Using ACL 7600 IPA Wipes in Conjunction with ACL 8690 Acrylic Conformal Coating for PCB Rework/Repair Prep – Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide

In Steve’s latest Guest Blog for the Q Source Resource, he recommends a process of PCB preparation for rework/repair.

Preparing PCBs (printed circuit boards) for rework or repair is a very important process. ACL Staticide has developed and manufactures an array of precision cleaners and surface preparation products, along with final finishing conformal coats to aid in this application. These products’ primary focus is in the area of printed circuit board repair and OEM manufacture. Let’s cover some key areas of PCB rework and repair using a two-step process for surface preparation and finishing.
In many instances of PCB repair, surface preparation with a pre-saturated wiper followed by treatment with conformal coating is the process of choice for reworking a board and getting it back into service.

With that in mind, ACL’s 7600 IPA Wipers are perfect for surface preparation following repair. The 7600 is a pre-saturated wipe using a precise 70/30 blend of extremely pure, electronics-grade isopropyl alcohol blended with deionized water to prevent premature evaporation of the cleaning solvent. The solvent is added to the wiper in a cleanroom environment. These wipers use a non-woven Sontara® technology designed to be extremely low linting, even at the perforation. Available in a 100-wipes reclosable container (made of non-hazardous material), the 7600 product is perfect for final finishing work of any circuit board. It is great for removal of hand oils, conductive greases, carbonized soils, dust/dirt, light flux residues, and a variety of other soils.

A 2-wiper use process is recommended for general-purposed cleaning and hand wiping of larger components and various board surfaces. One wipe is used for initial cleaning of heavier residues, and a second wipe for final surface cleaning and finishing. All surfaces should be allowed to gently dry for one to two minutes, or dry using compressed air or a duster product like the ACL 8640 Turbo Blast Duster.

Following this process, the board is prepared and ready for application of surface protection like acrylic conformal coating. ACL’s 8690 Acrylic Conformal Coating is the product of choice for protecting the PCB and all surface components from oils, moisture, and most soils. It is used following surface cleaning and preparation with the 7600 IPA wipers. ACL 8690 can be applied to the entire board surface. It is dry to the touch in less than 30 minutes and completely cures in 24 hours. It provides protection as well as heat resistance and contains a UV dye indicator so that the user can be sure the entire board and all components have been treated. ACL 8690 leaves behind a high-gloss cure (making it suitable for final presentation to the customer at contract manufacturers) and prepares the board for final installation.

This process of using both the 7600 wipes and 8690 conformal coating in conjunction with each other for final board preparation and final surface finishing prior to installation helps eliminate potential failures and damage to PCBS or devices. Please contact us with related questions or comments.

Thank you, Steve! That sounds like the way to go when preparing printed circuit boards. We look forward to your future articles.

For information about , or to order, any of the ACL products mentioned in this blog, please visit QSource.com. You may also contact us via email or phone at 800-966-6020 and we will be happy to assist you.

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Flux Cleaning Myths: The Basics - Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide
 
In Steve’s latest Guest Blog he focuses on a few myths about flux cleaning

There are many myths and misunderstandings about cleaning solder flux from printed circuit boards. Let’s address some of those primary PCB cleaning & preparation myths and concerns for a variety of rework and repair operations.

To begin, we clean and remove most flux residues to prevent metal oxidation and generally poor electronic circuit connections.

Technologists and technicians alike are often advised to clean boards post-soldering processes with isopropyl alcohol (i.e., IPA). But there are proven chemical reasons for not using a hygroscopic solvent like IPA (hygroscopic solvents draw moisture from the air to themselves as an equilibrium mechanism) for basic board cleaning and further process preparation.

