Optomechanical Engineering: Atmospheric Challenges for Ground Based Telescopes

Most astronomy is performed using ground based telescopes throughout the world. From the amateur astronomer using a small portable telescope, to the large optical telescope systems found at observatories, these optical instruments have a wide range of applications. There are also radio frequency telescopes, such as the ones located nearby at Stanford University. 

One may easily access and adjust ground based telescopes, unlike space based telescopes. However, for optomechanical engineers, just because something is accessible doesn’t mean it’s easily adjustable.

One of the largest disadvantages to ground based telescopes is that the light (or signal) must pass through the atmosphere, which may degrade it. For this reason, astronomers place most large ground based telescopes in remotely located observatories with little light pollution. Astronomers favor mountain tops for their thinner atmospheres, because it results in less observational distortions. Although higher elevation locations aid in producing clearer observations, the temperature variations cause mis-alignment.

Before optomechanical engineers developed active optics, whenever there were shifts in temperature, astronomers had to adjust heavy observation mirrors using laborious and time consuming manual adjustments. Mechanical engineers perform extensive stress analysis, and vibration mode analysis, usually by finite element analysis (FEA), but the structures still suffer misalignment due to wind, vibration, temperature change, solar radiation, and other factors.

Active optics offers some relief by breaking up the large primary and secondary mirrors into a series of thinner and smaller mirror segments that resemble the shape of a honeycomb. Behind each mirror segment are actuators. Optomechanical engineers, with the help of electrical engineers and control systems engineers, design actuators and control systems, to compensate for misalignment. The computer software, developed by control systems engineers, collects the information, e.g. temperature, and sends out a series of commands to adjust the mirrors accordingly. The thinness of the mirrors paired with the sensory information gathered and adjusted by the actuators, provides observers with a more accurate method for obtaining images.

This new technology has been implemented into large telescopes built in the last decade, and is still evolving. Optomechanical engineers utilize better materials and methodologies, to obtain better results. Given the changes to active optics in the last decade, the saying, “the sky is the limit” takes on a whole new meaning. 

 

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

LED Lighting: Transitioning Away from Incandescent Lights

Incandescent lights, despite inefficiencies and poor reliability under power cycling, are only recently beginning to be phased out for more energy efficient options. This transition draws a striking resemblance to another technological advancement in the middle of the last century. The first computer used vacuum bulbs and required massive amounts of energy to operate. The introduction of semiconductors revolutionized the industry and made computers, a relatively exotic device at the time, available to the masses. The lighting industry now appears at a similar transition point, with a payoff in energy efficiency as well as a huge profit potential.

One technology making headway is Light-Emitting Diode (LED) lights. A diode is a simple semiconductor device.Initially incandescent lights had the upper hand on LED lighting because they generate continuous spectrum emission and are therefore, more pleasing to the eye. This is about to change. Transition to home LED lighting is well underway with LED engineering teams directing their attention to generating a color spectrum to produce light that is familiar to the human eye. Industrial, street and automotive lighting are further developed in this transition, i.e. they are in full production mode. Automotive lighting engineers aren’t as concerned with a driver being able to see all the color hues of a deer’s coat as long as the driver can see the deer in time to break. LED Lighting is also beneficial in applications wherein maintenance is difficult, such as the Chunnel.   

Currently though, there is one important distinction that needs to be made for the thermal management of incandescent lights vs. LEDs. A typical incandescent light is usually designed to achieve the highest possible temperature without, plainly speaking, melting, the resistive element. Conversely, LED lighting is happiest at the lowest possible  temperatures. High-power LED's often require use of heat-sinks and quality thermal interface materials. Thermal engineering is of the domain of mechanical engineering; FEA is the tool of choice to analyze the thermal problem.

Although there are obvious challenges, the benefits of LED lighting far outweigh the struggle. In addition to power efficiency, the lifespan of an LED far surpasses the minimal life of incandescent lights, by thousand of hours. This makes LED technology the poster child for legislation moving away from incandescent lights and towards more efficient lighting technology.

