JP2004200260A - Method for manufacturing flexible rigid build-up multilayer wiring board - Google Patents

Abstract

Provided is a method for manufacturing a flexible rigid build-up wiring board which does not require a part of a build-up layer to be peeled off after lamination on a flexible rigid printed wiring board.
Prior to lamination on a flexible rigid printed wiring board (20), a build-up layer (27) is processed to correspond to a portion to be a cable connection part (26) of the flexible rigid printed wiring board (20). The part (29) has been removed. A low flow type resin is used as a material for the build-up layer (27).
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a flexible rigid build-up wiring board in which a build-up layer is laminated on a flexible rigid printed wiring board for forming a fine circuit and the like. Therefore, the present invention relates to a method of manufacturing a flexible rigid build-up wiring board from which a part of a build-up layer has been removed.
[0002]
[Prior art]
Flexible rigid build-up wiring boards usually use a flexible rigid printed wiring board as a core material (inner layer), and copper plating is applied to the build-up insulating resin as the outer layer, or copper foil is provided on the build-up insulating resin. RCC (abbreviation of copper foil with build-up insulating resin) is predominant (hereinafter, build-up insulating resin with metal plating or metal foil is collectively referred to as build-up layer).
[0003]
FIG. 1 is a cross-sectional view showing an example of a conventional flexible rigid build-up wiring board. The flexible rigid build-up wiring board has a flexible rigid wiring board 10 as a core material, and a build-up layer 17 as an outer layer is laminated on the flexible rigid wiring board 10. The flexible rigid wiring board 10 has an FPC (flexible substrate) substrate 11 and a film cover lay 12 mainly composed of a polyimide resin provided on both surfaces of the FPC substrate 11, and a central portion of each film cover lay 12 is exposed. In this state, it has a glass epoxy resin layer 14 laminated on each film coverlay 12 via an adhesive layer 13.
[0004]
The FPC substrate 11 of the flexible rigid printed wiring board 10 is formed by forming conductors 11b on both surfaces of a base film 11a by copper plating or the like. The flexible rigid printed wiring board 10 includes a film cover lay 12 that covers both surfaces of the FPC base material 11, and a film cover lay that is exposed through an adhesive layer 13 with a central portion of each film cover lay 12 exposed. The glass epoxy resin layer 14 is laminated on the glass epoxy resin 12, and each glass epoxy resin 14 has a conductor 15 such as copper plating provided to form a circuit. Such a flexible rigid printed wiring board 10 has a single-layer wiring structure on both sides of the FPC substrate 11.
[0005]
On each glass epoxy resin layer 14 of the flexible rigid printed wiring board 10, a build-up layer 17 is laminated so as to cover the conductor 15, and a conductor 18 is further formed on the outermost layer by copper foil or copper plating. A build-up wiring board is configured. The flexible rigid build-up wiring board has a two-layer laminated wiring structure on both sides of the FPC substrate 11.
[0006]
At the center of each film coverlay 12 where the glass epoxy resin layer 14 is not laminated on the flexible rigid printed wiring board 10, a cable connection portion 16 to which an FPC is connected is formed. The build-up layer 17 is not laminated on each cable connection portion 16, and as a result, is exposed from the glass epoxy resin layer 14.
[0007]
The flexible rigid build-up wiring board having such a configuration is usually manufactured by a photo via method or a laser method. JP-A-11-26945 discloses a method of manufacturing a flexible rigid build-up wiring board by a photo via method.
[0008]
When manufacturing a flexible rigid build-up wiring board by a photo via method, first, a flexible rigid printed wiring board 10 is prepared. A flexible rigid printed wiring board 10 is formed by providing conductors 11b on both sides of a base film 11a to form an FPC base material 11, and laminating a film cover lay 12 mainly composed of a polyimide resin on both sides of the FPC base material 11, A glass epoxy resin layer 14 is laminated on each film cover lay 12 via an adhesive layer 13 with the central portion of the cover lay 12 exposed.
[0009]
After preparing the flexible rigid printed wiring board 10, a circuit is formed by the conductor 15 on the outer layer side of each glass epoxy resin layer 14.
[0010]
Next, of the respective glass epoxy resin layers 14, only the central portion sandwiched between the respective side portions is selectively removed by die punching, and as shown in FIG. Each cable connection part 16 of the board 10 is exposed. After this state, as shown in FIG. 2B, the conductor 15 on each glass epoxy resin layer 14 is etched, and the flexible rigid printed wiring board 10 is Then, a build-up layer 17 is laminated. Each buildup layer 17 is made of a photosensitive resin, and the surface of each buildup layer 17 is formed flat.
