JP2010251619A - Wiring board, wiring board assembly, and method of manufacturing the wiring board and the wiring board assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board and an assembly of the wiring board, capable of suppressing electrical connection of a conductor overflowing from a via hole and wiring around the via hole without increasing the size of a land. <P>SOLUTION: The wiring board includes a groove 6 formed to capture a conductor overflowing to the periphery of the via hole 4 when filling the conductor and to surround the via hole 4 within a range of a land 5. The groove 6 is formed to surround the via hole 4, thus capturing the conductor by the groove 6 and suppressing spread to the outside of the groove even if the conductor overflows in filling of the conductor into the via hole when conductive paste, namely a conductor, is pushed into the via hole 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wiring board or a wiring board joined body, and more particularly to a wiring board or a board wiring board joined body provided with a via hole having a feature in shape. The present invention also relates to a method for manufacturing such a wiring board or a wiring board assembly.

  In order to ensure electrical connection between the layers of a multilayered wiring board (hereinafter simply referred to as “multilayer board”), by providing interlayer through holes called via holes and filling the through holes with a conductor, It is common practice to ensure conduction between layers.

  As a method for filling the via hole with a conductor, a plating method for filling the via hole with a conductor using a plating technique has been widely used (for example, Patent Document 1). However, according to the plating method, if plating is performed on a via having an opening in the conductive layer on the surface of the substrate, such as a through-hole via or a blind via, plating is also performed on the periphery of the opening of the conductive layer. , The layer thickness of the conductive layer in such a portion is increased. Since it is difficult to remove the portion where the layer thickness is increased by normal etching, it is difficult to reduce the pitch between the via holes or between the via holes and another wiring more than a certain value. Therefore, when a conductor is filled by a plating method, a pitch of 40 to 50 μm is generally limited. However, as the integration degree of the wiring board increases, it is required to further reduce the pitch, that is, to increase the fann pitch.

  Therefore, in a wiring board that requires fine pitch, it is considered to use a printing method in which via holes are filled with a conductive paste, which is a paste-like conductor, using a printing technique (for example, Patent Document 2). ). According to the printing method, the thickness of the copper plating layer does not increase in the process of forming the interlayer connection unlike the plating method, and it is easy to cope with the fine pitch compared with the plating method.

JP2008-103548 JP 2001-345555 A

  By the way, in the printing method, for example, in a wiring board provided with conductive layers 102 and 103 on both surfaces of a resin layer 101 as shown in FIG. 9, the conductive paste is filled by pressing the conductive paste from the opening of the via hole 104 under pressure. It is a method to do. Therefore, in order to fill the via hole 104 with a sufficient amount of the conductive paste, it is necessary to fill the conductive paste with a slightly larger amount. Therefore, the conductive paste overflowing from the via hole 104 is deposited in an umbrella shape around the via hole. A land 105 is provided in order to prevent the umbrella-shaped conductive paste from being electrically connected to wiring around the via hole.

  However, if the land 105 is small, the conductive paste overflowing from the via hole 104 exceeds the land 105 and is electrically connected to peripheral wiring and the like. In particular, when printing is shifted, it is easy to be electrically connected to surrounding wiring. On the other hand, if the land 105 is enlarged, the gap between the via holes 104 or the gap between the via holes 104 and other electronic members has to be increased, which hinders the fine pitch.

  On the other hand, the above-mentioned Patent Document 2 overflowed by forming a via hole in a state where a peeling film was pasted in advance, and peeling off the peeling film together with the overflowing conductive paste after filling the via hole with the conductive paste. A method for removing the conductive paste is disclosed. However, not only the process of applying a peeling film and the process of peeling off increase, but also when peeling off the peeling film together with the overflowing conductive paste, there is a possibility that the conductive paste filled in the via hole may be peeled off. Cost increase and yield decrease are inevitable.

  The present invention has been made to solve such a problem, and can prevent the conductor overflowing from the via hole from being electrically connected to the wiring around the via hole without enlarging the land. An object is to provide a wiring board and a bonded body of the wiring board.

  The wiring board according to the present invention includes a plurality of conductive layers, a via hole for filling a conductor that electrically connects the plurality of conductive layers, and the via hole that overflows around the via hole when the conductor is filled. And a groove formed to surround the via hole for capturing the conductor.

