Patent Description:
The invention relates to the technical field of solar cell manufacturing, and to a liquid-carrying roller for wet etching and a wet etching method.

In recent years, production technology of solar cell sheets has been continuously improved, production costs have been continuously reduced, and cell efficiency has been continuously increased, so an application of photovoltaic power generation becomes increasingly popular and develops rapidly, and gradually becomes an important source of power supply. An etching is an important process for preparing silicon solar cell sheets, and aims to remove PN junctions and phosphorosilicate glass on a front of a cell, and etching quality directly affects conversion efficiency of a cell sheet. The current etching methods for silicon wafers mainly include dry etching and wet etching, wherein the production process of the wet etching is as follows: as for a silicon solar cell sheet that has been subjected to diffusion, a mixed acid solution of HNOs and HF in an etching tank is used to etch the lower surface and edge of the silicon wafer so as to achieve edge insulation.

The existing wet etching process is usually formed by connecting a series of tank modules, which are sequentially etching tank→water washing tank <NUM>--*alkali tank→water washing tank <NUM>→acid tank→water washing tank <NUM>→drying. At present, most of wet etching devices suitable for the wet etching process adopt a roller transmission manner, and on the wet etching device, shafts at both ends of a liquid-carrying roller are generally directly inserted into bracket holes to achieve the rotation of the roller to thereby achieve transfer of a silicon wafer from loading to unloading. After long-term use, the diameter of the roller will become small due to wear, which results in that the running silicon wafer cannot move horizontally during transportation, and affects the etching quality of the solar cell sheet; meanwhile, a water film covering the upper surface of the silicon wafer will also slide into a chemical solution due to the unevenness of the rollers, which results in abnormal concentration, and will also affect the etching effect. Deviations of machining precision of a bracket and machining precision of rollers of an etching tank will cause abnormalities in levelness of individual rollers, and affect the overall etching effect.

<CIT> discloses a liquid-carrying roller of the prior art.

In view of the aforesaid analysis, embodiments of the invention aim to provide a liquid-carrying roller for wet etching and a wet etching method for solving the problem of abnormal roller levelness in a process of manufacturing a solar cell in the prior art.

On the one hand, the invention provides a liquid-carrying roller for wet etching, comprising a first end shaft, a second end shaft, and a liquid-carrying shaft, the first end shaft and the second end shaft being located at both ends of the liquid-carrying shaft, respectively, the first end shaft, the second end shaft and the liquid-carrying shaft being arranged concentrically, and the diameters of the first end shaft and the second end shaft being both adjustable.

Further, the first end shaft includes a plurality of first wedges, a plurality of second wedges, a first brake, a second brake, and a first central shaft.

Further, the first brake and the second brake are both sleeved on the first central shaft, the first brake is connected to the first wedges, the second brake is connected to the second wedges, and one end of the first central shaft is connected to the central hole of the liquid-carrying shaft.

Further, the second end shaft includes a plurality of third wedges, a plurality of fourth wedges, a third brake, a fourth brake, and a second central shaft.

Further, the third brake and the fourth brake are both sleeved on the second central shaft, the third brake is connected to the third wedges, the fourth brake is connected to the fourth wedges, and one end of the second central shaft is connected to the central hole of the liquid-carrying shaft.

Further, the first wedges and the second wedges are arranged alternately, the side surfaces of the first wedges are always in contact with the side surfaces of the second wedges, the third wedges and the fourth wedges are arranged alternately, and the side surfaces of the third wedges are always in contact with the side surfaces of the fourth wedges.

Further, the first brake and the second brake can move oppositely along the first central shaft.

Further, the first wedges can move in the radial direction of the first brake, and the second wedges can move in the radial direction of the second brake.

Further, the third brake and the fourth brake can move oppositely along the second central shaft.

Further, the third wedges can move in the radial direction of the third brake, and the fourth wedges can move in the radial direction of the fourth brake.

