JP2010045155A - Multilayer laminated circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer laminated circuit board hardly causing the breaking of a wire of a metal circuit. <P>SOLUTION: The multilayer laminated circuit board 1 is a multilayer laminated circuit board including a lamination structure of alternately laminating a resin film 100 and a circuit layer 200. The board is characterized in that the resin film 100 has one or more multi-conduction parts 110, the multi-conduction part 110 occupies an area with a diameter of ≥10 μm and ≤3000 μm and has two or more conduction vias 120, and the conduction via 120 has an inner diameter of ≥5 μm and ≤300 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer laminated circuit board, and more particularly to a multilayer laminated circuit board in which disconnection of a metal circuit is unlikely to occur.

  Products around us, such as electrical products, electronic products, semiconductor products, antenna circuit boards, IC cards, robots, etc., are all popular in small products that do not take up space, and the appearance of smaller products Is expected. In order to meet the needs of such products, technological development of product miniaturization has been advanced from both the approach of downsizing the outer shape of the product and the approach of downsizing the inside of the product. However, it is said that the miniaturization of the product by the approach of miniaturizing the outer shape of the product is already close to the limit, and the miniaturization inside the product has come to be expected.

  Under such circumstances, as an approach for downsizing the interior of a product, a method of making a circuit board used in the product a light, thin and small circuit structure has attracted particular attention in recent years. Conventional circuit boards have been studied to reduce the size of a circuit board by forming one or two layers of circuits on a plane and miniaturizing the circuit itself. Since miniaturization alone has limited miniaturization, multilayer laminated circuit boards that form a three-dimensional circuit by multilayering circuit boards have been studied.

  Such a multilayer laminated circuit board is generally manufactured by a build-up method. In the build-up method, the conductive layer formed on the insulating resin film is partially removed by etching to form a metal circuit, and an adhesive is applied on the metal circuit. A resin film on which a conductive layer is formed is bonded. Thereafter, a conductive via is formed in the conductive portion of the bonded resin film, and the conductive via is filled with plating or paste. Then, by etching the conductive layer of the bonded resin film, it is partially removed to form a metal circuit. Thereafter, these steps are repeated to make the metal circuit multilayer. However, the multilayer laminated circuit board formed by this build-up method has a problem that disconnection occurs in the metal circuit when heat is applied to itself.

  Various attempts have been made in Patent Documents 1 to 6 in order to solve these problems, but the above-described problems have not been sufficiently solved in any multilayered circuit board. Below, the outline of the multilayer laminated circuit board shown by patent documents 1-6 is explained.

  The multilayer laminated circuit board of Patent Document 1 uses a low-melting-point solder that does not contain lead to connect two-layer resin film metal circuits, thereby increasing the bonding strength between the resin films and preventing disconnection of the metal circuits. It is what. However, when this multilayer laminated circuit board is heated, the low melting point solder is remelted, and the metal circuit is disconnected.

  In Patent Document 2, the conductive vias opened so as to penetrate from the metal circuit on the front surface side to the metal circuit on the back surface side are filled with solder, thereby increasing the bonding strength between the flexible substrate and the reinforcing substrate, Although it is described that the disconnection of the metal circuit is prevented, the disconnection of the metal circuit is likely to occur when heat is applied as in Patent Document 1.

  Patent Document 3 describes a multilayer laminated circuit board in which resin films are bonded together by bumps. However, since it is difficult to reduce the diameter of the bump, there is a problem that it is not possible to cope with downsizing of the multilayer laminated circuit board.

  Patent Document 4 discloses a multilayer laminated circuit board in which conductive vias are filled in conductive vias of the multilayer laminated circuit board. However, there is a concern that the metal circuit may be disconnected due to heat when conducting for a long period of time. Was left.

  In Patent Document 5, the adhesion between the front and back resin films is enhanced by filling the conductive vias in the conductive vias when laminating the resin films. However, the adhesion between the conductive paste and the resin film is sufficient. I couldn't.

Furthermore, Patent Document 6 describes a multilayer laminated circuit board that prevents misalignment between laminated resin films by using an adhesive for bonding resin films, but only prevents misalignment. However, it could not be said that the disconnection of the metal circuit could be sufficiently prevented.
JP 2005-243911 A Japanese Patent Laid-Open No. 2007-266481 Japanese Patent Laid-Open No. 2008-60582 JP 2007-335631 A Japanese Patent Laying-Open No. 2005-223010 JP 2008-91439 A

  As described above, Patent Documents 1 to 6 all provide a multilayer laminated circuit board in which disconnection of a metal circuit is unlikely to occur by improving an adhesive means or an adhesive material between resin films.

  However, since any multilayer laminated circuit board has a conductive portion formed by one conductive via, if heat is applied to itself, the thermal expansion coefficient of the resin film and the thermal expansion of the metal circuit in the conductive via Since the coefficients are different from each other, there is a common problem that the metal circuit in the conductive via is subjected to compression or tensile stress due to the difference in thermal expansion, and the metal circuit in the conductive via is disconnected.

  As another problem, for example, when heat is applied to the multilayer laminated circuit board, a difference in expansion occurs in each resin film depending on the distance from the heat source in the plurality of resin films included in the multilayer laminated circuit board, and the multilayer laminated circuit board Is distorted, stress is applied to the metal circuit in the conductive via formed in the resin film, and the metal circuit is disconnected. The present invention has been made in view of the above situation, and an object of the present invention is to provide a multilayer laminated circuit board in which disconnection of a metal circuit is unlikely to occur.

  The multilayer laminated circuit board of the present invention is a multilayer laminated circuit board including a laminated structure in which a resin film and a circuit layer are alternately laminated, and the resin film has one or more multi-conductive portions, The multi-conductive portion occupies a region having a diameter of 10 μm or more and 3000 μm or less and has two or more conductive vias, and the conductive via has an inner diameter of 5 μm or more and 300 μm or less.