In most instances, IPA is too aggressive for most plastics and can intrude into parts and spaces creating undesirable effects. IPA is known to dissolve polystyrene and other types of plastic capacitors. By dissolving various materials, a potential low-ohm and conductive film is spread over the surface of the PCB while the flux itself (typically a very high solids material) is left untouched in a host of board surface areas, and in particular, at the solder joints. Leftover flux materials can be detrimentally conductive in many instances.

A LOOK AT FLUX MATERIALS

Rosin-based flux is generally not conductive unless it is baked on at extremely high temperatures (caramel or black in color). Generally, no-clean flux is just that. It does not always require cleaning and you may leave it on. Many low-solids flux materials, when applied under a correctly controlled process, will completely evaporate with time. Most water-soluble fluxes need to be removed simply because they leave behind a soap-scum-like residue, which is generally conductive.

Additionally, there are some very aggressive fluxes like RA that must be removed as they contain very acidic substances. RMA is the most prevalent rosin flux (RMA rosin = mildly activated and RA rosin = less activated). It is actually not the rosin that performs the flux activity, but another substance in the flux compound, which promotes spreading and adhesion. The basic rosin material is simply a carrying vessel for the active flux ingredient.

FLUX WORKS ON TWO FRONTS

When activated (and temperature controls this; most fluxes kick in around 100° C or 212° F), flux is a very reactive element that wants to bind with oxygen molecules. It is so reactive it can strip oxygen molecules that have already bonded with copper. So, it converts copper oxide back into basic copper. The second thing flux does is lower the surface tension of the solder. This lets the solder flow over the soldered surface, spread, and adhere.

Under a correctly controlled process, the flux is given some time to activate and do its work before solder is applied. Wave solder machines apply warm flux to the board first, then let it soak for a few seconds as the conveyor moves over a warming plate, and finally the flux is fully activated. The board then passes through the solder wave where the flux totally evaporates and essential leaves behind a clean board.

Solder paste works in a similar way. When conducting reflow processes, you have a ramp up to flux activation, a hold phase to let the flux do its work and evaporate, and finally, a ramp up to liquid phase where the solder melts and flows on the remaining flux. In theory, if reflow operations are done correctly, there should be minimal flux residue and board washing is simple or may not be required at all.

Boards that have been reworked (e.g., manually touching one individual component) will have residue and require washing with flux removers. The flux in solder wire is a different composition than the flux found in pens or liquid form. The flux in solder wire is dry powder and is more aggressive than paste as it has a shorter time to do its work.

Plus, there are specially formulated fluxes like the gel fluxes or tacky fluxes. These are formulated for the rework process, and the practice is to use a lot of it; so much of it that there is excessive residue and you need to remove it. The same goes for pen fluxes, which are also for rework. Most fluxes for wave soldering come in a 55-gallon drum, which is not something most end-users keep on the workbench!

In general, when performing handwork, you will need to clean the board unless no-clean is used, when doing reflow or wave soldering. If aesthetics are key, it’s important to clean. And, every kind of flux has its own specific flux remover. Some flux removers are broad spectrum. Most flux removers require flood cleaning; you need to use a substantial amount to effectively clean and wash a board. Simply squirting a tiny bit on does not work. It just leaves goop all over the board like a sticky film. You need to flood it on, let it soak for a few seconds, and in many cases, scrub with a brush. Then repeat the spray process to wash the “spent” material off the board. As a final process, let the board drip out and spray once more. If needed, apply warm air to dry. Never blow air using your mouth (human breath actually contains saliva, which is acidic). As the flux evaporates, it cools down the board which pulls moisture out of the air. Always use your reflow hot air gun for any type of final finishing and drying.

When it comes to technical cleaning, ACL Staticide manufactures top-quality rework and repair cleaning products and compliments, and QSource.com is your resource for all of them.

Thank you Steve, for that informative Guest Blog and for clearing up those flux cleaning myths. We look forward to your next blog submission.

For information about ACL Staticide and their related products, please visit our ACL Staticide Department at QSource.com. You may also contact us via email or phone at 800-966-6020 and one of our associates will be happy to assist you.

