The hottest UV laser makes the processing size sma

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UV laser makes the processing size smaller

the definition of "medical processing" may lack precise meaning. However, in addition to infusion devices and bone nails, rough processing also provides opportunities for the workshop to enlarge other parts. Biotechnology is an example, which is still in its infancy. In many cases, as with the latest biomedical devices, special materials and their micron scale characteristics pose challenges to processing requirements, and milling and drilling are often incompetent. An unconventional processing technology that has been proved effective and repeatable, UV laser processing technology, has become the only means to process some biomedical components in some examples

medical OEM manufacturers often use this low-power, short wavelength laser system, and laser contract manufacturing plants also use it to manufacture complex biomedical components. Bill Kallgren, sales manager of J.P. Sercel associates (jpsa), said: these laser systems also need to find their own location in the so-called "typical" medical contract equipment processing workshop, which is placed together with Swiss lathes, machining centers or grinders. The general reason is not that these workshops lack purification or environmental control capabilities (the clean room environment is usually the requirement of biomedical processing rather than UV laser processing), but that the metal processing industry lacks knowledge of this special laser processing process. People in the metal processing circle are more familiar with high-power CO2 or YAG laser systems for cutting thick and thin metal plates

UV laser processing can be used in a variety of unique

thermal materials used in biomedical equipment for micron level processing

jpsa in Hollis, New Hampshire, UK, specializes in laser processing systems. The following information is generally a summary of our customers' many problems. Its laser processing system uses the pulse energy of UV laser to process small-size materials, such as glass, silicon nitride, quartz, polymers, ceramics and sapphire. The company not only designs and manufactures laser systems, its R & D and application department now has 13 sets of UV laser systems, but also plays the role of contract manufacturing plant. The factory serves many customers in the medical, electronic and semiconductor fields

undoubtedly, many ambitious medical contract manufacturing plants are looking for ways to expand production capacity and customer base. UV laser processing may be a means to enter the medical market. Paying attention to this technology and understanding how it is applied in jpsa factories is valuable for factories and manufacturers who are looking for alternative processing methods

new devices, new challenges

biomedical devices usually work at the cell level, which means that their component holes, channels and other parts are very small. The aperture processed by jpsa is generally between 1 micron and hundreds of microns. It is not surprising that the tolerances of aperture and related dimensions are also in the micron level. Although the thickness of the material usually does not exceed 2mm, the depth diameter ratio of the hole is usually quite large

the hole diameter in the polymer part shown in the figure is only 2 microns

the heat generated in the processing process is the great enemy of biomedical materials, and polymers and Teflon materials are particularly sensitive. This is the reason why these materials are not physically milled. Because these materials are easy to change color, melt and burn, any processing process should not make these materials produce high heat. UV laser processing hardly generates heat, so the material will not be damaged

laser type

UV laser cuts materials with a process called photo ablation. Continuous, high-speed repetitive laser pulses cut small and controllable amounts of material. A small amount of melted material evaporates in the form of plasma smoke. According to the different processed materials, the processing process will produce toxic gases, which requires effective gas collection and washing systems, such as activated carbon filters

jpsa uses two types of UV laser systems, one is excimer and the other is diode pumped solid state laser (DPSSL). In a word, the difference between the two lasers boils down to the difference in beam diameter (or laser spot size). The spot of excimer laser is larger than that of DPSS. Although the relatively large laser beam diameter of excimer laser seems not suitable for machining very small holes and components, the shape and size of this spot can be changed by mask, and only the passing light is allowed to act on the surface of the workpiece (in laser terms, this process is called near-field imaging). The shape of the mask is determined according to the components to be processed, and multiple components can be processed at a time. When drilling, this process of processing multiple holes at a time can ensure the accuracy of the position between the holes. Jpsa uses molybdenum to make masks for short-term needs or prototype processing. In mass production, the mask needs to be used for a long time, which requires a more durable and expensive quartz chrome coated mask

jpsa cooperates with MIT to create a new liver chip bioreactor for drug treatment research

this kind of polyimide device is processed by excimer laser system. Each 300 square micron flat