  According to the above configuration, the conductor is provided with a groove formed so as to surround the via hole to capture the conductor overflowing around the via hole when the conductor is filled. Therefore, when the conductor is filled in the via hole, the conductor Even if it overflows, the conductor is trapped in this groove and does not spread out of the groove. Therefore, electrical connection between the wiring around the via hole and the conductor in the via hole can be suppressed.

  In addition, since the conductor is captured in the groove, the contact area between the conductor and the wiring board is increased, so that the adhesion between the conductor and the wiring board is improved. Therefore, it is difficult for the conductor to be detached from the wiring board, and the product yield is improved.

  The wiring board assembly according to the present invention is a wiring board assembly in which the conductive layers of the wiring board are electrically connected to each other, and is filled with a conductor in order to electrically connect the conductive layers. And a groove formed so as to surround the via hole for capturing the conductor overflowing around the via hole when the conductor is filled.

  According to the above configuration, the conductor is provided with a groove formed so as to surround the via hole to capture the conductor overflowing around the via hole when the conductor is filled. Therefore, when the conductor is filled in the via hole, the conductor Even if the liquid overflows, the conductor is trapped in this groove and does not spread out of the groove. Therefore, it is a wiring board joined body that can suppress electrical connection between the wiring around the via hole and the conductor in the via hole.

  In addition, since the conductor is captured in the groove, the contact area between the conductor and the wiring board is increased, so that the adhesion between the conductor and the wiring board is improved. For this reason, it is difficult for the conductor to be detached from the wiring board assembly, and the product yield is improved.

  In the wiring board or the wiring board assembly according to the present invention, lands are further formed around the via hole. Moreover, it is preferable that the groove is provided in the range of the land, and further includes a connection portion that divides the groove and electrically connects the via hole and the land.

  According to the above configuration, since the groove is provided in the range of the land, it is possible to prevent the conductor from oozing out of the land through the groove and conducting with other circuits. Here, the land is a concept indicating a conductive portion provided around the via hole in order to ensure electrical connection, and includes a land provided for soldering.

  In addition, since the groove further includes a connection portion that electrically connects the via hole and the land, the conductor in the via hole is electrically connected to the land via the connection portion that divides the groove. Therefore, the land can serve as a contact point.

In the wiring board or the wiring board assembly according to the present invention, it is preferable that a layer that is in contact with the surface conductive layer is exposed at the bottom of the groove.
According to the above configuration, the layer in contact with the surface conductive layer is exposed at the bottom of the groove. Since such a groove can be formed by removing the most conductive layer 2, the groove can be formed at the same time when the wiring is formed by removing a part of the conductive layer. Easy. In addition, since the groove is formed shallower than when the groove has the same depth as, for example, a via hole, gas accumulation is less likely to occur inside the groove even when the conductor flows in. Furthermore, since the insulating layer formed below the conductive layer is exposed at the bottom of the groove, when the insulating layer formed below the conductive layer is a layer having good adhesion to the conductor, The adhesion between the conductor and the wiring board is further improved. Therefore, it is difficult for the conductor to be detached from the wiring board assembly, and the product yield is further improved.

In the wiring board or the wiring board assembly according to the present invention, it is preferable that at least one of the via hole and the groove is formed by a laser beam.
According to the above configuration, since at least one of the via hole and the groove is formed by the laser beam, it can be formed in an accurate shape as compared with the case where it is formed only by etching. Moreover, when both are created by a laser beam at the same time, the number of steps can be reduced.

  In the wiring board or the wiring board assembly according to the present invention, the laser beam is preferably a laser beam formed in advance in at least one of the via hole and the groove.

  According to the above configuration, since the laser beam is a laser beam preliminarily formed in at least one shape of the via hole and the groove, the shape of at least one of the via hole and the groove is wired only by irradiating the laser beam. It can be formed on a substrate. Therefore, for example, the via hole and the groove can be easily formed as compared with the case where the via hole and the groove having the same shape are formed on the wiring substrate by using the laser beam having the irradiation surface with the dot shape.

