JP2005347308A - Method for manufacturing multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a step or shorten a plating time, or to form a metal pad for connection which is superior in bondability. <P>SOLUTION: This method includes a step to form a wiring layer on a conductive supporting body, a step to form a solder resist layer having an opening as corresponding to a connection part on the wiring layer, a step to apply metallic plating in the opening of the solder resist by electrolytic plating and to form a metallic pad for connection, and a step to transfer the laminated body formed in every step on a substrate where a conductor for interlayer connection penetrates. After the laminated body transferred on the conductive supporting body is transferred onto a support film, the laminated body transferred onto the support film may be further transferred onto the substrate. The wiring layer or the metal pad for connection is formed by electrolytic plating while the conductive supporting body is used as an electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer wiring board, and more particularly to a novel method for manufacturing a multilayer wiring board capable of efficiently forming an outermost layer.

  In order to manufacture a so-called build-up multilayer wiring board, it is necessary to sequentially laminate an insulating layer and a conductor layer, pattern each conductor layer into a predetermined wiring pattern, and achieve interlayer connection between the conductor layers. The formation of fine patterns and the realization of efficient interlayer connection are important technologies.

Conventionally, a method using a so-called semi-additive method has been frequently used as a method for manufacturing a build-up multilayer wiring board. This is because the semi-additive method is advantageous in terms of fine pattern formation. Various techniques have also been proposed for interlayer connection (see, for example, Patent Document 1 to Patent Document 4).
JP 2003-7768 A Japanese Patent Publication No.46-31566 JP 60-134495 A JP 2000-332369 A

  By the way, in the manufacture of the multilayer wiring board, after finishing the lamination of each layer and interlayer connection, a solder resist layer is formed to cover the outermost wiring layer, and the outermost wiring layer is protected, and the external connection portion is formed. Correspondingly, it is necessary to form a metal pad for connection.

  Usually, the formation of the solder resist layer and the formation of the connection metal pad for external connection are performed last after the multilayering is completed. That is, after completion of all the lamination processes, a solder resist layer is formed on the surface of the outermost layer, and a connection metal pad is formed by plating in an opening formed corresponding to the external connection portion. In this case, the plating method is limited to electroless plating.

  However, when the connection metal pad is formed by electroless plating, not only does the plating process take a long time, but there is a problem that dissatisfaction remains in terms of bondability and the solder resist layer is also damaged greatly. In addition, gold plating having excellent corrosion resistance is adopted for the metal pad for connection, but there are problems such as high cost of electroless gold plating and difficulty in partial gold plating.

  Further, when the connection metal pads are formed after the multi-layering is completed, it is necessary to form the connection metal pads collectively on the front and back of the multilayer wiring board. For example, it may be required to increase the thickness of the connection metal pad on the bonding surface of the multilayer wiring board, and to decrease the thickness of the connection metal pad on the solder surface. It is difficult to change the thickness of the metal pad for connection between the front and back sides. Similarly, for example, a metal pad for connection is made of gold on the bonding surface of the multilayer wiring board and a metal pad for connection is formed of solder on the solder surface. In some cases, it is still difficult to cope with the conventional method.

  The present invention has been proposed to solve these problems of the prior art, and can simplify the process and shorten the plating time, and can form a metal pad for connection with excellent bondability. Thus, an object of the present invention is to provide a method for manufacturing a multilayer wiring board capable of reducing damage to a solder resist. Another object of the present invention is to provide a method for manufacturing a multilayer wiring board that can be formed with different plating on the front and back sides and can change the film thickness and material of the connecting metal pads on the front and back sides.

  In order to achieve the above-described object, a method for manufacturing a multilayer wiring board according to the present invention includes a step of forming a wiring layer on a conductive support, and a solder resist layer having an opening corresponding to the connection portion. Forming a metal pad for connection by electrolytic plating on the opening of the solder resist layer and forming a connection body pad through the layered body formed by the respective processes. And a step of transferring onto the substrate.

  In the method for producing a multilayer wiring board according to the present invention, the solder resist layer and the connection metal pad are not formed after the multilayering is completed, but the solder resist layer is superimposed on the outermost wiring layer on the conductive support. And a connecting metal pad is formed and transferred onto the substrate.

  Therefore, the wiring layer and the connecting metal pad can be formed by electrolytic plating using the conductive support as an electrode, and the plating time is shortened. In addition, bondability is ensured in the metal pad for connection, and the solder resist layer is not damaged.

  Furthermore, in the manufacturing method of the multilayer wiring board of the present invention, the outermost layer, the connecting metal pad, and the solder resist layer are formed on the conductive support, and this is transferred onto the substrate. Different plating can be performed. Therefore, it is possible to change the film thickness and material of the connecting metal pads on the front and back sides, and design according to requirements is possible.

