JP5082296B2 - Adhesive with wiring and circuit connection structure - Google Patents

Description

  The present invention relates to an adhesive with wiring.

  Circuit boards such as integrated circuits are produced by forming a metal foil layer such as copper or aluminum on a base material and forming wiring on the base material by etching or plating. As the substrate, a hard substrate such as ceramic or glass-epoxy, or a film-like substrate such as polyimide film or PET film is used. Since this circuit board itself does not have adhesiveness, solder and anisotropic conductive adhesive are used for mechanical connection and electrical connection between the circuit boards.

  In recent years, the density of circuits has been increasing in the field of precision electronic equipment, and the wiring width and the wiring interval have become extremely narrow, so that the wiring is easily dropped, peeled off, or misaligned. In order to solve this problem, adhesives for circuit connection for electric and electronic use that have excellent low-temperature fast curing properties and have a sufficiently long pot life have been developed (for example, see Patent Documents 1 and 2).

Conventionally, this circuit connecting adhesive has been widely used when a flexible printed circuit (hereinafter referred to as FPC) is mounted on a liquid crystal display panel in a manufacturing process of a liquid crystal display device or the like. When mounting using such a conventional adhesive for circuit connection,
(1) Prepare a circuit board having a connection terminal formed of indium tin oxide (hereinafter referred to as ITO) on a glass or a metal terminal formed on a glass-epoxy substrate.
(2) Temporarily press-bonding an adhesive for circuit connection onto the circuit board,
(3) peeling the base material (separator) of the adhesive for circuit connection,
(4) The FPC is placed on the circuit board and aligned (aligned).
(5) Final crimping (connection)
I went through the process.

In addition, for the purpose of preventing FPC oxidation and reducing costs, a technique in which an adhesive for circuit connection (anisotropic conductive film) is previously formed on the FPC has also been proposed (see, for example, Patent Document 3).
International Publication No. 98/44067 Pamphlet International Publication No. 01/015505 pamphlet JP 2005-285640 A

  Such a conventional technique requires many steps as described above, and therefore has a long manufacturing time, which causes an increase in cost. In addition, three members, that is, an adhesive for circuit connection, a circuit board, and an FPC, are necessary, which is a major factor in increasing the cost.

  As described above, the present inventors have fewer steps and member points required for circuit connection than the conventional method of connecting circuit boards with solder or adhesive, and can obtain a good connection resistance. Circuit connection members and circuit connection methods were searched.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide an adhesive with wiring that can reduce the number of steps and the number of members necessary for circuit connection and can obtain good connection resistance.

  In order to solve the above-mentioned problem, the adhesive with wiring of the present invention includes a film adhesive and a wiring provided on the main surface of the film adhesive.

  When the adhesive with wiring of the present invention is pressed against the circuit board, the film adhesive adheres to the circuit board, whereby the wiring of the adhesive with wiring is connected to the circuit board. Therefore, by using the adhesive with wiring of the present invention, it is not necessary to separately use solder or an adhesive when circuit connection is performed. Therefore, the number of processes and the number of members necessary for circuit connection can be reduced. Furthermore, favorable connection resistance can be obtained by using the adhesive with wiring of the present invention.

  The film adhesive preferably contains conductive particles. Thereby, when connecting the adhesive with wiring to the circuit board, the connection resistance between the wiring of the adhesive with wiring and the circuit board can be reduced.

  Moreover, it is preferable that the said adhesive with a wiring is further equipped with the base material provided on the surface on the opposite side to the said main surface of the said film adhesive. Thereby, when winding adhesive agent with wiring in roll shape, adhesion | attachment of film adhesives can be suppressed. Moreover, since a base material supports a film adhesive, when forming wiring on the main surface of a film adhesive, handling of a film adhesive becomes easy. Furthermore, it can suppress that the surface on the opposite side to the main surface of a film adhesive adheres to another member, an apparatus, etc.

  Moreover, it is preferable that the said adhesive agent with a wiring is further equipped with another film adhesive provided so that the said wiring might be covered on the said main surface of the said film adhesive. In this case, when the adhesive with wiring is used as a circuit board, the adhesion between the adhesive with wiring and the circuit board can be improved.

