COB vs SMD LED Strips

Two ways to put light on a ribbon

SMD construction (surface-mounted device) solders individual packaged LEDs onto the flexible board at intervals — the classic dotted ribbon, in densities from 30 to 240 diodes per meter. COB construction (chip-on-board) bonds hundreds of tiny bare chips directly to the board and floods the whole channel with phosphor, producing one continuous emitting line with no visible dots at any distance.

Neither is 'newer is better': COB is the newer packaging, but both families are mature, and the right choice is application-shaped rather than generational.

The optical difference is the visible one

SMD's dots disappear only behind diffusion — an opal channel lid, a cove's bounce, or distance. Anywhere the strip itself is visible, or reflects in gloss surfaces (kitchen counters under cabinets are the classic tell), SMD shows a row of points and COB shows a clean line. That makes COB the default for exposed installs, shallow channels where diffuser distance is scarce, and mirror-adjacent lighting.

SMD retains an optical advantage of its own at the high end: single large diodes take secondary optics well, which is why aimed and lensed products stay SMD, and the discrete-diode format is also where addressable per-pixel control lives — a COB strip can be addressable only in coarser zones, since its chips share phosphor in a channel.

Heat, density and honest wattage

Density claims mislead in both families. High chip counts do not make a strip more efficient — watts per meter and the quality of the board's copper decide output and temperature. COB spreads its heat continuously along the channel, avoiding SMD's per-diode hot spots, but a high-wattage COB strip still needs the same aluminum-channel heat-sinking any dense SMD strip does. The rule survives packaging fashions: past roughly 10 W per meter, plan mounting on metal, whatever the chips look like.

Repair and modification favor the dotted family

SMD's discrete construction is friendlier to everything this site's repair guides do: individual dead diodes can be identified and replaced, cut points come frequently, and solder pads are conventional. COB strips cut and splice at marked intervals too, but a failure inside the phosphor channel is not bead-replaceable — the repair unit is the segment, and its continuous face makes even diagnosing a single dark chip meaningless. Projects that anticipate modification, extension and repair over the years lean SMD; sealed decorative installs that will live and die as installed lean COB.

Choosing in practice

• Strip visible or reflected: COB, for the dot-free line
• Behind a diffuser or in a cove: either — buy on CRI, wattage and price, not packaging
• Per-pixel addressable effects: SMD families (WS/SK types) — that is where the pixels are
• Repairable, extendable, spliceable installs: SMD's granularity wins
• Shallow channels with no diffusion distance: COB solves what optics cannot

Buying signals in both families

Whichever construction you choose, the specification lines that predict satisfaction are the same. Watts per meter tells you the real output class and the heat-sinking obligation; CRI at 90 or above matters wherever the light falls on food, faces or wood; and stated voltage tolerance hints at driver quality. A listing leading with chip counts and 'super bright' while omitting watts per meter is describing marketing, not product.

One COB-specific check is worth adding: ask about the phosphor channel's uniformity across reels. Because COB's emitting surface is continuous, batch-to-batch color variation shows as a visible seam where two reels meet in one sightline — buy a single reel long enough for each continuous run, or accept a break in the line where reels join.

Where these strips are actually installed

The families sort neatly across the rooms this site covers. Under-cabinet kitchen runs are COB's showcase: the strip reflects in a gloss worktop, diffusion distance is minimal, and dots would be visible in every glance downward. Cove and ceiling perimeter lighting bounces off plaster before anyone sees it, so SMD's economy wins unless the cove is shallow. Stair and corridor accents at eye level favor COB; wardrobe interiors and drawer lighting favor whichever is cheaper, since the source is hidden by design.

Media walls and desk backdrops are the interesting case, because they are usually addressable — which decides the family before optics get a vote. There, the honest sequence is to choose the pixel format first, accept its dotted construction, and recover the smooth look with a deep diffuser channel rather than wishing for a COB that could not have done the effect anyway.

Put this to work

Whichever family you choose, the supporting decisions are the same, and these guides carry them:

• Power supply sizing for any strip family
• Soldering strip joints: pads, tinning and strain relief
• Replacing a single dead LED on a board (SMD's repair privilege)