JPH11214825A - Method of treating surface of circuit board for inner layers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good appearance and improve productivity, by feeding a treating liq. to a circuit on the surface of a long inner layer circuit board being conveyed. SOLUTION: An inner layer circuit board 1 is guided from an unwinder 10 to a surface treating machine 11 which then treats circuits on the surface of the inner layer circuit board 11, and the inner layer circuit board 11 is guided to a winder 12. The unwinder 10 has an unwinding shaft 13 having a brake such as powder brake and tension controller 14 which moves up and down like a dancer roll to apply to the inner layer circuit board 11. A part nearest to the unwinder 10 in the surface treating machine 11 is formed as an entrance 18. Next to an acid treating part 21, a dripping part 23 is formed, next to the dripping part, a first water washing part 24 is formed, and using a treating liq. contg. carboxylic acid, Cu ion and chelating agent of Cu ion, the Cu-made circuit surface is dissolved and roughened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a surface of an inner layer circuit board used as an inner layer of a multilayer printed wiring board.

[0002]

2. Description of the Related Art Conventionally, one inner layer circuit board or a plurality of inner layer circuit boards is bonded and laminated to form an inner layer, and a copper foil or an outer layer circuit board or the like serving as an outer layer is formed on the inner layer. It is performed to form a multilayer printed wiring board by bonding and laminating, but in order to increase the adhesive strength between the inner layer circuit boards and the adhesive strength between the inner layer circuit board and the copper foil or the outer layer circuit board, Circuits on the surface of the inner layer circuit board are subjected to surface treatment. The surface treatment is a treatment for oxidizing the surface of the circuit or roughening the surface of the circuit. Conventionally, these treatments are performed in a batch system or a continuous system.

In performing the surface treatment in a batch system, first, a multilayer material (metal foil-clad laminate) formed by laminating a metal foil on the surface of an insulating layer (resin-impregnated base material) is sized. (300 mm x 300 mm to 1000 mm x
(About 1000 mm) to form a short sheet, and then perform an etching process or the like on the metal foil to form a circuit on the surface of the substrate to form a circuit board for an inner layer. By immersing the circuit board for use in the processing liquid at a time, the circuit is oxidized or roughened with the processing liquid. When performing the surface treatment in a continuous manner, an inner circuit board is formed in the same manner as in the batch method, and thereafter, a large number of inner circuit boards are continuously fed using a conveyor such as a belt conveyor. Meanwhile, the circuit is oxidized or roughened with the processing liquid by spraying the processing liquid onto the inner layer circuit board by spraying or the like.

[0004]

However, when the surface treatment is carried out in a batch system, only a certain number of circuit boards for the inner layer can be treated at a time, and there is a problem that the productivity is low. In the case of an ultra-thin circuit board for an inner layer having a thickness of 0.1 mm or less, the circuit board for an inner layer may be deflected or displaced and come into contact with another circuit board for an inner layer. There is a problem that a portion where the treatment liquid does not sufficiently act on the circuit is formed, and it is difficult to obtain an inner layer circuit board having a uniform appearance (that is, an inner layer circuit board having a uniform surface treatment).

[0005] Even when the surface treatment is performed in a continuous manner, an extremely thin circuit board for the inner layer is easily caught by the transfer device, and the clogging causes a decrease in productivity or damage to the circuit board for the inner layer. There was a problem that was damaged. The present invention has been made in view of the above points, and an object of the present invention is to provide a surface treatment method for an inner layer circuit board capable of obtaining an inner layer circuit board having high productivity and a uniform and good appearance. It is assumed that.

[0006]

According to a first aspect of the present invention, there is provided a method for treating a surface of an inner layer circuit board, the method comprising: transporting a long inner layer circuit board; The process liquid is supplied to the apparatus. According to the surface treatment method for an inner layer circuit board according to the second aspect of the present invention, in addition to the configuration of the first aspect, the tension applied to the inner layer circuit board 1 is reduced by one.
It is characterized in that the inner layer circuit board 1 is transported while being adjusted to 50 kgf.

