Do I Need To Clean PCBs Before Wave Soldering?

As a printed circuit board manufacturer, eventually, you'll have to decide whether PCB cleaning processes and machines will have a home on your assembly floor. Cleaning usually occurs before wave soldering to reduce the amount of flux and other residue left on each assembly. At Capital Equipment Exchange, in McHenry, Illinois, we understand these challenges.

So, to clean or not to clean, that is the question.

How Do PCBs Get "Dirty"?

The primary source of contamination on a "dirty" PCB is leftover flux. Old rosin-based fluxes required specific cleaning techniques, but today's no-clean fluxes only require heat to decompose. Unfortunately, if a molten solder is applied to your boards to insulate the flux, it may not get the needed heat.

The No-Clean PCB Process

In order to produce PCBs without cleaning equipment and processes, you'll have to invest in no-clean fluxes and solder pastes. These ensure that any residues left behind will be both non-conductive and non-corrosive to your boards and components.


  • Reduce cycle times
  • Reduce materials handling defects
  • More floor space for other equipment
  • Less maintenance & materials to manage
  • Reduce your per assembly cost


  • Paste, flux, solder & touch up flux must all be compatible
  • Screen printing machines must be consistent
  • Changes to screen printing stencils must be documented
  • Must avoid handling & contaminating boards as much as possible
  • Additional training is needed for hand soldering technicians
  • Can affect long term PCB reliability
  • May still need manual cleaning from time to time

Reasons To Clean Your PCBs

Even with the use of no-clean flux and solder, you may choose to clean your circuit boards before wave soldering to ensure that no residue remains. Dirty boards can have issues with reliability and longevity, costing you quality over time. You may find that introducing a cleaning process to your line pays for itself because of these factors.


  • Flux residues can cause failures
  • Better conformal coating distribution
  • Better coating adhesion & reliability
  • Produces PCBS that handle harsher environments


  • Must keep processes consistent & measured
  • May need to invest in contamination testers
  • Today's components can be challenging to clean
  • Hard to get into smaller areas & between components
  • Must get wave, reflow & wash schedules right

Save With Used PCB Equipment

If you are looking for more ways to produce quality PCBs without breaking the bank, we encourage you to explore our available used wave solder machine inventory. Contact us at Capital Equipment Exchange, in McHenry, Illinois, to place your order or inquire about the latest additions to our inventory. We look forward to helping you save money with used SMT machines you can rely on.