KR20060082043A - Flexible printed wiring board, multilayer flexible printed wiring board and portable telephone terminal using the multilayer flexible printed wiring board - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible printed wiring board and a multilayer flexible printed wiring board capable of maintaining sufficient flex resistance by preventing adhesion of the FPC substrate to the bent portion in a method of laminating a substrate having a non-bonded portion and an adhesive portion. have.

The present invention is composed of at least an electrical insulation layer and a conductor layer, wherein the ten-point average roughness of the surface of the electrical insulation layer is 1.5 µm or more and less than 2.0 µm, and the contact angle is 60 ° or more and less than 120 °, or 10-point average. The roughness is not less than 2.0 µm and less than 4.0 µm. The two or more flexible printed wiring boards and flexible printed wiring boards are laminated, bendable, and the surface of the electrically insulating layer of two or more exposed flexible printed wiring boards is opposed to each other, and It is an adhesive state and a part of the said wiring board provides the multilayer flexible printed wiring board laminated | stacked on the 1st multilayer wiring board and the 2nd multilayer wiring board, respectively.

Flexible printed wiring board, insulation layer, conductor layer, contact angle, adhesive layer

Description

FLEXIBLE PRINTED WIRING BOARD, MULTILAYER FLEXIBLE PRINTED WIRING BOARD AND PORTABLE TELEPHONE TERMINAL USING THE MULTILAYER FLEXIBLE PRINTED WIRING BOARD}

1 is a schematic diagram showing a folding cellular phone.

2 is a schematic diagram showing an example of use of an FPC substrate in a mobile telephone.

3 is a cross-sectional view showing an example of a multilayer FPC substrate.

4 is a cross-sectional view showing the flexible printed wiring board of the first embodiment.

Fig. 5 is a sectional view showing the flexible printed wiring board of the second embodiment.

Fig. 6 is a cross-sectional view showing the flexible printed wiring board of the third embodiment.

Fig. 7 is a sectional view showing the multilayer flexible printed wiring board of the fourth embodiment.

FIG. 8 is a structural diagram showing a multilayer flexible printed wiring board of a fifth embodiment; FIG.

9 is an explanatory diagram of a method for measuring a surface contact angle in an example.

10 is an explanatory diagram of an evaluation method of adhesion in an example (two-layer substrate).

11 is an explanatory diagram of a method for evaluating adhesion in an example (three-layer substrate).

<Explanation of symbols for the main parts of the drawings>

10, 30: housing

20: hinge part

42: electrical insulation layer

43: conductor layer

51: adhesive layer

60: adhesive sheet

100, 300: circuit board

200: FPC board

400: multilayer FPC

600 to 630: multilayer flexible printed wiring board

700: Coverlay

710, 810, 910: electrical insulation layer

800, 900: flexible printed wiring board

811: electrically insulating resin

812: Filler

820, 930: Conductor layer

720, 920: adhesive layer

[Document 1] Japanese Unexamined Patent Application Publication No. 7-312469

The present invention relates to a flexible printed wiring board, a multilayer flexible printed wiring board, and a mobile phone terminal using the multilayer flexible printed wiring board.

In recent years, the spread of mobile telephone terminals (hereinafter also referred to as mobile telephones) has been rapidly progressing. Along with this, the demand for folding cellular phones has also increased for the purpose of making the cellular phones more compact. A schematic diagram of a folding cellular phone is shown in FIG. As shown in FIG. 1, the folding cellular phone is configured to rotatably connect the first housing 10, the second housing 30, and the first housing 10 and the second housing 30, respectively. It has the structure which has the hinge part 20. As shown in FIG. In addition, the folding cellular phone can move in the direction of the arrow shown in FIG.

By the way, since flexible printed wiring board (henceforth FPC board | substrate) has the outstanding flexibility and flexibility, it is widely used for portable electronic devices, especially a mobile telephone.

In addition, the FPC board | substrate (henceforth a 3-layer board | substrate here) is provided with an adhesive layer in the one or both surfaces of electrical insulation layers, such as a polyimide film, for example, and laminates conductor layers, such as copper foil, for example. The thing which adhered or the said laminated lamination, the circuit layer formed with the circuit and laminated | stacked further the coverlay which consists of an electrical insulation layer, such as a polyimide film, and an adhesive bond layer, for example is said. In addition, an FPC two-layer board | substrate (henceforth a two-layer board | substrate) is what apply | coated and hardened | cured after apply | coating the electrical insulation layer, such as polyimide, to the conductor layer, such as copper foil, or a coverlay to the conductor layer formed by circuit, for example. Also refers to a laminate attached. In addition, a multilayer flexible printed wiring board (henceforth a multilayer FPC board | substrate) means what laminated | stacked and attached two or more layers of several FPC board | substrates or two-layer board | substrate with various deformation | transformation through an adhesive layer.

Here, an example is shown in FIG. 2 as a use example of an FPC board | substrate to a mobile telephone. As shown in FIG. 2, the FPC board 200 serves to electrically connect the circuit board 100 embedded in the housing 10 and the circuit board 300 embedded in the housing 30.

BACKGROUND ART In recent years, circuit boards assembled in mobile telephones are accompanied by high functionality and miniaturization of mobile telephones, resulting in higher wiring density of circuit boards themselves, and multilayered circuit boards. For this reason, for example, the circuit boards 100 and 300 embedded in the housings 10 and 30 are also multilayered, and the FPC board 200 connecting the housing 10 and the housing 30 is also connected to a plurality of FPC boards. The case is increasing.

