PCB News - About efficient data collection technology in SMT industry

Manufacturing companies in the 21st century are facing increasingly fierce international competition. Traditional methods to strengthen management through the implementation of MRPII/ERP are just a kind of black box operation, which can no longer meet today's complex and changeable competition needs. Therefore, how to make this black box operation transparent, find out any problems that affect product quality and cost, improve the real-time and flexibility of the plan, and at the same time improve the operating efficiency of the production line has become a concern of every enterprise. And MES is a very effective solution produced by the changes in production patterns over the past ten years. As one of the core industries in the 21st century, the SMT industry has yet to realize the popularization of MES. This is an opportunity. If MES can be widely used in the SMT industry, it will inevitably achieve a leap in production efficiency. At the same time, it will also be of great help to the improvement of quality and the saving of materials. The key of MES is to emphasize the optimization of the entire production process. It needs to collect a large amount of real-time data during the production process and deal with real-time events in time. At the same time, it maintains two-way communication capabilities with the planning layer and the control layer, receiving corresponding data from the upper and lower layers and feeding back processing results and production instructions.

1 SMT workshop data collection technology

The data collection of the SMT workshop is the basis for the establishment of the electronic circuit surface mount MES system. Through the collection of the SMT workshop data, the visualization of manufacturing data, data monitoring and plan tracking can be realized. At the same time, it is also a prerequisite for realizing abnormal alarm and production, quality information report query and other functions. The SMT workshop data collection technology emphasizes the integration with the equipment control system, and the second is to realize the real-time collection of production data. This requires technical research on data acquisition methods, parameter determination, software and hardware implementation, signal processing methods and other issues.

1.1 Basic functions that need to be implemented

The high-efficiency collection module that can provide data to the MES system. Its main purpose is to quickly, stably and effectively collect and centralize the real-time status of each device while saving costs and resources as much as possible. Features:

1) The existing main equipment of the enterprise is formed into an industrial monitoring network to realize the centralized monitoring of decentralized equipment; 2) The production parameters of each equipment are collected through a certain communication protocol or sensor, and the production process is monitored in real time; 3) When the production parameters are abnormal, Real-time alarm, and real-time feedback of alarm information to production managers and field engineers; 4) The data acquisition system is stable and highly reliable, and does not affect the normal operation of the original equipment.

1.2 Available collection methods

In the SMT workshop, due to the diversity of equipment, the data collection methods that can be used are: 1) Obtain signals from the equipment control system; 2) Obtain discrete analog signals through sensors; 3) Collect switch signals.

1.3 Key equipment and main parameters that need to be collected

The collection and sorting of manufacturing data of key equipment in SMT workshop is the basis for production planning, product history maintenance and other production management. The key equipment for data collection production and testing mainly includes: 1) solder paste printer; 2) glue dispenser; 3) placement machine; 4) reflow oven; 5) flying probe, X-Ray testing machine, optical AOI and other testing equipment.

2 Realization of automatic data collection

As far as the current key equipment is concerned, their operating systems include windows and Unix, and older equipment also have DOS systems; communication interfaces also include RS232 and RJ45, and even non-standard computer interfaces; data storage formats are also one-of-a-kind, There is no uniformity and coordination at all, and corresponding data collection methods can only be implemented for different types of equipment.

2.1 Obtain the required data directly from the equipment system

1) Interface communication method collection

In interface communication, the widespread use of GEM equipment is a big improvement. The SECS II (Semiconductor Equipment Communication Standard)/GEM (Equipment Communication Model) protocol is an industry specification drafted by the Semiconductor Equipment and Materials International Association (SEMI). Its appearance was originally aimed at semiconductor production equipment, so that control systems and equipment from different suppliers unified communication protocols, and equipment with GEM compatible interfaces can be easily integrated into the enterprise's MES strategy. At present, most of the equipment of most equipment suppliers on the market has a compatible interface that meets the SECS II/GEM protocol through a variety of expansion methods.

2) Obtain data files directly

Some other equipment, some have integrated the data collection function in its control software, can export the data content we need; and some are like flying probe, X-Ray test machine, optical detector, etc. For the testing equipment, the result of its operation is the data file, which needs to be manually reviewed. We can all network with the control computer of these devices, and use common protocols such as TCP/IP to transfer files to realize data collection.

2.2 Install sensors to obtain data

For situations where the first method cannot be achieved, we may use additional specific sensors to achieve the purpose of monitoring. The most common equipment that requires additional sensors is the reflow oven. Although many reflow ovens also provide GEM compatible interfaces, or can record their own temperature sensor data in real time, these temperature data only reflect the approximate temperature of each temperature zone, and the actual temperature of the PCB board in the reflow oven is still different. Differences, so the collected data cannot be used as a reference for production control. Therefore, the furnace temperature tester is produced as needed. The traditional furnace temperature tester installs the sensor on the PCB board, passes through the reflow oven along with the PCB board, and records the furnace temperature curve, so that a fairly accurate furnace temperature curve can be obtained, which truly reflects the real-time PCB heating process Temperature, but its method is too complicated and not convenient for real-time data collection in mass production. For example, KIC’s new product KIC 24/7 in the United States adopts a new method. The thermal sensors are installed on the PCB conveyor belt and distributed evenly. The 30 thermocouples installed in the furnace continuously monitor the temperature changes in the process. This change will be continuously displayed on the computer screen of the tester in the form of a process temperature curve, and the data will be recorded on the hard disk at the same time.

2.3 Collect the digital signal

The acquisition of digital signals is relatively simple. It only needs to record the on and off of some key lines to determine that the entire MES network is working well, including the normal operation of the equipment and the unblocked transmission lines.

3 Conclusion

Data collection is the key to the realization of MES. Effective and reasonable methods should be adopted according to the on-site environment of the specific workshop to conduct real-time data collection. However, the difficulty of data collection is the direct reason that restricts the development of MES in the SMT industry and causes the production efficiency to fail. Therefore, it is an urgent need to encourage all SMT equipment suppliers to unite and unify interfaces and data specifications. When data collection is as easy as searching for objects, MES can achieve real big development in the space of SMT, and the SMT industry is bound to usher in a new spring.