JP2013153114A - Printed wiring board, printed wiring board connection structure using printed wiring board, and manufacturing method of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board which achieves high connection reliability in the printed wiring board thermocompression bonded to another connected body through a conductive adhesive, and a printed wiring board connection structure using the printed wiring board and a manufacturing method of the printed wiring board.SOLUTION: A printed wiring board 10 includes at least a connection region S where an electrode terminal 12a is disposed and a wiring region H where wiring 12b extended from the electrode terminal 12a is disposed. The printed wiring board 10 is thermocompression bonded to another connected body at the connection region S through a conductive adhesive 30. In the printed wiring board 10, an area near the connection region S, in the wiring region H, is formed as a small volume part R where a volume per unit length of a conductor forming the wiring 12b is smaller than a volume per unit length of a conductor forming the electrode terminal 12a.

Description

  The present invention relates to a printed wiring board, a printed wiring board connection structure using the printed wiring board, and a method for manufacturing the printed wiring board.

Various printed wiring boards are arranged in an electronic device such as a mobile phone or a hard disk device according to the application.
In such a printed wiring board, it is provided with a connection region in which electrode terminals are arranged, and is thermocompression bonded to a connected body such as another printed wiring board in the connection region via a conductive adhesive. There is what I did.
An anisotropic conductive adhesive (hereinafter referred to as ACF) having thermal adhesiveness is used as a conductive adhesive for connecting such a printed wiring board and a connected body such as another printed wiring board. There is a way.
ACF has a structure in which, for example, a powdery conductive component is dispersed in a binder (binder) such as a thermoplastic resin or a thermosetting resin.
Such an ACF is compressed in the thickness direction by heating and pressurization during thermocompression bonding, and as a result, conductive components come close to or in contact with each other to form a conductive network. ) Becomes lower.
However, at this time, the surface direction of the ACF maintains an initial state where the insulation resistance is high and the conductivity is low. Therefore, according to the ACF, while maintaining insulation between adjacent electrode terminals by the insulation resistance in the plane direction and preventing a short circuit, the connection between a large number of electrode terminals arranged in the connection region by the connection resistance in the thickness direction is prevented. Electrical connections can be made at once and each independently.
At the same time, the printed wiring board and other printed wiring boards can be mechanically firmly fixed by thermocompression bonding, and the connection area of these members can be sealed with a binder, making mounting work easy. It is.
For example, Patent Document 1 shown below shows a conventional technique for connecting (thermocompression bonding) a printed wiring board and a connected body such as another printed wiring board using such an ACF.

JP 2004-170824 A

In a printed wiring board that is connected (thermocompression bonding) to a connected body such as another printed wiring board via a conductive adhesive as shown in Patent Document 1 above, a connection formed by arranging electrode terminals It is common to provide a region and a wiring extending from the electrode terminal. Moreover, what forms an electrode terminal and wiring with a conductive metal with high heat conductivity, such as copper, is common.
Therefore, the heat applied to the connection area during thermocompression is immediately transferred from the electrode terminal to the wiring, so that the heat is not sufficiently transferred to the conductive adhesive and the conductive adhesive is sufficiently melted. There was a problem that it could not be made.
Accordingly, there is a problem that the connection strength (adhesion strength) in the connection region is insufficient, electrical and mechanical connection cannot be performed well, and high connection reliability cannot be realized.

  Therefore, the present invention solves the above-described conventional problems, and realizes high connection reliability in a printed wiring board that is thermocompression bonded to a connected body such as another printed wiring board via a conductive adhesive. It is an object of the present invention to provide a printed wiring board that can be used, a connection structure for a printed wiring board using the printed wiring board, and a method for manufacturing the printed wiring board.

  The printed wiring board of the present invention is a printed wiring board comprising at least a connection region in which electrode terminals are arranged and a wiring region in which wirings extending from the electrode terminals are arranged, and a conductive adhesive is used. In the one that is thermocompression-bonded to the other connected body in the connection region, the volume per unit length of the conductor forming the wiring in the vicinity of the connection region in the wiring region is The first feature is that the volume is smaller than the volume per unit length of the conductor forming the electrode terminal.

According to the first aspect of the present invention, the printed wiring board includes at least a connection region in which electrode terminals are arranged and a wiring region in which wirings extending from the electrode terminals are arranged. A conductor for forming the wiring in the vicinity of the connection region in the wiring region in the connection region, wherein the connection region is thermocompression-bonded with a conductive adhesive. Since the volume per unit length is a small volume part smaller than the volume per unit length of the conductor forming the electrode terminal, it is loaded on the connection region when thermocompression bonding with another connected body. It is possible to effectively delay the time during which heat is transferred from the electrode terminal to the subsequent wiring rather than the small volume portion.
Therefore, sufficient heat can be applied to the connection region, and the conductive adhesive can be sufficiently melted.
Therefore, it is possible to satisfactorily make electrical and mechanical connection between the printed wiring board and the other connected body via the conductive adhesive, and high connection reliability can be realized.

