JP5008971B2 - Wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wiring board used as a component of an electronic device and a manufacturing method thereof.

  In recent years, in the electronic equipment field, with the increase in the density of electronic equipment, flexible printed wiring boards are widely used for applications such as wiring to movable parts of electronic equipment. In addition, with the miniaturization and high functionality of electronic devices, flexible printed wiring boards having various shapes formed by connecting a plurality of flexible printed wiring boards are used.

  As a connection structure of a plurality of flexible printed wiring boards, for example, a connection structure using a connector is used. More specifically, there is disclosed a flexible printed wiring board in which a connector connection portion is formed at an end portion, and a connection terminal is formed on a conductor circuit whose surface is exposed in the connector connection portion. And it is the structure which connects a some flexible printed wiring board by inserting the said connection terminal in the connector insertion port formed in the connector (for example, refer patent document 1).

  However, since the connector for connecting the flexible printed wiring board needs to be provided in the connection using the connector described above, the connection structure of the flexible printed wiring board is complicated, and a space depending on the thickness of the connector is required. There was a problem that it was not possible to cope with the downsizing of electronic devices.

Therefore, an anisotropic conductive adhesive in which a conductive substance is dispersed in a thermosetting resin is used instead of using the connector described above in order to reduce the size of electronic devices and save space. A structure for connecting a plurality of flexible printed wiring boards is known. More specifically, the 1st provided on the 1st substrate of the 1st flexible printed wiring board by performing heat press processing via the anisotropic conductive adhesive which is an adhesive layer. The first and second flexible printed wiring boards are connected by electrically connecting the second conductive circuit and the second conductive circuit provided on the second base of the second flexible printed wiring board. A structure is disclosed (for example, see Patent Document 2).
JP 2003-101167 A JP 2002-314216 A

  However, in the connection described in Patent Document 2, since the contact portion between the conductor circuit and the adhesive layer is a flat surface, the conductor circuit and the adhesive layer may be peeled off. There was a problem of shortage. In addition, in order to improve the adhesive strength between the conductor circuit and the adhesive layer, it is necessary to increase the space of the conductor circuit in contact with the adhesive layer, which is sufficient for miniaturization and space saving of electronic devices. There was a problem that could not be done.

  Therefore, the present invention has been made in view of the above-described problems, and can improve the adhesive strength between the conductor circuit and the adhesive layer, and can cope with downsizing and space saving of electronic devices. An object of the present invention is to provide a wiring board that can be manufactured and a method for manufacturing the same.

In order to achieve the above object, the invention described in claim 1 includes a first base material, a conductor circuit formed on the first base material , a second base material, and a second base material. and a second conductor circuit formed on the first conductor circuits via the conductive adhesive layer, the second conductor circuits to a circuit board to be electrically connected, the a surface of the first conductor circuit, the first groove is formed at a portion in contact with the conductive adhesive layer, the depth of the first groove H _11, the height of the first conductor circuits H ₁₂ , the second groove portion has a relationship of 0.02H ₁₂ ≦ H ₁₁ ≦ 0.98H ₁₂ and is on the surface of the second conductor circuit and is in contact with the conductive adhesive layer. When the depth of the second groove is H ₂₁ and the height of the second conductor circuit is H ₂₂ , a relationship of 0.02H ₂₂ ≦ H ₂₁ ≦ 0.98H ₂₂ It is characterized by having .

According to this configuration, since the adhesion between the groove portions (the first groove portion and the second groove portion) and the conductive adhesive layer is improved, the conductor circuit in which the groove portions are formed (the first conductor circuit and the second groove portion) . It is possible to improve the adhesive strength between the conductor circuit) and the adhesive layer. In addition, since it is possible to improve the adhesive strength between the conductor circuit and the adhesive layer without increasing the space of the conductor circuit in contact with the adhesive layer, it is possible to reduce the size and space of electronic devices. It becomes possible. Furthermore, since the adhesive strength of the conductor circuit and the adhesive layer is improved, when using a conductive adhesive layer, it is possible to improve the first conductor circuits and the connection reliability between the second conductor circuits It becomes possible. Further, it is possible to further improve the adhesion between the groove and the adhesive layer and the adhesive strength between the conductor circuit in which the groove is formed and the adhesive layer.

The invention according to claim 2 is the wiring board according to claim 1, wherein a plurality of first groove portions are formed, and each of the plurality of first groove portions has a depth of the groove portion of H ₁₁ , the height of the first conductor circuit is an _{H 12,} have a relation of _{0.02H 12 ≦ H 11 ≦ 0.98H 12} , the second groove is formed with a plurality, the plurality of second respective groove However, when the depth of the groove is H ₂₁ and the height of the second conductor circuit is H ₂₂ , the relationship is 0.02H ₂₂ ≦ H ₂₁ ≦ 0.98H ₂₂ .

A third aspect of the present invention is the wiring board according to the first or second aspect, wherein the surface of the first groove and the surface of the second groove have an uneven shape. According to this configuration, it is possible to further improve the adhesion between the groove and the adhesive layer and the adhesive strength between the conductor circuit in which the groove is formed and the adhesive layer.