According to a third aspect of the present invention, there is provided a method for treating a surface of an inner layer circuit board, wherein
An acidic aqueous solution containing a carboxylic acid, copper ions and a chelating agent for copper ions is used as the treatment liquid. The surface treatment method for an inner layer circuit board according to claim 4 of the present invention, in addition to the configuration according to any one of claims 1 to 3, further comprises a transport roll 2 for transporting the inner layer circuit board 1 for the inner layer. The circuit board 1 is provided at intervals of 40 to 500 mm in the transport direction.

[0008]

Embodiments of the present invention will be described below. The inner layer circuit board 1 is formed in a long sheet shape by providing a circuit on the surface of the insulating layer, and the insulating layer is formed to be extremely thin with a thickness of 0.04 to 0.1 mm. Such an inner layer circuit board 1 is formed, for example, by performing an etching process on a long glass cloth / glass non-woven fabric base copper-clad laminate or a long glass cloth base copper-clad laminate to form a copper foil into a circuit. It is formed. The inner layer circuit board 1 is supplied to a surface treatment device in a state of being wound in a roll shape.

FIG. 1 shows a surface treatment apparatus used in the present invention. This surface treatment device derives the inner layer circuit board 1 from the unwinder 10 to the surface treatment machine 11, processes the circuit on the surface of the inner layer circuit board 1 with the surface treatment machine 11, and then removes the inner layer circuit board 1. It is configured to be introduced into the winder 12.
The unwinding machine 10 is provided with an unwinding shaft 13 provided with a brake device such as a powder brake. The unwinding machine 10 is provided with a tension controller 14 that adjusts the tension applied to the inner layer circuit board 1 by moving up and down like a step roll.

At the end of the surface treatment machine 11 on the unwinder 10 side, an inlet 15 is provided.
An outlet 16 is formed at the end on the side of the first winder 12, and a number of transport rolls 2 are arranged substantially horizontally from the inlet 15 toward the outlet 16 inside the surface treatment machine 11. Has been established. A guide roll 17 is provided above some of the transport rolls 2. And this surface treatment machine 1
The inside of 1 is divided into a plurality of portions from the inlet 15 to the outlet 16.

A portion closest to the unwinding machine 10 inside the surface treatment machine 11 is formed as an introduction portion 18, and a foil 19 such as a star wheel is arranged in parallel with the transport roll 2 in the introduction portion 18. In addition, a motor 20 such as an induction motor for rotating and driving the transport roll 2 is provided below the transport roll 2. This introduction 1
8 is formed as an acid treatment section 21. Above the guide roll 17 and below the transport roll 2 of the acid treatment section 21, a plurality of spray nozzles 22 for spraying an acidic aqueous solution as a treatment liquid are provided. Are arranged side by side along the transport direction of the circuit board 1.

The acid treatment section 21 is formed as a draining section 23, and the adjoining section is formed as a first washing section 24. The first washing section 24 is provided with a guide roll 17 from the guide roll 17. On the upper side, a spray nozzle 25 for injecting water is provided. A pickling unit 26 is formed adjacent to the first water washing unit 24, and a plurality of spray nozzles 27 for spraying an acidic cleaning liquid are provided above the guide roll 17 and below the transport roll 2 of the pickling unit 26. Have been.

A second washing section 28 is formed adjacent to the pickling section 26. A plurality of spray nozzles 29 are provided above the guide roll 17 and below the transport roll 2 of the second washing section 28. ing. The third washing section 30 is formed adjacent to the second washing section 28, and a plurality of spray nozzles 31 are provided above the guide roll 17 and below the transport roll 2 of the third washing section 30. .