plate has 25 penetrating holes, a total of 20 square microns. These holes enable the device to simulate blood flow

excimer laser is very effective in blind hole drilling. Due to the high stability between pulses, the excimer laser of the experimental machine with the characteristics of stimulated constant displacement rate control is used to drill blind holes or cut micron level grooves, and the accuracy of its depth and width is ± 3 microns (sometimes it can reach sub micron accuracy). This precise depth control also allows the excimer laser to punch holes or make ellipses on one side of the needle. Using the depth control method, even if the laser is used to punch holes on one side of the needle, it will not affect the other side of the needle. It can also be used to remove selected substances, for example, to remove a specified portion of plastic from a coated conduit without damaging the metal under the plastic

because one of the gas components of excimer laser is fluorine, which is a toxic gas, effective gas treatment protocols are needed. For safety reasons, these gases are stored in a well ventilated place outside the laser system, and the monitored gas box is placed outside the factory, such as jpsa equipment

on the other hand, DPSS laser has high repetition rate and low operation cost as its characteristic. Unlike excimer laser, DPSS laser can focus the laser diameter into a small size. The combination of small spot and high pulse frequency (50000 Hz for DPSS and 400 Hz for excimer laser) makes DPSS laser more efficient in rapid cutting (slicing or cutting) process. The corner radius of the component processed by DPSS laser is equivalent to the spot diameter, with a minimum of 2.5 microns. Stimulated excimer laser with mask is usually used in applications requiring high corner machining

the groove on the cylindrical alumina component is drilled out with a single drill floor

, while the UV laser "turns" the groove with a width of 30 microns

the choice of laser type, wavelength and energy density mainly depends on the material, component shape and part thickness. Generally, shorter wavelengths (such as some excimer laser wavelengths as short as 157 nm) are very effective when used to remove certain substances and Teflon based substances, while longer wavelengths are more suitable for ceramics, metals and some polymers

punching problem

burr is a problem that almost every drilling process will encounter. "Burrs" are produced during UV laser processing. Although fingernails cannot feel them, they will still affect the performance of biomedical equipment. In the process of laser processing, the material transformed into plasma and removed from the surface will quickly cool into a solid state. If not collected by the vacuum pumping equipment of these laser systems, these substances will condense around the processed components. The condensed material is only a few microns high, but it is not small for a hole with a diameter of 25 microns. We can add a protective coating on the processed object to limit this condensation effect. In other words, condensate can be removed by secondary electropolishing or chemical treatment

taper exists in almost any laser processed component. For a typical laser processing process, the cone angle is between 4 and 15 half angles. 0-degree holes can be processed by complex methods, which need to manage the laser energy density and continuously change the focus of the beam (essentially adjusting the focus to the hole), but this method is time-consuming and therefore costly

as shown in the figure, the size of the UV laser system for production is equivalent to a small vertical machining center

toxic gases, a by-product of laser processing, must be properly treated

precise positioning

jpsa spent a lot of time developing precise positioning, especially for a lot of repetitive work. Its goal is to create a part bearing platform on which many parts are placed to ensure that once the part bearing platform is aligned, all the parts on it are aligned with the machine. Platform positioning can also improve labor efficiency. When laser processing parts, the operator can place the parts to be processed for another part bearing platform. In mass production, jpsa uses automatic part conveyor to place or remove parts on the part bearing platform

for many biomedical parts, the solid pollution of various works of the parts project is a big problem. The bearing platform can be coated with a layer of Teflon. Some users even require operators to wear special types of gloves when handling parts (such as latex free or powder free gloves). For other customers, this is not a big problem, because these parts have to undergo some post-processing in order to remove pollution

"it is very important to closely cooperate with the customer's quality control department to ensure the correct follow-up process." Mr. Kallgren said

do homework

with the integration of new technologies, the learning of UV laser processing system requires a certain amount of time. The best way to understand this processing technology in depth is to spend some time talking with the factories that are currently using this laser processing technology to understand the content of this alternative processing technology, so as to reduce learning time. (end)

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