Our thanks to Conformity Magazine Published in December 2004 issue
http://www.conformity.com/0412enhancing.html

Accurate process evaluation provides real answers

Provided by the ESD Association
by Stephen Halperin, in collaboration with Ron Gibson

“We need to spend HOW MUCH?”

Recently, a company experienced several large losses due to electrostatic discharge (ESD) and had a very unhappy customer on their hands. The manufacturing vice president now faced a substantial expenditure for new ESD loss prevention equipment. The company’s first step had been to hire an ESD consultant who recommended the purchase of several thousands of dollars in ionization equipment and monitoring instruments for several of the company’s facilities.

The troubled VP read the report several times looking for justification of the expense. However, the report did not define how the recommended equipment would meet the VP’s specific needs. Other than describing how ionization reduced electrostatic charge after it is generated and that the instruments could confirm that a discharge occurred, the report did not identify the actual cause of the process problem. No ESD measurements were described. There were no details related to cause of product loss, device sensitivity concerns, value issues, process and handling details, examination and description of existing controls, or rationale for how the recommended tools would solve the problem in question. The report was clearly based on the consultant observing the process of a single manufacturing environment. In effect, the report made a purchasing recommendation based on a “blanket” opinion, not on facts specific to the needs of the company or their customer. Such an approach typically makes a bad situation worse. While the recommended tools may have been very useful for investigating a process or for solving defined problems, they are expensive Band Aids“ when used in undefined problem situations.

Today’s electronic manufacturing environment demands that minimal ESD controls be in place to provide fundamental protection for electrostatic discharge sensitive (ESDS) devices. When basic ESD controls are employed and losses still occur, manufacturing and quality managers face more difficult problems., In assessing the problem, companies struggle with a variety of major questions concerning a specialized technology, while having minimal information and available skills. To avoid the risk of making the wrong investment decision without solving the initial problem, management needs a way to select and implement the most effective ESD controls that fit their financial situation, solve their specific problems, and provide a respectable return on their investment.

 Why bother with ESD; what’s the big deal?

ESD control, other than a dramatic increase in sales, is the single most profitable opportunity for industry under today’s economic conditions.1 Independent consultants have found that ESD costs the average electronic manufacturer 4 to 8 percent of total annual corporate revenues, depending on product designs and device sensitivity.1 Internal studies in telecommunication and other electronic firms have revealed losses equal to, or in excess of, 10 percent of annual revenues.1 At an estimated average impact of 6.5 percent of revenues, this means the international electronics industry is losing in excess of $84 billion (USD) every year based on production data from 1997 through 2001.1

When faced with this information, a manager might exclaim, “This can’t be possible. If we lost this much money we’d be out of business.” That would be true if these losses were in addition to current operational costs and profitability. Unfortunately, all of these ESD related losses are included in current operational budgets. Electronics industries are losing literally tens of billions of dollars each year due to ESD, and most organizations plan for these losses, allow them to occur, and budget for them. Therefore, effective ESD controls can make a significant impact on profits.

Seeking Balance: ESD Control Costs Versus Benefits

How can we avoid the problems our VP was facing when addressing ESD controls and program development? How can we identify our specific problems and develop the best ESD control program for the lowest cost and maximum return on investment? Let’s explore these issues in greater detail.

All of us share the same objective: achieve effective ESD control that eliminates or minimizes damage and product loss while enhancing quality, productivity, and profitability. If we meet the objective in a manner suitable to our products and process, our returns are typically far greater than the cost of implementation. In a well-designed and balanced ESD program, history tells us that within the first year we can expect a minimum of five dollars in return for each dollar invested in ESD controls. Often returns are hundreds and even thousands of times the original outlay. But, how does one actually achieve this objective and generate a return on the investment? The following steps are an effective beginning for meeting these goals:

1. Understand the specific manufacturing process thoroughly

2. Hire or train personnel who understand the process and have ESD expertise

3. Select and implement ESD controls that meet the specific needs of the process and the devices being handled.

Understand the process. Even the most difficult ESD-related problems are fairly basic and can be resolved using a classic analytical approach—first define the cause of the problem then identify a suitable solution. A thorough assessment of the manufacturing process critical path, procedures, control materials, and environmental factors will either identify the cause of specific ESD problems and indicate suitable controls, or confirm that a problem does not exist. The keys to effective ESD analysis involve understanding the manufacturing process and products, knowing ESD analysis techniques, having an insight into the company’s or customer’s needs, and knowing the variables that affect them. Unfortunately, most organizations do not have ready access to experienced ESD technologists who have a clear understanding of all these elements.

