Through-Hole vs SMD LED: What's the Difference? Read This Before You Choose
1. Appearance: One Has "Long Legs", the Other Is "Flat"
Through-hole LEDs, also called plug-in LEDs in the industry, are most classically the 3mm (F3) and 5mm (F5) round-head lamps: an epoxy resin body with two long metal leads underneath. During soldering, the leads go through the PCB holes and are soldered on the back side of the board — hence the name "through-hole".
SMD LEDs are flat little blocks without long leads; the bottom pads are soldered directly onto the PCB surface. Common codes like 0603, 0805 and 1206 are size designations — take 0603: the body is about 1.6×0.8mm, barely bigger than a sesame seed.
Besides round heads, through-hole LEDs also come in straw-hat, flat-top and concave shapes; the difference is mainly the lens shape on top of the epoxy body, which directly affects whether the beam is focused or diffused. SMD packages offer plenty of variants too: besides the most common single-color chips, there are bi-color, tri-color RGB and side-emitting structures. When selecting, decide the package first, then the color — the thinking becomes much clearer.
So by appearance alone, the two are easy to tell apart. But the real differences go beyond looks — read on.
2. Through-Hole vs SMD LED: Comparison Table
| Item | Through-Hole LED (5mm example) | SMD LED (0805 example) |
|---|---|---|
| Dimensions | 5mm body diameter, ~8.6mm total height | 2.0×1.25mm, ~0.8mm thick |
| Lead Form | Two long leads, through-hole soldering | Bottom pads, surface mount |
| Typical Operating Current | 20mA | 20mA |
| Viewing Angle | 15°-60°, mostly focused-beam types | Around 120°, mostly diffused types |
| Soldering Process | Wave soldering or hand soldering | Reflow soldering, suits high-volume SMT lines |
| Repair & Replacement | A soldering iron is enough | Usually requires a hot-air gun |
The table shows their operating current is actually similar; the differences concentrate in size, viewing angle and process. Through-hole LEDs are larger with a built-in lens in the epoxy body, giving a focused beam — good where status must be seen from a distance. SMD LEDs are thin and small with a wide angle — good for hiding inside tight structures with light pipes for even diffusion.
3. Different Production Processes, Different Cost Structures
Through-hole LEDs run on insertion lines: manual insertion or auto-insertion machines, then wave soldering. Line investment is low, and small-batch, multi-variety switching is flexible; the downside is large board area and high labor share in insertion and soldering.
SMD LEDs run on SMT lines: tape-and-reel feeding, high-speed pick-and-place, one-pass reflow soldering — hundreds to thousands of pieces per minute, and the bigger the volume, the lower the unit cost. SMD also needs no drilled holes, freeing up the back side of the PCB.
Through-hole LEDs can also get secondary processing like lead cutting, 90° bent-lead forming, or built-in current-limiting resistors in a sleeve — most special mounting needs can be solved.
The industry has a rough rule: consumer electronics have basically all moved to SMD, such as 0603 SMD LEDs and 0805; while industrial control equipment, instruments and home-appliance panels still keep plenty of through-hole parts, such as F3 through-hole LEDs (3mm indicators), because these products may not ship huge volumes but demand high visibility and reliability from their indicators.
4. How to Choose? Three Practical Tips
1. Look at structural space. Tight board space or limited enclosure thickness — routers, power banks, Bluetooth earphones — go straight for 0603 or 0805 SMD. For panel-hole mounting where the lamp should protrude, choose 3mm or 5mm through-hole.
2. Look at production volume. For monthly usage above several hundred thousand pieces, SMD with an SMT line has lower overall cost; for small batches of thousands to tens of thousands, through-hole manual or semi-automatic lines are more flexible and switch models faster.
3. Look at indication distance. If operators must read equipment status from one or two meters away, choose a focused through-hole LED, or a high-brightness SMD with a light pipe; for simple on-board status, a regular SMD is enough — 1206 SMD LEDs are common on all kinds of industrial control boards, for example.
If unsure, send your product structure drawing and usage environment to the LED manufacturer and let their engineers verify the parameters — much faster than digging through datasheets on your own.
About Hongcheng Optoelectronics
Hongcheng Optoelectronics (Dongguan Hongcheng Optoelectronics Co., Ltd.) has 20+ years of LED packaging experience. Products use Grade-A chips and 99.9% pure gold wire bonding, are RoHS certified, and support customization, samples and volume quotes. Tel/WeChat: 139 2571 4318, Email: sales@led-hc.com.
