2835 LED Sourcing Guide (2025): What It Means, Real Watts, Dimming Rules, SMD Basics & 2835 vs 5050

2835 LED Sourcing Guide 2025: Meaning, Wattage, Dimming & 2835 vs 5050

For U.S. wholesale buyers in New York: decode 2835 LEDs—what it means, real wattage, dimming without flicker, SMD assembly tips, and when to choose 2835 vs 5050. RFQ lines included.

Most “SMD 2835 high-efficiency” pages leave out the numbers that matter—actual watts, safe dimming, and when 2835 beats 5050.Guess wrong and you’ll fight flicker, tint mismatch, and hot strips—plus RMAs that erase your margin and reputation.Use this sourcing guide: five buyer-grade answers, RFQ sentences you can paste, and quick checks to verify before any PO.

Lock 2835 as a size code, do I×Vf watt math, demand flicker metrics, control reflow voids, and compare by $/kilolumen landed—not brochure hype.

If you’re buying for New York distribution, your search history probably reads: “What does 2835 LED mean?”, “How many watts is a 2835?”, “Is 2835 dimmable?”, “What does SMD mean?”, and “Which is brighter, 2835 or 5050?” Get those five right and your installs run quiet; get them wrong and you’re scheduling late-night service calls and processing returns.

Start with geometry. 2835 is a package footprint—2.8 × 3.5 mm—that houses a mid-power InGaN die with an exposed thermal pad. The shape itself enables tight LED pitch, smooth diffusion, and a direct heat path into copper. Today’s Ra80 bins deliver strong lm/W at modest current; Ra90 options trade a little efficacy for higher R9, which makes textiles, food, and skin tones look right.

Then power. Watts aren’t printed on the package—they’re current × forward voltage (I×Vf). Push current without upgrading thermals and a “0.2 W” catalog part operates like 0.36–0.5 W, spiking junction temperature (Tj), accelerating lumen loss, and shifting color.

Dimming is not “yes/no.” To avoid eye strain and camera banding, drivers should meet IEEE 1789 guidance with Percent Flicker and Flicker Index documented, plus PWM ≥ 2–4 kHz or CCR. Phosphor chemistry matters too: fast-decay mixes track PWM more cleanly at low duty.

“SMD” means surface-mount device: reflow assembly that reduces labor and improves thermals—if your stencil, paste, and profile keep under-slug voids low. Otherwise, your warranty clock starts ticking.

Finally, brightness economics. Per package, 5050 hits harder and still rules RGB. On dense white strips normalized to $/kilolumen landed (unit + freight + duty + bin premiums), 2835 frequently wins with calmer thermals and smoother diffusion.

Below, each section follows PAS and includes a short , a 200+ word buyer snippet, an image placeholder, an in-depth paragraph (≥200 words), and paste-ready RFQ lines. As XGM (Shenzhen Xinguanming)—14 years in LED R&D, 3,000+ customers—we back claims with native LM-80/TM-21, EN 62471, and RoHS/REACH PDFs.

1·Think “Footprint,” Not “Brightness”: What 2835 Really Is

“2835” = 2.8 × 3.5 mm mid-power SMD with an exposed thermal pad—tight pitch and stable heat flow.

Teams buy “2835” as if it’s a luminous grade and swap reels freely.That’s how zebra tint, hot spots, and SMT rework chew through schedules and profit.Treat 2835 as geometry. Inside is a single InGaN die on a reflective leadframe, coated with phosphor, and bonded to an exposed slug that dumps heat into copper. On 8–12 mm PCBs at ≈120 LED/m, this format delivers uniform output with manageable Tj. In 2025 production, Ra80 whites are highly efficient at ~65 mA; Ra90 boosts R9 for retail and medical-beauty. Control appearance with ≤3 SDCM in general spaces and ≤2 SDCM in camera-sensitive installs. Insist on native (not screenshots) LM-80/TM-21 reports and EN 62471 safety docs to survive corporate due diligence. Quick primer: package overview · SDCM explainer

Specs to lock in drawings/RFQs:

Thermal: target RθJC ≤ 12 °C/W; micro-vias under the slug; 2-oz copper on FR-4 for ~0.2–0.24 W; step to MCPCB for ≥0.30–0.36 W designs. Guide: pad & via card

