Most contract electronics manufacturers will tell you they offer conformal coating. However, fewer can tell you whether your boards will be coated by hand, by a precision automated system, or both, depending on what the job actually needs.
At Key-Tech, we offer both, and our conformal coating services in the UK are built around that flexibility. Specifically, we have invested in a fully automated coating cell alongside a dedicated manual spray booth, which means we can match the right process to the right product, rather than forcing every job down the same line. As a result, our conformal coating services give customers genuine choice about how their boards are protected.
In short, conformal coating is a thin polymer film applied to a populated PCB to protect it from the environment. Typically, thicknesses range from 25 to 150 microns, thinner than a human hair, but enough to make a significant difference to long-term reliability.
Importantly, it guards against moisture, dust, salt spray, chemicals, fungal growth and the kind of low-level contamination that quietly ruins electronics over time. Therefore, for any product going into a harsh, humid or unpredictable environment, conformal coating is not really optional, it is part of building it properly. Industry standards published by IPC (the global association for the electronics industry) set out the requirements we work to.
Full background on the process is on our Key Capability page.
To begin with, no two boards are the same, and good conformal coating services have to reflect that. For example, some boards are dense, multi-layer assemblies destined for high-volume runs. Others, on the other hand, are low-volume, complex prototypes with awkward geometries and components that need careful masking.
In fact, trying to coat both with a single approach leads to compromises, either slow throughput on simple jobs, or poor edge control and overspray on complex ones. However, by running both manual and automated conformal coating in-house, we can pick the right tool for the job every time.
For repeat production work, and for any job where consistency matters most, we run two Nordson Asymtek selective coating machines: an SL940, installed in 2021, and a C740. As a result, we have real production capacity rather than a single point of failure on the automated line.
The SL940 is our primary machine. First, it’s fitted with three interchangeable heads: an SC280 film coater for wider application widths, an SC400 precise coater for narrow areas, and a DV05 dispense head for coating gel. In addition, fan width control, a heated recirculating fluid circuit on the SC280, and a laser needle finder on the SC400 and DV05 give us the accuracy and repeatability we need for production runs.
In practice, that translates into something simple for our customers: clean, repeatable edges around connectors, test points and keep-out zones, with little to no manual masking required on most boards. For engineers who want the full technical picture, the specs are in the box-out below.
TECHNICAL SPEC: Nordson Asymtek SL940
| Installed | 2021 |
| SC280 film coating head | Application widths from 6 mm to 12 mm, heated recirculating fluid circuit, fan width control |
| SC400 precise coating head | Application widths from 2 mm to 4 mm, laser needle finder for placement accuracy |
| DV05 dispense head | Coating gel dispensing for selective protection and edge definition, laser needle finder |
| Maximum board width | 400 mm |
| Maximum coating area | 297 mm (X axis) × 398 mm (Y axis) |
| Smallest coating feature | A dot approximately 2 mm in diameter |
| Coating material | HumiSeal 1B31S, air-cured acrylic |
| Coating standard | IPC: 25 to 125 microns (0.025 to 0.125 mm) coating thickness |
| Current characterisation | Measured deposit of 0.049 to 0.063 mm, well within IPC limits |
As you saw in the spec box above, both automated machines run HumiSeal 1B31S, an air-cured acrylic conformal coating. Specifically, it was chosen for good reason:
Above all, that last point is critical for our defence, aerospace and medical customers, because coating qualification is part of the supplier audit, not an afterthought.
Automation is not always the right answer. For prototypes, low-volume builds, complex board shapes and rework, manual spray application gives us the control and flexibility a machine cannot match.
Specifically, our manual coating is carried out in a dedicated SCH Technologies spray booth with downward-draft extraction, ergonomic turntable and HVLP spray gun technology. In addition, the booth includes integrated UVA lighting so operators can verify coverage in real time as they spray, not just after the fact.
Overall, this setup gives us the best of both worlds: skilled hand application backed by a controlled environment that protects both the board and the operator.
Ultimately, conformal coating is only as good as the inspection that follows it. For example, a pinhole, a missed edge or a thick build-up that traps contaminants can quietly compromise reliability for years before it shows up as a field failure.
For this reason, every coated board at Key-Tech is inspected in a dedicated SCH Technologies IB100 UVA inspection booth. Importantly, the HumiSeal coating fluoresces under UV, which makes it straightforward to verify uniform coverage, identify any thin spots and confirm that masked areas are genuinely clean.
Afterwards, coated boards move into one of two dedicated SCH Technologies drying cabinets, both fitted with fume extraction. There, the boards cure under controlled conditions before moving on to final test.
| Equipment | Purpose |
| 1 x Nordson Asymtek SL940 (2021) | Primary automated coating machine, fitted with SC280, SC400 and DV05 heads |
| 1 x Nordson Asymtek C740 | Automated selective coating, run alongside the SL940 for additional capacity |
| HumiSeal 1B31S | Air-cured acrylic coating used on both machines: MIL-I-46058C, IPC-CC-830, RoHS compliant |
| 1 x SCH Technologies Spray Booth | Manual spray application for prototypes, low volumes and complex assemblies |
| 1 x SCH Technologies IB100 UVA Booth | Dedicated inspection of coated boards using UV fluorescence |
| 2 x SCH Technologies Drying Cabinets | Controlled curing with integrated fume extraction |
In practice, we coat boards every week for customers in the kind of sectors where uncoated electronics simply would not survive:
Of course, plenty of UK contract electronics manufacturers list conformal coating services on their capability pages. However, far fewer have the equipment, the qualified material and the inspection capability to back it up properly, and fewer still offer both manual and automated coating under the same roof.
In short, if you are evaluating partners for a project that needs reliable, well-documented coating, our full quality and certifications story is on the key quality page. Additionally, our certifications cover ISO 9001, ISO 13485 and JOSCAR, which matters in regulated sectors
Whether you need full production runs through our automated cell, careful manual coating of complex prototypes, or indeed a combination of both as you scale up, we are happy to talk it through. Firstly, send your drawings, bill of materials and any environmental specs you are working to. Then we will come back with a considered, properly costed response. In the meantime, feel free to contact us to start the conversation.