Invention of Claim 4 is a wiring board as described in any one of Claim 1 thru | or 3 , Comprising: At least one of a 1st base material and a 2nd base material is a flexible base material It is characterized by being.

Invention of Claim 5 is a wiring board as described in any one of Claim 1 thru | or 3 , Comprising: At least one of a 1st base material and a 2nd base material is a rigid base material It is characterized by being.

The invention of claim 6 includes a first substrate, a first conductor circuit formed on the first substrate, a second substrate, which is formed on the second substrate and a second conductive circuit, the first conductor circuits via the conductive adhesive layer, the second conductor circuits be electrically connected to the production method of the wiring board, the first Forming a first conductor circuit on the substrate, forming a second conductor circuit on the second substrate, and forming a first resist layer on the first conductor circuit; , exposure and development, forming a predetermined first resist pattern in the first resist layer, a first resist layer having a first resist pattern as a mask, the first conductive circuit, the etching by selectively removed by, a surface of the first conductive circuit, a portion in contact with the conductive adhesive layer, A first groove forming step of forming a first groove, and forming a second resist layer to the second conductor circuit on, exposure and development process, a predetermined in the second resist layer a second resist pattern And a step of selectively removing the second conductor circuit by etching using the second resist layer having the second resist pattern as a mask, and a surface of the second conductor circuit, A second groove portion forming step for forming a second groove portion in a portion in contact with the conductive adhesive layer. In the first groove portion forming step, the depth of the first groove portion is H ₁₁ , and the first conductor is formed. Etching is performed so that the relationship of 0.02H ₁₂ ≦ H ₁₁ ≦ 0.98H ₁₂ is established when the height of the circuit is H _12, and the depth of the second groove is formed in the second groove forming step. the _{H 21,} the height of the second conductor circuit When the H _22, as relation between 0.02H ₂₂ ≦ _{H 21} ≦ 0.98H ₂₂ is satisfied, and performs etching.

According to this configuration, when the first conductor circuit is electrically connected to the second conductor circuit via the conductive adhesive layer, the adhesiveness with the conductive adhesive layer is excellent. Groove portions (first groove portion and second groove portion) are formed, and have conductor circuits (first conductor circuit and second conductor circuit) excellent in adhesive strength with the conductive adhesive layer, A wiring board capable of improving the connection reliability between the first conductor circuit and the second conductor circuit can be manufactured. In addition, the adhesive strength between the conductor circuit and the adhesive layer can be improved without increasing the space of the conductor circuit in contact with the adhesive layer, which is sufficient for downsizing and space saving of electronic devices. A wiring board that can be used can be manufactured. Further improvements, in forming a groove on the conductor circuit, without causing cracks or the like in the conductor circuit, it is possible to form a groove, a first conductor circuit and the second connection reliability of the conductor circuits It becomes possible to make it. In addition, it is possible to obtain a wiring board capable of further improving the adhesion between the groove and the conductive adhesive layer, and the adhesive strength between the conductive circuit in which the groove is formed and the conductive adhesive layer. .

The invention according to claim 7 is the method for manufacturing the wiring board according to claim 6, wherein in the first groove portion forming step, a plurality of first groove portions are formed, and each of the plurality of first groove portions is formed. Etching is performed so that the relationship of 0.02H ₁₂ ≦ H ₁₁ ≦ 0.98H ₁₂ is established when the depth of the groove is H ₁₁ and the height of the first conductor circuit is H ₁₂ . in the second groove portion forming step, the forming a plurality of second groove portions, when each of the plurality of second grooves, the depth of the groove H _21, the height of the second conductor circuit was H ₂₂ In addition , the etching is performed so that the relationship of 0.02H ₂₂ ≦ H ₂₁ ≦ 0.98H ₂₂ is established.

Invention of Claim 8 is a manufacturing method of the wiring board of Claim 6 or Claim 7, Comprising: It is uneven | corrugated shape on the surface of a 1st groove part, and the surface of a 2nd groove part by etching. It is characterized by forming. According to this configuration, it is possible to obtain a wiring plate that can further improve the adhesion between the groove and the adhesive layer and the adhesive strength between the conductor circuit in which the groove is formed and the adhesive layer.

Invention of Claim 9 is a manufacturing method of the wiring board as described in any one of Claim 6 thru | or 8 , Comprising: At least one of a 1st base material and a 2nd base material is flexible. It is a characteristic base material.

Invention of Claim 10 is a wiring board as described in any one of Claim 6 thru | or 8 , Comprising: At least one of a 1st base material and a 2nd base material is a rigid base material It is characterized by being.

According to the present invention, a first substrate, a first conductor circuit formed on the first substrate, a second substrate, a second formed on the second substrate and a conductor circuit, the first conductor circuits via the conductive adhesive layer, the wiring board is electrically connected to the second conductor circuits, conductor circuits (first conductor circuits and the second It is possible to improve the adhesive strength between the conductive circuit) and the conductive adhesive layer. In addition, it is possible to cope with downsizing and space saving of electronic devices. Furthermore, when using a conductive adhesive layer, it is possible to improve the first conductor circuits and connection reliability between the second conductor circuits. In addition, it is possible to further improve the adhesion between the groove portions (the first groove portion and the second groove portion) and the adhesive layer, and the adhesive strength between the conductor circuit in which the groove portions are formed and the adhesive layer.