  Furthermore, the another film adhesive preferably contains conductive particles. Thereby, when connecting the adhesive with wiring to the circuit board, the connection resistance between the wiring of the adhesive with wiring and the circuit board can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive agent with a wiring which can obtain the favorable connection resistance with few process steps and number of members required for circuit connection is provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

(First embodiment)
FIG. 1 is a perspective view schematically showing an adhesive with wiring according to the first embodiment. An adhesive with wiring 20 shown in FIG. 1 (hereinafter referred to as “adhesive 20”) includes a film adhesive 1 and a wiring 2 provided on a main surface 21 of the film adhesive 1. The adhesive 20 is connected to a circuit board 30 described later. A plurality of wirings 2 are provided at predetermined intervals along the surface direction of the main surface 21.

  FIG. 2 is a perspective view schematically showing each step of the method for manufacturing the circuit connection structure obtained by connecting the adhesive with wiring according to the first embodiment to the circuit board.

  First, a film adhesive 1 is prepared as shown in FIG. The film adhesive 1 is obtained, for example, by applying a solution containing an adhesive composition on a film substrate and drying the applied solution.

  Subsequently, as shown in FIG. 2B, the wiring 2 is formed on the main surface 21 of the film adhesive 1 to obtain the adhesive 20. The wiring 2 is preferably formed by forming a metal foil on the main surface 21 of the film adhesive 1 by laminating or the like and then etching the metal foil. In this case, the high-definition wiring 2 can be formed. Alternatively, the wiring 2 may be formed by directly pressing a metal wire against the main surface 21 of the film adhesive 1. In this case, since the number of steps is small, the wiring 2 can be formed in a short time.

  On the other hand, a circuit board 30 having a substrate 3 and wirings 12 provided on the substrate 3 is prepared. The substrate 3 may be a hard base made of glass, ceramic, glass-epoxy, or the like, or may be a polyimide film or a PET film, for example. The wiring 12 is made of the same material as that of the wiring 2, for example. The adhesive 20 is aligned with the circuit board 30 as shown in FIG. As a result, the wiring 2 is disposed opposite to the wiring 12.

  Next, the adhesive 20 is connected to the circuit board 30 by pressing the adhesive 20 against the circuit board 30, and the circuit connection structure 40 is produced as shown in FIG. At this time, for example, the film adhesive 1 is cured by heating and pressurizing the adhesive 20 and the circuit board 20. Thereby, the hardened | cured material 8 of the film adhesive 1 is obtained. The cured product 8 connects the wiring 2 and the wiring 12 electrically and mechanically. Further, the adjacent wirings 2 are insulated by the cured product 8.

  As described above, when the adhesive 20 of this embodiment is pressed against the circuit board 30, the film adhesive 1 adheres to the circuit board 30, whereby the wiring 2 is connected to the wiring 12. Therefore, the use of the adhesive 20 eliminates the need to separately use solder or an adhesive when performing circuit connection. Therefore, the number of members used for circuit connection can be reduced, and the number of circuit connection steps can be reduced. Therefore, the production efficiency of the circuit connection structure 40 can be improved and the production cost can be reduced. Furthermore, by using the adhesive 20, a good connection resistance can be obtained.

  It is preferable that the film adhesive 1 contains a photocurable adhesive or a thermosetting adhesive. In this case, when the adhesive 20 is connected to the circuit board 30, the film adhesive 1 can be chemically reacted and cured. Moreover, since the heat resistance and moisture resistance of the cured product 8 are dramatically improved, the reliability of electrical and mechanical connection between the wiring 2 and the wiring 12 is improved. Examples of the material for the film adhesive 1 include II. Of the Adhesion Handbook (2nd edition, published by Nikkan Kogyo Shimbun, edited by Japan Adhesion Association). Adhesives described in the adhesive section are listed.

