Measuring Systems with High Accuracy and Work Speed


Paul Semenov, Head of Automation Lab, R&D Center at Proton-Electrotex

Nowadays the spheres of power semiconductors usage are enhancing. Along with the production development and new types of power supplying the requirements for load capacity of power semiconductors are rising.

Introduction

The goal of meeting the requirements demands the joint power semiconductor usage in high loaded electric circuit, which in its turn defines special requirements for major characteristics measurement accuracy, as well as reliability and capacity of measuring equipment. For the purposes mentioned engineers of Proton-Electrotex automation laboratory have developed the line of measuring systems, which comply with the most demanding accuracy and work speed requirements, providing the high level of flexibility and work convenience for all users from operators and maintenance services to technicians and quality engineers. 

Equipment description

Measuring equipment represent module systems. According to the necessities it is possible to configure the system as both manual and automated measuring post. The basic features of module principle are represented below: 

  • Module design allows to configure the equipment for purposes of a certain task, combining the necessary units into one measuring system.  Such approach allows to reduce organization measuring process costs, as there is no need in purchasing the broadband laboratory measuring device, and additionally the opportunity to use the perfectly matching equipment.
  • Simplicity and economic efficiency of building-up. Power capacity as well as the spectrum of measurements might be increased as a consequence of using module design and applying new units. Hereby the equipment might be easily configured according to the altering demands of the measuring process. Let us admit the necessity of adding new and enhancing the range of existing parameters. The reason for such a necessity might be in the launch of a new product or equipment. Modular measuring equipment allows to connect new measuring units to already existing systems. Consequently, the cost reduction connected with equipment modernization exists. 
  • The third critical feature is the maintenance simplicity. This feature is particularly relevant when organizing automatic flow measurements, as the process stoppage may lead to enormous losses. Module structure allows to reduce the repair simply up to scale of whole serviceable unit replacement. The time of unproductive time loss will be substantially reduced. For instance, there is time for carrying out the maintenance of some units.  The sequence of maintenance actions would be: stopping the production line, dismantle the required unit, connect the temporary unit and proceed to the production process. The system possesses the opportunity to remain functioning with disconnected units. Due to this feature the launch of the equipment  is possible within 1 or 2 hours upon condition the stock units have been installed. The replaced units are subject to diagnostics. 

Currently the following set of measuring units has been designed and implemented in order to meet the requirements for available acceptance tests measurements:

  1. Static losses measurement unit. Measuring current up to 12.6кА
  2. Blocking characteristics measurement unit. Current up to 8000V, current creepage up to 500mА (power semiconductor up to 65 class)
  3. Drive gate characteristics measurement unit.
  4. Isolation resistance, cathode-anode resistance, isolation dielectric strength measurement unit for 6 kV AC/10kV DC at current 10 mA.
  5. Critical rate of rise of direct voltage measurement unit. Up to 2500V / µs, up to 4500V (power semiconductors up to 65 class)
  6. Reverse recovery charge measuring unit
  7. Surge reverse power dissipation measuring unit 
  8. The measuring system is equipped with additional measuring units which provides more simplicity and convenience:
    1. Interface unit.  The unit is equipped with a 17 inch sensor unit which provides the convenient computer interface with the opportunity to adjust the measuring and analysis process. 
    2. Commutation unit allows to conduct all measurements at once – as high voltage measurements as high current. 
    3. Stable circuit voltage unit. Allows to level down the circuit power supply noise impact on the measurement process. 

The special equipment has been developed for design tests for surge current up to 120kА.

Measuring units for IGBT measurements for both static and dynamic parameters at the stage of industrial tests. 

The manual measuring workplace consists of the measuring equipment with connected clamping device. A huge variety of clamping devices applicable to various types of measured components allows to choose the optimum option for particular customers demand. The most technically complicated devices are the clamping devices with electro-mechanical drive, which allow to generate force up to 150kN and heating up to 200° C. The measuring system and clamping device are mounted in the 19" racks . The work place of the operator is the clamping device and measuring system equipped with heating and cooling systems. Human-machine interface unit and special table console provide the ergonomics of operator's workplace of the highest level.

