JPH07249855A - Printed wiring board and its manufacture - Google Patents

Abstract

PURPOSE:To keep a printed wiring board high in performance and quality for a long time by a method wherein an upper metal layer close to an upper layer is set to have a larger ionization tendency than a lower metal layer close to a lower layer. CONSTITUTION:An upper layer 322 of metal (Ni or the like) out of two adjacent metal layers 321 and 322 and close to an upper layer 33' is set to have a larger ionization tendency than a lower layer 321 of metal (Pd or the like) close to a lower layer 31. Therefore, even if corrosion advances in the upper layer 322 of metal (Ni), the lower layer 321 of metal (Pd) hardly corrodes. By this setup, even if the upper layer 33 of expensive precious metal is set thin, it can be kept high in corrosion resistance, so that a printed wiring board of this constitution can be kept high in performance and quality for a long term.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a method for manufacturing the printed wiring board. More specifically, it can be manufactured inexpensively and efficiently, and can maintain high performance and quality for a long period of time. The present invention relates to a printed wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, in a manufacturing process of a printed wiring board (hereinafter referred to as "wiring board"), a substrate for printed wiring board ( Hereinafter, a "wiring board base material") is often subjected to plating after appropriately forming a pattern that finally becomes a conductive (conducting) circuit or the like. For example, as shown in FIG. 1, a predetermined wiring board substrate (however,
The figure shows the base material for one piece of the final product. ) 1
After forming a predetermined conductive pattern (portion) 2, the conductive pattern 2 is covered with a predetermined plated portion (layer) 3.

By the way, the thickness of the plated portion (layer) 3 is often appropriately selected according to the application of the wiring board. For example, for a wiring board used for a disposable IC card such as a telephone card, it is sufficient to form a relatively thin plated portion of about 0.1 μm, but it is repeatedly used like a bank cash card. In a wiring board used for an IC card or the like, a plated portion having a thickness of 1 μm or more is often formed in order to maintain the performance and quality of the final product for a long time. On the other hand, these plated parts
Exposed on the surface of the final product (IC card etc.),
Since it is the contact surface with other equipment (for example, the reader of a reader), it is required to have particularly excellent wear resistance, corrosion resistance, and electrical conductivity, and particularly good solder processability. If it is a part to be
It is desired to form it from a noble metal such as u, Pt, or Rh.

However, if the entire thick plated portion as described above is formed of an expensive precious metal such as Au in accordance with this request, the manufacturing cost of the wiring board will increase. In addition, in recent years, due to a demand for improvement in manufacturing efficiency and the like, a long-sized wiring board substrate as shown in FIG. After the conductive pattern 2 is continuously formed on L, a plating portion is continuously formed while continuously passing through the plating solution 82 as shown in FIG. "Reel-to-reel method" plating is often performed, but with this method, it is difficult to form a thick plated part made of a noble metal such as Au at once.

Therefore, as shown in FIG. 9, the above-mentioned thick plated portion, which is required to have particularly excellent characteristics, is brought into direct contact with the surface of the conductive pattern 2d, and is relatively coated with Ni or the like. Relatively thin (thickness of about 0.9 to 2.7 μm in the case of the cash card) of the underlayer 31d formed of an inexpensive metal, and relatively thin formed of a noble metal such as Au for covering the underlayer. (0.05 for the same card
~ 0.15 μm thick upper layer (surface layer) 33d
And is formed separately. By using the plated portion 3d having such a multi-layer structure, the amount of precious metal used can be reduced, the manufacturing cost can be reduced, and the portion composed of the precious metal can be thin. The "reel system" can also be used for easy plating.

[0006]

However, when this relatively thin upper layer 33d is made of a relatively porous precious metal such as Au (a film or the like, it is a metal that easily causes (pinhole) pores). To use. ],
Pinholes h often exist in the same layer 33d. Then, water drops, moisture, user's sweat, etc. (those that act with the oxidant in a corrosive environment) enter such pinholes h,
When reaching the underlayer 31d, as shown in FIG. 9, the corrosion of the same layer 31d progresses due to the effect of the corrosion battery (local battery) (the upper layer 33d becomes the cathode portion, the underlayer 31d becomes the anode portion, and the lower layer 31d becomes the lower portion). Corrosion (dissolution) of the stratum 31d will progress], and eventually the conductive pattern (part) 2d will also corrode (in addition to this type of corrosion, oxygen, hydrogen sulfide, etc. will enter the pinholes and cause corrosion ( Therefore, it is often difficult to use a wiring board having such a plated portion 3d for a long period of time while maintaining high performance and quality.

