Initial sample inspection - more than just optical inspection

EMS providers constantly face new dynamic customer requirements. With changing products, ever new component requirements and variable batch sizes, there are constantly growing demands on our own production processes. The quality of the manufactured products is ensured with a large number of controls. The following applies: The later an error is detected during assembly production, the greater the work required to eliminate this error. In order to save time and money, the use of the most comprehensive initial sample inspection possible, as is possible with the EFA Inspection solution. This does not only mean pure optical controls, but also the control of the data and the verification of the physical component values.

EMS provider Sumida Lehesten

In order to be able to reflect the high quality of the products in the future, even with changing framework conditions, the company's own production processes are repeatedly put to the test. At Sumida Lehesten from Thuringia (Figure 1), continuous improvement management is part of the high quality understanding. The company, founded in 1965, produces high-quality products for applications in entertainment, automotive and industrial electronics with around 300 employees on 5 SMT lines at the Lehesten site. As a full-service provider, Sumida Lehesten relies on long-term customer relationships. In addition to quality and environmental certification, the company has also had an IATF 16949 certificate since 2004. In order to meet the flexible, customer-specific requirements at the highest level of quality, all manufacturing processes are geared towards zero-defect production. In 2018, Sumida Lehesten was looking for suitable solutions to optimize the process of the initial inspection.

Initial sample testing requires a high level of testing depth

Due to the high level of flexibility that characterizes an initial sample inspection, it is often carried out manually. Automatic systems focus only on the visual control and can also not inspect without time-consuming programming. The EFA Inspection solution, on the other hand, combines flexibility and time savings.

In order to meet the required test depth, Sumida Lehesten compares the component data in its own parts list with that of the customer and combines the LCR measurement with the optical inspection in the same test step. Since many components do not have a label, only an electrical measurement can confirm the correctness of the component.

The established testing process also required a high level of concentration from the employees at Sumida Lehesten. A lot of time was spent looking for the components on the circuit board and in the documents. The documentation of the individual test steps was done manually. The measured values themselves were not recorded. A calculation operation had to be used to check whether a measured value was within the expected tolerance range. The test itself was difficult to understand.

To improve this process, Sumida Lehesten was looking for an effective inspection solution that combines optical control as well as LCR measurement and data control. The company LEBERT Software Engineering offers exactly such a system. After a short evaluation phase, the EFA Inspection system was introduced at the end of 2018.

Augmented Reality Inspection

The inspection system EFA Inspection can be flexibly adapted to the respective purpose. The type of inspection process depends exclusively on the current process. For the initial sample test, all components to be tested, e.g. Display e.g. grouped by part number. The presence of all components for each part number can be seen at a glance. (Figure 2) The polarity check is also possible at a glance, as EFA Inspection shows the individual images rotated to zero degrees in the overview. This means that all polarity markings must be in the same place in the overview of the components. Important component information, such as component values or manufacturer information, is displayed directly on the associated component. If the customer's data and one's own parts list are combined here, this comparison is also possible at a glance.

Integration of the LCR measurement

The existing LCR measuring device was connected to EFA Inspection for the interlinking between the optical inspection and the LCR measurement. The measuring device is controlled automatically directly from the software. The measured value is transmitted to EFA Inspection, compared with the tolerance range, automatically evaluated and documented.

EFA Inspection significantly simplifies the inspection process for employees. The program guides you through the inspection and displays the components with the relevant information grouped by part number. At the same time, the first component of a part number for the LCR measurement is located.

“Working with EFA Inspection saves a lot of time. In addition, we have all the information ready immediately, ”was the verdict of the employees from the test field.

Of course, individual test reports can be generated after the test has been completed.

Recognize every detail with up to 5000 dpi

The inspection is based on a high-resolution image of the assembly. In order to generate these reliably, Sumida Lehesten decided to use an EFA Picture device. (Figure 3) The camera-based recording device generates microscopic overall recordings of the circuit boards. The parameters of the device can be flexibly adapted to new recording situations. Depending on the requirements, recordings with a resolution of up to 5000 dpi can be created through individual setting options. (Figure 4)

For this purpose, several partial recordings of the assembly are created, which are added together to form a total record. The algorithms of the specially developed software EFA Stitch take into account both different exposure situations and perspective imponderables.

Profit for work preparation

The technical work preparation also benefits from the simple data preparation and the possibilities to easily combine placement data, parts lists and placement plans. EFA Inspection supports the preparation of the initial sample inspection with automatic processes. In this way, the values for the LCR measurement can be automatically taken from the imported parts lists.

“So far, we have been able to import all different customer formats in EFA Inspection. The purely digital preparation for the production and the tests has become significantly more reliable and enables a completely new view of the customer's product, ”confirms Mr. Stöhr from the technical work preparation.

Originally acquired with a focus on initial sample testing, the solution is also used, among other things, for quick process approval in the event of restart. Sumida Lehesten is also currently reviewing the use of other functions of the software solution. The possibility of searching online from EFA based on material numbers or physical component values is interesting.

Smart solution established

Sumida Lehesten benefits from the introduction of the EFA Inspection inspection system.

“Overall, an improvement in the affected processes was achieved through significant time savings. In addition, the system enables faulty equipment to be found reliably and thus contributes to general process optimization, ”explains Mr. Stöhr.

At the same time, the documentation and the traceability of the initial sample inspection process has been significantly improved.

In order to meet the steadily growing demands on the EMS industry with smart software solutions, LEBERT Software Engineering started developing EFA Inspection for fast initial sample inspection in 2009. In the last 10 years, EFA Inspection has created a whole suite of smart software solutions. Right from the start, the development draws on the experience of a large number of EMS providers. The EMS software EFA SmartSuite thus offers efficient solutions for many process steps from the preparation of the offer to work preparation to production. In particular, processes can be made easier again and again that combine human know-how with the automatic system of the computer - and thus save people significant time - entirely in line with Industry 4.0.