TWI557274B - Method for etching printed circuit board - Google Patents

Description

Substrate etching treatment method

The invention relates to a substrate etching treatment method, in particular to a substrate etching treatment method capable of solving the pool effect and realizing ultrafine line etching.

With the trend of light, thin, high-density and thin-line of electronic products, the distance between the width of the line and the line is relatively narrower and finer; the etching technology of the printed circuit board has higher requirements for refinement. Some advanced electronic products require wiring to be as thin as 1.5 mils or less, which poses an unprecedented challenge to board etching technology, even because the product cannot achieve the desired accuracy and yield, which has led to the impediment of the introduction of such advanced electronic products. How to ensure that the etching effect is thinner, it is becoming more and more important to achieve ultra-fine.

In the etching apparatus and method in the prior art, since the roller hinders the discharge of the etching liquid, the etching effect between the rollers causes the etching effect of the upper and lower plates of the horizontal line device to be different. Specifically, the etch rate of the edge of the board is faster than the etch rate of the middle of the board. In some cases, a serious imbalance may result, resulting in a large difference between the upper and lower board etch factors (Etch Factor, E.F). On the other hand, when the thin line is reduced in the line pitch, the syrup and the like are prevented from being etched by the surface tension, and the syrup does not easily enter between the fine lines.

At present, there are two methods, one is the method of spraying up and down by the layering method, and the other is to use the copper etching method to make the copper surface thin. However, the effect of the two methods is not good, and the etching quality of the line cannot be effectively improved.

On the whole, the prior art faces several problems.

1. Pudling Effect:

Referring to FIG. 1A, there is often a problem of the pool effect in the prior art, that is, the syrup or the like is easily accumulated in the first region 710 of the central portion of the substrate 700. In contrast, the fourth region 740 of the edge portion of the substrate 700 is relatively etched. Further, the first region 710 of the substrate 700 is not easily removed due to the blocking of the waste liquid such as the medicated water, so that the fresh syrup cannot be hit on the copper surface. Since the etching action is caused by the transition from copper metal to copper ions, which belongs to an oxidation effect, the first region 710 is hindered by the syrup and reduces the oxygen-assisted oxidation; therefore, the thickness of the central portion on a substrate 700 Thicker, the thickness of the surrounding edges is thinner. That is, the thickness of the first region 710 > the second region 720 > the third region 730 > the thickness of the fourth region 740.

2. The etch factor (E.F) is low:

The Etch Factor (E.F.) is an index of etching quality. The calculation formula is: 2 times copper thickness / (lower line width - upper line width). Referring to the window side in FIG. 3A, the side of the substrate 600 near the window of the etching processing apparatus is shown. The middle of the board represents the intermediate portion of the substrate 600, and the inner side represents the side near the inside of the etching processing apparatus. The bottom end of the upper line 610 of the substrate 600 has a residual portion 611, which is known in the industry as a residual foot. The relationship between the copper thickness D1, the upper line width W3, and the lower line width W4 determines the etching factor. The etch factors in the prior art are 1.866, 2.735, and 2.792, respectively, as indicated by the dashed lines in FIG. 3A. In general, the larger the etching factor, the better. However, the etching factor in the prior art is only 2.792, which cannot meet the requirement of an etching factor greater than 4.

3. Fine line etching is not possible:

The industry uses L/S to represent the etched line capability. Please refer to Figure 2A, where L0 is the line width and S0 is the pitch. The etching treatment method in the prior art has an etching ability L0/S0 of 30 μm / 30 μm, which is a technical bottleneck. Unable to meet the requirements of ultra-fine lines and thin lines, that is, the technical requirements of L/S less than 25μm/25μm.

In view of this, the present inventors have felt that the above-mentioned deficiency can be improved, and it is a research and cooperation with the application of the theory, and finally proposes a present invention which is rational in design and effective in improving the above-mentioned deficiency.

The main object of the present invention is to provide a substrate etching treatment method which can effectively solve the pool problem, the etching factor is up to 4 or more, and can realize ultra-fine line etching with L/S less than 25 μm/25 μm.