  As a material of the wiring 2, for example, a metal excellent in stretchability such as copper, silver, and gold is preferable. In this case, since the width and diameter of the wiring 2 can be reduced, the high-density wiring 2 can be formed. Moreover, it is preferable that the surface layer of the wiring 2 contains gold. Thereby, the connection resistance between the wiring 2 and the wiring 12 can be lowered.

(Second Embodiment)
FIG. 3 is a perspective view schematically showing an adhesive with wiring according to the second embodiment. An adhesive with wiring 20a shown in FIG. 3 (hereinafter referred to as “adhesive 20a”) is electrically conductive in the film adhesive 1 instead of the film adhesive 1 of the adhesive 20 according to the first embodiment. A film adhesive 1a containing particles P is provided. The film adhesive 1a is, for example, an anisotropic conductive adhesive. The adhesive 20 a is connected to the above-described circuit board 30 in the same manner as the adhesive 20.

  In the adhesive 20a, the wiring 2 can be connected to the wiring 12 more stably when the adhesive 20a is connected to the circuit board 30 than when the adhesive 20 is connected to the circuit board 30. The connection resistance with the wiring 12 can be reduced.

  Examples of the conductive particles P include particles made of metal such as Au, Ag, Ni, Cu, and solder, carbon, and the like. The conductive particles P may be those in which the surfaces of particles made of a transition metal such as Ni are coated with a layer made of a noble metal such as Au. In addition, the conductive particles P may be those in which the surface of particles made of non-conductive glass, ceramic, plastic, etc. is coated with a conductive layer, and the conductive layer is coated with an outermost layer made of noble metals, Particles may be used. In this case, since the conductive particles P are deformable by heating and pressurization, the contact area between the conductive particles P and the wirings 2 and 12 increases at the time of circuit connection, which is preferable because the reliability is improved. The thickness of the noble metal layer is preferably 100 angstroms (10 nm) or more in order to obtain good connection resistance. Content of the electroconductive particle P can be made into the range of 0.1-30 volume parts with respect to 100 volume parts of resin components of the film adhesive 1 according to a use. In order to prevent a short circuit between adjacent wires due to excessive conductive particles P, the content of the conductive particles P is preferably 0.1 to 10 parts by volume.

(Third embodiment)
FIG. 4 is a perspective view schematically showing an adhesive with wiring according to the third embodiment. An adhesive with wiring 20b shown in FIG. 4 (hereinafter referred to as “adhesive 20b”) further includes a base material (also referred to as a separator) 4 in addition to the configuration of the adhesive 20 according to the first embodiment. . The substrate 4 is provided on a surface 22 opposite to the main surface 21 of the film adhesive 1. The adhesive 20 b is connected to the circuit board 30 described above, similarly to the adhesive 20.

  For example, the adhesive 20b is formed by first applying a solution containing the adhesive composition on the substrate 4 and drying the applied solution to form the film-like adhesive 1, and then forming the main adhesive of the film-like adhesive 1. It is obtained by forming the wiring 2 on the surface 21.

  In the adhesive 20b, adhesion between the film adhesives 1 can be suppressed when the adhesive 20b is wound into a roll. Moreover, since the base material 4 supports the film adhesive 1, when forming the wiring 2 on the main surface 21 of the film adhesive 1, handling of the film adhesive 1 becomes easy. Furthermore, even if the surface 22 of the film adhesive 1 comes into contact with a press machine or the like that performs heating and pressurization, the adhesive can be prevented from being transferred to the press machine or the like.

(Fourth embodiment)
FIG. 5 is a perspective view schematically showing an adhesive with wiring according to the fourth embodiment. The adhesive with wiring 20c shown in FIG. 5 (hereinafter referred to as “adhesive 20c”) further includes another film adhesive 5 in addition to the configuration of the adhesive 20b according to the third embodiment. The film adhesive 5 is provided on the main surface 21 of the film adhesive 1 so as to cover the wiring 2. The adhesive 20 c is connected to the above-described circuit board 30 in the same manner as the adhesive 20.

  The adhesive 20c is obtained by, for example, bonding the film adhesive 1 and the film adhesive 5 by pressing the film adhesive 5 on the wiring 2 of the adhesive 20b.

