JP2003008174A - Wiring board manufacturing method - Google Patents

Abstract

(57) [Summary] [Problem] It is difficult to generate an insulating layer residue. There has been a demand for a method of manufacturing a wiring board in which the reliability of conduction is improved by making this less likely to occur, and a via conduction failure does not occur. Moreover, even when the insulating layer is polyimide,
There has been a demand for a method of manufacturing a wiring board in which the visibility of polyimide residues is improved by inspection of vias after laser processing. Using a material in which a copper layer serving as the bottom of a conductive via is formed on one surface of an insulating layer, laser processing is performed from the insulating layer side so as to reach the copper layer, and the processed holes are formed. In the method of manufacturing a wiring board that conducts conduction inside, a coloring treatment is performed on at least the bottom portion of the conductive via on the surface of the copper layer that contacts the insulating layer before laser processing. A method for manufacturing a wiring board is provided.

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 wiring board typified by a film carrier or a printed wiring board, and more particularly, it has wiring circuits on both sides of an insulating layer and conducts the wiring circuits on both sides by conducting vias. The present invention relates to a method of manufacturing a wiring board.

[0002]

2. Description of the Related Art Conventionally, when a conductive via is formed by using a laser, the energy density is lowered to the energy for processing the copper foil in the via forming portion and then the insulating layer with the energy for processing the copper foil. Process polyimide. The wiring board is manufactured by processing the copper foil until it reaches the copper foil on the back surface, laser processing the via portion, and conducting the inside of the processed hole.

In particular, since the UV-YAG laser is a pulse laser, it has a characteristic that a workpiece can be gradually processed depending on the number of shots. Therefore, if the number of laser shots is insufficient, processing residues will occur. (See FIGS. 5 and 6)

[0004]

Conventionally, when manufacturing a printed circuit board having wiring patterns on both sides, UV-
When the via portion is processed by the YAG laser processing, a residue of the insulating layer may be generated at the bottom portion of the via and the conduction of the via may be insufficient. As a result, the reliability of conduction is lowered, and it also causes a failure in conduction of the via.

Further, when the insulating layer is polyimide, the visibility of the polyimide residue is poor in the inspection of the via after laser processing, and the inspection is difficult.

Therefore, when manufacturing a printed circuit board having wiring patterns on both sides, when the via portion is processed by UV-YAG laser processing, residues of the insulating layer are less likely to occur at the bottom of the via. There is a demand for a method for manufacturing a wiring board in which the reliability of conduction is improved by making this less likely to occur and a conduction failure of vias does not occur.

Further, even when the insulating layer is made of polyimide, there is a demand for a method of manufacturing a wiring board in which the visibility of polyimide residue is improved by inspection of vias after laser processing.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 uses a material in which a copper layer serving as a bottom portion of a conductive via is formed on one surface of an insulating layer, In the method of manufacturing a wiring board, in which laser processing is performed from the insulating layer side so as to reach the copper layer, and conduction processing is performed inside the processed hole, the surface of the copper layer that contacts the insulating layer before laser processing is performed. The present invention provides a method for manufacturing a wiring board, characterized in that at least a portion that becomes the bottom of the conductive via is subjected to coloring treatment.

As a result, since at least the bottom surface of the conductive via on the surface of the copper layer in contact with the insulating layer is colored, the reflectance changes when the laser processing reaches the copper layer, and the processing end point is reached. It becomes easier to detect, and by further processing from that point, it becomes possible to perform processing without residue.

The coloring process may be any color as long as it can be colored with a color capable of detecting the processing end point, and the color is not limited to black, and a color with which the processing end point can be detected. Any color may be used, for example, a method in which a colored conductive material such as a conductive adhesive is applied may be used, but an oxidation treatment is preferable.

This is because the adhesion between the copper layer and the insulating layer can be increased. Also as the oxidation treatment, copper oxide mainly composed of CuO (blackening treatment: Example 2) is particularly preferable. Copper oxide includes CuO and Cu ₂ O, but CuO
Has a black color, and it is easy to detect the end during laser processing.

Further, at least the portion which becomes the bottom of the conductive via may be processed. For example, in the case of an oxidation treatment, it is preferable that the whole is oxidized rather than being selectively processed. In addition, a copper layer may of course be formed on the other surface side.

In order to solve the above-mentioned problems, a copper layer is formed on the other surface of the insulating layer, and the copper layer on the other surface is opposite to the insulating layer. The present invention also provides a method for manufacturing a wiring board according to claim 1, characterized in that it is also colored.

