Stenciling and Soldering an Arduino Pro PCB

Introduction

• Presenter: Bob from Fun Electronics.
• Topic: Stenciling an Arduino Pro PCB.
• Assumption: Audience has previous experience with PTH and SMD soldering.

Why Stenciling?

• For finer pitch components and hidden connections (e.g., BGAs).
• Essential for production runs.

Materials Needed

1. Frame for PCB:

   • Holds PCB steady while applying paste.
   • Alternatives: Use junk PCBs and tape them around the target PCB.

2. Solder Paste:

   • 500g jar (lead-free for production).
   • 10g jar (leaded).
   • Storage: Cool, dry place like a fridge or room temperature for short periods.
   • Airtight container to prevent waste.

3. PCB:

   • Single or panelized boards.
   • Panelized boards provide efficiency in build times.

4. Stencil:

   • Kapton plastic or stainless steel.
   • Metal stencils provide durability and cost-effectiveness for high usage.
   • Plastic stencils are more affordable but less durable.

5. Putty Knife:

   • Used for applying solder paste.

Stenciling Process

1. Setup:

   • Place PCB in frame or create a framework with spare PCBs.
   • Tape down the frame to secure.

2. Applying Solder Paste:

   • Use a putty knife to scoop and apply solder paste evenly.
   • Lay stencil over PCB, align holes with PCB footprint.
   • Apply paste with putty knife at a 45-degree angle.
   • Scrape off excess paste at a steeper angle (up to 90 degrees).

3. Finishing Up:

   • Gently lift stencil to avoid smearing.
   • Inspect PCB for even paste coverage.

4. Cleanup:

   • Scrape off excess solder paste.
   • Wash hands as paste is often water-soluble.
   • Consider using gloves and safety glasses.

Populating and Reflowing

1. Populating Board:

   • Start with smaller components (caps, resistors).
   • Work up to larger components.
   • Ensure proper placement of polarized components.

2. Reflowing:

   • Options range from reflow oven to soldering iron.
   • Demonstration uses a hot plate.

Conclusion

• Summary of the stenciling process.
• Encouragement and best wishes for future stenciling endeavors.