As part of the evaluation, one must remember that every situation, facility, process, and work force is different. Some products are expensive and may be used in critical, sometimes life threatening or saving situations. Other products are low cost or have little critical impact to the user. Everyone’s problems are different, and the consequences of these problems span a huge spectrum of application impact.

Assessing the Process: An Illustration

There is a significant difference between simply installing ESD controls and hoping for the best and evaluating an environment for what is needed prior to specifying product purchases and installation. For example, consider a person generating body voltage by walking or moving within the environment. If that excessive body voltage is discharged to a sensitive device, there is a chance that the damage threshold of the device will be exceeded, possibly resulting in catastrophic ESD damage or partial degradation (latent damage) to that device.

Before recommending a variety of ESD prevention controls, an ESD specialist would determine the probability of personnel damaging a sensitive device during handling and transport. A series of measurements in the facility using readily available instruments and standard test methods (e.g., ESD STM 97.2-1999, ESD STM 97.1-1999, ESD STM 7.1-2001, etc.) would answer several questions.

Once these fundamental measurements were completed, a variety of calculations would be performed and the results would be compared to the Human Body Model (HBM) damage threshold of the most sensitive device in the process. This assessment would address the following concerns:

1. What is the probable range of body voltage generation during transport of sensitive devices through the process?

2. What is the probable range of body voltage generation while working at an assembly machine or standing at workstation and handling sensitive devices?

3. What is the probability of equaling or exceeding any given HBM damage threshold during handling and transport?

4. Is there an actual or potential problem when handling or transporting these devices in this process?

5. What is the most effective means of handling and transporting sensitive assemblies in the existing environment without ESD damage?

6. What process modifications would enhance ESD protection and expedite the flow of products through the environment?

7. Which modifications, if any, would be financially most beneficial?

Depending on the product value, criticality, and other operational requirements this assessment would help determine if ESD controls are necessary and to what degree. If an ESD problem does exist a return on investment can be calculated. A similar assessment, albeit more complex, can be performed on automated assembly and processing equipment.

Those individuals who perform the process analysis and select the ESD controls must have a clear understanding of the manufacturing and ESD universe. The ESD programs they design should be in harmony with process needs; they must select ESD controls that are adequate, but not too profuse or demanding for the operation in question. The selection and mix of ESD controls and procedures should be well balanced for the operation’s requirements. Next, let’s look at the people who should perform the process evaluation.

1. Hire or train personnel who understand the process. So, what is one of the most effective ways to solve a variety of ESD problems and do so profitably? Start by using trained ESD practitioners to assess your process and maintain your ESD control program. There are three sources for obtaining trained personnel to assess and maintain your facilities.

2. Train selected company employees. A current employee who is familiar with the process can be trained as an ESD program manager. This may require additional education such as the ESD Association national and regional tutorials and professional certification educational programs. There are also experienced ESD consultants who conduct private seminars, in house training, and public seminars.

3. Hire ESD practitioners trained by other organizations. Many corporations have made substantial efforts to develop in-house ESD expertise. During the past few years, personnel cuts have resulted in many of these individuals being laid off, or retiring. Many have either moved to other organizations or are looking for new situations.

4. Use contract services provided by professional static control (ESD) service firms. While several are available to service your needs, seek those who are experienced and well qualified. Many ESD consulting firms have websites, and a basic “search” will locate several for your consideration. Most professional ESD advisors are members of the ESD Association. While membership does not necessarily guarantee results or technical knowledge, it does indicate an interest in the ESD industry and its technical and standard developments.

Regardless of where you find qualified expertise, the successful ESD practitioner has a fundamental background and knowledge in identifying and solving ESD problems. Furthermore, when it comes to establishing a certifiable ESD control program, e.g., ANSI/ESD S20.20, an effective ESD advisor has clear and objective understanding of the client’s actual control needs, rather than a “packaged” approach for controlling only those elements that are important to the advisor.

Having consulted in the ESD field since the late 1970s, and having trained many ESD practitioners, we find that successful ESD specialists have skills, knowledge, and experience in common. For example:

1. They have worked in technical environments and have process experience in the manufacturing of complex products or materials.

2. They have a sound understanding of ESD theory and associated measurements.

3. They can relate the theory to ESD sensitive processes and environments in a manner that clarifies the problem’s cause and process needs.

4. They can transform the client’s specific needs into a tailored ESD program.

5. They are capable of performing an in-depth assessment of a process, and have a full understanding of the risks and ESD problems before making a recommendation for control.

