The particle suction extraction

The complementary dry extraction process

Particle extraction is carried out by suctioning the dry adhering particles from component surfaces or from specific control areas. The particles are loosened from the surface with nozzles, extracted and specifically collected or deposited on sample carriers such as laboratory bottles, analysis filters or particle traps.

The technical cleanliness of automotive parts, but also parts and components in the field of electrical/electronic production is becoming increasingly important in connection with new technologies, and thus cleanliness testing of parts and the process environment is also gaining in importance. This indirect testing requires a sampling step called extraction. Wet extraction and air extraction by air jet have been state of the art for years. In the meantime, the range of components has changed considerably in connection with e-mobility and assistance systems, for which even these methods have reached their limits. Large battery components can no longer be extracted in a closed cabinet. Also the demand for testing methods directly in the process environment cannot be fulfilled with the established methods.

CleanControlling has therefore developed the complementary method of suction extraction. This method represents a variant of the air extraction described in the standards. Here, the qualification of the inspection up to the light-optical analysis is carried out according to VDA 19.1 / ISO 16232 and thus leads to reproducible results. Suction extraction is particularly characterized by its independence from closed test rooms and mobile use.

 

Application areas

Advantages of suction extraction

  • Non-destructive test (air/ESD protection) means the component can be reused after testing
  • Particle monitoring can be used at any point on the production line
  • Simple testing of extensive components thanks to the flexible test system
  • Selective testing without masking sections possible
  • Application-specific testing of components which must not be exposed to liquid media
  • Reduced operational and logistics costs for component tests in the process environment and liquid extractive media no longer used.
Hand in weißem Handschuh saugt mit Bürstendüse eine elektronische Komponente ab.
Suction of particle contamination from the component with brush nozzle

Effectiveness of suction extraction

Indirect testing

An indirect test is used to identify particle contaminants mainly produced during the manufacturing process. These are extracted during the component’s sampling stage before microscopic analysis consisting of measurement, counting and type identification of particles. A dry or liquid medium is used for this extraction process.

The main extraction processes include:

 

Pressure-rinsing

Air jet

Suction

A working grout of the German Electro and Digital Industry Association (ZVEI e.V.) carried out a comprehensive study to investigate the effectiveness of these three extraction processes in 2021 based on a large-scale series of tests with different electric and electronic assembly groups. A number of components were taken from HV plug-in connectors, connector strips and printed circuit boards from the same production batches and then tested and analyzed using these three extraction processes. The study focused on the total number of particles in several individual analyses and the breadth of their dispersion among them.

The analysis showed that all three methods studied reliably extracted the largest metallic particles. The results also reveal that, although components from the same batch have a wide dispersion, this dispersion shows an adequately normal distribution so that mean values and standard deviations can be derived from it.

    Statistical evaluation of effectiveness

    The statistical evaluation shows that the procedures are comparable with each other.

    As a general rule, there is

    • a correlation of 88–96% between air jet and pressure-rinsing with a mean rel. deviation of -24% 
    • a correlation of 97–99% between suction and air jet with a mean rel. deviation of +34% 
    • a correlation of 96–98% between suction and pressure-rinsing with a mean rel. deviation of -1%.

    Conclusion of the study

    All extraction processes are suitable for determining and comparing the surface cleanliness of electronic components. Firstly, this is thanks to the reliable extraction of the largest particles and, secondly, due to the good correlation between the processes.

    Suction extraction in action - application videos

    Detailed application videos about the design, blank value, the different types of use up to the cleaning of the particle suction extraction system C|PS² can be found here:

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