As a method of connection, the circuit board 100 and the circuit board 300 are separately integrated, and in order to connect these two, the connection method by a connector via the FPC board 200, and the circuit boards 100 and 300 are connected. ) And the FPC board 200 are integrated into a multi-layer FPC board.

Here, an example of a multilayer FPC board | substrate is shown in FIG.

As shown in FIG. 3, the multilayer FPC 400 includes a circuit board 100, a circuit board 300, and an FPC board 200 positioned between the circuit board 100 and the circuit board 300. 3, although the circuit board 100 is abbreviate | omitted in illustration, it has the same layer structure as the circuit board 300, and has a structure with a different circuit pattern. For example, if the circuit board 300 of FIG. 3 has six layers, the circuit board 100 also has six layers, but the circuit pattern has a different structure from the circuit board 300 and the circuit board 100.

The circuit boards 100 and 300 are formed by stacking a plurality of FPC boards 70 (hereinafter also referred to simply as FPC boards 70) and adhesive sheets 60 with coverlays. The FPC substrate 70 is composed of an FPC substrate 40 composed of an electrically insulating layer 42 and an adhesive layer 41 and a conductor layer 43 formed in a circuit, and a coverlay 50 covering the conductor layer 43. . In addition, the coverlay 50 consists of an electrical insulation layer 52 and the adhesive bond layer 51. The FPC board 200 generally consists of the FPC board 70.

By the way, the multilayer FPC board | substrate is an integral multilayer FPC board | substrate which does not provide a connection part in order to achieve high density and thickness reduction.

In addition, in order to ensure sufficient flexibility (flexibility) with respect to the bent portion of the integrated multilayer FPC substrate, only the circuit board portion is laminated and adhered without bonding between the FPC substrate and the FPC substrate.

The structure which provided the non-junction part so that the insulating layers in the bending part of such a multilayer flexible circuit board do not join is disclosed (patent document 1).

However, in the manufacturing method of the integral multilayer FPC board | substrate, in order to laminate | paste together by heat press processing of about 140-200 degreeC * 20-50kgf / cm <2>, for example, FPC of connection parts does not need to interpose an adhesive sheet etc. Is in close contact with each other, and sufficient flexibility cannot be maintained (in other words, sufficient flex resistance cannot be exhibited). In addition, conventionally, in order to solve this problem, the contact | adherence FPC board | substrate was peeled off by one sheet by manpower. Thereby, there also existed a problem that manufacturing cost became large.

[Patent Document 1] Japanese Patent Application Laid-Open No. 7-312469

The problem to be solved by the present invention is to solve the above problems of the prior art.

Accordingly, an object of the present invention is to provide a flexible printed wiring board and a multilayer flexible printed wiring board which can maintain a sufficient flex resistance by preventing adhesion of the FPC substrate to the bent portion in a method of laminating a substrate having a non-bonded portion and an adhesive portion. There is.

According to the 1st aspect of this invention, it is a flexible printed wiring board which consists of an electrical insulation layer and a conductor layer at least, The ten-point average roughness of the said electrical insulation layer surface is 1.5 micrometers or more and less than 20 micrometers, and a contact angle is 60 degrees. A flexible printed wiring board is provided, characterized in that the average roughness is not less than 120 ° or less, or the ten point average roughness is 2.0 μm or more and less than 4.0 μm. Thereby, even in the lamination | stacking method of the board | substrate which has a non-bonded part and an adhesive part by high temperature heating press, since the uneven | corrugated shape or surface functional number of the surface of the said electrical insulation layer is small, adhesion of the said electrically insulating layer is prevented, respectively, Flexibility of the flexible printed wiring board is maintained to improve the flex resistance.

It is preferable that said electrical insulation layer consists of polyimide. Thereby, even the lamination | stacking method of the board | substrate which has a non-bonded part and an adhesive part by high temperature heat pressurization has sufficient heat resistance and flexibility.

According to the second aspect of the present invention, there is provided a flexible printed wiring board comprising at least an electrical insulation layer, an adhesive layer, and a conductor layer, wherein the ten-point average roughness of the surface of the electrical insulation layer is 1.5 µm or more and less than 2.0 µm, Also provided is a flexible printed wiring board, characterized in that the contact angle is greater than or equal to 60 ° and less than or equal to 120 °, or that the ten point average roughness is greater than or equal to 2.0 µm and less than or equal to 4.0 µm. Thereby, even in the lamination | stacking method of the board | substrate which has a non-bonded part and an adhesive part by high temperature heating press, since the uneven | corrugated shape or surface functional number of the surface of the said electrical insulation layer is small, adhesion of the said electrically insulating layer is prevented, respectively, Flexibility of the flexible printed wiring board is maintained to improve the flex resistance.

It is preferable that said electrical insulation layer consists of polyimide. Thereby, even the lamination | stacking method of the board | substrate which has a non-bonded part and an adhesive part by high temperature heat pressurization has sufficient heat resistance and flexibility.

According to the 3rd aspect of this invention, the coverlay which consists of an adhesive bond layer and an electrical insulation layer is a flexible printed wiring board provided in the conductor layer, and the ten-point average roughness of the electrical insulation layer surface in the said coverlay is 1.5. A flexible printed wiring board is provided, characterized in that the contact angle is at least 60 to less than 2.0 and the ten point average roughness is at least 2.0 to less than 4.0 m. Thereby, even in the lamination | stacking method of the board | substrate which has a non-bonded part and an adhesive part by high temperature heating press, since the uneven | corrugated shape or surface functional number of the surface of the said electrical insulation layer is small, the adhesion of the opposing electrical insulation layer is prevented, respectively, Flexibility of the flexible printed wiring board is maintained to improve the flex resistance.

