(1) Count the types of defects in the welding production process.
Common problems in the lamination production process include bubbles, debris, broken corners and nicks on the cell, cracks in the cell, foreign matter (non-hair and garbage) on the cell in the module, hair and garbage in the module, and busbar occurrence Deformation, bumps (bumps and bumps) appear on the back of the component, and the cell is shifted, which exceeds the range of process requirements.
① Air bubbles. Improper setting of lamination parameters, contamination of packaging materials and other reasons will cause the appearance of bubbles in photovoltaic modules after lamination. The conditions include: full-board bubbles between the cells and gaps, partial bubbles in the middle of the module, and bubbles on the tin-coated soldering tape. , The air bubbles on the interconnection belt and the air bubbles on the insulation position, etc.
Case 1: Full-plate bubbles between the cell and the gap, as shown in Figure 1.
Cause: The laminator is not vacuumed, which is improper operation method of the laminator, the cover is not closed in place or the vacuum pump is not turned on, or the laminator itself is faulty.
Case 2: Part of the bubble in the middle of the component, as shown in Figure 2.
Cause: This bubble is caused by late vacuuming.
Case 3: Air bubbles on the tin-coated tape, as shown in Figure 3.
Cause: Too much humidity in EVA is the main reason.
Case 4: Bubbles on the interconnection belt, as shown in Figure 4.
Cause: The bubbles on the interconnection tin-coated tape are related to the amount of flux and the cleaning of the mold when welding the “L”-shaped tin-coated soldering tape.
② Displacement. The displacement defects of photovoltaic modules during the lamination process include the overall displacement of all battery strings, the displacement of the gap between different strings and the gap between the same string and the gap.
Case 1: All the battery strings of the module are displaced as a whole, resulting in the distance between the battery slice and the edge of the glass being less than 10mm, as shown in Figure 5.
Cause: The size of the board was not completely made according to the requirements, or the deviation was caused during the turnover process. Laminating will not cause overall deviation.
Case 2: Different strings-the gap between strings is shifted, resulting in the gap between different battery strings being less than 1mm, as shown in Figure 6.
Reasons: no fixed adhesive tape is attached; EVA has high fluidity when melting, the shrinkage rate is too large, the airbag pressure time is too early, and the vacuum pump pumping speed is too fast.
Case 3: The gap between the cells in the same string is shifted, resulting in the gap between the cells in the same cell string being less than 1 mm, as shown in Figure 7.
Cause: The gap during stringing is too small. It may be that the stringing template is damaged or the battery slices do not fully support the pillars on both sides during operation; the large size of the incoming battery slices also causes the gap between the slices to be too small.
③ Fragments. The occurrence of debris during the lamination process includes debris at the edge of the module, debris at the lead-out line of the module, and debris at other locations.
Case 1: Fragments at the edge of the component, as shown in Figure 8.
Cause: Most of the fragments near the edge of the module are the dark cracks caused by the previous process in the production or the dark cracks caused by the incoming materials; most of the fragments at the corners of the module are caused by the human operation of the lamination group.
Case 2: Fragments at the component lead wires, as shown in Figure 9.
Cause: The main reason for the debris at the lead-out line is that the airbag inflates and presses down for too short time, and the impact force on the lead-out line of the module is too large, causing fragments; the lead-out line is too close to the lead-out line on the battery, and the airbag is pressed down Excessive pressure is placed on the cell at the time, causing fragmentation.
Case 3: Fragments in other locations, as shown in Figure 10.
Cause: The fragments of the cell in the middle of the module are generally fragments before lamination. The dark cracks caused by human operation and the turnover process are most likely to cause fragments.
(2) Use analysis methods such as Pareto chart and fishbone chart in the quality management tool to make corresponding analysis charts for the number of various defects counted, as shown in Table 1.
| Total number of defects | Types of defects | quantity | percentage/% | Cumulative percentage/% |
| 14 | Broken corners of battery slices | 8 | 57.14 | 57.14 |
| 14 | Cell fragments | 3 | 21.43 | 78.57 |
| 14 | Cell gap | 1 | 7.14 | 85.71 |
| 14 | Cell cracked | 1 | 7.14 | 92.86 |
| 14 | Foreign matter on the battery | 1 | 7.14 | 100.00 |
| 14 | other | 0 | 0.00 | 100.00 |
(3) Analyze and list the reasons for each defect from the chart.
(4) Through the analysis of various reasons, find a reasonable and scientific solution for one reason. It can be analyzed from the five elements of the product production process, namely human, machine, material, method, and environment.
(5) Formulate reasonable and scientific measures and implement them vigorously.
①Control the amount of EVA used every day, and let each employee understand the daily production tasks.
② Make the cut on the same day and use it up on the same day.
③The materials are determined by the manufacturer, so try to choose better materials with stable quality.
④Adjust the lamination process parameters to make the vacuum time appropriate.
⑤Increase the lamination pressure. It can be adjusted by the lamination time, or it can be achieved by laying a layer of high-temperature cloth.
⑥Push a high-temperature cloth to heat the components evenly (the maximum temperature difference is less than 4℃).
⑦According to the parameters provided by the manufacturer, determine the total time of lamination to avoid too long time.
⑧ 6S management should be paid attention to, especially in the process of lamination, try to avoid foreign objects falling.
⑨Employees should strictly follow the rules of each gesture and each action in the process documents, and resolutely do not touch the components within the time.