  In the adhesive 20 c, the film adhesive 5 adheres to the circuit board 30 when the adhesive 20 c is connected to the circuit board 30. Therefore, since the adhesive 20c and the circuit board 30 are connected without a gap, the adhesiveness between the adhesive 20c and the circuit board 30 can be improved as compared with the case where the adhesive 20b is used. As a result, the electrical and mechanical connection reliability between the wiring 2 and the wiring 12 is improved.

  The film adhesive 5 is preferably made of the same material as the film adhesive 1. In this case, the film adhesives 1 and 5 are firmly bonded.

(Fifth embodiment)
FIG. 6 is a perspective view schematically showing an adhesive with wiring according to the fifth embodiment. An adhesive with wiring 20d shown in FIG. 6 (hereinafter referred to as “adhesive 20d”) is conductive in the film adhesive 5 instead of the film adhesive 5 of the adhesive 20c according to the fourth embodiment. A film adhesive 5a containing particles P is provided. The film adhesive 5a is, for example, an anisotropic conductive adhesive. The adhesive 20 d is connected to the above-described circuit board 30 in the same manner as the adhesive 20.

  In the adhesive 20d, the wiring 2 can be connected to the wiring 12 more stably when the adhesive 20d is connected to the circuit board 30 than when the adhesive 20c is connected to the circuit board 30. The connection resistance with the wiring 12 can be reduced.

  In the adhesive 20d, the film adhesive 1a may be used instead of the film adhesive 1, but as shown in FIG. 6, the combination of the film adhesive 1 and the film adhesive 5a is different. Particularly preferred. In this case, the insulation between the adjacent wirings can be maintained well, and the connection resistance between the opposing wirings can be reduced.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
A polyester sheet having a thickness of 50 μm (manufactured by Toyobo Co., Ltd., Byron 500 (product name)) was prepared as a film adhesive. Subsequently, ten gold wires having a length of 10 cm and a diameter of 0.1 mm were formed at a pitch of 200 μm on the surface of the polyester sheet using a wiring machine. Thus, the adhesive with a wiring of Example 1 was obtained (refer FIG. 1).

(Example 2)
50 g of a solid epoxy resin (Japan Epoxy Resin Co., Ltd., Epicoat # 1007 (product name)) in toluene (boiling point 110.6 ° C., SP value 8.90) / ethyl acetate (boiling point 77.1 ° C., SP Value 9.10) = dissolved in a 50/50 mixed solvent to obtain a 40% solids solution. Subsequently, a solid epoxy resin 50 g, a bisphenol A type liquid epoxy resin 45 g, and 5 g of imidazole as a curing accelerator were blended to obtain a coating solution. This coating solution was applied to a PET film having a thickness of 80 μm, one side of which was surface-treated, using a coating apparatus, and dried with hot air at 70 ° C. for 10 minutes. Thereby, a film adhesive having a thickness of 50 μm was formed on the PET film. Furthermore, the adhesive with a wiring of Example 2 was obtained by forming a gold wire on this film adhesive similarly to Example 1 (refer FIG. 4).

(Example 3)
Similarly to Example 2, a film adhesive having a thickness of 50 μm was formed on a PET film to obtain a laminate. After laminating this laminate on the main surface of the adhesive with wiring of Example 2 (surface on which the gold wire was exposed), the PET film of the laminate was peeled off, whereby the adhesive with wiring of Example 3 was used. Was obtained (see FIG. 5).

Example 4
The wiring of Example 4 was the same as Example 1 except that an anisotropic conductive film (manufactured by Hitachi Chemical Co., Ltd., AC-7073Z (product name)) having a thickness of 50 μm was used as the film adhesive. A sticky adhesive was obtained (see FIG. 3).

(Example 5)
The adhesive with wiring of Example 5 was obtained in the same manner as in Example 3 except that the laminate was formed by forming the anisotropic conductive film of Example 4 on a PET film (see FIG. 6). .