  Hereinafter, a preferred embodiment of the present invention will be described. FIG. 1 is a cross-sectional view showing a configuration of a multilayer flexible printed wiring board that is a wiring board assembly having a wiring board according to an embodiment of the present invention, and FIG. 2 is an outline of the wiring board according to the embodiment of the present invention. It is sectional drawing which shows a structure. FIG. 3 is a sectional view showing a schematic configuration of a wiring board constituting the multilayer flexible printed wiring board which is the wiring board assembly shown in FIG. In the present embodiment, a flexible printed wiring board having a conductor circuit formed on a flexible base material will be described as an example of the wiring board.

  As shown in FIG. 1, the multilayer flexible printed wiring board 1 of the present embodiment is obtained by bonding flexible printed wiring boards 2 and 3 via an adhesive layer 30. As shown in FIG. 2, the flexible printed wiring board 2 is a so-called single-sided flexible print in which a conductor circuit 5 having a predetermined conductor pattern is formed on one side of a flexible substrate 4 formed of a flexible resin film. It is a wiring board, Comprising: The coverlay film 6 which is an insulating layer is provided so that the said conductor circuit 5 may be covered. Here, the “insulating layer” means a layer for protecting the conductor circuit 5 and includes the cover lay film 6 and the cover coat layer. The conductor circuit 5 may be provided via an adhesive layer (not shown). However, in consideration of the flexibility and dimensional stability of the flexible printed wiring board 2, without using the adhesive layer, The conductor circuit 5 is preferably provided on the surface of the material 4.

  In addition, as shown in FIG. 2, in the flexible printed wiring board 2, the conductor circuit 5 is electrically connected to the conductor circuit 14 (see FIG. 3 described later) provided on the flexible printed wiring board 3 which is another wiring board. An opening 8 is formed in the cover lay film 6 so as to be connected to the surface, and a part of the surface 5a of the conductor circuit 5 is exposed from the opening 8 to the outside.

  In addition, as shown in FIG. 2, the coverlay film 6 is composed of an adhesive layer 9 laminated on the conductor circuit 5 and a resin film 10 laminated thereon so as to cover the conductor circuit 5.

  The flexible printed wiring board 3 is a so-called single-sided flexible printed wiring board having a conductor circuit 14 which is another conductor circuit having a predetermined conductor pattern on one side of a flexible substrate 11 formed of a flexible resin film. Thus, a cover lay film 16 that is an insulating layer is provided so as to cover the conductor circuit 14. In this case, the conductor circuit 14 may be provided via an adhesive layer (not shown), but the conductor circuit 14 is provided on the surface of the substrate 11 without using the adhesive layer. It can also be.

  As shown in FIG. 3, in the flexible printed wiring board 3, the opening 7 is formed in the coverlay film 16 in order to electrically connect the conductive circuit 14 to the conductive circuit 5 provided on the flexible printed wiring board 2. From the opening 7, a part of the surface 14a of the conductor circuit 14 is exposed to the outside.

  As shown in FIG. 3, the cover lay film 16 is composed of an adhesive layer 19 laminated on the conductor circuit 14 and a resin film 20 laminated thereon so as to cover the conductor circuit 14.

  As shown in FIG. 1, the conductive circuit 5 provided on the flexible printed wiring board 2 and the conductive circuit 14 provided on the flexible printed wiring board 3 are electrically connected via an adhesive layer 30. It has become.

  As a resin film which comprises the base materials 4 and 11, what consists of a resin material excellent in the softness | flexibility is used. As such a resin film, for example, any resin film that is versatile for a flexible printed wiring board, such as a polyester film, can be used. In addition, it is particularly preferable that the resin film has high heat resistance in addition to flexibility, and examples of the resin film include polyamide resin films, polyimide resin films such as polyimide and polyamideimide, and polyethylene. Naphthalate is preferably used.

  Moreover, as the resin films 10 and 20, the thing similar to the resin film which comprises the above-mentioned base materials 4 and 11 can be used. The adhesive constituting the adhesive layers 9 and 19 is preferably an adhesive having excellent flexibility and heat resistance. Examples of such an adhesive include nylon, epoxy resin, butyral resin, and acrylic resin. And various resin adhesives. Moreover, as the metal foil constituting the conductor circuits 5 and 14, a copper foil or the like is preferably used.

  In the present embodiment, a conductive adhesive is used as the adhesive layer 30 that electrically connects the conductor circuits 5 and 14. As the conductive adhesive, for example, an insulating thermosetting resin such as an epoxy resin as a main component and a conductive substance dispersed in the resin can be used. For example, an epoxy resin in which a powder of a conductive substance such as copper, silver, or graphite is dispersed can be used. By using such a conductive adhesive, it is possible to connect the conductor circuit 5 to the conductor circuit 14 with a low conductive resistance, so that the conductivity between the conductor circuit 5 and the conductor circuit 14 is improved. Can do.

