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SMT patch of red glue basic knowledge

2020-4-13 Frome:Dongguan Huaxian Electronic Technology Co., Ltd.
Core tip: SMT patch red glue is a kind of poly-dilute compound, which is different from solder paste in that it solidifies after heating, and its freezing point temperature is 150 ℃, at this time, the red glue begins to change from paste to solid directly. 
SMT patch red glue has viscosity fluidity, temperature characteristics, wetting characteristics and the like. According to this characteristic of red plastic, in the production, the purpose of using red glue is to make the parts firmly adhere to the surface of the PCB to prevent it from falling. 
Used on printer or dispenser:
1. In order to maintain the quality of the patch adhesive, please store it in the refrigerator (5±3 °C);
 2, After taking out from the refrigerator, should be placed at room temperature for 2 to 3 hours;
3. you can use toluene or ethyl acetate to clean the dispensing those.
① a more stable dispensing amount can be obtained by adding a back plug into the dispensing tube            
② the recommended dispensing temperature is 30-35 ℃           
③ please use the special red glue dispenser to separate the tubes to prevent air bubbles from mixing in the red glue
Note: after the red glue is removed from the cold storage environment, it can not be opened for use before reaching the room temperature. In order to avoid contamination of the original product, any used red glue shall not be returned to the original packaging.
 1) Printing method: the steel mesh hole shall be determined according to the type of the part and the performance of the base material, its thickness, the size and shape of the hole. Its advantages are high speed and efficiency. 
2) Dispensing mode: dispensing is to use compressed air to spot red glue through the special dispensing head to the base plate. The size and number are controlled by time and pressure pipe diameter and other parameters. The dispensing machine has flexible functions. For different parts, we can use different dispensing heads, set parameters to change, and also can change the shape and number of glue points to achieve the effect, with the advantages of convenience, flexibility and stability. The disadvantage is easy to have drawing and bubble. We can adjust the operation parameters, speed, time, air pressure and temperature to minimize these shortcomings.
3) The needle rotation mode is to dip a special needle film into the shallow glue plate and each needle has a glue point. When the glue point contacts the substrate, it will break away from the needle. The glue amount can be changed by the shape and diameter of the needle. 
Curing temperature 100 ℃ 120 ℃ 150 ℃ curing time 5 minutes 150 seconds 60 seconds. 
Note for typical curing conditions: 
1. The higher the curing temperature and the longer the curing time, the stronger the bonding strength.
2. As the temperature of the glue will vary with the size of the substrate parts and the mounting position, we suggest to find the most suitable hardening conditions.
Storage of red glue: it can be stored for 7 days at room temperature, more than 6 months at less than 5 ℃, and more than 30 days at 5-25 ℃. Due to the influence of temperature on SMT red glue with its own viscosity, fluidity, wettability and other characteristics, SMT red glue should have certain use conditions and standardized management of SMT red adhesive.
1) Red glue shall have a specific serial number, which shall be numbered according to the quantity, date and type of materials. 
2) The red glue should be stored in the refrigerator at 2-8 ℃ to prevent the temperature change from affecting the properties.
3) The temperature of red glue shall be returned at room temperature for 4 hours, and it shall be used in the order of first in first out.
4) For dispensing operation, the red glue of the hose shall be defoaming, and the red glue that is not used up at one time shall be put back to the refrigerator for preservation, and the old glue and the new glue shall not be mixed.
5) To accurately fill in the temperature return record form, the temperature return person and the temperature return time, the user needs to confirm the completion of the temperature return before using. In general, red glue should not be used when it is out of date.

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