JP2001237520A - Method for manufacturing circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform electroplating without performing any electroless copper plating and at the same time provide a method for manufacturing a circuit substrate where electrolyte is not contaminated in electroless plating. SOLUTION: A nickel film 2 is formed on the surface of an insulation substrate 1 by the dry plating method, electromagnetic waves 11 are applied to the nickel film 2 for eliminating a circuit contour 10, thus separating and forming a circuit formation part 8 and a circuit non-formation part 9, forming a nickel thick film 3 on the surface of the circuit formation part 8 by the electroplating method, performing the etching treatment of the circuit non-formation part 9, then forming a copper layer 4 on the surface of the nickel thick film 3 by the electroplating method, and forming a circuit board.

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 for an electronic circuit.

[0002]

2. Description of the Related Art A method of manufacturing a circuit board as described in Japanese Patent Application Laid-Open No. 7-66533 has been proposed.

In this method of manufacturing a circuit board, a plating underlayer is formed on the surface of an insulating substrate, a boundary region of a circuit portion is removed by irradiating electromagnetic waves, and plating is performed on the plating underlayer of the circuit portion. To form a circuit board.

In such a method of manufacturing a circuit board, since the electromagnetic wave light is irradiated at least along a boundary region between the circuit portion and the circuit portion of the insulating substrate, the electromagnetic wave is applied to the entire surface of the region where the circuit is not formed. A circuit pattern can be formed without the need to remove light. Even if plating is formed on the plating underlayer in the circuit non-formation portion, the circuit portion is separated and insulated from the circuit portion by irradiation of electromagnetic wave light, and there is no particular problem in the circuit performance of the circuit board.

[0005]

However, in the above-described conventional method for manufacturing a circuit board, when electroless copper plating is performed when plating is formed on a plating underlayer, the waste liquid and the plating solution are not adversely affected on the environment. There is a problem that a wastewater treatment facility is required.In addition, when electrolytic plating is performed, a plating underlayer made of a metal or the like in the electrolytic solution begins to melt, and the electrolytic solution is contaminated. There is a problem of mixing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to perform electrolytic plating without performing electroless copper plating, and to provide a circuit board that is not contaminated with an electrolytic solution during electrolytic plating. It is to provide a manufacturing method of.

[0007]

According to the first aspect of the present invention, a nickel film is formed on a surface of an insulating substrate by dry plating, and the nickel film is irradiated with electromagnetic waves to form a circuit profile. The circuit forming portion and the circuit non-forming portion are separated and formed by removing the portion, a nickel thick film is formed on the surface of the circuit forming portion by electroplating, and the circuit non-forming portion is etched, and then the surface of the nickel thick film is etched. And a circuit board formed by forming a copper layer by electroplating.

In such a method of manufacturing a circuit board, since the copper layer is formed on the surface of the circuit formation portion by electroplating, there is no need to perform electroless plating. Therefore, wastewater and wastewater treatment equipment for the electroless plating solution is not required, and it is environmentally friendly. Also, since a nickel thick film is formed on the surface of the circuit forming portion by electroplating and the non-circuit forming portion is etched, the nickel film on the circuit non-forming portion is removed, and the surface of the nickel thick film is plated by electroplating. Thus, when forming a copper layer, the nickel of the nickel film can be prevented from being dissolved in the electrolytic solution, and contamination of the electrolytic solution can be prevented.

In the invention according to the second aspect, a nickel film and a copper film are formed on the surface of the insulating substrate by dry plating, and the nickel film and the copper film are irradiated with electromagnetic waves to form a circuit. The circuit forming portion and the circuit non-forming portion are separately formed by removing the contour portion, and a circuit board is formed by forming a copper layer by electroplating on the surface of the circuit forming portion. I have.

In such a method of manufacturing a circuit board, since the copper layer is formed on the surface of the circuit forming portion by the electroplating method, there is no need to perform electroless plating. Therefore, wastewater and wastewater treatment equipment for the electroless plating solution is not required, and it is environmentally friendly. In addition, since the copper film is formed on the surface of the nickel film, when the copper layer is formed on the surface of the circuit forming portion by the electroplating method, the nickel film protected by the copper film may dissolve into the electrolyte. Can be prevented, and contamination of the electrolytic solution can be prevented.

