Frequently Asked Questions

• Reaction with the contaminant and cleaning ability
• Environmental Impact
• User health and safety issues (risk of fire, explosion, cancer, fetal disorders, etc.)
• Operational cost
• Presence of odors
• Cleaning cycle time
• Ability to clean different solder pastes (flexibility)
• Maintenance requirements
• Special storage and transportation requirements
• Waste management
• Machine design and specifications
• Ability to close-loop the process

• Initial capital cost
• The footprint
• Scrubbing action and the ability to deliver the chemistry into fine-pitch areas.
• User interface
• Potential to damage the stencil (high pressure sprays can bend delicate land mass area, heat, etc.)
• Ease of maintenance
• Ergonomics

Stencils that are cleaned for storage purposes should be allowed to dry naturally. Natural air-drying conserves energy and frees the machine for additional wash cycles. Automatic drying of every stencil on every cycle wastes time, energy and, if heated, will damage the stencil.

In cases where the stencil is required for production, the fastest and safest way to dry a stencil is with hand-held, low-pressure (15 psi) dry compressed air (the same air used to operate a pick and place machine). The principal is not to “blow” the water off of the stencil; it is to apply the dry air to the surface of the stencil. The dry air absorbs the moisture. It’s like seeing alcohol evaporate. You can dry a 29″ stencil in approximately 2 minutes. Or, the Model 6000 Stencil Cleaner is available with optional automatic drying using low-pressure and low temperature dry air, which takes 6-8 minutes to dry a stencil.

Heat will damage the stencil and high-pressure air will bend delicate land mass areas between fine-pitch apertures. High-pressure nozzles are also a hazard. If loose, they can become projectiles and cause injury. High-pressure air (air knives) can cause “fugitive” solder balls to become airborne.

All Smart Sonic Stencil Cleaners are designed to clean up to a 29-inch (750mm) stencil. Smart Sonic can customize a machine with minor modifications to service a larger stencil.

No! Studies have shown that there are four primary factors that can affect the adhesive bond of the screen to the frame and metal etched foil. Heat is the most common cause of adhesive breakdown. The adhesives used to construct the stencil are heat-cured at approximately 160 degrees F (70 C). If a stencil is washed in hot water or dried with hot air, the heat-cured adhesive can weaken and fail. Also, the metals used to construct the stencil (aluminum frame, stainless steel or polyester screen and stainless steel, brass or nickel metal etched foil) will expand and contract which stresses the adhesive bond.

The second factor is long exposure to moisture due to long cleaning cycles or “soaking” the stencil prior or after cleaning. Adhesives are hygroscopic (absorb moisture). Long cleaning cycles or soaking times will cause the adhesive to swell and weaken.

Third are cleaning chemicals containing miscible solvents (VOCs). These harsh solvents can be aggressive and attack the adhesive bond of the stencil.

Finally, High-pressure sprays and high-pressure air knives will bend the delicate landmass areas between fine-pitch apertures.

The Smart Sonic process cleans without heat, wash cycle times are less than 2 minutes, high-pressure sprays and air knives are not used and 440-R SMT Detergent is the only VOC-free stencil cleaning chemistry. Stencils are safely cleaned and fast.

Wet solder paste will clean in 1 – 2 minutes, depending on the flux type. Drying can be accomplished naturally, or expedited by using hand-held low-pressure dry compressed air (approximately 2 minutes). The total cycle time to wash, rinse and dry a stencil, when using hand-held dry air is approximately 3 – 4 minutes.

Because 440-R SMT Detergent does not react with the solder paste and is not consumed during the cleaning process, the amount of chemistry used to clean solder paste is very predictable.

When cleaning no-clean, RMA, and lead-free, the Models 1500 and 1550 will use approximately 2 gallons of 440-R SMT Detergent per month. The ErgoSonic and Model 6000 will use approximately 3 and 4 gallons per month respectively (based on changing the wash water every four weeks). The bath life can be extended up to 6 months with the optional Filter Recirculation System or the EnviroGuard system.

