Expertise, Precision, Quality
When it comes to the most demanding applications, Steinerfilm brings decades of expertise from our heritage of manufacturing metallization and precision slitting equipment.
Our capabilities begin with a partnership with our customers to deeply understand their application - the performance parameters that enable them to deliver innovative and reliable products to their customers.
These are some of our core capabilities:
Metallized film capacitors today are primarily based on aluminum and zinc.
Aluminum is particularly suitable for robust designs and high Ohm metallizations due to its environmental stability. Aluminum layers can, for example, be metallized as low as 200 Ohm/sq. on polypropylene film. Purest aluminum metallizations, including heavy-edge and profile implementations, are particularly useful for DC capacitors and pulse applications.
Zinc metallizations are the optimal solution for low-frequency AC applications. Additionally, the metallization process can easily be controlled to achieve sophisticated resistance profiles. As zinc alone does not stick well to plastic films a pre-nucleation of aluminum is necessary. Typically 5% Aluminium is used However, any other ratio between Al/Zn can be made to customer's specifications.
Silver is an alternative for the pre-nucleation of zinc metallizations.
Gold is used for acoustic membranes and capacitors of high-end audio components.
Copper is successfully tested in capacitors with high frequencies and high currents.
Thick or Thin
Steinerfilm has your combination
Our heritage of indigenously built production equipment allows Steinerfilm to continuously optimize our machine capability to meet customer’s most stringent demands, including:
Process film as thin as 1.2 micron thick
Metallize a variety of flexible substrates – BOPP, PET, PEN, PPS, PEI, PTFE, flexible glass, non-woven, etc.
Deposit metal as thick as 500nm (subject to thermal strength of the substrate) to as thin as 5nm.
Provide very reliable high resistivity metallization (50-300 Ω/□) by employing inline control of layer thickness and subsequent roll processing techniques.
Slit film into very narrow to very wide widths.
Bring us your most demanding application - we don't have to wait for the equipment manufacturer to tell us if it is possible - we modify the machines to make it happen for you.
Summary Matrix of types of Profile Metallization
1. Constant Resistance
Metallized layers with constant resistance can be made with purest aluminum or zinc with a variable share of aluminum. Our process is capable of evaporating even large areas with an evenly distributed metal layer with the help of mathematical simulation models.
"Heavy-edge" is the classical solution to enable a stable and low resistive contact to the end-spray (shoop) of the capacitor.
We offer a wide range of choices regarding the metal ratio between the surface resistance of the heavy-edge and the active area.
3. Profile Metallization, Wide Heavy-Edge
The best possible compromise and optimization on low electrical losses and high break down voltages can be achieved by combining a wide heavy-edge with high Ohms on the surface at the free margin side. A wound capacitor must always have one of the two films with a good self-healing behavior using a high resistive area; typically 1/3 low resistivity and 2/3 high resistivity are designed over the film width.
In collaboration with our customers, we can precisely define the resistance profile into a repeatable specification.
4. Profile Metallization, soft transition, linear resistance
Metallization, with a defined profile of the surface resistance (= Rs), allows the minimization of the losses at each and every single point inside the capacitor (Pr = I² Rs).
During the design phase the tan. δ, self-healing, and breakdown voltage can be rated and optimized mathematically. A profile drawing with a precise resistance profile is provided to our customers.
The sketches symbolize the metallized layers of aluminum (yellow) and zinc (red). In the profile drawings we provide, the surface resistance is normally illustrated reciprocally.
Inner Series Patterns
Metallization for Inner Series Patterns
Series circuits of capacitors are not only realizable by discrete components but also directly integrated into the metallization. A compact capacitor wound element can be achieved, suitable for the highest operating voltages, using a detailed pattern of free margins.
An inner series design is generally the ideal solution if:
the increase of the operating voltage of the capacitor is limited by the thickness of the dielectric material (film thickness not available, too high field stresses at edges and surfaces)
the field stress (V/µm) of the dielectric material is to be limited, e.g. to avoid corona discharge safely
Steinerfilm offers a wide spectrum of free margin sequences, in-band or oil masking technology, that can be combined with every metallizing type plus segmented lines.
2-fold series patterns are normally symmetrically laid out and typically wound by using one film with a center margin and the other film with margins on both sides.
Multiple series patterns require a precise calculation, including the winding off-set, to ensure the voltages inside the capacitor are spread equally.
The example above represents a 13-fold series pattern of a film width of 120mm.
The margin sequence:
F2-M16-F2-M16-F2-M16-F2-M16-F2-M16-F2-M16-F2-R10 = 120mm
results in part capacities of an active area of each 7mm.
We will gladly support you during the design of series patterns for your application.