On the other hand, by increasing the thickness of the upper layer 33d made of the above-mentioned porous precious metal, it is possible to suppress the generation of the pinhole h or to reduce the hole diameter of the hole h. As described above, an increase in the amount of precious metal used causes a rise in the manufacturing cost, and it is difficult to apply the "reel-to-reel system".

The present invention solves the above problems and provides a wiring board which can be manufactured inexpensively and efficiently, and which can maintain high performance and quality for a long period of time, and a manufacturing method thereof. To aim.

[0009]

A wiring board according to the first aspect of the present invention comprises a film-shaped wiring board base material, a conductive pattern portion formed on at least one of the front and back surfaces of the wiring board base material, and In a wiring board including a plated portion that covers the conductive pattern portion, the plated portion is provided with an underlayer disposed at a position in direct contact with the surface of the conductive pattern, and a surface and a surface side portion of the plated portion. A multilayer structure comprising an upper layer made of a noble metal and an intermediate layer formed of two or more metal layers, which is arranged in a portion sandwiched by the underlayer and the upper layer, and the intermediate layer is Of at least one set of two adjacent metal layers among the metal layers to be formed, the ionization tendency of the metal forming the upper metal layer on the side closer to the upper layer is set to be lower than that on the side closer to the base layer. Ions of the metal forming the side metal layer Characterized in that it was larger than the trend.

Various kinds of metals forming the above "underlayer" and "upper layer" can be selected within the scope of the present invention. For example, as the metal forming the underlayer, relatively inexpensive Ni, Cu, Fe, or the like is used, and by making this layer thick, it is possible to further reduce the manufacturing cost of the wiring board. Is preferred and is preferable. Further, as the noble metal constituting the upper layer, Au, Pd, Pt, Rh, A
Other than g, Ru, etc., Os, Ir, etc. can be illustrated. The upper layer and the underlayer may each be composed of two or more metal layers.

Further, the kind of metal forming each metal layer forming the above "intermediate layer" can be variously selected within the scope of the present invention. However, it is necessary to arrange the “upper metal layer” and the “lower metal layer” having the above relationship.
For example, the upper metal layer is made of Ni (may be Cu, Fe, etc.), and the lower metal layer is made of Pd (Au, Pt, R).
Other noble metals such as h, Ag, Ru, Os, and Ir may be used. ) [Upper metal layer / lower metal layer; Ni
/ Pd, Ni / Au, Ni / Pt, Ni / Rh, Ni /
Ag, Ni / Ru, Ni / Os, Ni / Ir (in each combination example of these, instead of Ni, Cu, Fe
The same is true even if the above is used. )] Can be illustrated. Further, as a metal constituting each of the metal layers forming the above-mentioned base layer, upper layer and intermediate layer, a predetermined alloy [Pd and A
u alloy (hereinafter referred to as “Pd · Au”),
Pd.Ag, Au.Ag, etc.] can also be used.

The number of metal layers forming the intermediate layer can constitute at least one set of "upper metal layer and lower metal layer" having the above relationship (relationship of ionization tendency). As long as it does not matter. Further, when the intermediate layer is composed of three or more metal layers, other metal layers (the size of the ionization tendency is particularly important) other than the “upper metal layer and the lower metal layer” in the above relationship. A metal layer) ”may be additionally disposed. However, when arranging this "other metal layer" on the upper surface side of the upper metal layer, the ionization tendency of the metal forming the upper metal layer should be greater than the ionization tendency of the metal forming the upper metal layer. Is preferred. Further, when the "other metal layer" is arranged on the lower surface side of the lower metal layer, the ionization tendency of the metal forming the lower metal layer should be smaller than that of the metal forming the lower metal layer. It is preferable to achieve the object of the present invention more effectively. That is, when the number of metal layers is three or more, it is preferable that the metal forming the metal layer located closer to the upper layer has a greater ionization tendency.

