SMT red glue is a temperature-set adhesive that is used during the SMD process to fix certain components to the board in circumstances where they might lose connection or fall off before reflow. Because of the viscosity, fluidity, wetting and other properties of the adhesive red glue will be affected by the temperature, it should be used under certain conditions. We'll discuss those today.
SMT red glue caracteristics:
Red glue is a kind of Poly dilute compounds. The difference with solder paste is that the glue will solidify after heating. After reaching the coagulation point temperature of 150 centigrade, the paste body will start change directly into a solid. SMT red glue has properties of viscosity, temperature, and wetting. According to the properties, in production the purpose of using red glue is to make the parts firmly stick on the surface of PCB and avoid falling:
1. The higher the curing temperature and the longer the curing time, the stronger the bonding strength;
2. Cure time: 100 centigrade to 120 centigrade, 60-120 seconds; high temperature curing: 150 centigrade, 90-120 seconds;
Conditions of use:
1. The SMT red glue should be kept in refrigerator or 2-8 centigrade, to prevent the impact on characteristics due to the temperature change.
2. The SMT red gum should raise the temperature at room temperature for 4 hours and should be used in the order of first in first out (FIFO).
3. For the dispensing, the rubber tube red glue should be de-foamed. For the red glue that has not been used up, it should be put back into the refrigerator for preservation. Old glue cannot be mixed with new glue.
SMT red glue process:
Printing method and steel mesh holes are determined by the type of parts, the performance of the base material, its thickness, hole size, and shape.
The trepanning process of red glue is different from that of solder paste steel mesh. The trepanning of steel mesh can be directed according to the position of patch pad. In this way, solder paste can be directly leaked on the PCB pad for further welding. But the red glue steel mesh is special. Its function is to brush the glue, paste the components and make them convenient to weld, so the trepanning is between the device welding plates.
Dispensing method: dispensing is use compressed air to put the red glue to the substrate through the special dispense head. The glue point’s size and number are controlled by time, pressure pipe diameter and other parameters. The point glue machine has flexible functions. For different components, we can use different dispensing heads and setting different parameters. The glue point’s shape and number can also be changed. We can adjust the working parameters, speed, time, air pressure and temperature to achieve good performance.
The product after red glue curing needs to do the thrust test as below:
Only when the appropriate parameters are developed and the rules between them are mastered can the high-quality SMT be obtained. As a premium provider of PCBA, we provide this service to you!