Flexible Circuit Laser Processing

industrial laser
application note

Flexible Circuit Laser Processing

Figure 2. Precision cutting and narrow cut widths mean less material wasted. Non-contact cutting means going straight from CAD software to complex shapes instantly.

Figure 3. UV lasers provide excellent, high resolution edge quality with no burrs, debris or strands. More importantly, UV lasers result in cleaner processing with no burned edges, virtually no carbon residue, and minimal thermal degradation of the material.

Smaller, denser, and lighter is the future of flexible circuit manufacturing. Flex circuits are used extensively in automobiles, hard disc drives, digital cameras, cell phones and PDAs, telecommunications equipments, laptops, displays, IC packaging and medical devices.

Because of excellent wear resistance, chemical stability, high working temperatures, and low flammability, the vast majority of flex circuits are based on polyimide substrates. Depending on the PCB material type, DPSS Q-switched UV or green lasers are commonly used for three key manufacturing processes of flexible circuits:

  • Via Drilling – both blind vias and through hole vias
  • Ablation – of top dielectric layer of the conductor
  • Singulation – cutting of the flex circuit pattern

Laser micromachining offers powerful advantages to traditional flex circuit machining technologies such as die cutting and stamping:

  • Superior Edge Quality – Complex patterns can be cut quickly with minimal carbonization, debris or strands
  • Precision – Accuracy through vision alignment and precise pattern cutting registration
  • Higher Resolution – Higher circuit density
  • Narrower Cut Widths – Less material wasted
  • Flexibility – Faster and less expensive setup for short production runs since CAD design changes of slots, holes, or overall shape can be implemented instantly
  • No Ongoing Tooling Costs – Die wear is eliminated with non-contact laser processing

UV laser micromachining offers significant advantages to CO2 laser processing:

  • Higher Resolution – Typical spot sizes at the circuit of <20 µm enable smaller features, higher circuit density, and circuitry closer to the edge.
  • Cleaner Processing – Features have almost no burned edges and leave behind virtually no carbon residue.

Less Thermal Degradation – Rather than a melting process (as with CO2), the high peak power and short pulse width UV lasers vaporize much of the ablated material and produce far less heat affected zone. With higher density circuits, thermal degradation becomes less and less acceptable.