What is Dead Front Printing?

Dead front printing is the process of printing alternate colors behind the main color of a bezel or overlay. This effectively hides indicator lights and switches unless actively backlit. Then backlighting can be applied selectively to illuminate specific icons and indicators. Unused icons stay hidden in the background, calling attention solely to the indicator in use.

Dead Front Overlay Printing Methods and Substrates

There are two ways to illuminate a dead front overlay, each of which requires a different printing technique. The first method is to use LEDs directly behind each indicator or icon. This approach simplifies the printing process; since LEDs provide different colors, only a single color needs to be printed behind every icon.

Alternatively, selective printing can add different translucent colors behind various indicators and icons. Since the translucent ink behind the iconography gives the indicator its hue, dead front overlays printed this way can use almost any backlighting method.

Light diffusers are often applied between the lights and overlay to maintain consistency. Particularly with LEDs, diffusers can help eliminate hotspots, where one area of the letter or icon appears much brighter than other parts. Boyd makes custom diffusers for overlays depending on the necessary colors, light values, and external lighting environment to ensure that the backlighting is consistent.

While dead front printing is technically possible with almost any colored bezel or overlay, it’s generally seen on overlays and bezels printed with neutral colors; white, black, or gray hide unused indicators the most effectively. Dead front overlays are typically printed on polycarbonate, polyester, or glass, since they are easily back printed and hide icons effectively.

Developing Dead Front Control Panels with Boyd

When developing a new dead front overlay, experimentation is often necessary to get the perfect look. Given the breadth of possible lighting options, ink densities, color palettes, and substrates, maintaining a consistent look across an overlay often requires several prototypes to be developed. At Boyd, we have a state-of-the-art color lab, a light lab, and a full printing team to match and perfect colors. Within our color lab, spectrophotometers and spectroradiometers help define specific color values recommended for matching. Our printing team uses the light lab to specify the exact mixture and density of ink necessary for the specific substrate and required look.

Dead front printing is an excellent option for a wide variety of applications such as automotive dashboards, aerospace indicators, and Human Machine Interfaces (HMI). Learn how dead front printing can enhance your specific user interface by scheduling a consultation with our experts.

From selective printing to using clear conductive ink, we use several techniques to ensure consistent backlighting with capacitive touch (PCAP) switches.

Projected capacitive (PCAP) touch technology has become a popular user interface option for many industries in recent years. Not only do they offer a sleek, intuitive user experience, but the possibilities for backlighting a capacitive touch circuit are nearly endless.

While capacitive touch technology incorporates well with a variety of backlighting options, the design of the circuit is an important consideration. If designed improperly, the switches can potentially impede parts of the lighting, resulting in an uneven or inconsistent look.

How Can Capacitive Touch Circuits Affect Backlighting?

Capacitive circuits work by projecting a capacitive field and measuring any changes to the capacitance. This capacitive field is most commonly generated using circuits printed with conductive ink. Standard conductive inks, such as silver, carbon, or dielectric ink, can pose challenges when printing backlit PCAP circuits. The opacity of the inks can block backlighting and result in uneven lighting or shadowing on the switch.

Fortunately, there are several methods to ensure that backlit capacitive touch circuits illuminate uniformly every time. Below, we’ll be going over the three most common techniques we use at Boyd to ensure consistent backlighting.

Selective Printing:

One of the simplest ways to backlight a PCAP switch is by selectively printing around any backlit areas or iconography. When using an inexpensive carbon or other opaque ink, icons or symbols can be left unprinted within the design. As the backlighting rises through the switch, the light only comes through the unprinted area, resulting in a user-intuitive illuminated icon.

However, there are a few requirements to employ this backlighting technique. First, the switch area needs to be large enough for iconography to be left unprinted. In addition, there needs to be enough conductive ink surrounding the unprinted area to complete the circuit and result in an effective switch. This method is ideal for large or geometrically simple switch designs.

Backlighting Through Clear Conductive Ink:

For smaller or more complex switch designs, a solution that has been recently gaining popularity is using clear, polymer-based conductive inks (such as PEDOT ink). These inks run from translucent to nearly transparent and allow the circuit to be lit from directly underneath. Unlike a switch that uses opaque ink that potentially blocks lighting, clear ink conducts electricity the same way but allows light to pass through the circuit unobstructed. While transparent inks are more expensive than opaque alternatives, they can be applied the same way through screen printing.

Another advantage of using these inks is that the translucency can be altered based on the type of ink and thickness of the deposition. Less transparent inks also act as a lighting diffuser, thereby eliminating hotspots.

Altering the Capacitive Touch Stack-Up

Another solution is to engineer the stack-up so that the backlighting source sits above the capacitive circuit. While most capacitive touch circuits are backlit from underneath, rearranging the backlighting source (typically light-guide film or fiber optic bundles) to sit above the PCAP switches can ensure that the circuits do not impede any lighting.

While this is an effective method, the sensitivity of the PCAP switch needs to be tuned to accurately register inputs through the backlighting layer. Lighting hotspots are also a potential concern as the backlighting sits directly underneath the overlay, but this can be easily solved by adding a diffuser.