  According to the multilayer wiring board manufacturing method of the present invention, the process can be simplified and the plating time can be shortened, the metal pad for connection with excellent bondability can be formed, and the damage to the solder resist is also reduced. Is possible. Further, according to the present invention, different plating can be formed on the front and back sides, and the film thickness and material of the connection metal pad can be changed on the front and back sides.

  Hereinafter, a method of manufacturing a multilayer wiring board to which the present invention is applied will be described in detail with reference to the drawings.

(First embodiment)
In the present embodiment, an outermost wiring layer and a solder resist layer, and further a connection metal pad are formed on a conductive support, and a laminate composed of these layers is peeled off from the conductive support and placed on the substrate. This is an example of transferring.

  In this embodiment, first, as shown in FIG. 1A, a peelable metal plate 1 that is a conductive support is prepared. For the peelable metal plate 1, for example, a clad material composed of a support metal plate 2 having sufficient mechanical strength and a metal thin layer 3 having etching selectivity with respect to copper constituting the wiring layer is used. The thin metal layer 3 having etching selectivity with respect to copper is, for example, a Ni layer. Of course, the conductive support is not limited to this, and any conductive support may be used as long as it is made of a material that has conductivity and can be peeled off from the laminate formed thereon. A simple metal plate may be used instead of the material.

  First, pattern plating is performed on the peelable metal plate 1 to form a wiring layer. Specifically, first, a resist pattern 4 having an inverted pattern obtained by inverting the pattern of the wiring layer is formed on the surface of the peelable metal plate 1. The patterning of the resist pattern 4 may be performed by a normal photolithography technique or the like. Then, the conductive peelable metal plate 1 is used as an electrode, and electroplating is performed to form the wiring layer 5. At this time, for example, electroless plating is not required, and the wiring layer 5 is formed only by, for example, electrolytic copper plating. If the resist pattern 4 is formed and electroplating is performed, a plating layer is formed only on a portion where the peelable metal plate 1 which is a conductive support is exposed, and no plating layer is formed on the resist pattern 4. Therefore, the wiring layer 5 composed of the reverse pattern of the resist pattern 4 is formed.

  Next, as shown in FIG. 1B, a solder resist layer 6 is formed on the wiring layer 5 and the resist pattern 4, and further a connection metal pad 7 is formed. The solder resist layer 6 can be formed of a known solder resist material. For example, a photosensitive solder resist material is patterned by a photolithography technique or the like to form the opening 6 a corresponding to the terminal portion 5 a of the wiring layer 5. .

  Then, a connection metal pad 7 is formed in the opening 6a of the solder resist layer 6 by plating. The connection metal pad 7 is formed by, for example, gold plating. However, the formation of the connection metal pad 7 does not require electroless plating, and can be formed only by electrolytic plating. That is, the terminal portion 5a of the wiring layer 5 faces the opening 6a of the solder resist layer 6, and the terminal portion 5a of the wiring layer 5 is a conductive support (peelable metal plate) disposed on the back surface thereof. 1) and can be used as an electrode. Therefore, when, for example, electrolytic Ni-Au plating is performed on the peelable metal plate 1 on which the solder resist layer 6 is formed, an electrolytic plating layer is formed on the terminal portion 5a, and the connecting metal pad 7 is formed. .

  Next, as shown in FIG. 1C, the laminate 8 composed of the resist pattern 4, the wiring layer 5, the solder resist layer 6, and the connection metal pad 7 formed as described above is a peelable that is a conductive support. Peel from the metal plate 1. The peeling method should just employ | adopt the optimal method according to the structure of the peelable metal plate 1. FIG. For example, when peeling at the interface between the thin metal layer 3 constituting the peelable metal plate 1 and the laminate 8 is easy, the peelable metal plate 1 may be simply mechanically peeled off from the laminate 8. The same applies to the case where the peelable metal plate 1 is a single metal plate. On the other hand, when peeling at the interface between the support metal plate 2 and the metal thin layer 3 constituting the peelable metal plate 1 is easy, first, the support metal plate 2 is peeled off, and then the metal thin layer 3 is peeled off. Are removed by etching. Therefore, in this case, the thin metal layer 3 needs to have etching selectivity with respect to the wiring layer 5.

  The laminated body 8 peeled off from the peelable metal plate 1 is superimposed and joined and integrated as the outermost layer of the substrate 10 on which the conductive pins 9 for interlayer connection are driven, for example. At this time, the laminates 8 respectively prepared by the steps of FIG. 1A to FIG. 1C are bonded to both surfaces of the substrate 10, respectively. The laminated state is shown in FIG. Each laminated body 8 is joined such that the wiring layer 5 is in contact with the conductive pin 9 and the outermost surface is protected by the solder resist layer 6. Further, the connection metal pad 7 faces the outside as a connection pad for external connection, and the connection metal pad 7 is connected by bonding or soldering.

