Most UV curing LED specifications start with wavelength and intensity and only later ask how the light will physically reach the adhesive — and that ordering is backwards. A 7,500 mW/cm² spot lamp cannot cure a 12-inch gasket bead in one shot, and a 12-inch flood lamp cannot avoid irradiating the UV-sensitive sensor sitting 3 mm from a hairline bond. Form factor is the first decision, because it determines which intensity figures are even relevant.
Q: What is a UV curing LED, and how does it differ from a mercury lamp?
A: A UV curing LED is a solid-state source emitting a narrow band — 365, 385, 395, or 405 nm — that triggers photoinitiators in adhesives, coatings, and resins. Against mercury-arc lamps it offers instant on/off, no warm-up, no mercury, far lower infrared heat on the part, and 15,000–20,000-hour rated life. Its limits: no UVB/UVC output (some cationic and surface-cure chemistries still favor arc lamps), and line-of-sight delivery, so shadowed 3D geometry needs the right head shape — which is the subject of this guide.
Why Geometry Comes Before Wavelength
Every UV curing LED system in Incure’s line is available at 365, 385, 395, or 405 nm and factory-configured to a single wavelength, so the wavelength decision is the same across form factors — it follows the adhesive’s photoinitiator absorption peak, and it is settled before the order is placed. What differs between form factors is the shape of the cure zone, the working distance the intensity was measured at, how the intensity falls off away from that distance, and whether the head can be enclosed, moved, or fixed. Those four properties decide whether a bond line gets the dose it needs, and no wavelength choice compensates for a mismatch in any of them.
The practical method is to draw the bond line first: its length, its width, how far the lamp face or lightguide tip can physically get from it inside the fixture, and what sits next to it that must not be exposed. That sketch points to a form factor before any spec sheet is opened.
Spot: Millimeter-Scale Bond Points, Steep Distance Falloff
A spot system delivers light through a lightguide to a small circular zone — on Incure’s L9000™ spot lamp, a 3 mm to 12 mm spot across a 9–30 mm focal range. Its defining property is intensity that is very high at the focal point and falls off steeply beyond it: 7,500 mW/cm² at 9 mm, 5,000 mW/cm² at 10 mm, 1,200 mW/cm² at 20 mm, and 223 mW/cm² at 30 mm at 365 nm. That falloff is the reason a spot system fits fiber-ferrule bonding, lens tacking, wire-tack points, and individual SMD or connector bonds — the cure zone is tiny, the fixture can hold the guide at a fixed few millimeters, and the surrounding assembly stays dark. It is the wrong choice whenever the fixture cannot guarantee working distance to within a millimeter or two, or the bond is longer than the spot.
The L9000™ runs up to four lightguides from one controller, so “several small points on one part” is still a spot problem, not a reason to step up to flood.
Focused Beam: Linear Bond Lines on Crowded Assemblies
When the bond is a line rather than a point — a gasket bead, a seam, a row of dispensed dots — a rectangular beam sized to that line delivers full intensity along its length without flooding the neighboring area. Incure’s M-Series™ focused-beam systems cover 5″×1″ (M51) up to 15″×2″ (M152), with M51 reaching 6,150 mW/cm² at 365 nm at the 2-inch recommended working distance. The 1-inch-wide models suit true linear beads; the 2-inch models add lateral tolerance for multi-row dispensing patterns. The M-Series™ is deliberately not chamber-compatible — it is built as an open-fixture head with direct optical access to the part, which is exactly what a linear bond on an in-process fixture requires.
Flood: Area Coverage Where Uniformity Outranks Peak Intensity
A flood array trades peak intensity for uniform coverage across a square field. Incure’s L-Series™ flood lamps run from L11 (1″×1″, 4,300 mW/cm²) through L44 (4″×4″, 3,100 mW/cm²) and L1212 (12″×12″, 1,900 mW/cm²) up to L1414 (14″×14″, 950 mW/cm²), all at a 2-inch working distance — intensity falls as area grows because the same class of array is spreading its output over more square inches. Flood fits conformal coatings, encapsulants, dome coatings, and any bond pattern scattered across a panel where the goal is that every point receives a consistent dose rather than that one point receives a high one. Flood lamps are also the only LED form factor Incure pairs with an enclosed cure chamber (C131C/C131D/C141C for L11–L44, C191C for L88–L1414), which matters when operator UV exposure or fixed curing distance is part of the specification.
Email Us with a sketch of your bond line — length, width, working clearance, and what sits beside it — and Incure’s engineers can identify the form factor before the wavelength and intensity discussion starts.
Water-Cooled Area: Flood Coverage at Spot-Class Intensity
The gap between flood and spot intensity is a cooling limit, not a fixed law. Incure’s water-cooled W44 delivers 8,100 mW/cm² across a 4″×4″ field — more than 2.5 times the air-cooled L44 over the same area — and W1212 reaches 3,100 mW/cm² across 12″×12″. Specify this form factor when the bond pattern needs flood-style coverage but the adhesive’s required dose, a pigmented or thick section, or a continuous duty cycle pushes past what an air-cooled array sustains. The trade-off is facility plumbing, covered in Incure’s water-cooled UV-LED specification guide.
Inline: The Form Factor Is Chosen, Then Mounted Over a Belt
A conveyor is not a fifth form factor — it is a way of moving parts under one of the four above. Incure’s CDM™ conveyor accepts L64/L88 flood heads and M51/M62 focused-beam heads, so the geometry decision is made exactly as it would be for a bench station, then the line speed is set so each point on the part receives the required dose as it passes. Dynamic uniformity figures (0.88 at 2 inches on the flood and focused-beam lines) apply here rather than static ones, since the part is moving during exposure.
A Four-Line Decision Checklist
- Cure zone shape: point → spot; line → focused beam; area → flood or water-cooled area.
- Working-distance control: if the fixture cannot hold ±1 mm, avoid spot; flood and beam heads are specified at 1–3 inches with gentler falloff.
- Adjacent sensitivity: UV- or heat-sensitive components within a few millimeters of the bond rule out flood in favor of spot or beam.
- Duty cycle and dose: continuous operation at high dose over an area points to water cooling; intermittent bench work does not.
Get those four answers on paper and the wavelength, intensity, and chamber questions each have a short list of candidates instead of the whole catalog.
Contact Our Team to walk through your bond-line geometry against Incure’s spot, focused-beam, flood, and water-cooled UV curing LED lines.
Visit www.incurelab.com for more information.