JP2876779B2 - Manufacturing method of thin copper foil-clad circuit board - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a method for manufacturing a thin copper foil-clad circuit board by etching, while vertically transporting a copper-clad circuit board. , By etching
A thin copper foil-clad circuit board having excellent dimensional accuracy, in which variations in etching accuracy due to locations are greatly reduced, is stably manufactured with high productivity.

[Conventional technology and its problems]

The inventors of the present application have previously described JP-A-2-60189, -25090, and -25.
089, -22896, -22887, 2-97688, etc., proposed a method for manufacturing a thin copper foil-clad circuit board.

It is understood that a thin copper-clad circuit board is more effective in manufacturing a printed wiring board having a finer pattern (= fine pattern), and a thickness corresponding to a desired thickness is required in order to form a more advanced fine pattern. There is a demand for one with even smaller variations.

When this purpose is carried out using a horizontal etching machine generally used in the related art, a balance between the etching rates of the upper surface and the lower surface, a variation in the thickness of the upper surface, particularly an insufficient etching at the central portion, and the like occur. This is inconvenient for using large substrates and mass production.

As a solution to this problem, Japanese Patent Application Laid-Open No. 2-97688 has been proposed, but there is an inconvenience that a jig for transportation must be used.

[Means for solving the problem]

The present invention, as a result of earnestly studying a method for manufacturing a thin copper foil-clad circuit board with good productivity that has solved the above disadvantages,
The present invention has been reached.

That is, the present invention provides a thin copper foil which is entirely etched using a copper etchant while a copper foil-clad circuit board (a) manufactured from a copper foil having an average thickness of 12 μm or more and an electrical insulator is vertically set and transported. A method of manufacturing a circuit board, comprising: a feed driver (1) provided at an upper end thereof in a transport direction, and driven by the driver (1). And a roller unit that sandwiches and sends the substrate (a), which includes a number of rollers (4) disposed along the transport direction and on the shaft, and a roller unit ( 4) A transport section (A) for the substrate (a) comprising at least a support roller (7) for the substrate provided at the lower end, and a number of spray nozzles (8) provided on both left and right sides along the transport direction. Having a nozzle portion (B) comprising The substrate (a) is put into a polishing apparatus, and the entire surface of the copper foil is etched at a rate of 0.01 to 0.4 μm / sec, leaving 10 to 80% of the original thickness of the copper foil and remaining to a desired thickness. This is a method for manufacturing a thin copper foil-clad circuit board in which the thickness variation of the copper foil is within ± 1.0 μm, wherein the supporting roller (7) is driven by a drive shaft (5) at the same feed speed as the roller (4). It is driven by a drive shaft (5) at a speed, and two stages of etching zones having the nozzle portion (B) are provided, and an inversion portion (C) of the substrate (a) is provided in the middle thereof. The copper etching solution supplied to the spray nozzle (8) is preliminarily filtered through a filter;
This is a predetermined condition selected from the range of 01 to 03 μm / sec and the spray pressure of 0.3 to 1.3 kg / cm ² .

Further, the copper etching solution used in the present invention is 1.5 to 4 w / v% of hydrogen peroxide, 3 to 7 w / v% of sulfuric acid, 10 to 100 g / copper, and the concentration of hydrogen peroxide, sulfuric acid and copper is a predetermined concentration. The temperature is controlled within ± 1.0%, and the temperature is controlled within ± 1.0 deg. At 25-60 ° C., and the copper etching solution further contains 0.1-5 w / v% of alcohol as an auxiliary agent. That the copper etching solution is cupric chloride 0.25 to 3 mol
/, Hydrochloric acid 1-5 mol / and the concentration of hydrochloric acid ± 0.
This is a method for manufacturing a thin copper foil-clad circuit board by controlling the temperature to within 3 mol / and the temperature to be controlled within ± 5.0 deg. At 25 to 55 ° C.

 Hereinafter, the configuration of the present invention will be described.

