Tools[]
- Anti-static mat
- Work area at "T-shirt" temperature. Cold room may inhibit solder paste adhesion
- Bright light and magnifying glass
- Low temperature lead-free solder paste[1]
- Electric skillet (designated for non-food use) [2]
- (Optional) glass cover for skillet improves heat retention and permits visual inspection
- Non-magnetic stainless steel tweezers to "pick and place" PCB and components [3]
Method 1: Solder Paste Syringe[]
- Clean PCB SMD pads with alcohol on cotton swab to remove oil/dust which would prevent solder paste from sticking to pads
- Apply solder paste to each SMD pad on PCB using syringe. When solder paste melts, solder will pull itself into place on SMD pad. Minimize paste on each pad--too much paste will create solder bridges.
- Use tweezers to place SMD components on PCB, applying slight pressure to "set" each component.
- Preheat (covered) electric skillet to 300F in well-ventilated area
- Put PCB in skillet (and cover)
- Wait till solder melts (~30 seconds)
- Carefully remove PCB from skillet with tweezers. Solder is molten, so parts will be dislodged unless PCB is handled very gently.
- Let cool before handling
Special Considerations[]
Applying solder paste with a syringe:
- Large Pads (>2mm x 2mm): easy
- Small Pads (>1mm x 1mm): possible with practice
- Tiny Pads: not attempted and assumed to be very difficult