According to the third aspect of the present invention, there is provided the first aspect.
Alternatively, in the invention according to claim 2, the surface of the insulating substrate is roughened.

In such a method of manufacturing a circuit board, since the surface of the insulating substrate is roughened, the degree of adhesion between the insulating substrate and the nickel film is improved.

According to the invention described in claim 4, in claim 3,
In the invention described, the insulating substrate is formed from a material having a filler material inside the base material, and the surface of the insulating substrate is roughened by removing the base material until the filler material is exposed. I have.

In such a method of manufacturing a circuit board, the surface of the insulating substrate is easily roughened by removing the base material until the filler material inside the base material is exposed.

According to the fifth aspect of the present invention, the third aspect of the present invention is provided.
In the invention described, the insulating substrate is formed of a material having a filler material inside the base material, and after removing the base material until the filler material is exposed, the exposed filler material is removed to remove the exposed filler material in such a manner. In such a method for manufacturing a circuit board, the surface of the insulating substrate is easily roughened by removing the base material until the filler material inside the base material is exposed and then removing the exposed filler material.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a circuit board according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a method of manufacturing a circuit board different from that of the embodiment of the present invention, and (a) to (h) are longitudinal sectional views showing the circuit board in each step.

As shown in FIG. 1, in the method for manufacturing a circuit board, a nickel film 2 is formed on a surface of an insulating substrate 1 by a dry plating method, and the nickel film 2 is irradiated with an electromagnetic wave 11 to form a circuit contour portion 10. By removing, the circuit forming portion 8 and the circuit non-forming portion 9 are separately formed, a nickel thick film 3 is formed on the surface of the circuit forming portion 8 by electroplating, and the circuit non-forming portion 9 is etched. A circuit board is formed by forming a copper layer 4 on the surface of the film 3 by electroplating.

The insulating substrate 1 is formed of an electrically insulating material such as liquid crystal polymer, polyimide, ABS, polyetherimide, alumina ceramics, etc., and is formed in a planar shape or a three-dimensional shape. Can be used, and the case using the insulating substrate 1 made of a liquid crystal polymer will be described below.

First, as shown in FIG. 2A, the surface of the insulating substrate 1 is modified and cleaned by subjecting the insulating substrate 1 to alkaline degreasing and plasma treatment in the same manner as in the circuit board manufacturing method described above. Do.

Next, as shown in FIG. 2B, a nickel film 2 is formed on the surface of the insulating substrate 1 subjected to the plasma treatment by dry plating. The dry plating method is not particularly limited, and may be appropriately selected from vapor deposition, sputtering, ion plating, and the like. The film thickness is 200-400n
m is preferable.

Next, as shown in (c), the nickel film 2 is irradiated with an electromagnetic wave 11 to remove the circuit contour portion 10, thereby forming the circuit forming portion 8 and the circuit non-forming portion 9 separately. As the electromagnetic wave 11, X-rays, ultraviolet rays, or the like can be used in addition to a laser. However, since a laser is the most preferable, an electromagnetic wave 11 using a laser will be mainly described below. As the laser, for example, a second harmonic YAG laser (wavelength: 532 nm) is used, and the laser is irradiated while being moved to the surface of the insulating substrate 1 by operating with a galvanomirror or the like. The laser irradiation is performed in a portion of the surface of the insulating substrate 1 other than the circuit forming portion 8 where a circuit is formed, that is, in a circuit non-forming portion 9 which is an insulating space between circuit portions. By irradiating at least a boundary region between the circuit non-forming portion 9 and the circuit forming portion 8 while moving the laser along the pattern of the circuit non-forming portion 9, the boundary between the circuit non-forming portion 9 and the circuit forming portion 8 is irradiated. This is to remove the nickel film 2 in the region. Therefore, of the nickel film 2 of the circuit non-forming portion 9, the nickel film 2 at the boundary with the circuit forming portion 8 is removed, and the laser non-irradiated portion remains without being removed together with the nickel film 2 of the circuit forming portion 8. Will be. Laser irradiation energy is, for example, 10 to 300 μj.
/ Pulse is preferable, and the surface of the insulating substrate 1 together with the nickel film 2 may be removed at the same time.

