KR20190042510A - Conductive bonding sheet for fpc and fpc - Google Patents

Abstract

The present invention provides a conductive bonding sheet for FPC and FPC using the same, wherein the conductive bonding sheet for FPC can satisfy conductivity and flame-retardant. The conductive bonding sheet for FPC a support body film and a conductive bonding layer laminated on one surface of the support body film. The conductive bonding layer has a phosphorus-containing resin and silver-coated copper particles as forming materials. Based on 100 parts by mass of the phosphorus-containing resin, the silver-coated copper particles are present in an amount of 100-200 part by mass. Based on 100 parts by mass of the phosphorus-containing resin, the phosphorus-containing resin has 0.2 parts by mass or more of phosphorus. The silver covering rate of the silver-coated copper particles is 80% or more.

Description

FPC CONDUCTIVE BONDING SHEET FOR FPC AND FPC [0002]

The present invention relates to an FPC conductive adhesive sheet and an FPC using the same.

2. Description of the Related Art In a portable electronic device such as a cellular phone or a tablet terminal, electronic components are integrated on a printed circuit board in order to reduce the external size of the case and to facilitate transportation. Further, in order to reduce the size of the outer shape of the case, a printed board is divided into a plurality of parts, and the printed boards are folded or slid by connecting and wiring the divided printed boards using flexible FPCs.

In recent years, in order to prevent malfunction of the electronic device due to the influence of noise of the electromagnetic wave received from the outside of the electronic device or the electromagnetic noise received between the electronic components disposed inside the electronic device, Or an FPC is covered with an electromagnetic wave shielding material.

A conductive adhesive sheet is used for connection between the electromagnetic shielding material and the conductive circuit of the FPC. In addition, a conductive adhesive sheet is used for connection between the metal reinforcing plate and the conductor circuit of the FPC in order to impart electromagnetic shielding to the metal reinforcing plate.

As a technique related to the above-mentioned conductive adhesive sheet, for example, Patent Document 1 describes a curable conductive adhesive composition containing a polyurethane resin, an epoxy resin, an electrically conductive filler, and an additive. The curable conductive adhesive composition described in Patent Document 1 has such a constitution as described above that it is possible to impart appropriate fluidity at the time of bonding and to secure excellent adhesiveness.

International Publication No. 2014/010524

In recent years, the conductive adhesive sheet used for the FPC is required to have high flame retardancy in addition to good conductivity. In order to impart flame retardancy to the conductive adhesive sheet, it can be recalled that a flame retardant is added to the conductive adhesive composition used for the conductive adhesive sheet.

However, as a result of adding the flame retardant to the conductive adhesive composition, the present inventors have found that the conductivity and the flame retardancy are incompatible with each other.

An object of the present invention is to provide an FPC conductive adhesive sheet which can satisfy both conductivity and flame retardancy and which can satisfy higher flame retardancy than conventional ones and an FPC using the conductive adhesive sheet for FPC We will do it.

The present inventors have conducted extensive studies to achieve the above object and as a result, it has been found that by using a conductive adhesive composition containing a resin material and a conductive material in a specific ratio, a conductive adhesive sheet for an FPC satisfying both conductivity and flame retardancy can be obtained .

That is, the present invention employs the following configuration.

[1] A conductive adhesive composition comprising a support film and a conductive adhesive layer laminated on one side of the support film, wherein the conductive adhesive layer comprises a conductive adhesive composition containing a phosphorus-containing resin and silver-coated copper particles, Containing resin contains 100 parts by mass or more and 200 parts by mass or less of the silver-coated copper particles with respect to 100 parts by mass of the phosphorus-containing resin, and the phosphorus-containing resin contains 0.2 parts by mass or more of phosphorus with respect to 100 parts by mass of the phosphorus- Wherein the silver-coated copper particles have a silver coverage of 80% or more.

[2] The conductive adhesive sheet for an FPC according to [1], wherein the combustion time is less than 5 seconds in the flame retardancy evaluation performed under the following conditions.

<Condition>

"Preparation of measurement sample"

Ten sheets of the conductive adhesive sheet for FPC were cut out in a size of 50 mm x 200 mm, and were left for 48 hours under conditions of 23 deg. C and a humidity of 50%, and used as measurement samples.

