PPM/DPMO - Monitoring - Monitoring Procedures

PPM AVERAGES
Solder Paste Printing:
Component Placement:
Reflow Soldering:
Wave Soldering:

The symbol:

indicates that a video clip is available on this page. To view the videos you will need a copy of Real Player installed. You can download a free version by going here: Real Player Website

INTRODUCTION
This procedure is being used for monitoring the PPM Parts Per Million defect levels in the four assembly stages. Basically sample boards are taken after each of the assembly stages and inspected to the requirements of IPC 610 level 3 and the IPC 9261 (In Process DPMO and Estimating Yield for PWAs).

Where visual criteria do not exist reference documents are provided on the web site to download. They cover for solder paste printing and intrusive reflow assembly and soldering.

The average defect levels for each of the process stages will be calculated and provided each month for comparison on the web site. To obtain the results from all the contribution companies, process used and technology levels you need to contribute to the project for a minimum of two months.

A spreadsheet is also provided for download to record the defect opportunities, inspection results, process information and the technology level of the product being assessed. A guide to the technology level of the printed board assembly is also available to download with the process spreadsheet. Both reflow and wave soldered product designs are graded 1-3 to aid comparison with the final PPM yield data.

The interactive online data recording sheets are available in the Members Area for companies contributing to the project.

All the information is held by the project co-ordinator and is not made available to any other company. The information presented on the website to participating companies is not attributed to any one company and is shown anonymously for comparison.

Inspection is conducted at the following stages in manufacture by each company:

MONITORING REQUIREMENTS

SOLDER PASTE PRINTING
A minimum of 5 samples boards or panels are taken for visual inspection. Any company can take a much larger sample if they wish. The minimum number of 5000 opportunities are to be taken which may require additional boards or panels to be inspected if the minimum number of opportunities is not achieved. The opportunities for error to be determined are based on the stencil apertures printed in the samples.

Printing Defects x 1,000 000 = PPM Level Opportunities

COMPONENT PLACEMENT
A minimum of 5 samples boards or panels are taken for inspection after the final component placement prior to reflow. The minimum number of 5000 opportunities are to be taken which may require additional boards or panels to be inspected if the minimum number of opportunities is not achieved. The opportunities for error to be determined are based on the number of components placed on the printed board samples.

Placement Defects x 1,000 000 = PPM Level Opportunities

The defects considered after placement are not limited to misalignment they may include missing, reversed or damaged components. Reference should be made to the relevant sections of IPC 610.

PPM/DPMO - Monitoring - Monitoring - Component Placement

REFLOW SOLDERING
A minimum of 5 sample boards or panels are taken for inspection prior to any rework. The minimum number of 5000 solder joint opportunities are to be taken which may require additional boards or panels to be inspected. The opportunities for error to be determined are based on the number of reflowed solder joints produced in the sample.

Reflow Defects x 1,000 000 = PPM Level Opportunities

The defects considered after reflow are not limited to solder shorts or opens; they may include insufficient solder balls, damaged components etc. Reference should be made to the relevant sections of IPC 610.

PPM/DPMO - Monitoring - Monitoring - Reflow Soldering

WAVE SOLDERING
A minimum of 5 samples boards or panels are taken for inspection prior to any rework. The minimum number of 5000 opportunities are to be taken which may require additional boards or panels to be inspected. The opportunities for error to be determined are based on the joints which are wave soldered in the sample.

When the number of wave soldering defects have been determined the PPM level is determined.

Wave Defects x 1,000 000 = PPM Level Opportunities

PPM/DPMO - Monitoring - Monitoring - Wave Soldering

The defects considered after wave soldering are not limited to insufficient solder penetration and solder shorts; they may include lifted parts, solder balls and SMT solder skips. Reference should be made to the relevant sections of IPC 610.

The inspection results from the process and number of sample boards or panels are also to be recorded for each stage. The number of defect opportunities and actual defects are to be recorded.

CALCULATING PPM/DPMO

If there are any questions on the expanded procedure on collection or calculation of the defects or you would like to take part and benefit from all the additional results please contact Bob Willis, SMART Group PPM Monitoring Project Co-ordinator info@ppm-monitoring.com

For further information on the SMART Group Europe's largest surface mount and related technology group visit www.smartgroup.org

top

For further information on PPM Monitoring and this SMART Group initiative, contact:
Bob Willis - info@ppm-monitoring.com