JP2001156409A - Insulation resin composition for printed-wiring board and insulation material with copper clad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation resin composition for printed-wiring boards with improved heat resistance and reliability by a non-halogen-family fire- resistance resin. SOLUTION: The insulation resin composition for printed-wiring boards contains an epoxy resin that does not contain any halogen elements, an epoxy resin curing agent, an electrical insulation whisker, and metal hydroxide as essential constituents. In the insulation material with copper clad, the insulation resin composition for printed-wiring boards is laminated onto the copper foil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition for a printed wiring board which can meet the demand for a thinner and higher density printed wiring board on which electronic components are mounted, and a copper foil using the same. With insulating material.

[0002]

2. Description of the Related Art Conventionally, an epoxy resin composition comprising an epoxy resin, an epoxy resin curing agent, and a curing accelerator has been used as a resin composition for a printed wiring board. Further, since it is necessary to impart flame retardancy to the printed wiring board, a compound having a halogen element such as bromine is generally added as a flame retardant. Specifically, decapromodiphenyl ether, tetrabromobisphenol A, brominated bisphenol A type epoxy resin and the like are used as these flame retardants.

[0003] A multilayer printed wiring board is a wiring board having an electric circuit also in an inner layer. This multilayer printed wiring board is formed on the outer layer surface of a copper-clad laminate containing an inner printed wiring board in which a circuit formed in advance and a copper foil as an outer wiring material are integrated by hot pressing through a prepreg. Obtained by forming a circuit. The prepreg is conventionally bonded to a crow cloth prepreg in which a glass cloth is impregnated with epoxy resin and dried to make the resin a semi-cured state, or a prepreg that does not use a glass cloth and has a film-forming resin in a semi-cured state. Film (see JP-A-6-200216 and JP-A-6-242465) and an adhesive film with a copper foil formed on one side of a copper foil with the adhesive film (see JP-A-6-1968602)
Is used. The film-forming ability referred to here means that troubles such as cracking or chipping of the resin hardly occur during the steps of transporting, cutting, and laminating the prepreg, and the interlayer insulating layer is formed in the portion where the inner layer circuit exists at the time of subsequent hot pressing. It means performance that is unlikely to cause troubles such as abnormal thinning, reduction in interlayer insulation resistance and short circuit.

[0004]

In recent years, the use of non-halogen flame-retardant resins has been required due to environmental problems. In recent years, electronic devices have been reduced in size, performance, and cost, and printed wiring boards have been required to have higher density, thinner, higher reliability, and lower cost. Multilayering is being performed to increase the density of printed wiring boards, and thinning is being dealt with by reducing the thickness of the inner substrate and prepreg, but when the prepreg using glass cloth is made thinner, The reliability such as heat resistance and electric corrosion resistance is reduced.

On the other hand, an adhesive film without a glass cloth or an adhesive film with a shield can be made thinner, and is excellent in small-diameter drill workability, laser hole workability, and surface smoothness.
However, the multilayer printed wiring board made of these prepregs has extremely low rigidity because the outer insulating layer has no glass cloth base material. The lowness of the okabai is extremely remarkable at a high temperature, the deflection is likely to occur in the component mounting process, and the wire bonding property is extremely poor.

In addition, since the outer insulating layer has no glass cloth substrate and has a large thermal expansion coefficient, the difference in thermal expansion from the mounted component is large, the connection reliability with the mounted component is low, and the thermal expansion and contraction of the heating / cooling outlet is reduced. Have many problems such as cracks and breakage easily occurring in the solder connection part due to the above. Therefore, it is not possible to meet the increasing demand for thinner and higher density multilayer printed wiring boards using the current adhesive film without glass cloth or adhesive film with copper foil.

Accordingly, the present invention provides an insulating resin composition for a printed wiring board which uses a non-halogen flame-retardant resin and is excellent in heat resistance and reliability, and an insulating material with a copper foil using the same. is there.