"Evaluation condition"

The measurement sample prepared according to the above method is wound around a rod having a diameter of 12.7 mm. Thereafter, of the samples wound in a cylindrical shape, a portion within 75 mm from the top is fixed with a pressure sensitive tape, and the rod is pulled out. The upper end of the measurement sample is then sealed so that there is no chimney effect during the measurement. Thereafter, the measurement sample is placed vertically, and a cotton wool is placed 300 mm below the measurement sample. Thereafter, the burner is placed so that the cylinder of the burner is located at a position 10 mm from the lower end of the measurement sample. Thereafter, a blue salt (flame) is applied to the bottom center of the sample for 3 seconds, and the burning time of the measurement sample after the dye transfer is measured. The burning times of the ten measurement samples are made the same, and the average value of the combustion time is calculated.

[3] The conductive adhesive sheet for FPC according to [1] or [2], wherein the silver coverage of the silver-coated copper particles is 95% or more.

[4] The conductive adhesive sheet for FPC according to any one of [1] to [3], wherein the silver-coated copper particles are in a resin (tree)

[5] The conductive adhesive sheet for an FPC according to any one of [1] to [4], wherein the silver-coated copper particles have an average particle diameter of 15 μm or more and 20 μm or less.

[6] The conductive adhesive sheet for an FPC according to any one of [1] to [5], wherein the phosphorus-containing resin is a phosphorus-containing polyurethane resin.

[7] The conductive adhesive sheet for FPC according to [6], wherein the phosphorus concentration of the phosphorus-containing polyurethane resin is 1% by weight or more based on the total amount of the phosphorus-containing polyurethane resin.

[8] The conductive adhesive sheet for an FPC according to any one of [1] to [7], wherein the conductive adhesive resin composition contains silica particles.

[9] The conductive adhesive sheet for an FPC according to any one of [1] to [8], wherein the silica particles have a primary particle diameter of 10 nm or more and 20 nm or less.

[10] The conductive adhesive sheet for an FPC according to any one of [1] to [9], wherein the silica particles are contained in an amount of 1 part by mass to 15 parts by mass with respect to 100 parts by mass of the phosphorus-containing resin.

[11] The conductive adhesive sheet for an FPC according to any one of [1] to [10], wherein the conductive adhesive resin composition contains a silane coupling agent.

[12] An FPC in which the conductive adhesive sheet for an FPC described in any one of [1] to [11] is used for bonding a metal reinforcing plate to the surface of the FPC.

According to the present invention, it is possible to provide an FPC conductive adhesive sheet which can satisfy both conductivity and flame retardancy, and an FPC using the conductive adhesive sheet for FPC.

1 is a schematic cross-sectional view showing an example of a conductive adhesive sheet for an FPC according to the present invention.
Fig. 2 is a schematic cross-sectional view showing an example in which a reinforcing plate is attached to an FPC via the conductive adhesive sheet for FPC according to the present invention.
3 is a schematic sectional view showing a conductive adhesive sheet with a metal reinforcing plate laminated on a metal reinforcing plate with a conductive adhesive layer interposed therebetween.
Fig. 4A is a schematic plan view of a simulated flexible substrate used in the conductivity evaluation method, and Fig. 4B is a sectional view taken along the AA arrow direction in Fig. 4A.
FIG. 5A is a schematic plan view of a test piece for conductivity evaluation used in the evaluation method of conductivity, and FIG. 5B is a cross-sectional view taken along line BB in FIG.
6 is a schematic diagram showing a measurement sample used for evaluation of flame retardancy.
Fig. 7 is a schematic diagram of a test stand for evaluating flame retardancy.

Hereinafter, the present invention will be described based on preferred embodiments.

&Lt; Conductive adhesive sheet for FPC &

The conductive adhesive sheet for FPC used in the FPC of the present invention has a support film and a conductive adhesive layer laminated on one side of the support film, and the conductive adhesive layer is a conductive adhesive composition containing phosphorus-containing resin and silver- (Hereinafter referred to as &quot; adhesive composition &quot;), and the conductive adhesive composition contains 100 parts by mass or more and 200 parts by mass or less of the silver-coated copper particles with respect to 100 parts by mass of the phosphorus- Containing resin contains 0.2 parts by mass or more of phosphorus relative to 100 parts by mass of the phosphorus-containing resin, and the silver-coated copper particles have a silver coverage of 80% or more.