Further, the first wedges and the second wedges define a first outer surface forming the first end shaft;
the third wedges and the fourth wedges define a second outer surface forming the second end shaft.

Further, the first outer surface has a first effective diameter, which increases or decreases in accordance with an axial movement between the first wedges and the second wedges; the second outer surface has a second effective diameter, which increases or decreases in accordance with an axial movement between the third wedges and the fourth wedges.

Further, the material of the first end shaft, the second end shaft and the liquid-carrying shaft is PVDF or PTFE.

On the other hand, the invention provides a wet etching method, the aforesaid liquid-carrying roller for wet etching being used, the method comprising:.

As compared with the prior art, the invention may achieve at least one of the following advantageous effects:.

In the invention, the aforesaid technical solutions may be also combined with each other to achieve more preferred combination solutions. Other features and advantages of the invention will be illustrated in the Description that follows, and some advantages may be obvious in the Description, or may be understood by carrying out the invention.

Figures are only used to show objects of specific embodiments, and are not considered as limitations of the invention, which is defined by the appended claims. In all of the figures, the same reference sign expresses the same component.

The preferred embodiments of the invention are described in detail below in combination with the figures.

In the descriptions of the embodiments of the invention, it should be noted that unless otherwise specified and limited, the term "connect" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connected, a direct connection, or an indirect connection via an intermediate medium. Those skilled in the art may understand the specific meaning of the aforesaid term in the invention according to specific conditions.

The terms "top", "bottom", "above. ", "lower" and "on. " used throughout the descriptions refer to positions relative to the components of the apparatus, such as relative positions of top and bottom substrates inside the apparatus. It may be understood that the apparatus is multifunctional independent of the orientations of the components in the space.

A specific embodiment of the invention, as shown in <FIG>, discloses a liquid-carrying roller for wet etching, comprising a first end shaft <NUM>, a second end shaft <NUM>, and a liquid-carrying shaft <NUM>, the first end shaft <NUM> and the second end shaft <NUM> being located at both ends of the liquid-carrying shaft <NUM>, respectively, the first end shaft <NUM>, the second end shaft <NUM> and the liquid-carrying shaft <NUM> being arranged concentrically, and the diameters of the first end shaft <NUM> and the second end shaft <NUM> being both adjustable.

As compared with that in the prior art, when abnormal roller levelness is resulted in due to wear of the both ends of the liquid-carrying roller for wet etching provided by the embodiment or machining precision of an etching tank, the diameters of the both ends of the separate liquid-carrying roller may be adjusted in real time to ensure horizontal placement of the liquid-carrying roller on the bracket, which can greatly reduce operating costs of a wet etching device while guaranteeing quality during solar cell etching.

In the embodiment, the first end shaft <NUM> and the second end shaft <NUM> are collectively referred to as the end shaft, the first brake <NUM>, the second brake <NUM>, the third brake <NUM> and the fourth brake <NUM> are collectively referred to as the brake, and the first wedge <NUM>, the second wedge <NUM>, the third wedge <NUM> and the fourth wedge <NUM> are collectively referred to as the wedge.

The first end shaft <NUM> includes a plurality of first wedges <NUM>, a plurality of second wedges <NUM>, a first brake <NUM>, a second brake <NUM>, and a first central shaft <NUM>, the first brake <NUM> and the second brake <NUM> are both sleeved on the first central shaft <NUM>, the first brake <NUM> is connected to the first wedges <NUM>, the second brake <NUM> is connected to the second wedges <NUM>, the first central shaft <NUM> is connected to the central hole of the liquid-carrying shaft <NUM>, and one end of the first central shaft <NUM> is provided with a first stopper, which is a regular hexahedron structure and is arranged in the central hole of the liquid-carrying shaft <NUM> to limit rotation of the first end shaft <NUM> relative to the liquid-carrying shaft <NUM>.

