SMD adhesive, also known as Surface Mount Adhesive, is commonly used to bond components with pin contacts or SMDs (Surface-Mounted Devices) to the PCB before soldering. This process helps secure components such as capacitors, electrolytic capacitors, and coils onto the circuit board. The adhesive cures quickly, preventing components from shifting or falling out of place on the PCB. Once secured, the components can be reflow-soldered in a single step, optimizing production time and efficiency.

SMD adhesive is typically composed of a mixture of hardening agents, pigments, and solvents that are evenly distributed in a red paste. It is primarily used to fix components to printed circuit boards, and is typically applied through a point-coating method. The ideal SMD adhesive should possess the following characteristics:

• Connection strength: The adhesive must provide strong bonding after curing and should not peel off even at the soldering temperature.
• Dispensing characteristics: The adhesive must meet the following requirements for ease of use during dispensing:
  • Compatibility with various mounting technologies.
  • The ability to control the dispensing amount of each component precisely.
  • Easy adaptation to different component types.
  • Stable dispensing volume.
• Compatibility with high-speed machines: The adhesive must be suitable for high-speed dispensing and mounting processes. Specifically, it should not draw or shift the components during high-speed dispensing, ensuring that the components stay in place as the PCB is transferred through the system.
• No drawing or slumping: Once the adhesive is applied to the pad, it should not cause any electrical connection issues or spread out, ensuring the pads remain clean and the adhesive does not interfere with the PCB’s functionality.
• Low-temperature curing: The adhesive should cure effectively at low temperatures, ensuring that components do not require heat-resistant cartridges or extended reflow furnace exposure. This helps maintain the integrity of the components during the curing process.
• Adjustability: The adhesive must be compatible with reflow soldering and pre-coating processes. It should cure first, before soldering, ensuring that the components are securely fixed in place and preventing them from sinking or misaligning during the soldering process.

If you have any questions about PCBs or PCBA, please feel free to contact me at info@wellcircuits.com.