resin composition to a metal foil. When the resin composition is applied to the metal foil, it may be applied in one layer, but it is preferable to apply it in two or more layers. When two or more layers are applied, the first layer preferably contains 12 to 200 parts by weight of the bismaleimide compound and 0.5 to 2 parts by weight of the curing catalyst with respect to 100 parts by weight of the novolac cyanate resin. For the second layer, it is preferable to add 12 to 200 parts by weight of the bismaleimide compound and 0.05 to 0.3 parts by weight of the curing catalyst to 100 parts by weight of the novolac cyanate resin. Thereby, the variation in the thickness of the insulating resin layer can be controlled.

When the above-mentioned resin composition is applied to the metal foil, it is usually performed in the form of varnish. Thereby, the coatability can be improved. The solvent used for preparing the varnish preferably has good solubility in the resin composition, but a poor solvent may be used as long as it does not adversely affect the resin composition. Good solvents include DMF, MEK,
Examples thereof include cyclohexanone.

When the varnish is prepared, the solid content of the resin composition is not particularly limited, but is preferably 20 to 90% by weight, and particularly preferably 30 to 70% by weight. Examples of the metal forming the metal foil include copper or a copper-based alloy, aluminum or an aluminum-based alloy, and the like.

A resin-coated metal foil can be obtained by applying the above-mentioned varnish to a metal foil and drying at 80 ° C. or higher and 200 ° C. or lower. Resin thickness after coating and drying is 10 to 1
00 μm is preferable, and particularly 20 to 80 μm is preferable in that the resin layer does not crack and the powder is less likely to drop during cutting.

Next, the multilayer printed wiring board will be described. The multilayer printed circuit board of the present invention is a multilayer printed circuit board obtained by superposing the above-mentioned metal foil with resin on one side or both sides of the inner layer circuit board and heating and pressing. The above-mentioned metal foil with resin is laminated on one side or both sides of the inner layer circuit board and heated and pressed to obtain a laminated board. The heating temperature is not particularly limited, but 140 to 240 ° C. is preferable. The pressure to be applied is not particularly limited, but is preferably 10 to 40 kg / cm ² . Further, the inner layer circuit board may be, for example, one in which circuits are formed on both surfaces of a copper clad laminate and blackened.

[0018]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto. (Example 1) Preparation of varnish 70 parts by weight of PT-60 (manufactured by Lonza Japan) as a novolac cyanate resin, and 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane 30 as a maleimide compound. A varnish was obtained by adding a part by weight to cyclohexanone and adjusting the concentration of the nonvolatile components to 55% by weight.

Coating on Copper Foil Using a varnish prepared by dissolving 1 part by weight of tris (acetylacetonato) cobalt (III) as a curing catalyst in the above resin varnish, copper foil (thickness 0.018 mm, Furukawa Resin foil varnish with a thickness of 0.0
It is coated with 7 mm and dried in a dryer oven at 120 ° C for 10 minutes, 150
The resin layer was dried as a first layer for 10 minutes in a dryer oven at ℃. Next, using a varnish prepared by dissolving 0.1 part by weight of tris (acetylacetonato) cobalt (III) as a curing catalyst in the resin varnish described above, a resin varnish having a thickness of 0.07 mm was formed on the first layer. And was dried in a dryer oven at 120 ° C. for 10 minutes and in a dryer oven at 150 ° C. for 10 minutes to produce a resin-coated copper foil having a resin thickness of 0.07 mm.

Production of Multilayer Printed Wiring Board A copper foil surface of a double-sided copper clad laminate is subjected to blackening treatment (formation of copper oxide), and the reduced product is used as a core. Min., 90 minutes at 200.degree. C., and heat and pressure adhesion was performed to manufacture a multilayer printed wiring board.

Example 2 The procedure of Example 1 was repeated except that the novolac cyanate resin was 65 parts by weight and the 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane was 35 parts by weight. .

Example 3 The procedure of Example 1 was repeated except that 90 parts by weight of novolac cyanate resin and 10 parts by weight of 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane were used. .

