Conformal coating is always required when electronic printed circuit boards (PCBA) are used in products that perform safety-related tasks or are used in harsh environments. This applies, for example, to automotive applications, defense technology, aerospace, marine, lighting, and industrial applications, as well as to the Green Energy sector. The fluorescent coating, which can be applied by spraying or dipping, protects against environmental influences such as moisture, dirt, dust, condensation, and temperature differences. Using uv light for conformal coating inspection makes the applied coating visible, allowing you to check whether there is too little or too much coating in the designated areas.
As a result of miniaturisation, components have become more densly packed. The insulating effect of the protective coating allows designers to reduce the distance between PCB traces. Automated optical inspection of the protective coating (Conformal Coating Inspection - CCI) helps to ensure the quality of coated PCBA. The presence and quantity of the coating is checked according to the specifications of a coating plan. This involves checking whether the coating has been applied correctly according to the specifications of the coating plan – i.e. that there is neither too little nor too much coating in the designated areas.
Quality check with protective coating inspection
Multi Line CCI features a high-resolution color camera with telecentric optics for highly detailed images. In combination with UV (ultraviolet) illumination from above and from the side, high-contrast images are generated. The UV illumination causes the fluorescent particles in the coating to glow, revealing defects such as scratches and bubbles. Above all, however, this inspection also reveals whether there is too much or too little coating on the respective assembly.
Optionally, the system can be equipped with up to eight oblique view cameras to inspect connectors, for example, in an inclined view. In addition, a camera module is installed to determine the coating thickness at various points on the PCBA.
The Multi Line CCI recording shows that too little coating has been applied to the pad.
The Multi Line CCI image shows that too much coating was applied to the connector
The Multi Line CCI image shows that too little coating was applied to the component and pad
The Multi Line CCI image shows that too much coating was applied to the pad
Paint coating thickness measurementThe coating thickness can be measured at specific points, as a line or over an entire surface.
Coating recorded under UV illumination with side camera
Coating photographed with white illumination from side camera
Coating under UV lighting with top camera
Coating photographed with white illumination from top cameraDouble-sided inspection of conformal coatings
For inspection of submerged PCBA, the Multi Line CCI can be equipped with inspection from above and below. This allows painted PCBA to be inspected simultaneously from both sides in the shortest possible time.
The system is mainly used after the drying oven. Wet inspection is also possible. Depending on the configuration, the CCI also allows PCBA to be returned under the system.
Software for generation of the test programme
With the PILOT AOI software, you can generate an inspection programme for coating inspection in just a few minutes. The areas to be inspected are defined on the basis of CAD data (Gerber/assembly data, ODB++, OPM, etc.) and the coating plan for a PCBA. MagicClick generates an inspection programme in just a few minutes.
This software platform is also used for the generation of AOI and SPI programmes.
This software platform is also used for the generation of AOI and SPI programmes.
MES connection
The Multi Line CCI has SMEMA and HERMES interfaces. It can also be connected to customer MES systems via MES plug-ins.