Since the conductive adhesive sheet for FPC of the present invention is formed using an adhesive composition containing a phosphorus-containing resin, it has high flame retardancy. In addition, since silver coated copper particles having a high covering ratio of silver coverage of 80% or more are used, they have high conductivity. Further, since the phosphorus-containing resin and the silver-coated copper particles are contained in a specific ratio, it is possible to provide an FPC conductive adhesive sheet satisfying both of flame retardance and conductivity.

1 is a schematic cross-sectional view showing an example of a conductive adhesive sheet for an FPC according to the present invention.

Fig. 2 is a schematic cross-sectional view showing an example in which a reinforcing plate is attached to an FPC via the conductive adhesive sheet for FPC according to the present invention.

3 is a schematic sectional view showing a conductive adhesive sheet with a metal reinforcing plate laminated on a metal reinforcing plate with a conductive adhesive layer interposed therebetween.

The conductive adhesive sheet 5 for an FPC according to the present invention shown in Fig. 1 is formed by laminating a conductive adhesive layer 4 on a release treatment surface of a support film 1 whose one side has been peeled off. The conductive adhesive layer (4) contains phosphorus-containing resin (2) and silver-coated copper particles (3). 3, the FPC conductive adhesive sheet 5 is laminated on the metal reinforcing plate 6 with the conductive adhesive layer 4 interposed therebetween and then cut to a predetermined dimension, As the conductive adhesive sheet 30, the support film 1 is removed and stored. The conductive adhesive sheet 30 with a metal reinforcing plate is a laminate of a metal reinforcing plate 6 and a conductive adhesive layer 4 and can be used as an electromagnetic wave shielding reinforcing plate for FPC in the embodiment of Fig. 2, the FPC 20 includes a coverlay (not shown) having a mounting component 7 and an earth circuit 9 on a substrate film 8 and an insulating adhesive layer 10 formed on the insulating film 11 12, the earth circuit 9 is protected. The through hole 14 is formed in the cover layer 12 and the conductive adhesive layer 4 of the conductive adhesive sheet 30 with a metal reinforcing plate comes into contact with the earth circuit 9 through the through hole 14, The reinforcing plate 6 functions as an electromagnetic wave shielding member.

The conductive adhesive sheet for FPC of the present invention has high flame retardancy.

Specifically, in the evaluation of the flame retardancy performed under the following conditions, it is preferable that the combustion time is less than 5 seconds.

<Condition>

"Preparation of measurement sample"

Ten sheets of the conductive adhesive sheet for FPC were cut out in a size of 50 mm x 200 mm and left for 48 hours under the conditions of 23 deg. C and a humidity of 50%, thereby obtaining measurement samples.

"Evaluation condition"

The measurement sample prepared according to the above method is wound around a rod having a diameter of 12.7 mm.

Thereafter, of the samples wound in a cylindrical shape, a portion within 75 mm from the top is fixed with a pressure sensitive tape, and the rod is pulled out.

The upper end of the measurement sample is then sealed so that there is no chimney effect during the measurement.

Thereafter, the measurement sample is placed vertically, and a cotton wool is placed 300 mm below the measurement sample.

Thereafter, the burner is placed so that the cylinder of the burner is located at a position 10 mm from the lower end of the measurement sample.

Thereafter, the blue salt is applied to the bottom center of the sample for 3 seconds, and the burning time of the measurement sample after the dye transfer is measured.

The burning times of the ten measurement samples are made the same, and the average value of the combustion time is calculated.

A method of evaluating the evaluation of flame retardancy will be described with reference to the drawings.

Fig. 6 shows a schematic diagram of a measurement sample used for flame retardance evaluation. The conductive adhesive sheet for FPC is cut into a size of 50 mm x 200 mm, and 10 measurement samples 61 are prepared. The measurement sample 61 preferably has a mark 62 at a position of 125 mm in length. The measurement sample thus prepared is placed under the conditions of 23 DEG C and a humidity of 50% for 48 hours to obtain a measurement sample (61).

As shown in Fig. 6, the sample to be measured is reliably wound into a cylindrical shape on a rod 63 having a diameter of 12.7 mm indicated by reference numeral 64. Fig.

A portion of 75 mm from the upper end of the cylindrical measurement sample 61 thus obtained is reliably fixed to the pressure-sensitive tape 74, and then the rod 63 is pulled out. The top of the measurement sample 61 is sealed so that there is no chimney effect during the measurement.

Fig. 7 shows a schematic diagram of a test bench 71 for evaluating flame retardance. A cylindrical measurement sample is vertically installed on the clamp 72 positioned at the tip of the arm 73.