A draining portion 32 is formed adjacent to the third washing portion 30, and a sponge roll 33 is provided in the draining portion 32 alongside the guide roll 17 and the transport roll 2. Adjacent to the draining part 32 is formed as a draining slit part 34 such as an air curtain or an air blow, and a motor 20 such as an induction motor for driving the transport roll 2 is provided below the draining slit part 34. I have. The drying section 35 is formed next to the draining slit section 34, and the drying section 3 is formed.
Next to 5 is formed as a carry-out portion 36 provided with the outlet 16.

The winder 12 has an inlet 37 formed at a position facing the outlet 16, and a detector for detecting the presence or absence of the inner layer circuit board 1 outside the winder 12 near the inlet 37. 38 are provided. A pinch roll 39 connected to a servomotor is provided inside the winder 12 near the entrance 37. Further, inside the winding machine 12, a winding shaft 40 for winding the inner layer circuit board 1 is rotatably driven by a driving device, and a pinch roll 39 and a winding shaft 4 are provided.
Edge position controller (EPC) between 0
41 are provided.

The treating solution used in the acidic treating section 21 is an acidic aqueous solution containing a carboxylic acid, copper ions and a chelating agent for copper ions, and dissolves the surface of a circuit formed of copper to roughen the surface. Things. As described above, in an acidic aqueous solution containing a copper ion and a chelating agent of copper ions, a divalent copper ion and a chelating agent form a complex, and when copper is reacted with this treatment solution, a reaction represented by the following formula (a) is obtained. Is believed to occur and the copper dissolves. The complex of the monovalent copper ion and the chelating agent generated by the reaction of the formula (a) is an unstable complex as compared with the complex of the divalent copper ion and the chelating agent. It is thought that oxygen in the air is absorbed and reacts to form a complex of a divalent copper ion and a chelating agent, as shown in FIG. In these reactions, since the reaction proceeds rapidly at the part where the reaction has begun, the amount of dissolution may differ depending on the position of the circuit, and the difference may cause irregularities on the surface to roughen the surface. I have.

[0017]

Embedded image

Examples of the above chelating agent for copper ion include ethylenediaminetetraacetic acid, cyclohexanediaminetetraacetic acid, 1,10-phenanthroline, 8-hydroxyquinoline and the like. In addition, it is preferable that the acidic aqueous solution contains a carboxylic acid having 1 to 5 carbon atoms such as formic acid or acetic acid, because the reactivity for roughening is excellent, and the treatment time can be shortened. The acidic aqueous solution may contain a wetting agent, a rust preventive, and the like.

The content of the copper ion or the copper ion chelating agent in the acidic aqueous solution is determined by roughening the surface of the copper circuit using an acidic aqueous solution containing a carboxylic acid, copper ion and a copper ion chelating agent. In this case, the concentration of the carboxylic acid is generally preferably 10 to 100 g / l, the concentration of the copper ion is preferably 15 to 25 g / l, and the concentration of the chelating agent for the copper ion is
Preferably it is 0.1 to 10 grams / liter.
Further, the pH is preferably from 1 to 4, and the liquid temperature during the treatment is preferably from 30 to 45 ° C.

The surface treatment of the circuit of the inner layer circuit board 1 is performed as follows. First, the inner layer circuit board 1 attached to the unwinding shaft 13 of the unwinding machine 10 is introduced from the introduction port 15 into the introduction section 18 of the surface treatment machine 12. Next, the inner layer circuit board 1 is conveyed to the outlet 16 side by the rotation of the conveying roll 2 while being guided by the guide roll 17, and is introduced into the acid processing section 21. Here, the processing liquid is sprayed and supplied to the inner layer circuit board 1 from the upper and lower spray nozzles 22, and the surface of the circuit is roughened by the action of the processing liquid as described above.

