An etching method of etching solution ice granulation

Abstract

The present invention discloses an etching method for ice granulation of an etching solution, which sequentially includes the following steps: solidifying the etching solution into etching ice cubes; crushing and separating the etching ice cubes into etching ice grains; spraying the etching ice grains onto the area to be etched on the PCB board, and simultaneously blowing air on the etching ice grains during spraying on the side of the PCB board, so that part of the etching ice grains during spraying is liquefied to form a sprayed etching solution, and the unliquefied etching ice grains and the sprayed etching solution continue to be sprayed onto the PCB board. The etching ice grains and the melted etching ice grains of the present invention have relatively low temperatures, reducing the side etching rate; the etching ice grains strike the PCB board surface, improving the etching rate of the etching solution downward and enhancing the etching precision and uniformity.

Description

Technical Field

[0001] The present invention relates to the field of PCBs, and more specifically, to an etching method for ice granulation of etching solution. Background Art

[0002] Etching is a key process for forming circuits on the surface of PCB boards and is an important process in both the inner layer pattern and outer layer pattern steps. By etching away the unwanted copper surface and retaining the required copper surface, circuit patterns can be fabricated. Traditionally, etching was carried out by immersion, which had a high side etching rate. Currently, spraying is commonly used for etching, which has more advantages compared to the immersion method. The pressure exerted by the spray on the PCB board promotes the penetration and corrosion of the etching solution into the unwanted copper surface, reducing the side etching rate.

[0003] Specifically, the etching solution strikes the board surface under the action of spraying. However, during the downward micro-etching process, the etching solution will also spread to both sides. That is, the etching solution not only bites copper downwards but also bites copper on both sides, and the copper covered under the cured dry film will also be affected. Therefore, engineers will reserve a certain width to avoid the impact of side etching on the circuit. The larger the line width and line spacing, the larger the space that can be reserved. However, currently, the integration of PCB boards is getting higher and higher, and there is not enough space to reserve to avoid the impact of side etching. For IC carriers, the requirements for etching accuracy are relatively high. At present, the side etching rate of spraying is about 30%, and the side etching rate is still relatively high, which cannot meet the requirements of customers and results in a high rejection rate of PCB boards. In addition, for copper layers with different thicknesses at different positions, the difference in uniformity will lead to the problem of incomplete etching on one side and over-etching on the other side. Summary of the Invention

[0004] In order to solve the problem of high side etching rate in existing etching, the present invention provides an etching method for ice granulation of etching solution.

[0005] An etching method for ice granulation of etching solution successively includes the following steps:

[0006] Solidify the etching solution into etching ice cubes;

[0007] Crush and separate the etching ice cubes into etching ice grains;

[0008] Spray the etching ice grains onto the area of the PCB board that needs to be etched. At the same time, blow air on the spraying etching ice grains on the side of the PCB board, so that part of the spraying etching ice grains liquefy to form spraying etching solution, and the unliquefied etching ice grains and spraying etching solution continue to be sprayed onto the PCB board. This method reduces the side etching rate and improves the accuracy and uniformity of etching.

[0009] Optionally, the spraying direction is perpendicular to the PCB board. This improves the etching accuracy and uniformity, and the etching effect is good.

[0010] Optionally, the PCB board is placed horizontally, and etching ice particles are sprayed onto the PCB board from above and below the PCB board respectively. Etching is performed on both the upper and lower surfaces of the PCB board simultaneously, improving the etching efficiency.

[0011] Optionally, the spraying pressure above the PCB board is 1.5 - 2.0 kg / cm 2 , and the spraying pressure below the PCB board is 2.0 - 2.5 kg / cm 2 .

[0012] Optionally, an etching solution is solidified into etching ice cubes using a freezer;

[0013] An etching ice crusher is used to crush and separate the etching ice cubes into etching ice particles;

[0014] The etching ice particles are moved to a spraying device through a negative pressure machine and a pipeline, and the spraying device sprays the etching ice particles onto the PCB board. The operation is simple and helps reduce the etching cost.

[0015] Optionally, the diameter of the etching ice particles is 0.05 - 0.1 mm. This helps improve the etching effect and accuracy.

[0016] Optionally, the etching ice cubes are crushed and separated into etching ice particles at a temperature of -5 to 0°C.

