The use of solder paste is growing, and the solder paste suppliers in the market have their own advantages. But the use of solder paste and its use should pay attention to the matters are not changed. The following Green Island company for you to say, solder paste use what need to pay attention to.
Solder paste display
1. The solder paste should be taken out of the cold storage or refrigerator four hours in advance before it is used, and the delivery person, time and order number shall be recorded. After reaching room temperature, turn the solder paste back to room temperature. Attention should be paid not to open in advance, resulting in low-temperature water absorption steam, and tin beads will be generated during reflow soldering; equipment should not be used to accelerate the rewarming.
2. After the solder paste is opened, it needs to be mixed and used. If the solder paste is mixed by hand, it needs to be stirred for 30 seconds. If it is manually mixed, it needs to be stirred for 5 minutes. Stir the components in the solder paste evenly to reduce the viscosity of the solder paste.
3. After the adjustment of the first printed circuit board or equipment on duty, the solder paste thickness tester shall be used to measure the solder paste printing thickness. The test points shall be selected at the top, bottom, left and right and middle of the test surface of the printed circuit board. The value shall be recorded. The solder paste thickness shall be between - 10% and + 15% of the screen board thickness.
4. If the time on the net class is too long, 30 minutes to 60 minutes, first use the stirring function of silk screen printing machine to stir and then use; for more than 60 minutes, put it into the tank first, and then open the cover to mix when using.
5. The amount of solder paste added to the screen board is determined by the amount of solder paste added to the screen board for the first time. Generally, 200-300g is added for the first time. After printing for a period of time, a little more is added appropriately to ensure that the solder paste rolls clockwise along the direction of the scraper when printing, and the thickness is about 1 / 2 to 3 / 4 of the height of the metal scraper.
6. After printing the solder paste, the paste should be pasted in a short time to avoid solvent volatilization. Generally not more than 8 hours, if more than 8 hours, need to clean out re printing.
7. After unsealing, in principle, it should be used up at one time within the same day. Solder paste exceeding the service life must not be used. Solder paste scraped back from the screen should also be sealed and refrigerated.
8. The optimum temperature of printing time is 25 ℃± 3 ℃, and the optimum temperature is 45% - 65%. If the temperature is too high, the solder paste will absorb water vapor easily, and solder beads will be produced during reflow soldering.
9. Do not put fresh solder paste and used solder paste into the same bottle. When the solder paste is to be removed from the screen, it should be replaced with another empty bottle to prevent the fresh solder paste from being polluted by the old solder paste.
Do not put new solder paste and used solder paste in the same pot. When recovering solder paste from screen, it is necessary to put it in another empty jar to avoid contamination and deterioration of new solder paste by old solder paste.
10. It is suggested that 1 / 4 of the old solder paste and 3 / 4 of the fresh solder paste should be mixed together to keep the new and old solder paste in the best condition.
11. During the production process, 100% inspection of solder paste printing quality is carried out, the main contents are whether the solder paste pattern is complete, whether the thickness is uniform, whether there is solder paste tip phenomenon.
12. Clean the mesh plate according to the process requirements after the shift.
13. After the printing experiment or printing failure, the solder paste on the printed circuit board should be thoroughly cleaned with ultrasonic cleaning equipment and dried in the air to prevent solder balls after reflow caused by residual solder paste on the board during reuse.
The above are the matters needing attention when using solder paste. The ever-changing products cannot do without caution when using. If you need to know more, please pay attention to lvzhidao solder factory.