First, the copper foil-clad circuit board (a) manufactured from the copper foil and the electrical insulator of the present invention is a copper foil having an average thickness of 12 μm or more, and a thickness variation with respect to the average thickness within ± 1.0 μm. There is no particular limitation as long as it is used, and any of various commercially available products used for electronic and electric materials can be used. One-sided or both-sided copper-clad films, sheets, fiber-reinforced insulating resin laminates, metal Examples include a core laminate, a multilayer shield plate having a printed wiring network formed in an inner layer, and the like.

Here, the electric insulator layer is made of a film or sheet of a polyimide resin or a polyester resin, a thermosetting resin or a heat-resistant thermoplastic resin and glass (E glass, D glass, S glass, quartz glass (quartz) and others). , Ceramics (alumina, boron nitride, etc.), wholly aromatic polyamide, polyimide, semicarbon, fluororesin, other heat-resistant engineering plastics, etc. What is manufactured using a prepreg obtained by combining a porous film or a sheet-like reinforcing substrate, or
Examples include an iron or aluminum plate coated with an insulating adhesive or an adhesive film. In addition, as a method of manufacturing a copper-clad laminate or sheet using thin copper foil of 12 to 16 μm, about 40 to 100 μm of aluminum foil or the like having a larger coefficient of thermal expansion than copper foil between the copper foil and the mirror surface plate The method of inserting the sheet and performing lamination molding is preferable.

The surface of the copper foil of the copper-clad circuit board (a) used in the present invention is clean, that is, the "dust" acting as an etching resist is removed.
If such "dust", particularly resin powder, is adhered, the copper foil at that portion remains without being etched, and a projection is formed. Therefore, in order to remove such “dust”, it is more preferable to use one that has been subjected to mechanical polishing, treatment with a desmear treatment liquid, and the like.

The above-mentioned copper foil-clad circuit board (a) is introduced into a vertical etching machine and etched under a predetermined condition to produce the thin copper foil-clad circuit board of the present invention.

The copper etchant of the present invention used for etching the copper foil-clad circuit board (a) is an aqueous solution mainly containing hydrogen peroxide / sulfuric acid, copper chloride, persulfate, iron chloride, etc. A method of keeping the concentration of the etching component low compared to the etching solution used for etching, a method of keeping the temperature low, a method of making the contact amount of the supplied etching solution on the copper foil surface uniform and small (in the case of the spray method, Lowering the spray pressure) or by appropriately combining the above methods to lower the etching rate, in the range of 0.01 to 0.4 μm / sec, preferably in the range of 0.01 to 0.3 μm / sec, more preferably in the range of 0.03 to 0.2 μm / sec. This is a predetermined etching rate selected from the range of 0.05 to 0.11 μm / sec.

In the present invention, hydrogen peroxide / sulfuric acid-based and copper chloride-based etchants are preferred. Also, the etching rate is 0.4μm
If it is faster than / sec, the progress of etching differs due to a slight difference in etching processing time, not only the difference from the desired thickness becomes large, but also the variation depending on the thickness location tends to increase, the predetermined copper foil thickness It is not preferable because it becomes difficult to make the variation width to ± 1.0 μm or less. On the other hand, if the etching rate is lower than 0.01 μm / sec, the etching takes a long time, which is not practical.

Further, the range of 0.3~1.3kg / cm ² as a spray pressure used to spray the etching, preferably 0.3~0.8kg / c
A range of m ² , especially a range of 0.4 to 0.6 kg / cm ² is suitable. This preferable spray pressure range is smaller than that of ordinary pattern etching and the like, and is smaller than that of a case where a horizontal etching machine is used for overall etching. By using a vertical type, it is possible to apply such a low spray pressure, so that even if the substrate is as thin as 0.1 mm, there is virtually no `` flapping '' of the substrate due to spraying during etching. This enables uniform etching.

In the case of a hydrogen peroxide / sulfuric acid based copper etching solution suitable for the above etching, hydrogen peroxide is 1.5 to 4 w / v%, sulfuric acid is 3 to 7 w / v%, the temperature is 25 to 50 ° C., and the copper concentration is 10 to 100 g / As appropriate, additives such as a stabilizer for hydrogen peroxide and a brightener for copper-monohydric alcohols such as methanol, ethanol, propanol and butanol; ethylene glycol, propylene glycol, butanediol, pentanediol and the like. And dihydric alcohols of glycerin and pentaerythritol. In the case of copper chloride, cupric chloride 0.5
~ 2mol /, hydrochloric acid 1 ~ 3.6mol / aqueous solution temperature 25 ~ 55 ℃
Is preferable as it is particularly used in situ as it is. Further, a method of treating with a cupric chloride-based etching solution and then treating with a hydrogen peroxide / sulfuric acid-based copper etching solution or a chemical polishing solution is exemplified.

