JP2005154512A - Nonhalogen flame-retardant adhesive composition and its use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a nonhalogen flame-retardant adhesive composition having excellent flame retardance, adhesiveness and migration resistance, a copper-clad laminate for a flexible printed wiring board, a flexible printed board and a cover lay film for a flexible printed wiring board using the adhesive composition. <P>SOLUTION: The nonhalogen flame-retardant resin composition comprises a base resin 11 composed of at least an epoxy resin, a curing agent and carboxy group-containing rubber, surface-treated aluminum hydroxide particles 10 in the ratio of the aluminum hydroxide particles to the total of the base resin and the aluminum hydroxide particles of 25-50 mass%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a non-halogen flame retardant adhesive composition excellent in flame retardancy, adhesion and migration resistance, a copper-clad laminate for flexible printed wiring boards using this non-halogen flame retardant adhesive composition, flexible print The present invention relates to a substrate and a coverlay film for a flexible printed wiring board.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a flexible printed circuit board.
The flexible printed circuit board 1 includes a base film 2, a base film side adhesive layer 3 provided on one surface of the base film 2, a copper foil provided on the base film side adhesive layer 3, and the like. The circuit 4 made of the metal foil, the cover lay film side adhesive layer 5 provided on the circuit 4 and the base film side adhesive layer 3, and the upper surface of the cover lay film side adhesive layer 5 are all covered. And a coverlay film 6 provided in this manner.

Such a flexible printed circuit board is required to have various characteristics. Above all, flame retardancy is an important characteristic as well as electrical characteristics and heat resistance.
Conventionally, in order to make a flexible printed circuit board flame-retardant, a method of mixing a flame retardant with each constituent material has been used.

In the flexible printed circuit board as shown in FIG. 1, in order to make the adhesive for forming the base film side adhesive layer 3 and the coverlay film side adhesive layer 5 flame retardant, a halogen-based base resin or flame retardant is used. A flame retardant adhesive composition using a phosphorus compound is used (for example, see Patent Documents 1 to 10).
JP 9-48092 A Japanese Patent Laid-Open No. 9-51164 JP 2001-339131 A JP 2001-339132 A JP-A-10-112576 JP 2003-27029 A JP 2003-27028 A JP 2001-106869 A JP-A-5-245971 JP 2003-41234 A

However, an adhesive containing a halogen compound has a problem of generating a toxic gas during combustion.
In addition, an adhesive containing a phosphorus compound does not exhibit flame retardancy unless a large amount of the phosphorus compound is added to the adhesive, and dendrites due to the phosphorus compound are generated. There are problems such as ease of migration and degradation of migration characteristics.

  The present invention has been made in view of the above circumstances, and is a non-halogen flame-retardant adhesive composition excellent in flame retardancy, adhesion and migration resistance, and a copper for flexible printed wiring boards using this non-halogen flame-retardant adhesive composition An object is to provide a tension laminate, a flexible printed circuit board, and a coverlay film for a flexible printed wiring board.

In order to achieve the above object, the present invention includes a base resin (i) containing at least an epoxy resin, a curing agent, and a carboxyl group-containing rubber, and surface-treated aluminum hydroxide particles (ii), Non-halogen flame retardant adhesive, characterized in that aluminum oxide particles (ii) are blended in a range of 25 to 50 mass% with respect to the total amount of base resin (i) and aluminum hydroxide particles (ii). A composition is provided.
In the non-halogen flame retardant adhesive composition of the present invention, the aluminum hydroxide particles (ii) preferably have a particle size of 3 μm or less.
Further, the aluminum hydroxide particles (ii) were surface-treated by sequentially laminating a first layer made of stearic acid and a second layer made of an organic silane coupling agent on the outer surface of the aluminum hydroxide particles. Those are preferred.

The present invention also provides a copper-clad laminate for a flexible printed wiring board, comprising an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition.
The present invention also provides a flexible printed board comprising an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition.
The present invention also provides a cover lay film for a flexible printed circuit board comprising an adhesive layer obtained by curing a non-halogen flame retardant adhesive composition.