  Further, when the thickness of the resin film is T and the inner diameter of the conductive via is d, it is preferable that 0 <d / T ≦ 60.

Moreover, it is preferable to process and use the long resin film.
Further, the present invention is a component or product using a multilayer laminated circuit board.

  The product is preferably one of an electrical product, an electronic product, a semiconductor product, an antenna circuit board, an IC card, a solar cell, an automobile, or a robot.

  The multilayer laminated circuit board of the present invention has an effect that the disconnection of the metal circuit is hardly caused by having the above-described configurations.

<Multilayer laminated circuit board>
The multilayer laminated circuit board of the present invention will be described below with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an example of a multilayer laminated circuit board of the present invention. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

  The multilayer laminated circuit board 1 of the present invention includes a laminated structure in which resin films 100 and circuit layers 200 are alternately laminated, as shown in FIG. 1 shows a structure in which three layers of resin films 100 are laminated, the minimum number of layers in the laminated structure in the present invention is that in which two layers of resin films 100 are laminated. In this case, the number of stacked circuit layers 200 can be two or three. On the other hand, the maximum number of laminated layers in the laminated structure in the present invention is not particularly limited and can be laminated according to the use, but generally, the resin film 100 is generally laminated by about 2 to 30 layers.

  Here, the resin film 100 of the multilayer laminated circuit board 1 of the present invention has one or more multi-conductive portions 110, and the multi-conductive portions 110 include two or more conductive vias 120 penetrating the front and back of the resin film. It is characterized by providing. Thus, by providing two or more conductive vias 120 penetrating the front and back of the resin film 100, it is possible to make it difficult to cause disconnection of the metal circuit. Hereinafter, each component included in the multilayer laminated circuit board of the present invention will be described.

<Resin film>
The multilayer laminated circuit board of the present invention includes two or more resin films. These resin films are made of an insulating material, and any conventionally known resin film used for this type of application can be used. As such a resin film, for example, a resin film such as polyimide (PI), acrylic, liquid crystal polymer (LCP), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN) can be used.

  Such a resin film 100 is preferably used by processing a long one. As such a long resin film, for example, those having a length of about 1 to 10000 m are preferable, and those having a length of about 100 to 3000 m are more preferable. By using a long one, continuous processing can be performed, and production efficiency can be improved. If it is less than 1 m, it is difficult to use it in the form of a roll, and the processing efficiency is not preferable. If it exceeds 10000 m, continuous processing may be hindered in the formation of the underlayer described later, which is preferable. Absent.

  The “long film” of the resin film has a length as described above and is suitable for use as a roll wound shape. Even if it is less than that, it is intended to include those that can be handled as a long one by bonding a plurality of single-layer resin films.

  Moreover, it is preferable that the thickness of the resin film 100 is 3 micrometers or more and 200 micrometers or less. If the thickness of the resin film 100 is less than 3 μm, the workability is too bad, which is not preferable. If the thickness is more than 200 μm, the conductive via 120 becomes difficult to process, which is not preferable.

<Circuit layer>
The circuit layer 200 formed on the resin film 100 of the present invention includes a metal circuit 50. Further, portions other than the metal circuit 50 of the circuit layer 200 may be filled with an insulating adhesive resin 70, and the resin films 100 can be attached to each other via the adhesive resin 70. As described above, the circuit layer 200 of the present invention may be configured only by the metal circuit 50 or may be configured by the metal circuit 50 and the adhesive resin 70.

<Metal circuit>
The metal circuit 50 includes a plating layer 140, and may further include a base layer 130 between the plating layer 140 and the resin film 100. In the present invention, the base layer 130 and the plating layer 140 formed in the conductive via 120 may also be referred to as the metal circuit 50 for convenience.

  Here, the underlayer 130 functions to improve the adhesion between the plating layer 140 and the resin film 100 and may be formed of one layer or two or more layers. When the underlayer 130 is formed of two or more layers, it is preferable to include an antioxidant layer and an underlayer metal layer. Such a base layer may be formed by any method, but can be formed by, for example, electroless plating, vapor deposition, sputtering, or the like. In particular, it is preferable to form by sputtering from the viewpoint of accurately controlling the film thickness.

  This antioxidant layer is preferably composed of at least one metal selected from the group consisting of Ni, Cr, Ti, Co and Si, or an alloy containing at least one of the metals. 20 nm is preferable.

  Further, the base metal layer is preferably formed on the antioxidant layer, and at least one metal selected from the group consisting of Cu, Au, Ag, Sn, Ni, Bi and Zn or at least one of the metals is used. It is preferable to use a seed-containing alloy. The layer thickness of the base metal layer is preferably about 50 to 500 nm.

  The plating layer 140 is a layer formed by electroplating, and is at least one metal selected from the group consisting of Cu, Au, Ag, Sn, Ni, Bi, and Zn, or at least one of the metals. It is preferable to comprise by the alloy containing, and it is more preferable to comprise by Cu or the alloy containing Cu. When forming the above-described base metal layer, it is preferable to use the same material for the base metal layer and the plating layer 140.

<Adhesive resin>
Any adhesive resin 70 may be used as long as the resin films 100 used for the multilayer laminated circuit board can be attached to each other. For example, an epoxy resin or an acrylic resin can be used. Resin, polyimide resin, and the like can be used.

<Multi conduction part>
Each resin film 100 constituting the multilayer laminated circuit board 1 of the present invention has one or more multi-conductive portions 110, and two or more conductive vias 120 are provided in the multi-conductive portions. Here, the multi-conducting portion is a conductive via that is formed at a site where conduction of the metal circuit on both the front and back sides of the resin film is desired due to the configuration of the metal circuit, and penetrates the front and back of the resin film. By forming two or more, the conduction between the front and back sides is ensured.

