Woven Fabric-based Electrical Circuits

The paper writes about resistive welding as a technique to bond 2 copper wire/thread joint together.

Resistance welding heat is given by:

Heat = I²Rt

• Heat increases with the square of the current

• Higher current → much more heat → more melting/fusion

  Strong weld

• At 1800 A, the heat is sufficient to:

  • Melt copper fibers properly

  • Fuse intersecting yarns together

  • Create low electrical resistance

• This produced the lowest crossover resistance

• This was found to be the optimum weld current

🔹 Weak weld or break

• At 1000 A or 1400 A, less heat is generated

• Less melting → incomplete bonding

• Higher resistance

• Less reliable interconnect

While higher current improves fusion, the text also says:

• At higher current (especially in top-bottom probe welding),
  damage to neighboring non-conducting fibers increases

🔹 Top-bottom probe welding

• Lower resistance

• Lower standard deviation (more uniform)

• More efficient interconnect

• Preferred method

• But:

• Causes more damage to nearby fibers at high current

🔹 Parallel gap welding

In parallel gap welding, two electrodes sit side-by-side on the same surface of the fabric.

Current flows:

• From one electrode

• Through the top yarn

• Down into the crossing yarn

• Back up to the second electrode

So the current path is:

Electrode → yarn → crossover → yarn → electrode

This is different from top-bottom probe welding, where current flows straight vertically through the crossover.

• Higher resistance

• Higher variation

• Can create either:

  • Interconnect (strong bond)

  • Disconnect (intentional break)

The SEM image (Figure 2a) shows that a disconnect can be formed when the weld is created in a way that interrupts current flow instead of fusing fibers properly.

The text also explains:

• Copper forms more efficient welds than steel

• Steel has:

  • Higher bulk resistance

  • Less efficient interconnect formation

So weaker weld performance can also come from:

• Higher intrinsic material resistance

• Less effective fusion behavior

![[DevelopmentofWovenFabric-basedElectricalCircuits.pdf]]