[0017] Optionally, the direction of the blowing air is parallel to the PCB.

[0018] Optionally, the distance between the position of the blowing air and the PCB board is 1 - 3 cm.

[0019] Optionally, the temperature of the air blown out by the blowing is 10 - 15°C.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides an etching method with ice granulation of the etching solution. The etching solution is solidified into etching ice cubes, and the etching ice cubes are crushed and separated into etching ice particles. The etching ice particles are sprayed onto the area of the PCB board that needs to be etched, and at the same time, the etching ice particles during spraying are blown on the side of the PCB board. The temperature of the etching ice particles and the melted etching ice particles is relatively low, reducing the side etching rate; the etching ice particles strike the PCB board surface, increasing the downward etching speed of the etching solution and improving the etching accuracy and uniformity. Detailed implementation manners

[0021] To describe the technical solution of the present invention in detail, the technical solutions of the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0022] Embodiment 1:

[0023] This embodiment provides an etching method for ice granulation of an etching solution, which successively includes the following steps:

[0024] S1: Solidify the etching solution into etching ice cubes. The etching solution can be solidified into etching ice cubes by using a freezer.

[0025] Under a pressure of 3000 kPa, use a freezer to quickly solidify the etching solution, converting the etching solution from a liquid state to a solid state.

[0026] S2: Crush and separate the etching ice cubes into etching ice grains.

[0027] Use a vacuum rotary machine to crush and separate the etching ice cubes into etching ice grains. It can be understood that other existing equipment can be used to crush and cut the etching ice cubes into etching ice grains. The diameter of the etching ice grains is 0.05 - 0.1 mm. The prepared etching ice grains are placed in a freezer storage box for storage and standby.

[0028] S3: Spray the etching ice grains onto the area to be etched on the PCB board. At the same time, blow air on the etching ice grains during spraying on the side of the PCB board, so that part of the etching ice grains during spraying liquefies to form a spray etching solution, and the unliquefied etching ice grains and the spray etching solution continue to be sprayed onto the PCB board.

[0029] Move the etching ice grains to the spraying device through a negative pressure machine and a pipeline, and the spraying device sprays the etching ice grains onto the PCB board. The spraying direction is perpendicular to the PCB board. The PCB board is placed horizontally, and the etching ice grains are sprayed onto the PCB from above and below the PCB respectively. The spraying pressure above the PCB board is 1.5 - 2.0 kg / cm 2 , and the spraying pressure below the PCB board is 2.0 - 2.5 kg / cm 2 , considering the influence of gravity, the spraying pressure below the PCB board needs to be greater than the spraying pressure above the PCB board, so that the pressure intensities on the upper surface and the lower surface of the PCB board by the etching ice grains and the spray etching solution are basically the same.

[0030] Under the negative pressure of the negative pressure machine, the pipeline extracts the etched ice particles, and the ejection ports on the ejection device eject the etched ice particles onto the PCB board. The ejection ports are perpendicular to the PCB board, and the etched ice particles vertically impact the PCB board surface, reducing the side etching on both sides, thereby reducing the side etching rate.

[0031] Use a hair dryer to blow air on the etched ice particles during ejection. The temperature of the blown air is 10 - 15°C. The direction of the blowing is parallel to the PCB.

[0032] During the process of the etched ice particles being ejected onto the PCB board surface, they gradually melt into a liquid. The temperature of the ejected etching solution and the etched ice particles is relatively low, so the etching rate will decrease. Also, because the etched ice particles continuously vertically strike the PCB board surface and melt themselves, the etching solution on the PCB board surface is squeezed. Plus, under the influence of the vertical pressure, the etching rate in the vertical direction increases, while the force in the side etching direction on both sides is greatly weakened. This can not only reduce the side etching rate but also ensure the etching speed. After the etched ice particles melt, they flow out through the board surface. A storage tank is placed below the PCB board. The storage tank is used to collect the etching solution. The storage tank is connected to a conduit and pumped to a freezing storage tank under the action of the negative pressure machine to recycle the etching solution.