Materials: silver-mirror leadframes lift lm/W but risk sulfur tarnish near leather/rubber—spec anti-sulfur encapsulant. Policy: anti-sulfur checklist

Color policy: ship ≤2 adjacent bins; reel cert lists CCT, Duv, Ra, R9, lm, Vf, lot. Template: bin map + certificate

SMT hygiene: share pad & stencil files; lock cathode orientation across EMS lines. Drawing: 2835 pad/stencil

RFQ line (paste-ready):“2835 package 2.8×3.5 mm; exposed pad; RθJC ≤ 12 °C/W; ≤3 SDCM (≤2 optional); anti-sulfur encapsulant; provide native LM-80/TM-21 & EN 62471 PDFs.”

2·How Many Watts Is a 2835 LED? Do I×Vf—then verify Tj

Wattage = current × forward voltage; lifetime depends on junction temperature, not catalog slogans.

A “0.2 W 2835” gets driven like 0.36–0.5 W without changing the board.Junction temperature climbs, L70 shrinks, whites drift green/pink, and warranty claims follow.Compute Pd = I × Vf from your driver current and the supplier’s Vf histogram. Typical: 65 mA × ~2.9 V ≈ 0.19 W (FR-4 OK). Push to 120 mA × ~3.0 V ≈ 0.36 W—safe only with MCPCB or heavy copper. Estimate ΔT = Pd × RθJC and add board-to-ambient to get Tj; aim Tj ≤ ~105 °C. If you need more lumens, under-drive and add emitters; eight 2835s at 65 mA spread heat, raise lm/W, and reduce hot spots versus over-driving a few. Keep driver ripple < 5 %—peaks, not averages, stress LEDs. Tools: power/thermal sheet · ripple explainer

Controls to stop surprises:

Vf distribution: spec typ 2.8–2.9 V; max 3.1 V @ 65 mA and request the histogram, not just min/max. How-to: reading Vf plots

String strategy: series preferred; if paralleling, add balancing resistors or matched copper to avoid current hogging. Note: parallel best-practices

Driver topology: constant-current buck with spread-spectrum PWM to reduce EMI and peaking. Brief: driver checklist

Thermal step-up: beyond ~0.30–0.36 W per LED, migrate to MCPCB and verify Tc with thermocouples. SOP: thermal check card

RFQ line (paste-ready):“Quote lm/W at 65 mA and our max current; include Vf histogram, RθJC data, ΔVf after 1,000 h @ 85 °C/IFnom, and derating curve.”

3·Is 2835 Dimmable? Yes—if you respect flicker physics

Use 2–4 kHz PWM or CCR, verify IEEE 1789 metrics, and cap low-level color shift.

Constant-voltage strips on triac wall dimmers cause ripple and camera banding.Guests see strobe, staff report headaches, reviews mention “flicker,” and brand trust drops.Pair 2835 with drivers that publish Percent Flicker and Flicker Index (IEEE-1789 aligned). Put numbers in writing: Percent Flicker < 10 % and Flicker Index < 0.05 at 100 % output. Then test at 20 %—the danger zone for cheap drivers. Ask for phosphor decay curves; fast-decay mixes track PWM better, while slow-decay can mask strobe but warms CCT at low duty. Limit Δu′v′ ≤ 0.003 from 100 % → 10 % at Tc 25/55 °C so whites don’t wander. Reference pack: flicker cheat-sheet · low-duty test SOP

What to hand your engineer:

Driver mode: PWM ≥ 2 kHz (4 kHz ideal) or CCR; add a shunt FET to stop ghosting <2 % duty. Checklist: dimmer compatibility

EMI & peaking: spread-spectrum modulation reduces RF noise; keep LED-to-driver traces short and grounds tight. Tip card: layout quick wins

Proof: scope screenshots at 100 % and 20 % on your load with metrics; add Pst_LM/SVM if the spec demands it. Template: flicker report pack

Color stability: confirm CCT and Δu′v′ vs dim level for your Ra80/Ra90 recipe. Plan: Δu′v′ test method

RFQ line (paste-ready):“Provide IEEE-1789 flicker metrics and Δu′v′ vs dim level on our driver; attach scope screenshots at 100 % and 20 % output.”

