1. Selecting a Stencil Cleaning Process
- Chemistry
- Cleaning Machine
- Waste Management
There are three major components of a stencil cleaning process. Many customers focus on the cleaning aspects of the chemistry and machine and fail to recognize the importance of the Waste Management system. If the waste management and environmental impact of a new process is not sound, the environmental regulators may disallow it’s use in the future.
2018/11/18
Smart Sonic

2. Goal and Objectives
Obtain an environmentally safe, user safe and flexible stencil cleaning process
Must be cost effective (start-up and operational)
Must clean fine-pitch
Must clean current and potential future solder pastes
Must meet current and future environmental regulations
Must not pose any user health or safety issues
Must not damage stencils
Possibly clean other applications (adhesives, flux residues)
“Does it clean?” is no longer the only question an assembler needs to ask. The stencil cleaning process has been identified as the most hazardous process with the highest potential environmental impact of any SMT assembly process. Because of this reputation, regulations can be expected to become more strict. Health hazards due to chemical vapors and safety hazards due to flammable chemicals and machines with non-protected pinch points are highly regulated in most areas. Environmental regulations have eliminated CFCs and are minimizing VOCs more each day. Drain disposal can be a liability for a company due to “Super Fund” clean-up laws.
High-pressure sprays and hot drying air used to clean rugged SMT assemblies will damage a fine-pitch stencil.
2018/11/18
Smart Sonic

3. Limiting Factors Heat Sensitivity Fine-pitch Applications
Stencils are heat sensitive. Hot water or hot drying air can breakdown the glue, bonding the screen to the frame and metal etched foil. Heat can also cause distortion of fine-pitch apertures due to expansion & contraction of metals
Fine-pitch Applications
Cleaning Applications
Solder paste, SMD adhesives, flux residue from pallets or radiators, etc.
Environmental Regulations
Will Flux Types or Pitch Size Change in Future?
Stencils use a heat-cured glue (approx. 160 F, 70 C) to bond the screen to the frame and metal etched foil. If the stencil is washed in hot water or dried with hot air, the glue can breakdown and fail. Even “frameless” stencils can be distorted by elevated temperatures. Stainless steel is known to have a very poor memory, once it expands, it fails to contract back to the exact position. As a result, fine-pitch apertures can become distorted when washing with hot wash solutions or drying with hot air.
Fine-pitch apertures are difficult for spray systems to penetrate. Solder contamination is often left in the apertures.
While the primary application is to clean stencils, a stencil cleaner using the right chemistry is often used for other cleaning applications.
Just because a process adequately cleans, does not mean it is correct. Environmental regulations change more often than the seasons. The only way to be sure that a process will be acceptable in the future is if the process is EPA Certified.
A process that cleans your current solder paste may not clean the new paste you wish to incorporate in the future. A good process will clean all types of solder paste and support and future changes.
2018/11/18
Smart Sonic

4. Where To Start Select the Chemistry first!
The most important factor of any cleaning process is always the Chemistry
The chemistry determines the:
Reaction with the contaminant
Environmental impact
User safety – health, fire, explosion potential
Operational cost of the process
Presents of odors & vapors (hot water vapor contamination)
Cleaning cycle time
Process flexibility to clean different solder pastes
Requirement for heat (stencil damage, energy use)
Maintenance requirements
Storage and transportation requirements
Waste management
Many users make the mistake of shopping for a cleaning machine first (probably because it is the largest capital item). Unlike shopping for a printer or pick and place where the machine is the most important factor, the chemistry is always the most important factor of any cleaning process.
For example: Greasy hands from working on an automobile engine can be vigorously scrubbed under hot water all day and fail to become clean. However, use of the right chemistry and the hands clean easily. This is true of spray machines, ultrasonic machines or manual cleaning.
2018/11/18
Smart Sonic

5. Where To Start The Cleaning Machine only determines the:
Initial capital cost
Footprint
Mechanical scrubbing action and it’s ability to deliver chemistry inside fine-pitch apertures
User interface and process simplicity
Potential to damage stencil (high pressure sprays, heat, etc
Ease of maintenance
After the proper chemistry is identified, how the chemistry is applied depends on the geometry of the part to be cleaned, the production throughput, and characteristics of the chemistry (solvent, aqueous, etc.).
2018/11/18
Smart Sonic

