Cavity PCB fabrication requires a lot of patience. In cavity PCB manufacturing, you need to pay special attention to some details, which will determine the success or failure of cavity PCB.
Micron laser technology has a special Cavity PCB peeling process. The cavity wall can be formed by using etched or laser ablated copper openings as masks or directly on the exposed dielectric. Although the aspect ratio is greater than 1:1, the cavity formed by etching copper with the required cavity size can form a straight wall with minimum taper.
Depending on the material and its depth, the cavity wall tends to be conical along the wall height. MLT programming technology can reduce the effective taper to less than 10% of the cavity depth.
The most cost-effective cavity falls on the etched area of the metal layer. With appropriate infrared wavelength energy transfer, the dielectric absorbs the laser energy, but the metal reflects the energy to leave a clean surface for electroplating, wire bonding or reflow.
Cavity PCB fabrication need to dielectric removal：
Controlling the depth cavity cutting by MLT can complete the creation of a cavity that stops on the etching circuit layer. MLT controls depth, cavity scraping uses customized programming techniques and uses the correct spatial and temporal laser beam profile to evenly distribute energy in the cavity area.
As the processing depth of the laser cavity reaches within 25um-50um of the required depth, ablation is switched from high-energy or “coarse” delivery to low-energy or “fine” delivery for multiple processing. This fine ablation scraping removes the dielectric from the circuit surface and stops directly below the etched circuit plane.
Cavity PCB fabrication need to provide UV laser to remove carbon pollution：
If the standard coating preparation is not sufficient to remove some micron scale contamination that inhibits the coating, the MLT will provide UV laser to the cavity surface to remove carbon contamination that may not be visible at the infrared wavelength.
The processing time or cost of laser cavity depends on the total amount of material removed. When the cavity depth exceeds 0.008 inch, mechanical pre grinding the cavity to within 5 mils of the target layer before laser processing can greatly reduce the cost of laser cavity peeling. The laser scraping of PCB cavity may be limited by some material accumulation and tolerance. Please contact our sales staff to discuss your PCB cavity requirements.