Ⅱ. Performance testing of tinned solder tape
The performance test items of tinned solder tape are shown in Table 1.
| Test items | Inspection content | Detection method (use tools) |
| Package | Whether the packaging is intact; confirm the manufacturer, specifications and shelf life, the shelf life of tinned solder tape is 6 months | Visual inspection |
| Exterior | Whether there are oxidized black spots, uneven tin layer, distortion, edge burrs and other undesirable phenomena on the surface of the tin-coated soldering strip | Visual inspection |
| size | Compared with the geometric dimensions provided by the supplier, the width error is ±0.12mm, and the thickness error is ±O.02mm | Vernier caliper, spiral micrometer |
| Solderability | Use 320°C ~ 350°C for normal soldering. After soldering, a uniform solder layer on the main grid of the solar cell is qualified. | Electric soldering iron, flux |
| Breakability | Take 10 tin-coated solder strips with the same length and specifications from the same batch, and bend them 180° in one direction, and the number of breaks should not be less than 7 | / |
| Serpentine curvature | Pull the tinned soldering tape out to a length of 1m, and the side is close to the ruler, and the maximum distance between the side and the ruler should be less than 1. 5mm | ruler |
| Resistivity | Intercept a sample of Im-long tinned soldering strip to be tested: measure its resistance value with a DC resistance tester | DC resistance tester |
| Tensile strength and elongation | Cut a certain length of the tin-coated solder strip sample to be tested, and measure its tensile strength and elongation with a universal testing machine | Universal testing machine |
⒈Solderability
(1) Test method:
①First use the temperature test to calibrate the grid iron head to the set welding temperature, and then take a certain number of cells, and use the sample welding tape to weld by skilled workers.
②General soldering conditions: chlorine-free and no-clean flux, soldering temperature is 320°C-350°C, soldering time is 2-3S, for reference only.
(2) Requirements:
① Welding condition: Lifting action is performed at a 45° bevel to ensure that it will not fall off.
② Fragmentation situation: control the fragmentation rate within the scope of enterprise standards.
③Ease of operation (solder melting speed): Ensure that the welding speed is 3s/bar.
④Meet use requirements.
⒉Resistivity (ρ)
(1) Test method:
①Turn on the DC resistance tester for preheating half an hour in advance.
②Take a 1m long sample of the tin-coated soldering strip to be tested.
③Place the above sample on a clean insulating plate.
④Adjust the DC resistance tester to the gear for testing resistivity.
⑤ Use the two clamps of the DC resistance tester to clamp the two ends of the sample to be tested, and the resistance value can be displayed on the display of the tester.
(2) Requirements: ρ≤0.0258Ω·mm2/m.
⒊Elongation
(1) Test method: universal testing machine.
①Cut a certain length of the tin-coated soldering tape sample to be tested, record the initial length L1 and enter it into the corresponding space of the computer test software of the tensile testing machine.
②Clamp the two ends of the above sample with the clamp on the universal testing machine.
③Turn on the universal testing machine and start to stretch the sample to be tested until it breaks.
④The elongation and tensile strength of the test sample can be read from the universal testing machine.
(2) Requirements: The elongation is not less than 15%.
⒋Tensile strength
(1) Test method: tensile testing machine (universal testing machine).
The method is the same as above.
(2) Requirements: The tensile strength is not less than 200MPa.
⒌Salt spray corrosion test
(1) Test method:
① Weld 1 or 2 cells on the sample of tin-coated solder tape to be tested.
②Laminate it in the order of “glass EVA/cell sheet/EVA back film”, and make small samples (small size) under a certain lamination curing process.
③Place the above samples in the salt spray test box and open the test box.
④Take out the sample of the welding strip to be tested after 1000h of continuous testing.
(2) Requirements: There is no oxidation, corrosion or stain on the surface of the sample to be tested.
⒍Damp heat aging test
(1) Test method:
① Weld 1 or 2 cells on the sample of tin-coated solder tape to be tested.
②Laminate it in the order of “glass EV/cell/EV input/back film”, and make small samples (small size) under a certain lamination curing process.
③Put the above small sample into the damp heat aging box, take it out after 1000h under the condition of 85°C and 85% RH, and observe the condition of the sample with naked eyes.
(2) Requirements:
① The welding strip itself has no oxidation, yellowing, and blackening.
②The EVA in the vicinity of the ribbon has no yellowing or falling off.
Ⅱ. Key points for storage and use of tin-coated soldering tape
(1) Keep away from light, heat, and moisture. The product should not be bent and the package damaged during storage and transportation.
(2) Best storage conditions: constant temperature (15°C ~25°C), constant humidity (<60%), sealed with cotton cloth or stretch film.
(3) Store in a dry, non-corrosive gas room. The storage time for complete packaging is half a year, and the storage time for loose packaging is 3 months.