ADVANTAGE OF THE INVENTION According to this invention, the non-halogen flame-retardant adhesive composition excellent in the flame retardance, adhesiveness, and migration resistance can be provided.
In addition, according to the present invention, it is provided with an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition, is excellent in flame retardancy and migration resistance, and can prevent generation of halogen-containing toxic substances such as dioxin during incineration. The copper clad laminated board for flexible printed wiring boards, a flexible printed circuit board, and the coverlay film for flexible printed wiring boards can be provided.

  The halogen-free flame retardant adhesive composition of the present invention includes at least an epoxy resin, a curing agent, a base resin containing a carboxyl group-containing rubber, and surface-treated aluminum hydroxide particles (ii), The aluminum hydroxide particles (ii) are blended in the range of 25 to 50% by mass with respect to the total amount of the base resin (i) and the aluminum hydroxide particles (ii).

  The epoxy resin blended in the base resin (i) is not particularly limited as long as it has two or more epoxy groups in one molecule and does not contain halogen. For example, bisphenol A type epoxy Examples thereof include resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, biphenyl type epoxy resins, naphthalene ring-containing epoxy resins, and alicyclic epoxy resins.

  In addition, the curing agent blended in the base resin (i) is not particularly limited as long as it acts as a curing agent for the epoxy resin and does not contain a halogen. For example, aliphatic amine-based, alicyclic As a curing agent for epoxy resins such as amines, aromatic amines, secondary / tertiary amines, acid anhydrides, dicyandiamide, boron trifluoride complex salts, imidazoles and their derivatives, phenol resins, imidazoles and their derivatives And the like having the action of The compounding amount of this curing agent is 0.8 to 1.2 times the amount of addition, preferably 0.9 to the theoretical addition amount (addition amount with respect to 100 parts by mass of the epoxy resin) calculated from the epoxy equivalent of the epoxy resin. The range is -1.1 times. When the blending amount of the curing agent is less than the above range (less than 0.9 times the theoretical addition amount), the curing agent is insufficient, so that the curing is not sufficient and the electrical characteristics and adhesive strength are reduced. On the other hand, when the addition amount of the curing agent for the epoxy resin exceeds the above range, unreacted curing agent remains and this also causes a decrease in electrical characteristics.

  Further, as the carboxyl group-containing rubber blended in the base resin (i), a synthetic rubber containing a carboxyl group capable of reacting with the epoxy group of the epoxy resin and containing no halogen is used. For example, a carboxyl group-containing nitrile An example is rubber (NBR). Specifically, Nipol 1072 manufactured by Nippon Zeon Co., Ltd., DN601, 601 and FN3703, PNR-1H manufactured by Nippon Synthetic Rubber Co., Hiker CTBN, CTBNX, 1072 manufactured by Goodrich Co., Ltd. and the like can be mentioned. The amount of the carboxyl group-containing rubber is 15 to 50% by mass, preferably 20 to 40% by mass, based on the total amount of essential components of the base resin (i) (epoxy resin + curing agent + carboxyl group-containing rubber). Scope. If the blending amount of the carboxyl group-containing rubber is less than the above range, the flexibility is lowered and hardened. If the blending amount of the epoxy resin exceeds the above range, the amount of seepage during pressing is large and the adhesive strength is lowered. It is not preferable.

  In addition to the epoxy resin, the curing agent, and the carboxyl group-containing rubber, which are essential components, the base resin (i) includes various resins (ester compounds) and various additives as long as the effects of the present invention are not impaired. Can also be suitably blended. Examples of the additive include a filler, a reinforcing material, a coupling agent, a plasticizer, a reactive diluent, an organic solvent, a stabilizer, and the like, and those that do not contain a halogen are selected and used.

  As the surface-treated aluminum hydroxide particles (ii) blended as a flame retardant in the base resin (i), the non-halogen flame retardant adhesive composition is cured on the aluminum hydroxide particles (ii). What gave surface treatment which can raise the bond strength of base resin (i) and aluminum hydroxide particles (ii), improve the adhesive strength of an adhesive agent, and insulation, and can reduce the generation degree of dendrite. A structure in which a first layer made of stearic acid and a second layer made of an organic silane coupling agent are sequentially laminated on the surface of the aluminum hydroxide particles is used.

Examples of the organic silane coupling agent include vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane.
The thickness of the surface treatment layer comprising the first layer and the second layer used for this surface treatment is preferably about 5 to 30% with respect to the particle size of the aluminum hydroxide used.

