With increases in PCB complexity and component densities, selective soldering is a popular technique for mixed technology PCB boards containing a small number of through hole joints or components.  You can use a selective solder machine to replace more time-consuming and expensive systems using wave or hand soldering with fixtures – systems that are also not as repeatable. 

    Reference equipment link:

   Ersa Selective Soldering Systems

Vector Selective Soldering Machines

Mini Selective solder machine  base on Electromagnetic solder pump. While electromagnetic solder pumps used for selective soldering have several functional advantages, at the same time they inherently have several limitations.

Advantages:

• No moving parts in contact with solder
• stable wave height
• maintenance free
• better than impeller solder pumps
• standup better to lead-free solder alloys than impeller solder pumps
• low nitrogen consumption
• do not wear out
• low cost
• Generates less dross
• Compact and easy to package inside machine

This project uses  solder pot base on  Electromagnetic solder pump    link 

LongLife solder nozzle ，compatible with Kurtz Ersa

SPECIFICATIONS

• PCB holder and X Y Z-axis drive mechanism

Maximum PCB Size              320 mm x 250 mm

Minimum PCB Size              50 mm x 50 mm

PCB Thickness                  0.8 mm - 3.0 mm

PCB Warp                     0.5 mm  maximum

Maximum PCB Weight           2 kg  including components

Component Lead Length          4 mm recommended maximum

PCB Edge Clearance             3 mm for components ;5 mm for solder pad edge

Positional Accuracy            ±0.01 mm   

X-Axis Resolution              0.01 mm

Y-Axis Resolution              0.01 mm

Z-Axis Resolution              0.01 mm

Travel Speed (While Soldering)   Programmable from 0.1 mm/sec - 50.0 mm/sec

Travel Speed (Between Points)   500 mm/sec maximum

• Solder wave and bath

Solder Types        Both Lead-Free and Conventional Sn/Pb Solders; Second Separate Solder Pot Recommended

When Using Both Types

 Nozzle Type        2.5, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 12.0,14.0, 16.0, 20.0 mm Inner Diameter Nozzles Available 

Solder Pump Type               Electromagnetic solder pump

Solder Wave Height              3~6mm

Solder Wave Height Adjustment    Controlled by Fieldbus (RS485/CAN etc.) 

Solder Wave Height Accuracy      ±0.1 mm

Solder Pot Capacity            Approx. 8kg

Solder Temperature           400⁰C maximum (600⁰C optional)

Solder Melt Time at Startup    Approx. 20 min.

• Controller and Optional accessories

Controller                ...