  And the said multi conduction | electrical_connection part means all the several conduction | electrical_connection vias formed in close proximity to the desired site | part, and says the cylindrical area | region where the cross-sectional area becomes the minimum, The said cross-sectional area is on a resin film. It is preferable to occupy a region having a diameter of 10 μm or more and 3000 μm or less. That is, for example, as shown in FIG. 2, when there are three conductive vias 120 that are closely related, a region that includes all three conductive vias and that has the smallest cross-sectional area of the cylindrical region is defined as a multi-region. It is referred to as a conduction part 110.

  As described above, the diameter of the multi-conductive portion is preferably 10 μm or more and 3000 μm or less. If the diameter of the multi-conductive portion is less than 10 μm, the conduction of the metal circuit formed on the front and back of the resin film may not be sufficiently ensured. If the diameter exceeds 3000 μm, the area occupied by the metal circuit itself becomes excessive, and the expected result It will be against the purpose.

  In this way, by providing two or more conductive vias in the multi-conductive portion, it is applied to the metal circuit in the conductive via due to the difference in thermal expansion coefficient between the resin film and the metal circuit in the conductive via when heat is applied. Compressive or tensile stress can be distributed to each of these conductive vias, and disconnection of the metal circuit can be suppressed.

  In addition, if two or more conductive vias are provided in this way, even if a disconnection of a metal circuit occurs in one conductive via, conduction is maintained by another conductive via. There is also an effect that the formed metal circuit is not completely disconnected.

  Furthermore, compared to the case where only one conductive via is formed as in the prior art, the inner diameter of the conductive via can be reduced, thereby further reducing the influence of compressive or tensile stress on the metal circuit in the conductive via. There is also an effect that can be done. According to the present invention, the disconnection of the metal circuit can be remarkably suppressed by the synergistic effect of these actions.

<Conduction vias>
The conductive via 120 included in the multi-conductive portion 110 of the present invention is a hole provided so as to penetrate the front and back of the resin film 100, and the metal on the front and back of the resin film 100 is formed by forming a metal circuit in the conductive via. The circuit can be conducted.

  Here, forming a metal circuit in a conductive via means that a metal circuit is formed on the inner wall surface of the conductive via, and the metal circuit formed in this way is formed so as to fill the entire conductive via. Alternatively, it may be formed in a through hole shape so that a cavity remains in the conductive via.

  In addition, it is preferable to increase the inner diameter of the conductive via from the viewpoint of ensuring the conduction of the metal circuit on the front and back sides of the resin film. However, as the inner diameter is increased, the conductive via is more heated when heat is applied as described above. Since the compressive or tensile stress applied to the inner metal circuit is concentrated, disconnection of the metal circuit is likely to occur.

Therefore, the conductive via has an inner diameter of 5 μm or more and 300 μm or less, more preferably an inner diameter of 10 μm or more and 50 μm or less, and further preferably an inner diameter of 15 μm or more and 20 μm or less. Further, from the viewpoint of preventing disconnection of the conductive via when heat is applied, the cross section is preferably 0.2 mm ² or less.

  If the inner diameter of the conductive via is larger than 300 μm, the metal circuit in the conductive via is likely to be disconnected for the reasons described above, which is not preferable. In addition, if the inner diameter of the conductive via is smaller than 5 μm, it becomes difficult to process the conductive via, and it is difficult for the plating solution to enter the conductive via when electroplating to form a plating layer on the conductive via. Is also not preferred.

  The number of conductive vias 120 to be formed is preferably about 2 to 7 and more preferably about 3 to 5 with respect to one multi-conductive portion. On the other hand, as described above, it is not preferable to form only one conductive via for one conductive portion because the metal circuit is easily disconnected for the reasons described above. In addition, it is not preferable to form eight or more conductive vias in that the area of the multi-conductive portion becomes too large, and it is not preferable in that the processing time of the conductive via becomes long and the cost increases.

  Regarding the relationship between the inner diameter of the conductive via and the number of conductive vias included in the multi-conductive portion, for example, when the inner diameter of the conductive via is 5 μm or more and less than 50 μm, it is preferable to form two to seven conductive vias. Is preferably 50 μm or more and 300 μm or less, it is preferable to form two or three conductive vias.

  However, in the case where the size of the conductive via is unavoidably large due to its structure, the conductive portion is formed with a single conductive via instead of the multi-conductive portion only in that portion. May be. However, from the viewpoint of avoiding disconnection of the metal circuit due to thermal stress, it is needless to say that it is preferable to provide as many conductive vias as possible within the above-described range for one multi-conductive portion.

  Further, when the thickness of the resin film is T and the inner diameter of the conductive via is d, 0 <d / T ≦ 60 is preferable, and 0.01 ≦ d / T ≦ 6 is more preferable. Preferably, 0.3 ≦ d / T ≦ 2 is more preferable. Thus, by controlling the value of d / T within a specific numerical range, disconnection of the metal circuit in the conductive via due to thermal stress can be extremely effectively prevented. If the value of d / T is larger than 60, the inner diameter of the conductive via is too large with respect to the thickness of the resin film, so that when heat is applied, the compression or tensile stress applied to the metal circuit in the conductive via is increased. Since it becomes too large and the metal circuit in the conductive via is easily disconnected, it is not preferable.

<Coefficient of thermal expansion of resin film>
The thermal expansion coefficient of the resin film used for the multilayer laminated circuit board of the present invention is preferably 1 ppm / ° C. or more and 300 ppm / ° C. or less, more preferably 2 ppm / ° C. or more and 200 ppm / ° C. or less, and more preferably 3 ppm / ° C. or more and 150 ppm / ° C. or less. Further preferred. If the thermal expansion coefficient of the resin film is less than 1 ppm / ° C., the resin film becomes brittle, which is not preferable. If it exceeds 300 ppm / ° C., the multilayer film circuit board is distorted due to expansion of the resin film when heat is applied. This is not preferable because stress is applied to the metal circuit in the conductive via and the metal circuit is easily disconnected. Here, in this invention, a thermal expansion coefficient shall mean the thermal expansion coefficient of the orthogonal | vertical direction (namely, longitudinal direction) with respect to the width direction of a resin film.