The burner is placed so that the cylinder face is located at a position 10 mm from the lower end of the measurement sample 61 (indicated by reference numeral 76 in Fig. 7) with the cotton woolen face 78 placed 300 mm below the measurement sample 61 75), and the blue salt is applied to the center of the lower end of the sample for 3 seconds.

Thereafter, the burning time of the measurement sample after the dye transfer was measured. The burning times of the ten measurement samples are made the same, and the average value of the combustion time is calculated.

In the present invention, it is preferable that the combustion time measured according to the above method is within 5 seconds.

From the viewpoint of achieving higher flame retardancy, it is more preferable that the time until decontamination is within 4 seconds, and particularly preferably within 3 seconds.

The result of the flame retardancy calculated by this evaluation method indicates that the flame retardancy is higher than that of VTM-0, which is a criterion of flame resistance based on the UL94 standard.

Hereinafter, each material used in the conductive adhesive sheet for FPC of the present invention will be described.

(Support film)

Examples of the support film (1) used in the present invention include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene.

In the case where the support film 1 has, for example, polyethylene terephthalate or the like and has some degree of peelability on the support film itself, the support film 1 is not directly subjected to the peeling treatment, ) May be laminated. The surface of the support film 1 may be subjected to a peeling treatment so as to make the conductive adhesive layer 4 more easily peeled off from the support film 1.

When the resin film used as the support film 1 does not have peelability, a peeling agent is applied by applying a releasing agent such as aminoalkyd resin or silicone resin, followed by heating and drying. Since the FPC conductive adhesive sheet (5) of the present invention is bonded to an FPC, it is preferable not to use a silicone resin for the releasing agent. This is because when a silicone resin is used as a releasing agent, a part of the silicone resin is transferred to the surface of the conductive adhesive layer 4 that is in contact with the surface of the support film 1, There is a risk of shifting to the other side of the layer 4. There is a possibility that the silicone resin transferred to the surface of the conductive adhesive layer 4 weakens the adhesive strength of the conductive adhesive layer 4 to the metal reinforcing plate 6. [

The thickness of the support film 1 used in the present invention is not particularly limited because it is excluded from the thickness of the conductive adhesive layer 4 when it is used by being adhered to an FPC, and usually about 12 to 150 mu m.

(Peeling film)

In the conductive adhesive sheet 5 for an FPC according to the present invention shown in Fig. 1, a conductive adhesive layer 4 is laminated on one surface of a support film 1. Fig. The conductive adhesive sheet 5 for an FPC according to the present invention is characterized in that a conductive adhesive layer 4 is laminated on one side of a support film 1 and a release film obtained by laminating a release agent layer on one side of the base material, The conductive adhesive agent layer 4 may be bonded to the surface of the conductive adhesive layer 4 via the adhesive layer 4.

Examples of the base material of the release film include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. These resin films are coated with a releasing agent such as aminoalkyd resin or silicone resin, and then dried by heating to carry out the peeling treatment. Since the conductive adhesive sheet for FPC of the present invention is bonded to an FPC, it is preferable not to use a silicone resin for the releasing agent. When a silicone resin is used as a releasing agent, a part of the silicone resin is transferred to the surface of the conductive adhesive layer in contact with the surface of the release film, and the support film 1 is peeled from the conductive adhesive layer through the inside of the conductive adhesive sheet for FPC, There is a risk of transition. There is a possibility that the silicone resin transferred to the surface of the conductive adhesive layer weakens the adhesive force of the conductive adhesive layer. The thickness of the release film used in the present invention is not particularly limited, but is usually about 12 to 150 mu m.

&Quot; Conductive adhesive composition &quot;

The conductive adhesive composition used for forming the conductive adhesive layer of the conductive adhesive sheet for FPC of the present invention will be described. The adhesive composition contains a phosphorus-containing resin and silver-coated copper particles in a specific ratio.

[Phosphorus Containing Resin]

The phosphorus-containing resin used in the present invention may be a phosphorus-containing resin containing phosphorus in the molecule (hereinafter referred to as "introduction type"), and a phosphorus-containing resin to which a phosphorus- Blended type &quot;).

The introduction-type phosphorous-containing resin means a resin having a structure in which a phosphorus atom is introduced into a main chain structure or a side chain structure.

For example, a phosphorus-containing polyester resin derived from a compound containing phosphorus in its structure, a phosphorus-containing polyurethane resin, and a phosphorus-containing epoxy resin can be given. Among them, a phosphorus-containing polyurethane resin is preferable.