  In the present embodiment, an anisotropic conductive adhesive containing a conductive material can be used for the adhesive layer 30. More specifically, as the anisotropic conductive adhesive, for example, an insulating thermosetting resin such as the above-described epoxy resin is a main component, and fine particles (for example, spherical metal fine particles) are contained in the resin. And conductive material 24 (see FIG. 4) having a so-called large aspect ratio, which has a large number of metal fine particles made of spherical resin particles plated with metal, a linearly connected shape, or a needle shape. Distributed ones can be used. The aspect ratio here refers to the ratio of the short diameter R (the length of the cross section of the conductive material) and the long diameter L (the length of the conductive material) of the conductive material 24.

  Further, the metal fine particles used in the present invention preferably include a ferromagnetic material in part, such as a single metal having ferromagnetism, two or more kinds of alloys having ferromagnetism, a metal having ferromagnetism, and the like. It is preferably any one of an alloy with the above metal and a composite containing a metal having ferromagnetism. This is because the use of a ferromagnetic metal makes it possible to orient the conductive material 24 using a magnetic field due to the magnetism of the metal itself. For example, nickel, iron, cobalt, and two or more kinds of alloys thereof can be used.

  The aspect ratio of the conductive material 24 is preferably 10 or more. By using such a conductive material 24, when an anisotropic conductive adhesive is used as the adhesive layer 30, the contact probability between the conductive materials 24 is increased. Therefore, it is possible to connect the conductor circuit 5 to the conductor circuit 14 without increasing the blending amount of the conductive material 24.

  The aspect ratio of the conductive material 24 is directly measured by a method such as observation with a CCD microscope. In the case of the conductive material 24 whose cross section is not a circle, the aspect ratio is obtained by setting the maximum length of the cross section as the short diameter R. Further, the conductive material 24 does not necessarily have a straight shape, and can be used without any problem even if there is some bending or branching. In this case, the aspect ratio is obtained with the maximum length of the conductive material as the major axis L.

  Moreover, it is desirable that the short diameter R of the conductive material 24 is 1 μm or less. By using such a conductive material 24, when an anisotropic conductive adhesive is used as the adhesive layer 30, the contact probability between the conductive materials 24 is further increased. It becomes possible to connect between the conductor circuit 5 and the conductor circuit 14 with the blending amount of 24.

  Here, the present embodiment is characterized in that a groove portion 15 is formed on the surface 5a of the conductor circuit 5 as shown in FIGS. More specifically, the surface 5a of the conductor circuit 5 that is in contact with the conductive adhesive layer 30 (that is, the portion of the conductor circuit 5 that is connected to the conductor circuit 14 via the adhesive layer 30). And the groove part 15 is formed in the exposed part of the surface 5a of the conductor circuit 5 shown in FIG.

  With such a configuration, since the contact area between the conductor circuit 5 and the adhesive layer 30 increases, the adhesion between the groove 15 and the adhesive layer 30 is improved, and the adhesive strength between the groove 15 and the adhesive layer 30 is improved. It will be. In addition, the adhesive strength between the conductor circuit 5 and the adhesive layer 30 can be improved without increasing the space of the conductor circuit 5 in contact with the adhesive layer 30.

From the viewpoint of further improving the adhesion between the groove 15 and the adhesive layer 30 and the adhesive strength, the depth of the groove 15 is H ₁ and the height of the conductor circuit 5 is H ₂ (see FIG. 5). In this case, it is preferable that the relationship 0.02H ₂ ≦ H ₁ ≦ 0.98H ₂ is established. This is because, when 0.02H ₂ > H ₁ , the depth H ₁ of the groove 15 is considerably smaller than the height H ₂ of the conductor circuit 5, and therefore the contact between the conductor circuit 5 and the adhesive layer 30. The effect of increasing the area is reduced, and when H ₁ > 0.98H ₂ , the depth H ₁ of the groove 15 is increased. This is because when the conductor circuits 5 and 14 are connected via the connector 30, the necessity for high-voltage mounting may occur, and the connection process of the conductor circuits 5 and 14 may be complicated. For example, when the height H ₂ of the conductor circuit 5 is 18 μm, the depth H ₁ of the groove 15 is preferably ₁ to 17 μm. When the height H ₂ of the conductor circuit 5 is 35 μm, the height of the groove 15 H ₁ is preferably ₁ to 34 μm.

  Moreover, as shown in FIG. 5, it is preferable that the surface 15a of the groove portion 15 has an uneven shape. With such a configuration, since the adhesive layer 30 bites into the surface 15a of the groove portion 15 having the concavo-convex shape, the adhesiveness between the groove portion 15 and the adhesive layer 30, and the conductor circuit 5 in which the groove portion 15 is formed and the adhesive The adhesive strength of the layer 30 is further improved.

