1、 Red gum
Red glue is a polyolefin compound, which is easy to solidify after heating. When its temperature reaches the freezing point of 150 ℃, red glue begins to change from paste to solid. Using this characteristic, patch components can be fixed by dispensing or printing, and circuit board components can be heated and solidified by oven or reflow soldering.
The components on the circuit board, especially the circuit board with double-sided mounting, are fixed with patch red glue during wave soldering, so that the small patch components on the back will not fall into the tin furnace. Red glue has several characteristics:
① Stable adhesion strength can be obtained for various chip components;
② It has the viscosity and shake property suitable for screen printing, and the glue amount is stable without missing brush or tower edge;
③ It has good preservation stability;
④ It has high adhesion strength, which can avoid component deviation during high-speed patch.
Main function: the main function of red glue is to fix the circuit board patch components, mainly for bonding, or used together with solder paste as reinforcement and fixation.
2、 Yellow gum
The yellow glue used in the circuit board is a water binder. It has a pungent odor. It is a soft self adhesive gel. It has excellent insulation, moisture-proof, shockproof and thermal conductivity, enabling electronic components to operate safely under harsh conditions.
It is easy to cure, and the curing speed is related to the ambient temperature, humidity and wind speed: the higher the temperature, the lower the humidity, the greater the wind speed, the faster the curing speed, and vice versa. When the coated parts are placed in the air, there will be slow scaling. Note that the operation should be completed before the surface scaling.