Example 4 40 parts by weight of novolac cyanate resin and 40 parts by weight of 2,2'-bis [4- (4-maleimidophenoxy) phenyl] propane were used, and brominated bisphenol A epoxy resin (bromination rate) was used. 50%,
Example 1 was repeated except that 20 parts by weight of epoxy equivalent 400) was added.

Example 5 As a maleimide compound,
Same as Example 1 except 2,2′-bis [4- (4-maleimidophenoxy) phenyl] propane was used.

Example 6 The procedure of Example 1 was repeated, except that the coating of the copper foil of the varnish was carried out once as follows. Using a varnish prepared by dissolving 0.1 part by weight of tris (acetylacetonato) cobalt (III) as a curing catalyst in the resin varnish described above, a copper foil (thickness 0.018 mm, manufactured by Furukawa Circuit Foil Co., Ltd.) is used. Resin varnish with a thickness of 0.
Apply 140mm for 10 minutes in a 150 ° C dryer oven.
Dry in a dryer oven at 70 ℃ for 10 minutes to obtain a resin thickness of 0.07
A 0 mm resin-coated metal foil was prepared.

Comparative Example 1 The procedure of Example 1 was repeated except that the maleimide compound was not used and 100 parts by weight of the novolac cyanate resin was used.

(Comparative Example 2) Instead of the maleimide compound, a polybutadiene resin (manufactured by JSR, molecular weight 100,
000) was used, and the same procedure as in Example 1 was performed.

The following evaluations were performed on the multilayer printed circuit boards obtained in the examples and comparative examples. The method of each evaluation is also shown. The results obtained are shown in Table 1. Dielectric Properties Dielectric properties were measured in the A state by a void measurement method for 1 MHz and a triplate resonator method for 1 GHz.

Formability The formability was evaluated by the presence or absence of voids after the multilayer printed wiring board was prepared. The presence or absence of voids was visually determined. Each symbol represents the following items. A: No void is generated. ◯: Some voids are generated, but there is no practical problem. Δ: Some voids are generated and cannot be practically used.

Copper foil peel strength Copper foil peel strength was measured according to JIS C 6481.

Solder heat resistance Solder heat resistance is measured according to JIS C 6481,
After boiling and absorbing moisture for 2 hours, put it in a solder bath at 260 ℃.
It was examined whether or not there was an abnormality in appearance after soaking for 20 seconds. Each symbol indicates the following items. ⊚: Good without swelling or delamination. X: There is both swelling and delamination, which is not practical.

Flame retardance The flame retardancy was measured according to UL94.

[0033]

[Table 1]

As is clear from Table 1, Examples 1 to 6 are
It had excellent dielectric properties, heat resistance and flame retardancy. Moreover, especially Examples 1-5 were excellent in moldability. Moreover, especially Examples 1 and 2 were excellent in the copper foil peel strength.

[0035]

According to the present invention, it is possible to obtain a resin composition excellent in dielectric properties, heat resistance and flame retardancy, a metal foil with a resin and a multilayer printed wiring board. Further, when a specific maleimide compound is used, the metal adhesion of the resin composition or the like can be particularly improved. Further, when the insulating layer of the metal foil with resin is formed of two layers, particularly excellent moldability can be obtained.

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Claims (7)

[Claims] 1. A resin composition constituting an insulating layer of a resin-coated metal foil, comprising: (A) a novolac cyanate resin and (B) a bismaleimide compound. 2. The resin composition according to claim 1, wherein the novolac cyanate resin is represented by the following formula (I). [Chemical 1] 3. The content of the novolac cyanate resin is 20 to 80% by weight of the total resin composition.
Or the resin composition according to 2. 4. The content of the bismaleimide compound is
The resin composition according to any one of claims 1 to 3, which is 10 to 40% by weight of the entire resin composition. 5. A resin-coated metal foil obtained by applying the resin composition according to claim 1 to a metal foil. 6. A resin-coated metal foil comprising at least two resin layers comprising the resin composition according to any one of claims 1 to 4. 7. A multilayer printed circuit board, comprising the resin-coated metal foil according to claim 5 or 6 superposed on one side or both sides of an inner layer circuit board and heated and pressed.