We’re actually doing a fair bit of research into this question because while the prevailing wisdom suggested DLC is always dark gray or black, some brands have started offering “Gold DLC”. The emergence of other carbon-based coating technologies could potentially further muddle the answer. We’re going to get a direct response from the brands communicating their recent coatings as Gold DLC to see what the heck is going on there, and then we’ll dive deeper into futuristic coating technologies more next year (we have some interesting, first-hand research projects coming up).

Estimated refractive indexes show well agreements among almost all Si–DLC coatings, instead of the differences of coating conditions. Generally, the longer coating time or slower coating process makes the higher refractive index in near infrared region. Estimated band gap of a Si–DLC coating was about 1.5 eV. The developed Si–DLC coatings must be useful as not only protective but also decorative coatings.”

The coating is formed of vaporized solid materials with a typical PVD process, bound to the watch casing in layers inside a heated vacuum chamber. Depending on the type of material used to coat the watch case, different colors can be achieved, DLC uses carbon as the coating solid, so it only comes in shades of black. Vaporized carbon atoms are blasted onto the watch and cooled down very quickly. So, to attempt to clarify, DLC is a coating applied using a PVD process. Got that? Excellent work — A+.

NorlandOpticalAdhesive

The use of V-groove structured substrates is common for passive alignment of fibers. Instead of connecting several single fibers to the PIC one by one, they can be pre-assembled by using V-grooves. The whole part, consisting typically of 12 fibers or more, can then be connected to the PIC in one step. The fibers are kept in the V-groove by bonding a lid on top. DELO adhesives can be dispensed before joining the lid or afterwards by an underfill process.

Thanks to their universality, LEDs are used in a wide range of applications. They offer manufacturers great design freedom and enable new types of lighting concepts – in consumer electronics, the automotive industry and sensor technology.

So I’m yet to find any real conclusive proof of this technique being used for case coating in watchmaking (and I haven’t received a response from the brands I’ve contacted asking them to clarify the term “gold DLC”) but I found this interesting and wanted to share it with the community as part of our ongoing quest for truth:

Norland adhesive

DLC is an abbreviation, so if you’ve been trying in vain to form some kind of weird word out of those three consonants, you can stop. DLC stands for “diamond-like carbon”. As the name suggests, DLC coatings use carbon to achieve a diamond-like layer. Sounds fancy, right? Well, like diamonds, a DLC coating is actually harder than raw steel. In turn, that means that watches with a DLC coating benefit from increased durability and scratch resistance. Despite only being a few microns thick, a DLC coating is pretty badass. By way of reference, a human hair is, on average, 50-70 microns thick. The average DLC coating is around 2-4 microns thick. All that strength and protection in a barely-there layer of… Well, what actually is it?

Attaching the PIC to a substrate or interposer is essential for photonic packaging. Reliable bonding with low CTE and sufficient bond strength are required. Additionally, DELO offers adhesives with light fixation that are beneficial for high accuracy and reducing the cycle time.

Opticalepoxy

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Many different coatings are available to brands, each with its own quirks, benefits, and negatives. Today, I’m looking at one of the most common coatings, which is DLC. Whether you realize it or not, you will most likely have seen a DLC coating on a watch before. Do you know those stealthy, all-black cased watches? The chances are, they use a DLC coating to get that blacker-than-black finish. However, the real question is, “What is a DLC coating, and how does it work?”

DELO’s optical-grade materials offer an almost complete freedom of design, enable complex device architectures and are easy to fabricate at the same time.

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In vehicles, this technology is also used in microlens-based ultra-compact projection systems for headlamps or decorative and functional lighting applications that can be integrated anywhere in a car.

As we already know, DLC stands for diamond-like carbon, and that’s precisely what it is — carbon. DLC is applied to the watch case using a PVD process. What’s that? Another abbreviation? Don’t you know it! The chances are that you’ve also come across PVD in your journey through the world of watches. To make things more confusing, it’s not uncommon to see the two terms used interchangeably when they are not one and the same. PVD stands for “Physical Vapor Deposition”, and it is not a coating itself. Instead, it is a process of applying a coating.