  In addition to the first feature of the present invention described above, the printed wiring board of the present invention has a volume per unit length of the conductor constituting the small volume portion, which is a unit length of the conductor constituting the electrode terminal. The second feature is that the volume per unit is about 15% to 75%.

According to the second feature of the present invention, in addition to the function and effect of the first feature of the present invention, the printed wiring board has a volume per unit length of the conductor constituting the small volume portion, Since it is about 15% to 75% of the volume per unit length of the conductor constituting the electrode terminal, the heat applied to the connection region is caused from the electrode terminal when thermocompression bonding is performed with another connected body. The time for heat transfer to the subsequent wiring rather than the small volume part can be delayed more effectively.
Therefore, the electrical and mechanical connection between the printed wiring board and the other connected body can be performed more satisfactorily through the conductive adhesive.
Therefore, higher connection reliability can be realized.

  Further, in the printed wiring board of the present invention, in addition to the first or second feature of the present invention, the small volume portion has a length in a short direction of the wiring in a plan view, and the electrode terminal in the plan view. The third feature is that the length is shorter than the length in the short direction.

  According to the third feature of the present invention, in addition to the operational effects of the first or second feature of the present invention, the printed circuit board has the small volume portion in the short direction of the wiring in a plan view. Since the length is shorter than the length of the electrode terminal in the short direction in plan view, the formation of the small volume portion can be facilitated.

  In addition to the first or second feature of the present invention, the printed wiring board of the present invention has a fourth feature that the small volume portion is formed by forming a slit in the wire.

  According to the fourth feature of the present invention, the printed wiring board is formed by forming a slit in the wiring in addition to the function and effect of the first or second feature of the present invention. Therefore, the formation of the small volume part can be facilitated.

  Moreover, in the printed wiring board of the present invention, in addition to the first or second feature of the present invention, the small volume portion is formed by making the thickness of the wiring thinner than the thickness of the electrode terminal. 5 features.

  According to the fifth feature of the present invention, in addition to the operational effects of the first or second feature of the present invention described above, the small volume portion has a thickness of the wiring and the electrode terminal. Therefore, it is possible to easily form the small volume portion.

  Moreover, the connection structure of the printed wiring board of this invention connects the printed wiring board of any one of Claims 1-5, and another to-be-connected body through a conductive adhesive. This is the sixth feature.

  According to the sixth aspect of the present invention, the printed wiring board connection structure is obtained by connecting the printed wiring board according to any one of claims 1 to 5 and another connected body with a conductive adhesive. Therefore, high electrical and mechanical connection reliability can be realized.

  In addition to the sixth feature of the present invention, the printed wiring board connection structure of the present invention has a seventh feature that the conductive adhesive is an anisotropic conductive adhesive.

  According to the seventh aspect of the present invention, in the printed wiring board connection structure, in addition to the function and effect of the sixth aspect of the present invention, the conductive adhesive is an anisotropic conductive adhesive. Therefore, it is possible to realize good conductivity in the thickness direction and good insulation in the surface direction.

  Moreover, the manufacturing method of the printed wiring board of this invention is a manufacturing method of the printed wiring board of Claim 1, Comprising: The base material layer preparation process which prepares a base material layer, and forms a conductor layer in the said base material layer A conductor layer forming step and an insulating layer coating step of covering the base material layer and the conductor layer with an insulating layer, and the conductor layer forming step includes at least an electrode terminal forming step of forming an electrode terminal; A wiring forming step of forming a wiring extending from the electrode terminal, wherein the wiring forming step has a volume per unit length of a conductor forming the wiring in the vicinity of the electrode terminal. An eighth feature is that it includes a small volume portion forming step of forming a small volume portion that is smaller than the volume per unit length of the conductor that forms the conductor.

According to the eighth aspect of the present invention, the printed wiring board manufacturing method is the printed wiring board manufacturing method according to claim 1, wherein the base material layer preparing step of preparing the base material layer, A conductor layer forming step of forming a conductor layer on the base material layer; and an insulating layer coating step of covering the base material layer and the conductor layer with an insulating layer, and the conductor layer forming step includes at least an electrode terminal. An electrode terminal forming step to be formed; and a wiring forming step to form a wiring extending from the electrode terminal, wherein the wiring forming step has a unit length of a conductor forming the wiring in the vicinity of the electrode terminal. By including a small volume part forming step in which the volume per unit is formed as a small volume part that is smaller than the volume per unit length of the conductor forming the electrode terminal, Other connected And the time of thermocompression bonding, it is possible to heat load in the connection area effectively delaying the time heat is transferred to the subsequent wiring than a small volume portion from the electrode terminals.
Therefore, sufficient heat can be applied to the connection region, and the conductive adhesive can be sufficiently melted in the connection region.
Therefore, in a printed wiring board connected to another connected body via a conductive adhesive, it is possible to perform electrical and mechanical connection well and realize high connection reliability. Can be manufactured.

