SMI layer

The right connection as the basis for success

The increasing globalization of sales markets leads to steadily increasing competitive pressure. The alignment of our own production structures and processes to the needs of the customer as well as quality assurance are becoming increasingly important. In order to counteract the cost pressure, optimization potentials are increasingly exploited through sustainable process improvements and possible errors in production are recognized and eliminated at an early stage. Keywords such as traceability, production management or quality data are omnipresent.

It is therefore a must for manufacturing companies to focus more on process-related manufacturing management systems (MES).

Figure 1: Automation pyramid

In the software architecture, these systems are located below the ERP systems and above the automation level (see Figure 1). While the ERP system has the entire company in view and enables logistical optimization across locations, the MES system is focused on individual production lines of a company.

In the best case, the MES system continuously collects all the operating data that arises along the material flow of these production lines and makes it available to the higher-level ERP system. In this way, complete traceability of products, components or batches can be ensured. With regard to the Product Liability Act, the basis is laid for documenting product development. However, optimization potential and process improvements can only be identified and exploited using this operating data. They are the basis of all decisions and are therefore of fundamental importance.

Order data acquisition using the example of an SPI system from Koh Young

But the variety of machines available on the market leads to a heterogeneous environment for machine integration. Not only the interface to the machine itself, but also its task in the production process require a differentiated connection. This should be illustrated using the case example of a solder paste inspection (SPI) machine from Koh Young. The Korean manufacturer Koh Young Technology has made a name for itself worldwide in the field of 3D solder paste inspection and has become a de facto standard. The usual procedure for controlling an SPI machine first requires the circuit board to be created using a CAD program. Using the extended Gerber format, the layout data of the printed circuit board are then exchanged between the CAD program and the SPI machine. The SPI software then uses this data to generate a job file that contains all the necessary information about the solder paste sites (pads) to be inspected. This job file is then the basis for the actual solder paste inspection (see Figure 2).

Figure 2: Loss of information during SPI job creation

In this process of creating the job file, however, information that is irrelevant to the actual SPI process is largely lost. This includes in particular information about the manufacturer of the electronic components, the type of housing used, the classification in libraries and much more. If such information is required for later analysis purposes of the recorded order data, then this must be integrated again later. As an integral part of a production line, the SPI receives the circuit boards to be checked from the material flow and then carries out the solder paste inspection using the previously created job file. The results of this inspection are then stored individually for each pad in locally stored databases (see Figure 3).

Figure 3: Processing of results in MIL

The amount of data generated per circuit board is directly dependent on the number of pads inspected and is usually very extensive. If any pads do not meet the specified limit values, additional image material is saved for later manual evaluation, causing the amount of data to increase again. The task of the Smart Machine Integration Layer (SMI layer) is now to make all required data from the inspection process available to the MES system. This data is obtained from the result database as well as from the job file. However, due to the immense data volume that arises per printed circuit board, extensive evaluations have to be carried out in the SMI layer in order to reduce the amount of data for the transfer to the MESSoftware layer to an acceptable level. This processing of results is of course dependent on the requirements of the MES layer. As a result, information that was lost when the SPI job file was created can now be required again by the MES system in connection with the result data. If this is the case, the Gerber data must be joined to the result data in the SMI layer.

The Smart Machine Integration Layer

The loss of information that occurs during the creation of the SPI job file and the enormous data volume that arises for each inspected printed circuit board require an intelligent interface to the higher-level MES system. This interface must have a modular design in order to meet the requirements of different MES systems (see Figure 4).

Figure 4: Modularization of the machine integration layer

Since the MES industry is a comparatively young software industry, the customer often still uses proprietary systems, which are often the result of in-house developments. Because of the lack of interfaces, it is often necessary to prepare results after the SPI process. But also the goals mentioned at the beginning, such as the complete traceability of components (traceability) or production management, require specialization of the connection software to the higher-level systems. Only by assigning a unique reference number for each system component through the ERP system can, for example, complete documentation be guaranteed during the manufacturing process. However, since these reference numbers are irrelevant to the actual CAD or SPI process, they must be merged with the results of the SPI machines as early as possible. The modular concept supports the integration of the additional data from the various ERP providers into the connection software.

The diversity of newer and older machines, on the other hand, has led to a heterogeneous integration environment that cannot be covered by just a few interfaces. In many cases, the interfaces are device-specific and far from industry standards, so that modularization for machine connection is absolutely necessary.

outlook

The steadily increasing data volume, the penetration of the system levels with additional information and the heterogeneous software and hardware environment of the customer require a modular connection of the machines to the higher-level systems.

Such a modular connection has been available for some time and has proven its worth in productive use. The exemplary connection to the Koh Young SPI machine was also used extensively and runs in the context of different MES systems. Thanks to the modular concept, customer-specific expansion is also possible without any problems, so that this connection was also used as a stand-alone application without higher-level MES and ERP systems.

The right connection is the basis for the success of our customers.

1ERP Enterprise Resource Planning

2MES Manufacturing Execution System