[0011]
Thereafter, each of the build-up layers 17 is selectively irradiated with an ultraviolet ray so that a blind via hole 19 having a diameter of about 70 to 150 μm is formed in the rigid portion 17 c of the build-up layer 17, and a glass epoxy resin is formed. Each of the build-up layers 17 is selectively treated with a chemical solution such that only the side edge portion 17a close to the layer 14 is removed and the central portion 17b remains. At this time, there is no possibility that the upper part of the cable connection part 16 covered with each central part 17b is damaged by the chemical solution treatment. Next, a conductor 18 is formed by copper foil or copper plating, solder resist formation and surface treatment are sequentially performed, and a central portion 17b of the build-up layer 17 remaining on each cable connection 16 is removed. All of the cable connection portions 16 are exposed. Thereby, the flexible rigid build-up wiring board shown in FIG. 1 is obtained.
[0012]
In such a method of manufacturing a flexible rigid build-up wiring board, formation of a blind via hole in a build-up layer using a laser has recently become mainstream due to speeding up and stabilization of a laser device. When the brand via hole 19 is formed by a laser method, a predetermined position of the rigid portion 17c of the build-up layer 17 is irradiated with a laser beam. Further, the build-up layer 17 on the cable connection portion 16 is peeled off after the lamination, and the cable connection portion 16 is exposed. As a laser beam for forming the blind via hole on the rigid portion 17c of the build-up layer 17, a carbon dioxide gas laser, a UV-YAG laser, or the like is mainly used.
[0013]
[Patent Document 1] Japanese Patent Application Laid-Open No. H11-26945
[Problems to be solved by the invention]
Generally, the build-up layer in the case of a rigid build-up wiring board has a structure in which the resin completely flows between the circuits by pressurization and heating during lamination in order to improve the embedding property in the inner layer circuit (hereinafter, flow is referred to as “flow-up”). It is an essential condition to ensure insulation properties. On the other hand, in the build-up layer in the case of the flexible rigid build-up wiring board, in addition to the above-mentioned essential conditions, in order to open the cable connection section 16, the flowed build-up layer on the cable connection section 16 is later removed by some method. A peeling step is required. At present, the cost and the operation time of this peeling step are enormous, and it is desirable that it can be omitted.
[0015]
In order to omit the peeling step, in addition to the condition for ensuring the embedding of the resin into the inner layer circuit, the condition that the resin is opened on the cable connecting portion 16 without flowing is required. However, the resin used for the ordinary build-up layer cannot satisfy this requirement, and if the conventional manufacturing method is followed, it is necessary to newly develop a resin whose flow can be controlled.
[0016]
The present invention has been made in view of such a problem, and provides a method of manufacturing a flexible rigid build-up wiring board which does not require peeling off a part of a build-up layer after lamination on a flexible rigid printed wiring board. The purpose is to:
[0017]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a method of manufacturing a flexible rigid build-up wiring board in which a build-up layer is laminated so that a part thereof is exposed on a flexible rigid printed wiring board is provided. A removal processing step of processing the build-up layer before lamination on the board and removing a portion corresponding to an exposed part of the flexible rigid printed wiring board; and a lamination step of laminating the build-up layer on the flexible rigid printed wiring board. A laser processing step of processing the build-up layer with a laser for interlayer connection, and a chemical processing step of removing a residue after the laser processing with a chemical.
[0018]
In this manufacturing method, before laminating on a flexible rigid printed wiring board, a portion for exposing the wiring board is processed by processing the build-up layer. Therefore, the step of peeling a part of the build-up layer from the flexible rigid printed wiring board is unnecessary. Moreover, it is not necessary to use a resin whose flow control is easy particularly as the material of the build-up layer, and a conventional low flow type resin can be used.
[0019]
In the removal processing step, die processing can be employed, and router processing can also be employed.
[0020]
The build-up layer can be produced either by providing a metal foil on the low-fluidity insulating resin layer or by plating the low-fluidity insulating resin layer with metal.
[0021]
Also, after the laminating step and before the chemical processing step, the method includes a through processing step of forming a through hole penetrating the build-up layer and the flexible rigid printed wiring board. The residue after the process may be treated with the same chemical at once.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, some embodiments of the present invention will be described with reference to the drawings. Note that each embodiment is merely an example, and the present invention is not limited to these embodiments.
[0023]
<First embodiment>
FIG. 3 is a cross-sectional view showing one step of the method for manufacturing a flexible rigid build-up wiring board according to the present invention. In the present embodiment, a flexible rigid build-up wiring board similar to the flexible rigid build-up wiring board shown in FIG. 1 is manufactured.
[0024]
First, a flexible rigid printed wiring board 20 is prepared. The flexible rigid printed wiring board 20 is provided with a conductor 21b on each side of a base film 21a to form an FPC base 21, and a film coverlay 22 mainly composed of a polyimide resin is laminated on each side of the FPC base 21; A glass epoxy resin layer 24 is laminated on each of the film cover lays 22 with an adhesive layer 23 interposed therebetween with the central portion of each of the film cover lays 22 exposed.