Select and implement ESD controls. The next step is to select the right controls from a variety of available ESD products, materials, devices, and “tools.” The “right” controls for the large manufacturer of expensive medical life support equipment may be far more extensive than those used by the small manufacturer of low cost consumer products. Interestingly, they must both meet the same objectives, but they may do so in different ways, with differing levels of redundancy.

Effective ESD control requires that the process interaction between people, equipment, materials and devices:

1. Generate static charge at a level that does not exceed the damage threshold of the most sensitive device in the process;

2. Readily dissipate generated charges to ground and maintain all devices and process elements at the same potential;

3. Use protective packaging when sensitive items are stored in, or transported through uncontrolled areas.

These requirements can be met by adhering to the three fundamental principles for developing an ESD control program in accordance with ANSI/ESD S20.20:

1. Ground/bond all conductors.

2. Control charges on all non-conductors.

3. Use protective packaging for transit and storage.

A basic set of ESD controls may consist simply of (1) a static controlled worksurface, (2) an operator wearing a wrist strap connected to a common ground point with the controlled worksurface, and (3) a static controlled protective bag. This combination of controls is considered a basic electrostatic protected area, or EPA. Assuming that all assembly, testing, or repair events are conducted at this EPA, the product will be protected within the EPA.

Expanding Basic ESD Controls To Meet Specific Process and Productivity Needs: Another Example

Most process environments are more complex than a single workstation and may require additional controls beyond the basics. For example, if many controlled workstations are necessary to perform the entire manufacturing or product assembly, each workstation must be an EPA. If the floor is not static controlled, the devices must be transported between controlled workstations (EPAs) in a closed ESD protective bag, package, or tote box. This is necessary because the person transporting the products from one EPA to the next is generating a charge while walking across an uncontrolled floor.

In large, active facilities it may be far more efficient to install an ESD floor and provide ESD control footwear to all manufacturing employees. In this way the employee is either grounded as though wearing a wrist strap, or cannot generate a harmful charge during the transport process, or both. This eliminates the need for enclosing sensitive devices in protective containers and allows greater employee mobility.

To assess the benefit of expanded ESD controls, ask questions pertinent to your situation, such as:

1. Will an ESD-controlled floor and footwear combination increase employee productivity while reducing potential damage during in-plant transport? If greater mobility and less internal packaging enhance process profitability, using these controls makes a great deal of sense.

2. Will an ESD-controlled floor and footwear combination provide added protection for high value, critical products? If redundant controls minimize or eliminate damage, reduce related warranty and customer service costs on high value products, using these controls may be of significant value.

3. Will an ESD-controlled floor and footwear combination provide sufficient “passive” control such that our devices are protected regardless of the employee’s action during transport? If the work force has high turnover or includes a large percentage of temporary workers, redundant passive controls can offset the lack of experience.

4. Will an ESD-controlled floor and footwear combination provide obvious ESD awareness sufficient to remind employees and customers of management’s commitment to ESD control? If the facility services many major customers that have ESD control guidelines governing the manufacture of their products, obvious ESD controls are a desirable sales and service feature. The required use of controlled footwear in a sensitive environment is a constant reminder to all employees that ESD protection is essential.

Similar consideration would apply to other key ESD control elements, including:

1. Floors

2. Worksurfaces

3. Equipment (Chairs, Carts, and Production Equipment)

4. Personnel Grounding

5. Clothing

6. Raw Materials

7. Production Aids (Tapes, Solvents, tools, fixtures, etc.)

8. Packaging

9. Grounding

But what should we buy?

Certainly, there are other ESD tools available such as auditing instruments, ionization, monitoring systems, and training. However, all of these ESD control products should be viewed simply as “tools,” much like those in a carpenter’s tool chest. Some tools are required, some are used only under occasional, specific circumstances, and others are “nice to have” when you need them. Clearly, it is best to use the proper tool for a given job to provide the desired results, and do so under the most advantageous financial conditions.

Once we determine that an ESD tool is necessary to solve a specific problem, the next question is what should we buy? To answer this question, the application and its parameters need to be defined, and the required attributes established. Among the concerns to be considered are:

 1. Application Description: Where is the product being used, why, and how? What’s good about the present product, what’s unacceptable? A product used in a hot, humid environment may have different desired attributes than one being used in a cold, dry area. What is the desired life of the product, or is it disposable?

2. Mechanical Requirements: What’s physically necessary to do the job properly? With floors, we consider type and density of traffic and possibly appearance; for packaging, we consider size, strength, and shock. When assessing worksurfaces, we would select hard, smooth surfaces for assembling system chassis, and soft, cushioning materials for small mechanically sensitive items.