  The surface-treated aluminum hydroxide particles (ii) preferably have a particle size of 3 μm or less, and more preferably have a particle size of 0.8 μm to 1.5 μm. If this particle size exceeds 3 μm, unevenness will occur in the adhesive layer, and the fluidity of the adhesive will deteriorate when bonded to the copper circuit, and will not be sufficiently embedded in the copper circuit. Problems such as a decrease in peel strength with the layer occur.

  The surface-treated aluminum hydroxide particles (ii) are blended in the range of 25 to 50% by mass with respect to the total amount of the base resin (i) and the aluminum hydroxide particles (ii). When the blending amount of the particles (ii) is less than the above range, the flame resistance of the obtained non-halogen flame retardant adhesive composition is lowered, and conforms to VTM-0 when the UL 94 VTM test for flame retardancy is performed. There is a possibility not to. On the other hand, when the blending amount of the particles (ii) exceeds the above range, the content of the base resin (ii) is decreased, and the adhesive strength of the obtained non-halogen flame retardant adhesive composition may be lowered.

When the halogen-free flame retardant adhesive composition of the present invention is applied to an object, an organic solvent is added to the adhesive composition to form an adhesive solution, and the adhesive solution is applied to the object, dried and cured. Used.
Examples of the organic solvent include methanol, ethanol, acetone, methyl ethyl ketone, toluene, trichloroethylene, and the like. The solid content concentration of the adhesive solution is preferably in the range of 10 to 50% by mass, more preferably in the range of 20 to 40% by mass. If the solid content concentration of the adhesive solution is less than 10% by mass, uneven coating (variation in the thickness of the adhesive layer) tends to occur. On the other hand, when it exceeds 50 mass%, a viscosity will rise and applicability | paintability will deteriorate by the compatibility fall of solid content and an organic solvent.

  The non-halogen flame retardant adhesive composition of the present invention comprises constituent materials (epoxy resin, curing agent, carboxyl group-containing rubber, surface-treated aluminum hydroxide particles, organic solvent, and additives added as necessary). It is prepared by stirring and mixing using a pot mill, a ball mill, a homogenizer, a super mill or the like.

  FIG. 2 is an enlarged view showing an example of a schematic structure of the non-halogen flame retardant adhesive composition of the present invention. In this figure, reference numeral 10 denotes surface-treated aluminum hydroxide particles, and 11 denotes a base resin. The surface-treated aluminum hydroxide particles 10 are present in a dispersed state in the base resin 11 which is a continuous phase. The surface-treated aluminum hydroxide particles 10 were obtained by sequentially laminating a first layer 13 made of stearic acid and a second layer 14 made of an organic silane coupling agent on the surface of the aluminum hydroxide particles 12 (untreated). A surface treatment layer is formed.

  The non-halogen flame retardant adhesive composition of the present invention applies an adhesive solution obtained by adding an organic solvent to an object, and dries and cures, thereby bonding the objects and sealing the objects. Used for. The adhesive composition can be dried and cured at a temperature of about room temperature to about 200 ° C.

Since the non-halogen flame retardant adhesive composition of the present invention does not contain a halogen-containing compound in the material, no harmful gas is generated during incineration, and it is difficult to mix aluminum hydroxide particles excellent in flame retardancy. Excellent in flammability. Further, this non-halogen flame retardant adhesive composition has a high insulation resistance between lines and excellent migration resistance with almost no generation of dendrites. Further, the adhesiveness is not deteriorated and the adhesive strength is stable.
Specifically, the non-halogen flame retardant adhesive composition of the present invention passes VTM-0 of the flame retardant standard UL94VTM test (thin material vertical combustion test) and has an adhesive strength of 7 N / cm or more. Excellent as a flame-retardant adhesive composition, with an insulation resistance of 10 ⁸ Ω or more after being held for 240 hours in an 85 ° C./85% RH atmosphere with a DC voltage of 50 V applied, and substantially free of dendrite. Performance.

The non-halogen flame retardant adhesive composition of the present invention is bonded to the flexible printed circuit board 1 and related devices and parts shown in FIG. 1 (copper-clad laminate for flexible printed wiring boards and coverlay films for flexible printed wiring boards). It is particularly suitable as an agent material.
Therefore, the present invention comprises a copper-clad laminate for a flexible printed wiring board, a flexible printed circuit board, and a cover for a flexible printed wiring board, comprising an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition. Provide lay film.

