Each year on 14 October, the members of the IEC, ISO and ITU celebrate World Standards Day, which is a means of paying tribute to the collaborative efforts of thousands of experts worldwide who develop the voluntary technical agreements that are published as International Standards.
Graham Naisbitt is Managing Director of GEN3 Systems Ltd. For over 50 years he has strived to improve the understanding of the cleaning processes, his dedication and enthusiasm has kept GEN3 at the forefront of the international standards for cleaning, he has spent decades leading cleanliness testing standards in a number of different standards organizations like IPC, IEC, and ISO around an assortment of testing methods, such as CAF, SIR, Graham and a team of volunteers from the IEC have just completed a new standard this year based on extensive testing of GEN3 Ionic contamination tester—Process Ionic Contamination testing (PICT).
The expectations and requirements of manufacturers and customers in respect of finished products are growing. The complexity of today’s cards varies from low voltage to high power, driving the need for cleanliness from both ends of the spectrum.
The difficulty has always been how clean is clean. In the context of circuit cards, cleanliness refers to a minimising of contaminating residues so that the residues will not interfere with subsequent function of the PCBA from an electrochemical standpoint.
Where this level is set, has been a concern for many years.
Contaminated circuits form leakage paths which distort signals (Cross talk), and in worst case shorts and opens (opens are mainly found on thin copper traces due to electrochemical corrosion).
Interestingly salts are non-conductive until sufficient moisture uptake converts the salt to a mobile electrolyte; this point is called the deliquescent point, which occurs around 75%RH@22°C for table salt.
Graham comprehends the current understanding of the ROSE test as a pass/fail of 1.56μg/cm² NaCl equivalent, but it does not reflect today’s small component designs such as 0201 chip components (let alone smaller 01005), micro BGA’s QFN’s and other bottom terminated components however, he also understands that manufacturing residues are a combination of product design, material choice, processes used, and even how and where you store your product.
Contamination is a constant threat not just from the obvious process flux residues, but various other sources, for example we all understand that unreacted flux residues are a common cause of field failure, however human sweat from handling is even more conductive than unreacted flux.
This is a complex and difficult problem that requires an understanding of the wash process and product field failure data:
- The contamination level has to be based on product field reliability data.
- The cleaning process will produce different cleanliness values depending on the product density, size etc.
- The test process has to produce repeatable and accurate results (six sigma).
- The cleanliness setting therefore is a process Ionic test based on what is achievable for an individual product using a wash process based on reliability data from the field. (PICT)
The GEN3 Machine
It was possible to achieve six-sigma-criteria for the repeatability and a sufficient reproducibility of recorded ionic contamination data at five different production sites worldwide. Using this approach, process control and methods of process optimizations are possible.
The Gage R&R project, based upon existing data, showed that there would be a 96.8% probability of at least one failure, but no outlier in the test data from any of the 5 instruments involved, was detected. Overall results show 8.96% Repeatability <10 results are required when tightened process control is necessary.
GEN3. Testing and measuring the electronics industry for over 40 years. For three generations, Gen3 have designed, engineered, manufactured, and distributed their test and measurement equipment into the electronics industry to shield their clients from failure in the field.
Their reputation for excellence has grown to a global scale. The team is made up of industry experts who work to set the standards around circuit testing, measurement, and compliance. They collaborate with key industry associations, offering our unique experience and expertise to educate all on what it takes to succeed. For product protection the preferred way is GEN3, where precision comes as standard, acting as a mentor and your front-line defender.
In the high-reliability arena, there is too much at stake to allow room for error. Testing must be finite and flawless. GEN3 understand the need for precision. Get closer to perfection by minimising your risk.
GEN3. Precision as Standard.
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