2005 Articles

Knowing your pre-audit needs can save time and costs during the site visit.

Introduction of Pb-free technology involves every department in your company. Each engineer should understand the implications of Pb-free – even those exempt from existing legislation. Indeed, companies that are exempt cannot ignore the implications. As industry changes to meet the July 2006 deadline, components, materials, bare boards and service industries that support you will also change their products and services. If you are going to conduct a technical assessment on an internal or contract production facility, prepare a basic plan to add structure to the project.

Let us consider some of the basic points and information that should be obtained prior to the audit to help rank potential suppliers. Often only one or two days are spent visiting each supplier and the time can easily be consumed with company presentations, lunch and less important issues. Avoid wasting time: don’t be afraid to set your own agenda. Time can often be spent more valuably by reviewing materials in advance. It may also help to reduce on-site visits. Any good contractor will be able to supply this information for review. Sales and marketing executives will know the benefit of creating the right feeling of professionalism and technical awareness.

Also consider what your potential supplier will need from you. They would like to know about your products, volumes, when production will start and what has been done to ensure your build of materials is compliant with WEEE and RoHS. Remember: Any project should work as a partnership, with information flowing both directions. 

Company information. General information on the company, location map and contact details, email, telephone, mobile and fax numbers for key contacts. Having the information allows coordinating the best timetable for travel and accommodation. This information may seem obvious, but often is not provided prior to the visit. After reviewing information on the company there may be additional information that you may want in advance. This all helps to assess the company’s responsiveness.

Production equipment. List of production equipment and its capabilities for Pb-free processing should be available, with supporting documentation and test reports to demonstrate existing Pb-free capability. Many companies say they have Pb-free capability but often lack much practical experience. It’s fair to say that there are few Pb-free products being built today, but this is about to change quickly. There are many ways of gaining experience in Pb-free and it is important that all staff have some practical hands-on experience.

DfM/design review. Get a sample of the Pb-free design requirement/customer DfM/NPI report for new products. Obtaining an example report or a template in advance permits an understanding of the detail of information gathered on a pilot build. Often, some of the minor comments become significant problems in medium and volume manufacture. Previous customer reports may be confidential, but the format and template of points normally covered should not be. If the feedback is not structured (e.g., just a long list of emails), items can be missed, or some staff can be left out of the feedback cycle.

Assembly process. An assembly flow diagram for conventional and mixed technology products should reveal to auditors the process their product will undergo. It allows auditors to focus on key stages and highlight any obvious omissions in their requirements. It also provides a good reference to check on equipment upgrades and changes for Pb-free, plus the company’s documentation and procedures. It will provide assistance if there is a key stage that the product or components require, such as additional moisture protection for parts (a critical item for Pb-free).

Inspection and process control. Inspection criteria/process control requirements for each assembly stage in manufacture should be provided with all key control stages in Pb-free manufacture. Look for evidence of inspection standards on the shop floor and examples of process monitoring results to backup any information in your pre-visit documentation. On site, talk directly to operators and technicians about issues they have experienced with Pb-free to see how it matches with your experience. Often, staff have not actually seen the documentation that they are reportedly working to as it has not been released to manufacture.

Process materials. A list of soldering and cleaning materials used in production, and the suppliers (with product reference numbers) should be provided, and updated when they change. Companies that use multiple subcontractors or a single in-house assembly facility often debate variations in quality, visual appearance and cleanliness when what’s really showing up is the incompatibility of materials. There should also be some documented evidence of Pb-free trials conducted on the materials and the results; this should show a structured approach.

New process or equipment. A list of future equipment purchases or upgrades for Pb-free, including their scheduled introduction dates, should be obtained. A copy of the company’s technology roadmap should list each of the process changes. It is also worthwhile asking for roadmaps covering the past two or three years, to see if proposed process changes were completed and on schedule. It is fair to say that for most medium- and high-volume companies changes to most equipment should not be required as high-end machinery is already installed. For smaller companies that may not be the case. Issues of availability may be a problem in the near future. Suppliers of wave-soldering upgrades/retrofits may not be able to cope with demand of Pb-free conversion, for example.

Training and education. A list of training modules and content should be reviewed for production staff, engineering, quality, purchasing, sales departments, as well as assembly, design and PCB technology. If an extensive Pb-free training schedule is underway there may be an opportunity to partner with your potential supplier so that your company can benefit. During a recent project in China, a contract assembler was training employees in Pb-free materials process control and WEEE and RoHS at a rate of 50 per week.

A record of the specific training, topics and the employee’s achievements should be available for review. Attending training sessions is beneficial but achieving some level of proficiency must be the goal. Documented tests, pass marks, successes and failures should be documented so the training courses can be updated, reviewed or strengthened.

External services. A list and location of any processes, test and environmental assessment or defect analysis not conducted on-site should be available, plus evidence of their own audit results. X-ray inspection, conformal coating and investigative services like microsection and failure analysis are often conducted offsite. Each EMS should have a plan for subcontracting to other suppliers, if required. It is then necessary to get additional information on their services and capability. A contractor may vet other service providers, but it the customer’s responsibility to make sure these third parties meet their requirements.

At the end of your assessment a short report should be produced covering strengths and weaknesses of the suppliers, with a scoring method employed to rank the companies. You should allow time after your visits to explain your findings and decisions to potential suppliers. Auditors often forget this step. But you don’t want a supplier thinking you have wasted their time, in case you should want to re-evaluate a supplier in the future.

Here are some of the interesting comments that I have received during my audits (readers can draw their own conclusions on my responses).

• “All the information will be provided during the visit” (Au note: It’s not and time is wasted during the visit).
• “Our Pb-free engineer is on holiday, we can’t provide the information.”
• “We don’t have the information available in English.”
• “We will provide the information when you place the order.”
• “All the information is on the Web site” (Au note: No links are provided or it’s not on the site).
• “We don’t monitor our process stages or rework; only our final test results.”
• Detailed information package of hard and soft information was provided, but conflicted with all the information seen during the visit.
• “We can’t provide that information, it’s confidential.”

Bob Willis is a consultant, instructor and founder of leadfreesoldering.com, which provides support in PTH and surface mount Pb-free assembly processes; bob@leadfreesoldering.com. He is producing a Pb-free Interactive Forum at Productronica in November.

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