DELO's adhesive portfolio for optoelectronics includes transparent and low-outgassing, tension-equalizing and electrically conductive adhesives, and die attach to structural bonding. Optical coatings with customized properties regarding transmission, reflection and absorption, as well as encapsulants to protect sensor packages, are also offered by DELO. Users can choose from products with different curing mechanisms depending on the relevant component geometry or substrate combination.

Photonic integrated circuits (PIC) play a major role for integrating optical functions like signal processing, data transfer and sensing to electronic devices. A PIC is an advanced system on a chip in which multiple miniaturized optical components such as amplifiers, modulators or filters are combined. Operating in the optical/IR range of the EM spectrum (380 – 1650 nm), they allow very high bandwidth and data transfer at high speed.

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All DELO functional adhesives and sealants in its DELO PHOTOBOND, DELO DUALBOND and DELO KATIOBOND series are particularly suitable for highly automated high-speed processes with high outputs.

UV adhesive for glass

Sinn’s fully tegimented U2’s that are PVD/DLC’d look to be pretty industrious. I think that’s the only brand I would sorta trust if buying a fully DLC’d watch.

“Diamond-like carbon (DLC) is widely used because of its good properties. However, the color of DLC is usually dark brown or black. Recently, we have made fairly transparent Si contained DLC (Si–DLC) coatings in visible light region. The fairly transparent Si–DLC was made by using our original bi-polar pulse type plasma based ion implantation (PBII) system, with recently introduced high slew rate pulse power supply. The colors of metal sample surface were uniformly changed as subdued red, yellow, subdued green and subdued blue or violet, with the change of Si–DLC coating’s thickness. The colors come from the interference between reflected lights at the surface of the Si–DLC coatings and the surface of the metal samples. The colors were also changed with the angle of glancing.

Watchmaker jargon can be difficult to understand. You read a review about a watch you’re interested in, but there are lots of words being used that don’t make a lot of sense. Sometimes in the watch industry, we forget that people of all experiences are trying to enjoy the same products. We can be a little non-inclusive when it comes to our vocabulary, instead preferring to stick to traditional verbiage rather than layman’s terms. So with that in mind, what is a DLC coating?

UV imprint of single optical elements is just a small aspect of wafer-level optics. Its true power comes into play when full optical systems are manufactured in parallel on wafer-level. Besides the optical elements such as lenses or DOEs, an optical system needs additional components, for example spacers, apertures and a housing. Wafer-level optics deals not only with fabricating each single element, but also how to stack these elements to form the full system.

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Optical materials and adhesives play a key role in the development and production of wafer-level optics. They are not only used to secure and protect optical elements such as sensors or LEDs. DELO's optical materials are also used to produce microlenses and diffractive optical elements (DOE) which are used in the flash module of smartphone cameras or as microlens arrays in projection systems.

Short distance PIC to PIC or fiber to PIC connections can be achieved using photonic wire bonding. Similar to electrical wiring, an optical wire is used for interconnecting already assembled PICs and/or fibers. The photonic wire bonds can be 3D written by means of two-photon polymerization (2PP). For protecting the tiny wires, DELO offers a low index of refraction (RI) adhesive cladding that allows wave guiding by total inner reflection.

Now, you may have also heard concerns about coatings and the truth behind their scratch resistance. While we have established that the DLC coating offers additional resistance to the scuffs and scrapes that everyday life may throw at it. But, what if you really give it some welly and whack it on a brick wall? Will the steel underneath peek out through the open wound? If so, it’d be pretty hard to miss, no?

In addition to toughness, optical materials and optical adhesives must also display thermal and UV stability, low outgassing and low shrinkage. DELO offers an extensive range of specially adapted adhesives for these requirements.