According to the printed wiring board of the present invention, high connection reliability can be realized in the printed wiring board in which the electrode terminal is thermocompression bonded to the other connected body via the conductive adhesive.
Further, according to the printed wiring board connection structure of the present invention, high connection reliability can be realized. In addition, good conductivity can be realized in the thickness direction, and good insulation can be realized in the surface direction.
Moreover, according to the method for manufacturing a printed wiring board of the present invention, high connection reliability can be realized in a printed wiring board in which the electrode terminal is thermocompression bonded to the other connected body via a conductive adhesive. The printed wiring board which can be manufactured can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the connection structure of the printed wiring board which concerns on embodiment of this invention, and a printed wiring board, (a) is a whole perspective view which shows the connection structure of a printed wiring board, (b) is a whole perspective view which shows a printed wiring board. It is. It is a top view which shows the principal part of the printed wiring board which concerns on embodiment of this invention. It is sectional drawing in the AA line direction of FIG. It is sectional drawing which simplifies and shows the manufacturing method of the printed wiring board which concerns on embodiment of this invention. It is sectional drawing which simplifies and shows the manufacturing method of the printed wiring board which concerns on embodiment of this invention. It is a figure which shows the 1st modification of the printed wiring board which concerns on embodiment of this invention, (a) is a top view which shows the principal part of a printed wiring board, (b) is in the BB line direction of (a). It is sectional drawing. It is a figure which shows the 2nd modification of the printed wiring board which concerns on embodiment of this invention, (a) is a top view which shows the principal part of a printed wiring board, (b) is in the CC line direction of (a). It is sectional drawing. It is a top view which shows the principal part of the conventional printed wiring board.

  With reference to the following drawings, a printed wiring board 10 according to an embodiment of the present invention, a printed wiring board connection structure 100 using the printed wiring board 10, and a method of manufacturing the printed wiring board 10 will be described. Use for understanding. However, the following description is an embodiment of the present invention, and does not limit the contents described in the claims.

  First, a printed wiring board 10 according to an embodiment of the present invention and a printed wiring board connection structure 100 using the printed wiring board 10 will be described with reference to FIGS.

A printed wiring board 10 according to an embodiment of the present invention is a printed wiring board disposed inside an electronic apparatus such as a mobile phone or a hard disk device.
As shown in FIG. 3, the printed wiring board 10 is a so-called single-sided flexible printed wiring board having a conductor layer 12 on one side of a base material layer 11, and includes a base material layer 11, a conductor layer 12, and an insulating layer 13. It consists of.
In this embodiment, as shown in FIGS. 1 and 3, the printed wiring board 10 includes a connection region S in which the electrode terminals 12 a are arranged, and the connection region S is provided via the conductive adhesive 30. The printed wiring board connection structure 100 is formed by being electrically and mechanically connected to the connection region S of the printed wiring board 20.

The base material layer 11 serves as a base of the printed wiring board 10 and is formed of a resin film.
As a resin film, what consists of a resin material excellent in the softness | flexibility is used. For example, any material may be used as long as it is normally used as a resin film for forming a printed wiring board such as a polyimide film or a polyester film.
In particular, those having high heat resistance in addition to flexibility are desirable. For example, polyamide resin films, polyimide resin films such as polyimide and polyamideimide, and polyethylene naphthalate can be suitably used.
The heat resistant resin may be any resin as long as it is normally used as a heat resistant resin for forming a printed wiring board, such as a polyimide resin or an epoxy resin.
Note that the thickness of the base material layer 11 shown in FIG. 3 is preferably 5 μm or more, more preferably 10 μm or more. This is because if the thickness is less than 5 μm, the insulation is not sufficient.