According to the fourth aspect of the present invention, there is provided a multilayer flexible printed wiring board in which two or more flexible printed wiring boards are laminated, and in an bendable state, the surface of the electrically insulating layer of two or more exposed flexible printed wiring boards is opposed to each other. And a non-adhesive state, wherein a part of the flexible printed wiring board is laminated on each of the first multi-layer flexible printed wiring board and the second multi-layer flexible printed wiring board. This maintains the flexibility of the flexible printed wiring board and improves the flex resistance.

According to the fifth aspect of the present invention, in a mobile phone terminal having a hinge portion rotatably connecting the first housing and the second housing, the bent portion of the multilayer flexible printed wiring board according to claim 6 passing through the hinge portion is provided. There is provided a mobile phone terminal using a multilayer flexible printed wiring board, wherein the surface of the electrically insulating layer of two or more exposed flexible printed wiring boards is opposed to each other and is in a non-adhesive state. This maintains the flexibility of the flexible printed wiring board and improves the flex resistance of the mobile phone terminal.

Moreover, this invention is a laminated board with a metal used for the said flexible printed wiring board or the said mobile telephone terminal, Comprising: The electrical insulation layer and the conductor layer before circuit formation are provided, The 10-point average roughness of the surface of the said electrical insulation layer is 1.5 micrometers. Provided is a laminate with a metal, characterized in that the above-mentioned to less than 2.0 ㎛, the contact angle is more than 60 ° to less than 120 °, or 10 point average roughness is 2.0 ㎛ or more and less than 4.0 ㎛.

Moreover, this invention is a coverlay used for the said flexible printed wiring board of the said 3rd, 4th form, or the said mobile telephone terminal, consists of an adhesive bond layer and an electrical insulation layer, and 10-point average roughness of the surface of the said electrical insulation layer is carried out. Is 1.5 μm or more and less than 2.0 μm, and the contact angle is 60 ° or more and less than 120 °, or a 10-point average roughness is 2.0 μm or more and less than 4.0 μm.

In addition, the concept of the said invention does not enumerate all about the characteristic required for this invention, and its combination can also be invention.

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated through embodiment of this invention, the following embodiment is not limited to the invention regarding a claim, and all the feature combinations demonstrated in embodiment are in the solution means of invention. It is not necessarily required.

(Flexible Printed Wiring Board of First Embodiment)

As a flexible printed wiring board of this invention, it is a flexible printed wiring board which consists of an electrical insulation layer and a conductor layer at least as a 1st embodiment, The ten-point average roughness of the surface of the said electrical insulation layer is 1.5 micrometers-2.0 micrometers, Also provided is a flexible printed wiring board, characterized in that the contact angle is greater than or equal to 60 ° and less than or equal to 120 °, or that the ten point average roughness is greater than or equal to 2.0 µm and less than or equal to 4.0 µm.

4 is a cross-sectional view of the flexible printed wiring board of the first embodiment.

In FIG. 4, the flexible printed wiring board 800 includes a conductor layer 820 and an electrical insulation layer 810.

The electrical insulation layer 810 in 1st Embodiment is comprised from the resin composition which has the electrically insulating resin 811 and the filler 812 as an essential component.

In addition, the surface of the electrical insulation layer 810 has a 10-point average roughness of 1.5 µm or more and less than 2.0 µm, and a contact angle of 60 ° or more and less than 120 °, or a 10-point average roughness of 2.0 µm or more and less than 4.0 µm. To form.

Accordingly, in the case where a plurality of flexible printed wiring boards are laminated, even if the method of laminating a substrate having a non-bonded portion and an adhesive portion by heating and pressing at about 140 to 200 ° C. × 20 to 50 kgf / cm 2, for example, By using the flexible printed wiring board, since the adhesion of the opposing electrical insulating layers is prevented, the flexibility of each flexible printed wiring board is maintained and the flex resistance is improved.

Moreover, when shape | molding below the said heating temperature, other characteristics, such as a circuit embedding property and adhesiveness fall, are not fully exhibited, for example.

As a method of providing the uneven shape on the surface of the present electrical insulating layer 810, the method of forming the uneven shape on the surface of the electrical insulating layer 810 by providing the resin composition on the conductor layer 820 (hereinafter, referred to as a filler) And the electrical insulation layer 810 on the conductor layer 820, and then, for example, by a physical method such as sandblasting to blow fine particles and roughen the surface shape. There is a method of forming an uneven shape on the surface of the insulating layer 810 (hereinafter also referred to as surface roughening method).

The uneven | corrugated shape of the surface of the electrical insulation layer 810 of 1st Embodiment of this invention was formed by the filler addition method.

In the filler addition method, it has become apparent from various experiments that the amount of filler added affects the uneven shape of the surface shape. The amount of the filler 812 added is preferably 0.2 to 20 parts by weight, more preferably 0.2 to 10 parts by weight based on the weight part of the electrically insulating resin 100 after curing molding. When the added amount of the filler 812 is less than 0.2 part by weight, sufficient surface irregularities cannot be formed on the surface of the electrical insulation layer, and when the opposing electrical insulation layers are heated and pressurized, the electrical layers are in close contact with each other, thereby providing sufficient flexibility. It cannot be obtained, and it cannot exhibit flex resistance. In addition, when it is 20 weight part or more, desired characteristics, such as an electrical property, cannot be exhibited, for example.