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Understanding Contact Cleaners with ACL Staticide: “On the Bench” Video

Steve Allen, VP of Marketing & Innovation for ACL Staticide (and regular Q Source Resource Guest Blogger), recently spoke to Q Source about Contact Cleaners for our “On the Bench” video series. Steve demonstrated how to clean a PCB using a variety of ACL’s Contact Cleaners to remove hand oils, thermal conductive greases, silicones, and more.

To purchase ACL Staticide Contact Cleaners, please visit QSource.com or contact us via phone (800-966-6020) or email.

Don't forget to look out for new "On the Bench" videos at QSource.com and on our YouTube channel.

An Update on the HCFC-225 (AK-225) Phase Out & Ban – Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide

Steve Allen's latest Guest Blog looks at the chemical replacements for AK-225 as it is approaches its total ban.

The EPA ban and elimination of HCFC-225 (also known as AK-225, and referred to that way from this point on) is a current topic of continuing concern in the area of electronics cleaning and printed circuit board (PCB) rework and repair. The banning of AK-225, effective January 1, 2015, will limit the number of available types of solvents for electronics cleaning. This will, once again, change the solvent cleaning landscape in our industry. It's important to understand what replacement chemistries will be available in 2015 and how this will affect end-users.

AK-225 falls under the EPA's Clean Air Act as a Class II ozone-depleting entity and is now defined as an Agency-Controlled Substance. It is thus deemed unlawful for any person to engage in interstate commerce of the solvent or any use of the substance unless it has been used, recovered, or recycled or used to produce another chemical, or finally, used as a refrigerant (until 1/1/2020). End-users may use, and continue to purchase, aerosols containing AK-225 made before January 1, 2015. Beginning January 1, 2015, AK-225 can only be used in the manufacture of end-user cleaning products if it has been used, recovered, and recycled, as per the Clean Air Act.

AK-225 (HCFC-225) is a cleaning solvent mixture of two isomers, HCFC-225ca and HCFC-225cb. AK-225 has many unique properties, including its ability to form azeotropes, strong solvency, and thermal stability, which makes it good for use in vapor degreasing. AK-225 is non-flammable, has a low acute toxicity, low viscosity, high density, and low surface tension. This list of great performance characteristics is what makes AK-225 such a great general-purpose precision-cleaning solvent. It is also why this particular solvent has been so difficult to replace with alternatives.

The Agency has approved more than 300 substitutes for multiple applications. Potential substitutes for AK-225 include DuPont Vertrel Solvents (Vertrel XF), n-Propyl Bromide (nPB), Trichloroethylene (TCE; mostly Chinese sources today), 3M hydrofluoroethers (HFEs), and Honeywell's Solstice Performance Fluid (Solstice PF).

DuPont's Vertrel has characteristics similar to AK-225, but is much more environmentally friendly. Solvents containing nPB work well for difficult precision-cleaning applications, but they are not considered environmentally friendly. From a health and environmental perspective, both nPB and TCE are not good replacements for AK-225 due to their low exposure limits and suspect carcinogenicity. The EPA is also currently evaluating the flammability limits of nPB. Additionally, TCE is an overly aggressive solvent making it unsuitable for use with most plastics and elastomers.

From an environmental standpoint 3M HFEs are great as they have been granted VOC exemption. Honeywell's HFO-1233zd(E) has a low global warming potential and is non-flammable. However, cost to the end-user for familiar cleaning applications may be an issue.

Because AK-225 is commonly used in high-end, Class 3 applications (like aerospace, medical, and biotech), qualification of replacement solvents is a difficult and complex process. It is not too early to start the process, and there are many choices to meet most every requirement. ACL Staticide has encouraged its end-use customers to initiate the replacement qualification process early to ensure solvent compatibility, performance, and product availability.