The conductor layer 12 is a layer made of a conductive metal, and is a layer that forms electrode terminals, wirings, and the like on the printed wiring board 10.
In this embodiment, as shown in FIGS. 1 and 2, an electrode terminal 12a in which a part of the conductor layer 12 is exposed from an opening 13a formed in the insulating layer 13, and the electrode terminal 12a is extended. The wiring 12b is provided in at least the conductor layer 12.
In the present embodiment, as shown in FIG. 2, in the printed wiring board 10, a connection region S for connecting the opening 13 a in which the electrode terminal 12 a is arranged to another printed wiring board 20 as a connected body. In addition, a region where the wiring 12b extending from the electrode terminal 12a is disposed is a wiring region H.
Further, as shown in FIG. 2, in the wiring region H, in the vicinity of the connection region S, the volume per unit length of the conductor forming the wiring 12b is the volume per unit length of the conductor forming the electrode terminal 12a. Smaller volume R.
More specifically, as shown in FIGS. 2 and 3, in the vicinity of the connection region S, the length (width) E in the short direction of the wiring 12b in plan view, and the shortness of the electrode terminal 12a in plan view. The configuration is such that the small volume portion R is formed by making the wiring 12b and the electrode terminal 12a the same thickness while being shorter than the length (width) F in the hand direction.
Here, “near the vicinity of the connection region S” means a region from the outer periphery of the connection region S in the plan view shown in FIG. 2 to the outside of about 0.1 mm to 10 mm, more specifically, the connection region in the plan view. Of the outer periphery of S, the region from the outer periphery S1 in contact with the wiring 12b to the outside of about 0.1 mm to 10 mm is meant.
The volume per unit length of the conductor constituting the small volume portion R is about 15% to 75%, more preferably about 20% to 50% of the volume per unit length of the conductor constituting the electrode terminal 12a. It is desirable to do. This is because if it is less than 15%, it is easy to disconnect, and the electrical resistance increases, and if it exceeds 75%, the effect of the invention cannot be obtained.
More specifically, when the thickness of the electrode terminal 12a and the thickness of the wiring 12b are the same, the length E in the short direction of the wiring 12b constituting the small volume portion R in plan view is 35 μm. It is desirable that the thickness be about ˜200 μm, more preferably about 50 μm to 100 μm. The length G in the longitudinal direction of the wiring 12b constituting the small volume portion R in plan view is desirably 1 mm or more, more preferably 2 mm or more.
On the other hand, the length F in the short direction of the electrode terminal 12a in plan view is desirably about 50 μm to 300 μm, more preferably about 150 μm to 200 μm. The length J in the longitudinal direction of the electrode terminal 12a in plan view is desirably about 1 mm to 15 mm, more preferably about 3 mm to 5 mm. This is because if it is less than 1 mm, the connection reliability is lost, and if it exceeds 15 mm, the effect of the invention cannot be obtained.
The thickness of the conductor layer 12 is desirably about 5 μm to 50 μm, more preferably about 10 μm to 35 μm. This is because if the thickness is less than 5 μm, disconnection is easy and the electric resistance increases, and if it exceeds 50 μm, formation of the wiring 12b by etching becomes difficult.
The length K between the adjacent electrode terminals 12a is desirably about 50 μm to 300 μm, more preferably about 150 μm to 200 μm. This is because if the thickness is less than 50 μm, the insulation between the electrode terminals 12a is not sufficient, and if it exceeds 300 μm, the size cannot be reduced.
The length L adjacent to the wiring 12b constituting the small volume portion R is preferably about 50 μm to 300 μm, more preferably about 150 μm to 200 μm. This is because if the thickness is less than 50 μm, the insulation between the wirings 12b is not sufficient, and if it exceeds 300 μm, the size cannot be reduced.
Further, the length (width) M in the short direction of the wiring 12b excluding the small volume portion R in plan view is desirably about 50 μm to 300 μm, more preferably about 150 μm to 200 μm. This is because if the thickness is less than 50 μm, the insulation between the wirings 12b is not sufficient, and if it exceeds 300 μm, the size cannot be reduced.
The length N of adjacent wirings 12b excluding the small volume portion R is preferably about 50 μm to 300 μm, more preferably about 150 μm to 200 μm. This is because if the thickness is less than 50 μm, the insulation between the wirings 12b is not sufficient, and if it exceeds 300 μm, the size cannot be reduced.
For example, the electrode terminal 12a and the wiring 12b are formed by coating the surface of the base material layer 11 with a conductive metal such as copper by plating, and then etching the conductor layer 12 (so-called additive method). It can form using well-known formation methods, such as. In the present embodiment, the conductor layer 12 is formed of copper.

The insulating layer 13 is a layer for covering the base material layer 11 and the conductor layer 12 to ensure insulation of the printed wiring board 10.
As the insulating layer 13, any material may be used as long as it is normally used as an insulating material for forming an insulating layer of a printed wiring board, such as a photosensitive resist.
The thickness of the insulating layer 13 is desirably 5 μm or more, more preferably 10 μm or more. This is because if the thickness is less than 5 μm, the insulation is not sufficient.

As shown in FIG. 1, the printed wiring board 20 is a printed wiring board that is electrically and mechanically connected to the printed wiring board 10 to form a printed wiring board connection structure 100.
The configuration of the printed wiring board 20 (the base layer 21, the conductor layer 22, the electrode terminal 22a, the wiring 22b, and the insulating layer 23) is the same as that described above except that no opening is provided in the small volume portion R and the insulating layer. Since the configuration is the same as the configuration of the printed wiring board 10, the following detailed description is omitted.