6. Where To Start Waste Management determines the: Permit requirements
Long term liability
Documentation requirements (manifestation)
Quantity solids vs. liquids
Cost of disposal
Processes using solvents and aqueous chemistries containing hazardous ingredients such as ethyl ethers, VOCs, etc. my be difficult to obtain permits.
Volumes of liquid waste can be very expensive to handle. Solids are usually easier and less costly.
Capital and operational cost of equipment vs. hauling fees and liability can often justify the purchase of a waste management system.
2018/11/18
Smart Sonic

7. Today’s Choices CHEMISTRY CLEANING MACHINE WASTE MANAGEMENT Solvents
Semi-aqueous
Aqueous (plain water, saponifiers, detergents)
CLEANING MACHINE
Hand clean
Spray in air
Spray under immersion
Ultrasonics
WASTE MANAGEMENT
Haul away
Filter
Evaporate
2018/11/18
Smart Sonic

8. Today’s Choice of Chemistries
Solvents
Advantages
Clean without heat
Usually dry fast
Some are cheap (alcohol, acetone, etc.)
Disadvantages
Environmentally problematic
Pose health and safety hazards (cancer, fetus, fire, explosion)
Do not clean all types of solder paste
Long term disposal liability
Odors in workspace
Special storage & transportation
Special permit requirements
Some are costly
From an environmental and health perspective, solvents are usually not a long term solution. Environmental regulators are forever targeting solvent operations.
Solvent vapors are associated with cancer and fetal disorders. Flammable solvents are not acceptable because of the fire and explosion dangers. Stencil cleaners using flammable solvents are known to explode. Ignition sparks origination range from static discharge to mechanical sparks resulting from metal spray nozzles hitting the metal stencil.
2018/11/18
Smart Sonic

9. Today’s Choice of Chemistries
Semi-aqueous
Advantages
Can be closed-looped
Clean without heat
Disadvantages
Environmentally problematic
Requires water rinse (two waste streams)
Requires special equipment
Usually expensive
Do not clean all types of solder paste
Requires special permits
Odors in workspace
Requires dry cycle
Semi-aqueous is the same as solvent systems except water is required for rinsing. Semi-aqueous systems pose the same problems as solvent systems with the addition of an aqueous waste stream to contend with from the rinse cycle.
2018/11/18
Smart Sonic

10. Today’s Choice of Chemistries
Aqueous - plain water
Advantages
Cheap
One waste stream
Can use spray or ultrasonic equipment
Waste water can be evaporated
Disadvantages
Cleans only water soluble solder paste
Requires dry cycle
Not flexible
May require heat
Many water washable solder pastes can be successfully cleaned in plain water without added chemicals. However, future decisions may incorporate different solder pastes (lead free, no-clean, etc.) that may require a cleaning chemistry. Buying a system to clean only water washable solder paste may tie the user’s hands in the future.
2018/11/18
Smart Sonic

11. Today’s Choice of Chemistries
Aqueous – Saponifiers
Advantages
Same chemistry used to clean PCBs
Disadvantages
Caustic
Require heat that will damage stencils
Contain hazardous ingredients that prohibit evaporation of wastewater
Consumed during cleaning process
High cost of operation
Hot water vapor can contaminate assembly area
Pose safety hazard to user
High pH will (13+) will oxidize aluminum frame
Odor in workspace
Saponifiers are different from detergents. A saponifier is an alkaline substance that when combined with a fatty oil (rosin) forms a water soluble soap. The resulting soap can then be rinsed off with plain water. Therefore, saponifiers clean by chemical reaction and require constant replenishment. The chemical reaction requires heat (hot water).
Detergents are surfactants (wetting agents). Detergents can be formulated to clean at low temperatures and are not consumed during the cleaning process. Therefore, detergents will perform much longer than saponifiers.
2018/11/18
Smart Sonic

12. Today’s Choice of Chemistries
Aqueous – Detergents
Advantages
Flexible - Clean many types of solder pastes
Can clean without heat
Can be environmentally safe
Can be user safe
Surfactant (wetting agent) is not consumed in cleaning process
Inexpensive
Wastewater qualifies for evaporation or filtration
Some can also clean adhesives and flux residues
Field tested effective for over 10 years
Disadvantages
Requires dry cycle
Detergents can be formulated to perform specific cleaning objectives. Smart Sonic’s 440-R SMT Detergent has been formulated to clean all types of solder paste without the use of hot water R SMT Detergent also performs extremely well for cleaning SMD and conductive adhesives and flux residues from tooling. However, these applications require warm water (95oF, 35oC).
2018/11/18
Smart Sonic