[0025]
Here, the portion of the glass epoxy resin layer 24 corresponding to the FPC cable portion of the flexible rigid printed wiring board 20 is pierced by a mold or a router before lamination. A region 28 indicated by a chain line in FIG. 3 corresponds to a hollow portion of the glass epoxy resin layer 24. FIG. 4 shows a plan view of the glass epoxy resin layer 24. As described above, the region 28 located on the FPC cable in the glass epoxy resin layer 24 is processed and removed before being laminated on the FPC substrate 21.
[0026]
After forming the flex-rigid printed wiring board 20, a circuit is formed on the surface of each glass epoxy resin layer 24 by the conductor 25.
[0027]
Next, the build-up layer 27 is formed by RCC made of a build-up resin and a copper foil. Before the build-up layer 27 is laminated, a portion corresponding to the FPC cable portion is cut out with a mold. A region 29 shown by a dotted line in the cross-sectional view of FIG. 3 corresponds to a portion where the build-up layer 27 has been penetrated. FIG. 5 shows a plan view of the build-up layer 27. FIG. As described above, the region 29 located on the FPC cable in the build-up layer 27 is processed and removed before lamination on the flexible rigid printed wiring board 20. Then, a second laminating step of laminating the mold-processed build-up layer 27 on the flex-rigid printed wiring board 20 is performed.
[0028]
By removing the region 29 in advance, it is possible to reduce resin waste generated when performing the FPC processing later. In addition, the processing time of the build-up layer 27 can be shortened because the processing can be performed instantaneously with the mold.
[0029]
As a material of the build-up layer 27, a low flow type resin can be adopted. Therefore, the resin flow on the FPC cable portion observed in the build-up layer in the related art does not occur. Further, at this stage, since the FPC cable portion is in an exposed state, there is no need to perform any work of peeling off the build-up layer on the FPC portion in a later step, and the processing time and cost can be reduced.
[0030]
After laminating the build-up layer 27, a blind via hole 30 having a diameter of about 70 to 150 μm is formed in the rigid portion 27a of the build-up layer 27 by laser processing. For this laser processing, a carbon dioxide laser processing apparatus is used, and the laser conditions are set to 2 in a cycle mode in which via shape defects due to heat of fusion in the via holes are small so that the reliability of the blind via holes 30 can be sufficiently ensured. Shot processing. After the laser processing step, for a product with a through-hole specification, NC processing is subsequently performed to form a predetermined through-hole 31.
[0031]
Thereafter, a chemical solution treatment for removing the resin residue at the interlayer connection portion is performed. In this chemical solution treatment step, the resin residue at the bottom of the blind via hole 30 and the smear in the layer of the through hole 31 that have been treated in the laser processing step are removed. At that time, by optimizing the laser condition and the drill condition of the through hole, both portions can be processed by the same chemical liquid treatment. As the chemical treatment, desmear treatment with permanganate is effective.
[0032]
After the chemical treatment step, collective copper plating of the blind via hole 30 and the through hole 31 is performed. Then, the circuit formation, the solder resist formation, and the surface treatment of the outermost layer portion 32 are sequentially performed to complete the flexible rigid printed wiring board.
[0033]
Hereinafter, other embodiments of the present invention will be described. In each of the embodiments, the glass epoxy resin layer 24 and the build-up layer 27 are each cut through before lamination. Hereinafter, only differences from the first embodiment will be described. The cross section of one step of the manufacturing method of each embodiment is the same as that of FIG.
[0034]
<Second embodiment>
In the present embodiment, router processing is employed for a process of penetrating the build-up layer 27 before lamination on the flex-rigid printed wiring board 20. In the die processing employed in the first embodiment, cracks may occur in the resin around the processed part. FIG. 6 shows this state. By employing the router processing, the mechanical stress on the build-up layer 27 is reduced, and the crack 32 is not generated. In particular, in the case of a product in which the build-up layer 27 is processed into a complicated shape, the method of the present embodiment is effective.
[0035]
<Third embodiment>
In the present embodiment, the build-up layer 27 is an RCC in which a build-up resin and a copper foil are laminated. In the manufacturing method of the present embodiment, since the anchor effect between the resin and the copper foil is strong, the reliability of the beer strength when the copper foil is peeled increases. On the other hand, since the laser processing is based on the conformal method, the number of steps for mask etching of the copper foil in advance is increased.
[0036]
<Fourth embodiment>
In the present embodiment, the build-up layer 27 is manufactured by performing a chemical treatment on the build-up resin and performing copper plating. Specifically, the build-up resin is subjected to a chemical treatment such as desmear permanganate, and the resin is provided with irregularities, followed by copper plating. Therefore, the peel strength between the resin and the copper plating tends to be lower than that of the RCC. However, since laser processing can process a resin by a direct method, workability is easier than a conformal method, and a mask etching step is not required.