As the electrically insulating resin 811, for example, a resin having insulating properties such as polyimide, polyamide, and polyamideimide is employed, and polyimide is particularly preferable from the viewpoint of heat resistance.

As the filler 812, inorganic fine particles such as calcium hydrogen phosphate, silica, talc and alumina are employed, and calcium hydrogen phosphate is particularly preferable from the viewpoints of dispersibility and particle hardness in the resin. Preferably the particle size of a filler is 0.5-5 micrometers, and it is more preferable that it is 1-3 micrometers from a manufacturing viewpoint, such as a coating process.

As the conductor layer 820, metal foil, such as copper, silver, aluminum, etc. are used, for example. If the thickness of the metal foil is within the range of the thickness used in the field, there is no problem in particular.

Moreover, you may add various additives, for example, a leveling agent, a coupling agent, an antifoamer, etc. to the said resin composition as needed in the range which does not reduce various characteristics.

As a coating method of the said electrical insulation layer of this embodiment, said resin composition is apply | coated on a conductor layer by application | coating methods, such as a comma coater, a die coater, a gravure coater, and electric insulation by heat-hardening after that. Form a layer.

Moreover, the electrical insulation layer may provide the layer which consists only of electrically insulating resin on the single layer of the resin composition which consists of electrically insulating resin and a filler, or the conductor layer, and provided the said resin composition on it.

As the surface roughening method, the electrical insulation layer which consists of electrically insulating resin is apply | coated to a conductor layer by the above-mentioned coating method, and the surface of an electrical insulation layer after heat-hardening is desired by sandblasting method, wet blasting method, brushing process, etc. May be formed.

It is preferable that the thickness of the electrical insulation layer 810 exists in the range of 10-50 micrometers from a viewpoint of multilayering of an FPC board | substrate, More preferably, it is 10-25 micrometers.

(Flexible Printed Wiring Board of Second Embodiment)

As a flexible printed wiring board of this invention, it is a flexible printed wiring board which consists of an electrical insulation layer, an adhesive bond layer, and a conductor layer at least as 2nd Embodiment, and the ten-point average roughness of the surface of the said electrical insulation layer is 1.5 micrometers or more- A flexible printed wiring board is provided, characterized in that the contact angle is less than or equal to 60 ° and less than or equal to 120 °, or that the 10-point average roughness is less than or equal to 2.0 m and less than or equal to 4.0 m.

5 is a cross-sectional view of the flexible printed wiring board of the second embodiment.

In FIG. 5, the flexible printed wiring board 900 includes a conductor layer 930, an adhesive layer 920, and an electrical insulation layer 910.

The electrical insulation layer 910 of 2nd Embodiment consists of an electrical insulation film, The surface of the electrical insulation layer 910 has a 10-point average roughness of 1.5 micrometers or more and less than 2.0 micrometers, and the contact angle is 60 degrees or more and 120 Less than or 10 point average roughness is 2.0 micrometers or more and less than 4.0 micrometers.

Thereby, when the said flexible printed wiring board is laminated | stacked in multiple numbers, the said electrically insulating layer which opposes by using the flexible printed wiring board of the said structure even if it heats pressurization of about 140-200 degreeC * 20-50 kgf / cm <2>, for example. Adhesion of the flexible printed wiring board is maintained, and the flex resistance is improved.

As a method of making the surface of the electrical insulation layer 910 have a ten-point average roughness of 1.5 µm or more and less than 2.0 µm and a contact angle of 60 ° or more and less than 120 °, the surface of the electrical insulation film may be, for example, a hydroxyl group or a carboxyl group. There is a method of not introducing a hydrophilic functional group. Specifically, the method of not performing surface treatment, such as a plasma treatment, a corona treatment, and a coupling treatment, is mentioned.

The surface of the electrical insulation layer 910 of 2nd Embodiment of this invention is obtained by making it unprocessed. In addition, you may perform the surface treatment for improving the adhesive force on the electrical insulation layer surface of the side which provides an adhesive bond layer.

By the way, by making the surface of the said electrically insulating film untreated, the mechanism which prevents adhesion of the surface of the opposing electrically insulating layer was estimated as follows.

Conventionally, in order to improve the adhesion between the electrical insulation layer and the adhesive layer, a surface treatment such as plasma treatment and corona treatment is performed to introduce surface functional groups (especially hydrophilic functional groups such as carboxyl groups and hydroxyl groups) into the electrical insulation layer. This is being taken. This is a method of improving adhesiveness by utilizing secondary cohesive bonds such as chemical bonds or hydrogen bonds between the surface functional groups introduced into the insulating layer and the reactive functional groups in the adhesive composition.

In the present invention, when the electrical insulation layers having the surface functional groups are pressed against each other by heating and pressurized, the layers are in close contact with each other. Therefore, it is considered that the adhesion phenomenon occurs due to secondary cohesion. It was assumed that the surface functional group needs to be subtracted as much as possible.

Moreover, as a determination method of the presence or absence of the surface functional group in this invention, when the number of surface functional groups is few, a contact angle is large, and in many cases, a contact angle tends to become small, and it judged by the contact angle.

