JP2013162007A - Production method of fine wiring pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a process suitable for production of a fine wiring pattern, by solving the problem of thinning due to undesired removal of a wiring part, in the production process of a fine wiring pattern using a semi-additive method.SOLUTION: When removing a metal film exposed to a non-wiring part on an insulation substrate after removing a resist coat formed at a part where formation of wiring is not required, a step for supplying an etching liquid (or a process liquid used before etching and accelerating the etching, a process liquid for removing the residue of an electroless copper plating layer, or the like) by ink jet system is employed.

Description

The present invention relates to a method for suitably manufacturing a fine wiring pattern of a printed wiring board.

Printed wiring boards are widely used for mounting electronic components, semiconductor elements, and the like. With recent demands for downsizing and higher functionality of electronic devices, printed wiring boards are desired to have higher circuit density and thickness.

As a method for producing this high-density printed wiring board, a method called a semi-additive method is employed. An example of a printed wiring board using a conventional semi-additive method will be described with reference to FIG.

An insulating substrate 1 as shown in FIG. Then, after applying a plating catalyst 2 such as a palladium compound to the surface of the insulating substrate 1 as shown in FIG. 2 (b), electroless plating is performed using the plating catalyst 2 as a core, as shown in FIG. 2 (c). A thin first metal film 3 is formed on the entire surface of the insulating substrate 1.

Next, as shown in FIG. 2 (d), after the resist film 4 is formed on the surface of the first metal film 3 except for the part where the circuit is to be formed, electroplating is performed, and the first metal is formed. A second metal film 5 is formed on the surface of the portion where the film 3 is exposed, as shown in FIG.

Next, after removing the resist film 4 as shown in FIG. 2F, the unnecessary first metal film 3 is removed by etching as shown in FIG. At this time, the surface of the second metal film 5 is also etched by about the thickness of the first metal film 3 to reduce the thickness.
Next, the printed wiring board is manufactured by performing nickel plating or gold plating on the surface of the second metal film 5 as necessary.
Thus, in the semi-additive method, the portion removed in the etching step is a thin metal film (first metal film 3), and a subtractive that forms a circuit by etching a metal foil thicker than the first metal film 3 Compared with a method called a method, it is possible to form a fine circuit with high accuracy.

According to Patent Document 1, an alloy plating layer containing a metal different from copper or one or more of these metals is formed on the surface of the second metal film 5 at the stage of FIG. Electrolytic copper plating is applied to the surface of the etching barrier plating layer to form a wiring having a conductive layer including an electroless copper plating layer, an etching barrier metal plating layer, and an electrolytic copper plating layer. A method of forming a wiring pattern by etching away an exposed unnecessary electroless copper plating layer has been proposed.
In this method, the number of steps increases and the method is not efficient, and since the etching barrier layer is only the surface of the second metal film 5, an effect as an etching barrier layer other than the surface cannot be expected.

JP 2006-024902 A

When manufacturing by the semi-additive method, even if the first metal film 3 is removed by etching, the plating catalyst 2 tends to remain on the surface of the insulating substrate 1 as shown in FIG. There was a problem that the property was easily lowered. Therefore, the plating catalyst 2 on the surface of the insulating substrate 1 is also removed at the same time by etching and removing the first metal film 3 using an etching solution having a high etching ability.

However, when the first metal film 3 is removed by etching using this etching solution having a high etching ability, the surface and side surfaces of the second metal film 5 due to the in-plane position of the insulating substrate 1 are etched, and the circuit is thinned. There was a problem of side etching. This problem causes a decrease in reliability due to etching ion residues on the surface and side surfaces of the circuit as well as deterioration in electrical characteristics.

In view of the above problems, the present invention eliminates the problem of thinning due to undesired removal of the wiring (second metal film 5) in the removal process of the first metal film 3 and the plating catalyst 2, and provides a fine wiring pattern. The present invention proposes a process suitable for manufacturing the above.

In the present invention, in a method for manufacturing a fine wiring pattern using a semi-additive method,
After removing the resist film formed at the place where wiring formation is not necessary, in removing the metal film exposed to the non-wiring part on the insulating substrate, etching is performed by an inkjet method (or etching in a later process prior to etching). A liquid for promoting / assisting the liquid).

