JPH06112628A - Manufacture of circuit board having wiring pattern - Google Patents

Abstract

PURPOSE:To form fine wiring patterns including land parts with narrow pitches and, further, form proper and highly accurate solder films for soldering of a surface mount component on the land parts of the wiring patterns. CONSTITUTION:A foundation film 2 made of active metal material and a conducting film 3 are built up on the surface of a board 1 by sputtering or vacuum deposition. A resist film 4 is applied to the conducting film 3 and exposed and developed to form through-holes having required patterns. Conducting layers 6 and metal plating films 7 such as solder films are formed in the through-holes 5. Then the resist film 4 is removed and the surplus foundation film 2 and conducting film 3 are removed from the surface of the board 1 by etching with the metal plating films 7 such as the solder films as metal masks. The metal plating films which are used as the metal masks are totally removed or the parts of the solder films 7 are left on the land parts and the other parts are removed from the surfaces of the wiring patterns 3 and 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a circuit board having a fine wiring pattern, which is suitable for narrowing the pitch and increasing the pin count of surface mount components.

[0002]

2. Description of the Related Art Generally, in order to form a wiring pattern on a plate surface of a circuit board, a screen printing method is applied by printing a paste-like conductive material using a mesh screen or a metal screen. However, in this screen printing method, factors such as the characteristics of the conductive material, the material of the screen, the thickness, the accuracy of the opening, the warp and twist of the printed substrate, the accuracy of the printing machine, the speed of printing, the printing pressure, etc. are complicated. A fine conductive pattern cannot be formed unless they are entangled. In particular, narrowing the pitch of semiconductor parts,
As the number of pins increases, it is difficult to form a fine land pattern corresponding to a pitch of 0.5 mm to 0.3 mm.

When soldering the surface mount component, cream solder is previously attached to the land portion of the wiring pattern, external electrodes are brought into contact with the cream solder to temporarily fix the surface mount component, and then the solder paste is passed through a reflow furnace. Reflow soldering, etc. is usually applied. To apply this cream solder to the land, dispenser coating or screen printing is applied. In addition to the above-mentioned various factors, solder mesh, flux content, viscosity of cream solder, etc. Since the above factors must be complicatedly entangled, it is extremely difficult to cope with the 0.3 mm pitch. In particular, when cream solder is used, solder balls are likely to occur during reflow, and soldering defects such as short circuits due to the solder balls may increase when the pitch is 0.3 mm.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a wiring pattern is finely formed including land portions having a narrow pitch, and a solder film for soldering surface mount components is properly and highly formed on the land portion of the wiring pattern. An object of the present invention is to provide a method for manufacturing a circuit board having a wiring pattern devised so as to be formed with high accuracy.

[0005]

In a method of manufacturing a circuit board having a wiring pattern according to claim 1 of the present invention,
A plate material that does not generate an impure gas, such as a ceramic substrate or a polyimide substrate, is used as a substrate, and an active metal material such as Cr or Ti is laminated on the plate surface of the substrate together with the underlying film to form C.
A conductive film is formed by sputtering or vacuum evaporation with a conductive metal material such as u, and then a resist film is applied to the conductive film to form a predetermined pattern of holes on the film surface by exposure and a phenomenon process. , A metal plating film is formed on the exposed conductive film inside the hole according to the hole having the predetermined pattern, and then the resist film is peeled off, and the metal plating film is used as a metal mask to make an excess. The conductive film and the base film are removed by etching from the plate surface of the substrate, and the metal plating film on the remaining conductive film is peeled off to form a fine wiring pattern.

In the method of manufacturing a circuit board having a wiring pattern according to the second aspect of the present invention, the metal material of the same material is laminated on the conductive film exposed inside the hole of the first aspect to increase the film thickness. As a conductive layer is formed by electrolytic plating.

