The Science Lab
How to Find the Right Balance with Your Cleaning Chemistry
Total Balance: is having the right amount -not too much or too little- of any quality, which leads to harmony or evenness. It is a condition in which different elements are equal or in the correct proportions. The first and most important variable to look at is “what exactly are you cleaning.” Are you cleaning flux, solder paste, do you have particulate to remove? Are the soils organic or inorganic in nature?
Next you should consider these four important process variables: Time, Energy, Solvency and Temperature. Even small adjustments to these process variables can improve your cleaning and reliability outcomes. To help remember what the process variables that are in your control are, use the acronym T.E.S.T. All of these are critical factors to consider when getting your cleaning process balanced, effective and repeatable.
A balanced cleaning agent doesn’t just happen. It is built very intentionally with each building block serving a purpose and enhancing the effectiveness of the others. When choosing a balanced cleaning agent, check to see that it employs a good solvency package and functional additives such as: defoamers, buffers and inhibition technology.
A truly balanced cleaning agent:
- Is capable of removing all residues
- Is compatible with all materials present
- Will completely remove ionic contamination
- Is matched to the cleaning machine
- Is stable and effective for weeks if not months
- Is environmentally safe
- Is cost effective
When looking for the best cleaning agent, something to keep in mind is that a mild alkaline, balanced chemistry is much more stable as flux load increases. You should also consider the challenges of any cleaning process such as entrapment under fine pitch leadless components, longer wash times, material incompatibilities, bath life, and rinsing. To achieve cleaning stability in production you must look at developing process parameters that supply the same level of cleanliness on day thirty, day sixty, and day ninety as they did on day one. And, when looking to find the right balance with your cleaning chemistry, it is vital to keep all these things in mind. Luckily, KYZEN is here to answer all questions that might arise during this process. We are here to help find the best-balanced cleaning chemistry that works for you.
Additionally, learn more about finding the right balance with your cleaning chemistry the first time directly from a KYZEN cleaning expert; watch this Tech 2 Tech session by Global Key Accounts Manager, Jody Saultz.
How Clean is Clean? And How Can, You Be Sure?
Why would anyone consider cleaning in an era of no-clean? The main reason cleaning is so fundamentally important is because ionic contamination can cause dendrites which then in turn cause shorts that lead to device failure. This may seem like a simple nuisance, but is serious and in some cases, even life-threatening. Having the right test method to understand and know what is going on before a failure can happen is an excellent idea.
There are several common methods that are called out by IPC standards:
- ROSE Testing
- Ion Chromatography
- Surface Insulation Resistance
Visual may seem like an obvious method, or maybe not. We look at everything we make, but can that really be considered a test method? Yes, it can! While this may not be the best method out of the four previously mentioned when an inspector spots a problem, they can immediately act on solving the issue. With this method there is room for more errors…we are only human after all.
ROSE Testing uses a more scientific approach. The ROSE test has been around for a very long time but is under further review because how the science is applicable to what we are doing to find contaminants is changing because the flux people are evolving.
Ion Chromatography is another solid scientific testing method. When we are analyzing, it means we are trying to understand what is really going on. Typical IC methods focus on the whole board rather than a specific site.
Surface Insulation Resistance uses highly respected science and typically gets required for process validation. That seems to be the highest recognition of its effectiveness as well as applicability.
Overall, there are a variety of testing methods that can be used, but the best approach to ensure your parts are clean is to back up and really look at what is being measured. You must understand the fundamental science, and ask yourself, “Is this solving what we are worried about?”.
More information about How Clean is Clean can be found in this T2T video. Watch it here or feel free to reach out to one of our cleaning experts.