Thereafter, the inner layer circuit board 1 is introduced into the liquid draining section 23, where the processing liquid adhering to the inner layer circuit board 1 is naturally dropped. Next, the inner layer circuit board 1 is
Where the spray nozzle 2 is attached to the inner layer circuit board 1.
Water is sprayed from 5 and washed. Next, the inner layer circuit board 1
Is introduced into an acid washing section 26, where an acidic washing liquid such as hydrochloric acid is sprayed from a spray nozzle 27 onto the inner layer circuit board 1 to be washed. Next, the inner layer circuit board 1 is introduced into the second washing section 28, where the spray nozzle 29 is applied to the inner layer circuit board 1.
Then, water is sprayed at a higher water pressure than that of the first water washing section 24 to be washed. Next, the inner layer circuit board 1 is
Where the spray nozzle 3
Pure water is sprayed from 1 and washed.

Thereafter, the inner layer circuit board 1 is introduced into the draining section 32, where the sponge roll 33 is attached to the inner layer circuit board 1.
By pressing, the adhered water is removed. Next, the inner layer circuit board 1 is introduced into the draining slit portion 34, where air is blown to the inner layer circuit board 1 to further remove water. Next, the inner layer circuit board 1 is introduced into the drying unit 35, and is dried by supplying heat to the inner layer circuit board 1 or the like. Thereafter, the inner layer circuit board 1 is led out of the surface treatment machine 11 from the outlet 16 through the carry-out part 36.

Next, the surface treated inner layer circuit board 1 is
It is introduced into the winder 12 from the inlet 37 and wound up in a roll shape by a windup shaft 40. Circuit board for inner layer 1
A pinch roll 39 is in contact with the upper surface of the substrate 1 to adjust the position and the position of the inner layer circuit board 1. The winding position of the inner layer circuit board 1 in the width direction is adjusted by the edge position controller 41. Then, the surface of the circuit of the inner-layer circuit board 1 can be continuously processed by unwinding and transporting the long inner-layer circuit board 1 sequentially to the surface treatment machine 11 while unwinding. Thereafter, the long surface-treated inner layer circuit board 1 is cut into a predetermined size to be used as a circuit board for forming an inner layer of a multilayer printed wiring board.

As described above, in the present invention, the processing liquid is supplied to the circuit on the surface of the inner circuit board while the long inner circuit board is being conveyed. The surface can be roughened, and the productivity can be increased as compared with the batch type. In addition, the inner layer circuit board 1 can be prevented from contacting other parts by reducing the bending and displacement of the inner layer circuit board 1 and the inner layer circuit board 1 can be prevented from being caught. The circuit board for use can be obtained.

The time for treating the circuit using the acidic aqueous solution is preferably adjusted by adjusting the contact time between the circuit and the acidic aqueous solution according to the change in the concentration of copper ions contained in the acidic aqueous solution. If the time of contact between the circuit and the acidic aqueous solution is not adjusted according to the variation in the concentration of copper ions contained in the acidic aqueous solution, the amount of copper dissolved will vary, and the adhesive strength will vary between the resulting laminates. It will be easier.
The "time of contact between the circuit and the acidic aqueous solution" indicates the time during which the acidic aqueous solution is sprayed on the circuit and the acidic aqueous solution is in contact with the circuit.

As a method of adjusting the contact time between the circuit and the acidic aqueous solution in accordance with the fluctuation of the concentration of the copper ion contained in the acidic aqueous solution, the treatment may be carried out as follows. The time during which the circuit is in contact with the acidic aqueous solution is reduced by, for example, decreasing the injection amount of the acidic aqueous solution, and when the concentration of copper ions is reduced, the time during which the circuit is in contact with the acidic aqueous solution is extended.

This is because most of the copper ions in the acidic aqueous solution are present as divalent copper ions that are more stable than the monovalent copper ions. It is believed that the concentration of multivalent copper ions increases mainly. When the concentration of the divalent copper ion increases, the reaction of the above formula (a) is promoted to maintain chemical equilibrium, and the dissolution rate of copper increases. Therefore, by reducing the amount of copper dissolved by reducing the time that the circuit and the acidic aqueous solution contact, the amount of copper dissolved within the shortened time,
It is possible to make the amount of copper dissolved before the concentration of copper ions increase approximately the same.