The conductive adhesive 30 is for electrically and mechanically connecting the printed wiring board 10 and the printed wiring board 20.
In the present embodiment, an anisotropic conductive adhesive is used as the conductive adhesive 30.
This anisotropic conductive adhesive contains a conductive component in a binder (binder), has conductivity in the thickness direction by heating and pressurization during thermal bonding, and is insulated in the surface direction. And has an adhesive property for bonding members together.
The binder may be any one as long as it is normally used as a binder for forming an anisotropic conductive adhesive, such as a thermoplastic resin or a thermosetting resin.
The conductive component may be any material as long as it is normally used as a conductive component for forming an anisotropic conductive adhesive, such as nickel.
Further, the size of the anisotropic conductive adhesive before heating and pressurization is the length in the horizontal direction as shown by the phantom line (one-dot chain line) in FIG. 2, and the length P between the opposing electrode terminals 12a. It is desirable that the length is slightly longer than the length J, and the length in the vertical direction is slightly shorter than the length J of the electrode terminal 12a.
Further, as the anisotropic conductive adhesive, any configuration such as a film shape or a paste shape may be used.

The printed wiring board 10 and the printed wiring board connection structure 100 according to the embodiment of the present invention having such a configuration have the following effects.
By providing a small volume portion R in the vicinity of the connection region S, the volume per unit length of the conductor forming the wiring 12b is smaller than the volume per unit length of the conductor forming the electrode terminal 12a. When the printed wiring board 10 and the printed wiring board 20 are subjected to thermocompression bonding via the conductive adhesive 30, the heat applied to the connection region S is transferred from the electrode terminal 12a to the wiring 12b ( Of the wiring 12b, the time for heat transfer to the wiring 12b) formed farther from the electrode terminal 12a than the small volume portion R can be effectively delayed.
Therefore, sufficient heat can be applied to the connection region S, and the conductive adhesive 30 can be sufficiently melted.
Therefore, the electrical and mechanical connection between the printed wiring board 10 and the other printed wiring board 20 can be performed satisfactorily (with sufficient connection strength) via the conductive adhesive 30. Therefore, the printed wiring board 10 and the printed wiring board connection structure 100 capable of realizing high electrical and mechanical connection reliability can be provided.
In addition, by setting the volume per unit length of the conductor constituting the small volume portion R to about 15% to 75% of the volume per unit length of the conductor constituting the electrode terminal 12a, The time during which the heat applied to the connection region S is transferred from the electrode terminal 12a to the subsequent wiring 12b rather than the small volume portion R can be more effectively delayed.
Therefore, the electrical and mechanical connection between the printed wiring board 10 and the other printed wiring board 20 can be performed more satisfactorily through the conductive adhesive 30.
Therefore, the printed wiring board 10 and the printed wiring board connection structure 100 that can realize higher electrical and mechanical high connection reliability can be obtained.
That is, as shown in FIG. 3, the printed wiring board 10 and the printed wiring board 20 melt and melt the conductive adhesive 30 by applying heat and pressure to the connection region S using the heating jig 40. Thus, the printed wiring board 100 is configured.
Therefore, in order to realize good electrical and mechanical connection between the printed wiring board 10 and the printed wiring board 20, heat that can sufficiently melt the conductive adhesive 30 and spread it over the entire connection region S. It is necessary to transfer heat to the conductive adhesive 30.
In this respect, as shown in FIGS. 2 and 3, the printed wiring board 10 according to the present embodiment is formed by copper whose electrode terminals 12 a disposed in the connection region S are conductors having high thermal conductivity. In addition, the wiring 12b extends from the electrode terminal 12a. Therefore, the heat applied to the connection region S is transferred (escapes) from the electrode terminal 12a to the wiring 12b. More specifically, the heat applied to the connection region S is transferred in the direction of the white arrow shown in FIGS. Therefore, in order to realize a good electrical and mechanical connection between the printed wiring board 10 and the printed wiring board 20, the heat transferred to the connection area S is kept in the connection area S for a certain period of time. An important point is whether or not
Here, “heat” means heat that can melt and flow the conductive adhesive 30, specifically heat of about 100 ° C. to 250 ° C., more preferably heat of about 120 ° C. to 220 ° C. It means that. This is because if the temperature is lower than 100 ° C., the adhesive force is not sufficient because it is not melted, and if it exceeds 250 ° C., the resin of the conductive adhesive 30 is thermally deteriorated and the adhesive strength is deteriorated.
The “certain time” means about 3 to 30 seconds, more preferably about 5 to 15 seconds. This is because if it is less than 3 seconds, the adhesive force is not sufficient because it is not melted, and if it exceeds 30 seconds, the resin of the conductive adhesive 30 is thermally deteriorated and the adhesive strength is deteriorated.
Therefore, by setting it as the structure which provides the small volume part R like the printed wiring board 10 which concerns on embodiment of this invention, the heat | fever loaded to the connection area | region S at the time of thermocompression bonding is from the small volume part R from the electrode terminal 12a. In addition, it is possible to effectively delay the time for heat transfer to the subsequent wiring 12b (the wiring 12b of the wiring 12b that is formed farther from the electrode terminal 12a than the small volume portion R).
Therefore, the heat applied to the connection region S can be effectively retained in the connection region S, and the conductive adhesive 30 can be sufficiently melted.
Therefore, the electrical and mechanical connection between the printed wiring board 10 and the other printed wiring board 20 can be satisfactorily performed through the conductive adhesive 30, and high electrical and mechanical connection reliability is realized. The printed wiring board 10 and the printed wiring board connection structure 100 can be obtained.
Further, the configuration of the small volume portion R is such that the length E in the short direction of the wiring 12b in plan view is shorter than the length F in the short direction of the electrode terminal 12a in plan view, and the wiring 12b and the electrode terminal 12a. In other words, the small volume portion R can be easily formed.
In addition, by using an anisotropic conductive adhesive as the conductive adhesive 30, it is possible to achieve good conductivity in the thickness direction and to achieve good insulation in the surface direction. The printed wiring board connection structure 100 can be configured.

