JP2003060331A - Method of manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a printed wiring board, which can remove oxidized film on a circuit pattern exposed to the surface of a high-density product and which is superior in conductive paste printing, metal plating and electric connection reliability after soldering mounting. SOLUTION: In a process ((d) in Figure 1) performing soft etching by etching liquid constituted of oxoacid and oxidizing agent, preprocessing ((c) in Figure 1) is previously performed by aqueous solution constituted of organic compound soluble to water, prior to soft etching. Thus, the wettability of etching liquid with respect to the circuit pattern is improved.

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 printed wiring board widely used in various electronic devices such as personal computers, mobile communication telephones, video cameras and the like.

[0002]

2. Description of the Related Art In recent years, as electronic devices such as personal computers, word processors, video-integrated cameras and mobile phones have become more sophisticated and have higher densities, electronic parts have tended to become smaller, highly integrated, and have more pins. is there.

For this reason, the form of the printed wiring board is becoming more and more low in permittivity, thin, and lightweight, and the mounting density is increased, and a uniform surface treatment technique is established for a high-density mounting land. Is being requested.

A conventional method for manufacturing a printed wiring board will be described below.

FIG. 3 is a flowchart of a conventional method for manufacturing a printed wiring board.

A circuit pattern is formed on the copper foil layer or the copper plating layer on the front and back of the base material by means of etching or the like (FIG. 3 (a)), and then the printed wiring board on which this circuit pattern is formed. Then, a solder resist is formed by means of exposure, development, etc. (FIG. 3B). This solder resist is selectively formed in a required portion, and a portion of the circuit pattern that is not used for electrical connection with the outside is generally covered with the solder resist. After that, the exposed portion of the circuit pattern is contacted with a metal pin in order to confirm the continuity of the circuit pattern, and an electrical inspection (FIG. 3D) is performed. Formation of anti-corrosion film for soldering mounting of chip parts (Fig. 3 (e
1)) or other surface treatment, or metal plating (Fig. 3 (e2)) or conductive paste printing (Fig. 3 (e3)) is performed according to the purpose of use, and a final visual inspection is performed. (FIG.3 (f)) is performed.

Here, in general, when performing an electrical inspection and various surface treatments, in order to obtain an electrical connection with a circuit pattern, soft etching is performed with a liquid containing an oxo acid and an oxidizing agent before the electrical inspection and various surface treatments. Processing (Fig. 3 (c
The oxide film on the surface of the circuit pattern is removed in advance by performing 1)) or performing a derusting treatment (FIG. 3 (c2)) with a solution containing oxo acid. For a product having a conventional packaging density, the soft etching or derusting treatment here has achieved a desired state by simply spraying the treatment liquid on the product or immersing the product in the treatment liquid.

[0008]

However, in the above-mentioned conventional method, when a high-density product in recent years is processed, the solder resist has a hydrophobic property, so that the solder resist layer is partially removed. The circuit pattern exposed on the surface repels the processing liquid on the circuit pattern due to the hydrophobic solder resist formed around or in the vicinity of the circuit pattern, so bubbles are generated and remain attached on the circuit pattern during liquid processing. There is a phenomenon that it is not removed and normal processing is not performed. At this time, the oxide film remains on the surface of the circuit pattern that has not been normally processed, and as a result, conductive paste printing, metal plating, soldering mounting, and electrical inspection are performed on this circuit pattern. In that case, there is a problem in that these conductive layers are not normally formed or electrical connection is not normally obtained.

The present invention solves the above-mentioned conventional problems, and can remove an oxide film on a circuit pattern exposed on the surface of a high-density product, and print conductive paste, metal plating, after soldering and after electrical mounting. It is an object of the present invention to provide a method for manufacturing a printed wiring board having excellent electrical connection reliability during inspection.

