WHAT CHALLENGES WILL WE SEE in critical cleaning over the next three to ten years? In an accompanying article1, Barbara obtained insightful responses from members of the cleaning and contamination control community. As independent critical cleaning consultants, we would like to highlight a few additionalchallenges.
One challenge is to control manufacturing variables throughout the supply chain. Critical cleaning is affected by an incomplete understanding of the initial stages of assembly. The solution starts with communication with the supplier and proceeds through documentation, refinement, and control. Even with stringent cleanliness specifications for final assembly, initial fabrication is often performed outsideof a cleanroom.
Supply chains can be complex. Frequently, an array of outside suppliers, such as machine shops and plating companies are employed. For decades, we have seen instances where companies performing final assembly have limited knowledge of specific cleaning processes employed by their suppliers. In some cases, outside suppliers outsource some of their fabrication to yet additional fabricators.
The final assembler is viewed as responsible for all of the fabrication processes. Therefore, one near-term cleaning challenge for final assemblers is to document sub-vendor processes. Sub-vendors must disclose specifics of materials and processes for manufacturing and cleaning. Manufacturing materials and processes can include metalworking fluids, blocking and deblocking agents, lapping and polishing compounds, and surface modification steps. Changes in manufacturing materials and processes can impact the final product. It is prudent for final assemblers to require approval before suppliers (or their suppliers) alter a fabrication process.
When is cleaning required? Sometimes, we find that a cleaning step can be eliminated because both the customer and the supplier assumed that the other was NOT performing the step and therefore added it to their process. Unfortunately, sometimes each assumes a step IS being performed by the other, in which case a critical cleaning process may be lacking.
Design for Assembly
Another challenge is to coordinate with customers,both internal and external, to design a product that can be assembled. It may be possible to suggestdesign changes that maintain performance, yet simplify assembly, cleaning, and contamination control. This could involve modifying component physical design,such as blind holes.
As parts get smaller, it becomes harder to find acceptable cleaning agents and processes that can penetrate into small spaces and then be adequately removed. Cleaning is a surface process. Ultimately, with nano-scale devices, the surface is the product.
Safety and regulatory issues
It is a challenge to be proactive rather than reactive to safety and environmental concerns. We operate in a world that is subject to ever increasing worker safety and environmental impact regulation. It is wise to incorporate safety/environmentalpersonnel into the design and cleaning process development team.
What are the consequences of neglecting this step? The response by regulators to an otherwise thoughtfully-developed process may be: “Oh, you can’tuse that!”
Matching the cleaning process to the soil
The challenge is to match the process to the soil.Both soils and cleaning processes change in response to safety/environment drivers, stringent cleanliness specifications, and economic pressure. A change in the metal-working fluid may require a cleaning process modification. When changes are not coordinated, the surface and product quality may be impacted. Coordinating changes can minimize theneed for capital investment and employee retraining.
Over the next decade, critical cleaning will pose greater technical challenges. To meet those challenges, communication, coordination, and process integrationare essential.
B. Kanegsberg, “The Future of Critical Cleaning,”Controlled EnvironmentsMagazine, October, 2006.
Barbara Kanegsberg and Ed Kanegsberg are independent consultants in critical and precision cleaning,surface preparation,and contamination control.They are the editors of “Handbook for Critical Cleaning,”CRC Press.Contact them at BFK Solutions LLC., 310-459-3614;firstname.lastname@example.org;www.bfksolutions.com.