[0037]
<Fifth embodiment>
In the present embodiment, the blind via holes 30 and the through holes 31 are separately subjected to chemical treatment. This embodiment is adopted when the amount of resin remaining after the laser processing of the blind via hole 30 is different from the amount of smear of the through hole 31.
[0038]
As a manufacturing process, after the blind via hole 30 is laser-processed, the resin residue at the bottom of the via of the blind via hole 30 is immediately removed by a chemical treatment mainly using a permanganate solution. At this stage, since the FPC cable 26 is similarly violated, the chemical solution processing is performed while controlling the FPC cable 26 to be eliminated and the circuit 21b not to be exposed. Thereafter, the through hole 31 is formed by NC processing. Then, a chemical treatment is performed again using the permanganate solution as a center. The chemical treatment condition at this time is a condition that has both removal of smear from the through-holes 31 and prevention of exposure of the FPC cable portion 26.
[0039]
<Sixth embodiment>
In the present embodiment, only the blind via hole 30 is treated with a chemical solution. This process is performed under an optimum condition using a chemical solution centered on a permanganate solution to prevent the exposure of the FPC cable portion 26 and the amount of resin remaining at the bottom of the blind via hole 30.
[0040]
【The invention's effect】
In a method of manufacturing a flexible rigid build-up wiring board on which a build-up layer is laminated, such that a part thereof is exposed on the flexible rigid printed wiring board, as in the present invention, before lamination to the flexible rigid printed wiring board, A processing step of processing the build-up layer to remove a portion corresponding to an exposed portion of the flexible rigid printed wiring board, a laminating step of laminating the build-up layer on the flexible rigid printed wiring board, and an interlayer connection. By including a laser processing step of processing the build-up layer with a laser and a chemical processing step of removing residues after the laser processing with a chemical, a part of the build-up layer can be removed from the flexible rigid printed wiring board. Eliminates the need for a stripping step, improving manufacturing efficiency , There is no possibility of damage to the cable portion, a flexible rigid build-up wiring board having high reliability can be obtained. In addition, a general low-flow resin can be used for the build-up layer, and the formation of blind via holes and through-holes is easy.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a flexible rigid build-up wiring board.
FIG. 2 is a schematic sectional view showing a conventional manufacturing method.
FIG. 3 is a schematic sectional view of a flexible rigid build-up wiring board showing a manufacturing method according to each embodiment of the present invention.
FIG. 4 is a schematic plan view showing a glass epoxy resin layer processing step in the manufacturing method of each embodiment.
FIG. 5 is a schematic plan view showing a build-up layer processing step in the manufacturing method of each embodiment.
FIG. 6 is a schematic plan view showing a state in which a crack has occurred in a build-up layer.
[Explanation of symbols]
10, 20 Flexible rigid printed wiring board 11a, 21a Base film 11b, 21b Conductor 12, 22 Film cover lay 13, 23 Adhesive layer 14, 24 Glass epoxy resin layer 15, 25 Inner layer conductor 16, 26 FPC cable connection part 17, 27 Build-up layer 18 Outer layer conductors 19, 30 Blind via hole 28 Glass epoxy resin layer cut-out part 29 Build-up layer cut-out part 31 Through through hole 32 Resin crack of build-up layer

Claims (6)

A method for manufacturing a flexible rigid build-up wiring board in which a build-up layer is laminated, such that a part thereof is exposed on the flexible rigid printed wiring board,
A processing step of processing the build-up layer before lamination on the flexible rigid printed wiring board, and removing a part corresponding to an exposed part of the flexible rigid printed wiring board,
A laminating step of laminating a build-up layer on a flexible rigid printed wiring board, a laser processing step of processing the build-up layer with a laser for interlayer connection,
A chemical solution treatment step of removing a residue after the laser processing step with a chemical solution. A method for manufacturing a flexible rigid build-up wiring board. 2. The method for manufacturing a flexible rigid build-up wiring board according to claim 1, wherein in the removing step, a portion of the build-up layer is removed by die processing. 2. The method for manufacturing a flexible rigid build-up wiring board according to claim 1, wherein in the removing step, a portion of the build-up layer is removed by router processing. The method for manufacturing a flexible rigid build-up wiring board according to claim 1, wherein the build-up layer is formed by providing a metal foil on the low-fluidity insulating resin layer. 2. The method for manufacturing a flexible rigid build-up wiring board according to claim 1, wherein the build-up layer is manufactured by applying metal plating to an insulating resin layer having low fluidity. After the laminating step and before the chemical processing step, the method includes a penetrating processing step of forming a through hole penetrating the build-up layer and the flexible rigid printed wiring board. 2. The method for manufacturing a flexible rigid build-up wiring board according to claim 1, wherein the remaining residue is treated at once with the same chemical solution.

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