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Securing PTH Parts with Selective and Wave Soldering
By Akber Roy, CEO, Rush PCB S
elective soldering and wave soldering are two widely-used soldering attach- ment processes in electronics produc-
tion, basically for soldering PTH (Plated Through Hole) components onto printed cir- cuit boards (PCBs). Although both processes are popular, they vary in process, benefits, limitations and applications. As a fully inte- grated PCB manufacturer, Rush PCB han- dles both the fabrication and assembly of cus- tom PCBs and uses these solder attachment processes
Selective Soldering Selective soldering is a technique in
which a specific area or site on a PCB is sol- dered, typically involving through-hole com- ponents. A soldering nozzle directs a con- trolled ‘fountain’ of molten solder to the desired component site, generally contacting the component leads and PCB contacts only, without touching other regions of the board. The PCB is usually transported on a
conveyer, and the robotic arm or nozzle trav- els along the targeted solder joints. It deposits solder only on those joints, and the rest of the board is untouched.
Wave Soldering Wave soldering is a process by which the
entire bottom side of a PCB is drawn through a stationary flowing wave of molten solder.
Wave soldering diagram.
with this wave, and solder wets to all exposed metal leads and pads, forming the physical and electrical connections.
Speed and Throughput: Selective solder- ing is slower than wave soldering, since it
The process is used most commonly for sol- dering bulk through-hole components. In this soldering technique, a wave-solder
pallet or fixture holds the PCB from the solder- ing side, which covers pre-soldered SMT com- ponents, leaving PTH leads exposed. The PCB is then drawn across the flowing wave of molten solder. The board comes into contact
individually targets each joint. It is appropri- ate for small batches or boards with complex, localized soldering needs. Wave soldering is quicker than selective
soldering, particularly for large production runs. It is a cost-effective method of soldering large numbers of components in a single pass.
Suitability: Selective soldering is better suited for boards that are densely populated or have a mix of through-hole and SMT parts. This is perfect for prototypes or small batches where accuracy matters the most. By using a wave solder pallet, one can use
wave soldering for mixed technology boards as well, but this is ideal for simple, high-volume boards that have mostly through-hole compo- nents. This is less ideal for complex designs or boards that have many delicate or small SMT components.
Limitations: Selective soldering is slower than wave soldering, particularly for larger boards or for high-volume production. It also requires complicated set up with each new design of the board, contributing to overall costs.
Wave soldering is less accurate, which
may lead to unwanted solder bridges or too much soldering. Not ideal for SMT compo- nents or boards with numerous fragile parts. This may also cause thermal stress or dam- age to delicate components.
Continued on next page
June 2025
FLS Flying Probe Test System Effective testing solution
a circuit board's lifecycle that can be used throughout
• Prototype/Product Qualification • PCB Assembly • Manufacturing Process Test • Functional Test • Repair Depot Test
acculogic.com
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