  Next, an example of a method for manufacturing the flexible printed wiring board 2 will be described with reference to the drawings. First, the laminated body in which the conductor circuit 5 is formed on the base material 4 shown in FIG. More specifically, a metal foil such as a copper foil is laminated on the surface of the substrate 4 formed of a flexible resin film, and the metal foil is etched by a conventional method to form the conductor circuit 5. Here, “etching” means removing (thinning) the conductor circuit 5 to a thickness exceeding 1 μm or a method therefor.

  Next, the conductor circuit 5 is selectively removed, and a groove portion 15 having an uneven surface 15 a is formed on the surface 5 a of the conductor circuit 5. The conductor circuit 5 can be selectively removed by various methods. In this embodiment, etching using a resist mask formed by exposing and developing a resist material, or soft etching (flash etching). Or also called light etching). Here, “soft etching” means removing (thinning) the conductor circuit 5 to a thickness of 1 μm or less, or a method for that purpose.

  More specifically, as shown in FIG. 6B, first, a resist layer 25 is formed by applying or laminating a resist material on the conductor circuit 5 laminated on the substrate 4. For example, the resist layer 25 can be formed by laminating and laminating a thin dry film resist of 15 to 25 μm on the conductor circuit 5. Alternatively, the resist layer 25 may be formed by applying and curing a photoresist.

  Next, pattern exposure is performed on the formed resist layer 25 under a predetermined condition using a predetermined exposure light source, and unnecessary portions are dissolved and removed with a predetermined developer (for example, sodium carbonate aqueous solution). For example, when the negative resist layer 25 is used, a light irradiated portion remains by exposure and development processing. By such exposure and development processing, a predetermined resist pattern is formed on the resist layer 25 as shown in FIG.

  Next, as shown in FIG. 6D, by using the resist layer 25 having a resist pattern as a mask, the conductor circuit 5 is selectively removed by etching or soft etching to form the surface 5a of the conductor circuit 5. Thus, the groove portion 15 having the concavo-convex surface 15 a is formed in a portion in contact with the conductive adhesive layer 30. Next, as shown in FIG. 6E, the used resist layer 25 is peeled off from the conductor circuit 5 and removed.

  Next, as shown in FIG. 6 (f), the cover lay film 6 in which the opening 8 is formed is disposed above the conductor circuit 5 by punching or drilling. Then, as shown in FIG. 6 (g), the groove 15 of the conductor circuit 5 and the opening 8 of the coverlay film 6 are aligned, and the adhesive layer 9 of the coverlay film 6 is placed on the conductor circuit 5. The flexible printed wiring board 2 shown in FIG. 2 is manufactured by placing the cover lay film 6 on the conductor circuit 5.

  As described above, since the conductor circuit 5 is formed on a metal foil such as a copper foil, in the etching step (or soft etching step) in this embodiment, the copper foil or the like that forms the conductor circuit 5 is used. An etching solution (or soft etching solution) that can be dissolved and selectively removed is used.

As this etching solution, for example, cupric chloride or ferric chloride can be used. In addition, when performing soft etching, the etching liquid etc. which have a sulfuric acid and hydrogen peroxide as a main component can be used. Moreover, as processing temperature in the etching process using the said etching liquid, 30-50 degreeC is preferable and 60-300 second is preferable as processing time. Among these, as in this embodiment, when forming the groove 15 having the uneven surface 15a on the surface 5a of the conductor circuit 5, cupric chloride or ferric chloride is used as an etching solution. It is particularly preferred. Further, from the viewpoint of establishing the above-described relationship of 0.02H ₂ ≦ H ₁ ≦ 0.98H ₂ , it is particularly preferable to perform the treatment at a treatment temperature of 30 to 50 ° C. for 60 to 300 seconds. However, when the depth H ₁ of the groove 15 is small in the above-described range of 0.02H ₂ ≦ H ₁ ≦ 0.98H ₂ (for example, when H ₁ = 0.02H ₂ ), soft etching is performed. The temperature of is preferably 20 to 40 ° C., and the condition that the copper foil constituting the conductor circuit 5 is dissolved by about 0.5 to 2 μm (about 1 minute in terms of time) is preferable.

  In the present embodiment, as described above, the groove 15 is formed in the connection portion of the conductor circuit 5 by etching (or soft etching), so that no stress is applied to the conductor circuit 5 from the outside. The groove portion 15 can be formed. Therefore, when forming the groove 15 in the conductor circuit 5, the groove 15 can be formed without generating cracks or the like in the conductor circuit 5, thereby improving the connection reliability between the conductor circuit 5 and the conductor circuit 14. It becomes possible.

  In addition, the manufacturing method of the flexible printed wiring board 3 can be manufactured similarly to the past. That is, on the base material 11 formed of a flexible resin film, a laminated body in which the conductor circuit 14 is formed is produced in the same manner as in the case of FIG. In the same manner as in (f) and (g), the adhesive layer 19 of the cover lay film 16 is placed on the conductor circuit 14 and the cover lay film 16 is bonded to the conductor circuit 14 to thereby The flexible printed wiring board 3 shown in FIG.