Further, in the case where three or more metal layers are provided, even if the upper metal layer is arranged at a position in contact with the upper ground layer,
The “other metal layer” may be arranged between the upper ground layer and the upper ground layer. Also, regarding the lower metal layer, even if the lower metal layer is arranged at a position in contact with the underlayer, the above-mentioned “other metal layer” is formed between the lower metal layer and the underlayer.
May exist. Further, when four or more metal layers are provided, there may be two or more combinations of the “upper metal layer and lower metal layer” having the above relationship.

In the second aspect of the present invention, the metal forming the upper layer in the first aspect of the invention is Au, Pd, Pt, Rh, Ag.
Or Ru, the upper metal layer is Ni, the lower metal layer is Au, Pd, Pt, Rh, Ag or Ru, and the underlayer is Ni. In the present invention, the upper metal layer and the lower metal layer are made of noble metal having excellent corrosion resistance, and the upper metal layer and the base layer are made of relatively inexpensive Ni.

Further, among the combinations of the respective metals forming the respective layers of the upper layer and the lower metal layer (36 possible combinations in the second invention), a preferable combination is the upper layer /
Lower metal layer: Au / Au, Au / Pd, Au / Pt, A
There are 6 types of u / Rh and Au / Ag (however, the other 30 types also show sufficient anticorrosion performance). Furthermore, among these, those showing particularly good anticorrosion performance are
There are two types, Au / Pd and Au / Rh. In these two cases, particularly good performance is shown in that the lower metal layer is made of a metal that is less porous than the upper layer (hereinafter referred to as "non-porous") (in other words, the lower metal layer is It is more difficult to form pinholes than the upper layer, or even if pinholes are formed, the diameter is small and the number of holes is small.
It is because it is done.

The wiring board according to the third aspect of the present invention is the same as the wiring board according to the first aspect of the present invention, in which the plated portion is sandwiched by an underlayer and an overlayer similar to those of the first aspect of the invention. A multilayer structure including an intermediate layer formed of one or more metal layers, which is disposed in a portion, and the metal forming the upper layer is Au, Pd, Pt, Rh, Ag or Ru, and the intermediate layer is formed. Among these metal layers, the metal forming the uppermost metal layer arranged at the position closest to the upper layer is Au, Pd, Pt, Rh, Ag, or Ru.

In the present invention, at least two or more precious metal layers are arranged near the surface of the plated portion to improve corrosion resistance and appearance. Also in the present invention, it is particularly preferable that the uppermost metal layer is composed of a metal that is more non-porous than the upper layer. In the present invention as well, similar to the second invention, six preferable combinations can be exemplified (provided that the metal constituting the “lower metal layer” in the second invention is the present invention). It becomes the metal that constitutes the "top metal layer". Of these, Au /
In the combination of Au and the like, a portion close to the surface side of the plated portion is formed by two layers made of the same metal.

The thickness of each "layer" constituting the wiring board shown in the first to third inventions is not particularly limited, but as shown in the fourth invention, each metal layer constituting the upper layer and the intermediate layer. The thickness of the underlayer may be 0.05 to 0.15 μm, and the thickness of the underlayer may be 0.9 to 2.7 μm. In this case, it is suitable for a wiring board for an IC card (bank cash card or the like) having a relatively thick plated portion.

The wiring board manufacturing method of the fifth invention is the wiring board of the first invention, and the wiring board manufacturing method of the sixth invention is the wiring board of the third invention.
This is an example of a method of manufacturing by the "reel method". However, the manufacturing method of the wiring board shown in the first and third inventions is not limited to these. The "film-shaped wiring board substrate (including a long one)" of the first to fourth inventions, and the "long film-shaped wiring board substrate" shown in the fifth and sixth inventions. There is no particular limitation on the type, shape or the like. For example, glass epoxy, PET, polyimide, etc. can be illustrated.

[0020]

The wiring board according to the first aspect of the present invention comprises a film-shaped wiring board base material, a conductive pattern portion formed on the base material,
And a plated portion that covers the conductive pattern portion. Then, the plated portion was sandwiched by an underlayer arranged at a position in direct contact with the surface of the conductive pattern, an upper layer made of a noble metal, which constitutes the surface and the surface side portion of the plated portion, and these. And an intermediate layer formed of two or more metal layers, the multi-layer structure being provided. As a result, even when a thick plated portion (layer) is required, it is not necessary to form the entire plated portion with an expensive precious metal such as gold, and the manufacturing cost can be reduced and the precious metal can be reduced. Because the part of is thin,
The so-called "reel-to-reel method" facilitates the plating process and improves the production efficiency of the wiring board.