The first wedge <NUM> is composed of a first arc surface, a second arc surface, two non-parallel side surfaces and two parallel end surfaces, the second wedge <NUM> is composed a third arc surface, a fourth arc surface, two non-parallel side surfaces and two parallel end surfaces, the first arc surfaces of the first wedges <NUM> and the third arc surfaces of the second wedges <NUM> form the outer circumference of the first end shaft <NUM>, and the side surfaces of the first wedges <NUM> and the side surfaces of the second wedges <NUM> that are adjacent are in close contact with each other.

It should be noted that the first arc surfaces are concentric with the second arc surfaces, and the third arc surfaces are concentric with the fourth arc surfaces, so that the outer circumferential surface formed by the first end shaft <NUM> is a cylindrical surface, which prevents the first end shaft <NUM> from forming a linear contact with an installation hole <NUM> of a bracket <NUM> of a wet etching tank after being assembled therewith.

In order to achieve that the diameter of the first end shaft <NUM> may be adjusted, the first brake <NUM> and the second brake <NUM> are slidably connected to the first central shaft <NUM>.

To be specific, the first brake <NUM> includes first telescopic rods and a first connecting seat, the first connecting seat is cylindrical and is sleeved on the outside of the first central shaft <NUM>, and the diameter of the inner hole of the first connecting seat is equal to the diameter of the first central shaft <NUM>, so that the first connecting seat can move on the first central shaft <NUM> under an action of an external force.

In the embodiment, the action of the external force that enables the first brake <NUM> to move relative to the first central shaft <NUM> is that an operator manually moves the first brake <NUM>, so that the first brake <NUM> can be stopped at a desired position to make the diameter of the first end shaft <NUM> be of a diameter size required for the adjustment to the horizontal state.

The first telescopic rods are evenly distributed on the outer circumference of the first connecting seat, one end of the first telescopic rod is connected to the first connecting seat, and the other end thereof is a free end, which is telescopic relative to the fixed end. To be specific, the second arc surface of the first wedge <NUM> is provided with a first installation hole, which is arranged at an end close to the big end of the first wedge <NUM>, and the free end of the first telescopic rod is installed in the first installation hole.

To be specific, the first telescopic rod includes a first telescopic spring, a first inner telescopic rod and a first connecting rod, one end of the first connecting rod is provided with a hole and a cavity is formed in the first connecting rod, the first telescopic spring is arranged in the cavity, the other end of the first connecting rod is fixedly connected to the first connecting seat, one end of the first inner telescopic rod enters the cavity through the hole in the first connecting rod and presses against the first telescopic spring, and the other end of the first inner telescopic rod is connected to the first wedge <NUM>.

It should be noted that the extension line of the fixed end of the first telescopic rod passes through the axis center of the first connecting seat, that is, the first telescopic rod is arranged vertically in the radial direction of the first connecting seat.

The second brake <NUM> includes second telescopic rods and a second connecting seat, the second connecting seat is cylindrical and is sleeved on the outside of the first central shaft <NUM>, and the diameter of the inner hole of the second connecting seat is equal to the diameter of the first central shaft <NUM>, so that the second connecting seat can move on the first central shaft <NUM> under an action of an external force.

In the embodiment, the action of the external force that enables the second brake <NUM> to move relative to the first central shaft <NUM> is that an operator manually moves the second brake <NUM>, so that the second brake <NUM> can be stopped at a desired position to make the diameter of the first end shaft <NUM> be of a diameter size required for the adjustment to the horizontal state.

The second telescopic rods are evenly distributed on the outer circumference of the second connecting seat, one end of the second telescopic rod is connected to the second connecting seat, and the other end thereof is a free end, which is telescopic relative to the fixed end. To be specific, the fourth arc surface of the second wedge <NUM> is provided with a second installation hole, which is arranged at an end close to the big end of the second wedge <NUM>, and the free end of the second telescopic rod is installed in the second installation hole.