The above solutions are often mixed and matched depending on the design to ensure that each part of the interface is consistently lit. Boyd offers a host of different backlighting solutions for nearly any project. To discuss your specific backlighting needs, schedule a consultation with our experts.

From screen printing to digital printing to frit printing, there are several techniques used at Boyd to print on glass.

To ensure the success of any glass-printing application, there are numerous factors that go under consideration such as glass type, inherent tint of the glass, ink type, ink color, curing process, and environmental conditions. However, one crucial factor that needs to be determined is the print method. Glass can be printed on using one of the three techniques: screen printing, digital printing, or frit printing. While all these methods support different shapes, sizes, thicknesses, types of glasses, and allow the use of multiple colors, there are unique pros and cons that distinguish them.

Screen Printing on Glass

The first step is to specifically define what the device will be used for, as this can dictate which touchscreens are feasible. For instance, will your display be used for a military application where it may be subject to harsh conditions, or is the screen intended for an inexpensive toy where durability may not be a huge concern? Both situations would require screen technologies with different functionality, durability, input registration, and pricing. Once you’ve narrowed down the intended use for the display, the next step is to figure out which functionalities are necessary.

Digital Printing on Glass

Digital printing on glass functions like a regular inkjet printer, where the only requirement is digital art file to print. It affords greater flexibility in terms of changing designs at the last minute. Unlike screen printing, where any design variation requires the construction of a new screen, modifying an art file for digital printing is quick and easy. This makes it a great choice for prototyping and achieving faster time-to-market products. But it is important to note that the inks utilized for glass digital printing are thinner compared to the inks employed in screen printing. Hence, while working with light or pastel shades, multiple layers may be required to achieve a sufficient level of opacity. This can lead to an increased thickness and can pose challenges in the optical bonding process. In contrast to screen printing, where one color is printed at a time, digital printing also allows the printing of all the different colors at once. Digital printing on glass is currently undergoing continuous developments to accommodate more types of inks.

Frit Printing on Glass

Frit printing is similar to screen printing with the exception of the ink utilized and the curing process. A unique powdered-glass ink is screen printed onto the glass and cured during the heat tempering process. The heat fuses the ink to the glass, offering strong adhesion and making it difficult to remove or scratch the ink off. Since frit printing offers the highest durability out of all the techniques, it’s ideal for applications where the glass is regularly exposed to challenging environmental conditions commonly found in the defense, industrial, and eMobility sectors. However, it is also the most expensive printing method and therefore, not as frequently employed. While frit printing can be done on heat-tempered glass, it generally cannot be utilized for chemically-strengthened glass, as the glass thickness has to be greater than 2mm for the frit printing process. Frit colors are also limited to black, white, and some grays.

Bringing together the right mix of functionality and durability for your custom application, the experts at Boyd can not only help you select the most suitable printing technique for your glass application, but also support your glass printing and bonding needs from prototyping through production. To learn more about Boyd’s bonding solutions, schedule a consultation with our experts.

Lithographic printing, an offset printing technique, is based on the basic principle that oil and water do not mix. It is a process in which ink is transferred from a photographic plate to a rubber blanket, which then presses the image onto the printing surface.

What is Off-Set Lithographic Printing?

The first step in lithographic printing is creating the artwork on a photographic plate through a chemical process. Similar to the process of developing photographs, lithographic printing also requires the creation of a “negative” and a “positive” image. First, a thin aluminum plate is coated with a hydrophobic material so that it attracts oil (ink) and repels water. The plate is then selectively exposed to light, thereby curing the hydrophobic coating only in areas comprising the artwork. Finally, the coating from the remaining areas is chemically stripped off and the plate is ready for use.

The lithographic printing press consists of a series of rollers laid next to each other. The foremost roller transfers water, placed in a tray beneath it, to the photographic plate. The ink is manually applied to the second roller with a putty knife, which then wets out to the entire cylindrical surface as the roller spins and transfers the ink to the plate. The photographic plate, carrying the artwork, is wrapped around the next roller in the series. Given the immiscibility of ink and water, the ink adheres only to the artwork on the photographic plate, while the water adheres only to the remaining background.

On the other side of the photographic plate are two other rollers called the blanket roller and the impression roller respectively. The blanket roller acts as a medium to transfer the artwork from the plate to the substrate. When printing, a stack of printing sheets is placed on the top tray of the machine. A gripper grabs one sheet at a time and wraps it around the impression roller. The artwork on the photographic plate is imprinted on the rubber blanket roller, which in turn transfers it to the substrate on the impression roller. Then, the ink is cured by exposing the printed sheet to UV light. The process is repeated for every unique color in the image.