[0008]

The present invention relates to the following. (1) An insulating resin composition for a printed wiring board which contains, as essential components, an epoxy resin containing no halogen element, an epoxy resin curing agent, an electrically insulating whisker and a metal hydroxide. (2) The total amount of the nitrogen element contained in these compounds is 1.0% by weight based on the total amount of the epoxy resin, the epoxy resin curing agent and the curing accelerator used as required.
The insulating resin composition for a printed wiring board according to the above item (1). (3) The insulating resin composition for a printed wiring board according to (1) or (2), wherein the total of the electrically insulating whiskers and the metal hydroxide is 30% by volume or more. (4) The electrically insulating whisker is characterized in that the whisker is aluminum or magnesium shelflate.
The woven resin composition for a printed wiring board according to any one of (3). (5) The item (1) to wherein the metal hydroxide is aluminum hydroxide or magnesium hydroxide.
The insulating resin composition for a printed wiring board according to any one of (4). (6) The insulating resin composition for a printed wiring board according to any one of (1) to (5), wherein the epoxy resin curing agent is a dicyandiamide or melamine-modified phenol novolak resin. (7) A copper foil characterized in that the insulating resin composition for a printed wiring board according to any one of (1) to (6) is provided on a roughened surface of the copper foil having at least one roughened surface. With insulation.

Hereinafter, the present invention will be described in detail. The epoxy resin used in the present invention may be any compound as long as it has two or more epoxy groups in the molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin ,
There are aliphatic chain epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy paste, epoxidized polybutadiene, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, etc., especially bisphenol A type epoxy resin and cresol novolak type epoxy resin. A mixture with a polyfunctional epoxy resin such as a resin is preferable for improving the inner layer circuit filling property and heat resistance.
These compounds may have any molecular weight,
More than one type can be used in combination.

The epoxy resin curing agent used in the present invention may be any one as long as it is generally used as a curing agent for epoxy resins, and examples thereof include amines, phenols and imidazoles. Among these, amines such as dicyandiamide, phenols such as melamine-modified phenol novolak resins have a high nitrogen element content,
It is preferable for improving the flame retardancy. Some of these compounds can be used in combination.

The ratio of the epoxy resin curing agent to the epoxy resin is 2 to 100 parts by weight of the epoxy resin.
When the amount of the epoxy resin curing agent is less than 2 parts by weight, the curing of the epoxy resin tends to be insufficient and the heat resistance tends to decrease. When the amount is more than 100 parts by weight, the curing agent is It becomes excessive and functions as a plasticizer, and the heat resistance also tends to decrease.

The resin composition for a printed wiring board according to the present invention preferably contains a curing accelerator. The curing accelerator may be any as long as it promotes a usual curing reaction of an epoxy resin, and examples thereof include imidazoles, organic phosphorus compounds, tertiary amines, and quaternary ammonium salts. The ratio of the curing accelerator to the epoxy resin is 0.01 to 100 parts by weight of the epoxy resin.
A range of 10 parts by weight is preferred. When the amount of the curing accelerator is less than 0.01 part by weight, the curing of the epoxy resin tends to be insufficient and the heat resistance tends to decrease. When the amount is more than 10 parts by weight, the curing accelerator becomes excessive and the heat resistance is reduced. Tends to decrease. Many compounds having a nitrogen element correspond to the curing accelerator, and are effective in making the composition difficult.

[0013] The total amount of nitrogen element contained in the epoxy resin, the epoxy resin curing agent, and the curing accelerator used as required may be 1.0% by weight or more based on the total amount. It is preferable to make the resin composition for printed wiring boards in the present invention flame-retardant.

The electrically insulating whiskers used in the present invention preferably have an elastic modulus of 200 GPa or more.
When the elastic modulus is less than 200 GPa, there is a tendency that sufficient rigidity cannot be obtained when a multilayer printed wiring board is formed. As such an electrically insulating whisker, an electrically insulating ceramic whisker is preferable.

The whiskers include, for example, aluminum borate, magnesium borate, wollastonite,
One or more selected from potassium titanate, basic magnesium sulfate, silicon nitride, and α-alumina can be used. Among them, aluminum borate whiskers and magnesium borate whiskers are preferable because they have a flame retardant effect. If the average diameter of the whiskers exceeds 3 μm, the flatness of the surface is adversely affected, and the microscopic uniform dispersion of the whiskers may be impaired.
The average diameter is preferably 3 μm or less. Furthermore, the average diameter is most preferably 1 μm or less for the same reason and good coatability (easy to apply smoothly).

