The hardware

The EFA Picture series enables the creation of overall microscopic images for printed circuit boards. With achievable resolutions of up to 5000 dpi, even structures of only 50 µm with approximately 10 pixels are reliably displayed. In contrast to a microscope, EFA Picture forms the full circuit board in this extremely detailed resolution.

Apart from special sizes, printed circuit boards with dimensions up to 500 x 500 mm are produced. No digital camera can photograph this area with a single picture in the required resolution, so that with the help of the hardware, several individual pictures of the circuit board must be made. The breakdown into these individual images and the subsequent sewing of them to the desired microscopic overall image is then the task of Software duos EFA Capture & EFA Stitch.

However, the quality of these individual recordings is significantly influenced by the correct answers to the various requirements.

Lighting requirements

The right lighting has always been very important in photography. However, the demands placed on an optimal circuit board holder are even higher.

On the one hand there are the many reflections, which are caused by the numerous solder joints on soldered circuit boards. The metallized surfaces of components also contribute to the formation of reflections. On the other hand Labeling of components often not performed with a clearly recognizable color, but in many cases only labeled with a laser. Then the labeling of these components can usually only be recognized with a side view. Also the Marking pin 1 and therefore the correct alignment of the associated component can often only be recognized by a beveled edge. In many cases, however, this edge is difficult to see in the top view.

In order to avoid these difficulties with the recordings, two different lighting sources are used in addition to various filters. On the one hand Barlightwhich is responsible for the general brightness. The other one Dark field illumination, which makes surface structures more clearly recognizable due to their angle of incidence. What is decisive, however, is the correct ratio of the brightnesses between the incident light & #8211; and the dark field lighting. This ratio must be determined individually for each printed circuit board of different types. 

For the management of such parameters is the EFA Capture software responsible. It assigns an individual recording profile to each circuit board type and thus allows the creation of overall microscopic recordings with the same recording parameters.

Mechanical and optical requirements

In order to achieve resolutions of up to 5000 dpi evenly over an area of approx. 0.25 m², precise guidance of the digital camera is absolutely necessary. Continuous focusing is not possible without sufficient parallelism between the sensor level and the printed circuit board level over the entire travel range. Therefore, high-precision and torsionally rigid linear axes are used in all EFA devices.

The requirements for the lens are just as high. It has to be low in index, achieve image scales in the macro range and be affordable. Since the devices of the EFA Picture series are professional digital cameras use, all are available to the user high quality macro lenses various manufacturers available. The design of the EFA devices supports all lenses with a minimum distance of 42 cm between the sensor level and the circuit board surface.

Handling requirements

The correct handling of printed circuit boards is a prerequisite for all EFA devices that should not be underestimated.

Detail view of the extended drawer of an EFA desktop device ..

In the case of one Desktop device an operator must move the circuit board from the previous station to the desktop device and then from there to the next station. Short distances with few obstacles can avoid many handling problems.

On the other hand, the correct clamping of the circuit board in the desktop device itself is often more problematic. Compact circuit boards usually have only small edges and little reserve for errors that can occur during insertion. It is therefore helpful to have free access to the support rails and a finely adjustable adjustment of the width of these support rails. Both were realized in the devices of the EFA Picture series! The support rails are over one Width of spindle can be changed precisely and the support mechanism is completely removable from the device.

Moved back ..

In the case of one Inline device The controller of the underlying conveyor takes over the handling of the printed circuit boards, i.e. the transfer from the previous line participant, the transport in its own sub-segment and the transfer to the subsequent line participant.

It only becomes interesting in the event of a fault, i.e. when the inspection of a printed circuit board was faulty and a repair is pending! In this case, the devices of the EFA Picture series can be completely moved back so that the circuit board does not have to be taken off the belt or ejected through further belt segments. The operator can carry out the repair directly on the line. There is no need to tolerate the printed circuit board in the event of a fault!

Ergonomic work

Ergonomic work should not be neglected either. Since all devices from the EFA Picture series have multi-touch screens, tasks can be triggered more quickly with the touch of a finger than with a pointing device. Operation in a standing position in front of the device is therefore recommended.

This is why the height of the screens in this series can also be adjusted to meet the ergonomic requirements for operators of different heights. While the height adjustment in the desktop devices has to be carried out manually, the inline devices have a stepper motor for easy height adjustment via switch.

On the cutting edge

All devices of the EFA Picture series are easy to maintain and forward-looking designed. By using professional digital cameras, EFA users are faster and therefore more frequent with the innovations in the field of digital cameras faced. The average market availability of a new camera model is around 2 years. After that, the successor took the reins and raised the bar again.

However, since all EFA devices recalibrate themselves and can thus react to new environmental conditions, replacing the current camera model with a newer model is no rocket science. In many cases, the user can therefore replace the camera with a newer model.

So the EFA user is always up to date!