The copper foil-clad circuit board (a) described above is etched using a copper etching solution while being transported in a vertically upright state to produce the thin copper foil-clad circuit board of the present invention.

To facilitate understanding of the etching apparatus of the present invention, an example will be described first with reference to the accompanying drawings.

FIG. 1 is a plan view of a vertical etching apparatus used in the present invention, and FIG. 2 is a side view of the same.

In the apparatus shown in FIGS. 1 and 2, the copper foil-clad circuit board (a) is set up from the left side of the drawing and the etching tanks (10, 20)
And a feed drive (11, 21,
12), 22), 13), and a large number of rollers (14, 24) are installed on the left and right sides under the shaft, almost entirely opposed to each other with the shaft in the vertical direction, and are respectively arranged along the transport direction and on the shaft. And a driving unit (15, 25, 1) provided at the lower end of the roller unit.
Support roller for the substrate driven by 6, 26) (17)
The substrate (a) is transported rightward at a predetermined speed by a transporter of at least the substrate (a).

During this transport, dust and the like are substantially removed from a number of spray nozzles (18, 28) provided on both sides of the pump (P) via a filter (F) from a pump (P) and supplied via a pressure regulating valve. The predetermined copper etching solution to be sprayed is sprayed to perform etching so as to fall within the range of the above conditions.

As described above, only the etching device portion is shown in the drawing,
Normally, as described later, it is preferable to add a means for removing the etching solution immediately after the end of the etching (immediately after the spraying) or for stopping the etching ability of the etching solution. Preferably, cleaning, rust prevention, drying, etc. are performed in a series of lines as one continuous device. In addition, the etching can be appropriately performed, for example, by performing multi-stage etching and inserting an inversion mechanism in the middle.

In order to form a copper foil having a predetermined thickness by etching, the etching rate is measured with an etching solution under predetermined etching conditions (such as the type and concentration of the etching solution, the temperature, the spray pressure, and the feed speed of the substrate (a)). Then, a method of setting an etching time and managing an etching solution for maintaining the etching rate is used.
For example, when copper having the same thickness is removed from both surfaces, a method is employed in which the spray pressure on the left and right surfaces is the same and etching is performed for a predetermined time. Further, in order to obtain a copper foil having a predetermined thickness different from each other, the left and right spray pressure or the number of sprays used,
In particular, a method can be used in which the number of sprays is adjusted to set the etching rates on the left and right surfaces to a desired speed ratio within a desired speed range. In addition, as a double-sided copper-clad circuit board used for etching, for example, 35 μm electrolytic copper foil on one side and 18 μm on the other side
A method in which both surfaces are etched at the same rate by using an electroplated copper foil; a peelable protective film such as a plastic film is formed on the entire surface of one side or particularly around the surface using an 18 μm electroplated copper foil on both surfaces. A method of forming and etching only one side; a method of performing a double-sided copper-clad circuit board by standing upright, and the like. Further, the method of completely removing the copper foil on one side and forming the thin copper foil on the opposite side with a desired thickness is the same as the above-described method for forming a copper foil of a predetermined thickness different from each other, except that the etching of the copper foil completely removed side surface is performed. It depends on the method of setting the speed even higher than the above. Further, the cleaning may be a known method of removing impurities such as neutralization, acid washing, water washing, hot water washing,
It is appropriately selected in consideration of the used copper etching solution, its stabilizer and other components, but after washing with a weakly acidic aqueous solution or water at room temperature or under heating, pickling, and then using an aqueous solution of 1 to 5 wt% of sodium carbonate. Neutralize at 20 to 50 ° C. Treat at 20 to 50 ° C with an aqueous solution containing 0.01 to 1% by weight of a known copper rust preventive as a rust preventive and appropriately using a surfactant etc. Is preferred.