  In the process of removing unnecessary metal films, part of even unnecessary wiring parts may be removed, which can completely eliminate the problem in the production of fine wiring patterns using the semi-additive method. Although considered difficult, the present invention reduces the problem of thinning due to unwanted removal of fine wiring.

Explanatory drawing which shows the manufacturing method of the printed wiring board regarding this invention. Explanatory drawing which shows the manufacturing method of the conventional printed wiring board.

A method for manufacturing a printed wiring board according to the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing a printed wiring board manufacturing method according to the present invention in the order of steps.

The insulating substrate 1 used in the present invention is not particularly limited as long as it is an insulating plate.
For example, there are thermosetting resins such as epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, and polyphenylene ether resin.
In addition, the above-mentioned thermosetting resin is used for a plate made of these thermosetting resins containing inorganic fillers, inorganic fibers such as glass, cloths made of organic fibers such as polyester, polyamide, and cotton, and base materials such as paper. For example, a plate adhered with a ceramic plate, a ceramic plate, or the like.
The insulating substrate 1 may have a conductor circuit, a through hole, or the like.

The plating catalyst 2 is not particularly limited as long as it functions as a catalyst for electroless plating such as copper or nickel.
By depositing metal around the plating catalyst 2 to connect the plating catalysts 2 to form a metal film on the insulating portion, or by depositing on the insulating portion, the insulating portion is made conductive and the conductivity is increased. Examples thereof include those having conductivity that are used in a method generally used for direct plating (direct plating) to form a metal film on an insulating portion. Examples include those containing palladium, those containing palladium and tin, those containing carbon such as carbon and graphite, those containing a copper complex, and those containing a conductive polymer.

As shown in FIG. 1C, a thin first metal film 3 is formed on the entire surface of the insulating substrate 1. For example, examples of the method for forming the first metal film 3 include electroless plating and sputtering. As this 1st metal membrane | film | coat 3, since it is necessary to be excellent in the ease of an etching and electroconductivity at a next process, copper is preferable.

Next, as shown in FIG. 1 (d), after the resist film 4 is formed on the surface of the first metal film 3 except the part where the circuit is to be formed, the first metal film 3 is exposed. A second metal film 5 is formed on the surface as shown in FIG. For example, the method for forming the second metal film 5 includes electrolytic plating, electroless plating, and the like. In addition, the thickness of the second metal film 5 formed at this time needs to be thinner than the thickness of the resist film 4. This is because when the resist film 4 is removed as shown in FIG. 1 (f), the resist film 4 is difficult to be removed if the resist film 4 is thicker than the second metal film 5.

The resist film 4 used in the present invention is particularly limited as long as it resists the plating solution for forming the second metal film 5 and is difficult to form the second metal film 5 on the surface when this plating is performed. For example, a liquid photosensitive resin or a sheet-like photosensitive film is formed on the entire surface of the first metal film 3, and then exposed to a circuit shape. Examples include those formed by removing a resin or a photosensitive film.

Next, the resist film 4 is removed as shown in FIG. For example, examples of the removing liquid (stripping liquid) for removing the resist film 4 include alkali or solvent-type stripping liquid.

Next, as shown in FIG. 1G, unnecessary portions of the first metal film 3 are removed by etching.
For example, as a removing solution (etching solution) for removing an unnecessary portion of the first metal film 3, an alkaline etching solution (non-chloride / no matter whether it is chloride) or the like can be given.
In the prior art, when the first metal film 3 exposed in the non-wiring portion is removed by etching, the removing solution (etching solution) is uniformly supplied to the entire surface of the printed wiring board including the wiring portion, and thus the removal is required. The surface and side surface of the second metal film 5 that is not present are also etched, leading to thinning of the wiring.
In the present invention, in the process from FIG. 1 (f) to FIG. 1 (g), the removal liquid (etching liquid) in a fine region is selectively and preferentially promoted to remove the portion requiring etching. In order to supply the above, spraying by an ink jet method is adopted.

Alternatively, prior to performing etching by an existing method (spraying, dipping, etc.) that does not employ an ink jet method, a method of spraying a treatment liquid that promotes etching in advance on the portion that needs to be etched by an ink jet method is employed. .
In order to spray the etching liquid and the processing liquid on the non-wiring portion (the gap between the second metal coatings 5) accurately and intensively, there is an ink jet system capable of controlling the spray area in a minute range by nozzle control. Is preferred.