From the viewpoint of obtaining higher flame retardancy, the introduction type phosphorus-containing resin preferably contains phosphorus in an amount of 0.2 parts by mass or more based on 100 parts by mass of the phosphorus-containing resin, preferably 1% by mass or more, Or more, and particularly preferably 2.0 wt% or more. The upper limit value is preferably 10% by weight or less, more preferably 5% or less. If the content of phosphorus is less than the above lower limit value, flame retardancy can not be sufficiently exhibited, and it becomes difficult to obtain a flame-retardant conductive adhesive sheet for FPC.

In the present specification, the "phosphorus content" means the weight ratio of the phosphorus element itself in the resin.

Examples of the blended phosphorus-containing resin include a phosphorus-based flame retardant added to a resin such as an epoxy resin, an acrylic resin, a polyester resin, a polyimide resin or a polyurethane resin. Of these, phosphorus- Containing resin is preferable.

In the present invention, a phosphorus-containing resin containing phosphorus in a molecule is preferable from the viewpoint of imparting higher flame retardancy, and phosphorus-containing polyurethane resin is particularly preferable among them.

From the viewpoint of obtaining a higher flame retardancy, the blended phosphorus-containing resin preferably contains 0.2 parts by mass or more of a phosphorus-containing flame retardant per 100 parts by mass of the phosphorus-containing resin, preferably 1% by mass or more, More preferably not less than 10% by weight, and particularly preferably not less than 2.0% by weight. If the content of the phosphorus flame retardant is less than the above lower limit value, flame retardancy can not be sufficiently exhibited, and it becomes difficult to obtain a flame-retardant conductive adhesive sheet for FPC.

[Silver-coated copper particles]

The silver-coated copper particles used in the present invention preferably have a silver coverage of 80% or more, more preferably 90% or more, and more preferably 95% or more, from the viewpoint of obtaining higher conductivity.

As used herein, the term &quot; silver-coated copper particles &quot; means particles having a core shell structure in the present invention, wherein the core does not substantially contain silver, while the shell means silver. For silver coated copper particles, the silver shell is a coating or layer that at least partially covers the core.

In the present invention, the silver-coated copper particles to be used are conductive particulate materials and may have various shapes such as spherical, planar, flake, and dendrite. In the present invention, the silver-coated copper particles are preferably in the form of a resin.

In the method of setting the silver coverage of the coated copper particles to the above specific range, a silver-coated copper particle material which achieves the above specific silver coverage may be purchased, and the silver precipitation time To obtain silver-coated copper particles that achieve the specified silver coverage.

In the present invention, the silver-coated copper particles preferably have an average particle diameter of 15 mu m or more and 20 mu m or less.

In the present invention, the &quot; average particle diameter &quot; is a value obtained by measuring the size of particles in a suspension or emulsion of silver-coated copper particles using the diffraction of a laser beam.

When the coated copper particles are spherical, the average particle diameter can be calculated from the value obtained by measuring the diameter of the spheres. When the coated copper particles have a shape such as normal, flake or dendrite, the average particle diameter is calculated from the value obtained by measuring the longest diameter .

In the present invention, the adhesive composition contains 100 parts by mass or more and 200 parts by mass or less of silver-coated copper particles per 100 parts by mass of the phosphorus-containing resin, more preferably 110 parts by mass or more and 190 parts by mass or less, And particularly preferably not less than 185 parts by mass.

The conductive adhesive sheet for FPC of the present invention can achieve both conductivity and flame retardance by using an adhesive composition having a blending ratio of phosphorus-containing resin and silver-coated copper particles within the above-specified range.

[Silica particles]

In the present invention, it is preferable that the adhesive resin composition contains silica particles. By containing the silica particles in the adhesive resin composition, it is possible to prevent the silver-coated copper particles from precipitating. Further, since the cohesive force of the adhesive resin composition can be improved, heat resistance of the conductive adhesive sheet for FPC and adhesion with the substrate can also be improved.

In the present invention, the primary particle diameter of the silica particles is preferably 10 nm or more and 20 nm or less, more preferably 12 nm or more and 18 nm or less.

The content of the silica particles in the adhesive composition is preferably 1 part by mass or more and 15 parts by mass or less, more preferably 5 parts by mass or more and 14 parts by mass or less, based on 100 parts by mass of the phosphorus containing resin.

