Todd E. Lizotte, president and CEO, Bold Laser Automation, and Dr John McAleese, president, McAleese Media
Reaching as far back as 2005, the escalating proliferation of nanotechnology was such that the highest echelons of US power were concerned as to the possible deleterious effects on the human condition. A hearing was called. The US Senate, keen to understand, quizzed experts in the field. What emerged was a consensus that although knowledge of the potential health issues arising from exposure to nanoparticles was in its infancy, it would be prudent to fear that as the technology infiltrated more and more all aspects of our lives, various work-related health problems would become commonplace if evasive action wasn’t taken to mitigate risk of exposure to such particles. It was explained that given as nanotechnology is based on the generation of inorganic and organic particles that were then rapidly reducing in size from 1 μm downwards, the likelihood of such particles entering our bodies, whether that be via the bloodstream or our lungs through breathing, was a very real threat.
The sad reality is that we’re in 2022 and as industry adopts more laser-based microfabrication technology, the concerns for operator health are as acute as they ever were. Industry faces the problem of ensuring that its specific processes and materials do not expose an employee/operator to harmful debris or smoke while they produce products or perform processes on the manufacturing floor. From a production facility standpoint, you need to be concerned about long-term exposure to debris, dust and gases generated during a laser process.
The importance of debris extraction
The importance of debris extraction cannot be underestimated given the years of data that show a broad range of health conditions, from trachea inflammation to bronchitis, have resulted from the inhalation of micro- or nano-particles generated during laser micromachining and microwelding.
Although not a fully thermal process, ablative laser micromachining produces fine particles and gases that are ejected in the laser plasma. It is essential that during any critical laboratory, industrial or automated processing, special care is taken to ensure a safe environment for those who monitor the processing or set processes up during tooling changes.
Imagine the possible consequences of particles from laser ablation processing getting into your operator’s lungs or biological particles generated during laser ablation of tissue interfering with the mucus membrane of the eyes, nasal cavity or throat. In the latter case, formation of warts is not uncommon, while in the former, it could be as dire as silicosis or black lung. These are terms once only associated with the deep mining of rocks or coal. In fact, in the case of processing crystalline silica, for example, silicosis can lead to fibrosis, a debilitating condition that can cause lung function impairment, resulting in breathing difficulties. This is where initial scarring becomes exacerbated by the formation of fibrous tissue.
Laser microwelding produces similar hazards depending on the welding method being used, tungsten inert gas (TIG) or metal insert gas (MIG), for example. This is because in addition to the formation of gases such as ozone, such processing also tends to produce spherical particles, ranging in size from 10 up to 400 nm. A case in point would be the welding of aluminium, producing as it does aluminium-oxygen compounds that manifest in the welding fumes. These particles are outgassed and present real danger if inhaled. Failure to protect operators opens up the real possibility of them developing irreversible aluminosis, an alarming consequence of negligence.
Custom extraction nozzles that affix to a just-in-time system for the removal of advanced material debris during laser processing.
Compliance with Occupational Safety and Health Administration (OSHA) standards
Many current laser systems feature a dust and debris mitigation system, which often requires venting into the facility vacuum system. However, their specifications introduce a great deal of ambiguity and uncertainty. It is not uncommon for it to be stated that 90 percent of the dust and debris are collected as a result of scrubbing the gases produced, but it’s usually not clear what those gases are nor, in the case of debris, what the lower limit of particle size removed is. What of the remainder? What is the destination of the 10 percent of debris not entrained?
Such information is critical in terms of complying with OSHA standards and answering questions likely to be posed by any serious, industrial health engineer visiting your premises who is concerned about air quality. In fact, if you’re intending to take your operation forward successfully, it will be of paramount importance that engineered filtration solutions are integrated effectively into your balance of plant.
Mitigating the hazards requires an industry shift
The long-term suitability of existing methodologies to mitigate the particulate hazards associated with laser micromachining and microwelding processing is highly questionable. Microscopic metal debris, gases or smoke tend to be entrained and filtered into replaceable filters. These are, almost affectionately considered, simple dust collectors and smoke eaters, but they have limited effectiveness.
Over the next ten years, as greater degrees of invention and sophistication are applied to the field of extraction, it is predicted that there will be a major move away from these dust collectors and smoke eaters to just-in-time particle removal systems to ensure safety and OSHA compliance for micro/nano particles. Eliminating potentially harmful material at the source of generation, or just-in-time, provides perhaps the greatest possibility of staff never coming into contact with or breathing in anything that might affect their wellbeing. It will be essential for customers to retrofit or augment 10-year-old filtration systems previously tailored to the materials they process.
A high-velocity extraction push pull nozzle for high-density interconnect chip package ablation.
Front and centre considerations for new equipment
In designing systems for advanced materials processing by lasers, a laser automation company must place health and safety front and centre, tailoring the design of extraction to the chemistry as well as particulate size or concentration.
In the production of microelectronic packaging involving high power laser systems, the selective removal of dielectrics and silica from printed circuit board (PCB) substrates by laser ablation should not result in either inhalable dust (a concentration in air equal or greater than 10 mg/m3) or respirable dust (4 mg/m3). To achieve this level of removal and entrainment, high-speed flow generated by a high-velocity vacuum must be employed in combination with particle traps strategically placed within the system. Customised nozzles directing the flow of entrained air within the processing zone ensure efficient removal of bulk material and fine particles. Further testing in a laboratory setting, where the laser plume is sampled using mass spectrometry, identifies gases that can be trapped or scrubbed.
Synchronised process solutions
Incorporating technology that simultaneously synchronises the optical beam delivery system with specific laser-material interactions such as motion paths and interpolated laser pulsing is commonplace, but the optical and mechanical synchronised with debris extraction is something quite new. This approach takes into consideration cyclonic action with plume dynamics, optimising and locating vacuum extraction exactly where necessary in the process to minimise residuals of any kind.
Laser systems must incorporate dynamic methods of debris, dust and gas mitigation if operators and employees are to remain safe processing modern materials.
Meeting the highest industrial standards
Machine builders and end customers themselves must ensure that by-product and waste mitigation regimes meet with the highest industrial standards, aligning with government safety legislation and OSHA standards surrounding operator protection. It should also be noted that there are many additional benefits to be attained by embracing more effective, extraneous material extraction, including the facilitation of greater process reproducibility and markedly reduced maintenance regimes.
Bold Laser Automation
McAleese Media