JP2000277889A - Transfer medium, method for manufacturing the transfer medium, and method for manufacturing a wiring pattern using the transfer medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer medium in which a conductive layer is provided on the whole surface of a base material or a desired pattern, and further, conductive wiring of a desired pattern is provided on the surface of the conductive layer. By using a transfer medium made of a material in which at least the conductive wiring and the base material can be selectively removed by a different etchant, the yield can be improved without causing disconnection or deformation of a fine wiring pattern. Manufactures fine circuit boards. SOLUTION: A Zn-based conductive layer 103 is formed on the surface of an Al base material 101 by electroplating, and a desired pattern is formed on the surface of the conductive layer with a photosensitive resin 104. After the pattern is formed, a Cu conductive wiring 105 is formed in a region where the conductive surface is exposed, and the photosensitive resin is removed with an alkaline aqueous solution to manufacture a transfer medium. After embedding the conductive wiring of the transfer medium in the insulating substrate, the conductive layer and the base material are removed with hydrochloric acid to obtain a desired wiring pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer medium having a fine wiring pattern for manufacturing a wiring board on which various electronic components can be mounted and electrically connected to each other to form an electronic circuit. The present invention relates to a method for manufacturing the transfer medium and a method for manufacturing a wiring pattern using the transfer medium.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic devices, there has been a strong demand that circuit boards on which semiconductor chips such as LSIs can be mounted at a low cost can be used not only in industrial applications but also in the field of consumer devices. I have. In such a circuit board, it is important that a finer wiring pitch can be easily produced at a high yield in order to achieve the purpose of miniaturization by increasing the mounting density.

Conventionally, in a circuit board, a method has been adopted in which a copper foil is stuck on a so-called glass epoxy substrate in which a glass woven fabric is impregnated with an epoxy resin, and a pattern is formed by photoetching the copper foil. In such a method, the surface of the copper foil is roughened in order to maintain the adhesion between the copper foil and the glass epoxy substrate. Therefore, the copper foil becomes thick and it is difficult to form a fine pattern.

In order to solve this problem, for example, a fine pattern is formed on another substrate in advance by electroplating and the like, and then pressed and transferred to an insulating substrate, and thereafter, only the substrate is mechanically peeled off. A method has also been proposed (Japanese Patent Application Laid-Open No. 6-318873).

[0005]

However, according to the method disclosed in Japanese Patent Application Laid-Open No. 6-318873, the conductive pattern is separated depending on the peel strength between the conductive pattern and the substrate. That is, in this method, the weaker one is peeled off due to a difference in mechanical adhesion strength, but in this case, it is considerably difficult to control the adhesion strength between the substrate side and the insulating base material side of the conductive pattern. In particular, as the pattern becomes finer, the contact area between the conductive pattern and the insulating base material becomes smaller, the adhesion strength becomes weaker, and it becomes difficult to peel off only the substrate. Therefore, the yield is reduced due to deformation or disconnection of the conductive pattern.

[0006]

According to the present invention, at least a transfer medium in which a conductive layer is provided on the entire surface of a substrate or a desired pattern, and a conductive wiring of a desired pattern is provided on the surface of the conductive layer. The conductive wiring and the base material are made of a material that can be selectively removed by a different etchant. After the conductive wiring of the transfer medium is embedded in the insulating substrate, the base material is removed. Therefore, in the present invention, the base material and the conductive wiring are separated by such a transfer method, and the base material and the conductive wiring are not mechanically separated from each other as in the related art. As a result, the weaker one does not peel off, and a fine wiring pattern with weak adhesion strength can be easily formed. Furthermore, in the present invention, a conductive layer for facilitating the formation of conductive wiring on the base material, in particular, a conductive layer for facilitating the growth and formation by plating, and the conductive wiring are made of a different material of the etching solution, so that the transfer pressing is performed. The selectivity for leaving only the conductive wiring by the etching in the above can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first transfer medium of the present invention is a transfer medium in which a conductive layer is provided on the surface of a base material, and conductive wires of a desired pattern are further provided on the surface of the conductive layer, The conductive wiring, the base material, and the conductive layer are made of a material that can be selectively removed by different etchants. According to this transfer medium, only the conductive wiring of the desired pattern can be left after the transfer. Further, only the conductive wiring can be easily left selectively after the transfer by the chemical etching.