Masking / Segment Metalization
Metallization for Segments or Masking
Capacitor films where the metallized plane is divided by lines and structures are known as segmented or safety films. These patterns are achieved by an oil masking system during the metallization process.
At Steinerfilm, segmented patterns are designed according to the technical requirements of the customer. In practice, patterns can be divided into three different basic designs:
Examples of variations and combinations of these designs are Y, hexagon, or brick design.
We are also able to create “half-segments” where a wide area is fully metallized but the segmented patterns only start halfway towards the free margin edge. See example 5. below.
Effect and advantages of segmented capacitor films
1. Cut-off Lines
Free lines in the transverse direction (TD lines) guide the current from the contact edge to the free margin edge. This avoids the occurrence of circular currents and reduces the parasitic inductance.
In case of a dramatic failure, a local disconnection of the end-spray deactivates the faulty area.
2. TD Lines with Gaps
The interruption of the TD lines by electrical bridges avoids static charges on separated metallized areas. This static charge often can be noticed in a form of sparks on winding machines.
An interruption in the area of the heavy-edge can furthermore improve the contact to the end-spray layer.
3. T Segment
An essential part of the T segment is the barrier line in machine direction (MD line). The metallized bridges, also known as electrical fuses, are the gate between individual segmented areas and the face side contact. The current flow through the fuses is defined by the size or capacitance of the segmented area behind. An increased current flow results in over-heating and shrinkage of the dielectric material causing a mechanical break of the metal layer. In the event of a dramatic short circuit the appropriate metallized area is isolated and this initial fault will not trigger a disastrous “avalanche effect”.
4. Mosaic (Diamond) Pattern
These patterns are characterized by the relatively dense line structure with a high number of fuses. Being quite close to a faulty area the Mosaic pattern reacts fast in case of a failure and deactivates the faulty capacitor area proportional to the intensity of the failure. Mosaic patterns not only improve the safety of the capacitor; but correctly fine-tuned they will also improve the self-healing mechanism of the dielectric.
5. Special Segments
The variety of targets aimed to be achieved by segmentation requires new complex structured patterns. Parameters, such as leakage current, breakdown voltage, loss of capacity, safety function, reduction of inductance, etc. must be thoroughly considered. Even segmented designs to improve the C variation during the capacitor production are available.
We design segmented patterns based on your specification, but we also invite you to develop new, optimized segment designs with us in order to improve your capacitor performance.
In addition to precision metallization, Steinerfilm has expertise in various coating technologies.
Steinerfilm has the capability to deposit highly uniform and thermally stable thin acrylate coating at high speed in either substrate/metal/acrylate or substrate/acrylate/metal structure configurations.
For film capacitors, acrylate undercoat provides enhanced energy density and pulse power by improving the dielectric constant in addition to increasing substrate/electrode stability and improving clearing ability and end-connections.
For packaging applications, an acrylate overcoat can provide abrasion resistance for the metallized layer and can act as an environmental barrier.
Corrosion can readily occur in metallized thin-films when subjected to high temperature and high humidity environments. Steinerfilm has the capability to provide an inline top protective coating during metallization to stabilize the conductivity or surface resistivity of the electrode.
The edge-cut, normally in a straight line, of the capacitor film is done with the highest precision in the requested width. For a series of capacitor designs, however, this straight-cut offers disadvantages that can be minimized by Steinerfilm´s wave-cut technology.
1. Inside the capacitor, the mechanical contact between the end-spraying layer and the metallized film is an extremely important factor for a good dissipation factor and a high pulse capability. A contact edge in the wave-cut form in combination with an optimized winding off-set can significantly improve the contact of the end-spraying layer.
Flake-off of end-spraying: bad contact to the metallized film
End-spraying layer of a face side with wave-cut on the contact edge
2. Thin polypropylene films wound with a high tension are particularly prone to mechanical stress at the margin side. Damage can then easily occur on the adjacent metal layer. A wave-cut at the free margin edge spreads these stresses and reduces the risk at high operating temperatures or high currents.
Occurance of a stress zone
Compression damage at winding off-set without wave-cut
Available wave-cut types (margin and contact side)
Prototype and Custom Manufacturing
Bring us your most demanding applications - we'll bring our expertise and commitment to help you deliver market-winning products to your customers.
There are five primary factors to consider when creating a specialized film:
Our legacy in metallization machinery allows us unparalleled expertise working with any film type and thickness, the right choice of the evaporated metal, the metallizing profile, and geometrical execution of the film.
Our designs consider the smallest details to optimize the reliability and performance of the metallized film in the end product.
We'll work with you on prototype production runs, support you with value-add manufacturing services (such as slitting, secondary processing, etc.), whatever it takes - Steinerfilm is ready for you.