The average length of the whiskers is preferably at least 10 times the average diameter, and if it is less than 10 times, the reinforcing effect as a fiber tends to decrease. There is a tendency that two-dimensional orientation in the layer tends to be difficult, and when formed into a wiring board, the rigidity may be insufficient. For this reason, it is further preferred that the average length of the whiskers is at least about 20 times the average diameter. However, if the whiskers are too long, uniform dispersion in the varnish becomes difficult and the coating properties tend to decrease, and the probability that a whisker in contact with one conductor circuit contacts another conductor circuit Therefore, the average length of the whiskers is preferably 100 μm or less, and more preferably 50 μm or less, because of the risk of causing a short circuit between circuits due to migration of copper ions that tend to move along the fiber.

The metal hydroxide used in the present invention is, for example,
Aluminum hydroxide, magnesium hydroxide, calcium hydroxide and the like. Among them, aluminum hydroxide and magnesium hydroxide are preferable because of their high flame retardant effect.
In order to further increase the rigidity and heat resistance of the printed wiring board, it is also effective to use whiskers and metal hydroxides surface-treated with a coupling agent.

Whiskers surface-treated with a coupling agent are excellent in wettability and bonding with a resin, and can improve rigidity and heat resistance. As the coupling agent used at this time, known compounds such as silicon-based, titanium-based, aluminum-based, zirconium-based, zirconaluminum-based, chromium-based, boron-based, phosphorus-based, and amino acid-based can be used.

The proportions of the electrically insulating whiskers and the metal hydroxide in the insulating resin composition for a printed wiring board may be in any range. The content is preferably 5 to 45% by volume, and the total is preferably 30 to 50% by volume. If at least one of the electrically insulating whisker and the metal hydroxide is less than 5% by volume or less than 30% by volume in total, the flame retardancy is reduced, and the flame may be burned in a combustion test according to the 94UL standard. On the other hand, if it exceeds 50% by volume in total, it is not preferable because the adhesiveness of the multilayer printed board to the inner layer board and the resin filling property between the inner layer circuits are reduced.

For mixing the insulating resin for a printed wiring board of the present invention, it is preferable to add a solvent. The solvent may be any one that dissolves the composition comprising the epoxy resin, the epoxy resin curing agent and the curing accelerator used as necessary, and particularly acetone, methyl ethyl ketone, methyl butyl ketone, and toluene. , Xylene,
Ethyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, ethanol, ethylene glycol monomethyl ether, etc. are excellent in solubility of the above composition,
It is preferable because it has a relatively low boiling point. The amount of these solvents may be any amount as long as the composition can be dissolved and the electrically insulating whiskers and metal hydroxide can be mixed, but the amount is 5 to 300 parts by weight based on 100 parts by weight of the composition. Is more preferable, and the range of 30 to 200 parts by weight is more preferable. These may be used in combination of two or more.

In order to uniformly disperse the electrically insulating whiskers and metal hydroxide, it is effective to use a grinder, a homogenizer or the like.

The insulating resin composition for a printed wiring board according to the present invention can be laminated on a copper foil to form an insulating material with a copper foil. This insulating material with a copper foil can be produced by applying the above-mentioned insulating resin composition for a printed wiring board to a copper foil. The copper foil preferably has one surface roughened. It is preferable that the insulating resin composition for a printed wiring board is laminated on one side of the roughened surface.

As the copper foil, there can be used an electrolytic copper foil, a rolled copper foil, and an ultra-thin copper foil with a carrier film, which are conventionally used for printed wiring boards having at least one roughened surface. The thickness of the copper foil is preferably small, and is preferably 30 μm or less, because a fine circuit can be formed. More preferably, an ultra-thin copper foil of 10 μm is preferable, but in this case, it is preferable to use a copper foil with a carrier film because it is difficult to handle it alone.

When the above insulating resin composition is laminated on a smooth copper foil surface and the insulating resin composition is B-staged or processed into a printed wiring board (including a multilayer printed wiring board), Adhesion between the resin and the insulating resin composition cannot be sufficiently ensured. Therefore, in the present invention, it is preferable to form the above-mentioned insulating resin composition on the roughened surface of the copper foil. The thickness of the insulating resin composition is preferably from 20 to 150 μm.

