JPH1197824A - Manufacture of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the formation of projections or unevenness on the surface of a circuit pattern and thereby avoid a defective pattern by placing an insulating substrate with a plating base layer faced downward and having a laser irradiated from below the insulating substrate. SOLUTION: A plating base layer 2 is formed on the surface of an insulating substrate 1, and laser beam is irradiated on at least an outline section 3 of a circuit pattern for removing the plating base layer 2 in the outline section 3. Then, a conductive metal film 4 is formed by plating on the plating base layer 2 left out for the circuit pattern. Furthermore, unwanted part of the plating base layer 2 is removed to complete a circuit board. After that, the insulating substrate 1 is placed with the plating base layer faced downward, and laser beam is irradiated on the insulating substrate 1 from below. As a result of this method, no projection or unevenness is formed on the surface of the conductive metal film due to scattered matters, and defective pattern is hardly generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a circuit board on which a conductive metal film serving as a circuit pattern is formed by plating. And a method for manufacturing a circuit board.

[0002]

2. Description of the Related Art As a conventional method of manufacturing a circuit board, there is a method shown in FIG. 4 described in Japanese Patent Application Laid-Open No. 7-66533. In this method of manufacturing a circuit board, (A)
As shown in (B), fine irregularities are formed on an insulating base material 1 as shown in FIG. 1B, and then a plating underlayer 2 is formed as shown in (C). Then, as shown in (D), the laser is irradiated from above with the plating underlayer 2 facing upward,
The plating underlayer 2 in the laser-irradiated portion is removed, and as shown in (E), electroplating or the like is performed on the plating underlayer 2 in a portion other than the laser-irradiated portion to become the remaining circuit pattern, thereby forming a conductive metal film. 4 are formed.

In such a method of manufacturing a circuit board, since a pattern is not formed using a resist, a complicated resist exposure and development step can be omitted, and the insulating base material 1 has a three-dimensional shape. It's an easy way to do it. Also, in some cases, laser irradiation only needs to be performed on the boundary area between the circuit part and the non-circuit part,
The laser irradiation only needs to be performed in a very narrow area, and it is not necessary to irradiate the entire surface with the laser, so that the manufacturing time can be reduced.

[0004]

However, in the above-mentioned conventional example, when removing the plating underlayer 2 by irradiating a laser, scattered matters such as droplets generated by the irradiation of the laser are removed. May adhere to the plating base layer 2. The scattered matter adhered in this manner causes projections or irregularities to be formed on the surface of the plated conductive metal film 4 when plating is performed in the next step, which is one of the causes of failure of the circuit board. It is easy to become.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a circuit board in which projections or irregularities are less likely to be formed on the surface of a circuit pattern and pattern defects are less likely to occur. To provide a production method.

[0006]

According to the first aspect of the present invention, there is provided a plating base layer on a surface of an insulating substrate.
And irradiating a laser to at least the contour portion 3 serving as a circuit pattern to remove the plating base layer 2 of the contour portion 3 and leaving a portion of the plating base layer 3 of the remaining circuit pattern.
In the method for manufacturing a circuit board for forming a circuit pattern by forming a conductive metal film 4 by plating, the insulating base 1 is disposed with the plating base layer 2 facing downward. It is characterized by irradiating a laser.

In such a method of manufacturing a circuit board, a laser is irradiated from below onto the plating underlayer 2 and the plating underlayer 2 is removed. Splatters easily fall down,
It is difficult to adhere again to the plating underlayer 2.

According to a second aspect of the present invention, in the first aspect, the insulating base material 1 is formed using a material having a high laser transmittance, and the laser is irradiated from above the insulating base material 1. It is configured as a feature.

In such a method of manufacturing a circuit board, a laser can be applied to the plating base layer 2 by allowing the insulating base material 1 to pass therethrough. At this time, since the plating base layer 2 is located on the lower surface of the insulating base material 1, the scattered matter easily falls downward and is less likely to re-attach to the plating base layer 2 as in the case of the first aspect of the present invention. I have.

According to a third aspect of the present invention, a plating base layer 2 is formed on the surface of an insulating base material 1, and at least a contour portion 3 serving as a circuit pattern is irradiated with a laser beam. In a method of manufacturing a circuit board for forming a circuit pattern, a conductive metal film 4 is formed by plating on a portion of the plating underlayer 2 where a remaining circuit pattern is to be formed. Forming layer 5,
Laser irradiation is performed from above the barrier layer 5, and after the barrier layer 5 is removed, plating is performed.