  According to the present invention, it is possible to provide a wiring board and a bonded body of a wiring board capable of suppressing the electrical conductor overflowing from the via hole from being electrically connected to the wiring around the via hole without increasing the land. it can.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, (a) is a top view, (b) is AA sectional drawing. It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, and is drawing which shows 1 process in the manufacturing process. (A) is a top view, (b) is sectional drawing. It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, and is drawing which shows 1 process in the manufacturing process. (A) is a top view, (b) is sectional drawing. It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, and is drawing which shows 1 process in the manufacturing process. (A) is a top view, (b) is sectional drawing. It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, and is drawing which shows 1 process in the manufacturing process. (A) is a top view, (b) is sectional drawing. It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, and is drawing which shows 1 process in the manufacturing process. (A) is a top view, (b) is sectional drawing. It is drawing which shows one Embodiment of the wiring board which actualized the wiring board concerning this invention, and is sectional drawing which shows the connection state of a conductive layer. It is drawing which shows 2nd Embodiment of the wiring board assembly which actualized the wiring board assembly concerning this invention, and is sectional drawing which shows the connection state of a conductive layer. It is drawing which shows one Embodiment of the conventional wiring board, (a) is a top view, (b) is AA sectional drawing.

(First embodiment)
Hereinafter, an embodiment of a wiring board embodying the present invention will be described with reference to FIGS. The wiring board shown in FIGS. 1A and 1B is a multilayer wiring board having a conductive layer 2 and a conductive layer 3 on both surfaces of a resin layer 1 that is an insulating layer formed of a resin. The conductive layer 2 and the conductive layer 3 are electrically connected as necessary via the via hole 4 having a substantially circular cross section. A circular region called a land 5 is formed around the via hole 4 by the conductive layer 2 to improve the reliability of electrical connection. Note that a land refers to a region formed of a conductive layer for soldering in a narrow sense, but in this specification, a region formed of a conductive layer for the above purpose is broadly included including such a region. This is called land. This wiring board is characterized in that a groove 6 formed so as to surround the via hole 4 is captured within the land 5 in order to capture the conductor overflowing around the via hole 4 when the conductor is filled. Since the groove 6 is formed so as to surround the via hole 4, when the conductive paste as a conductor is pushed into the via hole 4, even when the conductor is filled in the via hole, the conductor overflows. The conductor is trapped in the groove 6 and is prevented from spreading outside the groove 6. Therefore, electrical connection between the wiring around the via hole and the conductor in the via hole can be suppressed. Further, since the groove 6 is provided within the range of the land 5, it is possible to prevent the conductor from seeping out to the outside of the land 5 through the groove 6 and conducting with other circuits.

  In addition, since the conductor is captured in the groove 6, the contact area between the conductor and the wiring board is increased, so that the adhesion between the conductor and the wiring board is improved. Therefore, it is difficult for the conductor to be detached from the wiring board, and the product yield is improved.

  Further, the groove 6 is provided in the range of the land 5, and further includes a connecting portion 10 that divides the groove 6 and electrically connects the via hole 4 and the land 5. Therefore, the conductor is electrically connected to the land 5 through this connection 10 part. Accordingly, the land 5 can serve as a contact.

A method of manufacturing a wiring board including the via hole 4 and the groove 6 will be described in detail below.
As shown in FIGS. 2A and 2B, the wiring board for forming the via hole is a multilayer board having conductive layers 2 and 3 on both surfaces of a resin layer 1 which is a non-conductive layer. Wiring is performed by partially removing the conductive layers 2 and 3 as necessary, and functions as a wiring board. In the following, for the sake of simplicity, the conductive layer 2 side in the figure is the front surface, and the conductive layer 3 side is the back surface.

  Next, as shown in FIGS. 3A and 3B, a part of the surface is removed to expose the resin layer, thereby forming lands 5 and portions to be via holes 4 and grooves 6 later. Such treatment is usually performed by etching, but may be formed by laser beam irradiation.

  As shown in FIGS. 4A and 4B, the via hole 4 and the portion of the resin layer 1 that becomes the groove 6 are removed, and the via hole 4 reaching the conductive layer 3 on the back surface is formed. Such treatment may be performed by ordinary etching or the like, but may be formed by laser beam irradiation. Thereafter, the smear residue is removed, and the surface of the conductive layer 3 exposed to the via hole 4 is made into a structure having a fine hole, and desmear treatment for improving the connection reliability of the conductive paste to be filled in a subsequent process is performed.

  As shown in FIGS. 5A and 5B, the conductive layer 7 on the front side and the conductive layer 3 on the back side are electrically joined by filling the via hole 4 after the desmear treatment with the conductive paste 7. More specifically, a conductive paste containing a conductive filler and a binder resin such as an epoxy resin is used as the conductive paste 7, and the via hole 4 is filled by a known screen printing method. Even when the conductive paste 7 overflows when the conductive paste 7 is pushed into the via hole 4, the conductor is captured in the groove 6. Since the groove 6 is provided in the land 5, the conductive paste 7 does not leak out to the outside of the land 5 and electrical contact with other wiring or the like does not occur. That is, the groove 6 prevents the conductive paste 7 from being in electrical contact with the wiring outside the via hole.

