PhotoMachining - Laser Micromachining and Microfabrication Systems and Laser Contract Manufacturing

Frequently Asked Questions (FAQ)

a) What is the smallest hole diameter you can drill?

Smallest achievable hole size (and largest achievable hole size) is dependent on the material, material thickness and laser used. It is possible to drill 1 micron holes through thin material at aspect ratios of up to 100 to 1. It must be remembered, however, that there will usually be taper associated with the holes and the entrance diameter will be larger than the exit. We normally specify EXIT diameters. As a rule of thumb, the minimum hole diameter achievable with a CO₂ laser is about 50 microns and the minimum achievable with an excimer laser is 2 microns. With the optical setups currently in our lab, the tripled YAG laser can go down to about 20um.

b) What is the thickest material you can drill through?

We generally define 'micromachining' to mean feature sizes of less than one mm in diameter and in most cases less than a few hundred microns. Similarly, we usually define this to mean material thicknesses of less than one mm and usually less than a few hundred microns. Because of the taper associated with laser drilled holes, it is usually true that, as part thickness increases, minimum attainable hole sizes also increase and it may be harder to hold tight tolerances. It is essential, because of the taper, that parts have uniform thickness and are flat (not bowed or warped). In some cases we have been able to drill through several millimeters of materials like ceramic.

c) What can you say about part cleanliness or debris?

Lasers are excellent marking tools on most materials, and there is a chance that there may be discoloration of material around the laser processed area. In marking applications this is of course desirable, but in other applications it may not be. Usually material removed with a laser will be very small in size and will either be carried away by the assist gas and ventilation during processing or will fall back onto the top of the part as debris which is easily cleaned. As a general rule, UV lasers produce much less charring, melting or debris than red lasers such as the CO₂. In some applications, such as microvia drilling with the CO₂ laser, a post process plasma etch may be necessary for platability.

Sometimes an assist gas such as helium, nitrogen or dry shop air is used during processing in order to minimize debris.

Unless other arrangements are made in advance, PhotoMachining returns parts to the customer uncleaned and as they come off of the laser.

d) What is the expected taper?

Taper is usually introduced as a result of the laser drilling process and the entrance diameter is usually larger than the exit diameter. Taper increases with decreasing laser fluence on target and to a certain extent may be controllable. Taper issues also become more important as hole sizes decrease and part thickness increases. As a general rule, expect about 6 to 10 degrees included angle taper. Larger tapers can also be made through clever set up of optics and beam delivery.

e) Are your lasers operated in a controlled environment?

All micromachining lasers at PhotoMachining are located in a hardwalled cleanroom or cleantent. The temperature of the cleanroom is controlled to within a couple of degrees, and the humidity within a couple of percent. The laser processing room is capable of achieving Class 10,000 or better if needed. While we typically do not gown unless the job requires it, we can offer this as a service to medical, aerospace, or other customers who need the ultimate in cleanliness.

f) Explain the different types of beam delivery you use.

Some micromachining workstations that we build and also that we use in house have a fixed beam delivery system. Part motion is then accomplished using x/y tables. Another option is to fix the part and move the beam. There are two ways to do this. First, either the laser or the optics can be mounted to 'flying' beam delivery components. The second option is to use high-speed galvanometers. These are small devices that are mounted orthogonal to one another and that move the beam over a fixed area. The accessible area is defined by the galvanometer deflection, usually about 20 degrees, and by the distance from the work surface. The accessible area is also limited by the field of the lens if a flat imaging lens is used. The larger the galvo field, the larger the minimum acheivable spot size. Spot size is also affected by the size of the input aperture.

In some cases, both moving beam and moving parts are integrated into one platform in order to access larger areas on target.

In general, higher precision and accuracy can be obtained using x/y tables and higher processing speeds can be obtained using galvanometer beam steering.

g) What type of analytical instruments do you have?

We have high resolution optical microscopes in our laboratory. We also have coordinate measuring systems. SEM work is also available at an additional charge. More information can be found in Services->Analytical.

h) How expensive is laser processing?

This is usually one of the first questions asked and it depends on many factors. The most important is the choice of laser used. Excimer or other UV lasers are generally much more expensive to build and operate than infrared lasers like the CO₂, therefore the processing costs are higher. Also, the infrared lasers, while less controllable than UV lasers, are much faster because of their higher power output and larger penetration depth. In general, the following factors apply:

• $500 optical set up on excimer llasers which is recurring with each lot run.