According to a first method of manufacturing a transfer medium of the present invention, a step of forming a conductive layer on the surface of a base material, a step of forming a pattern in a desired region with an insulating material on the surface of the conductive layer,
Forming a conductive wiring of a material that can be selectively removed from the base material and the conductive layer with a different etchant in a region where the surface of the conductive layer is exposed after the pattern is formed. With this method, the first transfer medium can be manufactured.

In a second transfer medium of the present invention, a conductive layer having a desired pattern and a conductive wiring are sequentially provided on the surface of a base material,
At least the conductive wiring and the substrate are made of a material that can be selectively removed by different etching solutions. According to this transfer medium, it is possible to eliminate the need for selective removal of the conductive layer and the conductive wiring by forming the conductive layer and the conductive wiring in a desired pattern. Further, the conductive wiring and the conductive layer can be easily left selectively after the transfer by the chemical etching.

In the second transfer medium, it is preferable that the conductive layer and the conductive wiring of the desired pattern are made of a material that can be selectively removed by different etching solutions. Accordingly, even in the second transfer medium, only the conductive wiring of a desired pattern can be selectively left after the transfer.

According to a second method of manufacturing a transfer medium of the present invention, a step of forming a desired pattern on a surface of a substrate with an insulating material and a step of forming a conductive layer in a region where the surface of the substrate is exposed after pattern formation. And a step of forming a conductive wiring which can be selectively removed from the base material with a different etching solution on the surface of the conductive layer. By this method, a second transfer medium can be manufactured.

In the first or second method for producing a transfer medium according to the present invention, it is preferable that the conductive layer and the conductive wiring are formed by plating. Thus, the first and second transfer media can be easily manufactured. Further, it is preferable that the base material is formed of a conductive material, and the plating of the conductive layer and the conductive wiring is electroplating. Thereby, the conductive wiring of the desired pattern on the transfer medium can be formed more selectively.

In the first method of manufacturing a transfer medium according to the present invention, it is preferable that the conductive layer provided on the surface of the substrate is formed by sputtering or vapor deposition. Thus, the first transfer medium can be manufactured without restriction on material selection such as plating in forming the conductive layer.

In the first or second method for producing a transfer medium according to the present invention, the conductive layer plated on the surface of the base material is removed at least once and the conductive layer is formed again, and then the conductive wiring is formed. Is preferred. Thereby, when manufacturing the first and second transfer media, it is possible to obtain a conductive layer having better adhesion and being more chemically stable.

According to a first method of manufacturing a wiring pattern of the present invention, a step of embedding a conductive wiring of a first or second transfer medium in an insulating substrate and removing a base material and a conductive layer of the transfer medium are provided. And a step of performing With this method, it is possible to manufacture a wiring pattern using the various transfer media.

According to a second method of manufacturing a wiring pattern of the present invention, a step of embedding a conductive layer and a conductive wiring of a second transfer medium in an insulating substrate, and a step of removing a base material of the transfer medium are provided. It is characterized by including. According to this method, a wiring pattern using the second transfer medium can be manufactured.

In the first or second method of manufacturing a wiring pattern according to the present invention, it is preferable that a through hole is provided in the insulating substrate, and the through hole is in an electrically conductive state.
Thereby, the wiring pattern by the transfer medium is formed on both surfaces of the insulating substrate, and the wiring patterns on both surfaces are electrically connected at desired portions. Further, it is preferable that the through hole is in an electrically conductive state by being filled with a conductive paste. Thereby, the surface of the wiring pattern can be flattened even in the through hole of the wiring pattern by the transfer medium.

Hereinafter, embodiments of the present invention will be described with reference to the drawings with reference to specific examples of a wiring board.