In the present embodiment in the present invention, as described above, when the 10-point average roughness of the surface of the electrical insulation layer is 1.5 µm or more and less than 2.0 µm, the contact angle is 60 ° or more and less than 120 °. Even if the 10-point average roughness of the surface of the layer is 1.5 µm or more and less than 2.0 µm, when the contact angle is less than 60 °, the surface of each layer is in close contact when heated and pressed in an opposing form.

In addition, the surface of the electrical insulation layer 910 is set so that the ten point average roughness of the surface is set to 2.0 µm or more and less than 4.0 µm using a surface roughening method such as sandblasting, wet blasting, and brushing. Also good.

In addition, when the contact angle is less than 60 ° when the surface roughness is 2.0 µm or more and less than 4.0 µm, the contact area decreases due to the unevenness, so the influence of the surface functional group is small. Therefore, close contact does not occur.

The adhesive layer 920 is not particularly limited as long as it is an adhesive used in the field of flexible printed wiring, and an adhesive or the like based on an epoxy resin is employed.

It is preferable that the thickness of the adhesive bond layer 920 exists in the range of 5-50 micrometers from a viewpoint of multilayering of an FPC board | substrate, More preferably, it is 10-25 micrometers.

As the electrical insulation layer 910, electrical insulation films, such as a polyimide film, a polyamide film, a polyamideimide film, and a polyether ether ketone film, are employ | adopted, for example. Moreover, the polyimide which has sufficient heat resistance and flexibility is preferable. The thickness of the electrical insulation layer is not particularly specified and is appropriately selected by the design of the desired multilayer FPC substrate.

As the conductor layer 930, metal foil, such as copper, silver, aluminum, etc. are used, for example. The thickness of the metal foil is not particularly specified and is appropriately selected by the design of the desired multilayer FPC substrate.

In the formation method of the flexible printed wiring board 900 of this embodiment, an adhesive is appropriately apply | coated to the surface of a conductor layer or an electrical insulation layer, and a flexible printed wiring board is formed by providing an electrical insulation layer or a conductor layer.

As a coating method, a comma coater, a die coater, a gravure coater, etc. can be suitably employ | adopted according to application | coating thickness.

(Flexible Printed Wiring Board of Third Embodiment)

As a flexible printed wiring board of this invention, as a 3rd embodiment, the coverlay which consists of an adhesive bond layer and an electrical insulation layer is a flexible printed wiring board provided in the conductor layer, and it is ten points of the surface of the electrical insulation layer in the said coverlay. A flexible printed wiring board is provided, wherein the average roughness is 1.5 µm or more and less than 20 µm, and the contact angle is 60 ° or more and less than 120 °, or the 10-point average roughness is 2.0 µm or more and less than 4.0 µm.

6 is a cross-sectional view of the flexible printed wiring board of the third embodiment.

In FIG. 6, the coverlay 700 which consists of the electrical insulation layer 710 and the adhesive bond layer 720 is a conductor layer in which the circuit pattern, such as the flexible printed wiring board of 1st Embodiment or 2nd Embodiment, is formed. It is provided on the phase.

According to the third aspect of the present invention, there is provided a flexible printed wiring board in which a coverlay composed of an adhesive layer and an electrical insulation layer is provided on a conductor layer, and the ten-point average roughness of the surface of the electrical insulation layer is 1.5 µm or more and less than 2.0 µm. And a contact angle is 60 degrees or more and less than 120 degrees, or 10 point average roughness is 2.0 micrometers or more and less than 4.0 micrometers.

Thereby, when the said various flexible printed wiring boards are laminated | stacked, for example, even if heat pressurization of about 140-200 degreeC * 20-50 kgf / cm <2> uses the flexible printed wiring board of the said structure, the said electrically opposed electricity Since adhesion of the insulating layer is prevented, the flexibility of each flexible printed wiring board is maintained, and the flex resistance is improved.

The surface of the electrical insulation layer 710 has a 10-point average roughness of 1.5 µm or more and less than 2.0 µm, and a contact angle of 60 ° or more and less than 120 °, or a 10-point average roughness of 2.0 µm or more and less than 4.0 µm. It is preferable to set it as the method as described in 2nd Embodiment, and it is obtained by making the surface of the said insulating layer 710 untreated. In addition, you may perform the surface treatment for improving the adhesive force on the electrical insulation layer surface of the side which provides an adhesive bond layer.

The formation method of the coverlay 700 is obtained by apply | coating an adhesive agent on the surface of an electrical insulation layer suitably, and heating and drying to make it the semi-hardened state (henceforth B stage). 3rd Embodiment A flexible printed wiring board is formed by providing the said coverlay on the conductor layer from which the circuit pattern was obtained, and heat-hardening.

As a coating method, a comma coater, a die coater, a gravure coater, etc. can be suitably employ | adopted according to application | coating thickness.

The adhesive layer 720 is not particularly limited as long as it is an adhesive used in the field of flexible printed wiring, and an adhesive or the like based on an epoxy resin is employed.

It is preferable that the thickness of the adhesive bond layer 720 exists in the range of 5-50 micrometers from a viewpoint of multilayering of an FPC board | substrate, More preferably, it is 10-25 micrometers.

As the electrical insulation layer 710, electrical insulation films, such as a polyimide film, a polyamide film, a polyamideimide film, and a polyether ether ketone film, are employ | adopted, for example. Moreover, the polyimide which has sufficient heat resistance and flexibility is preferable. The thickness of the electrical insulation layer is not particularly specified and is appropriately selected by the design of the desired multilayer FPC substrate.