  Next, an example of a method for connecting the conductor circuit 5 of the flexible printed wiring board 2 and the conductor circuit 14 of the flexible printed wiring board 3 through the adhesive layer 30 will be described with reference to the drawings.

  First, as shown in FIG. 7A, an adhesive layer 30 containing a conductive material 24 containing a thermosetting resin such as an epoxy resin as a main component, for example, between flexible printed wiring boards 2 and 3. An anisotropic conductive adhesive is interposed. Next, as shown in FIG. 7A, the head 26 that is a crimping member is installed above the flexible printed wiring board 3. And the said head 26 is moved to the direction of the arrow X in a figure, and as shown in FIG.7 (b), the said anisotropically conductive adhesive agent is a flexible printed wiring board via the flexible printed wiring board 3. As shown in FIG. The anisotropic conductive adhesive is heated and melted at a predetermined pressure in the direction 2 and heated to the curing temperature. As described above, since the anisotropic conductive adhesive is mainly composed of a thermosetting resin, the anisotropic conductive adhesive softens once when heated at a predetermined curing temperature. It will harden | cure by continuing the said heating. When a preset curing time of the anisotropic conductive adhesive has elapsed, the heating state by the head 26 is released, the maintenance state of the curing temperature of the anisotropic conductive adhesive is released, and cooling is started. 1, a multilayer flexible printed wiring board 1 which is a wiring board assembly composed of flexible printed wiring boards 2 and 3 to which conductor circuits 5 and 14 are connected via an anisotropic conductive adhesive is manufactured. .

According to the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment, the groove portion 15 is formed on the surface 5 a of the conductor circuit 5 of the flexible printed wiring board 2 and in a portion in contact with the conductive adhesive layer 30. Therefore, since the adhesiveness between the groove 15 and the adhesive layer 30 is improved, it is possible to improve the adhesive strength between the conductor circuit 5 in which the groove 15 is formed and the adhesive layer 30. In addition, since it is possible to improve the adhesive strength between the conductor circuit 5 and the adhesive layer 30 without increasing the space of the conductor circuit 5 in contact with the adhesive layer 30, it is possible to reduce the size and space of electronic devices. It becomes possible to cope with the conversion. Furthermore, since the adhesive strength between the conductor circuit 5 and the adhesive layer 30 is improved, the connection reliability between the conductor circuit 5 and the conductor circuit 14 is improved when the conductive adhesive layer 30 is used.

(2) In the present embodiment, when the depth of the groove 15 is H ₁ and the height of the conductor circuit 5 is H ₂ , a configuration in which the relationship of 0.02H ₂ ≦ H ₁ ≦ 0.98H ₂ is established. It is said. Therefore, the adhesion between the groove 15 and the adhesive layer 30 and the adhesive strength between the conductor circuit 5 in which the groove 15 is formed and the adhesive layer 30 are further improved.

  (3) In this embodiment, it is set as the structure which forms uneven | corrugated shape in the surface 15a of the groove part 15. As shown in FIG. Accordingly, it is possible to further improve the adhesion between the groove and the adhesive layer and the adhesive strength between the conductor circuit in which the groove is formed and the adhesive layer.

  (4) In the method for manufacturing the flexible printed wiring board 2 of the present embodiment, the conductor circuit 5 is selectively removed by etching using the resist layer 25 formed on the conductor circuit 5 and having a resist pattern as a mask. The groove portion 15 is formed on the surface 5a of the conductor circuit 5 in the portion that contacts the conductive adhesive layer 30. Therefore, when the conductor circuit 5 is electrically connected to the conductor circuit 14 via the conductive adhesive layer 30, the groove portion 15 having excellent adhesion to the adhesive layer 30 is formed, and adhesion is performed. The flexible printed wiring board 2 which has the conductor circuit 5 excellent in adhesive strength with the agent layer 30 and can improve the connection reliability between the conductor circuit 5 and the conductor circuit 14 can be manufactured. In addition, since it is possible to improve the adhesive strength between the conductor circuit 5 and the adhesive layer 30 without increasing the space of the conductor circuit 5 in contact with the adhesive layer 30, it is possible to reduce the size and space of electronic devices. It is possible to manufacture a wiring board that can sufficiently cope with the process. Furthermore, when forming the groove 15 in the conductor circuit 5, the groove 15 can be formed without causing cracks or the like in the conductor circuit 5, thereby improving the connection reliability between the conductor circuit 5 and the conductor circuit 14. It becomes possible.

In addition, you may change the said embodiment as follows.
As shown in FIG. 8, in the flexible printed wiring board 3, like the groove portion 15 of the flexible printed wiring board 2, on the surface 14 a of the conductor circuit 14, the portion that contacts the conductive adhesive layer 30, While forming the groove part 31, it is good also as a structure which forms in the surface 31a of the said groove part 31 the uneven | corrugated shape demonstrated in FIG. Thus, by providing the groove portions 15 and 31 in each of the conductor circuits 5 and 14 of the flexible printed wiring boards 2 and 3, and connecting the conductor circuits 5 and 14 through the conductive adhesive layer 30, Not only the groove 15 and the adhesive layer 30 but also the adhesion between the groove 31 and the adhesive layer 30 and the adhesive strength between the conductor circuit 14 and the adhesive layer 30 are improved. As a result, the connection reliability between the conductor circuit 5 and the conductor circuit 14 is further improved.

