PERC Battery EL Light and Dark Film Analysis (Practical Edition, Recommended Collection)
Cutting-edge instructions Light and dark films
At present, gallium-doped wafers have been popularized, but the light and dark of monocrystalline PERC cells EL is still a problem in the industry, and the battery end is basically unable to be carded, and the component end is often accompanied by many repairs, which seriously affects its profits. Through the many cases I have encountered, the editor has sorted out the following abnormal cases of light and dark films through the 5M1E analysis method. Now let's analyze the specific causes and solutions of light and dark films one by one, welcome to discuss.
1. Light and shade between films:
1.1 String type light and dark
1.2 Dispersion slight light type light and dark
1.3 Dispersion severity type light and dark
1.4 Light and dark on both sides
1.5 slice checkerboard light and dark
2. Light and shade in the film:
2.1 Light and dark in the welded type sheet
2.2 Black edge 1 of parallel main gate (EL measurable)
2.3 Black edge 2 of parallel main gate (EL undetectable)
2.4 Black edge 3 of parallel main gate (EL undetectable)
2.5 Black edge 4 of parallel main gate (EL undetectable)
2.6 Black border of the vertical main grid
1.1 String of light and shade (as shown below)
Cause analysis: This kind of light and dark is more concentrated, generally for the whole package of the cell factory or the efficiency of the component factory, generally concentrated in the case of tangential lines;
Solution: The battery end checks the internal part or offline packaging, and the component side specifications the feeding requirements in the same gear.
1.2 Dispersed type slight light light and dark (as shown below)
Cause analysis: There are two reasons for this kind of light and dark, one is efficiency mixing, and the other is that the resistivity of the corresponding silicon wafer is low or not concentrated;
The efficiency mixing is mainly caused by the leakage of the manual release of the box at the battery end; The abnormal efficiency sorting equipment at the battery end leads to mixing in the Bin box; Personnel at the component end return to repair and pick up the wrong cell;
Low resistivity or non-concentration is mainly verified by experiments, the lower the resistivity, the more obvious the difference between light and dark (as shown in the figure on the right);
Improvement measures: strengthen the training of personnel to take the piece at the component end of the battery end, check whether the battery equipment is abnormal, and card control the resistivity of incoming materials.
1.3 Dispersed severe light and dark (as shown below)
Cause analysis: this abnormal difference in light and dark is large, no failure short circuit, mainly suspected component end dicing abnormality (further investigation is required); Secondary suspicion that the battery end is artificially mixed with abnormal pieces such as grade B;
Improvement measures: The module end and battery side need further analysis and verification.
1.4 Light and dark on both sides
Cause analysis: battery lap breakdown short circuit or battery cut damage failure (EL impressed current flow direction is transmitted according to the place where the resistance is small, left and right are parallel circuits, the lap breakdown of the battery short circuit or damage, resulting in the failure of the battery, the resistance value is reduced, the size of the resistance on both sides is different, and the small area of the resistance value is preferred, resulting in the difference between light and dark on the left and right sides);
Solution: Replace the battery in the blackened area;
Note: The blackened battery observes whether the cutting is damaged or whether the welding tape at the corresponding position is lapped and short-circuited;
Countermeasures: If the welding strip is overlapped, adjust the welder clamp, replace or adjust the corresponding parameters; Adjust the corresponding dicing parameters, control the slicing depth and heat affected zone for cutting damage.
1.5 Slice checkerboard light and dark
Cause analysis:
The mixing of components is packed, and the 2-piece state appears in the scribing integrated machine, and the 1-piece state appears in the offline dicing machine; (The offline dicing machine feeds on 2 sides, and the effect of cross-release on the left and right sides is imaged as Figure 1; The whole piece of feeding on both sides of the scribing welding inte, the effect of cutting the whole piece is Figure 2); This exception must be an approximate number of the entire packet.
Cutting damage (non-destructive cutting is not popular, cutting damage is inevitable, when the cutting or heat-affected area seriously exceeds the standard and causes battery damage, this abnormality will occur and will occur regularly)
Workaround:
Mixing: Figure 1 determines that the module cutting is abnormal, and Figure 2 checks the internal part of the file or offline piece packaging, and the component end specifications the feeding requirements of the same gear;
Cutting damage: corresponding adjustment of cutting parameters, two-dimensional observation of dicing effect; Or replace the non-destructive dicing machine.
Note: The number of abnormal batteries produced by the mixing must be similar to the number of whole packs.
2.1 Welded type sheet light and dark
Cause analysis: the abnormal downtime of the stringer welding machine is long, the temperature of the light box drops, and it belongs to the odd or even pieces caused by low temperature;
Improvement measures: After the welding machine is stagnant for a long time, preheat and heat up to the temperature standard before welding.
2.2 Black edge 1 of the parallel main gate (as shown in the figure below, monolithic EL can be measured)
Cause analysis: abnormal passivation of the back of the battery end;
Improvement measures: increase the wet weight of the back aluminum.
2.3 Black edge 2 of the parallel main gate (as shown in the figure below, monolithic EL cannot be measured)
Cause analysis: the offset between the back aluminum and the back silver lap;
Improvement measures: monitor the offset of the back aluminum and the back pole; Add centipede feet to the design; Increase the back electrode width.
2.4 Black edge 3 of the parallel main gate (as shown in the figure below, EL cannot measure)
Cause analysis: the black edge of the battery repair, the front overprint in the dark place is poor, and the overprint in the bright place is normal; Take the front overprinting bad verification, there is indeed light and dark;
Improvement measures: front overprint card control, lap < 50% immediate adjustment.
2.5 Black edge 4 of the parallel main gate (as shown in the figure below, EL cannot measure)
Cause analysis: The temperature difference between the inside and outside of the sintering furnace is large, resulting in abnormal process matching, and the outer high temperature burning leads to the darkening of the half side
Improvement measures: the equipment side is improved, and the temperature difference between inside and outside is controlled within 10 °C.
2.6 The black edge of the vertical main grid
Cause analysis: drawing design problems (caused by too long reservation of the harpoon tail);
Improvement action: Modify the corresponding design drawings.
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other
There are many causes of EL light and dark, in addition to the above cases, there are also cases related to the over-distribution of opening pressure in the same gear, component infrared string welding attenuation, etc., and there are cases related to passivation in the light and shade of the chip, such as ALD watermarks, Maya head seals, etc., welcome to actively discuss.