When the above-mentioned insulating resin composition varnish is applied to a copper foil, a shear force is applied in a plane parallel to the copper foil such as a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a transfer roll coater. Or a coating method capable of applying a compressive force in a direction perpendicular to the surface of the copper foil.

The insulating resin composition of the present invention is impregnated into a substrate such as a paper substrate or a fiber substrate
-It may be staged to form a prepreg, and after impregnating a base material such as a paper base material or a fiber base material such as glass fiber, a copper foil is laminated on one or both surfaces of the prepreg to form a prepreg.
-It may be staged and may be a prepreg with copper foil, or may be laminated on the surface of copper foil to form an adhesive with copper foil. The adhesive with copper foil may be laminated on the inner layer board on the adhesive side to form a laminate for a multilayer wiring board. This is processed into a multilayer printed wiring board.

[0027]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 100 parts by weight of bisphenol A novolak type epoxy resin (epoxy equivalent: 205), 10 parts by weight of dicyandiamide, 1 part by weight of N-methylimidazole, aluminum borate whisker (average diameter 0.9 μm, average length 30 μm)
m) 60 parts by weight, 50 parts by weight of aluminum hydroxide and 100 parts by weight of methyl ethyl ketone were weighed and stirred to obtain a varnish.

In the resin composition obtained by removing methyl ethyl ketone from the varnish, aluminum borate whiskers contained 1
5% by volume and aluminum hydroxide occupy 16% by volume, and the total ratio of the nitrogen element in the total resin of the epoxy resin, the epoxy resin curing agent and the curing accelerator is 6.3% by weight.

This varnish was dried on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater to a thickness of 50 μm.
It was applied to a thickness of μm and dried at 140 ° C. for 3 minutes to obtain a semi-cured insulating material with copper foil.

The obtained insulating material with a copper foil was laminated on the insulating resin side, and heated and pressed at 170 ° C., 2 MPa, for 1 hour using a press to obtain a double-sided copper-clad insulating resin cured product.

The obtained double-sided copper-laminated insulating resin cured product 2
The solder heat resistance at 88 ° C. is good without swelling or the like for 300 seconds or more, and the cured insulating resin from which copper has been removed by etching has a maximum burning time of 5 seconds in a combustion test and an average burning time of 3 seconds. It showed flammability.

Furthermore, an inner layer circuit board produced by removing unnecessary portions of copper foil on both sides of a double-sided copper-clad laminate having an insulating layer thickness of 0.1 mm and a copper foil for conductor of 18 μm by etching. The insulating material with the copper foil obtained on both sides of the resin was placed on the insulating layer with the insulating resin side facing the inner layer circuit, and pressed using a press.
Heating and pressing were performed at 0 ° C. and 2 MPa for 1 hour to obtain a multilayer copper-clad laminate having an inner circuit. As a result of removing the copper foil of this laminated plate by etching and visually observing, there was no defect such as void or blur.

Example 2 100 parts by weight of bisphenol A novolak type epoxy resin (epoxy equivalent 205), 60 parts by weight of melamine-modified phenol novolak resin (phenolic hydroxyl equivalent 120, nitrogen atom content 8% by weight), N-methylimidazole 1 50 parts by weight, magnesium borate whisker (average diameter 1.0 μm, average length 30 μm), magnesium hydroxide 100 parts by weight, methyl ethyl ketone 200
A part by weight was weighed and stirred to obtain a varnish. In the resin composition obtained by removing methyl ethyl ketone from the varnish, magnesium borate whiskers accounted for 13% by volume, magnesium hydroxide accounted for 22% by volume, and the total nitrogen content of the epoxy resin, epoxy resin curing agent and curing accelerator in the total resin The ratio of the elements was 5.1% by weight.

The varnish was dried on a roughened surface of an electrolytic copper foil having a thickness of 18 μm with a knife coater to have an insulating resin thickness of 50 μm.
It was applied to a thickness of μm and dried at 140 ° C. for 3 minutes to obtain a semi-cured insulating material with copper foil.

The obtained insulating material with copper foil was overlaid on the insulating resin side, and heated and pressed at 170 ° C., 2 MPa for 1 hour using a press to obtain a double-sided copper-clad insulating resin cured product.