[0033] The decrease in temperature is equivalent to a decrease in both the side etching speed and the downward etching speed. However, due to the continuous impact of the solid, the pressure increases. Compared with the original, the downward etching speed increases, and the ratio of the side etching speed to the vertical etching speed is smaller, so the side etching rate decreases.

[0034] Example 2:

[0035] This example provides an etching method for granulating an etching solution into ice particles, which successively includes the following steps:

[0036] S1: Freeze the etching solution into etched ice cubes. The etching solution can be frozen into etched ice cubes using a freezer.

[0037] Under a pressure of 3000 kPa, use a freezer to quickly freeze the etching solution, converting the etching solution from a liquid state to a solid state.

[0038] S2: Crush and separate the etched ice cubes into etched ice particles.

[0039] Use a vacuum rotary machine to crush and separate the etched ice cubes into etched ice particles. It can be understood that other existing equipment can be used to crush and cut the etched ice cubes into etched ice particles. The diameter of the etched ice particles is 0.05 - 0.1 mm. The prepared etched ice particles are placed in a freezing storage tank for storage and standby.

[0040] S3: Spray the etched ice particles onto the area of the PCB board that needs to be etched. At the same time, blow air on the etched ice particles during spraying at the side of the PCB board, so that part of the etched ice particles during spraying liquefy to form a spray etching solution, and the unliquefied etched ice particles and the spray etching solution continue to be sprayed onto the PCB board.

[0041] Move the etched ice particles to the spraying device through a negative pressure machine and a pipeline. The spraying device sprays the etched ice particles onto the PCB board. The spraying direction is perpendicular to the PCB board. The PCB board is placed horizontally, and the etched ice particles are sprayed onto the PCB from above and below the PCB respectively. The spraying pressure above the PCB board is 1.5 - 2.0 kg / cm 2 , and the spraying pressure below the PCB board is 2.0 - 2.5 kg / cm 2 . Considering the influence of gravity, the spraying pressure below the PCB board needs to be greater than the spraying pressure above the PCB board so that the pressure intensities of the etched ice particles and the spray etching solution on the upper surface and the lower surface of the PCB board are basically the same.

[0042] Under the negative pressure of the negative pressure machine, the pipeline extracts the etched ice particles, and the spray nozzle on the spraying device sprays the etched ice particles onto the PCB board. The spray nozzle is perpendicular to the PCB board, and the etched ice particles vertically impact the PCB board surface, weakening the side etching on both sides, thereby reducing the side etching rate.

[0043] Use a hair dryer to blow air on the etched ice particles during spraying. The temperature of the blown air is 10 - 15 °C. The blowing direction is parallel to the PCB, and the distance between the blowing position and the PCB board is 1 - 3 cm, that is, the distance between the air outlet of the hair dryer and the PCB board is 1 - 3 cm.

[0044] During the process of spraying the solid particle etched ice particles onto the surface of the PCB board, blow air on the side of the PCB board. The temperature of the blown air is 10 - 15 °C, and gradually melt the solid particle etched ice particles into liquid. Because of the influence of temperature, the etched ice particles in the form of ice gradually melt into liquid. Also because the temperature is relatively low, the etching efficiency of the etching solution is related to temperature. A low temperature will lead to a lower etching rate. As the etched ice particles continuously strike the etching solution on the PCB board surface, it prompts the etching solution to continuously move vertically downward, and the side etching on both sides slows down compared with normal, which is equivalent to indirectly increasing the vertical downward etching speed and reducing the side etching speed.

[0045] A decrease in temperature means that both the side etching speed and the downward etching speed decrease. However, due to the continuous impact of solids, the pressure increases. Compared with the original, the downward etching speed increases, the ratio of the side etching speed to the vertical etching speed is smaller, and the side etching rate decreases.

[0046] Example 3:

[0047] This embodiment provides an etching method with etched liquid granulation by ice, which successively includes the following steps:

[0048] S1: Solidify the etched liquid into etched ice cubes. The etched liquid can be solidified into etched ice cubes by using a freezer.

[0049] Under a pressure of 3000 kPa, use a freezer to quickly solidify the etched liquid, transforming the etched liquid from a liquid state to a solid state.

[0050] S2: Crush and separate the etched ice cubes into etched ice particles.