In the method for manufacturing a circuit board having a wiring pattern according to the third aspect, a plate material such as a ceramic substrate or a polyimide substrate which does not generate an impure gas is used as a substrate, and the plate surface of the substrate is made of an active material such as Cr or Ti. Of a metallic material together with a base film, and by laminating on the base film, a conductive film is formed by sputtering or vacuum deposition with a conductive metal material such as Cu, and then a resist film is attached to the conductive film to expose. , Punching holes with a predetermined pattern by the phenomenon process are formed on the film surface, and a solder film is formed by laminating on the conductive film exposed inside the punching holes by plating according to the holes with the predetermined pattern, and then The resist film is peeled off, and the excess conductive film and the base film are removed by etching from the plate surface of the substrate by using the solder film as a metal mask. It is adapted to form a fine wiring pattern with a solder layer on the land portion of the solder film on the conductive film is left on the land portions by peeling from the other conductive film that.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a circuit board having a wiring pattern, wherein the metal material of the same material is laminated on the conductive film exposed inside the hole to increase the film thickness. Is formed by electrolytic plating.

In the method of manufacturing a circuit board having a wiring pattern according to the fifth aspect, S is formed by stacking on the conductive film exposed inside the punched hole in the third or fourth aspect.
A solder film of nPb or the like is deposited and formed by electroless plating.

In the method of manufacturing a circuit board having a wiring pattern according to the sixth aspect, N is laminated on the conductive film exposed inside the punched hole in the third or fourth aspect.
A solder film of SnPb or the like is deposited by electrolytic plating through a barrier layer of i or the like.

[0011]

In the method of manufacturing a circuit board having a wiring pattern according to the first aspect of the present invention, since the conductive film is formed by sputtering or vacuum evaporation using an active metal material as a base film, the conductive film is finally formed from the conductive film. The obtained wiring pattern can be formed by closely adhering to the substrate surface, and a plate material that does not generate an impure gas such as a ceramic substrate or a polyimide substrate when the conductive film is sputtered or vacuum-deposited is used as the substrate. There is no adverse effect on the formation of. The wiring pattern of the conductive film is formed by applying a predetermined pattern of holes formed in the resist film, and the metal plating film to be laminated and formed on the conductive film exposed inside the hole is used as a metal mask. Is formed by etching and removing from the plate surface of the substrate together with the base film. Therefore, even a wiring pattern having land portions with a narrow pitch can be formed finely by the exposure and development techniques of the resist film.

In the method of manufacturing a circuit board having a wiring pattern according to the second aspect of the present invention, the film thickness of the conductive film formed by sputtering or vacuum deposition is increased, so that the wiring pattern formed by the conductive film can be formed into a small electrical pattern. It can be formed to have a resistance film thickness.

In the method of manufacturing a circuit board having a wiring pattern according to a third aspect of the present invention, the solder film for soldering of surface-mounted components is landed at a narrow pitch by performing the same operation as the method according to the first aspect. Not only can it be formed extremely finely on the portion, but since the solder film is formed as a plating film, it can be formed on a smooth surface and the generation of solder balls can be prevented.

In the method for manufacturing a circuit board having a wiring pattern according to a fourth aspect of the present invention, the wiring pattern having a land with a solder film for soldering surface mount components is formed according to the second aspect. By performing the same operation as the method, the wiring pattern can be formed to have a small film thickness with electric resistance.

In the method for manufacturing a circuit board having a wiring pattern according to the fifth and sixth aspects of the present invention, since a solder film is formed by electroless or electrolytic plating, the soldering solder film of the surface mount component has an extremely smooth surface. It can be formed and the generation of solder balls can be prevented. Further, since the solder film is formed by plating in series with the step of increasing the thickness of the conductive film, it is possible to avoid complicating the step.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, FIGS. 1 and 2 show an embodiment in which a wiring pattern having a solder film for soldering surface mount components on a land portion is formed on a substrate surface in a final step. Show. 1 and 2 show different embodiments depending on whether electroless plating or electrolytic plating is used in the solder film forming process.

FIG. 1 shows a series of manufacturing steps including a step of forming the above-mentioned solder film by electroless plating.
Based on this, a method of manufacturing a circuit board having a wiring pattern will be described.

