Here's the straight talk: while resin plugging works great for rigid boards, it's a terrible idea for flexible circuits. Here's why in plain English:

The Stiff Spot Problem

• Flexible circuits are meant to bend

• Resin creates hard, rigid points

• These stiff spots become natural breaking points

• Imagine trying to bend a credit card with a rock glued to it - that's what you're creating

Heat Makes Things Worse

• Flexible materials expand and contract with temperature changes

• The resin expands differently

• This creates stress that can crack the board or break connections

• They basically pull against each other every time the temperature changes

The Manufacturing Process Is Too Rough

• Resin needs high heat to cure (150°C+)

• Flexible materials can handle quick heat (like soldering) but not prolonged baking

• The high pressure during lamination can damage delicate flex materials
  

What Actually Works Instead:

Just Use Coverlay

• This is the standard flexible "mask" we already use

• It naturally covers holes while staying flexible

• No extra processes needed

• It's what the material was designed for

Design Around the Problem

• Put holes in areas that don't bend

• Keep the bending zones clean

• Sometimes the best solution is to avoid the problem entirely

Special Flexible Adhesives (in rare cases)

• Only for non-critical applications

• Still not great for active bending areas

• Usually more trouble than it's worth

The Reality Check:
If you're working with flex circuits, accept that they're different from rigid boards. Don't try to force rigid board solutions onto flexible materials. The resin will eventually crack, the board will fail, and you'll be left with broken products.

Stick with methods designed for flex circuits. Use coverlay, design smart, and save yourself the headache of field failures. When in doubt, talk to your flex board manufacturer early - they've seen what works and what doesn't.