13. Today’s Choice of Machines
Spray in Air & Spray Under Immersion Systems
Advantages
Able to use aqueous, semi-aqueous or solvent chemistry with certain modifications
Usually simple operation
Disadvantages
Cannot spray into fine-pitch apertures effectively
High pressure sprays can bend delicate land mass areas
Cannot clean vias of misprinted PCBs
Cannot clean double sided misprinted PCBs because of solder ball contamination of side A
Requires clumsy fixturing of stencil
Requires internal filtration system
Will only clean as well as the chemistry used in it
Photos from the Smart Sonic brochure, which were published in the July, 1996 issue of EP&P Magazine, show that sprays cannot penetrate fine-pitch apertures. That same article indicates that high pressure sprays can bend the delicate land mass areas found between fine-pitch apertures.
Again, from that same article, it is pointed-out that spray systems should not be used to clean double-sided misprinted boards because the broadcasted solder balls from side B will contaminate the components on side A.
Because the solder balls are not spray broadcasted, an ultrasonic system is recommended. The solder balls fall freely away from the populated side simply by gravity.
2018/11/18
Smart Sonic

14. Today’s Choice of Machines
Ultrasonics
Advantages
Microscopically cleans fine-pitch apertures
Will not cause bends in delicate land mass areas
Simple operation
Filtration system usually not required
Cycle time can be fast with right chemistry
Low maintenance
Inexpensive manual machines clean just as well as more expensive automated systems
Disadvantages
Will only clean as well as the chemistry used in it
Smart Sonic uses ultrasonics to deliver our 440-R SMT Detergent into fine-pitch and ultra fine-pitch apertures. Without the 440-R SMT Detergent, the ultrasonics will do little.
2018/11/18
Smart Sonic

15. Waste Management Systems
Haul Away by Others
Advantages
Easy
Disadvantages
Long term liability put on user (User responsible for mishandling and/or accidents of waste hauler-Super Fund)
High and continued cost
Hazardous waste haulers are a liability to any company. Long term liability for hazardous waste disposal cannot be transferred. If the waste hauler does not properly dispose of the material or has an accident, the liability for cleanup is always with the generator.
Manifestation documents are costly and time consuming to complete.
2018/11/18
Smart Sonic

16. Waste Management Systems
Filtration
Advantages
Inexpensive micron filtration for water washable solder paste
Easy maintenance
Disadvantages
Expensive ion exchange or reverse osmosis systems required for no-clean, RMA and synthetic solder pastes
Always an effluent left for drain disposal which exposes user to potential liabilities of drain contamination (Super fund laws)
Continued cost of replacement filters
Not 100% effective
When using filtration, there is always an effluent left for disposal. Even drain disposal can cause a big problem. U.S. EPA regulations state that if there is a hazardous contamination (lead) within the drain system and the source cannot be identified, everyone discharging waste that has been expose to lead, within a 50 mile radius, will share in the cleanup cost. So, even if your filtration system is 100% safe, you may end up paying for a problem that your neighbor created.
2018/11/18
Smart Sonic

17. Waste Management Systems
Evaporation
Advantages
Inexpensive – Capital cost is usually less than ion exchange or reverse osmosis filtration systems
Low operating cost – No replacement filters. Low energy consumption
100% effective
No liquid hazardous waste for disposal
Nothing goes to drain
Disadvantages
Maintenance is difficult for some models. However, maintenance cycles are usually infrequent
Requires ventilation or outdoor placement
When evaporating Smart Sonic wastewater, the non-hazardous water vapor goes to atmosphere reducing the waste to a small amount of solids for disposal. The solder paste is all recyclable via a dross process or can be melted in a wave solder pot. When using an evaporator, there is absolutely no liquid hazardous waste for disposal at all!
2018/11/18
Smart Sonic