  In addition, it is preferable to use a resin film having a large coefficient of thermal expansion for the easily distorted portion of the multilayer laminated circuit board, and it is preferable to increase the thickness of the resin film.

  Moreover, it is preferable that the thermal expansion coefficient of the resin film of any one layer among the resin films contained in the multilayer laminated circuit board of this invention differs from the thermal expansion coefficient of at least one other resin film. Thus, by using a resin film having a thermal expansion coefficient different from that of other resin films for at least one resin film, the difference in expansion caused by the distance from the heat source between these resin films can be reduced. Thus, disconnection of the metal circuit in the conductive via can be suppressed.

<Usage of multilayer multilayer circuit board>
For example, as shown in FIG. 3, the multilayer laminated circuit board of the present invention has a metal circuit 50 and a rigid board 301 on the lowermost surface of the multilayer laminated circuit board attached by an adhesive metal 401 to form an outermost layer of the multilayer laminated circuit board. The metal circuit 50 on the upper surface and the Si substrate 302 can be used as a configuration in which the adhesion metal 402 is attached. In this case, it is preferable that both the adhesive metal 401 and the adhesion metal 402 are formed by solder. However, the adhesion metal 402 is not limited to the formation by solder, but is formed by bonding or a combination of a stat pin and a bump. May be. The Si substrate 302 may be a rigid substrate or a copper substrate, and the rigid substrate 301 may be an Si substrate or a copper substrate. Further, from the viewpoint of preventing these cuts when heat is applied, the cross section of the adhesive metal 401 and the adhesive metal 402 is preferably 0.2 mm ² or less.

  In the case of using such a multilayer laminated circuit board, the uppermost Si substrate 302 has a small coefficient of thermal expansion, and the lowermost rigid substrate 301 has a large coefficient of thermal expansion. The thermal expansion coefficient is preferably selected so that the thermal expansion coefficient is smaller for the resin film on the Si substrate 302 side and the thermal expansion coefficient is larger for the resin film on the rigid substrate 301 side.

  More specifically, the thermal expansion coefficient of the resin film laminated near the Si substrate 302 is preferably 2 ppm / ° C. or more and 10 ppm / ° C. or less, and more preferably 3 ppm / ° C. or more and 5 ppm / ° C. or less. When the thermal expansion coefficient is less than 2 ppm / ° C., the multilayer laminated circuit board becomes too fragile and difficult to handle, and when the thermal expansion coefficient exceeds 10 ppm / ° C., it is not preferable. This is not preferable because the difference between the coefficient of thermal expansion and the thermal expansion coefficient of the multi-layer laminated circuit board is so great that the multilayer laminated circuit board is distorted and the metal circuit in the conductive via is easily disconnected.

  In addition, it is preferable to use a material having a thermal expansion coefficient close to that of the rigid substrate 301 as the thermal expansion coefficient of the resin film laminated near the rigid substrate 301. Further, when the rigid substrate is bent, it is preferable to use a resin film that can cope with the bending. In addition, when a copper substrate is used as one or both of the Si substrate and the rigid substrate, the thermal expansion coefficient of the resin film laminated near the copper substrate is the thermal expansion coefficient (16.8 ppm / It is preferable to use a material close to [° C.], and the value is preferably from 10 ppm / ° C. to 20 ppm / ° C., more preferably from 15 ppm / ° C. to 18 ppm / ° C.

<Parts or products>
The multilayer laminated circuit board of the present invention is used for general components or products. Examples of the product include an electric product, an electronic product, a semiconductor product, an antenna circuit board, an IC card, a solar cell, an automobile, and a robot.

<Manufacturing method of multilayer multilayer circuit board>
In the production of the multilayer laminated circuit board of the present invention, first, two or more conductive vias 120 penetrating the front and back are formed in each multi-conductive portion of the resin film 100, and then the entire surface of the resin film 100 (inside the conductive vias) The base layer 130 is formed over the wall (including the wall surface), and the plating layer 140 is formed thereon by electroplating.

  Thereafter, a part of the base layer 130 and the plating layer 140 is removed to form the metal circuit 50, and another resin film 100 is attached with the adhesive resin 70. Subsequently, two or more conductive vias are formed at the position of the multi conductive portion of the newly attached resin film 100, and then a metal circuit is formed in the same manner as described above. The multilayer laminated circuit board of the present invention is manufactured by continuously repeating the above operation using a long resin film.

  If the metal circuit 50 is formed of a plating layer formed by electroplating as described above, it is preferable that disconnection hardly occurs in the metal circuit in the conductive via, and cost increase can be suppressed even if the resin film is multilayered.

  Note that the metal circuit 50 of the multilayer laminated circuit board 1 of the present invention may be formed by, for example, any one of an etching method and a semi-additive method. In the etching method, a metal layer is formed by forming a plating layer on the entire surface of the resin film (including the inner wall surface of the conductive via) by electroplating, and then removing the plating layer and the underlayer which become unnecessary portions by etching. It is a method of forming.

  On the other hand, in the semi-additive method, a portion of the resin film surface (including the inner wall surface of the conductive via) that is not a circuit is masked with a resist, and then a plating layer having a required thickness is formed by electroplating. The metal circuit is formed by peeling the film.