In at least one set of two adjacent metal layers among the metal layers forming the intermediate layer,
The upper metal layer is composed of a metal having a greater ionization tendency than the lower metal layer (that is, a metal that is easily corroded). As a result, water, moisture, etc. enter from the pinhole of the upper layer (mainly, the layer is a pinhole formed of a relatively porous precious metal and is relatively thin), and the upper side Even when the metal layer is corroded, it is possible to substantially prevent the corrosion from reaching the lower metal layer.

That is, in such a corrosive environment, the upper metal layer having a large ionization tendency (base) becomes the anode portion, and the lower metal layer having a small ionization tendency (noble) becomes the cathode portion. Therefore, even if dissolution (corrosion) progresses in the upper metal layer, it is difficult for dissolution (corrosion) progresses in the lower metal layer. Therefore, in the wiring board of the present invention, it is possible to effectively prevent the plated portion from being corroded so as to cause a trouble in use (for example, corrosion that extends to the underlying layer).

In the wiring board of the second aspect of the present invention, in the first aspect of the invention, the metal forming the upper layer and the lower metal layer in the first aspect of the invention is Au, Pd, Pt, Rh, Ag or Ru. Therefore, in this wiring board, two or more layers of noble metal with excellent corrosion resistance are arranged in the plated part (especially,
Since the noble metal is arranged in the intermediate layer), the above "corrosion preventive function due to the difference in ionization tendency between the upper metal layer and the lower metal layer" can be more reliably exhibited. Further, in the present invention, the underlayer and the upper metal layer are made of Ni. As described above, since there are two or more layers made of relatively inexpensive Ni, it is easy to adjust the thickness of the upper layer and the like by appropriately adjusting the thickness of the layers. As a result, it becomes easy to increase or decrease the amount of expensive precious metal constituting the above-mentioned formation.

When the lower metal layer is made of a metal that is more porous than the upper layer (for example, the upper layer is Au,
And the lower metal layer is composed of Pd. ), It is more difficult to form pinholes in the lower metal layer than in the upper layer, or even if they are, the hole diameter becomes smaller,
Fewer holes. Then, in such a case, water and the like that have entered through the pinholes of the upper ground layer can be substantially stopped at the lower metal layer (on the surface of the same metal layer).
As a result, the above "corrosion preventive function" can be exerted more reliably.

The wiring board of the third invention is the same as the wiring board of the first invention, and the plated portion is arranged in the same underlying layer and upper layer as in the first invention, and in a portion sandwiched therebetween. And an intermediate layer formed of one or more metal layers. Among the metal layers forming the upper ground layer and the intermediate layer, the metal forming the uppermost metal layer located closest to the upper ground layer is A
u, Pd, Pt, Rh, Ag or Ru. Therefore,
In the present invention, at least two or more precious metal layers having excellent corrosion resistance are arranged on the surface side of the plated portion.
It is possible to prevent corrosion that would hinder the use of the plated part.

Also in the present invention, the uppermost metal layer can be composed of a metal that is more non-porous than the upper layer. Even in such a case, water and the like that have entered through the pinholes of the upper ground layer can be almost stopped at the uppermost metal layer portion (on the surface of the same metal layer). Therefore,
The anticorrosion performance of the plated portion can be exhibited more effectively. Further, in the present invention, since the noble metal is arranged immediately below the upper layer, the pinholes in the upper layer are less noticeable. This is because when the wiring board is looked into from above (from above the upper layer), the surface of the uppermost metal layer is observed from the pinhole of the upper layer, and the pinhole becomes difficult to see. Therefore, the wiring board of the present invention,
It becomes excellent in decorativeness.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples. (1) Example 1 The wiring board K of this example is shown in FIG.
It shows a piece. ) Is a substrate for an IC card, and is a glass epoxy base material (wiring board base material, outer shape; 12 mm × 12 mm × 0.12 (thickness),
A conductive pattern 2 (21, 22, 23, etc.) formed of copper (a predetermined barrier layer may be provided on the surface of copper) and formed on the contact surface 11 of the base material portion 1, and the conductive pattern. The plating part 3 which covers 2 is provided.

