CN102810603A - Screen Printing Overprinting Alignment Detection Method for Solar Cell Electrodes - Google Patents

Abstract

The invention relates to a screen printing overprint alignment detection method for electrodes of solar cells. The method comprises the following steps: a. The manufacture of the battery sheet, forming a front layer pattern with a lower square resistance resistance value on a silicon substrate, and forming at least one detection pattern with a lower square resistance value outside the outline range of the front layer pattern , and then overprint the front electrode within the outline of the front layer pattern by screen printing method; b. screen printing overprint alignment detection, apply a voltage between the front electrode and the silicon wafer substrate, and observe the detection pattern on the infrared photo Brightness, to judge whether the printing of the front electrode is offset. The invention can monitor the position deviation of the overprinted front electrode, and has high detection efficiency and low detection cost.

Description

Screen Printing Overprinting Alignment Detection Method for Solar Cell Electrodes

technical field

The invention belongs to the manufacturing technology of crystalline silicon solar cells, in particular to a screen printing overprint alignment detection method for electrodes of solar cells used for detecting the alignment quality of electrodes printed by screen printing on solar cells.

Background technique

In crystalline silicon solar cells, the front layer pattern is usually formed on the silicon wafer substrate by mask method or other methods. The front side electrodes are overprinted within the layer pattern outline. If the printing is offset, it will affect the final quality of the product. And since the pattern of the front layer is usually not visible, it brings difficulty to monitor the printing offset.

There are currently two methods for monitoring printing offset: one is to use a silicon wafer printed with the same pattern, which is clearly visible on the silicon wafer, and measure the centerline of the two patterns after printing the front electrode pattern on it deviation, as a method of monitoring printing offset, this method is cumbersome to operate and increases manufacturing costs; the other is to use an online front-layer pattern recognition system, which can detect the front-layer pattern and calculate the pattern According to the relative position of the silicon wafer, the system automatically calibrates the coordinates of the printing head according to the relative position, so that the subsequent graphics can be accurately overprinted on the front layer pattern. The system needs to adopt an expensive graphic recognition system, which is relatively expensive and generally has relatively few configurations.

Contents of the invention

The technical problem to be solved by the present invention is to provide a screen printing overprint alignment detection method for electrodes of solar cells that can monitor the offset of the overprinted front electrode, has high detection efficiency and low detection cost.

The screen printing overprint alignment detection method of the solar cell electrode of the present invention comprises the following steps:

a. For the manufacture of battery sheets, a front layer pattern with a lower square resistance value is formed on a silicon wafer substrate, and at least one detection pattern with a lower square resistance value is formed outside the outline range of the front layer pattern, and then screen printing The method overprints the front electrode within the range of the front layer pattern outline;

b. Screen printing overprint alignment detection, apply a voltage between the front electrode and the silicon wafer substrate, observe the brightness of the detection pattern on the infrared photo, and judge whether the printing of the front electrode is offset; if the brightness of the detection pattern is higher than before If the other areas other than the layer pattern are high, it is judged that the electrode printing has shifted; if the brightness of the detected pattern is not significantly different from that of the other areas other than the previous layer pattern, it is judged that the electrode printing has not shifted.

Preferably, a plurality of detection patterns are provided.

Preferably, the plurality of detection patterns are divided into at least one group, and the plurality of detection patterns in the same group are based on a segment of the straight contour line of the previous layer pattern, and the shortest distance between each detection pattern in a group and the contour line as the reference The spacing is gradually changed and arranged; according to the number of detection patterns with higher brightness, the offset of the front electrode is judged.

The present invention forms a low-resistance detection pattern on the silicon chip. When the front electrode printing deviates beyond the allowable value, it will cross the front layer pattern outline and contact the detection pattern. At this time, the front layer pattern can be connected to the silicon chip. The method of detecting the voltage between the substrates makes it clearly displayed, and has the advantages of convenient operation, high detection efficiency, and low manufacturing and detection costs. The principle is: under the forward bias of the pn junction, the potential barrier region and the diffusion region will inject minority carriers, and these unbalanced minority carriers will continuously recombine with the majority carriers to emit light. Experiments have proved that the logarithm of the electroluminescence intensity of crystalline silicon solar cells is directly proportional to the forward current density. When the forward voltage is fixed, if the local resistivity of the battery sheet is different, the current density of this part is also different. If different areas of the same cell are diffused to produce different sheet resistances, and then a forward voltage is applied to the surface of the cell, the electroluminescence intensity is relatively large where the diffusion sheet resistance is small (low resistivity, high current density), and on the contrary Where the diffusion sheet resistance is large (high resistivity, low current density) the electroluminescence intensity is weak. In addition, by setting a plurality of detection patterns with different distances from the contour line of the previous pattern, the offset of electrode printing can be intuitively indicated, which facilitates the adjustment of the system.