Next, as shown in FIG. 1D, a nickel layer is formed on the surface of the nickel film 2 of the circuit forming portion 8 to a thickness of about 5 to 10 μm by an electroplating method in which the insulating substrate 1 is immersed in an electrolytic solution. At this time, since the boundary between the circuit forming portion 8 and the circuit non-forming portion 9 has been removed by laser irradiation, only the circuit forming portion 8 of the circuit forming portion 8 and the circuit non-forming portion 9 is supplied from an external power supply. If a current is supplied, the nickel layer is electroplated on the circuit forming portion 8, but the nickel layer is not electroplated on the surface of the nickel film 2 in the circuit non-forming portion 9.

Next, as shown in FIG. 1E, the insulating substrate 1 is immersed in a nitric acid solution having a concentration of about 20% to etch the nickel film 2 in the circuit non-formed portion 9. At this time, care is taken so that the nickel layer of the circuit forming portion 8 is not excessively etched.

Next, as shown in (f), a copper layer 4 is formed on the surface of the nickel layer of the circuit forming portion 8 to a thickness of about 15 μm by an electroplating method in which the insulating substrate 1 is immersed in an electrolytic solution. At this time, the circuit non-forming portion 9 is formed by the above-described etching process.
Since the nickel film 2 is removed, only the circuit forming portion 8 of the circuit forming portion 8 and the circuit non-forming portion 9 is electroplated with the copper layer 4. Further, since the nickel film 2 in the circuit non-forming portion 9 has been removed, nickel of the nickel film 2 does not melt in the electrolytic solution.

Next, as shown in (g) to (h), after the copper layer 4 is plated on the nickel layer to form a circuit, nickel plating and gold plating are performed, if necessary, respectively. By applying about 4 to 4 μm, the circuit board can be finished.

In such a method of manufacturing a circuit board, since the copper layer 4 is formed on the surface of the circuit forming portion 8 by electroplating, there is no need to perform electroless plating. Therefore, wastewater and wastewater treatment equipment for the electroless plating solution is not required, and it is environmentally friendly. Also, since the nickel thick film 3 is formed on the surface of the circuit forming portion 8 by electroplating and the circuit non-forming portion 9 is etched, the nickel film 2 in the circuit non-forming portion 9 is removed and the nickel thick film 3 is removed. When the copper film 7 is formed on the surface of the film by electroplating, the nickel of the nickel film 2 can be prevented from being dissolved in the electrolytic solution, and contamination of the electrolytic solution can be prevented. Therefore, the nickel dissolved in the electrolytic solution does not mix into the copper layer 4 to form irregularities on the surface of the copper layer 4. For example, when nickel plating or gold plating is performed on the copper layer 4 later, the surface of the gold plating And the bondability of a bonding wire such as when wire bonding is performed on a gold plating surface can be improved. Also,
Since the electromagnetic wave 11 is applied to the nickel film 2 formed on the surface of the insulating substrate 1 by the dry plating method to remove the circuit contour portion 10, the circuit forming portion 8 and the circuit non-forming portion 9 are formed separately. In addition, there is no need to perform a complicated etching process using, and it is not necessary to irradiate the entire surface of the circuit non-forming portion 9 with the electromagnetic wave 11, and the circuit forming portion 8 can be formed. Further, since the circuit forming portion 8 is formed on the insulating substrate 1 via the nickel film 2, the adhesion strength between the insulating substrate 1 and the circuit forming portion 8 is improved.

FIGS. 2A to 2H show a method of manufacturing a circuit board different from the above embodiment of the present invention. FIGS. 2A to 2H are longitudinal sectional views showing the circuit board in each step. Also, FIG.
It is a longitudinal section of an insulating board used for this circuit board manufacturing method, and shows three kinds of different insulating boards in (a)-(c).

