Precision in Every Micron: How We Engineered Our Own Screen Coating Solution

Precision screen printing does not forgive variability. A thin conductive path, a fine halftone, the sharp edge of a detail – each of these elements requires the emulsion layer to be exactly the same every single time. Not “more or less.” Exactly.

This is where the problem begins—a problem most printing houses solve manually. And this is the story of why we chose a different path.

Manual coating of screens with photosensitive emulsion is a process dependent on the operator: their experience, the pressure applied, the speed of the coating trough, and even their focus on a given day. In small-scale production, this might suffice. In production requiring repeatable parameters, it fails—especially when dealing with membrane keyboards, precision technical graphics, and components where coating thickness deviation is measured in micrometers.

Manual Coating: Where “Good Enough” Ends

Every manual pass of the trough over the screen is different. Different pressure, different speed, different angle—each variable translates into the thickness of the emulsion layer. Ghosting effects, uneven ink deposition, and edge bleed are the natural consequences of a process that relies on human touch.

For simple graphics and coarse meshes, variability is acceptable. The problem starts where requirements rise: fine halftones, narrow tracks, and precise interface elements. In such projects, any deviation in coating thickness is visible in the finished product as a loss of edge definition, unstable ink deposit, or reduced stencil durability.

An experienced operator can limit these effects. They cannot eliminate them—but they can recognize them. And that is exactly where this project began.

The Market’s Answer: Too Big, Too Expensive, Not Fit for Purpose

Commercial solutions existed. Automatic screen coaters are a mature category of equipment—featuring programmable parameters, pressure control, and intermediate drying systems. The issue wasn’t the availability of technology; it was that none of the available devices fit our reality.

High-end machines were oversized in both footprint and cost. Smaller models did not meet our technological requirements. After gathering quotes and conducting market analysis, the picture was clear: manufacturers design equipment for medium and large plants with the space and budget for massive infrastructure. Not for a facility where one of the main design constraints is the dimensions of a window opening.

That sentence sounds improbable, but it is true and accurately describes the scale of the challenge: the device had to fit into a restricted space. No available solution met this condition.

The Decision: We Build It Ourselves

Consultations with the R&D department (OBR) brought an answer that was hardly obvious but—after analysis—turned out to be the only rational one: we would design and build the device in-house.

The process moved in stages. First, the functional concept, then detailed component costing and budget approval. Next came technical drawings, consultations between the mechanical and electronic departments, and iterative design improvements. Only after all that did we move to prototype construction, testing, and production implementation.

Every stage was necessary to ensure the end result was not just functional, but also durable, intuitive, and tailored to the operator’s actual working conditions.

Mechanics, Electronics, Control – All In-House

The device’s construction is based on a rigid load-bearing frame and linear guides ensuring stable movement in the vertical axis. A motor-driven actuator allows for precise regulation of the trough speed; constant speed is one of the most critical conditions for coating repeatability.

The control system was developed entirely in-house. The operator panel allows for saving parameters for different screen types, while limit switches eliminate the risk of errors resulting from inattention. Operation is handled from one side of the device—which, in a limited production space, is not a minor detail but a prerequisite for usability.

The result is constant pressure and application angle, an identical number of layers in every cycle, and a stable coating thickness measured by the $Rz$ parameter (the average surface roughness height expressed in micrometers). This is a measure of quality that translates directly into the appearance of the finished print.

What Changed in Production

The implementation of the device brought results that are best described by what stopped being a problem.

Variability in coating thickness between screens: reduced. Defects in precision details: limited. Emulsion consumption: better controlled, as precise dosing eliminates waste from over-application. Operator fatigue from repetitive physical effort: lowered.

With fine halftones, an even emulsion layer leads to uniform drying and stable ink transfer. With thin tracks, a homogeneous coating limits element deformation during printing. For every type of screen: repeatability that cannot be achieved by hand.

Qwerty R&D – Internal Engineering as an Advantage

This project is an example of a mindset that is not an exception at Qwerty. When the market does not offer a solution tailored to real production conditions, you must develop the answer yourself.

The mechanics, electronics, and control systems were developed entirely by the R&D department. They created a device that entered the production line and works. Special credit goes to the team that merged three disciplines into one project: from technical drawing to a proprietary control system, and from dimensional constraints to daily ergonomics.

The machine works. It fits where it was supposed to fit. It does exactly what it was designed to do.

At Qwerty, we measure emulsion coating quality in micrometers because the end product that reaches the user’s hands cannot be based on “approximations.” Every project starts with a piece of transparent film. To finish well, every step along the way must be predictable.

The semi-automatic screen coater is proof that predictability can be engineered—even when you have to build it from scratch.