(Embodiment 1) As shown in FIG. 1A, as a base material 101, for example, Al is used as a conductive material in order to facilitate electroplating in a later step. This Al may not be of high purity but may be a mixture of impurities. To improve mechanical strength such as rigidity and spring property, it is preferable to use impurities such as Fe, Mn, and Si in the material. It is desirable to mix in the range of 0.001 to 0.1% by weight. Here, A which is the material of the substrate 101
1 is a material that does not etch Cu, which is a material of the conductive wiring 105 of a desired pattern, with an Al etchant described in a later step. As described above, the material of the base material 101 is a material having appropriate mechanical strength and conductivity, and the conductive wiring 105
Is a material which is not etched, or
Any material may be used, as long as the etching rate of the conductive wiring 105 with the etching solution is as low as 50% or less, for example. This is because, after transferring the transfer medium created in the present embodiment to the insulating base material, when the base material 101 and the conductive layer 102 formed in the next step are removed by etching, the conductive wiring 105 is formed by over-etching. Is also important to prevent the etching of Cu and the change in pattern dimensions due to the thinning of fine conductive wiring and the formation of grooves between itself and the insulating layer.

Next, as shown in FIG. 1B, a conductive layer 102 is formed by electroplating. This conductive layer 1
02 uses, for example, a Zn-based material. Here, the conductive layer 102 is etched by the etchant of the base material 101, or even if the etchant is different, the etching rate for the conductive wiring is as low as that of the base material 101, It is necessary that the material is not used, and a Zn-based material is desirable because it is the same etchant as the base material 101.

Thereafter, as shown in FIG. 1C, the conductive layer 102 is removed with a nitric acid-based solution.
As shown in (D), the conductive layer 103 is formed by plating again. This is because the conductive layer 102 formed first has low density and low adhesion to the base material 101, and is attacked by an alkaline solution as a developing or removing solution of the photosensitive resin in a later step. This is because this can be prevented by forming again.

Further, Zn in the conductive layer 103
As a material of the system, Zn, Cu, Ni or the like is used in the material.
By mixing in the range of weight%, the aforementioned adhesion and chemical resistance are improved, and the fine conductive wiring 1
Particularly, it is easy to form the plating of Cu as 05. still,
By using vapor deposition or sputtering to form the conductive layer 103, not only good adhesion but also a layer in which a high density and a plurality of materials are mixed with high accuracy can be obtained.

Next, as shown in FIG. 1E, a pattern of the insulating material 104 can be formed by applying a photosensitive resin as the insulating material 104, and exposing and developing using a mask. The conductive layer 103 can be exposed in the region. As the photosensitive resin, for example, THB52
3 (registered trademark, manufactured by JSR Corporation). At this time, if a positive pattern that can easily form a fine pattern is used for the photosensitive resin, an alkaline solution such as an aqueous solution of about 1% by weight of sodium hydroxide is used for development. In this case, if the density of the exposed conductive layer 103 is low, the conductive layer 103 is peeled off as described above, because the aluminum of the base material 101 is attacked.

Next, as shown in FIG. 1F, a conductive wiring 105 is selectively formed only on the surface where the conductive layer 103 is exposed by electroplating. For example, Cu is used as the conductive wiring. At this time, since the base material 101 and the conductive layer 103 are conductive materials, electroplating can be easily adopted. That is, the fact that electroplating rather than electroless plating can be employed ensures that even fine pattern portions can be plated.

Thereafter, as shown in FIG. 1 (G), the transfer medium is manufactured by removing the photosensitive resin with an alkaline solution such as an aqueous solution of about 3% by weight of sodium hydroxide. In the removal of the photosensitive resin as well, the alkaline solution invades the Al of the base material 101, so that Z
There is a possibility that the n-type conductive layer 103 is peeled off and the conductive wiring 105 having a fine pattern made of Cu is also peeled off. However, this can be prevented by reforming the conductive layer 103. Here, by removing the photosensitive resin, the conductive wiring 105 made of Cu of the transfer medium becomes convex, and exhibits an effect of improving the compressive force to the conductive paste when the transfer medium is transferred by pressing. . However,
Even if the insulating material 104 is a material such as an epoxy resin or a photosensitive resin formed by printing, the material does not need to be particularly removed as long as the material can withstand the adhesive force after pressing the transfer medium and various reliability.

(Embodiment 2) As shown in FIG. 2 (H), for example, Al is used as a conductive material for a substrate 201 in order to easily enable electroplating in a later step. As described in the first embodiment, this Al may be not only high-purity but also one in which impurities are mixed. In order to improve mechanical strength such as rigidity and spring property, it is preferable to use Al. Impurities such as Fe, Mn, and Si are contained in the material.
It is desirable to mix in the range of 001 to 0.1% by weight.
Here, the reason why Al is used as the material of the base material 201 is the same as that described in the first embodiment, that is, the thinning of the conductive wiring 205 and the groove due to over-etching of the base material 201 described in a later step. This is for preventing the formation or the like.