In case of automated line the clamping devices are set up in a row in front of three-degree-of-freedom manipulator which moves the devices measured between the measuring stations. The automated parameter control system (code name ATSM) for module devices is currently put into operation. This system allows to conduct the measurements at the room temperature as well as at maximum junction temperature. Both measurements are carried out sequentially in different clamping devices which allows to get all range of characteristics for one run through the measurement system. Besides, the insulation resistance measurement are carried out. The main benchmark feature of ATSM is the automated valid devices marking. As a result the devices are identified unambiguously as a result of the measurements at ATSM, and the probability of faulty devices being dispatched to the customer is reduced to zero. The operator’s task is to load a lot of devices into ATSM and unload measured and marked devices. 

The infrastructure of information measurement system. 

The infrastructure of information measurement system represents the distributed network solution. Every measuring system is connected to the corporate network with the host server.  Measuring systems cooperate within the network and pass the data to the hosting server and receive configuration and measurements profiles. 

In order to obtain a complete understanding of a system it is recommended to begin with the description of the operator’s work in conditions of manual measurement activation. The operator receives devices which is required to measure. Using the bar code scanner the operator enter the measured devices type. Measuring system requests the measurement parameters of measurement profile for the type entered at the host server.

 Then the operator enters the unique code for the measured device with the help of sensor display or scanner, loads the device into the clamping device and presses the “start” button. All measurements are carried out complying with the measurement conditions in a completely automated mode. The results are saved and then are transferred to the host server for storing in the central database of the information measurement system. The operator’s only duty left is to unload the measured device and then to put next one inside the clamping device.

At first sight the whole procedure looks pretty simple. Though if the question of how the work of operator has become so simple and how the possible mistake was led down to zero, then the question of measurement profiles arises. These profiles have to be designed for all possible types of devices and their modifications in accordance with technical conditions and special additional requirements. Measurement profiles should be maintained properly to stay valid. Let us imagine that the enterprise puts not one or two MME but five or ten of them into operation. The issue of maintenance and adjustment becomes then the significant challenge. However this could be solved by the information system infrastructure easily and effectively. The maintenance service engineers at their workplace which could be any PC connected to the corporate network launches the managing software and carry out the centralized adjustment and changes the measurement profiles. Such software provides the opportunity to change existing profiles, creating new profiles, searching for available profiles. For instance there is no need in having access to profiles for stud devices at the MME for disk devices. More than that, in such a software the security policies might be set up for regulating the access of different operators to different systems. The sufficient opportunity for integration between the host server and various information systems like ERP systems, which could provide the data for measurement profile compilation. 

We have observed the technical aspect of measurement tests process concerning minimum level of human error.

However that is not the first priority goal for such information system of measurements structure, as the main goal is to obtain and analyze the measurements’ results. As it has already been referred to higher the measurement results are saved automatically in the central database. Upon completion of measurements the operator has an opportunity to print the test measurement protocol for a particular lot on demand. Additionally to that, the special software could be used for the demands of technological and engineering departments. All measurement test results will constitute interest for technologists in order to analyze these data through the time range. Such analytical software might be launched using any PC connected to the corporate network. This software gives an opportunity to draw various reports, slicers on different options: time ranges, lots, types of devices. Using these reports and slicers it becomes more effective to monitor the stability of production process. These data might a source of SPC or other intellectual data analitics using the neural networks and fuzzy logic. The data might be exported into the third party software. Among other features software allows to prepare and print any types of test protocols, required by customers or producers. The opportunity for integration of the centralized database with the corporate website is substantial for convenience of clients, as they would be able to obtain true and precise parameters of a semiconductor device using its serial number. This feature is also applicable for those customers who are designing the devices using semiconductors as components. 

The automated measuring systems are much easier to be operated as the operator only has to load the batch of devices into the automated system and unload the measured and marked devices.  All other processes are conducted fully automated yet likewise in manual mode.

Conclusion

To summarize it all mentioned above, the equipment designed and produced by Proton-Electrotex automation laboratory satisfies the demands of a wide segment of customers. Modularity of equipment allows to match and configure the measurement system satisfying the most modest demands. Usually companies which are servicing and conduct maintenance of the semiconductor containing equipment demand for such systems. Infrastructure of information system of measurements allows to match and configure huge and automated systems, applicable for medium and large semiconductor manufacturers.
Additionally to the above we need to claim that Proton-Electrotex has initiated the process of mobile low- power measurement systems development for field use and in 2017 the first market samples will be available. 

More information: Proton-Electrotex    Source: Bodo's Power Systems, January 2017