As shown in FIGS. 2 and 3, the method of manufacturing the circuit board is the same as the method of manufacturing the circuit board shown above. The difference is that the surface of the insulating substrate 1 is roughened. Here, only the surface roughening treatment of the surface of the insulating substrate 1 will be described below, and other steps are the same as those of the circuit board manufacturing method described above, and the description thereof will be omitted.

This surface roughening can be performed between the alkaline degreasing of the insulating substrate 1 and the plasma treatment in the method for manufacturing a circuit board shown in the above, and the surface of the insulating substrate 1 is made of sodium hydroxide, chromic acid solution. , A KOH aqueous solution, a phosphoric acid solution or the like can give fine irregularities. Here, a base material 1a having a large number of filler materials 1b therein.
And a liquid crystal polymer comprising a skin layer 1c having no filler material 1b on the surface is used as the insulating substrate 1, and FIG.
(C) illustrates three types of roughened states. In (a), the surface of the insulating substrate 1 is roughened by the surface treatment of the skin layer 1c on the surface of the insulating substrate 1. In (b), the surface of the insulating substrate 1 is roughened by removing the base material 1a until the filler material 1b inside the base material 1a is exposed. In (c), after removing the base material 1a until the filler material 1b is exposed, the exposed filler material 1b is removed.
Is removed to make the surface of the insulating substrate 1 rough. The difference between the three types of roughened states (a) to (c) can be changed depending on the type of the liquid for performing the surface treatment, the treatment temperature, the treatment time, and the like. For example, when using sodium hydroxide, the surface treatment is performed under the conditions of a concentration of 500 g / l, a temperature of 80 ° C., and a time of about 20 minutes.
(A) The surface treatment of the skin layer 1c can be performed.

FIGS. 4A to 4G show a method of manufacturing a circuit board different from the above embodiment of the present invention. FIGS. 4A to 4G are longitudinal sectional views showing the circuit board in each step.

As shown in FIG. 4, in the method of manufacturing the circuit board, a nickel film 2 is formed on the surface of an insulating substrate 1 by dry plating, and a copper film 7 is formed on the surface of the nickel film 2. 2 and the copper film 7 are irradiated with an electromagnetic wave 11 to remove the circuit contour portion 10 so that the circuit forming portion 8 and the circuit non-forming portion 9 are separately formed, and a copper layer is formed on the surface of the circuit forming portion 8 by electroplating. 4 to form a circuit board.

As the insulating substrate 1, a substrate similar to the method for manufacturing a circuit board shown above can be used.

First, as shown in (a), the insulating substrate 1 is degreased with an alkali to wash and remove oil and the like adhering to the surface. Next, the insulating substrate 1 is placed in a vacuum chamber (not shown), and the surface of the insulating substrate 1 is modified and cleaned by plasma treatment to improve the adhesion strength of the surface of the insulating substrate 1.

Next, as shown in (b) to (c), a nickel film 2 is formed on the surface of the plasma-treated insulating substrate 1 by dry plating, and a copper film 7 is formed on the surface of the nickel film 2. . The dry plating method is not particularly limited, and may be appropriately selected from vapor deposition, sputtering, ion plating, and the like. The thickness of the nickel film 2 is 1 to 1
Preferably, the thickness of the copper film 7 is 20 to 500 nm, and particularly preferably, the thickness of the nickel film 2 is 2 to 10 nm.
The copper film 7 has a thickness of 250 to 350 nm.