(Example 6)
An adhesive with wiring of Example 6 was obtained in the same manner as in Example 2 except that a copper wire having a length of 10 cm and a diameter of 0.1 mm was used instead of the gold wire having a length of 10 cm and a diameter of 0.1 mm. .

(Example 7)
An adhesive with wiring of Example 7 was obtained in the same manner as Example 2 except that a platinum wire having a length of 10 cm and a diameter of 0.1 mm was used instead of the gold wire having a length of 10 cm and a diameter of 0.1 mm. .

(Example 8)
An adhesive with wiring of Example 8 was obtained in the same manner as Example 4 except that a copper wire having a length of 10 cm and a diameter of 0.1 mm was used instead of the gold wire having a length of 10 cm and a diameter of 0.1 mm. .

Example 9
An adhesive with wiring of Example 9 was obtained in the same manner as in Example 4 except that a platinum wire having a length of 10 cm and a diameter of 0.1 mm was used instead of the gold wire having a length of 10 cm and a diameter of 0.1 mm. .

(Circuit connection)
Using the adhesive with wiring of Examples 1 to 9, circuit connection was performed as follows. FIG. 7 is a perspective view schematically showing a characteristic evaluation board (also referred to as a circuit board) for evaluating the characteristics of the circuit connection structure. In the characteristic evaluation substrate 50 shown in FIG. 7, a wiring 6 having a length of 2 cm and a width of 1 cm is formed on one end of the glass-epoxy substrate 9. On the other end of the glass-epoxy substrate 9, ten wires (also referred to as connection terminals) 7 having a length of 2 cm are formed at a pitch of 200 μm. Between the wiring 6 and the wiring 7, the area | region which the surface of the glass-epoxy board | substrate 9 is exposed is formed over 8 cm in length without the wirings 6 and 7 being formed.

  FIG. 8 is a perspective view schematically showing a circuit connection structure obtained by connecting the adhesive with wiring of FIG. 4 to the characteristic evaluation substrate of FIG. FIG. 8 shows a circuit connection structure in the second embodiment. In the circuit connection structure 60 shown in FIG. 8, the wiring 2 of the adhesive 20 b is connected to the wirings 6 and 7. The characteristic evaluation substrate 50 and the adhesive 20b are aligned so that one end of the wiring 2 and the wiring 6 are connected over a width of 1 cm, and the other end of the wiring 2 and the wiring 7 are connected over a width of 1 cm. . At this time, the adhesive 20b was connected to the characteristic evaluation substrate 50 by heating and pressing at 180 ° C. and 3 MPa for 20 seconds. In addition, about Example 1, 3-9, it carried out similarly to Example 2, and obtained the circuit connection structure.

(Comparative Example 1)
An anisotropic conductive film (manufactured by Hitachi Chemical Co., Ltd., AC-7073Z (product name)) having a thickness of 50 μm was transferred onto the characteristic evaluation substrate 50. Subsequently, a polyimide film was produced, and 10 gold wires having a length of 10 cm were formed on the surface of the polyimide film at a pitch of 200 μm to obtain FPC (Flexible Printed Circuits). This FPC was connected to the substrate for characteristic evaluation 50 through an anisotropic conductive film. At this time, the FPC was connected to the characteristic evaluation substrate 50 by heating and pressurizing at 180 ° C. and 3 MPa for 20 seconds.

(Comparative Example 2)
An adhesive sheet on which no wiring was formed was obtained in the same manner as in Example 2 except that no gold wire was formed. Subsequently, this adhesive sheet was connected to the characteristic evaluation substrate 50.

(Measurement of connection resistance)
For Examples 1 to 9 and Comparative Examples 1 and 2, the resistance value between adjacent wirings 7 was held immediately after circuit connection (initial) and in a high-temperature and high-humidity tank at 85 ° C. and 85% RH for 500 hours. It was measured with a multimeter (after high temperature and high humidity treatment). The resistance value is shown as an average (x + 3σ) of nine resistances between adjacent wirings 7. The obtained results are shown in Table 1. Table 1 shows the number of steps for circuit connection and the number of members used for circuit connection for Examples 1 to 9 and Comparative Example 1.

