Dangelmayer Associates provides an array of ESA ESD Cleanroom Controls Services:
Modern products are increasing in complexity and more are requiring cleanrooms for some part of their production. Static charge is a cleanroom contaminant that must be eliminated to enhance the production of semiconductors, disk drives, flat panel displays, medical and optical devices, and a variety of other products.
ESD damage issues in cleanrooms are similar to those in other electronics environments. However, the methods in common use to control static charge and eliminate ESD damage are not always compatible with cleanliness requirements. Many ESD control materials are not cleanroom compatible. Personnel ESD control procedures are more difficult to apply in cleanrooms due to the specialized garments required to be worn in cleanrooms. Finally, the processes and materials required to be used in cleanrooms are often static generating and unable to be modified.
Establishing an effective static control program in the cleanroom requires knowledge and attention to the cleanliness requirements and procedures of the cleanroom as well a thorough knowledge of ESD control methods. We can provide guidance in the choice of personnel grounding, static dissipative materials, and ionization for use in a static control program in a cleanroom.
Electrostatic Attraction (ESA) Control
Cleanliness and chemical process requirements in the cleanroom make extensive use of insulating materials such as glass, Teflon, Kynar and other plastics. Personnel are enclosed in cleanroom garments, booties, and gloves, also made of insulating materials. The products themselves make extensive use of specialized insulating materials. This variety of dissimilar materials, coupled with low humidity conditions in cleanrooms, assures that high levels of static charge will be generated.
The presence of static charge in the cleanroom, on products as well as other critical surfaces, increases the deposition of particles on these surfaces. Electrostatic forces of attraction are known to exceed other particle deposition mechanisms, such as gravity and diffusion. Eliminating ESA results in cleaner products and fewer particle related defects.
A thorough knowledge of particle generation and mitigation methods, coupled with an understanding of cleanroom requirements for static control, leads to effective solutions for ESA issues throughout the cleanroom facility.
We offer the only team of experts with both cleanroom and ESD diagnostic expertise. In fact, we have written the book on ESD programs for Class 0 devices in cleanrooms. We also have the world’s foremost ionization expert and can develop cleanroom construction specifications for today’s technology. Thus, we are uniquely qualified to resolve any ESD or contamination issue in cleanroom applications.
Overview: Provide technical advice and solutions to electrostatic contamination issues utilizing a three–pronged approach:
- Diagnose and Solve Cleanroom Contamination Issues
- Diagnose and Solve Static Control Issues
- Provide Education to personnel in contamination and static control principles to implement ongoing solutions, including the generation of corporate cleanroom requirements
This methodology is effective in preventing electrostatic contamination through all the stages of planning, design, construction, and operation of cleanrooms:
- Pre–Visit Discussions and Investigations
- Contact stakeholders to define requirements
- Review existing documentation
- Summarize current program and anticipated future needs
- On–site Visits
- As needed to review current practices, investigate problems, and propose solutions
- Detailed Findings Report provided
- Review of industry “best practices” and their applicability
- Change implementation planning comparing current methods with industry standards and recommendations for new methods, test limits, audit procedures, instrumentation, etc.
- Follow–up visit by D.A. personnel as needed
- Further evaluate the recommendations and their efficacy in resolving problems
- Ongoing review of all planning, construction, and operations documents
- Final report
- Based upon the findings from the visits, data collected and resulting defect reduction
- Final design and construction documentation
Pre–Visit Discussions and Investigations
- On–line teleconferences with company personnel to fully understand the manufacturing process in detail and describe the test methodologies in use
- Determine and agree upon an appropriate monitoring plan to measure defects on product and other surfaces
- Review of past/current data to understand trends/etc.
- Airborne particle count
- Foreign material defects
- Review of current cleanroom specifications and procedures
- Summarize future requirements
- Provide recommendations regarding 3rd Party cleanroom certification
On–site Visits – Example (tailored to specific customer needs)
- Typically a 3–day visit with at least two personnel from Dangelmayer Associates to evaluate the cleanroom and static control issues
- Day 1 – Cleanroom–focused evaluation
- Make airborne particle counts, focusing on locations near operating equipment
- Examine the surface cleanliness of the product as it moves between processes, identify particle sources
- Determine the effectiveness of any cleaning operations
- Evaluate cleanroom protocol, handling, cleaning, and personnel related issues
- Day 2 – Static–focused audit evaluating static generation and any existing means for mitigation
- Pay particular attention to residual charge from the manufacturing operations, cleaning operations, coloring operations, and unwind/rewind operations
- Evaluation of all static mitigation methods and corporate static control program
- Day 3 – Evaluation of any remaining issues
- Additional review of issues previously indentified
- Preliminary testing of any static or foreign material mitigation techniques
- Closing meeting to review findings
- Detailed report within 2–weeks of the first visit with preliminary recommendations
- Six – Eight week waiting period for implementation of preliminary recommendations
- Bi–weekly (or as needed) teleconferences to review progress
- Possible follow–up visit by D.A. personnel to further evaluate the recommendations and problem resolution
- Investigate further recommendations as needed
We offer customized personnel training programs as needed, including onsite classes and web–based training
- Preliminary design and construction documentation for review
- Ongoing support of the contamination and static control program development and implementation as needed
- Detailed final report issued based upon the findings from the visits, data collected and resulting defect reduction
- Detailed design and construction documentation for electrostatic and other contamination issues