[0010]

In order to achieve the above object, the invention according to claim 1 of the present invention, in particular, is an aqueous solution containing an organic compound which is previously soluble in water before the soft etching treatment. Is a method for manufacturing a printed wiring board, which is characterized by performing pretreatment with a pretreatment liquid that comprises a solder resist and an organic compound by utilizing the lipophilicity that the solder resist originally has. Since good wettability can be obtained with the pretreatment liquid, there is no phenomenon that bubbles adhere to the pretreatment liquid and the circuit pattern where the solder resist is formed on or around the periphery of the pretreatment liquid. Wettability is obtained. By performing the next soft etching treatment while maintaining the wettability obtained here, the wettability between the etching solution and the circuit pattern is also ensured, so that the oxide film on the circuit pattern surface can be reliably removed. It has the effect of being able to.

The invention according to claim 2 is characterized in that the water-soluble organic compound used in the pretreatment liquid is an additive contained in the etching liquid.
In the method for manufacturing a printed wiring board according to the description, by using an organic compound contained in the etching solution as an additive in the pretreatment liquid, good wettability is obtained between the solder resist and the pretreatment liquid containing the organic compound. There is no phenomenon of bubbles adhering between the pretreatment liquid and the circuit pattern where the solder resist is formed on or around the periphery, and good wettability is obtained. Here, by performing the next soft etching treatment while maintaining the wettability, the wettability between the etching solution and the circuit pattern is also ensured, so that the oxide film on the circuit pattern surface can be surely removed. Have an effect. Further, even if the pretreatment liquid remaining on the surface of the printed wiring board after the pretreatment is mixed in the etching liquid used for the next soft etching treatment, this pretreatment liquid is a substance originally contained as an additive to the etching liquid. Therefore, the etching power can be maintained without changing the composition of the etching solution.

According to the third aspect of the present invention, in particular, the additive concentration of the pretreatment liquid is 0.5 times to 2 times the concentration in the etching liquid.
The method for manufacturing a printed wiring board according to claim 2, wherein the concentration is doubled. Here, since the additive concentration of the pretreatment liquid is set to a value close to the additive concentration of the etching liquid, the change of the additive concentration in the etching liquid becomes extremely small, so that the soft etching treatment can be performed more reliably. It has the effect of being able to

The invention according to claim 4 is characterized in that, in particular, before the derusting treatment, the pretreatment is performed with a pretreatment liquid consisting of an aqueous solution containing an organic compound soluble in water. It is a method of manufacturing a wiring board, and by utilizing the lipophilicity that the solder resist originally has in pretreatment,
Good wettability is obtained between the solder resist and the pretreatment liquid containing an organic compound, and air bubbles may adhere between the circuit pattern on which the solder resist is formed in the vicinity or in the vicinity and the pretreatment liquid. Good wettability can be obtained without generation. By performing the next derusting treatment while maintaining the wettability obtained here, the wettability between the derusting treatment liquid and the circuit pattern is also ensured, so the oxide film on the circuit pattern surface is surely removed. It has the effect of being able to.

According to a fifth aspect of the present invention, in particular, the method for producing a printed wiring board according to the first or fourth aspect is performed by immersing the printed wiring board in a pretreatment liquid in which ultrasonic waves are propagated. With this method, the bubbles adhering to the circuit pattern when the printed wiring board is immersed in the pretreatment liquid are removed by the vibration of ultrasonic waves, and good wettability is obtained. Since the wettability between the treatment liquid and the circuit pattern is secured by performing the next soft etching or derusting treatment while maintaining the wettability obtained here,
It has an effect that the oxide film on the surface of the circuit pattern is surely removed.

According to the sixth aspect of the present invention, in particular, the treatment is performed by arranging cylindrical rollers containing a pretreatment liquid in the upper and lower sides and inserting a printed wiring board between them.
Or a method of manufacturing a printed wiring board as described in 4, wherein a roller impregnated with the pretreatment liquid directly contacts the surface of the printed wiring board, whereby bubbles adhere between the circuit pattern and the pretreatment liquid. Will never occur. As a result, good wettability is obtained, and the wettability between the etching solution and the circuit pattern is secured by performing the next soft etching or derusting treatment while maintaining the wettability obtained here. It has an effect that the oxide film on the pattern surface can be surely removed.