As a result, if the copper layer on the other surface is colored on the surface opposite to the insulating layer, that is, the surface on which the laser irradiation is performed, whether the diameter of the via becomes a desired size after processing. This is preferable because it facilitates the inspection when such an inspection is performed.

However, even when the blackening treatment or the oxidation treatment is performed on only one side, there is an effect of clarifying which is the copper foil on the laser processing side, and therefore it can be appropriately selected depending on the case.

In this way, when the blackening treatment or the oxidation treatment is performed only on the insulating layer side of the copper foil opposite to the laser irradiation side,
When the laser processing is performed on the via part, the processing of the insulating layer is finished and the copper surface on the back side is also laser processed to remove the blackened or oxidized copper foil surface by laser processing and to reduce the reflectance of the copper foil. The change makes it possible to clarify the end point of the laser processing, thereby eliminating the processing residue of the insulating layer which is a problem.

In order to solve the above-mentioned problems, the invention according to claim 3 further includes, as the laser processing, processing for removing the colored portion after reaching the copper layer on the one surface. A method of manufacturing a wiring board according to claim 1 or claim 2 is provided.

This is because the colored portion becomes the bottom of the via, so it is preferable to remove it in the case of oxidation treatment, and it is necessary to remove it in the case of coloring treatment with an insulator. Is. Even in other cases, it is preferable to remove it when the electric resistance is different from that of the copper layer, or when the conduction process performed in the via is difficult to perform.

In order to solve the above-mentioned problems, the invention described in claim 4 uses a UV-YAG laser for the laser processing, and the wiring board according to any one of claims 1 to 3. A manufacturing method is provided.

Examples of lasers that can be used in the present invention include excimer lasers and carbon dioxide lasers. However, it is preferable to use the UV-YAG laser as in the fourth aspect of the present invention, since both the copper layer and the insulating layer can be easily processed. As a result, a copper layer exists on the irradiation surface side, and when the copper layer is processed, excellent workability is exhibited.

In order to solve the above problems, the invention according to claim 5 is characterized in that the coloring treatment is an oxidation treatment, and the method for manufacturing a wiring board according to any one of claims 1 to 4. Is provided. This is because a thin colored layer can be easily processed, and even if an oxide film remains in a portion other than the processed portion, there is no particular adverse effect on the use of the wiring board. Particularly, it is preferable to form an oxide film mainly composed of CuO.

[0022]

1 and 2 show a method of manufacturing a wiring board.
Use to explain. A copper foil 10 that has not been treated with polyimide for the insulator 11 and a copper foil 20 that has been blackened on the front and back are bonded together with a thermoplastic adhesive. UV-YAG laser processing is performed using this material.

As the conditions for laser processing, for example, copper foil is processed at 0.2 J per pulse. The number of shots depends on the equipment used, but with a copper foil of 12 μm, the processing of the copper foil is completed in about 2 to 15 shots.
A form like 0b is obtained. When processing the polyimide next, the processing energy of the laser is dropped to 0.02 J per pulse before use. 20 to 30
The shot makes it possible to process only the polyimide and complete the process with the copper foil on the back surface.

The number of shots required is about 30 to 50 in the case of 50 μm polyimide. Since the etching rate that can be processed is different depending on the material of the polyimide, if the material of the polyimide is different, the condition of the shot number is necessary. When processing of polyimide is over,
A form such as 1c is obtained.

When the processing of the polyimide is completed, the blackened surface of the copper foil 20 on the rear surface remains in the state shown in FIG. 2 (a). In this state, whether or not there is a processing residue of polyimide is unknown. Further, the processing energy of the laser is returned to 0.2 J per pulse and the backside copper foil is processed for 1 or 2 shots, whereby the blackening treatment film is removed and the copper foil 20a can be obtained. If the copper foil in this state is obtained, it is clear that there is no polyimide residue, and the reliability of the via is improved.

After that, a plating process is performed, and a conduction process for conducting the front and back sides is performed to perform a method for manufacturing a wiring board.
In this process, if there was a processing residue in the via, plating was not applied to the part where the residue remained, which was the cause of poor conduction, but the residue did not adhere, or it was easy to find it, and conduction was made in advance. Since conduction failure after processing can be predicted, stable conduction processing is possible.