4·What Does SMD Change? Assembly & heat—not hype

SMD = reflow quality. Stencil, paste, and profile decide voids—and voids decide lifetime.

“One stencil fits all” creates under-slug voids and tombstoning on 2835 pads.Voids raise RθJA, shorten life, and murder yield; missed go-lives cost more than any paste upgrade.For 2835, use 0.12–0.15 mm stencils and type-4/4.5 paste; ramp < 3 °C/s; peak 245 ± 5 °C (nitrogen preferred). X-ray first articles and adjust apertures/soak if voids exceed ~30 % under the thermal pad. Prefer no-clean flux to avoid moisture pockets under lenses; bake PCBs stored > 6 months. Share a one-page reflow card before the pilot build so nobody “guesses” your process. Cards: SMT setup checklist · void-control guide

On-floor controls that pay back:

Area ratio ≥ 0.66 for paste transfer; consider step stencil on the thermal pad. How-to: aperture tuning tips

Paste bricks aligned to copper fill to limit float/skew; avoid lens shadowing. Playbook: stencil & pad card

Sampling & rejection: follow IPC-7093 X-ray sampling; reject lots with repeat void hot-spots; tweak soak/peak dwell. Grid: X-ray acceptance matrix

Cleaning policy: avoid water-soluble flux under lenses; if used, validate wash + bake cycles and re-check Δu′v′. SOP: post-wash color check

RFQ line (paste-ready):“Provide pad layout, stencil guidance, max under-slug void %, and recommended reflow curve for the quoted 2835; confirm IPC-7093 compliance.”

5·Which Is Brighter—2835 or 5050? Choose by use case and $/klm landed · PAS

Per package, 5050 is brighter; per $/kilolumen landed on dense white strips, 2835 usually wins. RGB? 5050 rules.

Teams compare single-package lumens and ignore strip density, driver channels, and heat load.You overbuy 5050s, drivers run hot, diffuser hotspots appear, and BOMs balloon.Normalize quotes to $/klm landed (unit + freight + duty + bin premiums). A white 5050 (often multi-die) out-punches a 0.2 W 2835 per package, so it’s ideal for RGB and punchy modules. But eight 2835s at ~65 mA spread heat, keep lm/W high, and often beat three 5050s on $/klm once driver channels and logistics are counted. For outdoor “punch,” derate 5050 current ~20 % and add surge protection. Tools: $/klm calculator · use-case matrix

Decision matrix to paste into team notes:

Retail/task/appliance → 2835 white, ≤3 SDCM (≤2 premium), Ra80/Ra90 per channel; bin policy template

Stage/architectural RGB → 5050 (addressable or non-addressable); PWM & EMI demands raise BOM; RGB driver notes

Outdoor signage → 5050 white + thermal derating + strong surge design; surge & derate card

Supply risk → 2835 whites are widely second-sourced; addressable 5050s may bind you to one IC vendor; dual-source plan

RFQ line (paste-ready):“Quote 2835 white (Ra80 & Ra90) and 5050 white/RGB as $/pc and $/klm landed (FOB & DDP New York). Include SDCM, RθJC, IEEE-1789 metrics, surge limits, and lead time.”

Binning: ≤3 SDCM (≤2 premium); shipment ≤2 adjacent bins; reel cert lists CCT, Duv, Ra, R9, lm, Vf, lot.

Thermal & Reliability: RθJC ≤ 12 °C/W; HTOL 1,000 h @ 105–125 °C, 85/85 1,000 h, –40↔125 °C 1,000 cycles, surge 10/700 µs to 2 kV; lumen loss ≤ 10 %, ΔVf ≤ 0.1 V, Δu′v′ ≤ 0.006.

Dimming: Provide IEEE 1789 metrics; Percent Flicker < 10 %, Flicker Index < 0.05 at 100 %; verify again at 20 %.

Compliance: LM-80/TM-21, EN 62471, RoHS/REACH—native PDFs.

Pricing: Quote $/pc and $/klm landed (FOB Shenzhen & DDP New York); itemize bin premiums; include NET-30/NET-60.