A large part for mounting an electronic component 91 (shown by a chain double-dashed line in the figure) as shown in FIG. 1 from the bonding surface 12 side of the base material portion 1 near the center of the base material portion 1. The through hole 13 is provided, and eight small through holes 141, 1 for passing a predetermined bonding wire (shown by a chain line in the figure) 92 around the large through hole 13 are provided.
42 and the like are provided. The wiring board K is mounted on a base portion (indicated by a chain line in the figure) F of an IC card as shown in FIG. 1 with the contact surface 11 facing upward. .

In this embodiment, a long wiring board substrate (width: 120 mm, thickness: 0.1) as shown in FIG.
2 mm) L was plated using the plating device 8 as shown in FIG. 3 to produce the wiring board K. This long-sized wiring board substrate (hereinafter referred to as "long substrate")
L is made of glass epoxy and, as shown in FIG. 2, in the longitudinal direction, the above-mentioned base material portion (the base material portion where the portion surrounded by the broken line in the figure is one piece of the final product). 1) are continuously arranged, and these form six rows of base material portions (hereinafter referred to as “base material portion rows”) P _{1 to} P ₆ . In addition, adjacent base material portion rows P ₁ and P ₂ , P ₃ and P
₄ , P ₅ and P ₆ form a group of three base material section rows (hereinafter referred to as “base material section row group”).

In each portion of the long base material L corresponding to each base material portion 1, each through hole 13, 141, 142, etc. as shown in FIG. 1 (not shown in FIG. 2) and The conductive pattern 2 has already been formed. In addition, around these conductive patterns 2, a plating lead (made of copper, not shown) for electrically conducting the cathode side of the predetermined power feeding portion (device) and the conductive patterns 2 is provided. It is provided.

Outside side sprocket holes S ₁ and S ₂ are provided on the side surface along the longitudinal direction of the long base material L for facilitating the transportation of the base material L in the plating process and the like. ing. Further, on both sides of the base member row group, along the longitudinal direction of the long base material L, inside sprocket holes S ₃₁ ,
S ₃₂ , S ₄₁ , S ₄₂ , S ₅₁ , and S ₅₂ are continuously arranged.
The inner sprocket holes S ₃₁ , S _32, etc. are formed by dividing the long base material L into the base material row groups (slit processing).
Post-process to be performed after (for example, electronic component mounting process)
This is for facilitating the transportation of the divided group of base material portion groups when applying. The number of the base portion rows, the base portion row groups arranged on the long base material L, the width, the thickness, the material of the long base material L, the arrangement of the plating leads, etc. are limited to those described above. Not a thing.

On the other hand, as shown in FIG. 3, the plating device 8 is provided with a plating tank 81, a plating solution 82 accommodated in the plating tank 81, and a position above the plating solution 82 and facing each other. Rolled in for carrying in (also performs power supply operation) 8
31 and the roll 832 for carrying out, and the 1st auxiliary | assistant roll 841 and the 2nd which were arrange | positioned at the position which mutually opposes in the same liquid 82.
Auxiliary roll 842 and P placed in the plating solution 82
t plates 851 to 853. Then, in the present example, four types of such plating devices (first to fourth plating devices) were used and plating was performed as follows.

First, in the first plating apparatus, while the contact surface 11 faces the Pt plate 851 side of the long base material L wound on a predetermined supply roll, the loading roll 831 is moved. Through the plating solution 82. The plating solution 82 is a bright plating bath, and a current of 2.2 A / dm ² is applied to the substrate L passing therethrough.

Then, the long base material L is attached to the first auxiliary roll 84.
While passing over the first and second auxiliary rolls 842 in this order, the plating solution 82 is conveyed (transfer speed: 1.2 m / mi).
n), Ni plating (thickness: 0.
(About 1 to 0.3), and then the carry-out roll 83
It is carried out from the plating solution 82 through the No. 2. Further, this plating operation is repeated until the thickness of the Ni plating becomes about 1.8 μm (using the first plating apparatus as it is or using another plating apparatus similar to the first plating apparatus), The underlayer 31 shown in FIG. 4 was formed. still,
The formation of the underlayer 31 is divided into a plurality of times as described above because the underlayer 31 is relatively thick. Therefore, the underlayer 31 is relatively thin (thickness: 0.1 to 0.3).
The same layer 3 by one plating operation.
1 can also be formed.