(Flexible printed wiring board of the fourth embodiment)

As a flexible printed wiring board of this invention, it is a multilayer flexible printed wiring board in which at least 2 flexible printed wiring boards, such as 3rd embodiment, were laminated | stacked as 4th Embodiment, and 2 or more flexible which was bent and exposed. The surface of the electrically insulating layer of a flexible printed wiring board is opposed, it is non-adhesive, and a part of said flexible printed wiring board is laminated | stacked on the 1st multilayer flexible printed wiring board and the 2nd multilayer flexible printed wiring board, respectively. Flexible printed wiring boards are provided.

7 is a cross-sectional view of the multilayer flexible printed wiring board of the fourth embodiment. In addition, the same structure is attached | subjected with the same number and is demonstrated below.

In Fig. 7, the multilayer flexible printed wiring board 600 is composed of a first multilayer flexible printed wiring board 610, a second multilayer flexible printed wiring board 620, and a flexible printed wiring board 630.

In addition to the multilayer flexible printed wiring boards 610 and 620, the multilayer flexible printed wiring board 600 may provide another multilayer flexible printed wiring board through the flexible printed wiring board 630 as needed.

The said 1st, 2nd multilayer flexible printed wiring board 610, 620 is the adhesive sheet of the preliminary impregnation thing or resin sheet which impregnated the glass fiber with the adhesive agent in the semi-cured state about the flexible printed wiring board of embodiment mentioned above. Through 60 and the like, it is possible to laminate a plurality of flexible printed wiring boards in various patterns.

In the flexible printed wiring board 630, both surfaces of the flexible printed wiring board of the above-described embodiment are electrically insulating layers and are exposed in a bendable state, and a part of the flexible printed wiring board is the multilayer flexible print. The wiring boards 610 and 620 are stacked. In addition, the electrical insulation layers of the two or more flexible printed wiring boards 630 oppose each other, and are located in a non-adhesive state.

According to the 4th aspect of this invention, it is a multilayer flexible printed wiring board in which at least 2 flexible printed wiring boards, such as 3rd Embodiment, were laminated | stacked, and are electric in the state which can be bent, and exposed two or more flexible printed wiring boards. The surface of an insulating layer faces and is non-adhesive, and a part of said flexible printed wiring board is laminated | stacked on the 1st multilayer flexible printed wiring board and the 2nd multilayer flexible printed wiring board, respectively.

Thereby, even if it heat-presses about 140-200 degreeC * 20-50kgf / cm <2>, for example, since the adhesion | attachment of several flexible flexible printed wiring boards is prevented, the flexibility of each flexible printed wiring board is maintained, Flex resistance is improved.

(Flexible Printed Wiring Board of Fifth Embodiment)

As a flexible printed wiring board of this invention, in the mobile telephone terminal which has the hinge part which rotatably connects a 1st housing and a 2nd housing as 5th Embodiment, it is exposed in the bendable state which passes through the said hinge part, and is exposed. Provided is a mobile phone terminal using a multilayer flexible printed wiring board having the flexible printed wiring board in which the electrically insulating layer surfaces of two or more flexible printed wiring boards face each other and are in a non-adhesive state.

Fig. 8 shows a structural diagram of a multilayer flexible printed wiring board passing through the hinge portion of the mobile telephone terminal as the fifth embodiment. In addition, about the same structure, the same number is attached | subjected and it demonstrates below.

In FIG. 8A, the flexible printed wiring board 630 passing through the hinge portion 20 is wound once in a spiral shape.

In FIG. 8B, the flexible printed wiring board 630 passing through the hinge portion 20 is wound in a U shape.

According to a fifth aspect of the present invention, in a mobile phone terminal having a hinge portion for rotatably connecting a first housing and a second housing, the two or more flexible printed wiring boards that are bent and exposed are electrically If the surface of the insulating layer is opposed and the multilayer flexible printed wiring board having the flexible printed wiring board in the non-adhesive state is in a state passing through the hinge portion as shown in Fig. 8, the opening and closing of the first housing and the second housing may be repeated. Since the flexibility of the said flexible printed wiring board is maintained, it has sufficient flex resistance.

Hereinafter, although an Example and a test example of this invention are given and this invention is demonstrated more concretely, this invention is not restrict | limited at all by these Examples.

<1st Example-5th Example and 1st Comparative Example-3rd Comparative Example>

The surface roughness, contact angle, adhesiveness, and dielectric breakdown voltage in the two-layer substrate were evaluated, and the results are shown in Table 1.

First, the blend shown in Table 1 was prepared. The detail of each component in Table 1 is as follows.

The polyimide resin generates an imide bond by heat curing the polyimide precursor resin. Representative polyimide precursor resins include polyamic acid. As the polyimide precursor resin used in Examples and Comparative Examples, a polyamine acid obtained by reacting diamines containing paraphenylene diamine or a derivative thereof with an aromatic tetracarboxylic acid was used.

Moreover, the calcium hydrogen phosphate used the thing whose peak of particle size distribution is 1-3 micrometers (average particle diameter of filler 1-3 micrometers). When mixing polyimide precursor resin and calcium hydrogen phosphate, solvent, such as N-methyl- 2-pyrrolidone, was added as needed, and it adjusted until it became the viscosity which can be apply | coated on copper foil. In addition, the weight part of polyimide resin of Table 1 shows the weight part of polyimide after hardening.

