Micro Manufacturing in the USA with Scan Head guided Nano Second MOPA Lasers

A Job Shop Owner’s View

Mark Brodsky

Laser Mark’s Company

August 19, 2014

Manufacturing in the USA is not dead. It is though highly specific to demands of customization. While thousands of manufacturing tasks have gone to Asia, there is still a niche market for customization of products and processes. Nanosecond lasers are still a useful tool for those developing technologies and materials that are outside the realm of high volume manufacturing.

In the past 25 years nearly all the silicon has left Silicon Valley. A combination of taxation on capital, unreliable power, and local politics added to the drivers of high labor and living costs to push away wafer fabrication. Marking semiconductor chips and packages went from being 90% of a job shop’s tasks to less than 5% currently. And yet there are still hundreds of local shops that require the application of photons for their products to succeed.

The major use for scan head guilder lasers is still general purpose marking. The materials being marked are far more diverse than even 10 years ago and vary from custom aluminum anodizations, steels, titanium, and exotic ceramics. Additionally, products now commonly marked are typically smaller and more specialized then routine machine tool part identification. For example the marking of a ceramic knuckle joint requires care not to destroy the integrity of the ceramic surface while still providing high visual contrast . Such marking is performed using MOPA fiber lasers where both pulse width, and kHz can be adjusted independently of either the average power or the individual pulse energy. Thus a mark is basically tuned to match the need of the material being processed.

Photo Ceramic Knuckle Marking that insures surface integrity as well as high contrast resolution

Photo 2 Cutting of 1mm thick Silicon

New MOPA fiber lasers allow for precision etching of materials at depth. 1mm thick silicon can be cleanly cut with no post cleaning greater than a Q-tip wipe by utilizing the great depth of field and high power density of single mode fibers. Here a 30 watt Single Mode fiber cut out a 1mm circle, inside a 5 mm window frame square. The kerf width is a function of the material thickness because, like all scanning laser applications, space must be made for the ablated material to be removed. In this case a kerf angle 5 degrees was achieved with a cutting rate of 11mm/min and a 200 micron kerf width. Multiple passes at a variety of settings are used to achieve this clean cutting effect. Again the key to cutting is the use of a MOPA with adjustable kHz and pulse width that does not affect the peak pulse power.

MOPA fiber lasers are also used in the MEMS/Semiconductor industry. It is far less expensive to modify an existing semiconductor package such as a plastic leaded chip carrier (PLCC), than it is to make a new custom plastic mold with a cavity for the MEMS device. This is done by having the laser both etch and then clean out a viable cavity in an existing empty PLCC package. The MOPA fiber allows for both long and large energy pulses to remove bulk plastic, followed by gentle clean “nibbles” to clean the gold plated contact lead tips. Note from the photo that the plastic has been precisely removed to the same depth as the cleaned leads. This would be impossible with out the ability to shift on the fly between wave forms!

Photo 3 Etching of a MEMS cavity into a standard PLCC package

Photo 4 Old DBY still has a home for large and oddball processing

Jobs shops have to be flexible to accommodate all types of customer requirements. There is still a place to utilize the older Diode Pumped YAG technology when odd and large parts need adjustment, part number correction or etching off of coatings and films.

However many customers require more precision processing. When tasks can not be performed in a job shop, a custom laser system is in order. Laser Mark’s Company produces only a handful of these more complex units, and they are made in conjunction with the development of highly proprietary laser processes. Below is an example of one such system used for micro machining. It utilizes a MOPA laser capable of a 3 nano second pulse combined with optics capable of a 9micron spot size over a 30mm field. In systems like this, the precision motion stage and targeting optics adds the most to the cost of the laser system.

Photo 5 Precision micro machining system with through the lens targeting designed for custom use by Laser Mark’s Company

Photo 6 Etch, Clean and Dark Anneal Marking using a 20W MOPA fiber

However all is not high tech, even in the remains of Silicon valley. Thousands of different marking jobs come through my shops doors. And while most are highly technical, there is still room and profit to be had from utilizing micro machining tools for more fun projects. This lock will find many years of use on a bridge in Paris.