JP2018085362A - Wiring board and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board by which the variation in the circuit width of a wiring pattern in a thickness direction can be reduced as compared to that in the past; and a method for manufacturing the wiring board.SOLUTION: A method for manufacturing a wiring board 10 according to the present invention comprises the steps of: preparing a metal layer 54 laminated on a support plate 50; performing a preceding stage of etching which includes the steps of partially covering an F-face 54F of the metal layer 54 with a first etching resist layer 55 having a first pattern 55A, and removing the metal layer 54 to a position halfway across its thickness in a thickness direction; and performing a later stage of etching which includes the steps of laminating an insulator layer 15 on the metal layer 54 from the side of the F-face 54F thereof, removing the support substrate 50, partially covering an S-face 54S of the metal layer 54, which is a face on the side where the support plate 50 is removed, with a second etching resist 56 having a first pattern 56A, and removing wholly the metal layer from the S-face 54S in the thickness direction, whereby a wiring pattern 21 is thus formed from the metal layer 54.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a wiring board having a wiring pattern formed by etching a metal layer and a wiring board.

  As a method for manufacturing this type of wiring board, a method is known in which a metal layer on an insulating substrate is partially covered with an etching resist having a predetermined pattern and etched to form a predetermined wiring pattern from the metal layer (for example, Patent Document 1).

JP2008-098406 (paragraph [0019], FIG. 1)

  By the way, in the manufacturing method of the above-mentioned wiring board, the side of each electric circuit constituting the wiring pattern is exposed to the etching solution longer as the position is closer to the etching resist. As a result, there may be a problem that a difference occurs in the electric circuit width of the wiring pattern in the thickness direction of the wiring pattern. Further, it is considered that the thicker the wiring pattern, the larger the difference in the electric circuit width of the wiring pattern, and the greater the problem.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wiring board and a method for manufacturing the wiring board that can suppress a difference in electric circuit width in the thickness direction of the wiring pattern.

  A method for manufacturing a wiring board according to the present invention is the method for manufacturing a wiring board having a wiring pattern formed by etching a metal layer, and preparing the metal layer laminated on a support plate; Of these, the first surface opposite to the support plate is partially covered with a first etching resist having a first pattern, and the portion of the metal layer not covered with the first etching resist is A pre-etching process for etching from one surface to a middle position in the thickness direction, and removing the first etching resist from the metal layer, and burying the metal layer from the first surface to the middle position in an insulating resin layer And removing the support plate from the metal layer, and forming a second surface, which is a surface of the metal layer on which the support plate is removed, on the first pattern same as the first etching resist. Part of the metal layer is covered with a second etching resist, and a part of the metal layer that is not covered with the second etching resist is etched from the second surface side to the intermediate position, and the metal layer And a post-etching process for forming the wiring pattern of the first pattern and removing the second etching resist from the metal layer.

  The wiring board according to the present invention is a wiring board in which at least a part of a wiring pattern is buried in an insulating resin layer, and the wiring pattern includes an intermediate metal layer located in an intermediate portion in the thickness direction, The intermediate metal layer includes a pair of main metal layers that are laminated on both sides of the front and back surfaces, have different etching characteristics from the intermediate metal layer, and are thicker than the intermediate metal layer.

Side sectional view of the wiring board according to the first embodiment of the present invention. Side cross-sectional view showing the state of use of the wiring board Side sectional view showing the manufacturing process of the wiring board Side sectional view showing the manufacturing process of the wiring board Side sectional view showing the manufacturing process of the wiring board Side sectional view showing the manufacturing process of the wiring board Side sectional view of a wiring board according to a second embodiment of the present invention. Side sectional view showing the manufacturing process of the wiring board Side sectional view of a wiring board according to a third embodiment of the present invention. Side sectional view showing the manufacturing process of the wiring board Side sectional view showing the manufacturing process of the wiring board

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the wiring board 10 of the present embodiment includes a wiring pattern 21 inside an insulating substrate 20. The wiring pattern 21 has a plurality of electric paths 11 extending in parallel, for example. FIG. 1 shows a cross section of the wiring board 10 orthogonal to the electric circuit 11.