[0051] Use a vacuum rotary machine to crush and separate the etched ice cubes into etched ice particles. It can be understood that other existing equipment can be used to crush and cut the etched ice cubes into etched ice particles. The diameter of the etched ice particles is 0.05 - 0.1 mm. Under a temperature of -5 to 0 °C, crush and separate the etched ice cubes into etched ice particles to avoid the melting of the etched ice cubes or etched ice particles, resulting in inconsistent sizes of the etched ice particles. The prepared etched ice particles are placed in a freezer storage box for standby.

[0052] S3: Spray the etched ice particles onto the area of the PCB board that needs to be etched. At the same time, blow air on the etched ice particles during spraying on the side of the PCB board, so that part of the etched ice particles during spraying liquefies to form sprayed etched liquid, and the unliquefied etched ice particles and the sprayed etched liquid continue to be sprayed onto the PCB board.

[0053] Move the etched ice particles to the spraying device through a negative pressure machine and a pipeline. The spraying device sprays the etched ice particles onto the PCB board. The spraying direction is perpendicular to the PCB board. The PCB board is placed horizontally, and the etched ice particles are sprayed onto the PCB from above and below the PCB respectively. The spraying pressure above the PCB board is 1.5 - 2.0 kg / cm 2 , and the spraying pressure below the PCB board is 2.0 - 2.5 kg / cm 2 . Considering the influence of gravity, the spraying pressure below the PCB board needs to be greater than the spraying pressure above the PCB board, so that the pressure intensities of the etched ice particles and the sprayed etched liquid on the upper surface and the lower surface of the PCB board are basically the same.

[0054] Under the negative pressure of the negative pressure machine, the pipeline extracts the etched ice particles, and the spraying nozzle on the spraying device sprays the etched ice particles onto the PCB board. The spraying nozzle is perpendicular to the PCB board, and the etched ice particles vertically impact the PCB board surface, weakening the side etching on both sides, thereby reducing the side etching rate.

[0055] Use a hair dryer to blow air on the etched ice particles during spraying. The temperature of the blown air is 10 - 15 °C. The blowing direction is parallel to the PCB board, and the distance between the blowing position and the PCB board is 1 - 3 cm, that is, the distance between the air outlet of the hair dryer and the PCB board is 1 - 3 cm.

[0056] During the process of spraying etched ice particles onto the PCB board surface, the etched ice particles gradually melt into liquid. The temperature of the sprayed etching solution and the etched ice particles is relatively low, so the etching rate will decrease. Also, because the etched ice particles continuously strike the PCB board surface vertically and melt themselves, the etching solution on the PCB board is squeezed. Additionally, affected by the vertical pressure, the etching rate in the vertical direction increases, while the etching force in the two side etching directions is greatly weakened, which can not only reduce the side etching rate but also ensure the etching speed. After the etched ice particles melt, they flow out through the board surface. A storage tank is placed below the PCB board, and the storage tank is used to collect the etching solution. The storage tank is connected to a conduit and pumped to a refrigerated storage tank under the action of a negative pressure machine to recycle the etching solution repeatedly.

[0057] During the process of spraying solid particle etched ice particles onto the surface of the PCB board, air is blown on the side of the PCB board, and the temperature of the blown air is 10 - 15 °C. The solid particle etched ice particles are gradually melted into liquid. Because of the influence of temperature, the ice particle etched solution gradually melts into liquid. Also, because the temperature is relatively low, the etching efficiency of the etching solution is related to temperature, and a low temperature will lead to a lower etching rate. As the etched ice particles continuously strike the etching solution on the PCB board surface, it promotes the etching solution to continuously move vertically downward, while the side etching speed on both sides is reduced compared to normal, which indirectly increases the vertical downward etching speed and reduces the side etching speed.

[0058] A decrease in temperature means that both the side etching speed and the downward etching speed decrease. However, due to the continuous impact of the solid, the pressure increases. Compared with the original situation, the downward etching speed increases, and the ratio of the side etching speed to the vertical etching speed is smaller, so the side etching rate decreases.