[Silane coupling agent]

In the present invention, it is preferable that the adhesive resin composition contains a silane coupling agent. When the adhesive resin composition contains a silane coupling agent, adhesion performance can be improved.

[Other components]

In the present invention, other thermosetting resins, thermoplastic resins and the like can be added in addition to the above components. In addition, additives such as a curing accelerator, a polymerization inhibitor, a sensitizer, a flame retardant, and a thixotropic agent may be contained.

Above all, as the crosslinking agent, an epoxy resin having two or more functionalities is preferable. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolak type epoxy resins, and glycidyl amine type. Among them, a polyfunctional epoxy resin is preferable from the standpoint of heat resistance. EPICLON (registered trademark) N-740, EPICLON N-770 (manufactured by DIC Corporation), YDPN-638 (manufactured by Mitsubishi Kagaku Kogyo K.K.), and the like can be used as the polyfunctional epoxy resin. Examples of the polyfunctional epoxy resin include jER (registered trademark) 154, jER157, jER1031, jER1032 , YDCN-700, YH-434 (Shinnitetsu Sumikin Chemical Co., Ltd.), TETRAD (registered trademark) -X, and TETRAD-C (Mitsubishi Gas Chemical Co., Ltd.).

<FPC>

In the FPC of the present invention, the conductive adhesive sheet for FPC of the present invention is used for bonding the metal reinforcing plate to the surface of the FPC.

INDUSTRIAL APPLICABILITY The conductive adhesive sheet for FPC of the present invention can improve the efficiency of the work process of bonding the conductive adhesive sheet with the metal reinforcing plate to the FPC, contributes to the improvement of the productivity, and is of great industrial value.

Example

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

&Lt; Preparation of conductive adhesive composition &gt;

The components shown in Table 1 below were mixed to obtain Conductive Adhesive Compositions of Compositions 1 to 9 and Comparative Compositions 1 to 4.

More specifically, silver-coated copper particles, silane coupling agent, silica particles and a crosslinking agent in the respective mixing ratios shown in Table 1 were added to 250 parts by mass of a 40% solution of the phosphorus-containing resin (100 parts by mass of the resin component) Diluted with ethyl ketone and toluene, and stirred to obtain a conductive adhesive composition.

In Table 1, each component means the following materials. The numerical values in [] in Table 1 are compounding ratios (parts by mass). In Table 1, &quot; phosphorus content &quot; is the weight ratio of phosphorus element itself to the total amount of phosphorus-containing polyurethane resin.

(A) -1: phosphorus-containing polyurethane (trade name "UR-3575" (flame retardant polyurethane resin, phosphorus concentration: 2.5%, acid value: 10 KOHmg / g)

(A) -2: phosphorus-containing resin added with phosphorus flame retardant to polyurethane

(A) -3: polyurethane

Silver coated copper particles: silver coated copper (RM-D10, manufactured by Toda Kogyo Co., Ltd.)

Silane coupling agent: KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.

Silica particles: "R972" (hydrophobic fumed silica) manufactured by Japan Aerosil Co., Ltd.,

Crosslinking agent: manufactured by TOYOBO, trade name "HY-30"

&Lt; Preparation of conductive adhesive sheet for FPC &

A polyethylene terephthalate (PET) film having a thickness of 50 탆 and subjected to a peeling treatment on one side thereof was used as the support film 1.

Each of the conductive adhesive compositions of the compositions 1 to 9 and the comparative compositions 1 to 4 obtained above was coated on the release surface of the support film 1 so that the thickness after drying was measured by a dial gauge to be 40 占 퐉, , Followed by heating and drying for 3 minutes to obtain a conductive adhesive sheet for FPCs of Examples 1 to 9 and Comparative Examples 1 to 4.

&Quot; Evaluation of conductive adhesive sheet for FPC &

The following evaluations were carried out on the obtained conductive adhesive sheets for FPCs of Examples 1 to 9 and Comparative Examples 1 to 4.

[Evaluation of Flame Retardancy]

The conductive adhesive sheets for FPCs of Examples 1 to 9 and Comparative Examples 1 to 4 were subjected to a combustion test.

As shown in Fig. 6, the conductive adhesive sheet for FPC was cut into a size of 50 mm x 200 mm, and 10 measurement samples 61 were prepared. The measurement sample 61 described the mark 62 at a position of 125 mm in height. The prepared measurement sample was placed under the conditions of 23 캜 and 50% humidity for 48 hours to obtain a measurement sample (61).