Next, as shown in FIG.
1 is coated with a photosensitive resin as an insulating material 202, and is exposed and developed using a mask, whereby a pattern of the insulating material 202 can be formed.
01 can be exposed. For example, THB523 is used as the photosensitive resin.

Next, as shown in FIG. 2J, a conductive layer 203 is formed by electroplating. This conductive layer 1
As 02, for example, a Zn-based material is used.

Thereafter, as shown in FIG. 2K, the conductive layer 203 is removed with a nitric acid-based solution.
As shown in (L), the conductive layer 204 is formed by plating again. Thus, the conductive layer 204 which is dense and has good adhesion can be obtained as in the first embodiment. Note that, in Embodiment 2, unlike Embodiment 1, when the conductive layer 204 is formed by evaporation or sputtering, the conductive layer 204 is also formed on the surface of the insulating material 202, and the selectivity is lost. Cannot be hired. In addition, since the conductive layer 204 is formed in the same pattern as the conductive wiring 205, it is not necessary to particularly remove the conductive layer by etching, and a material which is not at all affected by the etchant of the base material 201 may be used. Therefore, in the present embodiment, the selectivity of the material of the conductive layer 204 is wide.

Further, as shown in FIG. 2M, a conductive wiring 205 is formed on the surface of the conductive layer 204 by, for example, electroplating Cu. Thereafter, as shown in FIG. 2N, a transfer medium is manufactured by removing the insulating material 202 made of a photosensitive resin with an alkaline solution such as a 5% by weight aqueous solution of sodium hydroxide. Also in this case, similarly to the first embodiment, insulating material 202
Need not be removed.

(Embodiment 3) In this embodiment, a case where the transfer medium manufactured in Embodiment 1 is used as a transfer medium will be described.

As shown in FIG. 3 (O), an adhesive layer 302 is provided on both sides of an insulating substrate 301 made of a polyimide film.
And a through hole 303 is formed with a laser or a drill. The insulating substrate 301 may be an aramid prepreg, a glass epoxy substrate, or the like.

Next, as shown in FIG.
03 is filled with a conductive paste 304 by printing or press-fitting. As the conductive paste 304, for example, a paste obtained by kneading a metal such as Cu, Ag, or Au with a resin such as an epoxy resin or an organic solvent is used. This conductive paste 304 is for electrically connecting both surfaces of the insulating substrate 301. Therefore, the conductive paste 304
Is filled to eliminate the unevenness in the through hole 303 and flatten the surface. However, Cu or the like may be applied around the through hole 303 by electroless plating or the like.

Next, as shown in FIG. 3 (Q), a substrate 305 made of Al and a Zn-based conductive material are placed on an insulating substrate 301 of a polyimide film having an adhesive layer 302 adhered to both front and back surfaces. Transfer medium constituted by layer 306 and conductive wiring 307 made of Cu, and base material 30 made of Al
8, a Zn-based conductive layer 309, and a conductive wiring 310 made of Cu, the conductive wiring 307 and the conductive wiring 310 are opposed to the front and back adhesive layers 302, respectively. Press bonding is performed in the state of being performed. still,
By performing the press bonding at an appropriate temperature of, for example, about 200 ° C., the bonding effect is further improved.

As shown in FIG. 3 (R) by pressing,
Cu conductive wires 307 and 310 are embedded in the adhesive layer 302, and the conductive paste 304 in the through-hole is compressed by the conductive wires 307 and 310 on both the front and back sides, so that the connection is more reliable and good. Become.

Thereafter, as shown in FIG. 3 (S), the substrates 305 and 308 of the transfer medium and the conductive layers 306 and 309
Is removed. At this time, the material of the base materials 305 and 308 is A
For example, the conductive layers 306 and 309 can be easily removed with hydrochloric acid because the conductive layers 306 and 309 are also Zn-based. However, since the conductive wirings 307 and 310 are made of Cu, they are not affected by hydrochloric acid. Therefore, the necessary conductive wirings 307 and 310 can be selectively left after the transfer medium is pressed to remove the bases 305 and 308 and the conductive layers 306 and 309 at the same time, but this is important.

