# Measurement Service for Determining Positioning Accuracy on SMT Equipment

## Determination of Positioning Accuracy for SMT Printers

• Determination of positioning accuracy for SMT solder paste printers
• Evaluation of the repeatability through a certain number of measurements
• Impartial and independent measurement analysis complying with DIN ISO 17025
• Diagnosing root causes of inaccuracies and deducting the offsets correction
• Validation of the offsets correction efficiency
• Improvement of the printing accuracy through fine-tunings of the printing offsets
• Calculation of $$C_m$$ and $$C_{mk}$$ Board to board values based on defined specifications
• Declaration of conformity according to given specifications in consideration with measurement accuracy and given target values
• Detailed und meaningful test report

### Preparation from CeTaQ

• CAD-Datas to create the printing program with consideration of the working area, typically 216x184,5 mm. This corresponds to our standard measuring plate MPL09 for solder paster printer.
• Calibrated Glass board used with the CAD-Datas
• Stencil
• SMT Glue to replace the solder paste.
• Mobile Measurement system CmController to perform the tests

### Preparation from Customer

• Validate and finalize the printing program from the specifications defined in the CAD-Datas.
• Guarantee a good state of the analysed machine through maintenance and eventually a calibration.
• Dedicated squeegee with the correct length
• Table and access to AC power socket close to the printing machine to install the measurement system.
• Technical support to operate and program the equipment.
• If necessary, some support tools which fits the glass board.

### Printing on the Glass Board

The equipment to analyse is prepared with the help of technical support. The dispensing program loaded and the glue supplied. Then, the glass board is loaded into the placement equipment. The machine validates the position of the glass board with the help of fiducial marks. Afterwards the first print takes place. Eventually, adjustments of the printing parameters are necessary. The objective is to get well defined round and repeatable deposits.

### Measurement of the Deposits

Once the glass board is populated with glue deposits, it is inserted in the CmController and the x,y positioning accuracy of the glue deposits will be measured. The measured position is compared with the nominal position. These datas are the basis needed for further analysis.

### Validation of the initial State of the Equipment

Both steps, printings and measuring are many times repeated. Aim is to judged the final state of the equipment during all prints and also for each print directions. In addition, numerical and graphical tools are available in the analysis software CmCStat. Beside the statement does not limit itself to a simple judgement like specifications reached or failed. Therefore, many detailed information are displayed to help in failure root cause analysis. For example, dependencies between offsets and nozzles or angles of placement are identified. This knowledge gives explanation on how the accuracy of the equipment can be improved.

### Use of the Results to Optimize the Accuracy

Based on the final state, some possible offsets corrections are determined. This are generally offsets depending on each printing directions for example.
Most of the times, those measured offsets corrections are adjustable in the machine software or directly in the machine. It allows, based on the measured datas to apply these corrections immediatly.

If mechanical causes are the reason for inaccurate printing, the measuring results can be used to identify the problem by ordering the sequence with groups. It facilitates the failure diagnosis for the maintenance service.

### Validation of the final State

When all corrections are made, a certain number of printing is done, as a rule 25 in total, without any changes in the equipment. These will determined the final state. The repeatability is calculated. The influences of inaccurate printed dots (bad shapes) on the result are thereby eliminated.

### Report Writing

Based on the reached final condition, a test report is written at the end of the evaluation. This is written usually in our office after customer visit. Beside the detailed description of the final results, it contains the history of the necessary steps to reach the final condition.

• Measurement system and dedicated glass boards are calibrated in conformity with DIN ISO 17025.
• The procedure is suitable for all type of solder paster printer.
• The required time for a complete evaluation depends on the type of equipment. As a rule it takes between 2 to 6 hours. Typically, the study takes around 4 hours.