CN111864009A - A method for alignment by screen printing on the back of a double-sided PERC cell - Google Patents

Abstract

The invention discloses a method for aligning the back of a double-sided PERC battery. The method comprises the following steps: arranging a laser slotted line on a silicon wafer where an aluminum grid is prepared to be printed to form a laser slotted area; There are three laser mark points, all of which are located at the periphery of the laser slotting area. The three laser mark points are connected to form a triangle, and the center of the triangle coincides with the center of the silicon wafer; the aluminum gate and the back electrode are respectively positioned by the laser mark points. , so that the subsequently printed aluminum grid covers the laser grooved area and is connected to the later printed back electrode. The invention can realize the precise alignment of screen printing, solve the problem of detachment of the connection between the back electrode and the aluminum grid, and improve the battery performance; because the invention adopts three laser mark points, compared with the existing four laser mark points, The process time is reduced and the production efficiency is improved.

Description

A method for alignment by screen printing on the back of a double-sided PERC cell

technical field

The invention relates to solar cell technology, in particular to a method for alignment by screen printing on the back of a double-sided PERC cell.

Background technique

PERC (Passivated Emitter and Rear Cell), that is, passivated emitter and rear cell technology, on the basis of conventional solar technology, the back surface of the cell is passivated with a dielectric film, and the metal local contact is used, which greatly reduces the rate of minority carrier recombination on the back surface. , while enhancing the light reflection of the back surface. Benefiting from the presence of the backside passivation layer, the PERC cell maximizes the potential difference between the p-n junctions, which enables a more stable flow of electrons and reduces the recombination of electrons, thereby improving cell efficiency. Due to the strong compatibility of PERC cells with conventional cell production lines, low transformation and upgrade costs, and extremely high efficiency advantages, in recent years, PERC cells have replaced conventional cells and become the most commonly produced solar cells in the industry.

The double-sided PERC cell is based on the single-sided PERC cell, by changing the all-aluminum back field on the back to local aluminum grid lines, and realizing the local contact between the back aluminum grid and the silicon substrate through back laser grooving, and the back all aluminum layer. The full shading structure is adjusted to the light-receiving structure of the local aluminum grid lines. In actual use, the back of the battery can also fully absorb the reflected light in the environment, increasing the overall light absorption, thereby realizing the double-sided power generation of the battery. The key to the backside power generation is the precise alignment of the backside aluminum grid and the laser grooved area, and the backside aluminum grid should cover the laser grooved area, which puts forward higher requirements for screen printing accuracy.

Therefore, in the preparation process of PERC double-sided solar cells, laser mark points are generally set on the back of the silicon wafer, and the printing of the aluminum grid on the back is to achieve the alignment of the aluminum grid and the laser groove pattern by grabbing the laser mark points by the camera. The printing alignment of the back electrode is manually adjusted. Due to the error between the positioning of the back laser mark point and the manually adjusted back electrode positioning, the connection between the aluminum gate printed on the back of the silicon wafer and the back electrode is disconnected. It affects the performance of the battery; and 4 alignment laser mark points are often used in mass production, and each mark point needs to be engraved separately by the laser, which increases the process time and affects the equipment productivity.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for screen printing alignment on the back of a double-sided PERC cell, which is simple in process, low in cost, and can achieve precise alignment of screen printing to improve cell performance and production efficiency.

The object of the present invention is achieved through the following technical solutions: a method for aligning the back of a double-sided PERC cell, which is characterized in that it comprises the following steps:

S1. In the laser grooving process on the back of the battery, a laser grooving line is set on the silicon wafer where the aluminum grid is to be printed to form a laser grooving area;

S2. Set a laser mark point at the position where the back electrode is to be printed. There are three laser mark points, all of which are located at the periphery of the laser slotting area. The three laser mark points are connected to form a triangle, and the center of the triangle is in phase with the center of the silicon wafer. coincide;

S3, using the laser mark points to locate the aluminum grid and the back electrode respectively, so that the aluminum grid to be printed subsequently covers the laser slotted area, and is connected to the back electrode to be printed later.