As shown in FIG. 6, a protective film 8 called a cover lay is attached to the front side and the back side through the adhesive layer 9 so that the conductive layer 2 and the conductive layer 3 are protected. The wiring board is heated and pressurized at 240 ° C. and 50 to 40 kg / cm ² . By such treatment, the conductive paste in the via hole 4 is compressed, and partly fused with the conductive layer 2 and the conductive layer 3, whereby the conductive layer 2 and the conductive layer 3 are electrically connected via the conductive paste 7. Is done. Further, since the heating and compression are performed in a vacuum atmosphere, the gas remaining in the groove 6 is sucked and replaced with the adhesive layer 9.

According to the wiring board of the above embodiment, the following effects can be obtained.
(1) In the above embodiment, since the conductive paste 7 is provided with the groove 6 formed so as to surround the via hole 4 for capturing the conductive paste 7 overflowing around the via hole when the conductive paste 7 is filled, the conductor is in the via hole. Even when the conductive paste 7 overflows when it is filled, the conductive paste 7 is captured by the groove 6 and does not spread out of the groove 6. Therefore, it is possible to suppress electrical connection between the wiring around the via hole 4 and the conductor in the via hole.

  (2) Since the contact area between the conductive paste 7 and the wiring board is increased by capturing the conductive paste 7 in the groove 6, the adhesion between the conductive paste 7 and the wiring board is improved. To do. Therefore, it becomes difficult for the conductor to be detached from the wiring substrate, and the product yield is improved.

(3) In the above embodiment, since the groove 6 is provided in the range of the land 5, the conductive paste 7 can be prevented from oozing out of the land 5 through the groove 6 and conducting with other circuits. .
(4) In the above embodiment, the conductive paste 7 in the via hole 4 divides the groove 6 and further includes the connecting portion 10 that electrically connects the via hole 4 and the land 5. 10 is electrically connected to the land 5. Accordingly, the land 5 can serve as a contact.

  (5) In the above embodiment, the resin layer 1 that is in contact with the surface conductive layer 2 is exposed at the bottom of the groove 6. Since the groove 6 can be formed by removing the conductive layer 2, the groove 6 can be formed at the same time when the wiring is formed by removing a part of the conductive layer 2. is there.

  (6) Since the groove 6 is formed shallower than when the groove 6 has the same depth as that of the via hole 4, for example, a gas pool is generated inside the groove 6 even when the conductive paste 7 flows in. Hateful. Furthermore, since the resin layer 1 formed under the conductive layer 2 is exposed at the bottom of the groove 6, the resin layer 1 formed under the conductive layer 2 has good adhesion to the conductive paste 7. In the case of a layer, the adhesion between the conductive paste 7 and the wiring board is further improved. Therefore, it is difficult for the conductor to be detached from the wiring board assembly, and the product yield is further improved.

  (7) In the above embodiment, the via hole 4 and the groove 6 may be formed by a laser beam. If the groove 6 is formed by a laser beam, it can be formed in an accurate shape as compared with the case where it is formed by etching.

(Second Embodiment)
Next, an embodiment of a bonded assembly of wiring boards embodying the present invention will be described as a second embodiment with reference to FIGS. The first embodiment is an embodiment in a wiring board, whereas the second embodiment is an embodiment in a bonded body of a wiring board, and the basic configuration is the same, and therefore the same parts are not described. Detailed description thereof is omitted.

  As shown in FIG. 7, in the first embodiment, the conductive layers 2 and 3 in the wiring board are electrically connected. On the other hand, as shown in FIG. 8, the second embodiment is an embodiment in which the present invention is applied to a joined body of wiring boards in which a plurality of wiring boards are electrically connected. In FIG. 7 and FIG. 8, the coverlay is omitted for the sake of simplicity.

  Thus, also in the second embodiment, except that the via hole 4 and the groove 6 are formed in the wiring board assembly in which the conductive layers 2, 3, 2a, 3a of the wiring board are electrically connected to each other. Since it is the same as that of the case of 1st Embodiment, the effect similar to the case of 1st Embodiment can be acquired.