Next, as shown in (d), the nickel film 2 and the copper film 7 are irradiated with electromagnetic waves 11 to remove the circuit contour portion 10 to separate the circuit forming portion 8 from the circuit non-forming portion 9. Form. As the electromagnetic wave 11, in addition to the laser, X
Although a line, an ultraviolet ray, or the like can be used, a laser is most preferable. Therefore, a description will be mainly given of a case where a laser is used as the electromagnetic wave 11 hereinafter. As the laser, for example, a second harmonic YAG laser (wavelength: 532 nm) is used, and the laser is irradiated while being moved to the surface of the insulating substrate 1 by operating with a galvanomirror or the like. The laser irradiation is performed in a portion of the surface of the insulating substrate 1 other than the circuit forming portion 8 where a circuit is formed, that is, in a circuit non-forming portion 9 which is an insulating space between circuit portions. The circuit non-forming portion 9 is provided at least in a boundary region between the circuit non-forming portion 9 and the circuit forming portion 8.
By irradiating the laser while moving it along the pattern described above, the nickel film 2 and the copper film 7 in the boundary region between the circuit non-forming portion 9 and the circuit forming portion 8 are removed.
Therefore, of the nickel film 2 and the copper film 7 of the circuit non-forming portion 9, the nickel film 2 and the copper film 7 at the boundary with the circuit forming portion 8 are removed, and the laser non-irradiated portion becomes the nickel film of the circuit forming portion 8. It is left without being removed together with the film 2 and the copper film 7. The irradiation energy of the laser is, for example, 10 to 30.
It is preferably about 0 μj / pulse, and the surface of the insulating substrate 1 may be removed simultaneously with the nickel film 2 and the copper film 7.

Next, as shown in (e), a copper layer 4 is formed on the surface of the copper film 7 of the circuit forming portion 8 to a thickness of about 15 μm by an electroplating method in which the insulating substrate 1 is immersed in an electrolytic solution. At this time, since the boundary between the circuit forming portion 8 and the circuit non-forming portion 9 has been removed by laser irradiation, only the circuit forming portion 8 of the circuit forming portion 8 and the circuit non-forming portion 9 is supplied from an external power supply. If the current is supplied, the copper layer 4
Is electroplated, but the copper layer 4 is not electroplated on the surface of the copper film 7 in the circuit non-formed portion 9.

Next, as shown in (f) to (g), after forming the circuit by plating the copper layer 4 on the copper film 7 in this manner, nickel plating and gold plating are respectively performed as necessary. The circuit board can be finished by applying about 0.4 to 4 μm.

In such a method of manufacturing a circuit board, since the copper layer 4 is formed on the surface of the circuit forming portion 8 by electroplating, there is no need to perform electroless plating. Therefore, wastewater and wastewater treatment equipment for the electroless plating solution is not required, and it is environmentally friendly. Further, since the copper film 7 is formed on the surface of the nickel film 2, when the copper layer 4 is formed on the surface of the circuit forming portion 8 by the electroplating method, the nickel of the nickel film 2 protected by the copper film 7 is formed. Can be prevented from being dissolved in the electrolytic solution, and contamination of the electrolytic solution can be prevented. Therefore, the nickel dissolved in the electrolytic solution does not mix into the copper layer 4 to form irregularities on the surface of the copper layer 4. For example, when nickel plating or gold plating is performed on the copper layer 4 later, the surface of the gold plating And the bondability of a bonding wire such as when wire bonding is performed on a gold plating surface can be improved. The nickel film 2 formed on the surface of the insulating substrate 1 by dry plating and the copper film 7
Since the circuit forming section 8 and the circuit non-forming section 9 are separately formed by irradiating the circuit contour section 10, it is not necessary to perform a complicated etching process using a resist, and the circuit non-forming section is not required. It is not necessary to irradiate the entire surface of 9 with the electromagnetic wave 11, and the circuit forming portion 8 can be formed. Further, since the copper film 7 is formed on the insulating substrate 1 with the nickel film 2 interposed therebetween, the adhesion strength between the insulating substrate 1 and the circuit forming portion 8 is improved.

When a liquid crystal polymer or the like is used as the insulating substrate 1, it is also preferable to roughen the surface of the insulating substrate 1 as in the above-described method for manufacturing a circuit board.

[0041]

According to the first aspect of the present invention, since the copper layer is formed on the surface of the circuit forming portion by the electroplating method, there is no need to perform electroless plating. Therefore, wastewater and wastewater treatment equipment for the electroless plating solution is not required, and it is environmentally friendly. In addition, since the copper film is formed on the surface of the nickel film, when the copper layer is formed on the surface of the circuit forming portion by electroplating, the nickel of the nickel film protected by the copper film dissolves in the electrolytic solution. Soaking can be prevented, and contamination of the electrolytic solution can be prevented.