Conversely, when the concentration of copper ions in the acidic aqueous solution decreases, the reaction of the above formula (a) becomes difficult to proceed,
The dissolution rate of copper decreases. Therefore, if the amount of copper dissolved in the extended time is increased by increasing the amount of acidic aqueous solution sprayed from the spray and extending the contact time between the circuit and the acidic aqueous solution, the amount of copper dissolved within the extended time In addition, the amount of copper dissolved before the concentration of copper ions decreases can be made substantially the same. When the amount of copper dissolved is stabilized in this way, the size of the unevenness on the surface of the circuit formed by the dissolution of copper is also stabilized, and it is possible to obtain a laminated board with a small variation in adhesive strength. Become.

The time for treating the circuit with the acidic aqueous solution is preferably adjusted within the range where the surface roughness of the portion of the circuit treated with the acidic aqueous solution is 2 to 6 μm. When the thickness is less than 2 μm, the variation in the bonding strength is small, but the bonding strength may be low as a whole.
When the value exceeds, the thickness of the circuit may be reduced and the electrical reliability may be reduced.

Further, when the treatment is carried out by spraying an acidic aqueous solution onto the circuit, the treatment time can be shortened more than other methods such as immersion, which is preferable. If necessary, before the treatment with an acidic aqueous solution, the surface of the circuit is mechanically polished or chemically polished such as ammonium persulfate or copper chloride, washed, and then treated with an acidic aqueous solution. Is also good.

The tension applied to the conveyed inner layer circuit board 1 is preferably 1 to 50 kgf. The tension can be adjusted by the vertical movement of the tension controller 14 and the driving force of a driving device that rotationally drives the winding shaft 40. When the tension is less than 1 kgf, the inner layer circuit board 1 bends and the transportability is reduced. Therefore, there is a possibility that the productivity may be lowered, and a portion where the processing liquid is not sufficiently supplied to the inner layer circuit board 1 may be formed, and the appearance may be deteriorated. On the other hand, when the tension exceeds 50 kgf, the force applied to the inner layer circuit board 1 is too large, and the inner layer circuit board 1 may be torn or damaged, and both productivity and appearance may be reduced.

Further, the pitch (interval) of the transport roll 2
Is preferably 40 to 500 mm. If the pitch is less than 40 mm, the interval between the transport rolls 2 is too small, and there is a possibility that a portion where the processing liquid is not sufficiently supplied to the inner layer circuit board 1 is formed, and the appearance may be deteriorated. The pitch is 500
If it exceeds mm, there is a possibility that the transportability is reduced and the productivity is reduced.

[0033]

The present invention will be described below in detail with reference to examples. (Examples 1 to 9) A glass cloth / glass nonwoven base epoxy resin copper-clad laminate having a size of 0.5 × 80 m and a thickness of an insulating layer excluding copper foil of 0.07 mm (trade name, manufactured by Matsushita Electric Works, Ltd.) R5766) is etched to 30 × 100
A pattern (circuit) in which a copper foil of mm was left was formed near the four corners, and a plurality of land patterns having a diameter of 1.5 mm were formed.

As a treatment liquid, a copper hydroxide concentration of 15 g / g was dissolved in a treatment liquid (trade name: CZ8100, manufactured by Mec Co., Ltd.) containing a carboxylic acid, copper ions and a chelating agent for copper ions. Liter, pH 3.
The acidic aqueous solution prepared in 5 was used. The long inner layer circuit board 1 was wound into a roll and supplied to the surface treatment apparatus shown in FIG. 1 to perform the surface treatment of the copper foil circuit. Tables 1 and 2 show the magnitude of the tension and the pitch of the transport roll 2 at this time. The temperature of the processing solution was controlled at 38 ° C., and after spraying, washing was carried out with water so that the contact time between the circuit and the processing solution was 165 seconds. Drying is 80
C., at 30 minutes.