In addition, you may change the said embodiment as follows.
In the above embodiment, at least one of the via hole 4 and the groove 6 may be formed by a laser beam, but a laser beam previously formed in at least one of the via hole and the groove by using a beam shaping element may be used. In this case, the shape of at least one of the via hole 4 and the groove 6 can be formed on the wiring board simply by irradiating the laser beam. Therefore, for example, the via hole 4 and the groove 6 can be easily formed as compared with the case where the via hole or the groove having the same shape is formed on the wiring substrate by using the laser beam having the pointed irradiation surface. As the beam shaping element used at this time, for example, DOE (Diffractive Optical Elements) is preferably used.

  In the above embodiment, the resin layer 1 is exposed at the bottom of the groove 6, but other configurations may be used. If it is a situation where gas accumulation is difficult to occur, it may be made deeper, or if the amount of the conductive paste overflowing is small, it may be shallower than in the above embodiment.

  In the above-described embodiment, the groove 6 is divided and the connection portion 10 that electrically connects the via hole 4 and the land 5 is provided, but other configurations may be used. If the conductive paste 7 in the via hole 4 does not need to be electrically connected to the land 5 via the connecting portion 10 that divides the groove 6, the connecting portion 10 is omitted, so that the groove 6 is further formed. Can be easy.

  -In the said embodiment, there is no restriction | limiting in particular in the material of a wiring board. For example, it may be difficult to deform such as a glass substrate or a hard resin substrate, or may be flexible such as a soft resin substrate.

  Similarly, in the wiring board assembly, there is no particular limitation on the material of the wiring board to be configured. For example, wiring substrates that are difficult to deform, such as glass substrates and hard resin substrates, may be joined together, or flexible wiring substrates, such as soft resin substrates, that are joined together. Also good. Moreover, what joined the wiring board which cannot change easily, and the flexible wiring board may be used.

In the above embodiment, the wiring board assembly is obtained by joining two wiring boards, but may have other configurations. That is, three or more wiring board assemblies may be used.
In the above embodiment, the wiring board is a three-layer board having the conductive layers 2 and 3 on the front side and the back side with the resin layer 1 interposed therebetween, but may be a multilayer board having three or more layers. In such a case, the depths of the via holes 4 and the grooves 6 also differ depending on the conductive layers to be electrically joined.

  Similarly, the wiring board constituting the wiring board assembly may be a wiring board having one conductive layer or a multilayer board having two or more layers. In the case of a multilayer substrate, the depths of the via holes 4 and the grooves 6 also differ depending on the conductive layer to be electrically connected.

  The present invention relates to a wiring board or a wiring board joined body, and more particularly to a wiring base or a board wiring board joined body provided with a via hole having a feature in shape. The present invention also relates to a method for manufacturing such a wiring board or a wiring board assembly. Therefore, it can be widely used for electric devices including a wiring board.

  DESCRIPTION OF SYMBOLS 1 ... Resin layer (insulating layer) 2, 2a, 3, 3a ... Conductive layer, 4 ... Via hole, 5 ... Land, 6 ... Groove, 7 ... Conductive paste (conductor), 8 ... Protective film, 9 ... Adhesion Layer 10, connection portion 101, resin layer 102, 103 conductive layer 104 via hole 105 land

Claims (6)

A plurality of conductive layers electrically isolated from each other by an insulating layer;
A via hole for filling the inside with a conductor electrically connecting the plurality of conductive layers;
A wiring board comprising: a groove formed so as to surround the via hole for capturing the conductor overflowing around the via hole when the conductor is filled. The conductive layer provided in each of the plurality of wiring boards is a wiring board assembly electrically connected to each other,
In order to electrically connect the conductive layers to each other, a via hole for filling a conductor inside,
A wiring board joined body comprising a groove formed so as to surround the via hole for capturing the conductor overflowing around the via hole when the conductor is filled. A land is further formed around the via hole,
The groove is provided within the land;
3. The wiring board according to claim 1, further comprising a connection part that divides the groove and electrically connects the via hole and the land. 4.   The wiring board or the wiring board joined body according to any one of claims 1 to 3, wherein a layer in contact with the surface conductive layer is exposed at a bottom of the groove.   5. The method of manufacturing a wiring board or a wiring board assembly according to claim 1, wherein at least one of the via hole and the groove is created by a laser beam.   6. The method of manufacturing a wiring board or a wiring board assembly according to claim 5, wherein the laser beam is a laser beam previously formed in at least one of the via hole and the groove.

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