Production of two-layer board (laminate board with one side copper)

Each resin composition of the composition shown in Table 1 was apply | coated so that the thickness might become 25 micrometers after hardening using the bar coater on the roughening surface of the rolled copper foil (made by Nikko Materials, BHY, 18 micrometers).

The solvent is removed by raising the temperature stepwise in a temperature range of 80 ° C to 150 ° C for 10 minutes.

Subsequently, curing is performed by raising the temperature stepwise in a temperature range of 180 ° C to 400 ° C for 3 hours under a nitrogen atmosphere.

Fabrication of coverlay

A resin composition mainly composed of an epoxy resin (for coverlays), which is usually used in fields such as a flexible printed wiring board (for example, the resin composition described in JP 2001-15876 A, etc. can be used). The thickness after drying using a bar coater on the opposite side of the process surface of the polyimide film (made by Kaneka Co., Ltd., Apical 12.5 micrometers NPI) to which one surface was given the predetermined process (sandblasting process) Was applied so that 25 was set to 25 m.

After heat-drying at 150 degreeC for 5 minutes, and performing B stage formation, the separate film (Lintec Co., Ltd. product, mold release PET film, 38 micrometers) was bonded by the laminator to the resin composition surface.

In addition, a separate film peels and uses at the time of use.

Fabrication of Flexible Printed Wiring Boards

The coverlay adhesive surface which peeled a separator film was bonded together on the 2-layer board | substrate which formed the circuit, or the 3-layer board | substrate, and it press-presses on 180 degreeCx20 kgf / cm <2> * 60 minutes conditions, and obtains a flexible printed wiring board.

<10 point average roughness>

Measuring apparatus: It calculated by the following measuring method using the laser microscope (the Olympus make, LEXT OLS300).

(1) The measurement surface is mounted on the stage (in this embodiment, the polyimide surface was used as the measurement surface).

(2) Focus using the lens at 100x magnification.

(3) Set Top and Bottom in the Z-axis direction from the brightness of the image.

(4) A laser beam of 408 nm is irradiated to measure the reflected light, and the surface is scanned in the range of 125 µm in the X-axis direction and 96 µm in the Y-axis direction.

(5) The cutoff value is set to 1/5, and the surface roughness Rz is calculated using analysis software accompanying the measuring device.

<Surface contact angle>

Measuring apparatus: It measured by the following measuring method using the CA-X type | mold of Kyogen Corporation.

0.9 μl of pure water (droplet of 0.9 mm in diameter) is added dropwise to the measurement sample. Pure water dropped is confirmed from the cross section, and the height h and the diameter 2r of the droplet shown in FIG. 9 are measured. From h and 2r thus obtained, the contact angle θ is calculated by the following equation. 9 is a cross-sectional view of water droplets generated when pure water is added dropwise.

tanθ1 = h / r θ = 2tan ^-1 (h / r)

<Adhesiveness>

In the two-layer board | substrate, two laminated sheets with copper were laminated | stacked in the state shown in FIG. The adhesion test was performed by opposing the polyimide surfaces of the two-layer copper-clad laminate of the same resin composition for each example. In addition, adhesion confirmation was performed visually and it evaluated based on the following criteria. (Circle): It does not adhere, x: It adhered.

Insulation breakdown voltage

Using HVT-200-5 manufactured by Yamahi Denji Corporation as the measuring device, the electrode was set to 25 mm Ø, and the pressure was increased to 500 V / sec by No. 2 insulating oil specified in JIS C 2320 (electric insulating oil). The value was determined when the dielectric breakdown occurred. The sample piece used what removed the conductor layer of the board | substrate by the etching method etc., and cut into 100 mm square. Based on the measurement result, it evaluated by the following reference | standard.

(Circle): It has 200 V / micrometer or more and the outstanding dielectric breakdown voltage.

(Triangle | delta): It has the dielectric breakdown voltage of the level more than 100-200 V / micrometer, and there is no problem practically.

TABLE 1

First embodiment Comparative Example 1 Second embodiment Third embodiment Fourth embodiment Fifth Embodiment 2nd comparative example Third Comparative Example Polyimide Resin * 1 100 100 100 100 100 100 100 100 Calcium Hydrogen Phosphate 0.2 0.2 3 3 10 10 0 20 Corona treatment Untreated process Untreated process Untreated process Untreated Untreated 10 point average roughness 1.9 1.9 2.5 2.5 3.6 3.6 One 4.4 Surface contact angle 65 ° 55 ° 65 ° 55 ° 65 ° 55 ° 65 ° 65 ° Adhesion ○ × ○ ○ ○ ○ × ○ Dielectric breakdown voltage ○ ○ ○ ○ ○ ○ ○ △

* 1 polyimide resin: The polyamic acid was 100 weight part of polyimide resins after heat-hardening.

The unit of composition (polyimide resin and calcium hydrogen phosphate) is parts by weight.

The unit of ten-point average roughness is micrometer.

<Sixth to Eighth Examples and Fourth Comparative Example>

The surface treatment state and adhesiveness of the polyimide film in a three-layered board | substrate are evaluated, and the result is shown in Table 2. In addition, the measurement and evaluation method which are not specifically mentioned are the same as the above.

Production of three-layer board (laminate board with one side copper)

A resin composition (for example, a resin composition described in JP-A-2001-15876, etc. can be used) mainly composed of epoxy resins (for substrates), which is usually used in the fields of flexible printed wiring boards and the like. After curing using a bar coater on the opposite side of the treated surface of the polyimide film (manufactured by Kaneka Co., Ltd., Apical 12.5 μm NPI) subjected to a predetermined treatment (sandblast treatment) on one side, the thickness Was applied such that

After heat-drying at 150 degreeC for 5 minutes and performing B stage formation, the roughening surface of the rolled copper foil (made by Nikko Material Co., Ltd., BHY, 18 micrometers) is bonded by the laminator to the resin composition surface.