When cleaning post solder flux residue or SMD Adhesives, the amount of 440-R SMT Detergent used will depend on the amount of contaminant cleaned. If large post-solder flux contaminated items are cleaned, such as pallets and oven radiators, a filter recirculation system installed on the wash tank will remove excess flux and prolong the life of the chemistry.

No! Many stencil manufactures recommend the Smart Sonic Stencil Cleaning Process not only because it cleans better than other stencil cleaners, but also because it will not damage the stencil.

High temperatures and high pressures are what cause stencil damage. Hot wash water or hot drying air will breakdown the glue on a stencil and cause distortion due to expansion and contraction. High-pressure sprays and high-pressure air knives will bend the delicate land mass areas between fine-pitch apertures.

Another issue is long exposure to moisture due to long cleaning cycles or “soaking” the stencil prior or after cleaning. Adhesives are hygroscopic (absorb moisture). Long cleaning cycles or soaking times will cause the adhesive to swell and weaken.

Cleaning chemicals containing miscible solvents (VOCs) can be aggressive and attack the adhesive bond of the stencil.

The Smart Sonic process cleans without heat, wash cycle times are less than 2 minutes and 440-R SMT Detergent is the only VOC-free stencil cleaning chemistry. Stencils are safely cleaned and fast.

Other stencil cleaners require that the user buy the machine from one vendor, the chemistry from another and the waste management system from still another. No one vendor is expert on the complete process and the user is expected to take total responsibility. When the process fails, the different vendors blame each other and the user is stuck in the middle with little recourse.

Smart Sonic provides the complete process and guarantees the performance. The Smart Sonic Stencil Cleaning Process has been field-tested since 1990 by well over 1,000 users. The process works, it is safe and it is economical.

Smart Sonic is the most widely used stencil cleaning process in North America. Over 1,000 systems have been installed worldwide. Customers include: Intel, Motorola, Jabil, Sony, Flextronics, Temic, Nokia, and many more.

The Models 1500 and 1550 will use approximately 2 gallons (7.5 liters) of 440-R SMT Detergent per month. The Model 6000 will use about 4 gallons (19 liters) per month.

The energy required to operate the machines is very low because 440-R SMT Detergent cleans at low temperatures, the ultrasonic generator has a very low amp draw and the cleaning cycles are very short.

When using the EnviroGuard Closed-loop System, electrical consumption is negligible and filters are replaced when needed.

When using a wastewater evaporator to manage the wastewater, energy consumption is very low because wastewater is evaporated at a rate of 4 – 6 gallons per hour. Therefore, an evaporator servicing a Model 1500 or 1550 will only be operating approximately 10 – 12 hours per month (20 – 30 hours per month for a Model 6000).

The most important factor of any cleaning process is always the chemistry. Smart Sonic’s 440-R SMT Detergent is the “backbone” of the cleaning process. Without 440-R SMT Detergent, ultrasonic stencil cleaners will not clean as well.

Smart Sonic introduced the original ultrasonic stencil cleaning process in 1990. We have more experience in ultrasonic stencil cleaning than all other competitors combined.

Yes. Misprinted substrates clean in much the same manner as fine-pitch stencils. Solder paste from within vias will also clean well.

Populated misprinted PCBs should never be cleaned in a “spray” style stencil cleaner. The solder balls from side “B” will broadcast throughout the wash chamber and contaminate the components on side “A”.

A Smart Sonic Ultrasonic Stencil Cleaner does not spray or circulate the wash solution. The PCB can be oriented with the paste side down. When using an ultrasonic stencil cleaner, the solder paste from side “B” falls freely away from the board by gravity. Components on side “A” are less likely to become contaminated with solder balls when using ultrasonics.