  In the following, a method for manufacturing a multilayer laminated circuit board will be described by taking a semi-additive method as an example of a method for forming a metal circuit. The manufacturing method repeats a conductive via formation process, an underlayer formation process, a resist formation process, an exposure process, a development process, an activation process, a plating layer formation process, a resist peeling process, a soft etching process, and a resin film lamination process in this order. This is a method of manufacturing a multilayer laminated circuit board. These steps will be described below.

<Conductive via formation process>
First, three conductive vias 120 are formed on the resin film 100 so as to form a multi-conductive portion (FIG. 4). Here, any device can be used as long as it can adjust the formation of the conductive via so that the depth of the conductive via is equal to the thickness of the resin film, but from the viewpoint that the conductive via can be formed with a small diameter and at a low cost. It is preferable to use a UV-YAG laser.

<Underlayer formation process>
Next, after pre-treating the surface of the resin film 100 (including the inner wall surface of the conductive via) with an ion gun, an antioxidant layer is formed on the surface of the resin film 100 (including the inner wall surface of the conductive via). By further forming a base metal layer thereon, the base layer 130 can be formed (FIG. 5). The antioxidant layer and the base metal layer included in the base layer 130 can be formed by, for example, electroless plating, vapor deposition, sputtering, or the like. In addition, either one or both of the antioxidant layer and the base metal layer may not be formed.

<Resist formation process>
Through the above process, the surface of the base layer 130 formed on the resin film 100 is washed with an acid to activate the surface of the base metal layer included in the base layer 130, and then a resist is formed (not shown). This resist may be formed by a method of bonding a dry film obtained by forming a resist film, or by a method of applying a resist ink.

  The method of laminating a dry film is suitable for low-volume production, so it can handle a wide variety of products, and it is excellent in that the laminating process is not complicated, but the manufacturing cost is high. Have a problem.

  On the other hand, the method of applying a resist ink is excellent in that the manufacturing cost can be reduced because it is suitable for mass production, but has a problem that the application process becomes complicated. Below, the formation of the resist by the method of bonding a dry film is demonstrated.

  First, the resin film 100 on which the base layer 130 shown in FIG. 5 is formed is set on the delivery shaft of the laminate winding device, the tip of the resin film 100 is set on the winding shaft, and then the base layer of the resin film 100 is set. Winding is performed by rotating the winding shaft while attaching a dry film on 130. Thus, a dry film is affixed on the resin film 100, and a resist is formed on the base layer of the resin film (not shown).

The temperature at the time of laminating is preferably 30 to 150 ° C, more preferably 60 to 110 ° C. The pressure at the time of lamination is preferably 0.3~5kg / cm ^2, more preferably 2-3 kg / cm ^2. Moreover, the line speed at the time of winding the laminated resin film is preferably 0.1 to 10 m / min, and more preferably 0.5 to 3 m / min.

<Exposure process>
Next, a mask corresponding to a desired metal circuit pattern is overlaid on the resin film on which the resist is formed as described above, and then UV exposure is performed to expose a portion not covered with the mask. Here, the portion covered with the mask is removed in the next development step, and a metal layer is formed by forming a plating layer in a plating layer forming step described later.

  The exposure apparatus used for this exposure may be a parallel light exposure apparatus or a direct exposure apparatus. However, it is preferable to use a parallel light exposure apparatus from the viewpoint of forming a fine circuit, and it is preferable to use a direct exposure apparatus from the viewpoint that the exposure position can be adjusted corresponding to the shrinkage of the resin film. .

<Development process>
Next, the portion of the resist 170 covered with the mask in the above exposure process is developed with a weak alkaline solution. Thereby, the resin film 100 in which the resist 170 as shown in FIG. 6 is formed can be obtained. It is preferable to use sodium carbonate or an amine-based material for the weak alkaline solution used for development. Further, the pH of the weak alkaline solution is preferably 7 or more and 13 or less, and more preferably 8.5 or more and 10.0 or less. If the pH of the weak alkaline solution is less than 7, the resist is not removed, which is not preferable. If the pH is higher than 13, the resist 170 in the portion not covered with the mask in the exposure process is also all peeled off.

  Moreover, it is preferable that the temperature of a weak alkali solution is 10-70 degreeC, and it is more preferable that it is 20-35 degreeC. If the temperature of the weak alkaline solution is lower than 10 ° C., the resist 170 is not removed, which is not preferable. If the temperature of the weak alkaline solution is higher than 70 ° C., the UV-exposed portion of the resist 170 is also peeled off. The development processing time varies depending on the type of resist and cannot be defined uniformly, but it is usually preferably about 20 seconds to 300 seconds.

<Activation process>
Next, the surface of the underlying layer 130 (underlying metal layer) on the developed resin film 100 is activated with an acid-based solution. Thereby, the adhesion defect of a plating layer and a base layer (base metal layer) can be prevented. The acid solution used for the activation may be any acid solution as long as it shows acidity, but HCl, H ₂ SO ₄ , ammonium persulfate, etc. should be used from the viewpoint of activation at low cost. Is preferred.

  Moreover, it is preferable that the density | concentration of the acid contained in an acid system solution is 0.5-20 mass%, and it is more preferable that it is 3-10 mass%. If the concentration of the acid-based solution is lower than 0.5% by mass, it is not preferable because the surface of the underlayer (underlying metal layer) is difficult to activate. If the concentration of the acid-based solution is higher than 20% by mass, the underlayer is not preferred. This is not preferable because there is a possibility that abnormality may occur on the surface of the (underlying metal layer).

  Moreover, it is preferable that the temperature of the acid-type solution at the time of activation is 10-70 degreeC, and it is more preferable that it is 30-50 degreeC. When the temperature of the acid solution is lower than 10 ° C., it is not preferable because it takes too much time to activate the underlayer, and when the temperature of the acid solution is higher than 70 ° C., environmental problems occur, which is not preferable. . Further, since the treatment time varies depending on the surface state of the underlayer (underlying metal layer), it cannot be uniformly defined, but is usually preferably about 3 seconds to 300 seconds.