The substrate etching treatment method of the present invention comprises the following steps. Provide working syrup to the two-fluid blasting device. A working gas is supplied to the two-fluid blasting device. Mix working syrup and working gas to generate gas-liquid mixed spray. The gas-liquid mixed spray mist is supplied to the surface of the substrate, and the working syrup remaining on the surface of the substrate is sucked by a vacuum suction device.

In an embodiment of the invention, the particle size of the working syrup in the gas-liquid mixed spray is Q, wherein 10 μm < Q < 50 μm.

In an embodiment of the invention, the method further comprises the step of providing a transport device for linearly moving the substrate relative to the two-fluid erosion device.

In an embodiment of the invention, a plurality of two-fluid erosion devices are disposed, a plurality of vacuum suction devices are disposed, and vacuum suction devices are respectively disposed on opposite sides of the two fluid erosion devices.

In an embodiment of the invention, the vacuum suction device is provided with a plurality of arrangements in which the two fluid erosion devices and the vacuum suction device are spaced apart from each other.

The invention has the following technical effects, and uses the vacuum suction device to continuously suck away the residual etching liquid on the substrate, thereby promoting the fresh drug exchangeability of the substrate, thereby improving the uniformity of etching. By injecting a strong fine mist and mixing high-pressure air through the two-fluid etching device, the etchant and the like are sprayed onto the substrate to etch the line, thereby realizing the etching operation of the ultra-fine line. Therefore, the substrate etching treatment method provided by the invention completely solves the problem of the pool effect, greatly improves the etching factor, and can produce an ultra-precision line etching with an L/S of less than 25 μm/25 μm, and obtains uniform etching with uniform line height. Sexual technical effects.

In order to further understand the features and technical aspects of the present invention, reference should be made to the detailed description of the invention and the accompanying drawings. The invention is not to be construed as limiting the scope of the invention.

100‧‧‧Two fluid erosion device

110‧‧‧Two-fluid erosion module

111‧‧‧Two fluid nozzle

112‧‧‧ first entrance

113‧‧‧second entrance

200‧‧‧Vacuum suction device

300‧‧‧Conveyor

400‧‧‧Substrate

410‧‧‧ lines

500‧‧‧Two fluid erosion device

600‧‧‧Substrate

610‧‧‧ lines

611‧‧‧ Residue

700‧‧‧Substrate

710‧‧‧First District

720‧‧‧Second District

730‧‧‧ Third District

740‧‧‧Fourth District

800‧‧‧Substrate

810‧‧‧First District

900‧‧‧Roller

L0, L1‧‧‧ line width

S0, S1‧‧‧ spacing

D1‧‧‧ line thickness

W1, W3‧‧‧Upline width

W2, W4‧‧‧ offline width

S100-S500‧‧‧ Process steps

FIG. 1A is a schematic diagram of the pool effect of a substrate in the prior art.

1B is a schematic view of a substrate of a substrate etching treatment method of the present invention.

2A is a cross-sectional view of a substrate in a prior art.

2B is a cross-sectional view of a substrate of a substrate etching treatment method of the present invention.

FIG. 3A is a graph of experimental data of an etch factor in the prior art.

3B is experimental data of an etch factor of a substrate etching treatment method of the present invention.

4 is a flow chart of a substrate etching process of the present invention.

5A is a first schematic view of a substrate etching apparatus of a substrate etching processing method of the present invention.

5B is a second schematic view of a substrate etching apparatus of the substrate etching processing method of the present invention.

6 is a third schematic view showing a substrate etching apparatus of the substrate etching processing method of the present invention.

The following is a specific embodiment to explain the embodiment of the present invention relating to the "substrate etching treatment method". The following embodiments will further explain the related technical content of the present invention, but the disclosure is not intended to be limiting. The technical scope of the present invention.

Referring to FIG. 4, the substrate etching processing method of the present invention comprises the following steps. In step S100, a working fluid is provided to a two-phase mixture etching apparatus, and a two-fluid etching apparatus is a two-fluid etching apparatus having a two-fluid nozzle, which is called a gas-assisted type. The nozzle is a nozzle that utilizes the principle of high-speed flow of compressed air to assist the liquid atomization, unlike a single-fluid nozzle that only pumps the liquid with a pump. Next, in step S200, a working gas is supplied to the two-fluid etching device. Then, in step S300, the working syrup and the working gas are mixed to generate a gas-liquid mixed spray. In step S400, the gas-liquid mixed spray is supplied to The surface of the substrate. In step S500, the working syrup remaining on the surface of the substrate is sucked by the vacuum suction device.

