Powering the Future: Why True Ceramic Circuits Are Not Just ‘Better PCBs’
Global Sourcing Spotlight: The Global Quality Gap—Why Consistency Wins the Contract
Knocking Down the Bone Pile: Precision Milling of Underfilled SMT Components
Figure 12: Comparing temperatures in different materials.
Because different efforts are needed to cut through different materials, different cutting times result and for the more difficult situations higher temperatures are being measured. Still the temperatures at a distance of about 0.1 mm remain quite acceptable.
Quality vs. Time
As mentioned, the laser beam does apply some heat to the workpiece. In order to minimize the impact of the heat the beam is scanned multiple times over the cutting path to distribute and minimize heat build-up. For this reason, the beam control system allows adjustment of the movement speed and beam power, but it is also possible to insert rest periods between cutting paths. These rest periods are more important when the cutting path is short and the beam would be back in the same location more quickly.
When board layout and component placement are done well away from the sides of the individual boards, the cleanliness of the sidewalls is of less concern and the laser parameters can be selected for maximum cutting speed, meaning higher beam power, faster beam speed and shorter rest periods between cutting paths.
On the other hand, when the cleanliness of the sidewall is critical, more care has to be taken in the selection of the machine settings. Figure 13 presents a visual difference between these two strategies.
Figure 13: Visual difference between high quality/low speed and fast speed/lower quality.
Surface Analysis
To determine the spectrum of chemical components left on the cut surface the energy dispersive X-ray (EDX) analysis method was performed. For reference a routed sidewall was carefully polished and cleaned to show the normal composition of a board. Spectral lines from four chemical components are displayed in false color for the polished sidewall (Figure 14) and for the laser cut sidewall (Figure 15). The variation is too small to expect significant issues.
Figure 14: Polished and cleaned sidewall.
Figure 15: Untreated laser-cut sidewall.
Page 4 of 6
