MEL

Laser Cutting • Trimming • Drilling • Ablation • Etching

MEL-40 performs many different automated functions.

The use of lasers in processing microelectronic devices, such as the trimming of thick and thin film resistors is so well established that the laser has become a common tool. This is especially true for high-volume, high-accuracy trimming applications. Modern equipment, such as California Digital’s MEL-40 Laser Trimming System, provides both thick and thin film hybrid resistor trimming in active as well as passive modes. Such tools accommodate all common cut types, including L, J, U, plunge, double plunge and serpentine. This precision unit delivers trim accuracy as high as 0.1 percent, measuring accuracy of 100 ppm, and a range of 0.1 ohm to 1gigaohms. California Digital is well known for its ability to provide custom machinery for specialized applications. This includes trimmers that can handle substrates as large as 1 x 1 m.

Available enhancements to the MEL-40 include automatic focus and pattern recognition. Auto-focus determines the best focus and is fast (in the millisecond range), repeatable and operator-independent. Pattern recognition, also known as machine vision, permits complete hands off operation

A laser machine must be versatile. The MEL-40, for example, can be fitted with a number of other options for whatever micromachining is required. Standard output of an arc lamp pumped YAG laser is at an infrared wavelength of 1064 nm, but is available in green (532 nm) and ultraviolet (355 nm and 266 nm) wavelengths to provide for processing materials of specific properties. For example, quad YAG (UV @ 266nm) avoids heat affect and is an excimer alternative for some applications. It’s good for glass, plastic and epoxies. However, it’s low output is a limitation vis a vis excimer. Doubled YAG is good for Si processing due to its higher power, green output and micron spots. Diode pumped YAG is ideal for resistor trimming, thin film scribing and applications requiring low power with high pulse-to-pulse stability. The MEL-40 can also be supplied with a CO₂laser for Kapton, ceramic and metal processing (cutting, via hole drilling and substrate scribing) in applications involving computer connectors, hybrid surface mount and flat panel displays.

True flexibility also means the laser can be modified simply and quickly to perform a variety of other tasks. A frequency doubled green laser beam can be used to anneal silicon into polysilicon resistors. The MEL-40 also is adaptable for a number of micromachining applications, including cutting, drilling, scribing, pattern generation, and marking (including glass). Marking is both bar coding and alphanumeric. ITO patterning is another upcoming application for creating conductive, transparent display areas. Patterning and other micromachining are expedited by Autocad/Gerber download to the MEL-40.

Cut, drill, scribe and ablate metals, ceramics, silicon and thin materials within the tolerances of 1-micron. California Digital’s standard MEL-40 MicroElectronic Laser trimming center produces all these microscopic laser operation in an area up to eight-inches square.

The MEL-40 laser is controllable by the systems internal computer or in conjunction with the operator’s external computer connected to external instrumentation and measuring devices.

The results we have seen prove that the newer diode pumped YAG laser offers greater output stability and better beam quality for processing thin films, especially when removing one layer directly over a second layer. This requires power and stage speed stability. Variations in either of these components can cause under or over removal during processing. Note that the arc lamp pumped YAG requires 220 VAC with 3-phase power. Diode pumped YAG, on the other hand, needs only single phase and 110 VAC. And diode lasers require replacement of the diode assembly every 5000 hours or so, a very costly process. In contrast inexpensive arc lamps are replaced every 40 to 500 hours. We find that, in general, diodes provide better processing features than those found with arc lamp pumped lasers. However, high price and low power are the two limiting features of diode technology today.

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For More Information, e-mail Us at: laser@cadigital.com