Shortwave vs. Medium-Wave Quartz Lamps: Which one actually works for SMT?
If you’re putting together an SMT line for something as finicky as smartwatch repair, you’ve probably realized that heat is everything. Get it wrong, and you’re looking at warped boards or ruined components. That’s why most of us stick with quartz lamps—they can take the heat without just snapping. But then you have to choose between shortwave and medium-wave. It sounds like a technicality, but it totally changes how your day goes. The speed factor Shortwave IR is basically the “fast forward” button. It hits the PCB and the components almost instantly, pushing them up to soldering temperature before you’ve even blinked. It’s great when you’re in a rush. Medium-wave is a different beast. It’s more about a slow, steady soak. It spreads the heat out more evenly, but it takes its sweet time getting to that peak temperature you need for lead-free solder. What’s actually inside the tube? We use high-purity quartz because it lets the IR radiation fly right through. Here’s the catch: if the quartz is cheap or impure, the tube starts absorbing its own heat. That’s a recipe for a burnout. Most of these use a tungsten filament. With shortwave, we crank that filament up to insane temperatures to get the heat density we need. It works, but it definitely puts the filament through the wringer. The trade-offs (and the risks) Shortwave is the way to go if you want to slash your pre-heating time. But you have to be careful. If your lamps aren’t positioned perfectly, you’ll get “hot spots.” One wrong move and you’ve popped a capacitor or warped a thin smartwatch substrate. It’s all about dialing in that dwell time. Medium-wave is a bit more forgiving. It’s a safer bet for thicker boards where you need the heat to seep all the way through without torching the top layer. One last thing—don’t cheap out on the wiring. Use high-temp leads. If your connectors aren’t rated for the current these high-wattage tubes pull, they’ll literally melt right in front of you. Not a great look.