COMPARATIVE EXAMPLE The long internal circuit board 1 of Example 1 was cut into a size of 300 × 300 mm to form a short internal circuit board 1 in the form of a sheet. The surface treatment of the copper foil circuit was performed using the surface treatment apparatus shown in FIG. Then, in Examples 1 to 9 and Comparative Example, the yield of the processed inner layer circuit board 1 was measured. The yield is based on the total amount of the processed inner layer circuit board 1.
It is expressed by the amount of the inner-layer circuit board 1 that has been satisfactorily processed. The closer to 100%, the better the yield. The transportability of the inner layer circuit board 1 was visually checked. Further, the appearance of the circuit of the inner layer circuit board 1 after the treatment was evaluated. The numbers in parentheses in the appearance column of Tables 1 and 2 are as follows:
The percentage of circuits with poor appearance is shown.

[0036]

[Table 1]

[0037]

[Table 2]

As is clear from Tables 1 and 2, in Examples 1 to 5 in which the tension conditions and the transport roll pitch were within the predetermined ranges, the yield, transportability, and appearance were all good. Further, in Examples 6 to 9 in which the tension condition and a part of the pitch of the transport roll were out of the predetermined range, some problems occurred, but the overall evaluation was higher than the comparative example. still,
A glass substrate epoxy resin prepreg having a thickness of 0.06 mm and a resin amount of 50% (trade name: R-166, manufactured by Matsushita Electric Works Co., Ltd.)
1) were laminated one by one, and a copper foil having a thickness of 12 μm was further laminated on both outer sides thereof.
When a laminate was prepared by heating and pressing under the conditions of ° C., a pressure of 2.9 MPa and a time of 60 minutes, the adhesive strength between the inner layer made of the inner layer circuit board 1 and the outer layer (copper foil) outside the inner layer was high.
No problems such as peeling occurred.

[0039]

As described above, according to the first aspect of the present invention, the treatment liquid is supplied to the circuit on the surface of the inner layer circuit board while the long inner circuit board is being conveyed. The circuit of the circuit board for the inner layer of the shaku can be continuously roughened, and the productivity can be increased as compared with the batch type. In addition, it is possible to reduce the deflection and displacement of the inner layer circuit board so that the inner layer circuit board does not come into contact with other parts and to reduce the possibility of the inner layer circuit board being caught. A plate can be obtained.

According to the second aspect of the present invention, since the inner layer circuit board is transported while adjusting the tension applied to the inner layer circuit board to 1 to 50 kgf, the inner layer circuit board is not damaged. In addition, surface treatment can be performed without lowering productivity. Further, the invention according to claim 3 of the present invention uses an acidic aqueous solution containing a carboxylic acid, a copper ion and a copper ion chelating agent as a treatment liquid, and therefore contains both a copper ion and a copper ion chelating agent. By using the processing liquid, the surface of the circuit can be easily roughened.

In the invention according to claim 4 of the present invention, the transport rolls for transporting the inner layer circuit board are provided at intervals of 40 to 500 mm in the transport direction of the inner layer circuit board. The circuit board can be conveyed without bending and in a state in which the processing liquid is sufficiently supplied, and an inner layer circuit board having a uniform and good appearance can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention.

[Explanation of symbols]

 1 inner layer circuit board 2 transport roll

Claims (4)

[Claims] 1. A method for treating a surface of an inner layer circuit board, comprising supplying a treatment liquid to a circuit on the surface of the inner layer circuit board while transporting a long inner layer circuit board. 2. The tension applied to the inner layer circuit board is 1 to 50 k.
The surface treatment method for an inner layer circuit board according to claim 1, wherein the inner layer circuit board is transported while adjusting to gf. 3. The surface treatment method for an inner layer circuit board according to claim 1, wherein an acidic aqueous solution containing a carboxylic acid, copper ions and a chelating agent for copper ions is used as the treatment liquid. 4. The inner layer circuit according to claim 1, wherein transport rolls for transporting the inner layer circuit board are provided at intervals of 40 to 500 mm in the transport direction of the inner layer circuit board. Surface treatment method for circuit boards.