18. Best Total Process Aqueous Detergent Chemistry
Ultrasonic Cleaning Machine
Evaporation Waste Management
Smart Sonic combines the best chemistry with the right cleaning machine and correct waste management. A total process from one source that is performance guaranteed and certified environmental and user safe.
When buying components from different vendors, the user takes full responsibility for the performance of the resulting process. If the process fails, the machine vendor will blame the chemistry and visa versa.
2018/11/18
Smart Sonic

19. The Smart Sonic Stencil Cleaning Process
440-R SMT Detergent
The only chemistry Certified Environmentally Safe and User Safe by the Environmental Protection Agency
Guaranteed to cleans all types of solder paste
Cleans at ambient temperature. No heat to damage stencils and no waste of energy to heat wash solutions
Not consumed during the cleaning process. A fixed amount is used between maintenance cycles. 5 Gallons (20 liters - less than $90) per month for Model 1500 and 2000 Stencil Cleaners
No special storage or transport requirements
Cleans SMD adhesives and post solder flux residues
Field tested for over 10 years by over 700 installations
SMT Vision Award Winner
Mild pleasant odor
Cost effective
2018/11/18
Smart Sonic

20. Smart Sonic Stencil Cleaning Process
Ultrasonic Cleaning Machines
Model 1500 – Semiautomatic
Lowest priced ultrasonic stencil cleaner
Cleans 29” (750mm) stencils in less than 2 minutes
Can clean solder paste, adhesives and/or flux residues
Small footprint, ergonomically designed for easy loading
Models 2000 and Semiautomatic
Similar to the Model 1500 with a few more bells and whistles
The Model 2003 has one heated wash tank and one ambient
Model 5000 Fully Automatic System
Wash, rinse and optional dry at the touch of one button
Cleans 29” stencils in less than 2 minutes (excludes drying)
Fully programmable
Easy to load and unload
2018/11/18
Smart Sonic

21. Smart Sonic Stencil Cleaning Process
Waste Management System - Evaporators
While the smart sonic waste water may be filtered like other
aqueous wastewaters, the Smart Sonic wastewater qualifies for
routine liquid evaporation. Most users see significant
advantages to evaporation over filtration.
Model SE-1 – Standard Evaporator with standard cleanout and maintenance features commonly used throughout industry
Model EZ-0 – Easy maintenance and easy cleanout makes this a popular system. Smart Sonic designed this system for unique compatibility with the Smart Sonic Stencil Cleaners
Either evaporator can be used with any Smart Sonic Stencil
Cleaner
2018/11/18
Smart Sonic

22. How Did We Get Here?
Smart Sonic introduced the industry’s first Ultrasonic Stencil Cleaner in 1990 to take advantage of our unique 440-R SMT Detergent. Since 1990, the Smart Sonic Stencil Cleaning Process has:
Satisfied the stencil cleaning requirements of over 700 SMT assemblers worldwide.
Been Certified Environmentally Safe and User Safe by the Environmental Protection Agency (EPA).
Been evaluated by industry experts and awarded top honors by the SMT Vision Award (twice), the NEPCON West Kiver Award, the Canadian High Technology Award, Certified by the California EPA and Verified Environmentally Safe and Effective by the U.S. EPA.
Smart Sonic has more experience with Ultrasonic Stencil Cleaning than all other manufacturers combined!
2018/11/18
Smart Sonic

23. Other Cleaning Applications
The Smart Sonic Stencil Cleaning Process will also perform exceptionally well in the following cleaning applications:
Clean solder paste from misprinted PCBs and tooling
Clean SMD adhesives and conductive adhesives from stencils, misprinted PCBs and tooling
Clean post solder flux residue from pallets, wave solder fingers, oven radiators, heat exchangers, air amplifiers, and tooling
2018/11/18
Smart Sonic

24. Summary The Smart Sonic Stencil Cleaning Process
Guaranteed to clean any type of solder paste from any fine-pitch stencil
Certified environmentally safe, user safe and effective by the Environmental Protection Agency
Cleans without heat
Long chemistry life – Low operating cost
No liquid hazardous waste disposal
Complete turn-key process from one source
Award winning and evaluated by industry experts
Over 1,000 satisfied customers worldwide
If you haven’t noticed, other systems are trying to copy Smart Sonic. However, they do not have our 440-R SMT Detergent, EPA Certifications, satisfied customers or years of experience. At Smart Sonic, stencil cleaning is our only business – not just a sideline!
2018/11/18
Smart Sonic