Optimal optical inspection solution

Nordhausen based EMS provider relies on innovative semi-AOI solution

The automation of optical inspection for small and medium batches poses a challenge for EMS service providers. Manual inspection processes are time-consuming, error-prone and offer only limited security. AOI solutions are not useful for optical inspection of small and medium series. On the other hand, time savings and test security are provided by semi-AOI solutions.

appeared in the Productronic 09/2013

In line with the philosophy "Special tasks require special solutions!", Hörmann IMG GmbH offers innovative products with customer-oriented solutions. As part of the Hörmann Group, the Nordhausen-based company specializes in the fields of high-quality electronic systems, innovative vehicle drive technology such as hybrid and electric drive systems, energy technology in the field of renewable energies, and EMC and materials testing services. The close cooperation with universities as well as science and research institutions ensures future-oriented services and products with high quality and reliability.

From this orientation as E2MS service providers have a broad product range with high expectations of flexibility in production. Many product changes, small quantities and a high component density make high demands on the optical inspection.

Until now, the visual inspection using a vision system VS8 was carried out purely manually. Existence and poling were checked in the four-eyes principle. Depending on the component quantity and density, the initial sample inspection of assemblies may in some cases comprise 8-10 hours with 2 workers depending on the component quantity and density. A component-by-component inspection required a high degree of concentration - including the test procedure. The long work with the microscope and the constant changes of focus led to a high load on the eyes and a permanent working longer than 4h is impossible. In addition, the random checks often left the feeling that they might not have controlled an area.

In order to ensure the high quality standard under the increasing requirements for the future, Hörmann sought a solution in 2012 to support optical inspection. The disadvantages of the manual test should be eliminated and a significant acceleration of the process should take place.

As a possible solution, an AOI system was initially favored. During the presentations and reference visits, however, it quickly became apparent that the AOI's approach to the requirements of small and medium series is not viable. The high programming effort and the amount of manually reworked pseudo errors do not lead to an acceleration of the test process. This results in very high programming and one-time costs, which can not be reduced to small quantities of modules to be controlled. In addition, at least one qualified specialist would have been required for AOI programming and operation, which would have tied up additional resources. It was clear that another inspection procedure had to be found.

Small and medium quantities require flexible optical inspections

Hörmann has now evaluated several semi-AOI systems and in October 2012 decided to use the EFA Inspection solution from LEBERT Software Engineering (LSE for short).

"With the camera system, the system is technically better than comparable solutions, is user-friendly and offers a wide range of application options," says Mr. Linde, authorized signatory and division manager for Electronic Systems at Hörmann.

The future orientation of the solution was also convincing.

“It is important to us to integrate customer requirements into the existing software again and again. This is the only way to create a practice-oriented system that can be used in a variety of ways! ", Mr. Lebert, Managing Director of LSE, emphasizes this aspect. 

EFA Inspection automates the inspection process and presents all the information you need on a single image plane. With these requirements, the operator can quickly and safely submit a review. The programming effort for the system is only a few minutes. You can work with coordinate and BOM information as well as alternatively "just" set up a golden board comparison. The decision criteria for the inspection and the segmentation of the image comparison can be specified individually. With 7 different inspection types, EFA Inspection provides enough flexibility to adapt to different test scenarios. 

Shortly after the introduction of EFA Inspection, positive effects could be seen.

"The time required for the optical inspection went down like a landslide," says Mr. Linde, describing the first results of using EFA Inspection.

Instead of 8-10 hours of inspection time with 2 people, only one person with EFA Inspection needs 1-1.5 hours for an initial sample inspection. This means a pure time saving of 80-90% as well as a personnel saving of 50%!

The inspection itself takes place by means of a recording of the board. The high-quality images are created quickly and easily using the EFA Picture Touch device.

"Our wide range of components, designs and assemblies can be covered with the camera system in good resolution," says Mr. Linde about the recording quality.

The optimal lighting for each board can be individually adjusted using the touch screen computer. An HR version of the EFA Picture Touch devices is also available for circuit boards with particularly large dimensions. This creates several partial images per board, which are then stitched together to form an overall picture. 

The main focus of the 2D optical inspection is to verify the presence and polarity of the components. With changeable color settings, Hörmann has also been able to achieve a 3D effect that enables a solder joint assessment on the screen.

Profit for the whole process

Mr. Linde reports that the significant change in the optical inspection process impacts the entire production throughput process. Thus, Hörmann was able to optimize the throughput concept through closer integration of the production steps. In addition, EFA Inspektion virtually also offers traceability of the assemblies. 

The visual inspection has also improved considerably for the operator. A level of inspection, having all the information in one place and the 100% certainty of having inspected all the components or segments of the board effectively assist the examiner. This allows longer and more concentrated inspections. 

As an EMS service provider, Hörmann was also able to integrate the optical inspection of the circuit boards into the scope of services. The use of the semi-AOI solution guarantees a low probability of errors.

With this, "EFA Inspection is indispensable as a sales argument for EMS service providers in the small and medium-sized unit" segment, Mr. Linde underlines the all-round positive aspects. 

EFA Inspection is part of the EFA SmartSuite, an in-process LSE solution that supports the entire manufacturing process from pre-production to final inspection through dedicated applications. EFA SmartSuite is a "living" system, which has emerged directly from a wide range of customer requirements and is regularly expanded with new solutions.

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