Surface mount technology requirement for adhesive glue

In order to ensure the reliability of surface assembly, the adhesive glue should meet the following requirements.

1. The service life at normal temperature should be long.

2. Suitable viscosity. The viscosity of the adhesive glue should meet the requirements of different applying adhesive glue methods and temperature, different equipment, and should not be drawn when the glue drops; it can ensure sufficient height after coating without forming too large rubber bottom; After the curing, the glue droplets should not flow, so as not to flow to the welding part, affecting the welding quality.

3. Fast curing. The adhesive glue should be cured at the low temperature as possible. This avoids PCB warpage and component damage, as well as pad oxidation.

4. The bonding strength is appropriate. The adhesive glue should be able to effectively fix the chip components before soldering, and it should be convenient to replace the unqualified components during maintenance. The shear strength of the adhesive glue is usually 6~10MPa.

5. Others. There should be no gas precipitation after curing and welding; it should be compatible with the chemical in the subsequent process without chemical reaction, without disturbing the circuit function; colored, easy to check, the typical color of SMT adhesive glue is red or orange.