First, in the first step, a base film 2 and a conductive film 3 are formed by sputtering or vacuum evaporation using a ceramic substrate such as an alumina substrate or a flexible polyimide substrate 1. Among them, the base film 2 is made of Cr, T
It is formed from an active metal material such as i to a film thickness of about 500 to 1000 Å, and this base film 2 can improve the adhesion strength of the conductive film 3 to the substrate 1. The conductive film 3 is made of a conductive metal material such as Cu and has a thickness of several thousand Å, for example, 5
It is formed with a film thickness of about 000Å. Even if sputtering or vacuum deposition is applied in this step, by selecting a substrate such as a ceramic substrate or a polyimide substrate 1 which does not generate an impure gas, the conductive film 3 formed in the final step as a wiring pattern is adversely affected. Never.

Next, a resist film 4 is laminated on the conductive film 3, and a hole 5 having a predetermined pattern is formed on the film surface through an exposure and development process. As the resist film 4, a dry film having a film thickness of about 30 to 50 μm is used, and the holes 5 are formed by photomasking having a predetermined light transmitting pattern.
It can be formed by covering the film surface of the above with a light irradiation treatment. The punched holes 5 are formed in the same pattern as the wiring pattern obtained in the final step, and can be accurately formed even in accordance with a wiring pattern including land portions with a narrow pitch. By forming this hole 5, the hole 5
The conductive film 3 is exposed inside.

After patterning the resist film 4 by the punching holes, a conductive layer 6 for increasing the film thickness of the conductive film 3 is formed by electrolytic plating with the same conductive metal material as Cu such as the conductive film 3. In consideration of the electric resistance of the wiring pattern, the conductive layer 6 increases the thickness of the conductive film 3 by a thickness of approximately 30 to 50 μm. It can be omitted. A solder film 7 of SnPb or the like is deposited and formed to a thickness of about 20 μm by electroless plating via the conductive layer 6. The conductive layer 6 including the solder film 7 is formed by laminating it on the conductive film 3 inside the hole 5.

Instead of this electrolytic plating, electrolytic plating can be applied to form the solder film 7. In that case, in order to prevent the conductive film 3 or the conductive layer 6 from being soldered, Ni is used as a solder barrier layer as shown in the embodiment of FIG.
After forming the plating film 8 of 1 to 2 .mu.
The solder film 7 of nPb or the like may be formed by electrolytic plating.

After forming the solder film 7, the resist film 4 is formed.
By peeling off, each of the films 6, 7 or 8 laminated on the conductive film 3 is exposed to the outside on the plate surface of the substrate 1.
The substrate 1 is subjected to a process of removing the excess conductive film 3 and the base film 2 from the substrate surface by wet etching using the solder film 7 as a metal mask, and a wiring pattern corresponding to the solder film 7 is formed into the conductive film 3 and the conductive film. Formed in layer 6. The solder film 7 is left only on the land portions of the wiring patterns 3 and 6 and peeled off from the other pattern surfaces. The peeling of the solder film 7 can be easily performed by applying wet etching after applying a resist in advance between the land portions or between the lands.

When the wiring patterns 3 and 6 are formed on the plate surface of the substrate 1 in this way, a land pattern having a pitch of 0.3 mm or less is formed by highly accurate patterning by exposure using the resist film 4 and a phenomenon process. Even the wiring patterns 3 and 6 can be formed extremely finely. Further, since the wiring patterns 3 and 6 are formed on the base film 2 of an active metal material as a base, they can be formed on the plate surface of the substrate 1 with high adhesion strength.

Since the solder film 7 is formed by the plating process, the surface can be formed as a smooth surface having no unevenness, and it is possible to prevent terminal floating or the like of the surface mount component. Further, since solder balls are not generated during reflow, it is possible to prevent an electrical short circuit phenomenon from occurring in the land portion having a narrow pitch. Furthermore, since the solder film 7 can be formed without printing with cream solder, it is possible to reduce the overall cost, including the reduction of setup time and condition setting time required when changing the type of product.

On the circuit board having this wiring pattern, the flux 9 is applied by solid coating or printing so as to cover the solder film 7 formed on the lands of the wiring patterns 3 and 6 as shown in FIG. The external terminals of the surface mount component E can be temporarily fixed by arranging them at positions corresponding to 7, and then the surface mount component E can be sent to a reflow furnace and fixed by soldering.