The invention according to claim 7 is, in particular, the printed wiring according to claim 1 or 4, wherein the pretreatment liquid is jetted while applying pressure by a spray nozzle, and the printed wiring board is passed between the pretreatment liquid and the treatment. This is a method of manufacturing a plate. By injecting the pretreatment liquid while applying pressure by a spray nozzle, bubbles on the circuit pattern are forcibly removed due to the pressure of the injection. For this reason, good wettability of the pretreatment liquid on the circuit pattern is secured, so that the oxide film on the surface of the circuit pattern can be reliably removed.

The invention according to claim 8 is the method for producing a printed wiring board according to claim 1 or 4, wherein a rust preventive film is formed on the circuit pattern after soft etching or derusting treatment. By forming the rust preventive film after the oxide film on the surface is surely removed, the state of the surface of the circuit pattern is maintained, and good electrical connection can be obtained during solder mounting.

The invention according to claim 9 is the method for producing a printed wiring board according to claim 1 or 4, wherein metal plating is performed on the circuit pattern after soft etching or derusting treatment. By performing the metal plating after the oxide film is reliably removed, there is an effect that good electrical connection can be obtained between the circuit pattern surface and the metal plating.

The tenth aspect of the present invention is a method for producing a printed wiring board according to the first or fourth aspect, in which conductive paste is printed on the circuit pattern after the soft etching or derusting treatment. Since the conductive paste is printed after the oxide film on the surface is surely removed, there is an effect that good electrical connection can be obtained between the surface of the circuit pattern and the conductive paste.

The invention according to claim 11 is, in particular, a method for manufacturing a printed wiring board according to claim 1 or 4, in which a metal pin is brought into contact with a circuit pattern after a soft etching or a derusting treatment to perform an electrical inspection. Yes, this way
After the oxide film on the surface of the circuit pattern has been reliably removed, it is possible to contact the metal pins and perform an electrical inspection.
There is an effect that good electrical connection can be obtained between the surface of the circuit pattern and the metal pin at the time of electrical inspection, and normal electrical inspection can be performed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) Hereinafter, the invention described in claims 1 to 3 and 5 to 11 of the present invention will be described with reference to Embodiment 1 of the present invention.

FIG. 1 is a flowchart of a method for manufacturing a printed wiring board according to the first embodiment of the present invention.

The printed wiring board on which the circuit pattern is formed (FIG. 1A) and the solder resist is formed (FIG. 1B) is exposed to water before the soft etching treatment (FIG. 1D). Pretreatment with an aqueous solution containing a soluble organic compound (Fig. 1
(C)) is performed. It is a feature of this embodiment that this pretreatment is performed before the soft etching treatment.

Soft etching process (FIG. 1 (d))
The etching solution used for is mixed with, for example, an oxo acid composed of sulfuric acid, an oxidizing agent composed of hydrogen peroxide, and an additive composed of an organic compound.

The pretreatment liquid used in the pretreatment process (FIG. 1 (c)) is composed of an additive contained in the etching liquid used in the soft etching treatment process as an organic compound, and the concentration of the additive is in the etching liquid. 0.5 of the concentration contained in
It is diluted with water so that the concentration is about 2 times, preferably the same concentration as the etching solution.

The printed wiring board is immersed in the above-mentioned pretreatment liquid in which ultrasonic waves are propagated, so that pretreatment is performed without generating bubbles between the circuit pattern and the pretreatment liquid (FIG. 1 (c)). ) Is carried out and the wet etching property is maintained and the film is conveyed to the soft etching process step (FIG. 1D).

