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PCB cleaning

During the production of printed circuit boards, fiber-reinforced plastics are coated with copper. Subsequently, the conductors are etched out of the flat copper layers and the respective components are soldered to the circuit board. An indispensable process step is the cleaning of the circuit boards to remove impurities, such as filmic and particulate flux, resin, and solder paste residues. Mostly, single, multi-chamber, and continuous systems are used. The impurities would lead to electrical failures andcorrosion of the circuit boards or assemblies.

The cleaning process has a significant impact on the lifespan of the products and increases their reliability. The electrical parameters of the electronic assemblies are improved by cleaning. Therefore, continuous bath monitoring is of enormous importance.

LiquiSonic® Sound velocity measurement

Application

The cleaning process of printed circuit boards consists of a cleaning step followed by one or more aqueous rinsing steps. This often takes place in a spray cleaning system, where precisely dosed cleaning solution is sprayed onto the assembly through nozzles. Aqueous cleaners, such as Atron, as well as non-aqueous cleaners are used. An aqueous cleaning process generally offers the advantage that the cleaners do not have a flash point.

Through many years of experience, the LiquiSonic®® process measurement system®proves to be a reliable partner in bath monitoring and impresses with the analysis of the concentration of different cleaner types through precision and continuous data recording. This avoids waste due to incorrect dosing and constantly controls product quality.

Installation

The LiquiSonic® Sensors are preferably installed in the circulation loops after the pump or directly in the cleaning or rinsing bath. The LiquiSonic® bath monitor can be connected to up to 4 sensors. This makes it possible to monitor several measuring points simultaneously.

The sensor electronics are housed in a sealed stainless steel enclosure with protection class IP68, which allows cleaning of the process equipment with a high-pressure cleaner without any problems.
For baths with non-aqueous cleaners, SensoTech also offers sensors with appropriate ATEX, IECEx, and FM certification.

Customer benefits

LiquiSonic®reduces time-consuming laboratory measurements:

  • Time required: 2 x 0.5 h per day

LiquiSonic®serves process optimization:

  • Rapid detection of quality changes with documentation of measurement data
  • Optimization of the service life of the cleaning baths
  • Avoidance of overdosing or premature bath changes
  • Maintaining cleaning performance (process reliability)
  • Avoidance of over- and under-dosing and saving on material costs

The LiquiSonic® Measurement system enables continuous analysis of the bath composition. The measured values are available online or are forwarded directly to the control system. This allows immediate response to deviations in the measured value, for example by sharpening or changing the bath. This reduces quality fluctuations.