Considering all the facts and chemical replacement requirements from the EPA, ACL has developed a line of solvent chemistries and formulations designed specifically as AK-225 replacements. Our new line includes both flammable products and non-flammable products with our non-flammable alternatives developed specifically for AK-225. In particular, our new ACL 8624 A4 All Purpose Flux Remover & Cleaner has been formulated as a universal performance replacement for all former AK-225 applications. It has many of the same great features of AK-225, but without the ozone-depletion potential. It is recommended that the product be tested on plastics prior to use to determine plastic compatibility with each customer's unique application and process. Contact Q Source, Inc., your ACL Staticide distributor, at 800-966-6020 for more information regarding ACL's AK-225 replacements.

A big thank you to Steve, for another informative Guest Blog. We've appreciated your Q Source Resource contributions throughout this year and we look forward to more in 2015.

For information about ACL Staticide, or to purchase their related products, please visit our ACL Staticide Department at QSource.com. You may also contact us via email or phone (800-966-6020) and one of our associates will be happy to assist you.


For additional Q Source product information, reviews, how-to articles, and special offers please subscribe to our email newsletter.

More About the Basics of Flux in Electronics Soldering – Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide

Steve Allen, from ACL, is back with a further discussion of the basics of flux in electronics soldering

For those of us associated with the electronics manufacturing industry, we are well aware that solder flux is a very important part of the soldering process. Flux is necessary to reduce the oxides that tend to form whenever you have hot metals in contact with the air. In electronics, we use a rosin-core solder, a mild no-clean solder, a more aggressive lead-free solder, or a water-soluble solder to aid the soldering process and eliminate metal oxides. We take great care regarding flux to make sure that we have selected a product that's not plumbing flux or acid-core flux because we know that will tend to corrode parts and components over time; they're okay for pipes but not for electronics.

In many cases, we're looking at rosin solder flux (in paste form) for most applications. If the temperature's a little bit colder, it will tend to crystallize and solidify. But it can be melted with a little bit of heat from the soldering iron. Of course, when you heat flux it tends to produce smoke, so it's good to have ventilation or a fume extractor to be sure that you're not breathing in the caustic vapors created from heating the flux. When you heat a work piece, flux reacts with the metal oxides that are forming with the temperature and exposure to the air. These residual metal oxides tend to interfere with the metal-forming process of soldering. Flux will chemically react with these oxides to make a nice, clean metal from the solder forming process that will form a pristine alloy on the board.

As we know, many solders come with flux in the core. The solder is actually hollow and inside the solder wire there is a central core of flux. As you feed the solder into your work piece, the flux then distributes itself over the surface of the work, reducing the formation of metal oxides and preventing them from occurring during soldering. Flux core solder can be helpful in many soldering instances for small, specific solder and repair projects. Additionally, we should talk about water-soluble flux, which is a recent and significant improvement in flux. With water-soluble flux, cleaning becomes easier. With rosin-core flux, the flux is not water-soluble. It takes an aggressive solvent cleaner to dissolve it and to remove it from the work piece. While easier to clean, water-soluble flux may not be appropriate in all circumstances. It can leave a residual layer that may interfere with high-impedance and high-resistance circuits where you have resistances (10 mega-ohms or greater). The water-based flux may actually lower that resistance and cause the circuit to malfunction.

Solder flux is an essential element when soldering, as it makes the soldering project much easier and of higher quality. Unfortunately, leaving even the no-clean fluxes behind on a PCB can cause some serious issues in circuit performance and even disable components. As part of the basics of flux, it's important that we understand what leaving flux on a PCB can do to your circuit.

Leaving fluxes behind can seriously damage a PCB.

In many instances, no-clean flux may not need to be cleaned from a circuit to prevent the flux from physically destroying the circuit. Unfortunately, the presence of flux changes the capacitance between traces, conductive pins, and circuits, and can ultimately get into the mechanical workings of electromechanical components and bind them up. Flux that requires cleaning is very acidic and can eat away at traces and pins, changing their resistance and even destroying surface mount components if the flux is left in place too long.