[0059] The present invention provides an etching method for granulating an etching solution into ice particles. The etching solution is solidified into etched ice blocks, and the etched ice blocks are crushed and separated into etched ice particles. The etched ice particles are sprayed onto the area to be etched on the PCB board. At the same time, air is blown on the side of the PCB board for the sprayed etched ice particles. The temperature of the etched ice particles and the melted etched ice particles is relatively low, which reduces the side etching rate; the etched ice particles strike the PCB board surface, which increases the downward etching speed of the etching solution and improves the etching accuracy and uniformity.

[0060] Testing verifies that this method can reduce the side etching rate. Twelve PCB boards are selected and divided into four groups, with three PCB boards in each group. The difference in copper thickness range after electroplating of the PCB boards in Group 1 and Group 2 does not exceed 3 microns. Then, pattern making is carried out. Group 1 is etched by the conventional spray etching solution method, and Group 2 is etched by this method. The difference in copper thickness range after electroplating of the PCB boards in Group 3 and Group 4 exceeds 5 microns. Group 3, like Group 1, is etched by the conventional spray etching solution method, and Group 4 is etched by this method. Ten positions are selected for etching on each PCB board. In this experiment, the four corners and the center positions on the upper and lower surfaces of the PCB board are selected for etching, and the copper thickness at each position is determined, that is, there are 30 etching positions in each group.

[0061] Table 1, four groups of data, with 3 PCB boards in each group, and the copper thickness (microns) at 10 positions on each PCB board, as shown in the following table:

[0062]

[0063] Table 2, four groups of data, with 3 PCB boards in each group, and the side etching rate (%) after etching at 10 positions on each PCB board, as shown in the following table:

[0064]

[0065] Comparing Table 1 and Table 2, it is found that in the comparison of the two groups of experiments where the difference in copper thickness range does not exceed 3 microns, when etching is carried out by the method of the present invention, the side etching rate can be reduced to about 10%, which is far less than 30% of the existing technology in Group 1; in the comparison of the two groups of experiments where the difference in copper thickness range exceeds 5 microns, when etching is carried out by the method of the present invention, the side etching rate can be reduced to 11 - 14%, which is far less than 30 - 36% of the existing technology in Group 3.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0067] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this embodiment are all included within the protection scope of the present invention.

Claims

1. An etching method with ice granulation of etching solution, Characterized in that: It successively includes the following steps: Solidify the etching solution into etching ice cubes; Crush and separate the etching ice cubes into etching ice grains; Spray the etching ice grains onto the area to be etched on the PCB board, and at the same time blow air on the etching ice grains during spraying on the side of the PCB board, so that part of the etching ice grains during spraying liquefy to form sprayed etching solution, and the unliquefied etching ice grains and the sprayed etching solution continue to be sprayed onto the PCB board; the spraying direction is perpendicular to the PCB board, and the vertical etching speed of the etching ice grains on the PCB board is greater than the side etching speed.

2. An etching method with ice granulation of etching solution according to claim 1, Characterized in that: The PCB board is placed horizontally, and the etching ice grains are sprayed on the PCB from above and below the PCB respectively.

3. An etching method with ice granulation of etching solution according to claim 2, Characterized in that: The spraying pressure above the PCB board is 1.5 - 2.0 kg / cm2, and the spraying pressure below the PCB board is 2.0 - 2.5 kg / cm2.

4. An etching method with ice granulation of etching solution according to claim 1, Characterized in that: Use a freezer to solidify the etching solution into etching ice cubes; Use a vacuum rotary machine to crush and separate the etching ice cubes into etching ice grains; Move the etching ice grains to the spraying device through a negative pressure machine and a pipeline, and the spraying device sprays the etching ice grains onto the PCB board.

5. An etching method with ice granulation of etching solution according to claim 1, Characterized in that: The diameter of the etching ice grains is 0.05 - 0.1 mm.

6. An etching method with ice granulation of etching solution according to claim 1, Characterized in that: Crush and separate the etching ice cubes into etching ice grains at a temperature of -5 to 0 °C.

7. An etching method with ice granulation of etching solution according to claim 1, Characterized in that: The blowing direction is parallel to the PCB.

8. An etching method with ice granulation of etching solution according to claim 7, Characterized in that: The distance between the blowing position and the PCB board is 1 - 3 cm.

9. An etching method with ice granulation of etching solution according to claim 1, 7 or 8, Characterized in that: For the blowing, the temperature of the blown air is 10 - 15 °C.

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