Also, after the rust prevention treatment, a resin that can be peeled off, for example, polyethylene, polypropylene, ethylene-propylene resin, ethylene-vinyl acetate resin, vinylidene chloride, polyacrylate copolymer, 1,2-polybutadiene resin, polyester resin, other heat Films and photoresist films made of plastic resin; general-purpose solvent-soluble resins such as paraffin wax, polyethylene wax, rosin, and low molecular weight polystyrene; preferable.

In the above description, the thin copper foil-clad circuit board taken out usually has holes and ends for fixing the frame. This hole,
When it is necessary to remove the end and the like, this part is removed to obtain a product.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The thickness of the copper foil was measured by an eddy current method.

Example 1 100 glass cloth-based epoxy resin laminates each having a 700 × 1020 mm plate thickness of 0.1 mm and a low-profile single-sided copper foil having an average thickness of 15 μm stretched on both sides were prepared. The thin copper foil-clad circuit board having a thickness of 9 μm was manufactured by using the etching apparatus described in the above section, and further using an apparatus in which a water washing or dilute acid washing section, a neutralization treatment section, a rust prevention treatment section, and a drying section were connected.

Here, the etching solution and the etching conditions were set as follows.

・ Etching solution: H ₂ O ₂ concentration 2.1 to 2.4 w / v%. H ₂ SO ₄ concentration 3.6~4.1w / v%. n-propanol concentration 2-4 w / v%. Copper concentration 15-20g /.・ Etching conditions.・ Effective etching chamber length 2.0m. ・ Temperature 35 ± 1 ℃.・ Spray pressure 0.6 kg / cm ^{2 on the} left and right ・ Etching time 67 seconds. (Conveyor speed 1.8m / min.) ・ Etching speed 0.09μm / sec. Then, spray water washing treatment with a 0.01% to 0.05% sulfuric acid aqueous solution at room temperature, spray neutralization treatment with a 5% aqueous solution of Na ₂ CO ₃ at room temperature, and spray rust prevention at 40 ° C with a 0.3% aqueous benzotriazole solution Treated and dried with hot air at 100 ° C.

For all 100 obtained thin copper-clad boards, the copper foil thickness was measured at an arbitrary point in 25 rectangles per sheet obtained by dividing the thickness of the copper foil into five equal parts vertically and horizontally, and the average was 8.9.
μm, maximum 9.3μm, minimum 8.6μm, variation for average thickness is ± 0.4μm, variation for desired thickness is ±
At 0.4 μm, 95% of the measurement points were in the range of 8.7 to 9.3 μm, and the surface irregularities were 2.0 to 3.0 μm.

Further, the obtained thin copper-clad board was kept at 25 ° C. and 60% RH for 30 hours, but no rust was observed.

Example 2 Example 2 was the same as Example 1 except that a thin copper foil-clad circuit board having a thickness of 5 μm was manufactured.

Here, the etching solution and the etching conditions were set as follows.

・ Etching solution: H ₂ O ₂ concentration 2.1 to 2.4 w / v%. H ₂ SO ₄ concentration 3.6~4.1w / v%. n-propanol concentration 2-4 w / v%. Copper concentration 15-20g /.・ Etching conditions.・ Effective etching chamber length 2.0m. ・ Temperature 35 ± 1 ℃.・ Spray pressure 0.6 kg / cm ^{2 on} both sides ・ Etching time 111 seconds. (Conveyor speed 1.08m / min.) ・ Etching speed 0.09μm / sec. For all 100 obtained thin copper-clad boards, the thickness of the copper foil was divided into five equal parts vertically and horizontally.
μm, maximum 5.4μm, minimum 4.6μm, the variation for the average thickness is ± 0.5μm, and the variation for the desired thickness is ±
At 0.4 μm, 95% of the measurement points were in the range of 4.7 to 5.3 μm, and the surface irregularities were 1.8 to 2.6 μm.

Further, the obtained thin copper-clad board was kept at 25 ° C. and 60% RH for 30 hours, but no rust was observed.