One particular location in board rework and repair, where the direct presence of residual flux has a significant impact, is on or near the input circuits to a differential input. Differential inputs are often balanced and used for very precise measurements. The presence of flux here will not only throw off any measurement, but can cause the readings to drift significantly over time.

Electromechanical components are also significantly impacted by flux. Often these components are soldered in by hand in the first few prototypes. The hand soldering of these components often works just fine, and the circuit moves on to an initial low-rate production run where problems start to occur in switches and other “mechanical-based” components. Often what happens is that the change in flux application techniques causes flux residue to build up inside the mechanical component and either prevents it from physically moving or makes the switch work intermittently. Troubleshooting these problems is extremely difficult and can lead to significant time loss during troubleshooting. This leads to quality problems we are trying to prevent.

Often when making prototypes components will be hand-soldered in place, circuits will be modified during testing, and parts will be replaced. Each of these operations requires the use of flux, which will need to be cleaned. ACL has developed a complete line of flux removers for all of these specific applications.

No Cleaning – If the circuit is slow, not susceptible to noise errors or increased DC offsets, then no cleaning could work just fine. However, for most circuits leaving the solder flux on the board will cause errors and make troubleshooting much more difficult.

Hand Cleaning – Better than no cleaning at all. Circuits see faster warmup periods and less current offset issues.

Soaking in an Aerosol Solvent Spray – Similar to hand cleaning, aerosol soak and rinse methods can be very helpful in cleaning out mechanical components where hand cleaning simply can't reach.

While it is tempting to save the 10 minutes or so and not perform a proper cleaning, for precision circuits, cleaning is an essential step in the testing and manufacturing process. Keeping a PCB board free of flux build up will save countless days in the testing and troubleshooting process and significantly reduce the stress of tracking down random errors and quality problems. Invest the money and time in an effective cleaner and cleaning process and spend more time building and designing great circuits (rather than countless hours troubleshooting problems).

Thanks Steve, for yet another Guest Blog full of must-have info that our Q Source Resource readers can apply to their own work environments.

For information about ACL Staticide and their related products, please visit our ACL Staticide Department at QSource.com.

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ACL Staticide Flux Removers: “On the Bench” Video

ACL Staticide's VP of Marketing & Innovation and Q Source Guest Blogger, Steve Allen, paid us a visit to provide an overview of ACL's new aerosol cleaning products. In this "On the Bench" video, Steve talks about flux removers.

Focusing on ACL's Flux Remover No Clean, Flux Remover Lead-Free, Flux Remover Rosin, and Flux Remover Heavy Duty, Steve tells us about the need for flux removers and then demonstrates ACL's recommended cleaning process.

To purchase ACL Staticide Flux Removers, please visit QSource.com or contact us via phone (800-966-6020) or email. Shop our complete line of ACL products at our ACL Staticide Department at QSource.com.

Don't forget to look out for new "On the Bench" videos at QSource.com and on our YouTube channel.

How to Use the 80:20 Rule to Focus on the Business Innovation Process - Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide
 
Our guest blogger, Steve Allen from ACL, looks at how to apply the Pareto Principle’s 80:20 rule in your business practices

"There is nothing quite so useless, as doing with great efficiency, something that should not be done at all."—Peter Drucker

Italian Economist Vilfredo Pareto

The Pareto Principle (also known as the 80:20 rule), irrespective of the nature of your business, holds that 80% of the consequences of any action come from 20% of the causes. This principle can actually be applied to everything you do. At ACL, we implement 80:20 simplification and rationalization disciplines into everything we do, including new product development and commercialization.