In such a circuit board manufacturing method, scattered matters such as droplets generated by laser irradiation adhere to the barrier layer 5, but the scattered matters adhere to the barrier layer 5.
At the same time, it is removed from the plating base layer 2 and does not adhere to the plating base layer 2.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an explanatory view showing one method of manufacturing a circuit board according to this embodiment, and shows a state in the middle of each step as a perspective view or a sectional view in (A) to (E). It is.

As shown in this figure, in this manufacturing method,
As shown in (A), a plating base layer 2 is formed on the surface of an insulating base material 1 and, as shown in (B) to (C), at least a contour portion 3 serving as a circuit pattern is irradiated with a laser, The plating base layer 2 of the contour portion 3 is removed. And
As shown in (D), a circuit pattern is formed by plating a conductive metal film 4 on the plating base layer 3 in a portion to be a remaining circuit pattern. further,
As shown in (E), the circuit board is completed by removing unnecessary portions of the plating underlayer 2.

In this manufacturing method, as shown particularly in FIG. 2B, the insulating substrate 1 is disposed with the plating base layer 2 facing downward, and a laser is irradiated from below the insulating substrate 1. I am trying to do it. In this case, an electromagnetic wave can be used as the laser.

A more specific example will be described below. As the insulating base material 1, a material formed by injection molding or the like of a synthetic resin material such as polyimide, polyetherimide, polyamide, and liquid crystal polymer is preferably used. In addition, alumina ceramics or a composite material using a metal substrate as a core material may be used, and substrates made of various insulating materials can be used. Also,
Although a flat plate is shown, it may be a three-dimensional plate.

Next, after the surface of the insulating base material 1 is degreased with an alkaline cleaning agent, the surface of the insulating base material 1 is subjected to plasma treatment to activate the surface and roughen the surface. . Alternatively, fine roughening may be performed by chemical etching. Then, a metal film such as copper, silver, gold, nickel, platinum, or palladium is formed on the surface of the insulating base material 1 thus treated by sputtering, vacuum deposition, chemical catalyst activation treatment, or the like,
This metal film is used as the plating underlayer 2. This plating base layer 2 is preferably formed to a thickness of about 0.1 to 2.0 μm.

The laser irradiation for removing the plating underlayer 2 is preferably a second harmonic YAG laser, a YAG laser, an excimer laser, or the like. By operating such a laser with a galvanomirror, the plating underlayer 2 is removed. In this case, the operation is performed so as to irradiate the laser only to the contour portion 3 serving as the circuit pattern, so that the operation time can be reduced. Needless to say, when the area of the portion that becomes the circuit pattern is large, the entire surface of the portion that does not become the circuit pattern can be irradiated with the laser. As described above, by irradiating the entire surface of the portion that does not become the circuit pattern with the laser, the step of forming the conductive metal film 4 and then removing the unnecessary portion of the plating base layer 2 can be omitted. Simplified.

In the step of forming the conductive metal film 4 after the laser irradiation, electroplating is performed. As the electroplating, for example, using a copper sulfate plating bath (copper sulfate 80 g / liter, sulfuric acid 180 g / liter, containing trace amounts of chlorine, brightener, etc.)
Power is supplied to the plating base layer 2 in a portion to be a circuit pattern to form a copper metal film. Further, an electric nickel plating is performed on the copper using a Watt bath (including 270 g / liter of nickel sulfate, 50 g / liter of nickel chloride, 40 g / liter of boric acid, and a trace amount of brightener) to form a nickel metal film. Then, a gold metal film is formed by performing electrogold plating using a commercially available electrogold plating bath, and the conductive metal film 4 including three layers of copper, nickel, and gold can be formed. The plating base layer 2 remaining in portions other than the portion that becomes the circuit pattern may be removed using a soft etching solution or the like.

Although the above description is for the case of electroplating, it may be performed by electroless plating in some cases. In the case of this electroless plating, it is preferable to immerse the insulating base material 1 in an electroless plating solution after leaving only the plating base layer 2 in a portion to be a circuit pattern.

In the method for manufacturing a circuit board as described above, a laser is directly applied to the plating underlayer 2 from below to remove the plating underlayer 2, so that droplets and the like generated by the laser irradiation are removed. Splatters easily fall down,
It is difficult to adhere again to the plating underlayer 2. Therefore, even if plating is performed thereafter, projections or irregularities caused by the reattached scattered matter are not formed on the surface of the conductive metal film 4, and pattern defects are less likely to occur, and the manufacturing yield is improved. Can be.

FIG. 2 is a cross-sectional view showing another example of the method of manufacturing a circuit board according to this embodiment. This figure shows the step (B) in FIG.

In this manufacturing method, the insulating base material 1 is formed using a material having high laser transmittance. Examples of such a material include polyimide and polyetherimide. Except for the steps shown in this figure, the steps can be performed in exactly the same manner as described with reference to FIG.