The laser mark points of the present invention are three, the three laser mark points are connected to form a triangle, and the center of the triangle coincides with the center of the silicon wafer. Therefore, the three laser mark points can be used to locate the aluminum grid and the back electrode respectively, so as to achieve accurate screen printing. Alignment, solves the problem of detachment between the back electrode and the aluminum grid connection, and improves the battery performance; because the present invention adopts three laser mark points, compared with the existing four laser mark points, the process time is reduced and the production is improved. efficiency.

As a preferred embodiment of the present invention, two laser marking points are located on the same side and on the same horizontal line, and the other laser marking point is located on the other side.

Compared with the prior art, the present invention has the following remarkable effects:

(1) The present invention uses three laser mark points to locate the aluminum grid and the back electrode respectively, which can realize precise alignment of screen printing, solve the problem of detachment of the connection between the back electrode and the aluminum grid, and improve the battery performance.

(2) Since the present invention adopts three laser marking points, compared with the existing four laser marking points, the process time is reduced and the production efficiency is improved.

(3) The process of the invention is simple, the cost is low, and it is easy to realize mass production.

Description of drawings

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Fig. 1 is the structure schematic diagram that the present invention arranges laser groove area and three laser mark points on the back of silicon wafer;

FIG. 2 is a schematic structural diagram of printing an aluminum grid and a back electrode on the back of a silicon wafer according to the present invention.

Detailed ways

As shown in Figures 1 and 2, it is a method for screen printing alignment on the back of a double-sided PERC cell of the present invention, comprising the following steps:

S1. In the laser grooving process on the back of the battery, a laser grooving line 2 is set on the silicon wafer 5 at the position where the aluminum grid 3 is to be printed to form a laser grooving area;

S2. Set the laser mark point 1 at the position where the back electrode 4 is to be printed. There are three laser mark points 1, all of which are located at the periphery of the laser slotting area. The three laser mark points 1 are connected to form a triangle, and the center of the triangle and the silicon The center of the sheet 5 is coincident;

S3. Use the laser mark point 1 to position the aluminum grid 3 and the back electrode 4 respectively, so that the aluminum grid 3 to be printed subsequently covers the laser grooved area and is connected to the back electrode 4 to be printed later.

In this embodiment, the two laser marking points 1 are located on the same side and on the same horizontal line, and the other laser marking point 1 is located on the other side.

In other embodiments, the positions of the three laser mark points only need to be located at the periphery of the laser grooved area and at the position where the back electrode is to be printed, and no other requirements are required.

The embodiments of the present invention are not limited to this. According to the above-mentioned content of the present invention, according to the common technical knowledge and conventional means in the field, and without departing from the above-mentioned basic technical idea of the present invention, the present invention can also make other various forms. Modifications, substitutions or changes all fall within the scope of protection of the present invention.

Claims (2)

1. a method for screen printing alignment on the back of a double-sided PERC battery, characterized in that it may further comprise the steps: S1. In the laser grooving process on the back of the battery, a laser grooving line is set on the silicon wafer where the aluminum grid is to be printed to form a laser grooving area; S2. Set a laser mark point on the position where the back electrode is to be printed. There are three laser mark points, all of which are located at the periphery of the laser slotting area. The three laser mark points are connected to form a triangle, and the center of the triangle is the same as that of the silicon wafer. the center coincides; S3, using the laser mark points to locate the aluminum grid and the back electrode respectively, so that the aluminum grid to be printed subsequently covers the laser slotted area, and is connected to the back electrode to be printed later. 2. The method for alignment by screen printing on the back of a double-sided PERC cell according to claim 1, wherein the two laser mark points are located on the same side and on the same horizontal line, and the other laser mark point is located on the other side. side.

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