Advantages and Disadvantages of Lithographic Printing:

Ideal for high-volume manufacturing, a lithographic printer can run from 3,000 to 6,000 impressions per hour, with the largest sheet size being 18″ x 24″. It can produce detailed and intricate artworks with half-tones, gradients, or a four-color process. A four-color process uses a CMYK color module to create four separate dotted patterns that yield the required color when printed on top of each other. However, lithographic printing comes with its own limitations. It can only accommodate substrates with thickness ranging from 0.003″ to 0.020″. The printing system is not compatible with metallic or conductive inks. Also, the ink used is very transparent, and typically requires extra layers of printing for opacity.

Off-Set Lithographic Printing Services at Boyd

While lithographic printing is often performed on standard substrates such as paper and vinyl, Boyd differentiates our services by predominantly using polycarbonate, polyester, and aluminum. Allowing for extremely tight tolerances and consistently high-quality images, Boyd’s sheet-fed lithographic process is frequently utilized for printing graphic overlays and labels.
Lithographic printing at Boyd utilizes UV-cured inks. Boyd also offers custom color matching services to help customers achieve their exact specifications and uphold brand consistency. To formulate a custom color, the different colored inks are meticulously weighed, poured over a flat glass surface in carefully measured proportions, and mixed together using a putty knife. With projects requiring custom color matches, a small sample sheet is first tested on a machine called the orange proofer. This machine is a condensed version of the actual printing press, which allows Boyd to test the color and make necessary alterations before the final production run.

Boyd’s Printing Solutions:

As multiple factors go into consideration before selecting a suitable printing technique, Boyd works closely with each customer to understand the project needs and requirements to determine the best printing solution for every unique application. To learn more about our flex, screen, and digital printing capabilities, request a free design consultation with our experts.

To maintain the visual and functional integrity of your metal automotive trim ornamentation, including sill plates, liftgates, center stacks, steering wheel badges, and door trim, it is essential to use coatings and/or screen printing inks having superior scuff resistance.

Currently, there are many scratch and mar tests that are known throughout the industry and are employed by accredited testing laboratories. While these tests accurately gauge some real world environmental forces to which your ornamentation application will be subjected, they fall short of capturing the effects of one significant key real world destructive force: scuffing.

Boyd’s Scuff Resistant Coating and Ink Families:

Therefore, to ensure that our customer’s products could maintain their beauty and functionality throughout their life cycle, Boyd’s in-house chemists formulated a proprietary anti-scuff family of custom coatings and inks identified. Coatings and inks in this family withstand the real-world harmful scuffing forces that automotive trim components encounter regularly throughout their lifetime to preserve the original aesthetic and functional needs of the component for a prolonged period. The coatings underwent a variety of qualitative and quantitative tests in order to prove the superior scuff-resistant properties of this additive. One such rigorous test subjected the coating samples to aggressively brushing the surface with steel wool as the abrasive material at selected weights in multiple directions, known as our steel wool abrasion test.

Boyd’s scuff-resistant coatings are a significant improvement to our existing coating chemistry. The improved coatings and inks still have the same solvent resistance, stain resistance, and formability. This breakthrough coating technology can be applied to either aluminum or stainless steel constructions with low to high gloss without having any aesthetic effects, while maintaining its performance benefits in a wide variety of severe environments, from high heat to extreme cold. Our steel wool abrasion test results showed that the average product will scuff when subjected to two to three double rubs of steel wool pads when under a downward pressure of 3000 grams. Coatings and inks with the new additive could exceed 100 contacts with the steel pad under the same conditions with little to no scuffing.

During our battery of tests, we were able to validate that this family of coatings meets the industry standard specifications for the following:

Adhesion:

• Humidity resistance (GM4465P) – a test where the sample is exposed to 100% relative humidity at 38°C (100.4°F) for a specified time.
• Impact cross-hatch tape pull (ASTM D-3281) – a one-pound ball or cone is dropped at a specified vertical distance to an area that had been cut with a knife or crosshatch tool. The sample is tested with adhesive tape for any coating removal.

Scratch and Mar:

• Taber abrasion (ASTM D4060-1) – test samples are placed on a Taber rotating plate with a grit wheel of a specified
  grade and are abraded for a number of cycle turns with a given weight applied on each grinding wheel. The samples
  are graded by number of cycles for wear through point of the coating.
• A new type of scratch and mar test using steel wool – this test uses 000 steel wool that is rubbed back and forth with
  the weight of 3,000 grams applied. The end point is measured by the number of “double rubs” the sample could
  sustain before the coating began to wear through.

Solvent Resistance (GM9509P):

• This is usually tested by using a solvent that is specified by the paint supplier (commonly MEK). A soft solvent-saturated cloth is rubbed back and forth on the sample a number of times using the firm downward pressure of a gloved finger. The number of “double rubs” specified for a “pass” varies, but it typically ranges from 10 to 50 rubs.

Improved Film Properties Including:

• High durability in all environments of radiation and moisture
• Increased resistance to abrasion, scratching, and marring
• Improved adhesion and film flexibility
• Better impact resistance
• No detectable effect on accelerated xenon-arc exposure, helping to protect the color or gloss level fading over time

Boyd has years of process innovation and material science experience in the automotive industry. Learn more about our eMobility capabilities.

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