In the second aspect of the present invention, since the copper layer is formed on the surface of the circuit forming portion by the electroplating method, there is no need to perform electroless plating. Therefore, wastewater and wastewater treatment equipment for the electroless plating solution is not required, and it is environmentally friendly. Also, since a nickel thick film is formed on the surface of the circuit forming portion by electroplating and the non-circuit forming portion is etched, the nickel film on the circuit non-forming portion is removed, and the surface of the nickel thick film is plated by electroplating. Thus, when a copper film is formed, the nickel of the nickel film can be prevented from being dissolved in the electrolytic solution, and contamination of the electrolytic solution can be prevented.

According to the third aspect of the present invention, since the surface of the insulating substrate is roughened, the degree of adhesion between the insulating substrate and the nickel film is improved.

According to the fourth aspect of the present invention, the surface of the insulating substrate is easily roughened by removing the base material until the filler material inside the base material is exposed.

According to the fifth aspect of the present invention, the surface of the insulating substrate can be easily roughened by removing the base material until the filler material inside the base material is exposed, and then removing the exposed filler material. I have.

[Brief description of the drawings]

FIG. 1 shows a method for manufacturing a circuit board according to an embodiment of the present invention, and (a) to (h) are longitudinal sectional views showing the circuit board in each step.

FIGS. 2A to 2H are longitudinal sectional views showing a circuit board in respective steps, showing a method of manufacturing a circuit board different from that of the embodiment of the present invention. FIGS.

FIG. 3 is a longitudinal sectional view of an insulating substrate used in the method for manufacturing a circuit board according to the embodiment of the present invention, and (a) to (c) show three different types of insulating substrates.

FIG. 4 shows a method of manufacturing a circuit board different from the above according to the embodiment of the present invention, and (a) to (h) are longitudinal sectional views showing the circuit board in each step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating substrate 1a Base material 1b Filler material 1c Skin layer 2 Nickel film 3 Nickel thick film 4 Copper layer 5 Nickel plating layer 6 Gold layer 7 Copper film 8 Circuit forming part 9 Circuit non-forming part 10 Circuit contour part 11 Electromagnetic wave

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shiro Sakamoto 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd. Terms (reference) 5E339 BC01 BC02 BD03 BD05 BE05 BE11 DD03 DD04 DD10 5E343 AA02 AA12 AA22 AA36 AA38 BB17 BB24 BB44 BB71 DD22 DD43 DD75 EE08 EE32 ER23 ER26 GG04 GG20

Claims (5)

[Claims] A nickel film is formed on a surface of an insulating substrate by dry plating, and a circuit forming portion and a non-circuit forming portion are separately formed by irradiating the nickel film with an electromagnetic wave to remove a circuit contour portion; After forming a nickel thick film on the surface of the formed portion by electroplating and etching the non-circuit-formed portion, a copper layer is formed on the surface of the nickel thick film by electroplating to form a circuit board. Manufacturing method of a circuit board. 2. A circuit by forming a nickel film on a surface of an insulating substrate by a dry plating method and a copper film on a surface of the nickel film, and irradiating the nickel film and the copper film with an electromagnetic wave to remove a circuit contour portion. A method of manufacturing a circuit board, comprising: forming a formed portion and a circuit non-formed portion separately; forming a copper layer on the surface of the circuit formed portion by electroplating to form a circuit board. 3. The method according to claim 1, wherein the surface of the insulating substrate is roughened. 4. The insulating substrate according to claim 1, wherein the insulating substrate is formed of a material having a filler material inside the base material, and the surface of the insulating substrate is roughened by removing the base material until the filler material is exposed. 4. The method for manufacturing a circuit board according to 3. 5. An insulating substrate is formed from a material having a filler material inside a base material. After removing the base material until the filler material is exposed, the exposed filler material is removed to make the surface of the insulating substrate rough. 4. The method for manufacturing a circuit board according to claim 3, wherein: