The most commonly used method of illustrating yield is Parts Per Million (PPM) Defective. This provides a measure of the defect level against a process stage or a specific product compared against a known number of opportunities for defects to occur. There are IPC and IEC documents and procedures which do exist to monitor a process, which would be considered during the development phase of this project. Bob explained that SMART Group had offered their defect monitoring documents to the IPC in the early stages of the development of their two documents. In a recent SMART Group on-line survey it was highlighted that over 65% of companies use PPM monitoring.

It is hoped to continue to work with IPC and other organisations to provide one source for process comparisons rather than having fragmented projects in different parts of the world. Its also important the information is available to all companies and participating companies benefit from their contributions.

Although the methods and procedures do exist in a variety of sources, no co-ordinated effort has been made with small and medium volume assembly companies to assist and provide a reference on performance. With support for this project, process data collection can be simplified, a benchmark for each process can be defined and an ongoing reference provided to industry.

Training a group of staff in the data collection process used for PPM Monitoring and establishing process yield. This group would then be responsible for providing data once per month.

Confirm IPC inspection criteria for:

Solder paste printing
Component placement
Reflow soldering
Wave soldering

"Currently there is no inspection criteria for stencil printing in the IPC reference guides, however representatives of the IPC have been circulated a copy of a draft guide for comment. The document and inspection criteria will be used for this stage of assessment with any amendments" explained Bob Willis

Monitor a sample of boards from a batch currently in the assembly process to obtain the data to provide the initial average PPM levels for the website

Define the basic process parameters and materials used for assembly for future reference against the yield data

Define the technology level of the products inspected to allow companies to better understand the yield data. The technology level will be broken down into three classes.

Confirm confidentiality of data collection process

All the delegates agreed that the concept of data gathering was sound and 15 companies agreed at the initial meeting to support the project. A further two companies have subsequently offered to participate since the meeting.

The aim is to have the initial monthly average data available to the industry just after the summer period with presentations on the PPM Monitoring Project and results presented at Nepcon Electronics in October.

At the end of the meeting Bob Willis thanked everyone for attending and giving up their valuable time. "The need for a reference to yields has been needed for years and it's the most common question asked in our industry. Having produced the first initiative in 1994 I am pleased to see the industry support a project that can be useful, support our industry that supports us all".

Further information on the PPM Monitoring Project and how your company may participate can be obtained by email technical@smartgroup.org