  The insulating substrate 20 is formed by bonding a pair of insulating resin layers 15 and 16 having substantially the same thickness. The pair of insulating resin layers 15 and 16 are prepregs obtained by impregnating a woven fabric of reinforcing fibers (for example, glass cloth) with a resin. The insulating substrate 20 has a thickness of, for example, about 50 to 500 [μm].

  The wiring pattern 21 is sandwiched between a pair of insulating resin layers 15 and 16. The wiring pattern 21 has a three-layer structure, and the main metal layer 13 (hereinafter referred to as appropriate) embedded in one insulating resin layer 15 (hereinafter referred to as “front-side insulating resin layer 15” as appropriate). (Referred to as “front-side main metal layer 13”), a main metal layer 14 embedded in the other insulating resin layer 16 (hereinafter referred to as “back-side main metal layer 14” as appropriate), and both the main metal layers 13 , 14 and the intermediate metal layer 12.

  Both the main metal layers 13 and 14 have a thickness of, for example, 25 to 200 [μm], and the intermediate metal layer 12 has a thickness of, for example, 0.1 to 1.0 [μm]. Thus, the intermediate metal layer 12 is extremely thin compared to the two main metal layers 13 and 14. The intermediate metal layer 12 is embedded in the insulating resin layer 16 on the back side, and the boundary surface 12K between the intermediate metal layer 12 and the main metal layer 13 on the front side is separated from the boundary surface 20K between the both insulating resin layers 15 and 16. It is arranged substantially flush. The main metal layers 13 and 14 do not necessarily have the same thickness.

  Both the main metal layers 13 and 14 are made of, for example, the same metal, and the intermediate metal layer 12 is made of a metal having etching characteristics different from those of the main metal layers 13 and 14. Specifically, the intermediate metal layer 12 is made of a metal having higher acid resistance than the main metal layers 13 and 14, for example, the main metal layers 13 and 14 are made of copper, whereas the intermediate metal layer 12 is made of copper. Is made of, for example, nickel, which has higher acid resistance than copper.

  The main metal layers 13 and 14 are wider than the thickness. Further, both side surfaces of the main metal layers 13 and 14 are curved in a concave shape, and the cross section of the main metal layers 13 and 14 has a substantially trapezoidal shape whose width suddenly expands on the intermediate metal layer 12 side.

  FIG. 2 shows an example of use of the wiring board 10. The wiring board 10 has a structure having insulating layers 17 and 17 on both front and back surfaces, and conductor circuit layers 25 and 25 are formed on the insulating layers 15, 16 and 17. And the via | veer 26 which connects between the conductor circuit layers 25 and 25 and between the conductor circuit 25 and the wiring pattern 21 is formed. Further, a through hole 27 penetrating the wiring board 10 is formed, and the through hole 27 and the conductor circuit layer 25 are connected to be used as a signal circuit. Solder resist layers 28 and 28 are formed on the outermost conductor circuits 25 and 25. A plurality of pad holes are formed in the solder resist layer 28, and a part of the conductor circuit layer 25 is a pad hole. A pad 26 is located inside. Then, an electronic component 90 such as an IC is connected via a solder bump 19 formed on each pad 26.

Next, the manufacturing method of the wiring board 10 of this embodiment is demonstrated.
(1) As shown in FIG. 3 (A), first main metal layers 51, 51 made of copper are laminated on an F surface 50F that is a front surface of the support plate 50 and an S surface 50S that is a rear surface. A laminated plate 59 is prepared. The support plate 50 is formed by laminating copper foils 50B on both front and back surfaces of the insulating layer 50A, and the copper foil 50B of the support plate 50 and the first main metal layer 51 are connected only to the outer edge portion (not shown). This part is easily separable. The first main metal layer 51 is a copper foil or electrolytic copper plating having a thickness of 25 to 200 [μm].

  Here, since the same processing is performed on the first main metal layer 51 on the F surface 50F side of the support plate 50 and on the first main metal layer 51 on the S surface 50S side, hereinafter, on the F surface 50F side. An explanation will be given by taking the first main metal layer 51 as an example.

