How to Optimize Your Circuit Board Cleaning Equipment

Industrial operations rely on computerized systems to perform various operations. Manufacturers develop printed circuit boards (PCBs) to perform these simple and complex functions. An important issue experienced by manufacturers involves keeping circuit boards clean during production. Any types of contaminants introduced into the process may cause printed circuit boards to experience damage or malfunctions.

While clean rooms assist in preventing contaminants from entering workspaces and shop floors, particulates may inadvertently come from other places. Such contaminants may include fingerprints, resins such as adhesives, salts, flux residues, ions, board particles, or solder balls. Circuit board cleaning tackles the dirt, contaminants, and other particles.

Circuit Board Cleaning Overview

Circuit board cleaning go through different cleaning stages depending on the production step. The cleaning steps may occur before and after wafer sawing, drilling, soldering, or plating processes. It may also occur before and after adding fluxes as well as during the times when workers have been handling the circuit board constantly.

The circuit board cleaning process is based on the types of equipment and cleaning chemicals used. They may also depend on the types of circuit boards, such as lead-free or lead-based. In addition to removing the common contaminants that have to be removed to ensure the printed circuit board works properly, cleaning processes also focus on removing residues introduced during production.

These residues may simply be perspiration from hands, salts, acids, flux activators, or plating chemicals. While the residues may be there in small enough quantities that will not impact the functions of the circuit board, removing these residues may improve the PCBs operations and longevity in the application.

PCB Cleaning Process

The cleaning process typically begins by pre-washing the PCBs to remove any types of large contaminants on the surface. This process helps to get rid of most contaminants and residues.

Next, workers and equipment perform a more specialized cleaning to get rid of any leftover contaminants of the circuit boards. During the washing process is an anti-drag out phase, where the liquid of the water or chemicals is prevented from being dragged out with the circuit board

After the washing, the circuit boards become rinsed off as methods are used to get all surface areas and crevices to ensure no remaining cleaning solution is left on the board. Just like during the washing stage, an anti-drag out have is performed during rinsing.

Lastly, the PCBs go through a drying phase. The drying phase utilizes blowers that propel high pressurized and high temperature gasses, such as nitrogen, or air onto the circuit board. This prying stage helps to remove all moisture.

Circuit Board Cleaning Equipment Options

PCB manufacturers rely on a wide range of cleaning equipment. The equipment may be as simple as soft-bristle brush, microfiber cloth, and cleaning agent such distilled water or isopropyl alcohol to perform fast cleanings on individual circuit boards. Other equipment may consist of large standalone machines made to perform batch circuit board cleanings in larger quantities. Here are some clearing equipment options:

Alkaline texturing equipment uses modules connected in a series to direct cleaning chemicals onto the circuit boards using flat fan nozzles, which are available from Lechler. This method is used during wafer sawing processes to remove contaminants and damage. The machine may employ ready-to-use chemicals that are sprinkled onto the wafers, then blowers dry the wafers.

Wafer moistening equipment helps prevent impurities dry onto to the printed circuit board after the sawing process. This equipment uses may use Lechler hollow cone nozzles to direct a very fine spray mist onto the wafer's surface. The spray softens the wafers and moistens the contaminants and residues so they can be removed.

Other types of equipment and components are employed during the etching, stripping, and development phases of the PCB. The Lechler 646 series nozzles are used that have a bayonet quick-locking system used in an inline process.

Lastly, some manufacturers still have ultrasonic cleaners to remove circuit board contaminants. Many industries, including NASA, have moved away from this method due to end cap separation of components and bond wire/pad damage.

PCB Cleaning Methods

Manufacturers may determine specific circuit board cleaning methods based on the number of circuit boards going through the production process and the types of common contaminants found on the boards. Three types of cleaning methods include manual, batch/inline, and gas phase.

Manual: The manual method simply relies on the worker performing all the stages of the cleaning process using various tools. While this procedure provides the most attention to detail, it also involves increased handling of the circuit boards and may lead to human errors.

Batch/inline: Batch/inline methods are automated processes that are used to clean no-flux residues. The method can clean small and large batches of circuit boards at once and in a uniform clearing production line.

Gas phase: For this method, a chemical solvent is boiled until it becomes steam or a gaseous state. The vapor is directed onto the circuit board to separate the contaminants from the surface. This method is also called vapor cleaning.

Cleaning Agents for Printed Circuit Boards

Cleaning agent types vary based on the equipment and methods used during the washing and rinsing methods. Selecting a cleaning agent may depend on the contaminant and its location.

Water-based methods use a water-based PCB cleaning agent and deionized water for rinsing.

Semi-aqueous methods may employ solvents and deionized water in dip tanks during spray-under-immersion applications. Many of the solvents are organic or halogen-free.

Water-free methods rely on modern solvent-based cleaners applied as vapor rinses or in dip tanks.

Lechler: Nozzle Cleaning Solutions

At Lechler, we know the importance of using the right equipment at the right time to perform reliable PCB and circuit board cleaning methods that are also cost-effective. By offering a wide selection of application nozzles, you obtain the cleaning tools to ensure proper application of cleaning and rinse solutions to ensure all contaminants are removed from your PCBs. For more information about our products, contact us today.