SunSpot 2: Applications & adhesives, every question, answered

What kinds of adhesives can the SunSpot 2 cure?

It's built for rapid curing of photo-initiated adhesives, resins, coatings, inks and paints, single-component chemistries that polymerize on exposure to light.

The 200 W arc lamp covers a broad 275–650 nm spectrum, so most commercial light-cure formulations fall inside its output.

Does it cure UV acrylics?

Yes, UV acrylics are the mainstream spot-cure chemistry, and the SunSpot 2 delivers more than 18,000 mW/cm² of UVA at the light-guide tip, curing most acrylate formulations in seconds.

Check your adhesive datasheet for required wavelength and dose; the 275–650 nm output covers UVA-cure acrylates comfortably.

Will it work with cationic epoxies?

Yes. The arc's broad 275–650 nm output covers the photoinitiators used in free-radical acrylates and cationic epoxies alike.

Match the wavelengths on your adhesive datasheet against the lamp spectral charts in the manual to confirm the fit.

Can it cure visible-light-cure adhesives?

Yes, output extends through the visible range to 650 nm, so visible-cure and UV/visible dual-band adhesives are covered.

For chemistries that lean heavily on visible light, Uvitron also offers a visible-enhanced 200 W replacement lamp (UV4792).

My adhesive needs UVB. Can the SunSpot 2 deliver it?

Yes. The mercury arc produces UVB, and a UVB-enhanced replacement lamp (UV2170) is available for chemistries that need more of it.

The standard heat filter transmits 300–450 nm; for UVB-heavy work it can be removed, and a fiber light guide is recommended for long exposures without the filter.

How do I get rid of surface tack on coatings and inks?

Shorter UVB wavelengths (280–315 nm) carry more energy and are effective at removing surface tack on thin layers of coatings, inks and paints.

Remove the standard heat filter for those cases, and consider a fiber light guide, it isn't degraded by the short wavelengths the way liquid guides are.

Can it cure through thick adhesive layers?

Yes, deep curing relies on the longer UVA and visible wavelengths, which the SunSpot 2 produces in force. Encapsulation work typically cures well to around 5 mm of depth.

For deeper pots, fill and cure in two passes or specify a dual-cure (UV plus moisture or heat) chemistry.

Will it cure tinted or opaque adhesives?

Colored or more opaque adhesives attenuate UV, so they need the longer UVA and visible wavelengths, exactly where the SunSpot 2's spectrum is strong.

Fully opaque sections still block light entirely; anything the light can't reach needs a dual-cure chemistry or a different joint design.

What about adhesive in shadowed areas?

UV curing is line-of-sight, shadowed adhesive stays wet. Design fixtures so the guide tip sees every fillet, or angle two light-guide poles at opposing 45-degree positions to reach around vertical walls.

Where shadows are unavoidable, use a dual-cure adhesive with a secondary moisture or heat mechanism.

Can it cure through glass or clear plastic?

Sometimes, UV is easily attenuated by any material that isn't optically pure, and even window glass blocks most UV wavelengths. Longer UVA and visible light transmit best through substrates.

If you must cure through a substrate, favor an adhesive that responds to UVA/visible light and confirm results on your own first articles.

Is it good for wire tacking on PCBs?

Yes, that's a core application. Dispense small dots of a low-shrink UV acrylate over the wire and a 1–4 second timed exposure brings each dot to handling strength while the rest of the board stays at ambient.

Can I stake connectors with it?

Yes. A spot cure reinforces a connector shoulder at exactly one point, no oven pass, no masking, no thermal cycling of neighboring joints.

Typical staking exposures run 1–4 seconds with a 3–8 mm spot.

Does it suit coil and magnet-wire termination?

Yes, fine magnet wire on a transformer bobbin is a classic use. A dot of UV acrylate over the termination cures in seconds so the wire can't shift during depaneling, coating, or test.

Is spot curing safe on a populated board?

Yes, the energy goes only where the adhesive is, so neighboring components stay at ambient temperature. There's no reflow risk and no board warp from a bulk heat cycle.

The dichroic reflector and in-line heat filter also strip most infrared from the beam, keeping the output cool.

Can I use it for potting and encapsulation?

Yes, dam-and-fill encapsulation of sensors and dies is a strong fit. Dispense the dam, gel it with a short exposure, fill, then cure; the broad 275–650 nm spectrum drives cure deep into the fill.

One lamp can split across up to four light-guide poles, so a full dam-and-fill perimeter cures in a single timed exposure.

Is it used for medical device bonding?

Yes, needle bonding, catheter assembly, and similar joints benefit from its timed shutter and lamp power regulated to plus or minus 1 percent, which keep dose repeatable part after part.

Pair it with a radiometer to verify dose against your validated window on a routine schedule.

Can it bond lenses and optical components?

Yes, lens fixing is a standard spot-curing job. The filtered arc output carries very little infrared, so the joint doesn't heat and shift alignment while it cures.

Does it handle fiber-optic termination?

Yes, fiber termination is one of the medical/photonics applications we supply for regularly. A small 2–5 mm spot and a short timed exposure fix the ferrule with a controlled, repeatable dose.