• $500 optical set up on picosecond and femtosecond lasers which is recurring with each lot run.

• $300 optical set up on CO₂ and fiber lasers which is recurring with each lot run.

• $350 optical set up on frequency tripled Nd:YAG lasers which is recurring with each lot run.

• $400 optical set up on frequency quadrupled Nd:YAG lasers which is recurring with each lot run.

• Part prices dependent on laser, part thickness, number of features, number of parts run per batch, committed volume of customer, etc.

• One Day parameter studies with senior level engineer (customer is encouraged to be present) is billed at $200/hr. ($350/hr for picosecond and femotsecond lasers, $250/hr for nanosecond, fiber, CO₂ and $500/hr for excimer lasers)

• Tooling costs or programming costs may also be incurred if needed.

• Repeat jobs or long-term contracts may incur reduced setup charges if the job is done on an ongoing basis, and prior arrangements have been agreed upon.

i) What are your field service rates?

In general, we try to be a "quick return: shop and hold to turn around times of less than one week.

PhotoMachining’s standard cost for on-site field service is $200/hour with a 4 hour minimum. We also charge $100/hour for travel time for trips with > 2 hours travel time. Per diem expenses of $250/day are also charged. Airfare is charged and passed along at the same rate that we pay the airline. Per diem expenses cover meals, lodging, rental car and other auto expenses (fuel, tolls, etc.).

j) What is your turn around time?

For excimer laser processing, we quote 1 to 2 weeks (more if tooling or masks are needed). We will quote priority processing fees of $500 for guaranteed shipment less than one week and $1000 for guaranteed shipment less than 48 hours, provided that no tooling or masks are required.

For microvia drilling, we quote less than one week guaranteed shipment and will offer priority processing ( < 48 hours ) for an additional charge. Most tripled YAG and CO₂ work can be turned around in 1-2 weeks.

Please contact the factory for details.

k) How do I go about getting a quotation for job shop work?

It is best to phone and discuss your application with a technical sales engineer - contact information is located here. We will need to know a little bit about your application and in particular the material, material thickness, description of the job to be done (a DXF file), the number of parts to be laser processed, etc. DXF files can be sent to sales@photomachining.com along with a description of the job. A quotation will be generated (make sure to include your contact information in the case we have questions) and sent to you. Typical terms are FOB Pelham, NH and NET 30. We also accept credit card orders.

l) I am not sure if laser processing is right for me. Will you do 'free' samples?

While for proprietary reasons we do not provide samples of work that we have done, we will in some cases process some of your material at no charge. Our general policy is that we make simple cuts or holes in material in order to give first order feedback to you. We do not guarantee any particular hole size, spacing, etc. on 'free' samples. These samples are done on a non-priority basis when a 'similar' optical set up is being used. We return ship by UPS ground. If you require express shipping, please include your Fedex, UPS, or other express carrier account number, so we can bill your account (since we do not require PO #'s for samples).

m) Do you provide material?

We do not provide material. Material is sent to us by our customers and it is this material that we use for processing. In some simple cases we can provide material such as Kapton® or Mylar®. If jobs are recurring and we receive a long term commitment for laser processing, we will consider providing material and integrating the cost into our quotation, but this is normally reserved for 'production' customers.

n) What facilities will I need in order to bring a laser processing system in house?

This depends to a certain extent on the type of laser system. Since we are involved in only micromachining applications, the facility requirements are generally relatively low. Electrical requirements are usually 208 V single or 3 phase with about 30 Amps per circuit. Most, but not all, lasers require cooling water of some sort. This can be either house water, or a chiller can be used. It is frequently helpful to have ventilation in order to carry away any effluent generated by the laser. This becomes more important with the CO₂ laser and especially if the materials to be processed are plastics. If no house ventilation is available, we can supply a fume extraction and filter unit at additional charge. Also, a house vacuum or vacuum pump are required if a vacuum chuck, such as the PhotoMachining porous ceramic chuck is to be used. Finally, gases may be necessary either to run the laser or to use as an assist gas. This is especially true of excimer lasers. These lasers use combinations of halogen and rare gases to achieve lasing output. PhotoMachining will quote a gas cabinet where needed.

o) Can I come to visit the facility?

Certainly! In many cases, we encourage you to come in and see firsthand the results of laser processing and the work involved therein. Directions can be found within the information section, under Contact Us. If you choose to come see us, there are a few things we require of you: