Red glue process is a process that uses a special thermosetting adhesive (usually red) to fix electronic components onto printed circuit boards.
Red glue has the characteristics of good viscosity, high temperature resistance, and good electrical performance, which can ensure the firm fixation of electronic components on PCBs.
The main steps of the red glue process include:
Gluing: Apply red glue evenly to the solder pads of the PCB through a dispensing machine;
SMT: Place electronic components on solder pads coated with red glue according to design requirements;
Curing: Heat the pasted components through a hot air reflux furnace until the red glue is cured, forming a strong bond between the red glue and the solder pads and components;
Welding: After the red glue is cured, wave soldering, hot air reflow soldering, and other methods are used to weld the components and solder pads to achieve electrical connections.
The difference between solder paste process and red glue process
1. From the appearance, the color of solder paste and SMT red glue is different, and the solder paste is in a gray paste shape; SMT red glue is a red paste.
2. In terms of performance, once SMT patch red adhesive is heated and hardened, it will not melt even when heated again. This means that the thermal hardening process of SMT patch red adhesive is irreversible, which is the curing phenomenon in SMT patch red adhesive. After soldering, there is no solidification phenomenon in the solder paste, and the formed solder points can be melted back into a molten state at high temperatures. If the soldering is poor, the tin can be removed using a solder absorber.
3. From a process perspective: Red glue generally adopts a dispensing process, suitable for use on circuit boards with fewer dots; The solder paste generally adopts the reflow soldering furnace printing process, which can print a large number of circuit boards at once.
4. From a quality perspective, compared to solder paste, red glue is more affected by the climate and environment, has a higher rate of defects after welding, and is more prone to falling parts and missing soldering. And solder paste has strong weldability, and the firmness of welding is relatively high.
5. In terms of manufacturing cost, the selectivity is different:
1) When there are many SMT components and relatively few plug-in components, many companies generally use solder paste process, and plug-in components are processed and welded after processing.
2) When there are many plug-in components and relatively few SMD components, the red glue process is generally used, and the plug-in components are processed and welded after processing. Regardless of the process used, the purpose is to improve yield and quality.
6. In terms of usage, red glue generally plays a fixing and auxiliary role. Solder paste is the true welding function.
7. In terms of conductivity, red glue is non-conductive, while solder paste is conductive.
8. In terms of furnace temperature: Red glue has a lower temperature when passing through a reflow soldering machine, and after reflow soldering, it still needs wave soldering to be welded. The temperature of solder paste in the reflow soldering machine is relatively higher.