Description of drawings

Fig. 1 is a schematic diagram of the structure of a cell obtained in an embodiment of the present invention;

Fig. 2 is a schematic diagram of a partially enlarged structure of A in Fig. 1;

Fig. 3 is a schematic diagram of a partial enlarged structure obtained by the embodiment of the present invention when the electrode printing of the battery sheet is offset.

Detailed ways

The screen printing overprinting alignment detection method of solar cell electrode in the embodiment of the present invention comprises the following steps:

a. The manufacture of the battery sheet, on the silicon wafer substrate 1, form a front layer pattern 2 with a lower square resistance resistance value, form a plurality of detection patterns 4 with a lower square resistance resistance value outside the outline range of the front layer pattern, and then pass The screen printing method overprints the front electrode 3 within the contour range of the front layer pattern 2; multiple detection patterns 4 are divided into multiple groups, and are distributed near the four corners of the silicon wafer (it can also be distributed on the silicon wafer according to the requirements of alignment detection). elsewhere in the slice). A plurality of detection patterns 4 in the same group are based on a segment of the straight contour line of the previous layer pattern 2 , and the shortest distance between each detection pattern 4 in a group and the contour line as a reference is gradually changed.

b. Screen printing overprint alignment detection, apply a voltage between the front electrode 3 and the silicon wafer substrate 1, observe the brightness of the detection pattern 4 on the infrared photo, and judge whether the printing of the front electrode is offset; if the detection pattern 4 If the brightness of the detection pattern 4 is higher than that of other areas other than the front pattern 2, then it is judged that the electrode printing has shifted; ; According to the number of detection patterns with brighter brightness, determine the offset of the front electrode.

The principle is:

After a voltage V is applied between the front electrode 3 and the silicon wafer substrate 1, because the sheet resistance in the front layer pattern 2 is low, the current density in this area is relatively large, so the corresponding electroluminescent intensity is relatively large. On the photo, this area is brighter than other areas;

If the printed front electrode is not offset (as shown in Figure 2), although the detection pattern has a lower sheet resistance at this time, because the front electrode 3 and the detection pattern 4 do not overlap, the current density is low. In the infrared photo , there is no obvious difference between this area and the area other than the previous layer pattern 2;

If the printed front electrode is offset (as shown in Figure 3), the front electrode 3 and the detection pattern 4 overlap at this time, and if a voltage V is applied between the front electrode 3 and the silicon wafer substrate 1, then in the infrared In the photo, you can see that the detection pattern 4 and the front layer pattern 2 are relatively bright. Among the multiple detection patterns 4 in the same group, since the distance between each detection pattern 4 and the outline of the previous layer pattern is different, the amount of displacement of the front electrode 3 can be determined according to the number of detection patterns with higher brightness.

Claims (3)

1. the silk screen printing chromatography aim detecting method of a solar cell plate electrode is characterized in that: may further comprise the steps

A. the manufacturing of battery sheet; On silicon chip substrate 1, form the lower preceding layer pattern 2 of square resistance resistance; Outside anterior layer pattern contour scope, form the lower check pattern of at least one square resistance resistance 4, then through method for printing screen chromatography front electrode 3 in preceding layer pattern 2 profile scopes;

B. silk screen printing chromatography aim detecting applies a voltage between front electrode 3 and silicon chip substrate 1, on infrared photograph, observes the brightness of check pattern 4, judges whether the front electrode printing squints; If other zones before the brightness ratio of check pattern 4 beyond the layer pattern 2 are high, judge that then skew has taken place in the electrode printing; Do not have significant difference if the brightness of check pattern 4 is compared with other zones beyond the preceding layer pattern 2, judge that then the electrode printing do not squint.

2. the silk screen printing chromatography aim detecting method of solar cell plate electrode according to claim 1 is characterized in that: a plurality of check pattern 4 are set.

3. the silk screen printing chromatography aim detecting method of solar cell plate electrode according to claim 2; It is characterized in that: a plurality of check pattern 4 are divided at least one group; One section straight line outline line of layer patterns 2 is a benchmark before a plurality of check pattern 4 in same group, and each check pattern 4 in a group and this are as the arrangement that gradually changes of the shortest spacing between the outline line of benchmark; During silk screen printing chromatography aim detecting,, judge the side-play amount of front electrode 3 according to the quantity of brightness higher detection pattern 4.

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