[0027]

EXAMPLE 1 Example 1 will be described in detail below with reference to FIGS. 1 and 2. For 9 μm copper foil 10,
Blackening solution (sodium hypochlorite 40g / l, sodium hydroxide 20g / l, trisodium phosphate 20g /
l, liquid temperature 90 ° C., dipping treatment for 5 minutes), blackened both surfaces, and polyimide thermoplastic adhesive (polyimide thermoplastic adhesive manufactured by DuPont) on 30 μm polyimide 11 1
9 μm copper foil 20 is adhered with 0 μm sandwiched on both sides. As a result, a double-sided copper foil substrate as shown in FIG. 1 (a) can be formed.

Then, a UV-YAG laser beam machine (LAVIA UV 2000 manufactured by Sumitomo Heavy Industries, Ltd.) is used to irradiate the via formation portion with a beam having a diameter of 60 μm.
The copper foil 10 can be removed in a state as shown in FIG. 1C by irradiating 6 shots with energy of 0.2 J per pulse in order to process the copper foil 10. It should be noted that the state shown in FIG. 1B is obtained with a few shots.

Next, in order to process the polyimide 11, the laser was set to 0.2 J per pulse for 3
By irradiating 0 shots, the form of FIG. 1 (f) is obtained. When the number of shots is small, the states shown in FIGS. 1D and 1E are obtained.

When the processing of the polyimide is completed, the copper foil will be in the state as shown in FIG. In this state, unprocessed polyimide may remain on the copper foil surface, resulting in poor connection of vias. Therefore, the energy density of the laser is returned to 0.2 J per pulse of copper foil processing. Further irradiation with 1 or 2 shots removes the blackened surface of the copper foil as shown in FIG. 1 (g), and it can be confirmed that there is no residue of polyimide. In addition, as shown in FIG. 2, by irradiating the blackened surface with a laser, the conductor layer 20a shown in FIG. 2C is formed, and a processed portion having no polyimide residue is obtained.

By using the laser processing method of the present invention, it is possible to form a via without a processing residue, and it is possible to perform laser processing in which the presence or absence of a residue is clear. After that, the vias are treated with a plating solution (direct plating process manufactured by Meltex Co., Ltd.), a plating treatment for forming a thickness of 10 μm is performed, a conduction treatment for conducting the front and back sides is performed, and a wiring board manufacturing method is performed. Since there was no residue, the conduction treatment could be completed completely.

(Embodiment 2) Hereinafter, an embodiment will be described in detail with reference to FIG. A 12 μm copper foil 10 was pasted with polyimide using a blackening treatment solution (sodium hypochlorite 40 g / l, sodium hydroxide 20 g / l, trisodium phosphate 20 g / l, solution temperature 90 ° C., 5 minutes dip treatment). The surface to be applied is blackened, and 10 μm of the same polyimide-based thermoplastic adhesive as in Example 1 is sandwiched between both sides of the polyimide 11 of 30 μm to adhere the copper foil 20 of 12 μm. As a result, a double-sided copper foil substrate as shown in FIG. 1 (a) can be formed.

Next, a UV-YAG laser beam machine is used to irradiate the via formation portion with a beam having a diameter of 50 μm. By irradiating 10 shots with energy having an energy density of 20 J / cm ² to process the copper foil 10, the copper foil 10 can be removed in the state as shown in FIG. 3C. (The state of FIG. 3B for a few shots) Next, the laser energy density is 0.02 J per pulse for processing the polyimide 11.
And irradiation for 30 shots gives the form of FIG. 3 (f). (When the number of shots is small,
The state of (e) is obtained. )

When the processing of the polyimide is completed, the copper foil will be in a state as shown in FIG. In this state, unprocessed polyimide may be left on the copper foil surface, resulting in poor connection of vias. Therefore, the energy density of the laser is further reduced to 0.2 J per pulse of copper foil processing, and then 1 After 2 shots of irradiation, the blackened surface of the copper foil is removed as shown in FIG. 3 (g), and it can be confirmed that there is no polyimide residue. Further, as shown in FIG. 2, by irradiating the blackened surface with a laser, a state as shown by 20a in FIG. 2C is obtained, and a processed portion having no polyimide residue is obtained.

By using the laser processing method of the present invention, it is possible to form a via without a processing residue as in the case of claim 1, and it is possible to perform laser processing in which the presence or absence of a residue is clear.
After that, the same plating treatment as in Example 1 was performed, a conduction treatment for conducting the front and back sides was performed, and a method for manufacturing a wiring board was performed. As a result, there was no residue, so that the conduction treatment was completed.

