CmController: A measuring system optimized for the special requirements of SMT production

CmController

The CmController is a universal measuring system for the investigation of machine capabilities, tailored to the special features of SMT systems. Its use enables the analysis and optimization of the accuracy behavior of the manufacturing process and the early identification of error causes. The results obtained in this way facilitate the planning of new products, the introduction of new technologies and help with investment decisions. Furthermore, the verification of machine capability is an important part of audits.

Possible Application

The manufacturing quality in surface assembly (Surface-Mount Technology; SMT) is decisively influenced by the positioning accuracy of the systems involved. Knowledge of this positioning accuracy enables us to detect any weak points at an early stage and to take appropriate measures. Ideally, this is done before product requirements are violated and the yield drops. This scenario is a classic application for statistical process control (SPC). However, a few special features of the SMT process have to be considered.

Surface mounting is a chain process in which the influences of different process steps overlap to produce an overall quality. The evaluation of the functionality of an electronic module at the end of the production chain is an attribute, i. e. the printed circuit board does work or does not work. On this basis, no information on the positioning accuracy of the systems involved in the process can be obtained (see also). Therefore, it is necessary to measure each individual equipment in a targeted manner.

The CmController makes it easy to use the advantages of statical process control (SPC) in surface mounting as well. It provides a quick and comprehensive statement on the accuracy behavior of equipment involved in the production process.
This allows us to understand random and systematic influences and to take corrective action if necessary. In this way, high manufacturing quality can be ensured efficiently and reliably.

x-y Plot of a measurement
Sample x-y-plot of a measurement. Outliers are clearly visible. The specification is not met.

Functional Principle

The measurements are based on high-precision glass measuring plates. These pass through the machine to be measured in the same way as a real product. For example, 0402 resistors are mounted on the measuring plate. The necessary machining program is individually adapted to the requirements of the respective machine type by means of the CmController software CmCStat. Detailed information about the procedure of a can be found here.

Powerful algorithms guarantee low measurement uncertainty and independence from ambient conditions. The measurements are carried out in the immediate vicinity of the system to be tested directly in production. This saves long distances and a special air-conditioned measuring room. Short measuring times allow a high sample size and thus guarantee a high statistical reliability of the results.

Single value plot
Example single value diagram. The outliers are caused by the results of a single nozzle.
However, the main focus is on problem-related analysis of the measured values. This goes far beyond the usual calculation of capability values and the determination of "passed" or "failed". While many systems leave the user in the dark about the reasons for a failing result, CmCStat supports the determination of error causes to the best of one's abilities. The software has extensive possibilities for statistical evaluation, grouping of measured values and graphical representation and thus allows an efficient and purposeful analysis of error causes. Because only if you know the causes of a bad result, you can take specific measures to improve it.

x-y Plot after error correction
x-y-Plot after error correction. The specification is safely achieved.

Advantages at a glance

  • Specialized in SMT requirements
  • Measurements directly in the production, no expensive measuring room necessary
  • Consideration of typical machine characteristics during planning and analysis of measurements
  • Evaluation optimized for finding causes of errors
  • Quick and detailed documentation of the results
  • Competent and well acquainted consultation with the measuring tasks due to extensive experience from our measurement service

We have developed the CmController for use in SMT production. New experiences, findings and requirements from our measurement service form the basis for continuous further development. Our wealth of experience in surveying thousands of plants helps you to efficiently perform your measuring tasks.

Technical data

  • Dimensions: approx. 600x620x1420 mm
  • Weight: approx. 120 kg
  • Working range: 300x200 mm
  • smallest uncertainty after GUM: \(U =\sqrt{1,00\; \mu\mbox{m}^2 + \left (6,50\; \mu\mbox{m/m} \cdot l \right)^2}\)