  Further, instead of the flexible printed wiring board 2, a rigid wiring board 37 in which a conductor circuit 36 is formed on a rigid base 35 shown in FIG. 9 may be used as the wiring board. In this case as well, like the groove portion 15 of the flexible printed wiring board 2, the groove portion 38 is formed on the surface 36 a of the conductor circuit 36 in the portion that contacts the conductive adhesive layer 30. It is good also as a structure which forms the uneven | corrugated shape demonstrated in FIG. With such a configuration, it is possible to obtain the same effect as when the above-described flexible printed wiring board 2 is used. In addition, the formation method of the groove part 38 can use the method similar to the formation method of the above-mentioned groove part 15. FIG.

  As a wiring board constituting the wiring board assembly, as shown in FIG. 10, a rigid wiring board 41 in which another conductor circuit 40 is formed on the above-described rigid wiring board 37 and a rigid base 39. It is good also as a structure which uses. In this case as well, like the groove portion 15 of the flexible printed wiring board 2, the groove portion 42 is formed on the surface 40 a of the conductor circuit 40 in the rigid wiring board 41 and in contact with the conductive adhesive layer 30. It is good also as a structure which forms the uneven | corrugated shape demonstrated in FIG. 5 in the surface 42a of the said groove part 42 while forming. Thus, by providing the groove portions 38 and 42 in the respective conductor circuits 36 and 40 of the rigid wiring boards 37 and 41 and connecting the conductor circuits 36 and 40 through the conductive adhesive layer 30, the groove portions are obtained. 38 and the adhesive layer 30 as well as the adhesion between the groove 42 and the adhesive layer 30 and the adhesive strength between the conductor circuit 40 and the adhesive layer 30 are improved. As a result, the connection reliability between the conductor circuits 36 and 40 is further improved. In addition, the formation method of the groove part 42 can use the method similar to the formation method of the above-mentioned groove part 15. FIG.

  1 and FIG. 9 described above, instead of the flexible printed wiring board 3, the above-described conductor circuit 5 (or conductor circuit 36) is, for example, Au plated via the conductive adhesive layer 30. It may be configured to be electrically connected to an electronic component (not shown) such as an IC chip having bumps. With such a configuration, the same effects as in the case of using the flexible printed wiring board 3 in FIGS. 1 and 9 can be obtained. In this case, the joined body of the flexible printed wiring board 2 including the conductor circuit 5 (or the rigid wiring board 37 including the conductor circuit 36) and the IC chip can be manufactured in the same manner as before. That is, for example, in FIG. 7 described above, an IC chip on which Au plating bumps are arranged is used instead of the flexible printed wiring board 3. Then, similarly to the case of FIG. 7, an anisotropic conductive adhesive that is an adhesive layer 30 containing the conductive substance 24 is interposed between the flexible printed wiring board 2 and the IC chip. Next, as in the case of FIG. 7, the head 26 which is a crimping member is moved, and the anisotropic conductive adhesive is pressurized at a predetermined pressure in the direction of the flexible printed wiring board 2 through the IC chip. In the state, the anisotropic conductive adhesive is heated and melted, heated to a curing temperature, and cooling is started. If it does so, the joined body which consists of the flexible printed wiring board 2 and IC chip to which the conductor circuit 5 and Au plating bump of IC chip were connected via anisotropic conductive adhesive will be manufactured.

  Examples of utilization of the present invention include a wiring board used as a component of an electronic device and a method for manufacturing the same.

It is sectional drawing which shows the structure of the multilayer flexible printed wiring board which is a wiring board assembly which has a wiring board which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the wiring board which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the wiring board which comprises the multilayer flexible printed wiring board which is a wiring board assembly shown in FIG. It is the schematic for demonstrating the electroconductive substance used for the anisotropic conductive adhesive in embodiment of this invention. It is the schematic for demonstrating the surface of the groove part of the wiring board which concerns on embodiment of this invention. (A)-(g) is a figure for demonstrating the manufacturing method of the wiring board which concerns on embodiment of this invention. (A)-(b) is a figure for demonstrating the connection method of the conductor circuit of the wiring board shown in FIG. 2, FIG. It is sectional drawing for demonstrating the modification of the wiring board shown in FIG. It is sectional drawing for demonstrating the modification of the wiring board which concerns on embodiment of this invention. It is sectional drawing for demonstrating the modification of the wiring board which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer flexible printed wiring board, 2 ... Flexible printed wiring board, 3 ... Flexible printed wiring board, 4 ... Base material, 5 ... Conductor circuit, 5a ... Surface of conductor circuit, 11 ... Base material, 14 ... Other conductor circuit 14a ... surface of another conductor circuit, 15 ... groove portion, 15a ... surface of the groove portion, 24 ... conductive material, 25 ... resist layer, 30 ... conductive adhesive layer, 31 ... groove portion, 31a ... surface of the groove portion, 35 ... base material, 36 ... conductor circuit, 36a ... surface of conductor circuit, 37 ... rigid wiring board, 38 ... groove part, 38a ... surface of groove part, 39 ... base material, 40 ... other conductor circuit, 40a ... other conductor the surface of the circuit, 41 ... rigid wiring board, 42 ... groove, 42a ... surface of the groove, H 1 _... groove depth, the height of the H 2 _... conductor circuit