In an embodiment of the invention, the particle size of the working syrup in the gas-liquid mixed spray is defined as Q, wherein 10 μm < Q < 50 μm.

In an embodiment of the invention, there is further provided a step of providing a transport device for linearly moving the substrate relative to the two fluid erosion device. As shown in Fig. 5A, the transport device 300 can transport a substrate 400 such as a flexible circuit board from the left side of the drawing to the right of the drawing. Further, in an embodiment of the present invention, the substrate 400 is exemplified by a roll-to-roll flexible circuit board, and the substrate 400 is rolled by the conveying device 300, so that the substrate 400 is opposed to the two-fluid etching device. 100 performs linear motion. A plurality of rollers 900 are disposed below the substrate 400 for guiding the linear motion of the substrate 400.

Referring to FIG. 5A, FIG. 5B, and FIG. 6, an etching processing apparatus for the substrate etching processing method of the present invention is provided, which includes one or more two-fluid etching apparatuses 100, and one or more vacuum suction apparatuses 200.

In an embodiment of the invention, the two-fluid erosion device 100 and the vacuum suction device 200 are disposed above the substrate 400.

In an embodiment of the invention, the two-fluid erosion device 100 is provided with two or more, one of the two-fluid erosion devices 100 is disposed above the substrate 400, and the other two-fluid erosion device 500 is disposed on the substrate. Below the 400. Through the above arrangement, the line etching operation can be simultaneously performed on the top side and the bottom side of the substrate 400.

In one embodiment of the present invention, a plurality of two-fluid erosion devices 100 are provided, a plurality of vacuum suction devices 200 are disposed, and opposite sides of the two-fluid erosion device 100 are respectively provided with vacuum suction devices 200. In an embodiment of the invention, the two fluid erosion device 100 is spaced from the vacuum suction device 200. In detail, when the two-fluid etching device 100 sprays the gas-liquid mixed spray to the surface of the substrate 400, the vacuum suction device 200 disposed on both sides of the two-fluid etching device 100 continuously absorbs the residue on the substrate 400. The working syrup on the surface, so that the surface of the substrate 400 can continuously receive fresh syrup, that is, gas-liquid mixed spray fog, thereby obtaining good Etching effect. Thereby, the pool effect problem in the prior art can be completely solved.

Referring to FIG. 5A and FIG. 5B, the two-fluid eroding device 100 can receive an externally supplied working syrup and a working gas. Working syrups include, but are not limited to, various etching syrups and deionized water, and the working gases include, but are not limited to, nitrogen or other gases. The two-fluid blasting device 100 includes a plurality of two-fluid blasting modules 110. Each of the two-fluid blasting modules 110 has a two-fluid nozzle 111, and the working syrup is filled from the first inlet 112 into the two-fluid blasting module 110. The working gas is filled from the second inlet port 113 into the two-fluid blasting module 110. In the operation process, the high-pressure working gas is used as the power, and the auxiliary working water is micro-atomized. The average spray particle size is fine, and the finest is 10~20μm (micron meter).

In an embodiment of the present invention, the two-fluid erosive device 100 performs a left-right rocking motion, so that the two-fluid nozzle 111 of the two-fluid blasting module 110 is sprayed with gas-liquid mixed spray fog and sprayed on the base. A predetermined area on the material 400.

In one embodiment of the invention, the distance of the two-fluid nozzle 111 from the surface of the substrate 400 is greater than the distance from the vacuum suction device 200 to the surface of the substrate 400. In other words, the discharge port of the two-fluid nozzle 111 is higher than the suction port of the vacuum suction device 200. The intention is to allow the two-fluid nozzle 111 to have a predetermined distance away from the surface of the substrate 400 in order to spray a larger area. In contrast, the suction port of the vacuum suction device 200 must be close to the surface of the substrate 400 to facilitate the absorption of the working syrup remaining on the surface of the substrate 400.