To be specific, the second telescopic rod includes a second telescopic spring, a second inner telescopic rod and a second connecting rod, one end of the second connecting rod is provided with a hole and a cavity is formed in the second connecting rod, the second telescopic spring is arranged in the cavity, the other end of the second connecting rod is fixedly connected to the second connecting seat, one end of the second inner telescopic rod enters the cavity through the hole in the second connecting rod and presses against the second telescopic spring, and the other end of the second inner telescopic rod is connected to the second wedge <NUM>.

In the embodiment, the first telescopic rods are automatically telescopic along with the movement of the first brake <NUM>, and the second telescopic rods are automatically telescopic along with the movement of the second brake <NUM>. Since the side surfaces of the first wedges <NUM> and the second wedges <NUM> are in contact with each other, the telescopic amounts of the first telescopic rods and the second telescopic rods can be defined under acting forces of the first wedges <NUM> and the second wedges <NUM>, that is, when the positions of the first brake <NUM> and the second brake <NUM> are fixed, the first telescopic rods and the second telescopic rods can maintain a specific length under actions of pressing forces of the side surfaces of the first wedges <NUM> and the second wedges <NUM>.

It should be noted that the second telescopic rods are in the diameter directions of the second connecting seat.

It should be noted that the external force that causes the first brake <NUM> and the second brake <NUM> to move relative to the first central shaft <NUM> is not limited to a manual operation, and any driving manner that can make the first brake <NUM> and the second brake <NUM> move relative to the first central shaft <NUM> is allowed.

In the embodiment, the first brake <NUM> controls the movement of the first wedges <NUM>, and the second brake <NUM> controls the movement of the second wedges <NUM>. When the first end shaft <NUM> is worn, which causes the diameter of the first end shaft <NUM> to decrease, under the actions of the first telescopic rods and the second telescopic rods, the first wedges <NUM> and the second wedges <NUM> move outwards in the radial direction of the first end shaft <NUM>, and the first brake <NUM> and the second brake <NUM> are manually moved, so that the first brake <NUM> and the second brake <NUM> move oppositely along the first central shaft <NUM>, the side surfaces of the first wedges <NUM> are in close contact with the side surfaces of the second wedges <NUM>, and the first arc surfaces of the first wedges <NUM> and the third arc surfaces of the second wedges <NUM> form the outer circumference of the first end shaft <NUM> having a new diameter.

The second end shaft <NUM> includes a plurality of third wedges <NUM>, a plurality of fourth wedges <NUM>, a third brake <NUM>, a fourth brake <NUM>, and a second central shaft <NUM>, the third brake <NUM> and the fourth brake <NUM> are both sleeved on the second central shaft <NUM>, the third brake <NUM> is connected to the third wedges <NUM>, the fourth brake <NUM> is connected to the fourth wedges <NUM>, the second central shaft <NUM> is connected to the central hole of the liquid-carrying shaft <NUM>, and one end of the second central shaft <NUM> is provided with a second stopper, which is a regular hexahedron structure and is arranged in the central hole of the liquid-carrying shaft <NUM> to limit rotation of the second end shaft <NUM> relative to the liquid-carrying shaft <NUM>.

The third wedge <NUM> is composed of a fifth arc surface, a sixth arc surface, two non-parallel side surfaces and two parallel end surfaces, the fourth wedge <NUM> is composed a seventh arc surface, an eighth arc surface, two non-parallel side surfaces and two parallel end surfaces, the fifth arc surfaces of the third wedges <NUM> and the seventh arc surfaces of the fourth wedges <NUM> form the outer circumference of the second end shaft <NUM>, and the side surfaces of the third wedges <NUM> and the side surfaces of the fourth wedges <NUM> that are adjacent are in close contact with each other.