The original 80:20 observation is attributed to Italian economist Vilfredo Pareto who, in 1906, noticed that 80% of Italy's land was owned by 20% of the population. He then carried out surveys on a variety of other countries and found to his surprise that a similar distribution applied. He and others later discovered that this principle is proven in many other areas of interest:

• 80% of results come from 20% of effort
• 20% of your customers will account for 80% of your profit
• 80% of your sales come from only 20% of your total product line

Apply the 80:20 rule to the information you receive: 20% is useful, whereas 80% is not. The key is to identify and focus on that 20% and ignore or remove the rest completely.

The same is true of time expended for results achieved. Think of the benefits of applying the Pareto Principle to your time management and personal and business productivity!

Which one of these statements rings true for your business?

• 80% of your business comes from 20% of your customers
• 20% of your product or service range contributes 80% of your sales and likely 90% of profits
• 80% of customer complaints originate from 20% of the causes
• 80% of your business productivity loss results from 20% of the causes
• 80% of the value in the business is generated by 20% of the processes

The common approach to business is to squeeze every last drop out of each opportunity, to go "100% all-out," without consideration of the impact on time, productivity, and waste. Simple, time-efficient businesses recognize that it is fundamentally inefficient to go for the "whole pie" when you can get the majority of results for the minority of effort. With knowledge of the 80:20 lean simplification principles, you can concentrate on what wins you customers and successes in the most efficient manner and in the shortest amount of time. Look at your business and concentrate on the 20% that produces the 80% of benefit. Spend 80% of your time doing the 20% that really gets you results.

It’s not just about working smarter—it's about working smarter on the right things that will get you the best results. Pareto rules allow us to launch the products we know our customers need (such as the industry top-selling items offered in our new PCB Electronics Rework/Repair Production Chemicals line), and that our key distributor partners and sales teams can effectively sell. 80:20 gives us insight into developing value-added products that solve real problems for our customers.

Q Source, once again, thanks ACL Staticide’s Steve Allen for his Guest Blog contributions to The Q Source Resource.

For information about ACL Staticide products, please visit our ACL Staticide Department at QSource.com. You may also contact us via email or phone at 800-966-6020 and one of our associates will be happy to answer your questions or assist you with an order.

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If there's a product or topic you'd like to see The Q Source Resource write about please let us know. We'd also appreciate if you share this blog post with your friends and colleagues via the social media links below. If you have questions or comments about the 80:20 rule or about ACL Staticide products please leave us a message in the comments section.

For additional Q Source product information, reviews, how-to articles, and special offers please subscribe to our email newsletter.

Steve Allen's Previous Guest Blogs

• Volatile Organic Compounds & Evolving Regulations – Guest Blog
• Use Proper Balance to Create an Efficient, Cost-Effective PCB Cleaning Process - Guest Blog
• Why Clean "No Cleans?" Printed Circuit Board Flux Removal – Guest Blog

Volatile Organic Compounds & Evolving Regulations – Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide

Steve Allen, our guest blogger from ACL, this time focuses on the topic of VOCs and aerosol cleaners

An important topic today with end-use customers using aerosol cleaners, is the changing regulations regarding the VOC content and compliance of solvent-based products. Many customers are perplexed as to why manufacturers and suppliers don't already have this information on their product MSDS (GHS safety data sheets) and tech data sheets. At one time, the weight percent of all non-exempt chemicals in most products was listed on each product MSDS, but this information has been removed for several reasons. And, as most everyone knows, the regs are changing all the time.

There is an evolving Federal list of exempt chemicals along with many state and municipal lists of currently exempt chemicals. In some instances, these lists do not always agree. Additionally, there exists at least three EPA-approved ways to calculate VOC content. And, each method can yield different values for the same product. The choice of a particular calculation method can depend on the customer's location and the air quality regulations for their particular region.