On the other hand, in the conventional printed wiring board 1 shown in FIG. 8, the electrode terminal 2a and the wiring 2b extended from the electrode terminal 2a are made of a conductive layer formed of a conductive metal such as copper having a high thermal conductivity. Those formed by using a known forming method such as etching 2 are generally used.
Further, the volume per unit length of the conductor that forms the electrode terminal 2 a disposed in the connection region S and the unit length of the conductor that forms the wiring 2 b near the connection region S in the wiring region H. It is common to form the same volume.
Therefore, the heat applied to the connection region S during thermocompression bonding is immediately transferred from the electrode terminal 2a to the wiring 2b, so that the heat applied to the connection region S can be kept in the connection region S for a certain period of time. There was a problem that the conductive adhesive 4 could not be sufficiently melted.
Therefore, the conductive adhesive 4 cannot be sufficiently expanded in the connection region S, and the pressure bonding (adhesive force) between the printed wiring board 1 and another printed wiring board (not shown) becomes insufficient. There was a problem that good electrical and mechanical connection reliability with other printed wiring boards could not be realized.
The configuration of the conventional printed wiring board 1 is the same as the configuration of the printed wiring board 10 described above except that the small electrode portion 2a, the wiring 2b, and the insulating layer 3 are not provided with the small volume portion R. Therefore, the following detailed description will be omitted.

  Next, a printed wiring board 10 according to an embodiment of the present invention and a method for manufacturing a printed wiring board connection structure 100 using the printed wiring board 10 will be described.

First, referring to FIG. 4A, a base material layer 11 made of polyimide is prepared by a base material layer preparation step Q.
Then, referring to FIG. 4B, in the conductor layer forming step T, first, a dry film 50 is laminated on a predetermined region (region where the conductor layer 12 is not formed) on the upper surface of the base material layer 11.
And with reference to FIG.4 (c), the conductor layer 12 is formed by performing copper plating on the upper surface of the base material layer 11. FIG. Thereafter, the dry film 50 is removed.
4D, the conductive layer 12 is etched using the pattern mask 60 in the electrode terminal forming process U and the wiring forming process V, so that the electrode terminal 12a is formed in the region to be the connection region S. In the region to be the wiring region H, the wiring 12b is formed.
At this time, the volume per unit length of the conductor forming the wiring 12b forms the electrode terminal 12a in the vicinity of the connection region S in the wiring region H in the small volume portion forming step W in the wiring forming step V. A small volume portion R smaller than the volume per unit length of the conductor to be formed is formed using the pattern mask 60.
More specifically, in the vicinity of the connection region S in the wiring region H, the volume per unit length of the conductor forming the wiring 12b is larger than the volume per unit length of the conductor forming the electrode terminal 12a. It is formed as a small small volume R. More specifically, as shown in FIGS. 2 and 3, in the vicinity of the connection region S, the length E in the short direction of the wiring 12b in plan view, and the length in the short direction of the electrode terminal 12a in plan view. A small volume portion R is formed which is shorter than the length F and in which the wiring 12b and the electrode terminal 12a have the same thickness.
At this time, more preferably, the volume per unit length of the conductor constituting the small volume portion R is about 15% to 75% of the volume per unit length of the conductor constituting the electrode terminal 12a, more preferably. It is desirable to be about 20% to 50%.
Then, referring to FIG. 5A, a photosensitive cover lay 13 b is applied to the base material layer 11 and the conductor layer 12 by the insulating layer coating process X.
Then, the insulating layer 13 having the opening 13a shown in FIG. 5B is formed by exposing and developing the photosensitive cover lay 13b using a known method using the pattern mask 60.
By passing through the above process, the printed wiring board 10 which concerns on embodiment of this invention shown in FIG.5 (b) is manufactured.
Then, referring to FIG. 1, heating and pressurization are performed using a heating bar (not shown) through conductive adhesive 30 between connection area S of printed wiring board 10 and connection area S of printed wiring board 20. Thus, the printed wiring board connection structure 100 according to the embodiment of the present invention is manufactured.

