Hole quality is subjective to the criteria of the design’s form, fit, and function. Process time or cost may also determine the level of quality required. Laser produced hole quality is assessed in terms of roundness, taper, entrance and exit diameter tolerances, oxidation (i.e. metals), burring or recast layer, and micro-cracking (i.e. glass).
Aspect ratios and material selection are elements that contribute to straight wall or tapered hole profiles. Laser drilling can be used to produce 10um and larger diameter holes in most any material including metals, ceramics, plastics, silicon, rubbers, and glass. MLT laser drilling processes match the optimal wavelength and beam profile for the absorption property of the specified material. These processes are derived from two core laser drilling methodologies, percussion and trepanning.
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Percussion Laser Drilling
Percussion laser drilling is a focused beam of firing pulses (energy) at a single location on a work-piece. Pulse by pulse, the laser ablates material from the hole through the process of melting and vaporizing. The smallest, repeatable hole diameter is about 50% of the actual beam diameter (20um) with controlled taper. This is achieved with a material thickness greater than the beam diameter itself. In most cases, percussion drilling has the advantage of speed over other laser drilling techniques.
Trepan Laser Drilling
The trepanning method is the overlapping of energy in a spiral configuration to cover an area larger than the beam diameter itself. Starting from the diameter center, the beam moves in an increasing spiral diameter until the desired dimension is achieved. Similarly, other custom spiraling pattern files are utilized to create irregular shapes, counter-bores, and slots.
MLT Microvia Drilling Advantage
- Alignment and Scale Methodologies for Minimal Annular Ring Requirements
- Large Via Process Technology that Inhibits Target Pad Delamination
- Lot/Panel Scale Reporting and Analysis for Drill Optimization
- Via Trax ™ Technology for Target Pad Surface Texturing
- Processes for IPC High Density Interconnect Types
- Advanced uVia Diameters Less than 25um
- 100% uVia Vision Inspection (In Development)
CAD or Data Requirements
CAD system integration and custom file converters enable flexible, laser manufacturing from customer-provided data. Although most file types are accepted, the preferred file types for laser drilling are Gerber, Excellon, DXF, or other 2D formats.
For more CAM/CAD guidelines and detailed requirements, click CAD Requirements.