Claims (10)

A first substrate, a first conductor circuit formed on the first substrate on a second substrate and a second conductive circuit formed on said second substrate wherein the first conductor circuits via the conductive adhesive layer, the second conductor circuits to a circuit board to be electrically connected,
A first groove is formed on a surface of the first conductor circuit and in contact with the conductive adhesive layer, the depth of the first groove is H ₁₁ , and the first conductor circuit is formed. When the height of H ₁₂ is H ₁₂ , the relationship of 0.02H ₁₂ ≦ H ₁₁ ≦ 0.98H ₁₂ is satisfied ,
A second groove is formed on the surface of the second conductor circuit and in contact with the conductive adhesive layer. The depth of the second groove is set to H ₂₁ , and the second conductor circuit is formed. the height when the _{H 22,} have a relation of 0.02H ₂₂ ≦ _{H 21} ≦ 0.98H ₂₂
Wiring board you wherein a. When a plurality of the first groove portions are formed, and each of the plurality of first groove portions has a depth of H ₁₁ and the height of the first conductor circuit is H ₁₂ , 0.02H has a relationship of ₁₂ ≦ _{H 11} ≦ 0.98H _12,
When a plurality of the second groove portions are formed, and each of the plurality of second groove portions has a depth of H ₂₁ and the height of the second conductor circuit is H ₂₂ , 0.02H have a relationship of ₂₂ ≦ _{H 21} ≦ 0.98H ₂₂
The wiring board according to claim 1. The wiring board according to claim 1, wherein the surface of the first groove and the surface of the second groove have an uneven shape. The wiring board according to any one of claims 1 to 3, wherein at least one of the first base material and the second base material is a flexible base material . The wiring board according to any one of claims 1 to 3, wherein at least one of the first base material and the second base material is a rigid base material . A first substrate, a first conductor circuit formed on the first substrate on a second substrate and a second conductive circuit formed on said second substrate wherein the first conductor circuits via the conductive adhesive layer, a electrically connected to the manufacturing method of wiring board in the second conductor circuits,
Forming a first conductive circuit on the first substrate,
Forming the second conductor circuit on the second substrate;
Forming a first resist layer on the first conductor circuit;
Exposure and development, forming a predetermined first resist pattern on said first resist layer,
As a mask the first resist layer having the first resist pattern, the first conductive circuit, by selectively removed by etching, a surface of the first conductive circuit, the conductive the portion contacting the sex of the adhesive layer, and the first groove portion forming step of forming a first groove,
Forming a second resist layer on the second conductor circuit;
Forming a predetermined second resist pattern on the second resist layer by exposure and development; and
Using the second resist layer having the second resist pattern as a mask, the second conductor circuit is selectively removed by etching to form a surface of the second conductor circuit, and the conductive layer Including a second groove portion forming step of forming a second groove portion in a portion that contacts the adhesive adhesive layer,
In the first groove portion forming step, a depth of the first groove _{H 11,} the height of the first conductor circuit is an _{H 12,} of 0.02H ₁₂ ≦ _{H 11} ≦ 0.98H ₁₂ Etching so that the relationship is established,
In the second groove portion forming step, a depth of the second groove when _{the H 21,} the height of the second conductor circuit and a _{H 22,} of 0.02H ₂₂ ≦ _{H 21} ≦ 0.98H ₂₂ Etching so that the relationship is established
A method for manufacturing a wiring board. In the first groove portion forming step, a plurality of the first groove portions are formed, and each of the plurality of first groove portions has a depth of H ₁₁ and a height of the first conductor circuit of H. ₁₂ and etching is performed so that the relationship of 0.02H ₁₂ ≦ H ₁₁ ≦ 0.98H ₁₂ is satisfied,
In the second groove portion forming step, a plurality of the second groove portions are formed, and each of the plurality of second groove portions has a depth of the groove portion of H ₂₁ and a height of the second conductor circuit of H. ₂₂ , etching is performed so that the relationship of 0.02H ₂₂ ≦ H ₂₁ ≦ 0.98H ₂₂ is satisfied.
The method for manufacturing a wiring board according to claim 6. The method for manufacturing a wiring board according to claim 6, wherein an uneven shape is formed on the surface of the first groove and the surface of the second groove by performing the etching. The method for manufacturing a wiring board according to any one of claims 6 to 8, wherein at least one of the first base material and the second base material is a flexible base material . The method for manufacturing a wiring board according to any one of claims 6 to 8, wherein at least one of the first base material and the second base material is a rigid base material .

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