FREQUENTLY ASKED QUESTIONS
How do you ensure the stability of the template and that it doesn't slip when it is only secured with tape?
Typically using the tape on the edges works fine. For additional stability, a double-sided adhesive is recommended, but as the mechanical forces tend to diffuse, not much strain is introduced on smaller pieces of tape.
When mounting the imprint template using tape on the edge, you have to place the tape under tension, so there is no movement of the imprint template itself. Placing the imprint template under tension will prevent slip.
The soft PVC is slightly adhesive by itself, so you can mount the imprinting template on it directly. However, the excessive resin can flow outside the imprinting template area. We, therefore, recommend using a protective/sacrificial foil on top.
Any resin waste tends to happen at the start of the imprint process. During the operation, the pressure will stabilize it during the imprint process itself.
Is there any video about the mounting method?
Yes, we have an instructional video available on our youtube channel.
What are the removal methods of residual glue after embossing? Can residual glue be removed cleanly when you are done with the imprinting template?
If your imprint template is on a sacrificial foil (included with our
HoloPrint® uniA6 DT), and you are using the double-sided adhesive tape - the foil itself can be removed from the cylinder, as it is the easiest method to manage without any risk that cleaning chemistry is exposed to the imprint cylinder.
If your imprint template is on the soft PVC, most likely you will have issues from the adhesive tape, which is why when mounting on the soft layer, we advise against using adhesives, since it is slightly adhesive itself. We also recommend using only low tack tape to secure the edges.
We need to imprint the following structures: Linear Gratings - period:>100nm, height:100nm; Holes on Square Lattice - period:>100nm, height:100nm; Hexagonal pillar array - Period（Gap+Diameter）: 230μm, Diameter: 200μm, Height: 30μm; Pillars on Square Lattice - period:>100nm, height:100nm. Can the HoloPrint uniA6 DT reach the requirement?
Yes. Tests and trials are always recommended to find the right parameters and materials.
What about reproducibility? Is there any difference in quality after 10 or more imprints? Is there any experimental data?
This depends entirely on imprint templates, imprinted features, inking methods and chemistry used.
We experience with imprint templates used in our machines that have done thousands of imprints. Verification has been done by optical methods, measuring the diffraction efficiency of holographic features (which would correlate with changing dimensions of the nanostructures). No SEM data are available at this time.
In our experience, degradation is due to buildup on the imprint templates.
Could you tell me more details about your optical engine?
The optical engine is based on LED technology which we expect will last a lifetime (>40.000 hours). Option for the integration of water cooling is integrated into the optical engine and a simple water-cooler can be attached. Normally, that will not be necessary and a 2 step alarm and security shutoff system is also integrated into the optical engine.
How is the substrate attached to the “moving stage”?
The substrate would be fixed with either tape or not at all, friction could be sufficient to keep the substrate fixed, the latter would be substrate-dependent.
Can I imprint on uncoated paper/foil/glass plates?
In principle, it works on any printable surface/material, though adjustments might need to be applied for uncoated paper and foils, based on test results.
Who is supplying the prepress?
You can make it yourself or get prepress material or finished prepress from Stensborg. We have years of experience.
What is the maximum imprinting area?
We have delivered imprint rolls with imprinting area up to 420 x 628 mm.
Which solvent could we use to remove uncured DM 56 and X166b resist? We just need a solvent in which the resists are soluble. Would Acetone or EBR solvent (PGMEA) work?
We have successfully used IPA, and Acetone should also work but that is of course depending on what base substrate the none-cured resin is applied to and your potential application work afterward.
For our industrial roll-to-roll machines we also used industrial-grade environmentally-friendly UV cleaner on metal and rubber parts that is in contact with non-cured UV resins. It is a liquid which is normally bought in 10kg containers. We would recommend you make a few tests initially with IPA or/and EBR solvent to see if that suits your purpose.
There was a significant buildup of polymer on the soft backing layer - how do we avoid that?
Here are some things we can recommend to you:
Avoid resin on the soft impression layer in the first place.
We highly recommend mounting the imprint plate on top of the protective foil that acts as a sacrificial foil. Using a sacrificial foil this way is the most straightforward, and reduced the risk of damaging the soft impression layer, and in the case of a problem or a misprint, the foil can be disposed of and replaced easily, instead of spending excessive time to clean the soft impression layer. Apply tension in the running direction in the imprint plate when mounting the plate manually by hand.
Alternatively: be sure that there is an excess edge if you are placing an imprinting plate directly on the soft backing layer so that the imprint plate covers the entire active area of the process - at least 200mm in length. This ensures that tape used to secure the edges - is never under imprinting pressure. The extra length of the printing plate will also ensure that excessive ink can not come in contact with the soft layer.
Is it important to have a bearer stripe? I do not have bearer stripes in the right dimensions for my application.
When imprinting on thick and narrow substrates, for instance, a glass slide: it is necessary to have at least an improvised quasi-bearer stripe, if you don't have long enough pieces to make such.
This could be done by starting off with a double-sided adhesive on a larger plate that would fit on the machine, akin to the dimensions of the provided glass plate (155mm x 315mm). This material could be polymer or glass. Then, placing a row of the substrate materials on the tape would make a somewhat functional bearer stripe. Otherwise, if you don’t do this with thicker materials, you will leave marks on the cylinder and risk destroying your imprint.
The images, attached below, show the best ways to make this compound bearer-stripe area (green shows the area of the double-sided adhesive, black is the material, and red showcases your imprint sample) where having an overlap increases the stability of the imprint, so there are no “jumps” where the cylinder could catch unexpected damage.
Placing the bearer stripes at the edges of the area helps to:
When adjusting the thickness, it helps to align the cylinder to the plate.
Since the machine is driven by the plate, having contact between the cylinder and the moving plate is necessary at any given position. Otherwise, you risk crashing your substrate into the cylinder.
It stabilizes the machine during the imprinting process, where there are no large jumps of thickness, which would correspond with jumps with force and load. This will leave an influence on your final imprint.
What tape should I be using for fixing the edges?
We recommend using 3M Scotch 810 tape.
Is the print plate of the starter kit PDMS, or other Polymer? Is it possible to design printing plates according to customer requirements?
The chemistry we provide makes it easy to design imprinting templates according to the customers' own requirements.
The imprinting template:
The imprinting template comprises a pre-defined surface relief structure, the surface relief structure being arranged to be imprinted on the sample substrate.
The imprinting template can take any suitable form. However, in general, it should be formed from a flexible material which is operable to conform to the curvature of the cylinder. It can be formed from any suitable material transparent for 395nm, for example, a polymeric material such as:
The imprinting template is placed on the cylinder in a position that will ensure that it is in register with, and rotatably aligned with, the substrate so that when the movable plate moves the substrate to the nip, the imprinting template will engage correctly with the sample substrate and transfer the desired pattern to the substrate.
Cyclic Olefin Copolymer (COC)
Polyethylene, Polymethylpentene (PTX)
a light-curing resin/polymer
Other useful information
We provide the HoloPrint® uniA6 DT as an R&D tool with starter packages of materials. We do not provide the HoloPrint® uniA6 DT as a regular production process or machine with guaranteed results and client acceptance schemes for various NIL applications. That involves a completely different business setup on which we are happy to elaborate if need be.