The printed wiring board 10 according to the embodiment of the present invention having such a configuration and the method for manufacturing the printed wiring board connection structure 100 using the printed wiring board 10 have the following effects.
In the vicinity of the connection region S, a small volume portion R in which the volume per unit length of the conductor forming the wiring 12b is smaller than the volume per unit length of the conductor forming the electrode terminal 12a is formed. Thus, when the printed wiring board 10 and the printed wiring board 20 are thermocompression bonded, the heat applied to the connection region S is the wiring 12b following the small volume portion R from the electrode terminal 12a (of the small volume of the wiring 12b). The time for heat transfer to the wiring 12b) formed farther from the electrode terminal 12a than the portion R can be effectively delayed.
Therefore, sufficient heat can be applied to the connection region S, and the conductive adhesive 30 can be sufficiently melted.
Therefore, the electrical and mechanical connection between the printed wiring board 10 and the other printed wiring board 20 can be satisfactorily performed through the conductive adhesive 30, and high electrical and mechanical connection reliability can be realized. It can be set as the manufacturing method of the printed wiring board 10 which can be manufactured, and the connection structure 100 of a printed wiring board.
In addition, by setting the volume per unit length of the conductor constituting the small volume portion R to about 15% to 75% of the volume per unit length of the conductor constituting the electrode terminal 12a, The time during which the heat applied to the connection region S is transferred from the electrode terminal 12a to the subsequent wiring 12b rather than the small volume portion R can be more effectively delayed.
Therefore, the electrical and mechanical connection between the printed wiring board 10 and the other printed wiring board 20 can be performed more satisfactorily through the conductive adhesive 30.
Therefore, it can be set as the manufacturing method of the printed wiring board 10 and the connection structure 100 of a printed wiring board which can implement | achieve electrical and mechanical high connection reliability further.
Further, the configuration of the small volume portion R is such that the length E in the short direction of the wiring 12b in plan view is shorter than the length F in the short direction of the electrode terminal 12a in plan view, and the wiring 12b and the electrode terminal 12a. In other words, the small volume portion R can be easily formed.
In addition, by using an anisotropic conductive adhesive as the conductive adhesive 30, it is possible to achieve good conductivity in the thickness direction and to achieve good insulation in the surface direction. It can be set as the manufacturing method of the connection structure 100 of the printed wiring board which can be performed.

  Next, modified examples 1 and 2 of the printed wiring board 10 according to the embodiment of the present invention will be described with reference to FIGS. 6 and 7.

First, with reference to FIG. 6, the modification 1 of the printed wiring board 10 which concerns on embodiment of this invention is demonstrated.
With reference to FIG. 6, Modification 1 is obtained by modifying the configuration of the small volume portion R with respect to the printed wiring board 10 according to the embodiment of the present invention described above. Since the other configuration is the same as that of the printed wiring board 10 according to the embodiment of the present invention described above, the same member and the same function are given the same number, and the following detailed description is omitted. Shall.
As shown in FIG. 6, in the first modification, a configuration in which the small volume portion R is formed by forming a slit Y (through hole) in a predetermined region of the wiring 12 b (region configuring the small volume portion R). It is as.
The shape, size, number of slits Y, the interval between adjacent slits Y, the position where the slits Y are arranged, etc. are the volume per unit length of the conductor constituting the small volume portion R, and the conductor constituting the electrode terminal 12a. As long as it can be about 15% to 75% of the volume per unit length, it is not limited to that of Modification 1 and can be changed as appropriate.
Further, the slit Y can be formed using a drilling process such as drilling, etching, or laser processing.

  Thus, by forming the slit Y and forming the small volume portion R, the formation of the small volume portion R can be facilitated. Moreover, the shape (configuration) of the small volume portion R can be varied.

Next, with reference to FIG. 7, the modification 2 of the printed wiring board 10 which concerns on embodiment of this invention is demonstrated.
With reference to FIG. 7, the present modification 2 is obtained by modifying the configuration of the small volume portion R with respect to the printed wiring board 10 according to the embodiment of the present invention described above. Since the other configuration is the same as that of the printed wiring board 10 according to the embodiment of the present invention described above, the same member and the same function are given the same number, and the following detailed description is omitted. Shall.
As shown in FIG. 7, in the second modification, the thickness of the predetermined region of the wiring 12b (region where the small volume portion R is formed) is made thinner (thinner) than the thickness of the electrode terminal 12a. The small volume portion R is formed.
The thickness of the wiring 12b constituting the small volume portion R is such that the volume per unit length of the conductor constituting the small volume portion R is 15% to 75% of the volume per unit length of the conductor constituting the electrode terminal 12a. As long as it can be set to about%, it is not limited to that of the second modification, and can be changed as appropriate.
The thinning of the wiring 12b can be formed by etching.

  In this way, the predetermined region (region in which the small volume portion R is formed) of the wiring 12b is formed to be thinner (thinned) than the electrode terminal 12a to form the small volume portion R. Thus, the formation of the small volume portion R can be facilitated.