It should be noted that the fifth arc surfaces are concentric with the sixth arc surfaces, and the seventh arc surfaces are concentric with the eighth arc surfaces, so that the outer circumferential surface formed by the second end shaft <NUM> is a cylindrical surface, which prevents the second end shaft <NUM> from forming a linear contact with the installation hole <NUM> of the bracket <NUM> of the wet etching tank after being assembled therewith.

In order to achieve that the diameter of the second end shaft <NUM> may be adjusted, the third brake <NUM> and the fourth brake <NUM> are slidably connected to the second central shaft <NUM>.

To be specific, the third brake <NUM> includes third telescopic rods and a third connecting seat, the third connecting seat is cylindrical and is sleeved on the outside of the second central shaft <NUM>, and the diameter of the inner hole of the third connecting seat is equal to the diameter of the second central shaft <NUM>, so that the third connecting seat can move on the second central shaft <NUM> under an action of an external force.

In the embodiment, the action of the external force that enables the third brake <NUM> to move relative to the second central shaft <NUM> is that an operator manually moves the third brake <NUM>, so that the third brake <NUM> can be stopped at a desired position to make the diameter of the second end shaft <NUM> be of a diameter size required for the adjustment to the horizontal state.

The third telescopic rods are evenly distributed on the outer circumference of the third connecting seat, one end of the third telescopic rod is connected to the third connecting seat, and the other end thereof is a free end, which is telescopic relative to the fixed end. To be specific, the sixth arc surface of the third wedge <NUM> is provided with a third installation hole, which is arranged at an end close to the big end of the third wedge <NUM>, and the free end of the third telescopic rod is installed in the third installation hole.

To be specific, the third telescopic rod includes a third telescopic spring, a third inner telescopic rod and a third connecting rod, one end of the third connecting rod is provided with a hole and a cavity is formed in the third connecting rod, the third telescopic spring is arranged in the cavity, the other end of the third connecting rod is fixedly connected to the third connecting seat, one end of the third inner telescopic rod enters the cavity through the hole in the third connecting rod and presses against the third telescopic spring, and the other end of the third inner telescopic rod is connected to the third wedge <NUM>.

It should be noted that the third telescopic rods are in the diameter directions of the second connecting seat.

Similarly, it may be known that the fourth brake <NUM> includes fourth telescopic rods and a fourth connecting seat, the fourth connecting seat is cylindrical and is sleeved on the outside of the second central shaft <NUM>, and the diameter of the inner hole of the fourth connecting seat is equal to the diameter of the second central shaft <NUM>, so that the fourth connecting seat can move on the second central shaft <NUM> under an action of an external force.

In the embodiment, the action of the external force that enables the fourth brake <NUM> to move relative to the second central shaft <NUM> is that an operator manually moves the fourth brake <NUM>, so that the fourth brake <NUM> can be stopped at a desired position to make the diameter of the second end shaft <NUM> be of a diameter size required for the adjustment to the horizontal state.

The fourth telescopic rods are evenly distributed on the outer circumference of the fourth connecting seat, one end of the fourth telescopic rod is connected to the fourth connecting seat, and the other end thereof is a free end, which is telescopic relative to the fixed end. To be specific, the eighth arc surface of the fourth wedge <NUM> is provided with a fourth installation hole, which is arranged at an end close to the big end of the fourth wedge <NUM>, and the free end of the fourth telescopic rod is installed in the fourth installation hole.

To be specific, the fourth telescopic rod includes a fourth telescopic spring, a fourth inner telescopic rod and a fourth connecting rod, one end of the fourth connecting rod is provided with a hole and a cavity is formed in the fourth connecting rod, the fourth telescopic spring is arranged in the cavity, the other end of the fourth connecting rod is fixedly connected to the fourth connecting seat, one end of the fourth inner telescopic rod enters the cavity through the hole in the fourth connecting rod and presses against the fourth telescopic spring, and the other end of the fourth inner telescopic rod is connected to the fourth wedge <NUM>.