In the present embodiment, the printed wiring board is soaked in the pretreatment liquid in which ultrasonic waves are propagated. However, cylindrical rollers containing the pretreatment liquid are arranged vertically, In the meantime, the structure to pass the printed wiring board, or spraying the pretreatment liquid while applying pressure with the spray nozzle,
A structure in which a printed wiring board is inserted between them may be used.

Next, the pre-processed printed wiring board is
The soft etching process is performed by jetting an etching solution from a spray nozzle or immersing the etching solution in the etching solution to obtain a printed wiring board from which the oxide film is removed.

The printed wiring board from which the oxide film has been removed by the soft etching treatment is subjected to an electrical test by contacting with metal pins in order to confirm the continuity of the circuit pattern (see FIG. 1).
(E)) is performed, and then the circuit pattern and the chip component are soldered and mounted, so that the rust-preventive film is formed (see FIG.
1)) is applied, and good electrical connection reliability on the circuit pattern is obtained.

In this embodiment, the method of forming the rust preventive film on the circuit pattern after the soft etching treatment has been described, but the method of performing metal plating (see FIG. 1 (f
2)), or a method of printing conductive paste (Fig. 1
(F3)), and the method of performing the electrical inspection (FIG. 1E) is also effective.

As described above, according to the present embodiment, by performing the pretreatment with the pretreatment liquid containing the organic compound contained in the etching liquid before the soft etching treatment,
Good wettability can be obtained without generating bubbles on the circuit pattern, and since soft etching can be performed while maintaining wettability, it is possible to reliably remove the oxide film on the circuit pattern surface. It is possible to obtain a printed wiring board having excellent electrical connection reliability.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be used to explain the invention particularly set forth in claims 4 to 11.

FIG. 2 is a flowchart of a method for manufacturing a printed wiring board according to the second embodiment of the present invention.

The printed wiring board on which the circuit pattern has been formed (FIG. 2A) and the solder resist formed (FIG. 2B) has been treated with water before being subjected to derusting treatment (FIG. 2D). Pretreatment (FIG. 2C) is performed with an aqueous solution containing a soluble organic compound. The feature of the present embodiment is that this pretreatment is performed before the derusting treatment.

The derusting solution used in the derusting step (FIG. 2 (d)) is mixed with oxo acid such as sulfuric acid.

The pretreatment liquid used in the pretreatment step (FIG. 2 (c)) is an aqueous solution of an organic compound soluble in water. The printed wiring board is immersed in the above-mentioned pretreatment liquid in which ultrasonic waves are propagated, so that pretreatment is performed without generating bubbles between the circuit pattern and the pretreatment liquid (see FIG. 2).
(C)) is carried out, and the film is conveyed to the rust treatment step (FIG. 2 (d)) while maintaining the wettability.

In the present embodiment, the printed wiring board is soaked in the pretreatment liquid in which ultrasonic waves are propagated. However, cylindrical rollers containing the pretreatment liquid are arranged vertically. In the meantime, the structure to pass the printed wiring board, or spraying the pretreatment liquid while applying pressure with the spray nozzle,
A structure in which a printed wiring board is inserted between them may be used.

Next, the pre-processed printed wiring board is
The derusting treatment is carried out by spraying a derusting liquid from a spray nozzle or by immersing the derusting liquid in the derusting liquid to obtain a printed wiring board from which the oxide film has been removed.

The printed wiring board from which the oxide film has been removed by the derusting treatment is subjected to an electrical inspection (FIG. 2 (e)) by bringing a metal pin into contact to confirm the continuity of the circuit pattern. Since it is reliably removed, good electrical connection reliability on the circuit pattern can be obtained.

In the present embodiment, the method of contacting the metal pin after the derusting treatment and conducting the electrical inspection has been described. However, the method of forming the rust preventive film on the circuit pattern (see FIG. 2).
(F1)), a method of performing metal plating (FIG. 2 (f2)),
Alternatively, a method of printing a conductive paste (Fig. 2 (f3))
Is also effective in.