Then, the long base material L on which the underlayer 31 is formed is subjected to Pd plating in the second plating apparatus in the same manner as the above Ni plating. However, in this case, since the target lower metal layer is thin, the long base material L is only subjected to the plating operation once (in this respect, the upper side described later). The same applies to the formation of the metal layer and the upper layer.) Further, the plating solution 82 used in this Pd plating is
K-Pure Palladium [trade name, manufactured by Kojima Chemical Co., Ltd.]. The current applied to the passing substrate L is 1 A /
Although it is dm ² , the transfer speed of the base material L is the same as that in the case of Ni plating. The layer formed by this plating operation is the lower metal layer (thickness: about 0.1 μm) 321 that covers the underlayer 31.

Next, the long base material L is plated with Ni using a third plating apparatus. At this time, the plating solution 82, the electric current applied to the passing base material L, the transfer speed of the base material, and the like are the same as in the case of the first plating apparatus. The layer formed by this operation is the lower metal layer 3 described above.
Upper metal layer 21 (thickness; about 0.1 μm) 32
It is 1. Further, the long base material L is subjected to Au plating by using the fourth plating apparatus, and the wiring board K is continuously manufactured. The plating liquid 82 at this time is Temperex 401 [trade name, manufactured by EEJA Corporation]. Also,
The current applied to the excess base material L is 0.2 A / dm ² , but the transfer speed of the base material is the same as in the case of the first plating apparatus. And the layer formed by this operation is
It is an upper layer (thickness; about 0.1 μm) 33 that constitutes the surface and the surface side portion of the plated portion 3.

In the wiring board K manufactured as described above, the upper metal (Ni) layer 322 is lower metal (Pd).
Since the upper metal (Ni) layer 322 serves as an anode portion in a corrosive environment, the lower metal (P) is used because it is made of a (base) metal having a greater ionization tendency than the layer 321.
d) Layer 321 acts as the cathode portion. Therefore, there is a pinhole h as shown in FIG. 4 in the upper ground layer 33, water or the like enters the upper metal layer 322 from there, and as shown in FIG. 5, corrosion of the same metal (Ni) layer 322 ( Even if (dissolution) proceeds, corrosion (dissolution) does not easily proceed in the lower metal (Pd) layer 321. As a result, it is possible to accurately prevent the corrosion of the plated portion, which may cause a trouble in use.

Further, even if the upper layer 33 (also the lower metal layer 321) made of an expensive precious metal is thin as described above, a firm anticorrosion property can be maintained, so that the manufacturing cost of the wiring substrate K can be reduced. It is possible to maintain high performance and quality for a long period of time while improving manufacturing efficiency by low cost, so-called "reel to reel system". Further, in this embodiment, since the lower metal layer 321 is formed of Pd that is less likely to form pinholes than Au that forms the upper layer 33, water or the like entering through the pinhole h of the upper layer 33 is Even when reaching the upper surface side of the layer 321, it is difficult to enter the underlayer beyond the same layer. Therefore, the above-mentioned "corrosion preventive function due to the difference in ionization tendency between the upper metal layer 322 and the lower metal layer 321" can be exhibited more reliably.

Further, in this embodiment, the upper layer 33 is formed as a porous layer made of Au, and the lower metal layer 32 is formed.
In particular, since 1 is configured as a non-porous layer made of Pd, it exhibits a particularly good anticorrosion function. Even if the combination of the metals forming the upper layer 33 and the lower metal layer 321 is replaced with the upper layer / lower metal layer; Au / Rh, a particularly good anticorrosion function similar to that of the present embodiment can be obtained. , Au / Au, Au
Even with / Pt or Au / Ag, a good anticorrosion function can be obtained. Further, even if one of the other 30 combinations shown in the second aspect of the present invention is selected, sufficient anticorrosion performance can be obtained. In addition, the base layer 31 and the upper metal layer 32
Similar results can be obtained even if both or one of the two is made of Cu, Fe, or the like. Furthermore, the metal constituting the upper ground layer, the lower metal layer, etc. is "Pd-Au",
It is also possible to use an alloy such as "Pd / Ag" or "Au / Ag".

