Laser marking is an incredibly versatile technology. With the correct choice of wavelength, power and pulse width – matched to the absorption and thermal characteristics of the target substrate – just about any material can be marked with a laser. The mark is permanent, unlike ink or labels. Plus laser marking is flexible and usually software driven supporting serial numbers and other variable or unique graphics.
At Coherent, we have the broadest range of products, including our market-leading PowerLine family of laser markers, and have a history of marking innovation, including the latest black marking for stainless steel and aluminum. With decades of experience supporting marking with virtually every type of laser and seventeen fully equipped applications labs strategically located around the globe, Coherent brings the expertise to partner with you every step of the way. We will determine the best match for your needs and your budget. We will fully prove the results in one of our applications labs, install the equipment and train your staff, and then provide you with the service and support to ensure you continue to get the results you need and expect.
Whether you need to create serial and batch numbers on semiconductor wafers, put UDI marks on medical re-usables, mark blister packs for pharmaceuticals, or create logos and graphics on anodized aluminum smartphones, a partnership with Coherent will eliminate the risk and provide the best marking solution for your needs.
There are several ways to mark colored, transparent or opaque plastics using lasers. Together with our decades of experience in marking applications, Coherent’s unmatched range of lasers and laser markers means that we can always provide a solution for your plastic marking application. A cost-effective marker or sub-system that is optimized to give you the results you want with the throughput you need.
A common method to create a permanent mark on white and other bright plastics uses a laser to drive a photothermal effect resulting in localized carbonization. This carbonization creates a dark mark that can be high contrast for easy visual reading by visual or automated inspection.
Dark plastics can be marked with a laser foaming method which leaves a bright mark for good readability. Here the photothermal heating locally melts the material and creates tiny gas bubbles. The resulting plastic “foam” has a lighter appearance.
Colored and dark plastics can be marked by localized photobleaching. Here either green (532 nm) or ultraviolet (355 nm) laser light directly breaks interatomic bonds in the polymer by a photochemical process, thereby bleaching it to produce a white or light mark. In the case of ultraviolet induced photobleaching, the process is often called “cold marking“, as there is no noticeable heating of the material.
Plastics with Additives
The use of laser-sensitive additives in plastics can generate considerable advantages. Additives in plastics are able to increase outline sharpness and contrast and thus enhance readability of the marking contents, e.g., for machine-readable codes. When used with transparent and semi-transparent materials, additives also result in excellent contrast uniformity and consistency. Plus additives in plastics increase the diversity of available product colors and are of crucial importance for the markability of certain materials.
Engraving on Plastics
Laser marking on plastics can leave a permanent mark by ablating (engraving) some of the material. This enables day & night marking of plastic parts which is widely-used in automotive industry and consumer electronics. Here the laser selectively removes specific layers from multilayer-coated transparent parts.
Engraving on Metals
A permanent mark is created by ablating (engraving) some of the surface of the material. The laser marker can be optimized to ablate any metal surface down to a pre-determined depth. Engraved marks in metal are exceptionally durable and can only be removed by mechanical grinding. This type of mark may be combined with oxidation or anodization to give a high-contrast appearance to the mark.
Selectively removing a surface layer like lacquer coatings or anodized layers is an ideal way to produce durable, high-contrast markings. This makes the base material visible by removal of the different colored overlayer by selective ablation.
Laser annealing is used with all metals, able to show a color change after exposure to heat and oxygen. The laser marker selectively heats up the workpiece surface until the annealed color change occurs. This is caused by the creation of surface oxides and can produce high-contrast, clearly legible markings.
For this application, we recommend: PowerLine F
Black Marking is a solution for direct marking of stainless steel alloys by changing the nanostructure to create a light-trapping surface. The ultrashort pulse laser technology does not introduce any significant heat and produces a high-quality, high-contrast mark regardless of the viewing angle. The process is particularly suited to the implementation of the Unique Device Identification (UDI) requirements in the medical industry. It can also be used with clear anodized aluminum surfaces without any effect on the outer anodized surface. It is particularly interesting for EMS-providers.
For this application, we recommend: PowerLine Rapid NX
Tactile laser marking creates a kind of recast on the top layer. This kind of marking can be found e.g. on all European EC cards where the name, card and account number is marked in this way. This is considered one of the key elements that makes these cards fraud safe.
On-the-fly marking refers to marking parts as they are moving and is well-suited to many types of production line settings without any time penalty. We have developed a proprietary solution for this type of marking which supports a wide range of processing speeds and guarantees high mark quality. Plus the process can be applied to both linear and rotary movement of the parts. In the latter case, the marking is applied on the surface tangentially without any distortion. And since the encoder signal for the position/motion adjustment is processed in real time, the marking process is automatically adjusted for any changes in the motion speed.
Labelmarking, Marking and Kiss-Cutting
Just-in-time label processing combines marking and kiss-cutting and is commonly used by the automotive industry and its suppliers. Within seconds, the laser marks specially developed labels on demand with alphanumeric text, serial numbers and bar codes. Both the marking contents and label shapes are freely programmable. After laser marking, the labels are cut out without damaging the liner (kiss-cutting).
Marking of Organic Materials
In some marking applications involving wood and other organic materials, the photothermal effect of the laser is optimized to cause both engraving and (slight) carbonization. The shadow effect of the engraving and the color change due to the carbonization combine to create a very visible mark.
The continuous miniaturization of semiconductor devices is pushing marking requirements to higher spatial tolerances in all three dimensions: smaller (xy) feature resolution and reduced (z) marking depth tolerances. In concert with growing applications such as adding data matrix codes, this trend is driving a need for new marking solutions that offer unparalleled performance in terms of speed, process control, and particle contamination avoidance.
Molded IC Packages
Depending on mold compound type and required linewidth we offer a variety of infrared and green laser markers. All laser markers can be equipped with a beam splitter and a pair of scanners and f-Theta objectives to allow marking of full trays and ICs on leadframe without the need for indexing. All our laser markers support matrix objects, a software feature that significantly facilitates marking each device with individual position offset correction, binning and serialization codes.
For this application, we recommend: PowerLine E
Lead Frames and Heat Spreaders
The marking of heat spreaders and lead frames requires lasers with a long pulse width in order to allow effective interaction of the laser beam and metal. The laser can be used to either engrave features into the metal or polish the metal’s slightly rough surface.
For this application, we recommend: PowerLine F
A laser system designed for wafer marking must meet the most stringent requirements. Wafer marking must produce machine-readable, very small, particle-free results with no negative influence on downstream manufacturing steps and still permit clear identification at the end of the process chain. Various methods such as soft marking and black marking exist and are applied either to the front or backside of the wafer. The Coherent marking software supports all common font types used in wafer marking. A smooth round beam and superior pulse stability are key requirements in wafer marking.
For this application, we recommend: PowerLine E 12 SHG