  Here, for the sake of simplification of the configuration, the substrate 10 is simply a substrate having a configuration in which the conductive pins 9 for interlayer connection are driven. It may be a multilayer substrate having layers. The substrate 10 may be a rigid substrate or a flexible substrate, and may be a rigid flex substrate or the like. The material is also arbitrary, such as thermosetting polyimide, thermoplastic polyimide, prepreg, LCP, and curing material + NCP. The interlayer connection may use the conductive pins 9 as described above, or may be through holes, bumps, via holes filled with a conductive paste, or the like.

  When the substrate 10 with the conductive pins 9 driven in is used as described above, the cylindrical connection pins (conductive pins 9) are attached to the substrate 10 by a known implant method (see Japanese Patent Application Laid-Open No. 2003-197692). The conductive pins 9 are penetrated in the thickness direction so that both ends of the conductive pins 9 protrude from the surface of the substrate 10.

The material of the conductive pin 9 is not particularly limited, but from the viewpoint of ensuring conduction reliability, it is preferable to use a material that is softer than, for example, the electrolytic copper foil that constitutes the wiring layer 5, and as a particularly preferable material, And oxygen-free rolled copper (oxygen-free copper processed by rolling). Oxygen-free copper is not only those specified in Japanese Industrial Standards JIS C1011 and JIS C1020, but also tough pitch copper (TPC, chemical component → Cu: 99.95 wt% O ₂ : 0.035 wt%) specified in JIS C1100. Shall be included. However, from the viewpoint of improving the conduction reliability, it is preferable to use those specified in JIS C1011 and JIS C1020.

  The height at which both ends of the conductive pin 9 protrude from the surface of the substrate 10 is not particularly limited. However, from the viewpoint of ensuring conduction reliability, it is not preferable to protrude too much, and conversely, the amount of protrusion is insufficient. Even if it is not preferable. In consideration of these, specifically, the protruding height is preferably about 3 μm to 10 μm.

  The laminates 8 are bonded to both surfaces of the substrate 10, respectively. For the bonding, for example, anisotropic conductive adhesive (ACF) 11 or the like is used. It is necessary to electrically connect the conductive pin 9 for interlayer connection and the wiring layer 5 of the laminate 8, but when the anisotropic conductive adhesive 11 is interposed, only the portion pressed by the conductive pin 9 is thick. Conduction is achieved in the vertical direction. The method of electrically connecting the conductive pins 9 for interlayer connection and the wiring layer 5 of the laminated body 8 is not limited to this, and any method such as soldering, gold bonding, or Sn-Ag bonding may be used. .

  The laminated body 8 joined to the front and back of the substrate 10 is formed in separate steps by the steps shown in FIGS. 1 (a) to 1 (c). Therefore, for example, the configuration of the connection metal pad 7 is changed between the stacked body 8 stacked on the front surface (upper surface in the drawing) of the substrate 10 and the stacked body 8 stacked on the back surface (lower surface in the drawing) of the substrate 10. It is possible. For example, in the laminate 8 bonded to the front and back of the substrate 10, the thickness of the connection metal pad 7 can be arbitrarily set. Specifically, the film thickness of the connection metal pad 7 on the bonding surface side can be set thick, and the film thickness of the connection metal pad 7 on the solder surface can be set thin. Alternatively, the material of the connection metal pad 7 can be arbitrarily set in the laminate 8 bonded to the front and back of the substrate 10. Specifically, the material of the connection metal pad 7 on the bonding surface side can be gold and the material of the connection metal pad 7 on the solder surface can be solder by different metal plating. As described above, since the laminate 8 bonded to the front and back of the substrate 10 is formed in a separate process, dissimilar metal plating is easy.

  As described above, in the manufacturing method of the present embodiment, the wiring layer 5 and the connection metal pad 7 are formed on the peelable metal plate 1 which is a conductive support. The connection metal pad 7 can be formed only by electrolytic plating, and a process such as electroless plating is unnecessary. Therefore, the plating process can be simplified and the time required for plating can be greatly shortened.

  In particular, since the connection metal pad 7 is usually formed by electroless gold plating only by electrolytic gold plating, all the conventional problems can be improved. That is, the bondability of the connecting metal pad 7 can be improved, and the solder resist layer 6 is not damaged during the formation. Partial plating is also easy.

  Furthermore, according to the manufacturing method of the present embodiment, it is possible to change the film thickness and material of the connection metal pad 7 between the front and back of the substrate 10, and it is possible to have a configuration suitable for each surface. . As a result, for example, it is possible to have a configuration suitable for bonding on the bonding surface and a configuration suitable for soldering on the solder surface.

