PCBA Tech - SMT patch workshop solder paste management system

Purpose: to ensure the standardization of the use and printing of SMT solder paste, provide direct and clear guidance for SMT, and achieve proper storage and correct use of solder paste. Avoid damage to the original characteristics of the solder paste due to improper operation during storage and use, and adverse effects on SMT production.

SMT patch workshop solder paste management system

1. Storage of solder paste

1.1 The brand and model of solder paste must be certified by the relevant department.

1.2 When purchasing solder paste, fill in the purchase date, expiration date, and serial number in the "Solder Paste Entry and Exit Registration Form"; distinguish different batches to ensure the smooth implementation of "first in, first out". The "Solder Paste Entry and Exit Registration Form" is handled by a dedicated person arranged by the warehouse.

1.3 The warehouse and production workshop are responsible for monitoring the expiration date of the solder paste. When the expiration date is less than or equal to one month, an early warning shall be given; at the same time, the minimum inventory shall be monitored. When the solder paste is lower than the inventory, the purchase shall be submitted.

1.4 The warehouse and production are responsible for monitoring the temperature of the refrigerator every day, and make a record. See the form "Refrigerator Temperature Recording Sheet". If there is any abnormality, seek equipment maintenance personnel to deal with it in time.

1.5 When purchasing lead-free solder paste, it should be strictly distinguished, and ROSH should be marked. It is best to have a refrigerator dedicated to lead-free solder paste, and try not to put it in the same refrigerator as the lead-free solder paste.

1.6 The shelf life of solder paste under the conditions of 1-10 degrees from the production date is 6 months without washing and 3 months with water. For details, please refer to the label of each type of solder paste bottle; disposable solder paste can only be stored for one week at room temperature Time, wash in water for 3 days; open the lid and the unused solder paste is valid for 2 days (washed for 1 day); the solder paste used on the stencil is valid for 12 hours (washed for 6 hours).

1.7 The solder paste should be stored in a refrigerator at 1-10 degrees Celsius, and a thermometer should be placed in an obvious place in the refrigerator (the thermometer is calibrated as required). Certainly.

1.8 If there is solder paste and red glue in the refrigerator, the time for opening the door should not exceed 20 seconds when picking and storing the solder paste red glue; for example, when storing the solder paste red glue in large quantities, the total time should not exceed 15 minutes. If the refrigerator is opened for 15 minutes, the door of the refrigerator cannot be opened within half 30 minutes.

2. Distribution and receiving of solder paste

2.1 The distribution of solder paste should follow the principle of first-in, first-out; the warehouse should give priority to the first-in or first-due solder paste according to the date of the solder paste.

2.2 The warehouse distributes solder paste according to the production plan. In order to avoid the waste of raw materials, it can be distributed in round numbers each time, for example: 10 bottles and 20 bottles.

2.3 The solder paste collected in the production workshop shall be stored in time as required.

3. The use of solder paste

3.1 When using solder paste, the workshop environment temperature should be controlled at 25±3°C, and the relative humidity should be controlled at 35% to 75%. If this range is exceeded, feedback to the engineer for handling.

3.2 Before using solder paste, you should carefully read the "Solder Paste Control Label" and confirm the temperature recovery time and the expiry date of the solder paste (confirmed by Quality Assurance). After confirmation, fill in the opening time and use on the "Solder Paste Control Label" Time, the unused solder paste after the outer cover is opened, should be covered with the inner cover. Push the inner cover until it is close to the surface of the solder paste, squeeze out the air inside, and then tighten the outer cover. The solder paste after the above treatment can be stored in the environment of the production site. In principle, the solder paste after opening is used up within 24 hours, and the engineer can determine whether it can continue to be used if it exceeds 24 hours.

3.3 First use the used solder paste and the solder paste with an earlier production date; the production workshop is equipped with a “solder paste standby area”, and the production line is placed to return the solder paste to be used. The production line uses this part of the solder paste first; the operator opens the solder After the paste bottle is capped, observe the appearance of the solder paste and find the phenomenon of agglomeration and dry skin, and report it to the process engineer for processing. The used solder paste should not be mixed with the unused solder paste when it is recycled for the next use. It should be packed separately in an empty bottle.

3.4 Each time before adding solder paste, the solder paste must be stirred evenly before it can be used. The manual stirring speed is 2-3 seconds, 1 revolution, and the duration is 2 minutes to 5 minutes. The equipment stirring time is 3 minutes to make it into a cone flow. Matter.

3.5 Solder paste that is not in use cannot be left on site to avoid confusion.

3.6 When the SMT production line is in continuous production for a week, the operator cleans the solder paste once a week. The cleaning time is the last shift of the week, that is, when off work, the last shift will recover all the solder paste on the steel grid, which is confirmed by the project. Can you continue to use it?

3.7 When adding solder paste, a "small amount of times" method should be adopted, and the diameter of the solder paste column is about 10-15mm. After adding, clean the mixing knife in time and place it in the designated position of the solder paste bottle and the mixing knife.

3.8 The service life of the solder paste added to the SMT stencil is 12 hours, and the unused solder paste period is 48 hours after opening the lid. The solder paste recovered by the SMT stencil should be stored in a new solder paste bottle to avoid the same as the unused solder paste. Put it in a bottle. The service life of the recycled solder paste is 24 hours from the last time it was used when the cap was opened. After the expiration date, the project will confirm whether to apply for scrapping.

3.9 The remaining solder paste should cover the inner cover, push the inner cover down to touch the solder paste surface, squeeze out the air between the inner cover and the solder paste, and then tighten the outer cover. If you do not continue to use it, put it back in the refrigerator for storage, and seal the gap in the bottle mouth with tape before putting it back in the refrigerator for storage.

3.10 When there is a mixture of fresh and old solder paste, the configuration method is: mix 1/4 of the old solder paste and 3/4 of the fresh solder paste evenly to keep the new and old solder pastes mixed together All in their best condition.