1. The biggest difficulty of excimer lasers is their slow drilling speed and high processing costs. Therefore, they are limited to the production of high-precision, high-reliability micro-holes.

2. The impact carbon dioxide laser typically uses carbon dioxide gas as its laser source, emitting infrared rays. Unlike excimer lasers, which burn and decompose resin molecules through thermal effects, carbon dioxide lasers operate via thermal decomposition.

3. Consequently, the shape of the processed holes is generally inferior to that produced by excimer lasers. The aperture size that can be processed is typically in the range of 70-100 µm, but the processing speed is significantly faster than that of excimer lasers, and the drilling costs are considerably lower.

4. However, even with these advantages, the processing cost remains much higher than that of the plasma etching and chemical etching methods described below, especially when the number of holes per unit area is large.

5. It should be noted that when using impact carbon dioxide lasers to process blind holes, the laser can only be directed at the surface of the copper foil, and there is no need to remove the organic matter on the surface.

6. To ensure stable cleaning of the copper surface, chemical etching or plasma etching should be used as a post-treatment. Considering the technological feasibility, the laser drilling process is not particularly difficult to integrate into the tape process.

7. However, when balancing process efficiency and equipment investment, it does not present a clear advantage. Still, the ribbon chip automatic welding process (TAB, Tape Automated Bonding) has a narrow width, and utilizing tape-reel technology can enhance drilling speeds.

8. Practical examples of this application have been documented.

9. The above discusses the differences in through-hole technology for flexible circuit boards.

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