In the embodiment, the third telescopic rods are automatically telescopic along with the movement of the third brake <NUM>, and the fourth telescopic rods are automatically telescopic along with the movement of the fourth brake <NUM>. Since the side surfaces of the third wedges <NUM> and the fourth wedges <NUM> are in contact with each other, the telescopic amounts of the third telescopic rods and the fourth telescopic rods can be defined under acting forces of the third wedges <NUM> and the fourth wedges <NUM>, that is, when the positions of the third brake <NUM> and the fourth brake <NUM> are fixed, the third telescopic rods and the fourth telescopic rods can maintain a specific length under actions of pressing forces of the side surfaces of the third wedges <NUM> and the fourth wedges <NUM>.

It should be noted that the fourth telescopic rods are in the diameter directions of the fourth connecting seat.

It should be noted that the external force that causes the third brake <NUM> and the fourth brake <NUM> to move relative to the second central shaft <NUM> is not limited to a manual operation, and any driving manner that can make the third brake <NUM> and the fourth brake <NUM> move relative to the second central shaft <NUM> is allowed.

In the embodiment, the third brake <NUM> controls the movement of the third wedges <NUM>, and the fourth brake <NUM> controls the movement of the fourth wedges <NUM>. When the second end shaft <NUM> is worn, which causes the diameter of the second end shaft <NUM> to decrease, under the actions of the third telescopic rods and the fourth telescopic rods, the third wedges <NUM> and the fourth wedges <NUM> move outwards in the radial direction of the second end shaft <NUM>, and the third brake <NUM> and the fourth brake <NUM> are manually moved, so that the third brake <NUM> and the fourth brake <NUM> move oppositely along the second central shaft <NUM>, the side surfaces of the third wedges <NUM> are in close contact with the side surfaces of the fourth wedges <NUM>, and the fifth arc surfaces of the third wedges <NUM> and the seventh arc surfaces of the fourth wedges <NUM> form the outer circumference of the second end shaft <NUM> having a new diameter. As shown in <FIG> is a schematic diagram of a change that the diameter of the second end shaft <NUM> is adjusted to a smaller one from the initial position, <FIG> is a schematic diagram that the diameter of the second end shaft <NUM> is in the initial state, and <FIG> is a schematic diagram of a change that the diameter of the second end shaft <NUM> is adjusted to a larger one.

It should be noted that in order to reduce manufacturing costs, the first end shaft <NUM> and the second end shaft <NUM> have the same size and structure.

It should be noted that the first wedges <NUM> and the second wedges <NUM> define a first outer surface forming the first end shaft <NUM> (composed of the first arc surfaces of the first wedges <NUM> and the third arc surfaces of the second wedges), the first outer surface has a first effective diameter, which increases or decreases in accordance with an axial movement between the first wedges <NUM> and the second wedges <NUM> (that is, the first wedges <NUM> and the second wedges <NUM> move towards each other along the first central shaft <NUM>, with the first effective diameter increasing, and the first wedges <NUM> and the second wedges <NUM> move away from each other along the first central shaft <NUM>, with the first effective diameter decreasing); the third wedges <NUM> and the fourth wedges <NUM> define a second outer surface forming the second end shaft <NUM> (composed of the fifth arc surfaces of the third wedges <NUM> and the seventh arc surfaces of the fourth wedges <NUM>), the second outer surface has a second effective diameter, which increases or decreases in accordance with an axial movement between the third wedges <NUM> and the fourth wedges <NUM> (that is, the third wedges <NUM> and the fourth wedges <NUM> move towards each other along the second central shaft <NUM>, with the second effective diameter increasing, and the third wedges <NUM> and the fourth wedges <NUM> move away from each other along the second central shaft <NUM>, with the second effective diameter decreasing).

Since the material of the roller must be an acid- and alkali-resistant material, the material of the first end shaft <NUM>, the second end shaft <NUM> and the liquid-carrying shaft <NUM> is PVDF (Poly vinylidene fluoride) or PTFE (Poly tetra fluoroethylene).