When cleaning populated misprints, frequencies should be kept at 40 KHz or higher (the lower the frequency, the more aggressive the cleaning action) and ultrasonic power (power density) should be kept at a minimum. Because of the efficiency of 440-R SMT Detergent, Smart Sonic does not need to use high-powered ultrasonic energy. Research indicates that ultrasonic power should be kept lower than 10 watts per liter of wash solution. Because of the superior cleaning efficiency of 440-R SMT Detergent, Smart Sonic systems are able to clean effectively at less than 10 watts per liter of wash solution! Assuring the utmost safety for populated assemblies. [Total power of ultrasonic energy (watts) / Total capacity of wash tank solution (liters) = Total watts/liter]

When ultrasonics was first developed in the 1950s, the technology was very crude and uncontrollable and the PCBs were very cumbersome and delicate. The two technologies were not compatible. Delicate wire bonds would break because of the low (20-25 kHz) and constant frequencies that were used. The lower the frequency, the more aggressive the ultrasonic cleaning action.

Today’s ultrasonic systems are the most controllable precision cleaning technology available. The user can control virtually every parameter. In addition, today’s PCBs are very compact and durable. The two technologies are now very compatible. Many Smart Sonic customers clean double-sided misprints with their ultrasonic stencil cleaner.

When cleaning populated misprints, frequencies should be kept at 40 KHz or higher (the lower the frequency, the more aggressive the cleaning action) and ultrasonic power (power density) should be kept at a minimum. Because of the efficiency of 440-R SMT Detergent, Smart Sonic does not need to use high-powered ultrasonic energy. Research indicates that ultrasonic power should be approximately 10 watts per liter of wash solution. Smart Sonic systems are able to clean effectively at less than 10 watts per liter of wash solution, assuring the utmost safety for populated assemblies. [Total power of ultrasonic energy (watts) / Total capacity of wash tank solution (liters) = Total watts/liter]

No! With Smart Sonic’s 440-R SMT Detergent, you will be able to clean any type of solder paste in the same machine at the same time.

Other stencil cleaners use chemistries that only selectively clean a few types of solder paste. They may clean RMA well but fail when attempting to clean no-clean or lead-free. (Alcohol is a good example of a selective or “vertical” type of chemistry).

It is estimated that up to 72% of all solder defects are a result of the screen printing operation. Thus, having a clean and accurate stencil is a major concern. An SMT stencil that has maintained good structural integrity and has zero contamination within the apertures will produce a better and more consistent print, which reduces incidence of misprints and downtime.

Yes and no. They are similar in that they all use ultrasonic cavitation as the mechanical scrubbing action. However, some require very high ultrasonic power because of the poor cleaning characteristics of the chemistry used. It has been demonstrated that high power ultrasonics can damage populated PCBs. The cleaning efficiency of 440-R SMT Detergent allows Smart Sonic to use the lowest effective ultrasonic power in the industry, assuring safety when cleaning populated misprints yet effectively cleaning stencils better than any other process. Without the proper chemistry, all ultrasonic stencil cleaners are similar. Some may have a few more “bells and whistles”, some may be better engineered ergonomically or for ease of use, but they all use ultrasonic cavitation as the mechanical scrubbing action.

Smart Sonic has been manufacturing ultrasonic stencil cleaners since 1990. We have made the mistake years ago that new competitors are just now experiencing. A 29″ stencil is only contaminated a maximum of 25-26 inches from one end. Therefore only 26 inches of the stencil requires immersion. The remaining 3 – 4 inches remains outside of the wash solution and serves as a convenient “handle.” Otherwise, the user would need to wear gloves or the stencil would need to be placed into a basket.

Systems that totally immerse a 29″ stencil need to be made taller to accommodate the additional 4 inches. This additional height makes it more difficult to load and unload. If the stencil is totally immersed, the user will need to load the stencil into a basket. Now, the user will need to lift the weight of the stencil and basket. The basket handles will be above the stencil which means the user will need to use a step ladder to clear the top of the machine.

OSHA frowns on an operator lifting anything above their shoulders. Therefore an automatic hoist may be required. If a step is used, OSHA may require a handicap ramp installation. A ramp will occupy 3 times the floor space as the cleaner.

By making the tank only as large as the required cleaning area, the system is more efficient, uses less wash solution, and therefore generates less wastewater.

This is just one of the many advantages that Smart Sonic has gained from years of experience.