The double-sided copper-laminated insulating resin cured product 2
The solder heat resistance at 88 ° C is good without swelling or the like for 300 seconds or more, and the cured insulating resin obtained by stripping copper has a maximum burning time of 1 second in a burning test and an average burning time of 0.2 seconds. Showed flame retardancy.

Further, an inner circuit board prepared by removing unnecessary portions of copper foil on both sides of a double-sided copper-clad laminate having an insulating layer thickness of 0.1 mm and a copper foil for conductor of 18 μm by etching. The insulating material with the copper foil obtained on both sides of the resin was placed on the insulating layer with the insulating resin side facing the inner layer circuit, and pressed using a press.
Heating and pressing were performed at 0 ° C. and 4 MPa for 1 hour to obtain a multilayer copper-clad laminate having an inner circuit. The lamination of the laminate was removed by etching and visually observed. As a result, no defects such as voids and blurring were found.

COMPARATIVE EXAMPLE 1 Double-sided copper paste was applied in the same manner as in Example 2 except that 40 parts by weight of phenol novolak resin and 120 parts by weight of magnesium borate whisker were added to the curing agent, and no magnesium hydroxide was added. The cured resin burned in the combustion test. In the resin composition obtained by removing methyl ethyl ketone from the varnish, magnesium borate whiskers accounted for 25% by volume, and the total ratio of the nitrogen element in the total resin of the epoxy resin, the epoxy resin curing agent, and the curing accelerator was 0.2%. % By weight.

[0040]

According to the present invention, the insulating resin composition for a printed wiring board of the present invention can be made flame-retardant without using a halogen-based flame retardant. Can be. Moreover, they are excellent in heat resistance and reliability

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08K 3/22 C08K 3/22 3/38 3/38 7/04 7/04 C08L 63/00 C08L 63 / 00Z H05K 3/46 H05K 3/46 T (72) Inventor Tomio Fukuda 1500 Oji Ogawa, Shimodate City, Ibaraki Pref. Hitachi Chemical Industry Co., Ltd. Within the Kasei Kogyo Co., Ltd. (72) Inventor Toshihisa Kumakura 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture Within the Hitachi Kasei Kogyo Co., Ltd. (72) Kiyoshi Hirosawa 1500 Oji Ogawa Shimodate City, Ibaraki Prefecture F term in the company research institute (reference) 4J002 CC27X CD01W CD05W CD06W CD08W CD11W CD13W CD18W DE079 DE089 DE148 DE149 DE188 DG048 DJ008 DK008 EJ006 EN 006 EN007 EN137 ER026 EU116 EU117 EW007 FA038 FB078 FB088 FB098 FB168 FD128 FD139 FD14X FD146 FD157 GQ01 4J036 AA01 AD08 AD21 AF06 AF08 AG00 AH00 AK03 DB05 DC01 DC05 DC31 DC40 DD07 FB08 GA02 CC08 5H

Claims (7)

[Claims] An epoxy resin containing no halogen element,
An insulating resin composition for a printed wiring board, comprising an epoxy resin curing agent, an electrically insulating whisker and a metal hydroxide as essential components. 2. The total amount of the nitrogen element contained in these compounds is 1 to the total amount of the epoxy resin, the epoxy resin curing agent and the curing accelerator used as required.
The insulating resin composition for a printed wiring board according to claim 1, which is 0% by weight or more. 3. The method according to claim 1, wherein the total of the electrically insulating whiskers and the metal hydroxide is 30% by volume or more.
Or the insulating resin composition for a printed wiring board according to 2. 4. The woven resin composition for a printed wiring board according to claim 1, wherein the electrically insulating whiskers are aluminum or magnesium shelflate. 5. The method according to claim 1, wherein the metal hydroxide is aluminum hydroxide or magnesium hydroxide.
5. The insulating resin composition for a printed wiring board according to any one of items 1 to 4. 6. The insulating resin composition for a printed wiring board according to claim 1, wherein the epoxy resin curing agent is a dicyandiamide or melamine-modified phenol novolak resin. 7. A copper foil, wherein the insulating resin composition for a printed wiring board according to claim 1 is provided on a roughened surface of a copper foil having at least one surface roughened. Insulating material.