As a modification of this embodiment, a wiring board having a plated portion 3a as shown in FIG. 6 can be exemplified. In this wiring board, the intermediate layer 32a is composed of three metal layers 321a to 323a. In this case, even if the lower metal layer is 321a and the upper metal layer is 322a, the lower metal layer is 322a,
In addition, the upper metal layer may be 323a. Also, 3
Each metal layer can be made of a metal having a large ionization tendency as it goes upward toward 21a to 323a. Further, the number of metal layers constituting the intermediate layer may be four or more, and in this case, the combination of the lower metal layer and the upper metal layer having the above-mentioned relation of magnitude of ionization tendency is set to two.
You may arrange more than one group.

(2) Example 2 The wiring board of this example has a plated portion 3b as shown in FIG. This wiring board has a configuration in which the upper metal layer 322 is removed from the wiring board K of the first embodiment. Further, this wiring board was manufactured by the same method as in Example 1 except that the third plating apparatus was not used. In this embodiment, the upper layer 33b is Au,
The metal layer (uppermost metal layer) 321b in contact with the layer 33b is made of Pd. As described above, since two layers of noble metal having excellent corrosion resistance are arranged on the surface side of the plated portion 3b, it is possible to prevent the corrosion of the plated portion 3b which may cause a trouble in use. be able to.

Also in this embodiment, since the uppermost metal layer 321b is non-porous, water or the like that has entered through the pinhole of the upper layer 33b can be firmly stopped by this metal layer 321b. Therefore, this corrosion preventing function can be surely exhibited. Further, since the metal layer composed of Pd is arranged directly below the upper layer,
The pinholes in the upper ground layer are less noticeable, and the appearance and decoration are excellent.

Also in this embodiment, the above-mentioned first embodiment is used.
Similarly to the above, the upper layer 33b and the metal layer (uppermost metal layer) 3
Even if the combination of 21b is changed, good results can be obtained. Further, another metal layer forming the intermediate layer may be arranged between the metal layer (uppermost metal layer) 321b and the base layer 31b.

The present invention is not limited to the specific examples described above, and various modifications may be made within the scope of the present invention according to the purpose and application. That is,
Although the long wiring board L is used in this embodiment, the present invention can be applied to other wiring boards (for example, a plate-shaped base material having a small outer shape). Further, in each of the embodiments, the wiring board is manufactured by the so-called "reel to reel method", but the manufacturing method is not limited to this.

[0045]

The wiring board of the present invention has a relatively thick plated portion, can maintain high performance and quality for a long period of time, and can be efficiently manufactured at low cost. Further, according to the method for manufacturing a wiring board of the present invention,
A so-called "reel-to-reel system" plating method can be used to efficiently and inexpensively manufacture a high-performance, high-quality wiring board.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a wiring board according to Examples 1 and 2 and a conventional example.

FIG. 2 is a plan view of a long-sized substrate used for manufacturing wiring boards according to Examples 1 and 2 and a conventional example.

FIG. 3 is a vertical sectional view showing an outline of a plating apparatus used in Examples 1 and 2 and a conventional example.

FIG. 4 is a vertical cross-sectional view showing the configuration of a plated portion of the wiring board of Example 1.

FIG. 5 is a vertical cross-sectional view for explaining a corroded state (corrosion prevention state) of a plated portion of the wiring board of Example 1.

FIG. 6 is a vertical cross-sectional view showing a configuration of a plated portion of a wiring board according to a modified example of Example 1.

FIG. 7 is a vertical cross-sectional view showing the configuration of a plated portion of a wiring board of Example 2.

FIG. 8 is a vertical cross-sectional view showing a configuration of a plated portion of a conventional wiring board.

FIG. 9 is a vertical cross-sectional view for explaining a corroded state of a plated portion of a conventional wiring board.