  (2) As shown in FIG. 3B, the intermediate metal layer 52 is formed on the first main metal layer 51 of the laminated plate 59. The intermediate metal layer 52 is formed by plating or sputtering. The intermediate metal layer 52 is preferably formed by nickel plating. The thickness of the intermediate metal layer 52 is about 0.1 to 1.0 [μm].

  (3) As shown in FIG. 3C, the second main metal layer 53 is formed on the intermediate metal layer 52. The second main metal layer 53 is formed of a metal having the same etching characteristics as that of the intermediate metal layer 52 and is formed to have substantially the same thickness as the intermediate metal layer 52. As described above, the metal layer 54 including the first main metal layer 51, the intermediate metal layer 52, and the second main metal layer 53 is formed and supported by the support plate 50.

  (4) As shown in FIG. 4A, an F surface 54F (corresponding to the “first surface” of the present invention) on the opposite side of the support plate 50 in the metal layer 54 is the main metal layer 13 on the front side. Is partially covered with a first etching resist 55 having a first pattern 55A for forming the.

  (5) A first etching process is performed on the metal layer 54. In the first etching process, the second main metal layer 53 dissolves, but the intermediate metal layer 52 uses an etchant that is difficult or impossible to dissolve. As a result, as shown in FIG. 4B, only the second main metal layer 53 of the metal layer 54 is etched, and the periphery of the first pattern 55A is removed from the F surface 54F to an intermediate position in the thickness direction. Thus, the main metal layer 13 on the front side is formed from the second main metal layer 53.

  (6) As shown in FIG. 4C, the first etching resist 55 is removed.

  (7) As shown in FIG. 5A, the insulating resin layer 15 on the front side is laminated on the metal layer 54 and heated and pressed. Thereby, the main metal layer 13 on the front side is buried in the insulating resin layer 15 on the front side.

  (8) As shown in FIG. 5B, the outer edge portion connecting the support plate 50 and the first main metal layer 51 is cut, and the support plate 50 (including the copper foil 50B) is removed. Thereafter, the front insulating resin layer 15 functions as a carrier and an etching resist in a second etching process to be described later.

  (9) As shown in FIG. 5C, the S surface 54S (corresponding to the “second surface” of the present invention) which is the surface of the metal layer 54 from which the support plate 50 has been removed is the back side. It is partially covered with a second etching resist 56 having a first pattern 56A for forming the main metal layer 14.

  (10) A second etching process is performed on the metal layer 54. In the second etching process, the first main metal layer 51 dissolves, but the intermediate metal layer 52 uses an etchant that is difficult or impossible to dissolve. As a result, as shown in FIG. 6A, only the first main metal layer 51 of the metal layer 54 is etched, and the periphery of the first pattern 55A is removed from the F surface 54F to a middle position in the thickness direction. The back side main metal layer 14 is formed from the first main metal layer 51.

  (11) A third etching process is performed on the metal layer 54. In the third etching process, the intermediate metal layer 52 is dissolved, but the first main metal layer 51 and the second main metal layer 53 use an etchant that is difficult or impossible to dissolve. 6B, only the intermediate metal layer 52 of the metal layer 54 is etched and exposed from the first main metal layer 51 and the second main metal layer 53 of the intermediate metal layer 52. A part is removed, and the plurality of electric paths 11 are formed in a state separated from each other. Then, the second etching resist 56 is removed, and the wiring pattern 21 is completed.

  (12) As shown in FIG. 6C, the insulating resin layer 16 on the back side is laminated on the second main metal layer 53 side of the wiring pattern 21 and heated and pressed. Thus, the wiring board 10 shown in FIG. 1 is completed.

  The description regarding the manufacturing method of the wiring board 10 of this embodiment is above. In the present embodiment, the first etching process described above corresponds to the “pre-stage etching process” according to the present invention, and the second and third etching processes correspond to the “post-stage etching process” according to the present invention. In addition, the third etching process may be performed between the above-described steps (5) and (6). In that case, the first and third etching processes are the “pre-stage etching process” according to the present invention. Correspondingly, the second etching process corresponds to the “rear etching process” according to the present invention.