(Second Embodiment)
In this embodiment, when peeling the laminated body 8 from the peelable metal plate 1, it is an example which bonded the support film and made the handling easy. Other steps are basically the same as those in the first embodiment. The manufacturing process of this embodiment is shown in FIG.

  That is, also in the manufacturing method of this embodiment, as shown in FIG. 2A, the peelable metal plate 1 is prepared, and the resist pattern 4 and the wiring layer 5 are formed thereon. Further, as shown in FIG. 2B, a solder resist layer 6 is formed thereon, and a connection metal pad 7 is formed in the opening 6 a of the solder resist layer 6.

  Thereby, a laminate 8 is formed, and this laminate 8 is transferred onto the substrate 10. At this time, in this embodiment, the support 8 is used to transfer the laminate 8 once onto the support film 12. Then, the image is transferred to the substrate 10. That is, as shown in FIG. 2C, after the formation of the laminate 8, the support film 12 is overlaid on the laminate 8 and bonded together. The support film 12 may be any film as long as it has a certain degree of mechanical strength, and a film or sheet of any material such as a plastic film or a metal sheet can be used. The support film 12 is preferably formed with an adhesive layer or the like on the surface in contact with the laminate 8 so that the transfer state is stable.

  Next, as shown in FIG. 2 (d), the peelable metal plate 1 is peeled from the laminate 8, and the laminate 8 is transferred onto the support film 12. As a result, the front and back of the laminate 8 are reversed. In this state, as shown in FIG. 2 (e), the laminated body 8 supported by the support film 12 is superposed on both surfaces of the substrate 10 and bonded together. Finally, as shown in FIG. 2 (f), the support film 12 is peeled from the laminate 8.

  The wiring layer 5, the solder resist layer 6, and the connection metal pad 7 constituting the stacked body 8 are thin and the strength of the entire stacked body 8 may not be sufficient. In such a case, it is difficult to handle the laminated body 8 peeled from the peelable metal plate 1 alone as in the first embodiment. In this embodiment, since the laminated body 8 is supported by the support film 12, it becomes easy to handle and can be reliably transferred onto the substrate 10 in a good state.

The manufacturing process in 1st Embodiment is shown, (a) is schematic sectional drawing which shows a wiring layer formation process, (b) is schematic sectional drawing which shows the formation process of a soldering resist layer and the metal pad for connection, ( c) is a schematic cross-sectional view showing the step of peeling the laminate, and (d) is a schematic cross-sectional view showing the step of joining the laminate to the substrate. The manufacturing process in 2nd Embodiment is shown, (a) is a schematic sectional drawing which shows a wiring layer formation process, (b) is a schematic sectional drawing which shows the formation process of a soldering resist layer and the metal pad for connection, ( c) is a schematic cross-sectional view showing a support film laminating step, (d) is a schematic cross-sectional view showing a peelable metal plate peeling step, (e) is a schematic cross-sectional view showing a step of bonding a laminate to a substrate, (f) ) Is a schematic cross-sectional view showing a support film peeling step.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Peelable metal plate, 2 Support metal plate, 3 Metal thin layer, 4 Resist pattern, 5 Wiring layer, 6 Solder resist layer, 7 Metal pad for connection, 8 Laminated body, 9 Conductive pin, 10 Substrate, 11 Anisotropic conductivity Adhesive, 12 Support film

Claims (6)

Forming a wiring layer on the conductive support;
Forming a solder resist layer having an opening corresponding to the connecting portion on the wiring layer;
Forming a metal pad for connection by applying metal plating to the opening of the solder resist layer by electrolytic plating;
A method of manufacturing a multilayer wiring board, comprising: transferring the laminated body formed in each of the above steps onto a substrate through which an interlayer connection conductor is formed.   2. The method of manufacturing a multilayer wiring board according to claim 1, wherein a resist pattern is formed on a conductive support, and the wiring layer is formed by pattern plating by electrolytic plating.   2. The method of manufacturing a multilayer wiring board according to claim 1, wherein the laminate is peeled off from the conductive support and bonded onto the substrate so that the solder resist layer side is the outermost surface.   2. The method for manufacturing a multilayer wiring board according to claim 1, wherein after the laminate on the conductive support is transferred onto a support film, the laminate transferred onto the support film is further transferred onto the substrate. .   2. The method for manufacturing a multilayer wiring board according to claim 1, wherein the conductive support is composed of a supporting substrate and a metal thin film formed on a wiring layer forming surface of the supporting substrate. 2. The method for manufacturing a multilayer wiring board according to claim 1, wherein the conductor for interlayer connection is a conductive pin, and the conductive pin is driven so as to penetrate the substrate.