[Explanation of symbols]

K: wiring board, 1; base material portion (wiring board base material), 2 (2
1, 22, 23); conductive pattern, 3; plated part, 3
1; Base layer, 32; Intermediate layer, 321; Lower metal layer, 32
2; upper metal layer, 32; upper ground layer, 321a to 323a;
Metal layer, 321b; metal layer (uppermost metal layer), L; elongated wiring base material, P _{1 to} P _6, base material row, 8; plating device.

Claims (6)

[Claims] 1. A film-shaped printed wiring board base material, a conductive pattern portion formed on at least one of the front and back surfaces of the printed wiring board base material, and a plated portion that covers the conductive pattern portion. In a printed wiring board provided with, the plated portion, an underlayer disposed at a position in direct contact with the surface of the conductive pattern, an upper layer made of a noble metal, which constitutes the surface and the surface side portion of the plated portion, At least one of the metal layers forming the intermediate layer has a multi-layer structure including an intermediate layer formed of two or more metal layers and arranged in a portion sandwiched between the underlayer and the upper layer. Of the two adjacent metal layers of the set, the ionization tendency of the metal forming the upper metal layer on the side closer to the upper ground layer, and the ionization tendency of the metal forming the lower metal layer on the side closer to the base layer Greater than Printed circuit board, characterized in that there was a comb. 2. The metal forming the upper layer is Au or P
d, Pt, Rh, Ag or Ru, the upper metal layer is N
The printed wiring board according to claim 1, wherein i, the lower metal layer is Au, Pd, Pt, Rh, Ag, or Ru, and the underlayer is Ni. 3. A film-shaped printed wiring board base material, a conductive pattern portion formed on at least one of the front and back surfaces of the printed wiring board base material, and a plated portion covering the conductive pattern portion. In a printed wiring board provided with, the plated portion, an underlayer disposed at a position in direct contact with the surface of the conductive pattern, an upper layer made of a noble metal, which constitutes the surface and the surface side portion of the plated portion, A multilayer structure including an underlayer and an intermediate layer formed of one or more metal layers arranged in a portion sandwiched between the underlayer and the upper layer, wherein the metal forming the upper layer is Au, Pd, Pt, or Rh. ,
Among the metal layers forming Ag or Ru and the intermediate layer, the metal forming the uppermost metal layer arranged at the position closest to the upper layer is Au, Pd, Pt, Rh, Ag or Ru. A printed wiring board characterized by the above. 4. The thickness of the upper layer and the thickness of each metal layer forming the intermediate layer are each 0.05 to 0.15.
The printed wiring board according to any one of claims 1 to 3, wherein the underlayer has a thickness of 0.9 to 2.7 µm. 5. A printed wiring board base material is formed by a reel-to-reel method after forming conductive patterns at predetermined positions on at least one of the front and back surfaces of a long film-shaped printed wiring board base material. In a method of manufacturing a printed wiring board by continuously transporting in a predetermined plating tank and performing electroplating for each conductive pattern portion to form a predetermined plated portion, An underlayer directly contacting the surface, an intermediate layer formed by two or more metal layers disposed on the underlayer, and an intermediate layer formed on the intermediate layer and having the surface and the surface side portion of the plated portion Of the two adjacent metal layers of at least one set among the metal layers forming the intermediate layer, which are formed on the side close to the upper ground layer. The upper metal layer The ionization tendency of the metal to be formed, a manufacturing method of a printed wiring board, characterized in that is larger than the ionization tendency of the metal constituting the lower side metal layer on the side closer to the underlying layer. 6. A printed wiring board base material is formed by a reel-to-reel method after forming conductive patterns at predetermined positions on at least one of the front and back surfaces of a long film-shaped printed wiring board base material. In a method of manufacturing a printed wiring board by continuously transporting in a predetermined plating tank and performing electroplating for each conductive pattern portion to form a predetermined plated portion, An underlayer that is in direct contact with the surface, an intermediate layer formed by one or more metal layers disposed on the underlayer, and disposed on the intermediate layer to form the surface and the surface-side portion of the plated portion. Then, the upper layer made of a noble metal is formed in this order as a multilayer structure, and the metals forming the upper layer are Au, Pd, Pt, Rh,
Among the metal layers forming Ag or Ru and the intermediate layer, the metal forming the uppermost metal layer arranged at the position closest to the upper layer is Au, Pd, Pt, Rh, Ag or Ru. A method of manufacturing a printed wiring board, comprising: