Shortwave or Medium-Wave? Picking the Right IR Lamp for Your SMT Line
When you’re setting up SMT soldering, the choice between shortwave and medium-wave IR lamps basically comes down to one thing: how fast you need those boards to hit reflow temperature. Both types use quartz glass. Why? Because it doesn’t freak out when the temperature spikes and it lets the heat pass right through without soaking it up.
Let’s talk about the physics (the simple version)
Shortwave IR is like a power hitter. It hits the board with high energy and sinks deep into the PCB and the components. It’s fast. Really fast. If you’re pushing a high-volume line and every second you shave off your cycle time equals more money, shortwave is your best bet. Medium-wave is a different story. It’s more of a gentle touch. It heats from the surface down, which takes a bit longer, but it’s way more controlled. It helps prevent those tiny surface components from frying before the solder paste underneath actually melts.
The reality of working with quartz
We use quartz because it won’t warp when things get scorching. But here’s the catch: it’s brittle. I’ve seen it happen a dozen times—a tech is a little too rough during installation, a tiny hairline crack forms, and boom. The moment the lamp hits operating temp, the filament burns out. And a heads-up on shortwave tubes: they run hotter to get that specific emission. That puts a lot of stress on your electrical connectors. Check your wiring. If it can’t handle the current, you’re going to start seeing melted terminals, and that’s a headache nobody wants.
The trade-off on the shop floor
Shortwave is the king of speed, but it can be aggressive. If the temperature jump is too steep, you risk “component shock.” Medium-wave is the safer play for sensitive boards. The downside? It takes up more room. You’ll either need more lamps or you’ll have to slow down the belt to get the heat soak you need. So, it really comes down to your priority. If you need raw speed, go shortwave. If you need a precise, gentle thermal profile, stick with medium-wave.