<Plating layer formation process>
Next, a plating layer 140 as shown in FIG. 7 is formed by electroplating on the base layer 130 activated as described above. The plating solution used for this electroplating may be any acidic solution containing a metal that forms the plating layer, but sulfuric acid is used from the viewpoint that the plating solution itself is stable and can be plated at a low cost. Copper, copper pyrophosphate and the like are preferably used. In addition, when using copper sulfate for a plating solution, it is preferable that the density | concentration of copper sulfate is 30-300 g / l, and it is more preferable that it is 70-150 g / l. Moreover, it is preferable that the chloride ion concentration of this plating solution is 10-100 ppm, and it is more preferable that it is 40-70 ppm.

  Moreover, it is preferable to use a sulfuric acid as an acidic solution used for a plating solution, and when using a sulfuric acid, it is preferable that the density | concentration of a sulfuric acid is 50-300 g / l, and it is more preferable that it is 80-200 g / l. .

Also, the current density at the time of electroplating is preferably 0.1 to 10 A / dm ^2, and more preferably 0.5~4A / dm ^2. Moreover, 20-60 degreeC is preferable and the temperature of the plating solution at the time of electroplating has more preferable 30-40 degreeC. The plating time varies depending on the thickness of the plating layer and cannot be defined uniformly, but it is usually preferably about 600 seconds or more and 6000 seconds or less.

<Resist stripping process>
Next, after the metal circuit is formed by the above-described plating layer forming step, the resist is peeled off using an alkaline solution. The alkali solution used for resist stripping may be any solution as long as it shows alkalinity, but from the viewpoint of the stability of the alkali solution itself and the cost of the alkali solution, use a sodium hydroxide or alcohol-based solution. Is preferred.

  Moreover, when using sodium hydroxide for an alkali liquid, it is preferable that the density | concentration of sodium hydroxide is 0.1-50 mass%, and it is more preferable that it is 1-10 mass%. Moreover, it is preferable that the temperature of the alkaline solution used for resist peeling is 30-90 degreeC, and it is more preferable that it is 50-70 degreeC. Note that the resist stripping time varies depending on the stripped state of the resist, and cannot be defined uniformly, but it is usually preferably about 20 seconds to 120 seconds.

<Soft etching process>
Next, the resin layer on which the metal circuit 50 as shown in FIG. 8 is formed is obtained by peeling and removing the base layer 130 by soft etching. Any chemical may be used for the peeling of the base metal layer included in the base layer, but ammonium persulfate is preferably used from the viewpoint of low cost. When using this ammonium persulfate, the concentration of ammonium persulfate is preferably 1 to 20%, more preferably 5 to 10%.

  Moreover, it is preferable that the process temperature when carrying out soft etching of the base metal layer is 20-60 degreeC, and it is more preferable that it is 30-40 degreeC. It should be noted that the time required for the soft etching peeling depends on the thickness of the underlying metal layer, the concentration of the chemical, and the temperature, and thus cannot be defined uniformly, but is usually preferably about 30 seconds to 200 seconds.

  Moreover, as a chemical | medical agent used for peeling of an antioxidant layer, it is preferable to use nickel chromium peeling liquid (brand name: NC (made by Nippon Chemical Industry Co., Ltd.)). Moreover, when using this chemical | medical agent, it is preferable that the density | concentration of this chemical | medical agent is 60 to 100%. If the concentration of this chemical is lower than 60%, it takes a long time for peeling, which is not preferable.

  Moreover, it is preferable that the process temperature when carrying out soft etching of the antioxidant layer is 35-55 degreeC. It should be noted that since the time required for the soft etching peeling depends on the thickness of the antioxidant layer, the concentration of the chemical and the temperature, it cannot be defined uniformly, but it is usually preferably about 20 seconds to 300 seconds.

<Resin film lamination process>
Next, as a method of laminating another resin film on either one or both surfaces of the resin film with circuit (resin film on which a metal circuit is formed) obtained as described above, adhesion is possible. A method of laminating a resin film with an adhesive resin 70 on one surface of a resin film with circuit by laminating, and a metal circuit is still formed after the adhesive resin 70 is applied to the metal circuit forming surface of the resin film with circuit There is a method of laminating a non-resin film by lamination, and the resin film can be laminated as shown in FIG. 9 by any method.

  In addition, according to the latter method of laminating a resin film, when the thickness of the metal circuit is large, surface unevenness of the resin film due to the metal circuit can be reduced, so that there is an advantage that the bonding strength can be further increased.

Moreover, it is preferable that the temperature when another resin film 100 is laminated | stacked with respect to either the surface or both surfaces of the resin film with a circuit mentioned above is 30-300 degreeC, and the pressure applied to lamination | stacking is 0. It is preferable that it is 1-20 kg / cm < ² >. Moreover, it is preferable that the time taken for lamination | stacking of this resin film is 1 second or more and 3 hours or less.

  Then, the multilayer laminated circuit board of the present invention as shown in FIG. 1 can be manufactured by repeating each of the above-described steps such that a conductive via forming step is performed thereafter. EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
In Example 1, an etching method was employed as a method for forming a metal circuit, and a multilayer laminated circuit board was produced by the following steps.

<Conductive via formation process>
As a resin film 100 used for a multilayer laminated circuit board, a long polyimide film wound in a roll shape (length 50 m, thickness 38 μm, trade name: Kapton EN150 (manufactured by Toray DuPont Co., Ltd.)) was used. . The resin film had a thermal expansion coefficient of 16 ppm / ° C. or more and 17 ppm / ° C. or less, and a slit processed with a width of 250 mm was used. This resin film 100 was set in a UV-YAG laser device, a program for the UV-YAG laser device was set, and three conductive vias 120 having an inner diameter of 15 μm were formed in one multi-conductive portion (FIG. 4).