The liquid-carrying roller <NUM> in the embodiment is applied to a wet etching tank. An etching tank <NUM> comprises the bracket <NUM> and the liquid-carrying rollers <NUM>, an etching liquid <NUM> is provided in the etching tank <NUM>, a solar wafer <NUM> is arranged on the liquid-carrying rollers <NUM>, the upper surface of the solar wafer <NUM> is provided with a water film <NUM>, and liquid-carrying rollers <NUM> are connected to the bracket <NUM>. To be specific, the bracket <NUM> includes a bracket body <NUM>, which is evenly provided with installation holes <NUM>, and the first end shafts <NUM> and the second end shafts <NUM> of the liquid-carrying rollers <NUM> are arranged in the installation holes <NUM> of the bracket body <NUM> on both sides of the bracket <NUM>, respectively.

In the embodiment, when the friction between the liquid-carrying roller <NUM> and the bracket <NUM> causes wear, it is not required to replace the entire liquid-carrying roller <NUM>, and it is only required to adjust the diameters of the end shafts, which reduces the operating costs of the etching tank <NUM>. In addition, levelness of the liquid-carrying roller <NUM> may be adjusted independently.

Another specific embodiment of the invention discloses a wet etching method, the liquid-carrying roller for wet etching of Embodiment <NUM> being used, the method comprising:
Step <NUM>: The shaft ends of the liquid-carrying rollers <NUM> are adjusted to ensure that a solar wafer <NUM> is in a horizontal state when being placed on the liquid-carrying rollers <NUM>.

It should be noted that a plurality of liquid-carrying rollers <NUM> are installed in the etching tank <NUM>, and it is required to adjust all of the liquid-carrying rollers <NUM> so that the solar wafer <NUM> is in a horizontal position.

The first brake <NUM> and the second brake <NUM> are moved towards each other to make the first wedges <NUM> and the second wedges <NUM> move towards the center of the cylinder of the first end shaft <NUM>, with the diameter of the first end shaft <NUM> increasing; the third brake <NUM> and the fourth brake <NUM> are moved towards each other to make the third wedges <NUM> and the fourth wedges <NUM> move towards the center of the cylinder of the second end shaft <NUM>, with the diameter of the second end shaft <NUM> increasing;
the first brake <NUM> and the second brake <NUM> are moved away from each other to make the first wedges <NUM> and the second wedges <NUM> move away from the center of the cylinder of the first end shaft <NUM>, with the diameter of the first end shaft <NUM> decreasing; the third brake <NUM> and the fourth brake <NUM> are moved away from each other to make the third wedges <NUM> and the fourth wedges <NUM> move away from the center of the cylinder of the second end shaft <NUM>, with the diameter of the second end shaft <NUM> decreasing.

Step <NUM>: The solar wafer <NUM> is placed on the liquid-carrying rollers <NUM>, which rotate under an action of an external force (such as a motor) to brush the etching liquid <NUM> on the back of the solar wafer <NUM> for wet etching while driving the solar wafer <NUM> to move forwards.

It should be noted that since the front of the solar wafer <NUM> is provided with the water film <NUM>, damage to the front of the solar wafer <NUM> by the etching liquid <NUM> is avoided.

Claim 1:
A liquid-carrying roller for wet etching, the roller comprises a first end shaft (<NUM>), a second end shaft (<NUM>), and a liquid-carrying shaft (<NUM>), the first end shaft (<NUM>) and the second end shaft (<NUM>) being located at both ends of the liquid-carrying shaft (<NUM>), respectively, the first end shaft (<NUM>), the second end shaft (<NUM>) and the liquid-carrying shaft (<NUM>) being arranged concentrically, the roller being characterized in that the diameters of the first end shaft (<NUM>) and the second end shaft (<NUM>) are both adjustable.