  Next, the effect of the manufacturing method of the wiring board 10 of this embodiment is demonstrated. As described above, in the method of manufacturing the wiring board 10 of the present embodiment, the etching process for the metal layer 54 for forming the wiring pattern 21 includes the etching process from the front side of the metal layer 54 and the etching process from the back side. It is divided into two. Thereby, compared with the conventional manufacturing method which etches the metal layer 54 only from one side of the front and back, the width difference of the electric circuit 11 in the thickness direction of the wiring pattern 21 (the bottom width W2 and the top width W1 in FIG. 1). Difference). Further, since an increase in the magnitude difference of the electric circuit width when the wiring pattern 21 is thickened can be suppressed, it is possible to allow a large current to flow. That is, the current of the wiring board 10 can be increased. Furthermore, since the amount of overhang of the maximum width portion of each electric circuit 11 can be suppressed, the electric circuits 11 and 11 can be arranged close to each other, and thus the wiring pattern 21 can be refined. Moreover, in the wiring board 10 of this embodiment, the intermediate metal layer 12 having different etching characteristics from the other portions is provided in the intermediate portion of the wiring pattern 21 in the thickness direction. In addition, the boundary position between the etching process from the front side and the etching process from the back side of the metal layer 54 is stabilized, and the shape quality of the cross section of the wiring pattern 21 is also stabilized.

[Second Embodiment]
As shown in FIG. 7, the wiring pattern 21 </ b> V of the wiring board 10 </ b> V of the present embodiment is obtained from the first electric circuit 11 in addition to the electric circuit 11 described in the first embodiment (hereinafter referred to as “first electric circuit 11”). The second embodiment differs from the first embodiment in that the second and third electric circuits 11B and 11C having a small thickness are provided. The second electric circuit 11B is composed of only the main metal layer 13 on the front side, whereas the third electric circuit 11C is composed of only the main metal layer 14 and the intermediate metal layer 12 on the back side. The back side main metal layer 14 is thinner than the front side main metal layer 13. Hereinafter, the method of manufacturing the wiring board 10V of the present embodiment will be described mainly with respect to differences from the first embodiment.

  (1) After the step (3) in the manufacturing method of the first embodiment, as shown in FIG. 8A, the main metal on the front side of the first electric circuit 11 is formed on the F surface 54F of the metal layer 54. A first etching resist 55V having a first pattern 55A for forming the layer 13 and a second pattern 55B for forming the main metal layer 13 on the front side of the second electric circuit 11B is overlaid.

  (2) Steps similar to the steps (5) to (8) in the manufacturing method of the first embodiment are performed, and as shown in FIG. A main metal layer 13 on the front side of the first and second electric paths 11 and 11B is formed.

  (3) As shown in FIG. 8B, a first pattern 56A for forming the main metal layer 14 on the back side of the first electric circuit 11 on the S surface 54S of the metal layer 54, and a third electric circuit A second etching resist 56V having a second pattern 56C for forming the main metal layer 14 on the back side of 11B is overlaid.

  (4) Steps similar to the steps (10) to (12) in the manufacturing method of the first embodiment are performed, and the first and first surfaces are formed on the S surface 54S of the metal layer 54 as shown in FIG. The main metal layer 14 on the back side of the three electric circuits 11 and 11C is formed, and the insulating resin layer 16 on the back side is laminated to complete the wiring board 10V.

  This completes the description of the structure and manufacturing method of the wiring board 10V of the present embodiment. According to the method for manufacturing the wiring board 10V of the present embodiment, the first to third electric circuits 11, 11B, and 11C having different cross-sectional areas can be easily formed in one wiring pattern 21V. And according to the size of the cross-sectional area, the first to third electric paths 11, 11B, 11C can be selectively used for control and power, or can be used separately for a large current system and a small power system.

  Further, by making the main metal layer 14 on the back side thinner than the main metal layer 13 on the front side, the third electric circuit 11C is formed with a fine pitch electric circuit as compared with the first electric circuit 11 and the second electric circuit 11B. Can do.

[Third Embodiment]
As shown in FIG. 9, the wiring board 10 </ b> Z of the third embodiment has two wiring patterns 21 </ b> X and 21 </ b> Y stacked in an insulating substrate 20 </ b> Z. The wiring patterns 21X and 21Y have the same structure as the wiring pattern 21 of the first embodiment in the cross-sectional shape of FIG.