As described above, according to this embodiment, bubbles are generated on the circuit pattern by performing the pretreatment with the pretreatment liquid containing the organic compound contained in the derusting liquid before the derusting treatment. It is possible to obtain good wettability without doing so, and because it is possible to perform derusting treatment while maintaining wettability, it is possible to reliably remove the oxide film on the surface of the circuit pattern and it has excellent electrical connection reliability. It is possible to obtain a printed wiring board.

Although sulfuric acid is used as the oxo acid in the above embodiments, oxo acids other than sulfuric acid such as nitric acid, phosphoric acid and boric acid may be used. Although hydrogen peroxide is used as the oxidizing agent, an oxidizing agent such as a peroxo acid or a peroxo acid salt may be used.

[0043]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, by performing pretreatment with a pretreatment liquid consisting of an aqueous solution containing an organic compound soluble in water before the soft etching treatment, a high density product can be obtained. Since the wettability of the etching solution or derusting solution to the circuit pattern exposed on the surface can be maintained, the oxide film on the copper foil surface can be reliably removed in the next soft etching process step, and the conductivity can be improved. It is possible to obtain the effect of realizing a method for manufacturing a printed wiring board having excellent electrical connection reliability after paste printing, metal plating, and soldering mounting.

[Brief description of drawings]

FIG. 1 is a flowchart of a method for manufacturing a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a method for manufacturing a printed wiring board according to a second embodiment of the present invention.

FIG. 3 is a flowchart of a conventional method for manufacturing a printed wiring board.

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Claims (11)

[Claims] 1. A step of forming a circuit pattern of a printed wiring board, a step of forming a solder resist so as to cover the circuit pattern, and a step of forming an oxo acid on the circuit pattern exposed without being covered with the solder resist. It has a step of performing a soft etching treatment with an etching solution containing an oxidant, and is characterized in that it is pretreated with a pretreatment solution consisting of an aqueous solution containing an organic compound soluble in water before the soft etching treatment. And a method for manufacturing a printed wiring board. 2. The method for producing a printed wiring board according to claim 1, wherein the water-soluble organic compound used in the pretreatment liquid is an additive contained in the etching liquid. 3. The method for manufacturing a printed wiring board according to claim 2, wherein the additive concentration of the pretreatment liquid is 0.5 to 2 times the concentration in the etching liquid. 4. A step of forming a circuit pattern of a printed wiring board, a step of forming a solder resist so as to cover the circuit pattern, and a step of forming an oxo acid on the circuit pattern exposed without being covered with the solder resist. Is characterized in that it has a step of performing a derusting treatment with a derusting solution consisting of a pretreatment liquid consisting of an aqueous solution containing an organic compound soluble in water before the derusting treatment. Manufacturing method of printed wiring board. 5. The treatment is performed by immersing the printed wiring board in a pretreatment liquid in which ultrasonic waves are propagated.
Alternatively, the method for manufacturing the printed wiring board according to the item 4, 6. The method for manufacturing a printed wiring board according to claim 1, wherein the cylindrical rollers containing the pretreatment liquid are arranged one above the other, and the printed wiring board is inserted between the rollers to perform the treatment. 7. The method of manufacturing a printed wiring board according to claim 1, wherein the pretreatment liquid is sprayed by a spray nozzle while applying a pressure, and the printed wiring board is passed between the pretreatment liquid and the pretreatment liquid to perform the treatment. 8. The method for manufacturing a printed wiring board according to claim 1, wherein a rust preventive film is formed on the circuit pattern after soft etching or derusting treatment. 9. The method of manufacturing a printed wiring board according to claim 1, wherein metal plating is performed on the circuit pattern after soft etching or derusting treatment. 10. The method for producing a printed wiring board according to claim 1, wherein conductive paste printing is performed on the circuit pattern after soft etching or derusting treatment. 11. The method for manufacturing a printed wiring board according to claim 1, wherein a metal pin is brought into contact with the circuit pattern after the soft etching or the derusting treatment to perform an electrical inspection.