<Washing process>
The resin film 100 having the conductive vias 120 formed thereon was set in a cleaning device, and the surface of the resin film 100 was cleaned in order to suppress the occurrence of pinholes in the base layer forming process.

<Underlayer formation process>
Next, the resin film 100 whose surface has been cleaned is put in a sputtering apparatus, set to a pressure of 1 × 10 ⁻³ Pa by a vacuum pump, and N ₂ gas is injected into the ion gun and irradiated. Thus, the surface of the resin film was pretreated. Thereafter, an antioxidant layer made of an alloy of Ni and Cr (weight ratio of Ni and Cr is Ni: Cr = 80: 20) is formed on the resin film in an Ar atmosphere by a sputtering method, and Cu is formed thereon. By forming the underlying metal layer, the underlying layer 130 was formed (FIG. 5).

  Then, the vacuum state of the sputtering apparatus was released, the resin film 100 on which the base layer 130 was formed was taken out, and a part of the resin film 100 was sampled. And the cross section was observed by irradiating the sample with a focused ion beam (FIB). As a result, it was confirmed that the antioxidant layer had a thickness of 10 nm and the base metal layer had a thickness of 350 nm. Furthermore, it was confirmed that these base layers 130 were also formed in the conductive vias 120.

<Plating layer formation process>
Next, the resin film 100 on which the underlayer was formed was set in a copper plating apparatus, the underlayer was activated with sulfuric acid, and then washed with water. Thereafter, the resin film is immersed in a plating bath filled with a plating solution (containing 200 g / l sulfuric acid, 90 g / l copper sulfate, and a chlorine ion concentration of 50 ppm), thereby performing copper plating on the base layer 130 and again. Washed with water and dried to form a plating layer 140 on the surface of the resin film 100 (FIG. 10). A part of the resin film thus obtained was sampled. And when the cross section was observed by irradiating FIB with respect to the sample, the total thickness including the base layer 130 and the plating layer 140 was 18.5 micrometers.

<Metal circuit formation process>
Next, a 250 mm wide slit-processed dry film (trade name: NIT215 (manufactured by Nichigo Morton)) is laminated on both the front and back surfaces of the resin film 100 on which the plating layer 140 is formed as described above. Then, after the metal circuit pattern masks were superposed, they were set in a roll type exposure apparatus and exposed.

  Thereafter, the resin film 100 was set in a roll-type etching apparatus capable of continuously performing development, etching, and resist peeling, and an etching process was performed to form a metal circuit 50 (FIG. 8). This resin film was sampled, and the metal circuit 50 was inspected for disconnection, short-circuiting, etc. with a microscope with a magnification of 100 times. As a result, no defects such as disconnection or short circuit were observed in the metal circuit 50 shown in FIG.

<Resin film lamination process>
Next, a 38 μm-thick polyimide film (Kapton EN150 (manufactured by Toray DuPont Co., Ltd.)) coated with adhesive resin 70 is pasted on both the front and back surfaces of resin film 100 on which a metal circuit is formed as described above. A laminate composed of the three-layer resin film 100 and the two-layer circuit layer 200 was obtained (FIG. 9).

  The entire surface of the upper and lower resin films 100 of this laminate was inspected for wrinkles, air bites, etc. using a 5x magnifier. As a result, defects such as wrinkles and air biting were not observed in the upper and lower resin films of the laminate.

<Conductive via formation process-2>
Next, by using the same method as the conductive via forming step described above, three conductive vias 120 were formed in each multi-conductive portion with respect to the upper and lower resin films 100 of the laminate obtained above (FIG. 11). ). Thereafter, the surfaces of the upper and lower resin films 100 of the laminate on which the conductive vias were formed as described above were washed.

<Underlayer formation process-2>
Next, the laminated body obtained above is set in a sputtering apparatus, and the surface of the upper and lower resin films 100 of this laminated body is formed of Ni—Cr by the same conditions and method as the above-described underlayer forming step. A base layer 130 including a layer and a base metal layer made of Cu was formed by a sputtering method (FIG. 12).

  Then, a part of the laminated body on which the base layer was formed was sampled. And the cross section was observed by irradiating FIB with respect to the sample. As a result, it was confirmed that the antioxidant layer had a thickness of 10 nm and the base metal layer had a thickness of 350 nm.

<Plating layer forming step-2>
Next, the laminate on which the base layer obtained above was formed was set in a Cu plating apparatus, and the plating layer 140 was formed on the entire surface of the base layer formed above under the same conditions as in the plating layer formation step described above. (FIG. 13). Thereafter, a part of this laminate was sampled and irradiated with FIB to observe the cross section. As a result, it was confirmed that the total thickness of the plating layer 140 and the base layer 130 on the upper and lower resin films 100 of this laminate was 18.5 μm.

<Metal circuit formation process-2>
Next, a dry film (trade name: NIT215 (manufactured by Nichigo Morton Co., Ltd.)) is laminated on the upper and lower resin films 100 of the laminate formed with the plating layer obtained above, and then roll type It was set in an exposure apparatus and exposed.

  Thereafter, development, etching, and resist stripping were successively performed, and metal circuits 50 were formed on the upper and lower surfaces of the resin film 100 of the laminate (FIG. 1). The multilayer laminated circuit board of the present invention was produced as described above.

  This was sampled, and this sample was inspected for disconnection, short circuit, etc. of the metal circuit using a 100 × microscope. As a result, defects such as disconnection and short circuit were not observed in the metal circuit of the multilayer laminated circuit board.