Referring to FIG. 1B, the substrate etching treatment method provided by the present invention proves that the residual portion of the working syrup is rarely used, such as the first region 810 on the substrate 800. Compared to the prior art of FIG. 1A, the first zone 810 of the working potion remaining in the embodiment of the present invention is compared to the first zone 710, the second zone 720, the third zone 730, and the fourth zone of FIG. 1A. 740, the area occupied by the residual working syrup of the invention is greatly reduced, and the problem of the pool effect in the prior art is completely solved.

As shown in FIG. 3B, the substrate etching treatment method of the present invention has an etching factor of 4.418, 6.826, and 5.808. Etching factor compared to the prior art of FIG. 3A All of them are 4 or less, and the etching factor of the present invention is 4 or more. The problem of the low etching factor in the prior art is also solved. As shown in FIG. 2B, in an embodiment of the present invention, the line 410 on the substrate 400 has a greatly reduced residual phenomenon. The L/S of the present invention, that is, the line width L1/S1 is less than or equal to 25 μm/25 μm, compared with the technical bottleneck of 30 μm/30 μm of L0/S0 of FIG. 2A, the substrate etching treatment method provided by the present invention fully satisfies Ultra-fine line requirements.

[Possible effects of the examples]

In summary, the present invention uses a vacuum suction device to continuously remove the residual etchant solution on the substrate, thereby promoting the exchange rate of the fresh syrup of the substrate to improve the uniformity of etching. By injecting a strong fine mist and mixing high-pressure air through the two-fluid etching device, the etchant and the like are sprayed onto the substrate to galvanize, thereby achieving the etching operation of the ultra-fine line. The substrate etching treatment method provided by the invention completely solves the problem of the pool effect, greatly improves the etching factor, and can produce an ultra-precision line etching with an L/S of less than 25 μm/25 μm, and obtains the technical effect of uniform etching uniformity of the line height. .

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Therefore, equivalent technical changes made by using the present specification and the contents of the drawings are included in the protection scope of the present invention. .

S100-S500‧‧‧ Process steps

Claims (10)

A substrate etching treatment method comprising the steps of: providing a working syrup to a two-fluid blasting device; providing a working gas to the two-fluid eroding device; mixing the working syrup and the working gas to generate a gas-liquid mixture Spraying the mist; supplying the gas-liquid mixed spray mist to the surface of a substrate; and drawing the working syrup remaining on the surface of the substrate through a vacuum suction device. The substrate etching treatment method according to claim 1, wherein the particle diameter of the working syrup in the gas-liquid mixed spray is Q, wherein 10 μm < Q < 50 μm. The substrate etching processing method of claim 1, further comprising the step of providing a conveying device for linearly moving the substrate relative to the two-fluid etching device. The substrate etching treatment method according to claim 1, wherein the two-fluid etching device and the vacuum suction device are disposed above the substrate. The substrate etching processing method of claim 1, wherein two of the two-fluid etching devices are disposed, one of the two-fluid etching devices is disposed above the substrate, and the other two-fluid etching device It is disposed below the substrate. The substrate etching processing method of claim 1, wherein the two-fluid etching device is provided in plurality, the vacuum suction device is provided in plurality, and the vacuum is disposed on opposite sides of the two-fluid etching device Attraction device. The substrate etching processing method according to claim 1, wherein the two-fluid etching device is provided in plurality, and the vacuum suction device is provided in plurality, and the two-fluid etching device and the vacuum suction device are arranged at intervals from each other. The substrate etching processing method of claim 1, wherein the two-fluid etching device comprises a plurality of two-fluid etching modules, and each of the two-fluid etching modules has a Two fluid nozzles. The substrate etching processing method of claim 8, wherein the two-fluid etching device performs a left-right rocking motion, and the gas-liquid mixed spray sprayed by the two-fluid nozzle is sprayed on the substrate to a predetermined one. region. The substrate etching treatment method of claim 1, wherein a distance of the two-fluid nozzle to a surface of the substrate is greater than a distance of the vacuum suction device to a surface of the substrate.