![]() In high-density boards, it’s possible for solder balls to become trapped in leftover no-clean flux residue between components. In low-voltage, low-density boards, the leftover flux residue probably won’t matter. Ensure more accurate inspection and quality control.Ensure better adherence of conformal coatings.Prevent moisture absorption into the flux residue.Prevent outgassing from the flux residue.Prevent contamination of circuits by residues.Prevent leakage currents between different circuits.There are several reasons to clean this leftover material: The problem with these residues is that they can be conductive after they are deposited on the PCB, or they can slowly become conductive over time. What’s Wrong With No-Clean Flux Residues? If you look at a hand-assembled PCB under light at an angle, you can most likely see the leftover no-clean flux residue covering the surface of the PCB a/s a thin transparent film. The residue that is leftover by flux is claimed to not require any cleaning, meaning you can leave these residues on the PCB and you should not expect any interference with product performance. These solder pastes also come in lead-free varieties that intend to comply with Pb-free/RoHS directives.Įxample no-clean solder paste that can be purchased from Digi-Key.Īll solder flux leaves behind residues, including no-clean flux. Typically, the off-the-shelf solder pastes that are available to consumers include a no-clean flux, and could best be called no-clean solder pastes. Solder pastes used for manual soldering, selective soldering, or reflow soldering will include some type of flux, and this is commonly a no-clean flux formulation. ![]() In general there are three types of solder fluxes: water soluble flux, rosin-based flux, and no-clean flux (which may contain rosin). In other cases, the design will require thorough cleaning in order to remove leftover chemical residue, including no-clean flux residues. In some designs, the leftover residue will probably not interfere with your board’s functionality. ![]() The very name of this product implies that it will never require cleaning, but studies have shown that this is not necessarily the case. Within cleaning processes, there is one unfortunately-named product that implies cleaning is not needed: no-clean flux.Īll PCBAs must undergo soldering processes, and within reflow soldering, there is a type of solder flux known as no-clean flux. These include things like testing, inspection, cleaning, and quality control procedures that ensure your board is produced to industry standards and your operating requirements. PCB manufacturing involves many procedures that are sometimes ignored or overlooked. No-clean solder paste is being dispensed from an automated machine. ![]()
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