It's important to review what a VOC is and why it's important. VOC stands for "volatile organic compound." These are chemicals whose vapors have been found to chemically react with nitrogen oxides (NOx, which are produced by auto exhaust, the burning of fossil fuels for power generation, and other industrial processes) in the air and in the presence of sunlight to produce ground-level ozone or "smog". The ability of certain chemical vapors to produce smog when sunlight makes them react with nitrogen oxides is referred to as photochemical reactivity. The direct emission of these vapors into the air defines the scope with which the EPA is most concerned. Thus, chemicals whose vapors are not photochemically reactive to form smog are considered exempt and are not included in the process of determining the amount of VOC ingredients in a particular product.

The federal EPA publishes a list of exempt chemicals and many states also publish their own list. A chemical that is listed as exempt on the EPA list may not appear on the individual state or municipality listings. A basic Internet search for methods of calculating VOC will generate literally 1000s of information sources and reference sites. VOC test results are used for a variety of purposes. These are predominantly for emissions fees, new source review applicability, and compliance with permit limits.

Most VOC and air quality/emissions permits do not specify VOC test methodology for purposes of demonstrating compliance with VOC limits. Currently, there are inconsistencies and a lack of guidance among states and EPA regions in implementation of VOC test methodology. It is technically difficult to specify any one single method for VOC measurement. This is why it is difficult to specify a simple value for the VOC content of most cleaning products. Without specific knowledge of the area of the country in which the customer is located, the EPA region under whose regulations they operate, if they are operating under a Federal NESHAP, the existence of state and local emission regulations, and the specific application or way in which the product will be used, it is difficult-to-impossible to list accurate and specific VOC information on a product MSDS.

Many states do not recognize all of the chemicals on the EPA lists as being exempt. Formal exemption of a chemical from VOC consideration may depend on how it is being used. California is generally the most extreme case and most industry there is moving toward water-based cleaning.

So, why are VOC determinations mission-critical today? Traditionally, VOCs have been used for conformal coating and various contact cleaning and flux removal applications. The properties of a conformal coating stem from the selected base resin and the various additives, while the solvents used in most cleaners come from an aromatic or aliphatic hydrocarbon base. These are included to optimize the performance of the cured coating or the formulated cleaner. Organic solvents are used to dissolve the base resin and reduce viscosity to bring the coating within a workable range. As such, the conformal coating dries by a simple solvent evaporation. Contact cleaners and flux removers function in the same manner.

Solvent-based conformal coatings are extremely versatile and can be applied in many ways, such as dipping, spraying, and brushing. By simply adjusting the solvent level, the viscosity of the coating can be tailored to the required application method. Solvents or VOCs are used for many different cleaning applications during PCB manufacture. Until recently, there has been a reluctance to change to alternative products for a number of reasons:

• Change required alterations to production procedures and equipment
• Solvent-based materials were very well established
• Alternatives did not have all the answers
• VOC limits on solvents were changing as were test methods

Cleaning is an essential process required at different stages in PCB manufacturing. The purpose of cleaning is to ensure good surface resistance and prevent current leakages which lead to PCB failure. Future markets see electronics getting smaller and smaller, and the requirement for high performance and reliability is stronger than ever.

Many manufacturers are turning to "no-clean" processes implying that cleaning is not required after soldering. In the "no-clean" process, rosin and activator are not removed prior to the next process such as coating or encapsulating of the PCB. Such residues, along with any other unwanted elements collected due to the missing cleaning stage, could cause issues with adhesion and possibly affect the performance of the protecting media applied. It can therefore be stated that even with advances in new technologies, such as "no-clean" fluxes, cleaning is still an essential multi-stage process within the electronics industry. Finally, there are also cleaning stages required for the removal of coatings and adhesives when re-work is necessary and for the cleaning of actual components and for maintenance of the production line.

Volatile organic compounds in cleaning and coating chemistries will continue to be a point of concern at the end-user level. Low VOC alternatives are available as are water-based options. Every manufacturer must maintain awareness of changing VOC regs and formulate products which are in the best interest of the environment, the industry, and most importantly, the end-use customer. ACL Staticide is committed to this effort as we develop and commercialize industry responsible and compliant new products.