As shown in Fig. 6, the sample to be measured was surely wound into a cylindrical shape on the rod 63 having a diameter of 12.7 mm, which is indicated by the numeral 64. Fig.

A portion of 75 mm from the upper end of the cylindrical measurement sample 61 was securely fixed with the pressure sensitive tape 74 and then the rod 63 was pulled out. The top of the measurement sample 61 was sealed so that there was no chimney effect during the measurement.

A measurement sample in the form of a cylinder was vertically installed on a clamp 72 located at the tip of the arm 73 of the test bench 71 shown in Fig.

The burner is placed so that the cylinder face is located at a position 10 mm from the lower end of the measurement sample 61 (indicated by reference numeral 76 in Fig. 7) with the cotton woolen face 78 placed 300 mm below the measurement sample 61 75) was placed, and the blue salt was applied to the bottom center of the sample for 3 seconds.

Thereafter, the burning time of the measurement sample after the dye transfer was measured. The burning times of the 10 measurement samples were made to be the same, and the average value of the combustion time was calculated and evaluated according to the following evaluation criteria.

?: The average value of the combustion time was 3 seconds or less.

?: The average value of the combustion time was longer than 3 seconds and less than 5 seconds.

X: The average value of the combustion time was longer than 5 seconds.

[Adhesion]

The conductive adhesive layer 4 side of the conductive adhesive sheet for FPC was laminated on a metal reinforcing plate made of SUS foil having a thickness of 30 탆 (made by Nissin Steel Co., Ltd., material: SUS304) at a temperature of 140 캜 for 1 m / min After the heat lamination, the support film 1 was peeled off and the conductive adhesive sheet for FPC was cut to dimensions of 50 mm x 120 mm. A polyimide film (manufactured by Toray DuPont Co., Ltd., product number: 200H) having a thickness of 50 占 퐉 was laminated on the electrically conductive adhesive sheet with the cut metal reinforcing plate facing the conductive adhesive layer side and hot pressed at 160 占 폚 and 2.5 MPa for 60 minutes, A test piece was obtained. The SUS thin side of 30 占 퐉 in thickness was fixed with a supporting mechanism in accordance with 8.1.1 Method A (90 占 peeling off) of JIS-C-6471 &quot; Test Method for Copper Laminates for Flexible Printed Circuit Boards &quot; A sample having a peel force of 10 N / cm or more was evaluated as &quot;? &Quot;, a sample having a peel strength of 5 N / cm or more and 10 N / cm or less was evaluated as & The sample is designated &quot; X &quot;

[Conductivity]

The conductive adhesive layer 4 side of the FPC conductive adhesive sheet 5 was laminated on one surface of a metal reinforcing plate 6 made of an SUS foil having a thickness of 30 占 퐉 (made by Nissin Steel Co., Ltd., material: SUS304) After heat-lamination under the conditions of 140 캜 and 1 m / min, the support film 1 was peeled to a size of 15 mm in width × 100 mm in length, and the conductive adhesive sheet 30 with a metal reinforcing plate was obtained.

4, rectangular copper foil pieces 9 each having a width of 5 mm and a length of 50 mm were arranged in a line at intervals of 30 mm on a substrate film 8 made of a polyimide film, Of copper foil were placed to prepare a simulated flexible substrate.

5, a portion of the rectangular copper foil 9 of the simulated flexible substrate is covered with a coverlay film 12 having a through hole 14 having a diameter of 1.5 mm, and the through hole 14 , The conductive adhesive sheet 30 with a metal reinforcing plate was temporarily fixed and hot-pressed at 160 DEG C and 2.5 MPa for 60 minutes to obtain a test piece for conductivity evaluation. Next, the electrical resistance between the portion of the simulated flexible substrate on which the copper foil piece 9 was exposed and the metal reinforcing plate 6 of the conductive adhesive sheet 30 with a metal reinforcing plate was measured with a digital multimeter A sample having an electric resistance of less than 0.5? Was rated (?), A sample having an electrical resistance of 0.5? Or more to less than 1.0? (?), And a sample having an electrical resistance of 1.0?

[Resin fluidity]

Whether there was no resin flow at the end of the simulated flexible substrate obtained by the above conductivity evaluation was confirmed using a microscope with a magnification of 200 times. A sample having a push-out of less than 100 占 퐉 by resin flow (?), A sample of pushing out by resin flow of not less than 100 占 퐉 and less than 150 占 퐉 (?), .