  Since the film adhesive used in Example 1 consists of a thermoplastic adhesive, and the film adhesive used in Examples 2-9 consists of a thermosetting adhesive, the connection resistance of Examples 2-9 is It is the same as or lower than the connection resistance of the first embodiment. In Example 1, disconnection of the circuit did not occur. Since the film-like adhesives used in Examples 4, 5, 8, and 9 contained conductive particles, the connection resistance after high-temperature and high-humidity treatment was particularly low.

In Examples 1, 4, 8, and 9, the number of circuit connection steps is
(1) Prepare a characteristic evaluation substrate 50;
(2) The wiring 7 of the characteristic evaluation substrate 50 and the wiring 2 of the adhesive 20b are aligned.
(3) Crimping the characteristic evaluation substrate 50 and the adhesive 20b;
It was three steps.

In Examples 2, 3, 5-7, the number of circuit connection steps is
(1) Prepare a characteristic evaluation substrate 50;
(2) The wiring 7 of the characteristic evaluation substrate 50 and the wiring 2 of the adhesive 20b are aligned.
(3) Crimping the characteristic evaluation substrate 50 and the adhesive 20b;
(4) The base material 4 of the adhesive 20b is peeled off.
4 steps.

In Comparative Example 1, the number of circuit connection steps is
(1) Prepare a characteristic evaluation substrate 50;
(2) Temporarily press-bonding an anisotropic conductive film on the substrate for characteristic evaluation 50;
(3) peeling the base material (separator) of the anisotropic conductive film;
(4) The wiring 7 of the characteristic evaluation substrate 50 and the FPC terminal are aligned.
(5) Full pressure bonding (connecting) the characteristic evaluation substrate 50 and the FPC.
5 steps.

  Moreover, in Examples 1-9, circuit connection was performed using two points of the adhesive with wiring and the board | substrate 50 for characteristic evaluation as a member. On the other hand, in Comparative Example 1, circuit connection was performed using the three points of FPC, anisotropic conductive film, and characteristic evaluation substrate 50 as members. In Comparative Example 2, circuit connection could not be performed.

It is a perspective view which shows typically the adhesive agent with a wiring which concerns on 1st Embodiment. It is a perspective view which shows typically each process of the manufacturing method of the circuit connection structure obtained by connecting the adhesive agent with wiring which concerns on 1st Embodiment to a circuit board. It is a perspective view which shows typically the adhesive agent with a wiring which concerns on 2nd Embodiment. It is a perspective view which shows typically the adhesive agent with a wiring which concerns on 3rd Embodiment. It is a perspective view which shows typically the adhesive agent with a wiring which concerns on 4th Embodiment. It is a perspective view which shows typically the adhesive agent with a wiring which concerns on 5th Embodiment. It is a perspective view which shows typically the board | substrate for characteristic evaluation for evaluating the characteristic of a circuit connection structure. It is a perspective view which shows typically the circuit connection structure obtained by connecting the adhesive agent with a wiring of FIG. 4 to the board | substrate for characteristic evaluation of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a ... Film adhesive, 2 ... Wiring, 4 ... Base material, 5, 5a ... Another film adhesive, 20, 20a, 20b, 20c, 20d ... Adhesive with wiring, 21 ... Film adhesive , 22 ... surface opposite to the main surface of the film adhesive, P ... conductive particles.

Claims (5)

And the non-Irumu-like adhesive,
Wiring provided on the main surface of the film adhesive,
On the main surface of the film adhesive, another film adhesive provided to cover the wiring,
An adhesive with wiring.   The adhesive with wiring according to claim 1, wherein the film-like adhesive contains conductive particles. The adhesive with wiring of Claim 1 or 2 further provided with the base material provided on the surface on the opposite side to the said main surface of the said film adhesive. The adhesive with wiring according to any one of claims 1 to 3, wherein the another film adhesive contains conductive particles.   A circuit connection structure provided with the circuit board to which the said wiring of the adhesive agent with a wiring as described in any one of Claims 1-4 was connected.

Images