Sinn’s fully tegimented U2’s that are PVD/DLC’d look to be pretty industrious. I think that’s the only brand I would sorta trust if buying a fully DLC’d watch.

Micro-optics and nanostructures are key technologies for the latest miniaturized optoelectronic components in smartphones, smart glasses and vehicles. Examples used in consumer electronics include microlenses in time-of-flight or ambient light sensors, diffractive optical elements (DOE) for structured light generation and surface relief gratings with nanometer precision in diffractive waveguides that enable new applications like 3D sensing or augmented reality glasses.

Packaging and optical interconnecting on chip-level as well as on board-level is technically very challenging. Low coupling loss requires very precise active alignment capable adhesives. Post-processing like the assembly of electronic SMDs by typical reflow processes underlines the need for highly reliable materials.

OpticalAdhesive Film

There are several approaches to couple a PIC with optical fibers. In general, single mode fibers with core diameter of just a few microns are used, requiring very high precision active alignment. The fibers can be directly bonded to the PIC with the adhesive within the light path. Using the adhesive outside the light path by bonding the fiber to an interposer is typically followed by filling the gap between fiber and PIC with an optical adhesive that matches the index of refraction (RI), minimizing the transmission loss caused by Fresnel-reflection. Another approach is to use microlenses on the PIC, allowing higher tolerances or enabling contactless connection (expanded beam connector).

And there you have it in a nutshell: DLC coatings 101. You can feel more confident knowing what you’re signing up for when buying a watch with a DLC coating. Do you already have watches with coatings in your collection? Tell me about them and how you’re getting on with them! I’m interested to hear about your experiences.

Well, with some types of PVD coating, this is potentially a legitimate concern. It can and does happen. Over time, the black coating will scratch, and you will see the exposed steel. But, fear not, with the DLC coating, things are a bit different. Thanks to the diamond-like properties of a DLC coating, you don’t have to worry about this happening to your watch. The coating stays put and does not wear off anywhere as quickly as a more conventional PVD-type coating. That’s not to say that you’ll never be able to damage it, so don’t actively try to test this out. It just means that a DLC coating is considerably more protective and hard than other lesser coatings.

Traditionally, watches are made of metal. Sure, there are watches made from non-metal materials, but usually, nine times out of ten, the watches we see are made of some kind of metal. Of those metal watches, the vast majority are made of good old stainless steel. Steel is usually a silvery/metallic color, right? Of course it is! I know that’s a stupidly obvious statement, but bear with me. What happens when brands want to make a watch with the benefits of a metal case but in a non-traditional metal color? Well, that’s where we get into the realms of coatings.

UV-curable polymers are increasingly used for mass production of optical elements via nanoimprint lithography. A matching index of refraction, high transmission and balanced thermo-mechanical behavior, paired with an overall excellent reliability, are their most important features.

Adhesive bonding is a demanding joining technology. To successfully solve bonding challenges, you need a good understanding of the basics and special features of this technology. Build up valuable knowledge with the help of our "TECH TALK" webinars!

But: it`s still a coating! With the soft material behind, mostly 316L, it will come off by scratches, hits and so on. I`d rather use a decent hard steel though, and even 904 is ridiculous…

Actually… yes. There are a couple of microbrands who offer watches that have a clear scratch-resistant coating on stainless steel. Off the top of my head, Straton Watches offered such a case… Heroic 18 was another one.

Functional adhesives play a key role in the manufacture of LED packages. They ensure brilliant, homogeneous diode illumination and fast production. DELO has developed a host of suitable products for both first- and second-level packaging. In first-level packaging, the adhesives are applied in the immediate vicinity of the LED semiconductor. In second-level packaging, the adhesives are used to join lenses, cover disks or housings that are used around the LED module.

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Coating yes, but DLC as far as I am aware. For example RZE uses its clear Hex coating on its watches. RZE’s coating is a different PVD coating rather than DLC specifically. As far as I am aware the clear coats will use PVD or CVD as the coating process, but the coating is not DLC.