[Action and Effect of the Invention]

As described above, according to the vertical etching method of the present invention, the difference in the etching amount due to the difference between the left and right surfaces or the upper and lower positions of the substrate is extremely small, and a large number of the substrates are continuously stable. It is understood that etching is possible. As a result, a thin copper foil-clad substrate having a copper foil thickness accuracy equal to or higher than that of a conventional ultrathin copper foil can be easily manufactured.

Further, since the present invention is excellent in thickness accuracy as described above, it is possible to manufacture an ultra-thin copper-clad laminate, which could be conventionally manufactured only by vapor deposition, etc. The significance is extremely large.

[Brief description of the drawings]

FIG. 1 is a plan view of a vertical etching apparatus used in the present invention, and FIG. 2 is a side view of the same. Symbols and numbers in the figure are 10, 20: etching tank,
11, 21: drive shaft, 12, 22: drive gear, 13, 23: roller drive gear, 14, 24: roller, 15, 25: drive shaft, 16, 26: drive gear, 17: support roller , 18, 28: spray nozzle, P:
Pump, F: indicates a filter.

Continuation of the front page (56) References JP-A-2-128493 (JP, A) JP-A-3-255694 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 3 / 02-3/08

Claims (8)

(57) [Claims] 1. A thin copper foil cladding in which a copper foil clad circuit board (a) manufactured from a copper foil having an average thickness of 12 μm or more and an electrical insulator is vertically etched using a copper etching solution while being transported. A method of manufacturing a circuit board, comprising: a feed driver (1) provided at an upper end thereof in a transport direction, and driven by the driver (1). A roller section which is provided opposite to the longitudinal direction and has a number of rollers (4) arranged along the transport direction and arranged on a shaft; ) And a supporting portion (A) of the substrate (a), which is provided at the lower end of the substrate (a), and a number of spray nozzles (8) provided on both the left and right sides along the transport direction. Etching device having a nozzle portion (B) The substrate (a) is put into
Etching the entire surface of the copper foil at a rate of 01 to 0.4 μm / sec, leaving 10 to 80% of the original copper foil thickness, and the variation of the thickness of the remaining copper foil to the desired thickness is within ± 1.0 μm Of thin copper foil-clad circuit boards. 2. A drive shaft (5) is also provided along the transport direction and beside the support roller (7), and the support roller (7) is
2. The method for manufacturing a thin copper foil-clad circuit board according to claim 1, wherein the circuit is driven by a drive shaft at the same feed speed as the roller in the transport direction. 3. The thin copper according to claim 1, wherein an etching zone having said nozzle portion (B) is provided in two stages, and an inversion portion (C) of said substrate (a) is provided therebetween. Manufacturing method of foil-clad circuit board. 4. The method for producing a thin copper foil-clad circuit board according to claim 1, wherein the copper etching solution supplied to said spray nozzle (8) is preliminarily filtered. 5. The method according to claim 1, wherein said etching is performed at an etching rate of 0.01 to 03.
^2. The method for producing a thin copper foil-clad circuit board according to claim 1, wherein the spray pressure is in the range of 0.3 to 1.3 kg / cm ² . 6. The method according to claim 1, wherein said copper etching is performed with hydrogen peroxide of 1.5 to 4 w / v.
%, Sulfuric acid 3-7w / v%, copper 10-100g / and the concentration of hydrogen peroxide, sulfuric acid and copper are controlled within ± 1.0% of the specified concentration, and the temperature is within ± 1.0deg. At 25-60 ° C. The method for producing a thin copper foil-clad circuit board according to claim 5, which is controlled. 7. The method for producing a thin copper foil-clad circuit board according to claim 6, wherein said copper etching solution contains 0.1 to 5 w / v% of alcohol as an auxiliary agent. 8. The method of claim 1, wherein said copper etching solution is cupric chloride of 0.25 to 3 m.
ol /, hydrochloric acid 1 to 5 mol / and hydrochloric acid concentration ±
It is controlled within 0.3mol /, temperature is ± 5.0deg at 25 ~ 55 ℃.
6. The method for producing a thin copper foil-clad circuit board according to claim 5, wherein the control is performed within the following range.