  The flexible printed circuit board according to the present invention can have the same configuration as the flexible printed circuit board 1 shown in FIG. The flexible printed circuit board 1 includes a base film 2, a base film side adhesive layer 3 provided on one surface of the base film 2, a copper foil provided on the base film side adhesive layer 3, and the like. The circuit 4 made of the metal foil, the cover lay film side adhesive layer 5 provided on the circuit 4 and the base film side adhesive layer 3, and the upper surface of the cover lay film side adhesive layer 5 are all covered. And a coverlay film 6 provided in this manner. And the flexible printed circuit board 1 concerning this invention is comprised by the adhesive bond layer which hardened the said non-halogen flame retardant adhesive composition at least one part, Preferably all of the adhesive bond layers 3 and 5 were comprised.

In the flexible printed circuit board 1, the material of the constituent elements other than the adhesive layers 3 and 5 is not particularly limited.
For example, as the base film 2 and the coverlay film 6, a film having a thickness of 10 μm to 100 μm made of polyimide resin, polyethylene terephthalate resin, or the like is used.
Moreover, as metal foil which comprises the circuit 4, the thing of about 5-100 micrometers in thickness, such as an electrolytic copper foil, a rolled copper foil, and nickel foil, is used.
Moreover, the thickness of the base film side adhesive bond layer 3 or the coverlay film side adhesive bond layer 5 is about 10-100 micrometers.

  Next, the manufacturing method of this flexible printed circuit board is demonstrated. The method for producing this flexible printed circuit board is not particularly limited, and is performed in the same manner as in the conventional method. For example, first, an adhesive solution containing the uncured non-halogen flame retardant adhesive composition is used. It is applied to either one or both of the base film 2 and the coverlay film 6.

  Next, a predetermined pattern of metal foil is laminated on the base film 2, the base film 2 on which the adhesive layer is formed, and the coverlay film 6 are overlapped, and heated and pressed by hot pressing. At this time, the heating temperature is preferably about 140 to 200 ° C., and the heating time is preferably about 0.5 to 3 hours. Thereby, these are integrated and the flexible printed circuit board as shown in FIG. 1 is obtained.

  In such a flexible printed circuit board, either one or both of the base film side adhesive layer and the coverlay film side adhesive layer are formed of the above-mentioned non-halogen flame retardant adhesive composition. It does not generate harmful gas and is not only excellent in flame retardancy but also does not peel off between the layers constituting the flexible printed circuit board.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

(Example 1)
A flexible printed circuit board 1 having the configuration shown in FIG. 1 was produced.
A polyimide resin film with a thickness of 25 μm was used as the base film 2 and the coverlay film 6. A copper foil having a thickness of 18 μm was used as the metal foil constituting the circuit 4.

  Bisphenol A type epoxy resin 37.8% by mass, acid anhydride (manufactured by Hitachi Chemical Co., Ltd., HN5500 (3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride)) 34.8% by mass, carboxyl group Base resin (hereinafter referred to as “base resin A”) composed of 27.0% by mass of nitrile rubber containing and 0.4% by mass of tertiary amine (manufactured by Japan Epoxy Resin, Epicure 3010 (Trisdimethylaminomethylphenol)) .) 75% by mass and water subjected to surface treatment by sequentially laminating a first layer made of stearic acid and a second layer made of a vinyltrimethoxysilane coupling agent on the surface of aluminum hydroxide particles having a particle diameter of 1.2 μm. 100 parts by mass of solid content of aluminum oxide particles (hereinafter referred to as “aluminum hydroxide A”) 25% by mass Was added 150 parts by mass of methyl ethyl ketone, it was stirred and placed in a ball mill, to prepare an adhesive solution of halogen-free flame-retardant adhesive composition.

  Next, this non-halogen flame retardant adhesive composition adhesive solution was applied to one surface of the base film 2 with a bar coater so that the thickness after drying was 10 μm, and dried in an oven at 150 ° C. for 15 minutes. Thus, the base film side adhesive layer 3 was formed.

  Next, a copper foil was laminated on the base film side adhesive layer 3. A comb-shaped pattern of L / S = 100 μm / 100 μm was formed on the copper foil to form a circuit 4.