<Adhesiveness>

The temperature is gradually raised in a temperature range of 40 ° C. to 200 ° C. for 3 hours, and the resin composition is completely cured to obtain a single-sided copper clad laminate.

In the three-layered substrate, a copper-clad laminate was produced using polyimide having respective characteristics, two sheets were laminated in the state shown in Fig. 11, and the press treatment was performed at 180 ° C. × 20 kgf / cm 2 × 60 minutes. Confirmed. The adhesion test was performed by opposing the polyimide surfaces of the three-layer copper clad laminate produced from each film. In addition, confirmation of adhesion was visually confirmed and evaluated based on the following criteria. (Circle): It does not adhere, x: It adhered.

TABLE 2

Film surface properties Sixth embodiment Seventh embodiment Fourth Comparative Example Eighth embodiment 10-point average roughness (Rz) 1.9 1.9 1.9 3.6 Surface contact angle 65 ° 10 ° * 2 55 ° * 3 65 ° * 4 Adhesion ○ ○ × ○

The unit of ten-point average roughness is micrometer.

The details of the * mark in Table 2 are as follows.

※ 2 ; A polyimide film CF _{4 (4} fluorocarbon) or C ₂ F ₆ (perfluoroalkyl ethane) to the plasma treatment in a nitrogen atmosphere was added a small amount.

※ 3; With corona treatment

※4 ; Sandblasted

In addition, in the present Example, although surface treatment was performed by the sandblasting process, in this invention, it does not specifically limit to a surface treatment method. As another processing method, roughening is possible, for example by a wet blast method, a brushing process, etc.

The present invention relates to a method of stacking a substrate having a non-bonded portion and an adhesive portion, comprising: a flexible printed wiring board, a multilayer flexible printed wiring board, and a portable telephone terminal capable of preventing adhesion of the FPC substrate of the bent portion and maintaining sufficient flex resistance. Has industrial applicability.

Claims (9)

A flexible printed wiring board comprising at least an electrical insulation layer and a conductor layer, wherein the ten-point average roughness of the surface of the electrical insulation layer is 1.5 µm or more and less than 2.0 µm, and the contact angle is 60 ° or more and less than 120 °, or 10 points An average roughness is 2.0 micrometers or more and less than 4.0 micrometers, The flexible printed wiring board characterized by the above-mentioned. The flexible printed wiring board according to claim 1, wherein the electrical insulation layer is made of polyimide. A flexible printed wiring board comprising at least an electrical insulation layer, an adhesive layer, and a conductor layer, wherein the ten-point average roughness of the surface of the electrical insulation layer is 1.5 µm or more and less than 2.0 µm, and the contact angle is 60 ° or more and less than 120 °. Or 10 point average roughness is 2.0 micrometers or more and less than 4.0 micrometers, The flexible printed wiring board characterized by the above-mentioned. The flexible printed wiring board according to claim 3, wherein the electrical insulation layer is made of polyimide. The coverlay comprising the adhesive layer and the electrical insulation layer is a flexible printed wiring board provided in the conductor layer, and the ten-point average roughness of the surface of the electrical insulation layer in the coverlay is 1.5 µm or more. A flexible printed wiring board, having a contact angle of less than 2.0 µm and less than 60 µm to less than 120 µm, or a 10-point average roughness of 2.0 µm or greater and less than 4.0 µm. It is a multilayer flexible printed wiring board in which two or more flexible printed wiring boards of Claim 5 were laminated | stacked, It is the state which can be bent, and the electrical insulation layer surface of the exposed 2 or more flexible printed wiring boards is opposed, and is non-adhesive state. And a part of said flexible printed wiring board is laminated | stacked on the 1st multilayer flexible printed wiring board and the 2nd multilayer flexible printed wiring board, respectively, The multilayer flexible printed wiring board characterized by the above-mentioned. A mobile phone terminal having a hinge portion rotatably connecting a first housing and a second housing, wherein the bent portion of the multilayer flexible printed wiring board according to claim 6 passing through the hinge portion is exposed at least two flexible prints. A mobile telephone terminal using a multilayer flexible printed wiring board, wherein the surface of the electrical insulation layer of the wiring board is opposed to each other and is in a non-adhesive state. It is a laminated board with a metal used for the flexible printed wiring board of any one of Claims 1-6, or the mobile telephone terminal of Claim 7, It is equipped with the electrical insulation layer and the conductor layer before circuit formation at least, The laminated sheet with a metal characterized by the 10-point average roughness of the insulating layer surface being 1.5 micrometer or more and less than 2.0 micrometers, and having a contact angle of 60 degrees or more and less than 120 degrees, or 10-point average roughness 2.0 micrometers or more and less than 4.0 micrometers. The coverlay used for the flexible printed wiring board of Claim 5 or 6, or the mobile telephone terminal of Claim 7, It consists of an adhesive bond layer and an electrical insulation layer, and the ten-point average roughness of the surface of the said electrical insulation layer is A coverlay comprising at least 1.5 μm and less than 2.0 μm, and having a contact angle of at least 60 ° and less than 120 °, or a ten point average roughness of at least 2.0 μm and less than 4.0 μm.

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