In the present embodiment, the configuration of the printed wiring board 10 is a flexible printed wiring board. However, the configuration is not necessarily limited to such a configuration, and other printed wiring boards such as a rigid flexible printed wiring board can be used. It is good also as composition to do.
In the present embodiment, the configuration of the printed wiring board 10 is a so-called single-sided printed wiring board. However, the configuration is not necessarily limited to such a configuration, and a so-called conductor layer is provided on both surfaces of the base material layer. It is good also as a structure set as a double-sided printed wiring board.
In the present embodiment, the anisotropic conductive adhesive is used as the conductive adhesive 30. However, the configuration is not necessarily limited to such a configuration, and the printed wiring board 10 and other prints are heated and pressed. Any other conductive adhesive may be used as long as it can be electrically and mechanically connected to a connected body such as a wiring board.
In addition, the configuration of the small volume portion R is not limited to that according to the present embodiment and the present modified example. Of the wiring region H, the vicinity of the connection region S is near the unit length of the conductor forming the wiring 12b. Any configuration may be used as long as the configuration can make the small volume portion R smaller in volume than the volume per unit length of the conductor forming the electrode terminal 12a.
In the present embodiment, the connected body connected to the printed wiring board 10 forming the printed wiring board connection structure 100 is the printed wiring board 20. However, the present invention is not limited to such a configuration. As long as it can connect with the connection area | region S of the printed wiring board 10 via a conductive adhesive, what kind of a to-be-connected body may be sufficient. For example, it can be an electronic component. In other words, the “printed wiring board connection structure” is not only a structure in which a plurality of printed wiring boards are connected via a conductive adhesive, but also includes a printed wiring board 10 and a connected body other than the printed wiring board. It is also a concept including those connected through a conductive adhesive.
Further, the number of electrode terminals 12a and wirings 12b, arrangement positions, and the like are not limited to those of the present embodiment, and can be changed as appropriate.

  The present invention can be used for a printed wiring board built in a mobile phone or the like.

DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Conductor layer 2a Electrode terminal 2b Wiring 3 Insulating layer 3a Opening part 4 Conductive adhesive 10 Printed wiring board 11 Base material layer 12 Conductive layer 12a Electrode terminal 12b Wiring 13 Insulating layer 13a Opening part 20 Printed wiring board 21 Base material layer 22 Conductor layer 22a Electrode terminal 22b Wiring 23 Insulating layer 30 Conductive adhesive 40 Heating jig 50 Dry film 60 Pattern mask 100 Printed wiring board connection structure E Length F Length G Length H Wiring area J Length Length K Length L Length M Length N Length P Length Q Substrate Layer Preparation Process R Small Volume Part S Connection Area S1 Outer T Conductor Layer Formation Process U Electrode Terminal Formation Process V Wiring Formation Process W Small Volume Formation Process X Insulating layer coating process Y Slit

Claims (8)

  A printed wiring board comprising at least a connection region in which electrode terminals are arranged and a wiring region in which wirings extending from the electrode terminals are arranged, and other connection regions in the connection region via a conductive adhesive What is thermocompression-bonded to the body to be connected is a unit of a conductor in which the volume per unit length of the conductor forming the wiring forms the electrode terminal in the vicinity of the connection region in the wiring region. A printed wiring board characterized by being a small volume portion smaller than the volume per length.   2. The volume per unit length of the conductor constituting the small volume portion is about 15% to 75% of the volume per unit length of the conductor constituting the electrode terminal. Printed wiring board as described in 1.   The length of the short direction of the said wiring in planar view is shorter than the length of the short direction of the said electrode terminal in planar view, The said small volume part is characterized by the above-mentioned. Printed wiring board.   The printed wiring board according to claim 1, wherein the small volume portion is formed by forming a slit in the wiring.   The printed wiring board according to claim 1, wherein the small volume portion is formed by making the thickness of the wiring thinner than the thickness of the electrode terminal.   The printed wiring board connection structure formed by connecting the printed wiring board according to any one of claims 1 to 5 to another connected body via a conductive adhesive.   The printed wiring board connection structure according to claim 6, wherein the conductive adhesive is an anisotropic conductive adhesive.   It is the manufacturing method of the printed wiring board of Claim 1, Comprising: The base material layer preparation process which prepares a base material layer, The conductor layer formation process which forms a conductor layer in the said base material layer, The said base material layer, An insulating layer covering step for covering the conductor layer with an insulating layer, and the conductor layer forming step includes at least an electrode terminal forming step for forming an electrode terminal and a wiring for forming a wiring extending from the electrode terminal. And the wiring forming step has a volume per unit length of the conductor forming the wiring is larger than a volume per unit length of the conductor forming the electrode terminal in the vicinity of the electrode terminal. A method for manufacturing a printed wiring board comprising a small volume portion forming step of forming a small volume portion.

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