Next, as shown in FIG. 1H, the plating catalyst 2 remaining on the surface of the insulating substrate 1 is removed.
If the plating catalyst 2 remaining on the surface of the insulating substrate 1 is removed in this manner, the insulation between the circuits is improved, so that a printed wiring board having particularly high reliability is preferable.

Examples of a method for removing the plating catalyst 2 remaining on the surface of the insulating substrate 1 include a method of removing the plating catalyst 2 by immersing it in a solution that can be dissolved.
For example, a method of bringing the potassium permanganate solution or the sodium permanganate solution into contact with the insulating substrate 1 by spraying or dipping may be mentioned.
This potassium permanganate solution or sodium permanganate solution is generally used in a smear removing step after through-hole formation in a printed wiring board processing step.

In addition, also in the removal process of the residual plating catalyst 2 in FIG.1 (h), it is suitable in order to avoid the bad influence to a wiring part to employ | adopt the spray of the process liquid by an inkjet system.

As shown in FIG.1 (c), the electroless copper plating layer 3 was formed in the thickness of 1.0 micrometer by the electroless copper plating on the surface of the epoxy insulation resin board | substrate 1. As shown in FIG.
Next, as shown in FIG. 1 (d), a surface of the electroless copper plating layer 3 is coated with a 25 μm thick dry resist, and a plating resist pattern 4 having a line / space of 10/10 μm is formed by exposure and development. Formed.
Next, as shown in FIG. 1E, electrolytic copper plating was performed using a copper sulfate bath to form an electrolytic copper plating layer 5 having a thickness of 15 μm to form a wiring pattern.
Next, as shown in FIG. 1F, the etching plating resist pattern 4 was removed by a spray method using a hydrogen peroxide / sulfuric acid based etching solution.

After performing the process up to the step shown in FIG. 1 (f), a hydrogen peroxide / sulfuric acid-based etching solution is applied by an ink jet apparatus to remove the electroless copper plating layer 2 exposed between the wiring portions, and shown in FIG. 1 (g). It was in a state.

Next, from the state of FIG. 1 (g), a potassium permanganate solution is applied by an ink jet device, and unnecessary electroless copper plating layer 2 exposed between the wiring portions on the surface of the insulating substrate 1 is removed to remove FIG. h).

When spraying an etching solution (or a treatment solution for promoting etching performed before etching, a treatment solution for removing the residue of the electroless copper plating layer, etc.) by an inkjet apparatus, the wiring portion is etched. Drive the ink discharge nozzle (inkjet head) so that the liquid does not adhere and is selectively supplied between the wires, and L / S = 50μm / 50μm (or less than 10μm / 10μm) Etching solution is discharged so as to draw a line in the central portion between the wirings.
A treatment liquid having a viscosity (about 20 mPa · s or less) that can be discharged from an ink discharge nozzle (inkjet head) is applicable, and not only the removal of the electroless copper plating layer, but also the cleaning of the surface of the insulating substrate or the wiring portion. You may employ | adopt the target process liquid.
In addition, as the processing liquid supply area is finer, the effect of spraying the etching liquid by the ink jet apparatus is improved.

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... Plating catalyst 3 ... 1st metal film 4 ... Resist film 5 ... 2nd metal film

Claims (3)

In the method of manufacturing a fine wiring pattern using the semi-additive method,
After removing the resist film formed at a place where wiring formation is unnecessary, the method includes a step of supplying an etching solution by an ink jet method when removing the metal film exposed to the non-wiring portion on the insulating substrate. A method of manufacturing a wiring pattern. In the method of manufacturing a fine wiring pattern using the semi-additive method,
Before removing the metal film exposed on the non-wiring portion on the insulating substrate by wet etching after removing the resist film formed at a place where wiring formation is unnecessary, a liquid that promotes etching by an ink jet method prior to the etching. A method for producing a fine wiring pattern comprising the step of supplying In the method of manufacturing a fine wiring pattern using the semi-additive method,
After removing the resist film formed at the place where wiring formation is unnecessary, after removing the metal film exposed to the non-wiring part on the insulating substrate, it was given in advance as a catalyst when forming the metal film by electroless plating And a method of producing a fine wiring pattern comprising a step of supplying a treatment liquid comprising a potassium permanganate solution or a sodium permanganate solution by an ink jet method when removing the plating catalyst remaining on the surface of the insulating substrate. .