For example, when the conductive layers 306 and 309 are made of the same material as the conductive wiring or the same etchant or a layer containing the same,
That is, after a plating layer such as flash copper is formed on the surface of the Zn-based conductive layer to facilitate fine pattern plating of Cu, the conductive wirings 307 and 3 having a desired pattern are formed.
In the case where 10 is formed, the following problem occurs. That is, when the conductive layers 306 and 309 are removed by etching, the surfaces of the conductive wirings 307 and 310 are also etched by over-etching and the like, so that the thickness is reduced and the electrical resistance of the wirings is increased.
310 is etched to form a gap between the conductive wirings 307 and 310 and the adhesive layer 302, thereby impairing not only wiring resistance but also adhesion, and the conductive wiring 30
7, 310 may be peeled off.

[0038]

By using the transfer medium of the present invention, it is possible to easily produce a fine circuit board with a good yield without causing a break or deformation of a fine wiring pattern.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a process for manufacturing a transfer medium according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view illustrating a process for manufacturing a transfer medium according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view showing a step of manufacturing a wiring pattern according to a third embodiment of the present invention.

[Explanation of symbols]

101, 201, 305, 308 Base material 102, 103, 203, 204, 306, 309 Conductive layer 104, 202 Insulating material 105, 205, 307, 310 Conductive wiring 301 Insulating substrate 302 Adhesive layer 303 Through hole 304 conductive paste

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Nakamura 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Hideki Higashiya 1006 Odaka Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial F Terms (reference) 5E343 AA07 BB22 BB24 DD23 DD25 DD32 DD43 DD56 DD64 DD76 GG08 GG11

Claims (13)

[Claims] 1. A transfer medium in which a conductive layer is provided on a surface of a base material, and a conductive pattern having a desired pattern is provided on the surface of the conductive layer. A transfer medium in which a conductive layer is made of a material that can be selectively removed by different etchants. 2. A step of forming a conductive layer on a surface of a substrate,
A step of forming a pattern in a desired region with an insulating material on the surface of the conductive layer, and selectively removing the base material and the conductive layer by a different etching solution in a region where the conductive layer surface is exposed after pattern formation. Forming a conductive wiring of a possible material. 3. A conductive layer having a desired pattern and a conductive wiring are sequentially provided on a surface of a base material, and at least the conductive wiring and the base material are made of a material that can be selectively removed by different etchants. The transfer medium that is composed. 4. The transfer medium according to claim 3, wherein the conductive layer and the conductive wiring of the desired pattern are made of a material that can be selectively removed by different etching solutions. 5. A step of forming a desired pattern on a surface of a base material using an insulating material, a step of forming a conductive layer in a region where the surface of the base material is exposed after pattern formation, and a step of etching differently on the surface of the conductive layer. Forming a conductive wiring that can be selectively removed from the base material using a liquid. 6. The method according to claim 2, wherein the conductive layer and the conductive wiring are formed by plating. 7. The method for manufacturing a transfer medium according to claim 6, wherein the base material is formed of a conductive material, and the plating between the conductive layer and the conductive wiring is electroplating. 8. The method according to claim 2, wherein the conductive layer provided on the surface of the substrate is formed by sputtering or vapor deposition. 9. The conductive wiring according to claim 2, wherein the conductive layer formed on the surface of the base material is removed at least once and the conductive layer is formed again, and then the conductive wiring is formed. The method for producing a transfer medium according to claim 1. 10. The step of embedding the conductive wiring of the transfer medium according to claim 1, in the insulating substrate, and the step of removing the base material and the conductive layer of the transfer medium. And a method for manufacturing a wiring pattern. 11. A method comprising embedding the conductive layer and the conductive wiring of the transfer medium according to claim 3 in an insulating substrate, and removing the base material of the transfer medium. Method of manufacturing a wiring pattern. 12. The method according to claim 10, wherein a through-hole is provided in the insulating substrate, and the through-hole is in an electrically conductive state. 13. The method for manufacturing a wiring pattern according to claim 12, wherein the through holes are in an electrically conductive state by being filled with a conductive paste.