  Next, the adhesive solution of the non-halogen flame retardant adhesive composition was applied to one surface of the coverlay film 6 with a bar coater so that the thickness after drying was 30 μm, and the oven was heated at 150 ° C. for 15 minutes. The cover lay film side adhesive layer 5 was formed by drying.

Next, the base film 2 and the coverlay film 6 are heated under conditions of 170 ° C., 40 kgf / cm ² and 40 minutes so that the base film side adhesive layer 3 and the coverlay film side adhesive layer 5 face each other. Lamination and lamination were performed to obtain a flexible printed circuit board, which was used as a test sample.

(Example 2)
Instead of the base resin A, 14.1% by mass of a novolac type epoxy resin, 43.6% by mass of a bisphenol A type epoxy resin, 23.4% by mass of a phenol resin, and 18.7% by mass of a nitrile rubber containing a carboxyl group A flexible printed circuit board was prepared in the same manner as in Example 1 except that a base resin composed of 0.2% by mass of imidazole (hereinafter referred to as “base resin B”) was used. It was.

(Example 3)
Instead of the base resin A, a base resin comprising 64.5% by mass of a bisphenol A type epoxy resin, 22.5% by mass of 4,4′-diaminodiphenyl sulfone, and 13.0% by mass of a carboxyl group-containing nitrile rubber (Hereinafter, referred to as “base resin C”.) A flexible printed circuit board was produced in the same manner as in Example 1 except that it was used as a test sample.

Example 4
A flexible printed circuit board was produced in the same manner as in Example 1 except that the blending amount of the base resin A was 70 mass% and the blending amount of the aluminum hydroxide A was 30 mass%, and this was used as a test sample.

(Example 5)
A flexible printed circuit board was produced in the same manner as in Example 2 except that the blending amount of the base resin B was 70 mass% and the blending amount of the aluminum hydroxide A was 30 mass%, and this was used as a test sample.

(Example 6)
A flexible printed circuit board was produced in the same manner as in Example 3 except that the blending amount of the base resin C was 70 mass% and the blending amount of the aluminum hydroxide A was 30 mass%, and this was used as a test sample.

(Example 7)
A flexible printed circuit board was produced in the same manner as in Example 1 except that the blending amount of the base resin A was 60% by mass and the blending amount of the aluminum hydroxide A was 40% by mass, and this was used as a test sample.

(Example 8)
A flexible printed circuit board was produced in the same manner as in Example 2 except that the blending amount of the base resin B was 60% by mass and the blending amount of the aluminum hydroxide A was 40% by mass, and this was used as a test sample.

Example 9
A flexible printed circuit board was produced in the same manner as in Example 3 except that the blending amount of the base resin C was 60 mass% and the blending amount of the aluminum hydroxide A was 40 mass%, and this was used as a test sample.

(Example 10)
A flexible printed circuit board was produced in the same manner as in Example 1 except that the blending amount of the base resin A was 50 mass% and the blending amount of the aluminum hydroxide A was 50 mass%, and this was used as a test sample.

(Example 11)
A flexible printed circuit board was produced in the same manner as in Example 2 except that the blending amount of the base resin B was 50 mass% and the blending amount of the aluminum hydroxide A was 50 mass%, and this was used as a test sample.

(Example 12)
A flexible printed circuit board was produced in the same manner as in Example 3 except that the blending amount of the base resin C was 50 mass% and the blending amount of the aluminum hydroxide A was 50 mass%, and this was used as a test sample.

(Comparative Example 1)
A flexible printed circuit board was produced in the same manner as in Example 1 except that the blending amount of the base resin A was 80 mass% and the blending amount of the aluminum hydroxide A was 20 mass%, and this was used as a test sample.

(Comparative Example 2)
A flexible printed circuit board was prepared in the same manner as in Example 2 except that the blending amount of the base resin B was 80 mass% and the blending amount of the aluminum hydroxide A was 20 mass%, and this was used as a test sample.

(Comparative Example 3)
A flexible printed circuit board was produced in the same manner as in Example 3 except that the blending amount of the base resin C was 80 mass% and the blending amount of the aluminum hydroxide A was 20 mass%, and this was used as a test sample.