In the above-described embodiment, the wiring patterns 3 and 6 having the solder film 7 on the land portion are formed on the substrate surface. However, the method for manufacturing a circuit board having this wiring pattern is only the wiring pattern. Can also be applied to form In that case, instead of the solder film 7, an appropriate metal material serving as a metal mask may be formed by laminating it on the conductive film 3 or the conductive layer 6, and the metal mask may be entirely removed in the final step.

[0027]

As described above, according to the method of manufacturing a circuit board having a wiring pattern according to the present invention, even a wiring pattern having land portions with a narrow pitch while maintaining proper electrical characteristics can be used for mounting components. It is possible to form a fine soldering film with a wiring pattern provided in the land portion, and the cost can be reduced because the soldering film is formed without relying on cream solder. Since the solder film can be formed so as not to generate solder balls having a smooth surface, the surface mount component can be soldered and fixed with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a method of manufacturing a circuit board having a wiring pattern according to an example of the present invention in order of steps.

FIG. 2 is an explanatory diagram sequentially showing a method of manufacturing a circuit board having another example of a wiring pattern which is partially different in the solder film forming step according to the present invention from the solder film forming step.

FIG. 3 is an explanatory view showing a surface mount component temporarily fixed to a circuit board manufactured by the method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Underlayer film 3 Conductive film 4 Resist film 5 Holes 6 Conductive layer 7 Solder film 8 Solder film barrier layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Genichi Watanabe 1-13-1, Nihonbashi, Chuo-ku, Tokyo Inside TDC Corporation

Claims (6)

[Claims] 1. A plate material, such as a ceramic substrate or a polyimide substrate, which does not generate an impure gas, is used as a substrate, and C is provided on the plate surface of the substrate.
An active metal material such as r, Ti or the like, together with a base film, is laminated on the base film to form a conductive film of a conductive metal material such as Cu by sputtering or vacuum deposition, and then a resist film is formed on the conductive film. A hole with a predetermined pattern is formed on the film surface by exposure and a phenomenon process, and a metal plating film is formed according to the hole with the predetermined pattern by laminating on a conductive film exposed inside the hole. After the formation, the resist film is peeled off, the surplus conductive film and the base film are removed by etching from the plate surface of the substrate by using the metal plating film as a metal mask, and the metal plating film on the remaining conductive film is peeled off. A method for manufacturing a circuit board having a wiring pattern, characterized in that a fine wiring pattern is thereby formed. 2. The conductive film exposed inside the punched hole is laminated, and a metal material of the same material that increases the film thickness is formed by electroplating as a conductive layer. 1. A method of manufacturing a circuit board having a wiring pattern of 1. 3. A plate material, such as a ceramic substrate or a polyimide substrate, which does not generate an impure gas, is used as a substrate, and C is placed on the plate surface of the substrate.
An active metal material such as r, Ti or the like, together with a base film, is laminated on the base film to form a conductive film of a conductive metal material such as Cu by sputtering or vacuum deposition, and then a resist film is formed on the conductive film. To form a hole with a predetermined pattern on the film surface by exposure and a phenomenon process, and stack it on the conductive film exposed inside the hole to plate a solder film according to the hole with the predetermined pattern. Formed by processing, and then the resist film is peeled off, the surplus conductive film and the base film are removed by etching from the plate surface of the substrate using the solder film as a metal mask, and the solder film on the remaining conductive film is landed. Wiring characterized in that a fine wiring pattern having a solder film in the land portion is formed by leaving the solder film in the land and peeling it from other conductive film. Method of manufacturing a circuit board having a turn. 4. A metal material of the same material that increases the film thickness is formed by electroplating by laminating it on a conductive film exposed inside the punched hole.
A method for manufacturing a circuit board having a wiring pattern. 5. The wiring pattern according to claim 3, wherein a solder film of SnPb or the like is deposited and formed by electroless plating by laminating it on a conductive film exposed inside the punched hole. A method of manufacturing a circuit board having a. 6. The conductive film exposed inside the hole is laminated, and a solder film of SnPb or the like is deposited by electrolytic plating through a barrier layer of Ni or the like. A method of manufacturing a circuit board having the wiring pattern according to item 3 or 4.