Must Know Things about Solder Paste Stencils – Part 2

Stencils ensure that only the right amount of solder paste is applied to all of the pads on your bare board. In the last post, we have discussed the role of stencils in PCB assembly, how are they used, and common types of stencils. In this post, we will have a look at the benefits of using solder paste stencils and their manufacturing technologies.

Benefits of Using Solder Paste Stencils

When using a solder paste stencil, you will get the following benefits:

• Stencils assure the even applying of solder paste across every SMD pad.
• They allow the application of the paste all at once to the entire board than considering one pad at a time.
• They ensure precise application of solder paste on a substrate, whilst ensuring the formation of properly sized and shaped deposits.
• Solder paste stencils allow you to work easier, faster and accurate, thus reducing the time and labor required to assemble PCBs.
• They guarantee extreme fine pitch accuracy in printing.
• Stencils also help reducing defects and errors even when printing ultra-fine pitch patterns on the board.
• They assure high pad positional accuracy.

Manufacturing Technologies of Stencils

The holes or apertures of solder paste stencils are created by any of the following methods.

• Electroforming: Here, Nickel is electroformed to create the stencil foil.
  Advantages of Electroformed Stencils
  1. Tapered slots
  2. Availability in any thickness
  3. High precision
  Disadvantages Electroformed Stencils
  1. Higher initial cost
  2. Higher processing time
  3. Film tooling required

• Chemical Etching: In this process, excess materials are removed and respective apertures are created through chemical etching.
  Advantages of Chemical Etched Stencils
  1. Low cost
  2. Ability to withstand any known standard cleaning method
  Disadvantages of Chemical Etched Stencils
  1. Rough aperture sidewalls
  2. Slow process
  3. Not environment-friendly

• Laser Cutting: Here, excess materials on the foil are removed and respective apertures are created by laser cutting process.
  Advantages of Laser Cut Stencils
  1. Faster compared to chemical etching
  2. Tapered slots
  3. No film tooling
  Disadvantages Laser-Cut Stencils
  1. Rough aperture sidewalls
  2. Additional Deburring process needed

With these two posts, you would have gained a better understanding of solder paste stencils. You might still have more questions about stencils. Whatever your doubts are, feel free to ask the manufacturer from whom you are sourcing the item. They will guide you better towards an informed purchase.