In other words, in this manufacturing method, the laser is irradiated from above the insulating base 1 using the insulating base 1 made of a material having particularly high laser transmittance.

Therefore, in this circuit board manufacturing method,
The laser is transmitted through the insulating base material 1 and is irradiated on the plating base layer 2. At this time, since the plating base layer 2 is on the lower surface of the insulating base material 1, as in the case of FIG.
The scattered matter is likely to fall downward, and is less likely to reattach to the plating underlayer 2. In addition, since the laser can be irradiated from above the insulating base material 1, there is an advantage that the laser can be easily irradiated.

FIGS. 3A and 3B are cross-sectional views showing still another example of the method of manufacturing a circuit board according to this embodiment. FIGS. 3A and 3B are (B) and (B) in FIG. This corresponds to the step C).

In this manufacturing method, as shown in FIG.
The barrier layer 5 is formed on the plating base layer 2 of the insulating base material 1 before the laser irradiation, and the laser is irradiated from above the barrier layer 5. That is, the plating base layer 2 is removed together with the barrier layer 5. Then, as shown in (B), after the remaining barrier layer 5 is removed, plating is formed on the plating base layer 2 in a portion to be a circuit pattern.

As the barrier layer 5 as described above, a film such as silicon dioxide can be exemplified. Such a film of silicon dioxide or the like is formed by vacuum evaporation or CVD, preferably to a thickness of several hundred angstroms. The barrier layer 5 can be removed by dissolving it with hydrofluoric acid or the like.

Therefore, in such a method of manufacturing a circuit board, scattered matters such as droplets generated by laser irradiation adhere to the barrier layer 5, and the scattered matter adheres to the barrier layer 5 together with the barrier layer 5. It is removed from the plating base layer 2 and no longer adheres to the plating base layer 2. Also in this case, it is possible to irradiate the laser from above, so that the work can be easily performed.

[0030]

According to the first aspect of the present invention, a laser is directly applied to the plating underlayer from below, and the plating underlayer is removed, so that scattered objects such as droplets generated by the laser irradiation. Is easy to fall down and is hard to re-adhere to the plating underlayer. Therefore, even if plating is performed thereafter, protrusions or irregularities caused by the re-attached scattered matter are not formed on the surface of the conductive metal film,
Pattern defects are less likely to occur, and the manufacturing yield can be improved.

According to the second aspect of the invention, in addition to the effect of the first aspect, the laser can be irradiated from above the insulating base material, so that the laser can be easily irradiated.

According to the third aspect of the invention, scattered matters such as droplets generated by the laser irradiation adhere to the barrier layer, and the scattered matters adhered together with the barrier layer are removed from the plating base layer. Therefore, it does not adhere to the plating underlayer. Therefore, projections or irregularities caused by the re-adhered scattered matter are not formed on the surface of the conductive metal film, pattern defects are less likely to occur, and the production yield can be improved. In addition, since the laser can be irradiated from above the insulating base material, the laser can be easily irradiated.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one method of manufacturing a circuit board according to an embodiment of the present invention, and shows the state of each step as a perspective view or a sectional view in (A) to (E). .

FIG. 2 is a cross-sectional view showing another example of the method of manufacturing the circuit board according to the embodiment;

FIG. 3 is a cross-sectional view showing still another example of the method of manufacturing a circuit board according to the embodiment, and shows a state in the middle of the process in (A) or (B).

FIG. 4 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating base material 2 Plating base layer 3 Contour part 4 Conductive metal film 5 Barrier layer

Claims (3)

[Claims] 1. A plating base layer is formed on the surface of an insulating base material, and at least a contour part to be a circuit pattern is irradiated with a laser to remove the plating base layer in the contour part to form a remaining circuit pattern. In a method of manufacturing a circuit board for forming a circuit pattern by forming a conductive metal film on a portion of a plating base layer by plating, an insulating base is disposed with the plating base layer facing downward, and the insulating base is disposed below the insulating base. A method for manufacturing a circuit board, comprising irradiating a laser beam from a substrate. 2. The method for manufacturing a circuit board according to claim 1, wherein an insulating base material is formed using a material having a high laser transmittance, and a laser is irradiated from above the insulating base material. 3. A plating base layer is formed on the surface of the insulating base material, and at least a contour portion serving as a circuit pattern is irradiated with a laser to remove the plating base layer in the contour portion, thereby forming a remaining circuit pattern. In a method of manufacturing a circuit board for forming a circuit pattern by forming a conductive metal film on a portion of a plating base layer by plating, a barrier layer is formed on the plating base layer, and laser is irradiated from above the barrier layer. And
A method for manufacturing a circuit board, wherein plating is performed after removing the barrier layer.