[My blocking ability]

The conductive adhesive layer 4 side of the conductive adhesive sheet for FPC was laminated on a polyimide film (manufactured by Toray DuPont Co., Ltd., product number: 100H) having a thickness of 25 占 퐉 to face each other and heat laminated at 140 占 폚 and 1 m / Then, the support film 1 was peeled off and cut into dimensions of 90 mm x 140 mm. The cut conductive adhesive sheet with the polyimide film was fixed to the SUS plate, and a load of 5 kg was placed thereon, and left at room temperature for 1 hour to prepare a sample. The conductive adhesive sheet with polyimide film was peeled off from the SUS plate according to Method B (180 ° direction peeling) of 8.1.1 of "Test Method for Copper Laminates for Flexible Printed Circuits" in JIS-C-6471, / 50 mm) was measured. A sample having a peeling force of less than 100 mN / 50 mm was evaluated as &amp; cir &amp;

This evaluation method replaces the conductive adhesive sheet (conductive adhesive layer side) with one metal reinforcing plate by a conductive adhesive sheet with a polyimide film as a model of the blocking phenomenon caused when the conductive adhesive sheets with two metal reinforcing plates are laminated , And another conductive adhesive sheet with a metal reinforcing plate (metal reinforcing plate side) is substituted with an SUS plate.

As shown in the results, the conductive adhesive sheets for FPC according to Examples 1 to 9 to which the present invention was applied had both flame retardance and conductivity, and also had good adhesion.

Evaluation was made in Example 8, but since the diameter of the silver-coated copper particles was large and the formed adhesive layer contained air, the comprehensive evaluation was called &quot;? &Quot;.

Examples 1 to 8 using phosphorus-containing polyurethane containing phosphorus in the molecule showed higher flame retardancy than Example 9 using a phosphorus-containing resin to which phosphorus-containing flame retardant was added to polyurethane.

On the other hand, in Comparative Example 1, the amount of the silver-coated copper particles was large and the adhesion was remarkably poor. In Comparative Examples 2 to 4, flame retardancy was not good. In Comparative Examples 1 to 4, to which the present invention was not applied, flame retardancy and conductivity could not be compatible at all.

One… Support film, 2 ... Phosphorus-containing resin, 3 ... Coated copper particles, 4 ... Conductive adhesive layer, 5 ... Conductive adhesive sheet for FPC, 6 ... Metal reinforcing plate, 7 ... Mounting parts, 8 ... Substrate film, 9 ... Earth circuit (copper flake), 10 ... Insulating adhesive layer, 11 ... Insulation film, 12 ... Cover Ray 14 ... Through hole, 20 ... FPC, 30 ... Conductive adhesive sheet with metal reinforcing plate, 61 ... Measurement sample, 62 ... Mark, 63 ... Rods, 64 ... Diameter of the rod, 74 ... Pressure sensitive tape, 71 ... Test bed, 72 ... Clamp, 73 ... Arm, 78 ... Cotton wool, 76 ... Position of padding, 75 ... burner.

Claims (6)

A support film and a conductive adhesive layer laminated on one side of the support film,
Wherein the conductive adhesive layer comprises a conductive adhesive composition containing a phosphorus-containing resin and silver-coated copper particles as a forming material,
Wherein the conductive adhesive composition contains 100 parts by mass or more and 200 parts by mass or less of the silver-coated copper particles and not more than 5.81 parts by mass of a crosslinking agent with respect to 100 parts by mass of the phosphorus-
Wherein the phosphorus-containing resin contains phosphorus in an amount of 0.2 parts by mass or more based on 100 parts by mass of the phosphorus-
Wherein the silver-coated copper particles have a silver coverage of 80% or more. The method according to claim 1,
Wherein the phosphorus-containing resin is a phosphorus-containing polyurethane resin. 3. The method of claim 2,
Wherein the phosphorus concentration of the phosphorus-containing polyurethane resin is at least 1 wt% of the total phosphorus-containing polyurethane resin. 4. The method according to any one of claims 1 to 3,
Wherein the conductive adhesive composition contains silica particles. 4. The method according to any one of claims 1 to 3,
Wherein the conductive adhesive composition contains a silane coupling agent. An FPC in which the conductive adhesive sheet for an FPC according to any one of claims 1 to 3 is used for bonding a metal reinforcing plate to the surface of an FPC.

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