The function, composition, purpose and usage of LED patch adhesive

1. The role of LED patch adhesive

Surface mount adhesives (LED patch adhesives, SMA, surface mount adhesives) are used for wave soldering and reflow soldering. They are mainly used to fix components on printed circuit boards. They are generally distributed by dispensing or steel screen printing to keep the components in place on the printed circuit board (PCB) to ensure that the components will not be lost during the transmission process on the assembly line. After the components are attached, they are placed in an oven or reflow soldering machine for heating and hardening. It is different from the so-called solder paste. Once heated and hardened, it will not melt again after heating. In other words, the thermal hardening process of the patch adhesive is irreversible. The effect of SMT patch adhesive will vary depending on the thermal curing conditions, the objects to be connected, the equipment used, and the operating environment. When using it, the patch adhesive should be selected according to the production process.

2. Composition of LED patch adhesive

Most surface mount adhesives (SMA) used in PCB assembly are epoxies, although acrylics are also used for special purposes. After the introduction of high-speed glue dispensing systems and the electronics industry mastered how to deal with products with relatively short shelf lives, epoxy resins have become a more mainstream adhesive technology worldwide. Epoxy resins generally provide good adhesion to a wide range of circuit boards and have very good electrical properties. The main ingredients are: base material (i.e., main polymer material), filler, curing agent, other additives, etc.

3. Purpose of using LED patch adhesive

a. Prevent components from falling off during wave soldering (wave soldering process)
b. Prevent components on the other side from falling off during reflow soldering (double-sided reflow soldering process)
c. Prevent components from shifting and standing still (reflow soldering process, pre-coating process)
d. Marking (wave soldering, reflow soldering, pre-coating). When printed boards and components are changed in batches, use patch glue for marking.

4. Classification of the use of LED patch adhesive

a. Dispensing type: Glue is applied on the printed circuit board by dispensing equipment.
b. Scraping type: Glue is applied by printing and scraping on a steel or copper mesh.