  In detail, the insulating substrate 20Z of the wiring board 10Z of the present embodiment is formed by laminating outer insulating resin layers 32 and 33 on both sides of the front and back of the intermediate insulating resin layer 31, and one wiring pattern 21X is formed of an intermediate insulating resin. The other wiring pattern 21 </ b> Y is sandwiched between the intermediate insulating resin layer 31 and the other outer insulating resin layer 33. The intermediate insulating resin layer 31 corresponds to the “front insulating resin layer 15” in the first embodiment, and the outer insulating resin layers 32 and 33 correspond to the “back insulating resin layer 16” in the first embodiment. Equivalent to. The intermediate metal layer 12 of one wiring pattern 21X is buried in one outer insulating resin layer 32, and the intermediate metal layer 12 of the other wiring pattern 21Y is buried in the other outer insulating resin layer 33. Hereinafter, with respect to the method for manufacturing the wiring board 10Z of the present embodiment, differences from the first embodiment will be mainly described.

  (1) First and second laminated plates 61 and 62 having the same structure as that of one side of the laminated plate 59 (see FIG. 3A) described in the first embodiment are prepared, and the first embodiment is manufactured. As shown in FIG. 10A, only the second main metal layer 53 in the first and second laminated plates 61 and 62 is etched by the same steps as the steps (1) to (6) in the method. The main metal layer 13 on the front side of both the wiring patterns 21X and 21Y is formed.

  (2) As shown in FIG. 10 (A), a prepreg is disposed between the first and second laminated plates 60, 61, and the main side of the front side of the first and second laminated plates 60, 61 is arranged in the prepreg. The metal layers 13 are pressed and stacked, and heated and pressed (see FIG. 10B).

  (3) As shown in FIG. 11A, the support plate 50 is removed from the first first laminated plate 61.

  (4) As shown in FIG. 11B, the metal layer 54 of the first first laminated plate 61 is partially covered with the second etching resist 56 as in the step (9) in the manufacturing method of the first embodiment. Covered.

  (5) Steps similar to the steps (10) to (12) in the manufacturing method of the first embodiment are performed, and the metal layer 54 and the intermediate metal layer 12 of the first laminated plate 61 are etched. 11C, one wiring pattern 21X is completed and covered with the outer insulating resin layer 32.

  (6) As shown in FIG. 11C, the support plate 50 of the second laminated plate 62 is removed.

  (7) Next, steps similar to the steps (9) to (12) in the manufacturing method of the first embodiment are performed, and the metal layer 54 and the intermediate metal layer 12 of the second laminated plate 62 are etched. The other wiring pattern 21Y is completed and covered with the outer insulating resin layer 33. Thereby, the wiring board 10Z of this embodiment shown in FIG. 9 is completed.

  This completes the description of the structure and manufacturing method of the wiring board 10Z of the present embodiment. According to the manufacturing method of the present embodiment, it is possible to easily manufacture the wiring board 10Z including the plurality of wiring patterns 21X and 21Y.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various modifications are possible within the scope of the invention other than the following. It can be changed and implemented.

  (1) Although the intermediate metal layer 52 is provided in each of the wiring boards 10, 10 </ b> V, and 10 </ b> Z of each of the embodiments, a configuration in which the intermediate metal layer 52 is not provided may be employed. That is, the metal layer 54 may have a single-layer structure of the same metal, and the metal layer 54 may be divided into a front-stage etching process from the front side and a rear-stage etching process from the back side. In this case, it is only necessary to etch about half of the front side and about half of the back side of the metal layer 54 by time management.

  (2) Further, the metal layer 54 is constituted by the first and second main metal layers having different etching characteristics, with the half of the thickness of the metal layer 54 and the remaining half of the metal layer 54 not provided with the intermediate metal layer 52. In the first-stage etching process, the first main metal layer is dissolved, but the second main metal layer is dissolved in an etching solution that is difficult or impossible to dissolve, and in the second-stage etching process, the second main metal layer is dissolved. However, the wiring pattern 21 may be formed from the metal layer 54 by using an etchant that is difficult or impossible to dissolve the first main metal layer.