If there's a product or topic you'd like to see The Q Source Resource write about please let us know. We'd also appreciate if you share this blog post with your friends and colleagues via the social media links below. If you have questions or comments about ACL Staticide products or about cleaning printed circuit boards and electronic equipment please leave us a message in the comments section.

For additional Q Source product information, reviews, how-to articles, and special offers please subscribe to our email newsletter.

Why Clean "No Cleans?" Printed Circuit Board Flux Removal – Guest Blog

by Steve Allen, VP Marketing and Innovation, ACL Staticide

Steve Allen, our guest blogger from ACL, returns with this article about cleaning “no-clean” fluxes.

Today, nearly half of all printed circuit boards (PCBs) are assembled with no-clean solder paste. The development of no-clean solder paste was initiated to eliminate the need for further post-solder cleaning of circuit boards. Yet, many electronics assemblers are still struggling with the process of adequately and effectively removing no-clean flux materials.

No-clean fluxes are now the most popular fluxes to clean in electronics manufacturing. Most manufacturers have designed and dialed in their assembly lines to run no-clean paste. And, they only clean the boards they want to clean, not always the boards they perhaps need to clean. Additionally, the flux residues left behind by no-clean pastes are more difficult to remove from PCBs than other fluxes. Since they are formulated not to be cleaned, the residues from no-clean products can be left on the board in unwanted areas with detrimental effects on the PCB. That creates a cleaning challenge if you need to clean off a residue that was not designed to be removed.

No-clean flux and solder residue on the board depends on the amount of solids in the material, the type of gelling agents, and various activators in the flux. The fluxes in most of today's no-clean pastes contain up to 60% solids. The lower the total solids, the fewer residues on the board. No cleans, in theory, contain lower total solids so as not to need removal/cleaning. Following the reflow process, the flux leaves a small amount of residue around the various solder joints.

There are several reasons to remove no-clean flux residues from PCBs. Historically, no-clean fluxes were developed as tacky resins, which inherently coated and stuck to all surfaces. The residue would gradually build up on the test pins. Manufacturers began cleaning no-clean fluxes when problems emerged with in-circuit testing. The latest technologies of no cleans are improved and no longer tacky, but still can interfere with signal transmission in most instances.

Also, no-clean fluxes can inhibit proper adhesion of conformal coatings. No-clean flux residues can absorb moisture in process. In any further curing processes, the release of any moisture can cause the coating to be separated from the board and incomplete conformal adhesion can occur. This can allow corrosive materials, carbon dust build-up, or moisture to penetrate under the assembly and cause corrosion, signal transmission problems, and component failure.

Today, no-clean paste manufacturers are aware that end-users are cleaning no cleans from board surfaces. The type of flux chemistry chosen can have significant impact on the cleaning process. To effectively clean and remove no-clean solder pastes and no-clean flux residues, a polar solvent or a solution of water and saponifier is necessary. Most no-clean pastes require an organic saponifier for effective flux removal, but some can be cleaned with inorganic saponifiers. No-clean fluxes that contain halides leave the most residue and are easier to clean. However, halide-free no-clean fluxes produce less residue, yet are more difficult to remove. In general, no-clean fluxes can be extremely difficult to clean, particularly following any reflow processes, as they can be baked on and tough to remove.

It can be vitally important to resolve any issues with no-clean technologies and their subsequent cleaning challenges at the forefront of the device design process especially with high-reliability products such as avionics or medical devices. In applications where cleanliness is critical, it is important to consult cleaning experts like ACL for the most effective, board-safe cleaning technology.

Q Source would like to, once again, thank our guest blogger, Steve Allen. We appreciate your contributions to The Q Source Resource and look forward to sharing your future articles, as well.

For more information about ACL Staticide products and options for flux removal, please visit the ACL Staticide Department at QSource.com.

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