Differences Between Red Glue Process andPure Solder Paste Process in SMT Assembly
Red Glue:
Red glue is a type of polymer thatsolidifies upon heating, with a solidification point of around 150°C. It transitions directly from a paste to a solid state when itreaches this temperature.
Properties of Red Glue:
Viscosity and Flow Characteristics: Redglue has specific viscosity and flow properties.
Temperature Characteristics: It solidifiesat a lower temperature compared to solder paste.
Wetness: It is designed to securely bondcomponents to the PCB surface, preventing them from falling off.
What is Solder Paste?
Solder paste is a new type of solderingmaterial developed for SMT assembly. It is a mixture of solder powder, flux,and other additives, forming a paste.
Solder Paste Characteristics:
Conductive Soldering: Used primarily forsoldering electronic components like resistors, capacitors, and ICs on PCBsurfaces. It has conductive properties necessary for electrical connections.
Differences Between Red Glue and SolderPaste:
1. Function: Red glue is used for securingcomponents and does not conduct electricity. Solder paste is also used forsecuring but provides electrical conductivity.
2.Soldering Process: Red glue requires wavesoldering for the final soldering process. Solder paste is typically used withreflow soldering.
3.Temperature: The temperature for wavesoldering red glue is lower than that used for solder paste.
4.Usage: Red glue is used mainly as anauxiliary material for fixing components. Solder paste is commonly used forboth fixing and soldering due to its conductive properties.
Selection Criteria for SMT AssemblyProcesses:
No Traditional Through-Hole Components: ForPCBs without traditional through-hole components, solder paste is used(including single-sided, double-sided, or multi-layer boards).
Single-Sided Boards with Through-HoleComponents: Red glue is used on the solder side of the board.
Double-Sided Boards with Through-HoleComponents: Solder paste is used on one side, and red glue is used on the otherside.
Red Glue Process vs. Solder Paste Process:
Red Glue Process: Requires wave solderingfor completing the soldering of components to the PCB, which is a longerprocess and increases labor and manufacturing costs.
Solder Paste Process: Completed with reflowsoldering, which is a shorter process, reducing labor and costs, and shorteningthe production cycle, thus improving market competitiveness.
Differences Between Solder Paste Screen andRed Glue Screen:
Hole Placement:
Solder Paste Screen: Holes are directlyaligned with the solder pad positions (1:1), allowing solder paste to bedirectly applied to the PCB pads for soldering.
Red Glue Screen: Holes are placed betweenthe component pads, as red glue is used for applying glue and fixingcomponents.
Application: Solder paste screens and redglue screens are used according to the specific PCB component assemblyprocesses. For PCBs with fewer surface-mount devices and more through-holecomponents, using a red glue screen process may be more appropriate.