<Examples 2 to 12>
The multilayer laminated circuit boards of Examples 2 to 12 differ from the multilayer laminated circuit board of Example 1 in the number of conductive vias at one location of the multi-conductive portion and the inner diameter of the conductive vias as shown in Table 1 below. Except for this, it was produced by the same method as in Example 1. For example, Example 3 in Table 1 shows that five conductive vias similar to the conductive via formed in Example 1 were formed for one multi-conducting part, and Example 5 was a single multi-conducting part. Shows that three conductive vias having an inner diameter of 50 μm were formed.

<Comparative Examples 1-3>
The multilayer laminated circuit boards of Comparative Examples 1 to 3 were produced by the same method as in Example 1 except that the multi-conductive portion was not formed and one conductive via was formed for one conductive portion ( (See Table 1). For example, in Table 1, it is shown that a conductive via having an inner diameter of 15 μm is formed in Comparative Example 1, a conductive via having an inner diameter of 50 μm is formed in Comparative Example 2, and a conductive via having an inner diameter of 300 μm is formed in Comparative Example 3.

<Continuity test>
Using the LCR meter (product number: NDH-2000 (manufactured by Custom Co., Ltd.)) for the multilayer laminated circuit boards of Examples 1 to 12 and Comparative Examples 1 to 3, continuity inspection at both terminals of the multilayer laminated circuit board is performed. I did it. As a result, no abnormality in conduction was observed in any of the multilayer laminated circuit boards of Examples 1 to 12 and Comparative Examples 1 to 3.

  The metal circuits of the multilayer laminated circuit boards of Examples 1 to 12 and Comparative Examples 1 to 3 are provided with approximately 200 multi-conducting portions (conducting portions in the comparative example). In the example, if disconnection occurs even at one part of the conduction part), an abnormality in conduction is measured, and thus it has been clarified that the metal circuit is not disconnected at the stage of producing the multilayer circuit board. .

<Temperature change cycle test>
Using the cycle tester (model: TSA-41L-A (manufactured by ESPEC Corporation)) for the multilayer laminated circuit boards of Examples 1-12 and Comparative Examples 1-3, two different set temperatures are set at regular time intervals. A temperature change cycle test was conducted in which the sample was held alternately and repeatedly. Specifically, holding at −40 ° C. for 30 minutes and then holding at 120 ° C. for 30 minutes was defined as one cycle, and a continuity test was performed every 500 cycles. The cycle test was terminated when a continuity failure occurred in one of a plurality of multi-conducting portions included in the circuit, and up to 3000 cycles were performed.

  In the multilayer laminated circuit boards of Examples 1 to 12, no poor conduction was observed even at the end of 3000 cycles. In contrast, the multilayer laminated circuit board of Comparative Example 1 was confirmed to have poor conduction at the end of 2000 cycles, the multilayer laminated circuit board of Comparative Example 2 at the end of 1500 cycles, and the multilayer laminated circuit board of Comparative Example 3 at the end of 1000 cycles. It was done.

  From the above results, it is clear that the multilayer laminated circuit boards of Examples 1 to 12 are much less susceptible to disconnection of the metal circuit when heat is applied than the multilayer laminated circuit boards of Comparative Examples 1 to 3. became. This is obviously due to the provision of the multi-conducting portion on the multilayer laminated circuit boards of Examples 1-12.

  Although the embodiments and examples of the present invention have been described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  ADVANTAGE OF THE INVENTION According to this invention, the multilayer laminated circuit board which cannot produce a disconnection of a metal circuit can be provided.

It is typical sectional drawing which shows an example of the multilayer laminated circuit board of this invention. It is an enlarged plan view from the upper surface of the multi conduction | electrical_connection part of FIG. It is typical sectional drawing which shows an example of the usage condition of the multilayer laminated circuit board of this invention. It is typical sectional drawing which shows the resin film after forming a multi conduction | electrical_connection part. It is typical sectional drawing which shows the resin film after forming a base layer. It is typical sectional drawing which shows the resin film after developing a resist. It is typical sectional drawing which shows the resin film after forming a plating layer. It is typical sectional drawing which shows the resin film after carrying out a soft etching. It is typical sectional drawing which shows the state which laminated | stacked the resin film on the both surfaces of the front and back of the resin film which formed the metal circuit. It is typical sectional drawing which shows the resin film after forming a plating layer in a base layer. It is typical sectional drawing which shows the state after forming a conduction | electrical_connection via in the upper and lower surfaces of the laminated body which laminated | stacked three resin films. It is typical sectional drawing which shows the state after forming a base layer in the upper and lower surfaces of the laminated body which laminated | stacked three resin films. It is typical sectional drawing which shows the state after forming a plating layer on the upper and lower surfaces of the laminated body which laminated | stacked three resin films.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Multilayer laminated circuit board, 50 Metal circuit, 70 Adhesive resin, 100 Resin film, 110 Multi conduction | electrical_connection part, 120 Conduction via | veer, 130 Underlayer, 140 Plating layer, 170 Resist, 200 Circuit layer, 301 Rigid board, 302 Si board 401 Adhesive metal, 402 Adhesive metal.

Claims (5)

A multilayer circuit board including a laminated structure in which resin films and circuit layers are alternately laminated,
The resin film has one or more multi-conductive portions,
The multi-conductive portion occupies a region having a diameter of 10 μm or more and 3000 μm or less, and has two or more conductive vias,
The conductive via is a multilayer laminated circuit board having an inner diameter of 5 μm or more and 300 μm or less. The thickness of the resin film is T,
The multilayer laminated circuit board according to claim 1, wherein 0 <d / T ≦ 60, where d is an inner diameter of the conductive via.   The multilayer resin circuit board according to claim 1, wherein the resin film is processed and used in a long shape.   A component or product using the multilayer laminated circuit board according to claim 1.   The product according to claim 4, wherein the product is one of an electrical product, an electronic product, a semiconductor product, an antenna circuit board, an IC card, a solar cell, an automobile, and a robot.

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