Can it cure UV coatings, inks, and paints?

Yes, the manual lists coatings, inks and paints alongside adhesives and resins as intended materials.

Thin coatings and inks that need UVB to reach a tack-free surface are a particular strength of the arc source.

What working distance should I use?

Hold the light-guide tip roughly 0.5 to 3 inches from the surface being cured, depending on the spot size and intensity you need. Closer means a smaller, hotter spot.

Avoid touching the tip to uncured adhesive, it will cure onto the quartz window and cut light output.

How intense is the output at the tip?

Typically more than 18,000 mW/cm² of UVA (320–390 nm) at the end of the light guide when the lamp is new, about 18 W/cm² measured at 1 inch.

That's among the highest output of any benchtop spot source, which is what makes 1–10 second cures routine.

How fast are typical cures?

Most photo-initiated chemistries reach cure in one to ten seconds at the SunSpot 2's intensity, tacking jobs often run 1–4 seconds, structural bonds and encapsulation 2–10 seconds per zone.

How do I estimate cure time for my adhesive?

Use the rule from the manual: curing time in seconds equals required light energy (J/cm²) divided by delivered intensity (W/cm²).

The relationship isn't perfectly linear for every chemistry, high peak intensity for a short time often outperforms the same dose spread over a longer exposure.

Where do I find the dose my adhesive needs?

On the adhesive manufacturer's datasheet, they typically specify either the energy required for cure or a required intensity and time at given wavelengths.

Different products have different reactivity, so plan to fine-tune exposure on your own first articles.

My adhesive cures slowly. What should I check?

Check the basics first: guide tip within 0.5–3 inches of the work, intensity setting turned up, and the adhesive's spectral needs matched to the installed lamp and filter.

Also inspect for a dirty or damaged guide, reflector or filter, and consider lamp age, output falls to about half of initial by 2,000 hours.

Why is the cured surface still tacky?

Surface tack usually means the topmost layer needs shorter, higher-energy wavelengths. The SunSpot 2's UVB content handles this, remove the 300–450 nm heat filter if the tack persists.

A UVB-enhanced lamp (UV2170) and short-wavelength-tolerant fiber guides are available for tack-critical coating and ink work.

Can I cure more than one point at a time?

Yes, multi-pole light guides split the single 200 W lamp into two, three, or four output legs that cure simultaneously without compromising speed.

That's how a four-point bond line or multi-joint fixture cures in one timed exposure from one system.

How do I cure a bead or perimeter bond line?

Position multiple light-guide poles along the bond line so their spots cover the full bead, then cure in a single exposure, or index the part under a single spot in steps.

Remember spots grow with distance: about 1.5 inches across at 1.5 inches away, 3 inches at 3 inches.

Is it suitable for heat-sensitive substrates?

Yes. The lamp's dichroic reflector plus the in-line heat filter remove nearly all of the unusable heat energy from the beam, which is exactly why the manual calls it ideal for fast curing on heat-sensitive substrates.

Will the beam overheat my parts?

The optical filtering keeps curing output cool, but at very close range with the shutter open the tip can still deliver significant heat, so keep the shutter closed between cures and never park the tip against a heat-sensitive or flammable surface.

What should I cure parts on?

Always cure on a metallic or non-flammable surface. The manual warns against placing the light-guide output on or near anything flammable or heat-sensitive while the shutter is open or the tip is still hot.

What does the 300–450 nm heat filter do?

The installed UV2554 filter passes the useful 300–450 nm curing band while attenuating heat-producing energy, and it extends liquid light-guide life by blocking wavelengths below 300 nm.

Remove it only for thin coatings and inks that need UVB to kill surface tack, most adhesives cure fine with it in place.

Are different lamp types available?

Yes, three 200 W quick-change modules: the standard UVA-enhanced lamp (UV1866, installed), a UVB-enhanced lamp (UV2170), and a visible-enhanced lamp (UV4792).

Each is optimized for a different part of the spectrum so the system adapts to your chemistry instead of the other way around.

Do you have light guides for deep-UV work?

Yes, deep-UV liquid light guides (UV3381 at 1 m, UV1508 at 1.5 m, 5 mm diameter) are listed for short-wavelength applications, alongside fiber guides that tolerate UVB.

Does it work with dual-cure adhesives?

Yes, the broad-spectrum arc handles the light-cure portion of dual-cure (UV plus moisture or heat) chemistries, which are the right answer for shadowed geometry and pots deeper than about 5 mm.

What wavelength range does it cover?

Radiation flux spans 275–650 nm, from the top of UVC through UVB, UVA and well into visible light.

That breadth is the SunSpot 2's defining advantage over single-wavelength LED sources.

What are UVA, UVB and UVC exactly?

Per the manual's spectrum chart: UVC is 200–280 nm, UVB is 280–315 nm, UVA is 315–400 nm, and visible light begins at violet around 400–440 nm.

Longer UVA/visible wavelengths penetrate deep; shorter UVB/UVC carry more energy and excel at surface cure.

Does peak intensity matter more than total dose?