(Embodiment 3) Hereinafter, an embodiment will be described in detail with reference to FIG. 12 μm copper foil on copper foil 40 and 20
And oxidize them (bake in air at 250 ° C. for 20 minutes). Next, the same polyimide as in Example 1 and a thermoplastic adhesive of 10 μm are sandwiched on both sides and bonded to a copper foil. As a result, a double-sided copper foil substrate as shown in FIG. 1 (a) can be formed.

Next, a UV-YAG laser beam machine is used to irradiate the via formation portion with a beam having a diameter of 60 μm. By irradiating 10 shots with an energy density of 0.2 J per pulse in order to process the copper foil 40, FIG.
The copper foil 40 can be removed in the state as shown in (c). In addition,
With a few shots, the state shown in FIG.

Next, in order to process the polyimide 11, the energy density of the laser is set to 0.02 J per pulse and irradiation is performed for 30 shots to obtain the form of FIG. 4 (f). When the number of shots is small, the states shown in FIGS.

In this state, unprocessed polyimide may remain on the surface of the copper foil, resulting in poor connection of vias. Therefore, the energy density of the laser is further returned to 0.2 J per pulse of the copper foil processing. After irradiating 1 or 2 more shots, the oxidized surface of the copper foil is removed as shown in Fig. 4 (g), and the dull copper foil returns to the gloss of the conventional copper foil by the oxidation treatment, and the polyimide residue is surely left. It can be confirmed that there is not.

By oxidizing the copper foil 40, the contrast of the glossiness between the copper foil 20a and the copper foil 40 in the laser-processed portion becomes large, and it becomes easier to confirm when checking with an inspection machine.

By using the laser processing method of the present invention, it is possible to form a via without a processing residue as in the first aspect, and it is possible to perform laser processing in which the presence or absence of a residue is clear.

After that, the same plating treatment as in Example 1 was performed, and a conduction treatment for conducting the front and back sides was performed. As a result of carrying out the method for manufacturing the wiring board, there was no residue, so that the conduction treatment could be completely performed. It was

[0043]

By using the method for manufacturing a wiring board according to the present invention, it is possible to perform processing without a residue of laser processing, and it is possible to easily inspect a processed portion. Further, in the step of oxidizing the copper foil, the copper foil can be attached without worrying about the atmosphere at the time of attaching the copper foil at a high temperature as in the past, so that the cost advantage is large.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing the embodiment of FIG.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the present invention different from the embodiment shown in FIG.

FIG. 4 is a schematic cross-sectional view showing an embodiment of the present invention different from the embodiments of FIGS. 1 and 2.

FIG. 5 is a schematic cross-sectional view showing a conventional example.

FIG. 6 is a schematic perspective view showing a conventional example.

[Explanation of symbols]

10 ... Conductor layer 10a ... Conductor layer after laser processing 10b ... Conductor layer after laser processing 11 ... Insulating layer 11a..Insulation layer after laser processing 11b..Insulation layer after laser processing 11c..Insulation layer after laser processing 12 ... Conductor layer 20 ... Conductor layer after blackening or oxidation treatment 20a ... Laser processed conductor layer 30 ... Conductor layer after blackening or oxidation on one side 30a ... Conductor layer after laser processing 40 ... Conductor layer after blackening or oxidation treatment 40a ... Conductor layer after laser processing 40b ··· Conductor layer after laser processing

Claims (5)

[Claims] 1. A hole processed by laser processing from the insulating layer side so as to reach the copper layer by using a material in which a copper layer which is a bottom of a conductive via is formed on one surface of the insulating layer. In the method for manufacturing a wiring board in which the inside of the copper layer is subjected to a conduction treatment, it is preferable to perform a coloring treatment on at least a bottom portion of the conduction via of a surface of the copper layer in contact with the insulating layer before performing the laser processing. A method for manufacturing a characteristic wiring board. 2. A copper layer is also formed on the other surface of the insulating layer, and the copper layer on the other surface is also colored on the surface opposite to the insulating layer. The method for manufacturing a wiring board according to claim 1. 3. The wiring board according to claim 1, further comprising, as the laser processing, processing for removing a colored portion after reaching the copper layer on the one surface. Manufacturing method. 4. The method of manufacturing a wiring board according to claim 1, wherein a UV-YAG laser is used for the laser processing. 5. The method of manufacturing a wiring board according to claim 1, wherein the coloring treatment is an oxidation treatment.