(Comparative Example 4)
A flexible printed circuit board was produced in the same manner as in Example 1 except that the blending amount of the base resin A was 45 mass% and the blending amount of the aluminum hydroxide A was 55 mass%, and this was used as a test sample.

(Comparative Example 5)
A flexible printed circuit board was produced in the same manner as in Example 2 except that the blending amount of the base resin B was 45 mass% and the blending amount of the aluminum hydroxide A was 55 mass%, and this was used as a test sample.

(Comparative Example 6)
A flexible printed circuit board was produced in the same manner as in Example 3 except that the blending amount of the base resin C was 45 mass% and the blending amount of the aluminum hydroxide A was 55 mass%, and this was used as a test sample.

(Comparative Example 7)
Instead of aluminum hydroxide A, aluminum hydroxide having a particle size of 1.2 μm (hereinafter referred to as “aluminum hydroxide B”) that has not been surface-treated with stearic acid and a vinyltrimethoxysilane coupling agent is used. A flexible printed circuit board was produced in the same manner as in Example 1 except that the sample was used as a test sample.

(Comparative Example 8)
A flexible printed circuit board was produced in the same manner as in Example 2 except that aluminum hydroxide B was used instead of aluminum hydroxide A, and this was used as a test sample.

(Comparative Example 9)
A flexible printed circuit board was produced in the same manner as in Example 3 except that aluminum hydroxide B was used instead of aluminum hydroxide A, and this was used as a test sample.

(Comparative Example 10)
A flexible printed circuit board was produced in the same manner as in Example 10 except that aluminum hydroxide B was used instead of aluminum hydroxide A, and this was used as a test sample.

(Comparative Example 11)
A flexible printed circuit board was produced in the same manner as in Example 11 except that aluminum hydroxide B was used instead of aluminum hydroxide A, and this was used as a test sample.

(Comparative Example 12)
A flexible printed circuit board was produced in the same manner as in Example 12 except that aluminum hydroxide B was used instead of aluminum hydroxide A, and this was used as a test sample.

About each sample of Examples 1-12 produced as mentioned above and Comparative Examples 1-12, it evaluated about the flame retardance ⁶⁾ , adhesive strength ⁷⁾ , insulation resistance ^8), and dendrite (dendritic crystal) generation | occurrence | production degree ⁹⁾ . .

・ Flame retardant ⁶⁾
For the evaluation of flame retardancy, a test according to the flame retardancy standard UL94VTM (thin material vertical combustion test) was performed, and those that passed VTM-0 were indicated by ◯, and those that failed were indicated by ×.

・ Adhesive strength ⁷⁾
Adhesive strength is bonded to the base film 2 and pressed under the conditions of 170 ° C., 40 kg / cm ² , 40 minutes so that the thickness after drying of the adhesive composition is 30 μm. The strength test was carried out. This peel strength test was carried out in accordance with JIS C 6481. A sample obtained by the press was cut into a width of 10 mm and peeled from the copper foil at a speed of 50 mm / min in the 90 ° direction, and the peel strength at that time was measured. This was taken as the adhesive strength (unit: N / cm).

・ Insulation resistance ⁸⁾
The insulation resistance was measured by measuring the insulation resistance between lines after holding the test sample in an atmosphere of 85 ° C. and 85% RH for 240 hours while applying a DC voltage of 50V. This insulation evaluation was performed in order to evaluate the generation state of the dendrite generated between the copper circuits and the change in the resistance value between the circuits.

・ Dendrite occurrence ⁹⁾
The degree of dendrite generation is to hold the test sample in an atmosphere of 85 ° C. and 85% RH with a DC voltage of 50 V applied for 240 hours, and then check whether dendrite is generated between the circuits using an optical microscope. Went by. Migration resistance was evaluated by checking the presence or absence of dendrites.

  The results of Examples 1-6 are shown in Table 1, the results of Examples 7-12 are shown in Table 2, the results of Comparative Examples 1-6 are shown in Table 3, and the results of Comparative Examples 7-12 are shown in Table 4, respectively. Tables 1 to 4 are shown separately. In these tables, the numerical values related to the base resins A to C and the aluminum hydroxides A and B represent mass%, respectively.