10, 10V, 10Z Wiring board 11, 11B, 11C Electric circuit 12, 52 Intermediate metal layer 13, 14 Main metal layer 15, 16 Insulating resin layer 21, 21V, 21X, 21Y Wiring pattern 31 Intermediate insulating resin layer 32, 33 Outside insulation Resin layer 51 First main metal layer 52 Intermediate metal layer 53 Second main metal layer 54 Metal layer 55, 55V First etching resist 55A, 56A First pattern 55B, 56C Second pattern 56, 56V Second etching resist

Claims (13)

In a method for manufacturing a wiring board having a wiring pattern formed by etching a metal layer,
Providing the metal layer laminated on a support plate;
Partially covering a first surface of the metal layer opposite to the support plate with a first etching resist having a first pattern;
A pre-etching process for etching a portion of the metal layer that is not covered with the first etching resist from the first surface to an intermediate position in the thickness direction;
Removing the first etching resist from the metal layer and burying the metal layer from the first surface to the middle position in an insulating resin layer;
The support plate is removed from the metal layer, and the second surface, which is the surface of the metal layer from which the support plate has been removed, is a second etching resist having the same first pattern as the first etching resist. Partially covering,
A post-etching process in which a portion of the metal layer that is not covered with the second etching resist is etched from the second surface side to the middle position to form the wiring pattern of the first pattern from the metal layer. When,
Removing the second etching resist from the metal layer. In the manufacturing method of the wiring board of Claim 1,
As the metal layer, a layer formed by laminating a pair of main metal layers having different etching characteristics from the intermediate metal layer on both sides of the front and back of the intermediate metal layer,
The pre-stage etching process or the post-stage etching process includes an intermediate layer etching process that etches the main metal layer and then changes the etchant to etch the intermediate metal layer. In the manufacturing method of the wiring board of Claim 2,
A second pattern that covers a portion of the metal layer that is not covered by the other etching resist is provided in one of the first etching resist or the second etching resist, and the wiring pattern of the first pattern The wiring pattern of the thin second pattern is formed. In the manufacturing method of the wiring board of Claim 2,
The main metal layer laminated on the front side of the intermediate metal layer and the main metal layer laminated on the back side of the intermediate metal layer are different in thickness. In the manufacturing method of the wiring board of any one of Claims 1 thru | or 4,
The insulating resin layer is sandwiched between the first surfaces of the pair of metal layers after the removal of the first etching resist, and the second surfaces of the pair of metal layers are respectively made of the second etching resist. Then, the latter etching process is performed. In the manufacturing method of the wiring board as described in any one of Claims 1 thru | or 5,
The intermediate position when the metal layer is etched from the first surface to an intermediate position in the thickness direction is set to a substantially central position in the thickness direction of the metal layer. In the manufacturing method of the wiring board as described in any one of Claims 1 thru | or 6,
The wiring pattern is formed so as to be widest at the middle position in the thickness direction of the metal layer and gradually become narrower toward the first surface and the second surface. A method of manufacturing a wiring board according to any one of claims 1 to 7,
The support plate is removed after the metal layer is buried in the insulating resin layer from the first surface to the middle position. A method for manufacturing a wiring board according to any one of claims 1 to 8,
The support plate has a thickness of 50 μm or more. A method for manufacturing a wiring board according to any one of claims 1 to 9,
The metal layer is laminated on both sides of the support plate. A wiring board in which at least a part of the wiring pattern is buried in the insulating resin layer,
The wiring pattern includes a pair of intermediate metal layers positioned in the middle part in the thickness direction, laminated on both sides of the front and back surfaces of the intermediate metal layer, and different in etching characteristics from the intermediate metal layer and thicker than the intermediate metal layer. The main metal layer. The wiring board according to claim 10, wherein
The pair of main metal layers become narrower as the distance from the intermediate metal layer increases. The wiring board according to claim 11 or 12,
The main metal layer laminated on the front side of the intermediate metal layer and the main metal layer laminated on the back side of the intermediate metal layer are different in thickness.

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