Often, yes. Curing speed isn't linear with intensity for many adhesives, the fastest, most complete reaction frequently comes from high peak intensity over a short time rather than the same (or even higher) dose spread out longer.

Can I turn the intensity down for sensitive materials?

Yes, three ways: the lockable front-panel knob (60–100 percent of lamp power), light-guide insertion depth in the receptacle (thumbscrew-lockable), and tip-to-part distance.

Combined, the knob and guide depth give a 25–100 percent output range.

How do I get a bigger or smaller spot?

Move the guide tip: the spot grows with distance and shrinks (and intensifies) as you close in, over a working range of roughly 0.5 to 3 inches.

You can also step up from the standard 5 mm guide to an 8 mm diameter guide for wider coverage.

What light-guide sizes are offered?

Liquid-filled guides come in 5 mm and 8 mm diameters at 1, 1.5, 2 and (for 8 mm) 3 m lengths; fiber guides come in matching sizes. The standard included guide is the 1 m x 5 mm UV0570.

Liquid or fiber light guide, which should I pick?

Liquid guides are the economical standard and transmit UVA extremely well; fiber guides are long-life, tolerate UVB and short wavelengths, and suit long exposures with the heat filter removed.

Liquid guides typically last one to two years in normal use; minimizing UV exposure time and avoiding bending extends their life.

Which radiometer should I use to verify dose?

The UV0567 Spot Cure radiometer reads 0.2–19.99 W/cm² over 320–390 nm and is the standard match for the SunSpot 2. The Power Puck II (UV1451-H) adds four bandwidths, UVA, UVB, UVC and visible.

A holding fixture with a 10 mm collet (UV4244-10) positions the guide tip repeatably over the puck.

How often should I check output with a radiometer?

Put it on a fixed schedule, weekly spot-checks are a good production habit, and log the readings. A 20 percent drop from your baseline means it's time to service the guide or swap the lamp.

Record initial lamp intensity and hour-meter readings when new, so later readings have a reference.

Typical parameters for PCB tacking?

From our application note: 1–3 mm adhesive dots, a 3–8 mm spot, and 1–4 second exposures. Fixture the guide tip 8–12 mm above the joint for a 5 mm spot.

Typical parameters for bonding and potting?

Broad 275–650 nm output, 5–12 mm spots, 2–10 seconds per zone, up to four zones per lamp with a multi-pole guide, and reliable depth of cure to about 5 mm.

Typical parameters for medical assembly?

Fine 2–5 mm spots and 1–5 second exposures are the norm for needle bonding, catheter joints, lens fixing, and fiber termination, always verified against a validated dose window with a radiometer.

Is it for lab use or production?

Either, the manual describes it as a benchtop or machine-mounted source suitable for laboratory use and for volume production applications.

Many customers qualify a process at the lab bench and then bolt the same unit into a production fixture.

How should I prep surfaces for structural bonds?

Solvent-wipe each substrate, and abrade or plasma-treat low-surface-energy plastics for reliable adhesion before dispensing.

Prep quality shows up directly in shear-test results on your first articles.

Any tricks for inspecting cured bonds?

Specify an adhesive with a fluorescing agent, coverage checks become a two-second look under a UV lamp, and 100 percent visual inspection becomes practical.

Will curing stress fine-pitch pads or joints?

Choose a low-shrinkage acrylate rated for tacking and staking, high-shrink chemistries can lift fine-pitch pads or stress solder joints as they cure. The light source itself adds no bulk heat.

Can I encapsulate a sensor without cooking it?

Yes, that's the point of dam-and-fill with a spot source: the filtered beam carries little heat, and the broad spectrum cures the fill through its depth in a 2–10 second exposure instead of an oven cycle.

My resin cures in sunlight. Will this cure it?

Almost certainly, sunlight's curing power comes from its UV and visible content, and the SunSpot 2 concentrates that same 275–650 nm band into an intense, regulated spot.

You get seconds instead of minutes, plus a timer and regulated lamp power for repeatable results in any weather.

Why use light-cure instead of two-part epoxy?

Light-curing resins are single-component: no measuring, no mixing, no pot life to race. They stay liquid until you expose them, then cure on demand in seconds.

Why do cure times differ between adhesive brands?

Adhesives, inks and coatings from different manufacturers have different reactivity levels, so exposure must be adjusted per product. Consult the manufacturer's datasheet for recommended times, then fine-tune on your own parts.

Adhesive cured onto the guide tip, now what?

Wipe the quartz tip with a soft cloth dampened with isopropyl alcohol; for stubborn cured deposits the manual allows a careful light scrape with a razor as a last resort.

Prevent it next time by keeping the tip off uncured adhesive, cured buildup on the window cuts light output.

Can it cure inks on thin, heat-sensitive films?

Yes, the dichroic reflector and heat filter strip most heat from the beam, and the arc's UVB content is what thin ink and coating layers often need for a tack-free surface.

For UVB-heavy work, run without the heat filter and use a fiber light guide.

Where can I read your application guides?

Our Applications page has three field-proven process notes, PCB and component tacking, adhesive bonding and potting, and medical/optical assembly, each with process steps, working parameters, and a recommended setup.