In Tables 1 to 4, 1) to 5) are as follows.
1) Base resin A: 37.8 mass% of bisphenol A type epoxy resin and acid anhydride (HN5500 (3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride) manufactured by Hitachi Chemical Co., Ltd.) A base resin comprising 8% by mass, 27.0% by mass of a carboxyl group-containing nitrile rubber, and 0.4% by mass of a tertiary amine (manufactured by Japan Epoxy Resin, Epicure 3010 (trisdimethylaminomethylphenol)).
2) Base resin B: 14.1% by mass of novolac type epoxy resin, 43.6% by mass of bisphenol A type epoxy resin, 23.4% by mass of phenol resin, 18.7% by mass of carboxyl group-containing nitrile rubber, A base resin comprising 0.2% by mass of imidazole.
3) Base resin C: Base resin composed of 64.5% by mass of bisphenol A type epoxy resin, 22.5% by mass of 4,4′-diaminodiphenylsulfone, and 13.0% by mass of carboxyl group-containing nitrile rubber.
4) Aluminum hydroxide A: water surface-treated by sequentially laminating a first layer made of stearic acid and a second layer made of vinyltrimethoxysilane coupling agent on the surface of aluminum hydroxide particles having a particle diameter of 1.2 μm. Aluminum oxide particles.
5) Aluminum hydroxide A: Aluminum hydroxide particles having a particle diameter of 1.2 μm which are not surface-treated.
In Tables 1 to 4, 6) to 9) are the above-mentioned flame retardancy ⁶⁾ , adhesive strength ⁷⁾ , insulation resistance ⁸⁾ and dendrite (dendritic crystal) generation degree ⁹⁾ .

From the result shown to Tables 1-4, Examples 1-12 which concern on this invention set it as the composition which mix | blended 25-50 mass% of aluminum hydroxide particles surface-treated to base resin with respect to those total amounts. As a result, the flame retardancy, the adhesive strength, and the migration resistance (interline insulation resistance, dendrite generation degree) were all good. In addition, as a result of incinerating the adhesives of Examples 1 to 12 and analyzing the generated gas, no halogen-containing harmful substances such as dioxin were detected.
On the other hand, from the results of Comparative Examples 1 to 3, it can be seen that when the surface-treated aluminum hydroxide addition amount is less than 25% by mass, the flame retardancy is lowered and VTM-0 is not passed.
From the results of Comparative Examples 4 to 6, it can be seen that when the addition amount of the surface-treated aluminum hydroxide exceeds 50% by mass, the adhesive strength decreases.
From the results of Comparative Examples 7 to 12, it can be seen that when aluminum hydroxide that is not surface-treated is used, dendrites are generated between the circuits, and the insulation resistance is lowered.

It is sectional drawing which shows an example of a flexible printed circuit board. 1 is an enlarged view showing a schematic structure of a non-halogen flame retardant adhesive composition according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flexible printed circuit board, 2 ... Base film, 3 ... Base film side adhesive layer, 4 ... Circuit, 5 ... Coverlay film side adhesive layer, 6 ... Coverlay film, 10 ... Surface-treated aluminum hydroxide particle, DESCRIPTION OF SYMBOLS 11 ... Base resin, 12 ... Aluminum hydroxide particle, 13 ... 1st layer, 14 ... 2nd layer.

Claims (6)

A base resin (i) including at least an epoxy resin, a curing agent, and a carboxyl group-containing rubber, and surface-treated aluminum hydroxide particles (ii);
Non-halogen flame retardant, characterized in that the aluminum hydroxide particles (ii) are blended in the range of 25 to 50% by mass with respect to the total amount of the base resin (i) and the aluminum hydroxide particles (ii). Adhesive composition.   The halogen-free flame retardant adhesive composition according to claim 1, wherein the aluminum hydroxide particles (ii) have a particle size of 3 µm or less.   The aluminum hydroxide particles (ii) are surface-treated by sequentially laminating a first layer made of stearic acid and a second layer made of an organic silane coupling agent on the outer surface of the aluminum hydroxide particles. The non-halogen flame retardant adhesive composition according to claim 1, wherein the non-halogen flame retardant adhesive composition is present.   A copper-clad laminate for a flexible printed wiring board, comprising an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition according to claim 1.   A flexible printed circuit board comprising an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition according to claim 1. A coverlay film for a flexible printed wiring board, comprising an adhesive layer obtained by curing the non-halogen flame retardant adhesive composition according to claim 1.

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