 

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

Optomechanical Engineering Considerations for Space Instruments

When designing optical instruments for space vehicles, one must take specific into account certain considerations, to ensure successful performance capabilities. This blog hopes to introduce the following: (1) the importance of material selection; (2) environmental considerations; and (3) challenges that optomechanical engineering teams encounter.

Effective engineering design of optical instruments requires advance knowledge of the adverse environments under which the product is expected to successfully operate, e.g.  temperature, pressure, vibration, shock, moisture, corrosion, contamination, fungus, abrasion, erosion, and high radiation. These all can affect the performance of optical instruments and their useful life cycle in space and elsewhere. The optomechanical engineer must carefully select the materials to maximize environmental resistance, in order to ensure the proper operation of the product over the expected useful lifetime.  Often an optomechanical engineer relies on the combined skills of an engineering team composed of other specialists.  Mechanical engineers may perform FEA to determine stress and vibration; electrical engineers may help design the controls and electronics.  Materials scientists and materials engineers help to specify and test the materials of design.  Ocassionally, one even finds a use for a physicist.

Environmental conditions in space vary widely, and may be severe.  In the extreme conditions of space, optical instruments must be able to survive without progressive deterioration or permanent damage, yet still perform in accordance with project specifications. Therefore, defining the expected environment of the optical instruments in space as well as under launch, operating, storage and transportation logistics are absolutely critical. All conditions must be managed as early in the design phase as possible to ensure appropriate provisions are made.

Space provides a harsh environment that challenges scientists, and engineers to meet design optical payload requirements in this type of environment. Various environments exist for operation, storage, and transportation of flight hardware such as optical systems. In a controlled environment, such as a laboratory, the product would have a different set of conditions than a system designed for the military, or space flight.

One common mistake novice optomechanical engineering teams make when designing for space is to neglect the vacuum of space. Human beings are used to atmospheric pressure of 101 kPa (14.7 psi) and 21% oxygen. Astronauts require this ambient pressure, but it creates an internal pressure on a space vehicle. The pressure differentials can cause fractures or deformations in the structure, loss of hardware functionality, even explosions, not to mention millions of dollars lost on the project.

An example of this is an optomechanical engineering team forgot to take pressure differentials into account when design a portion of a satellite. One of the multi layer insulation blankets came loose and covered up most of the optical mirror. This essentially took away most of the satellite’s vision and resulted in limited data retrieval.

Space is the final frontier and represents a myriad of unknowns that can compromise space vehicles used for human exploration. Optomechanical engineering personnel must attempt to account for all of the conditions that could affect their optical instruments, or risk damaged equipment and million dollars wasted. 

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

IC Thermal Management: Electronic systems reliability & power cycling

 

                  Device reliability under changing temperature is one of the most difficult tasks when packaging semiconductor devices.  A typical test involves subjecting a packaged device to 0 - 100 degree C  temperature range, with residency times designed to induce a suspected failure mode.  Standard temperature  cycling tests can be performed inexpensively in large scale allowing for good testing statistics.  Typically, component (IC) manufacturers use this test during development phases when exploring new packaging configurations. LED manufacturers and MEMs manufacturers can utilize this method.

                  The product companies, which deliver directly to consumer, attach high importance to testing the system as a whole, as opposed to just a package or semiconductor power cycling.  Power cycling becomes one of typical system tests.  Power cycling involves powering the whole system in a cyclical manner to look into most vulnerable failure modes, majority of which are associated with the modulated CTE mismatch driven stresses.  While seemingly simple in concept, thermal management of devices plays key role on performing this out-the-door sanity check: without a heat sink, for example, device operation may not be possible at all.   

                  Stated simply, the thermal solution must ensure the same temperature envelope during the field operation that the component was tested for.  If a component, i.e. CPU, underwent testing between 0 and 100 C, as an example, thermal solution must be able to keep the device operation in this temperature envelope.  While as usual, complications arise, one can state to the first order (combined electro-thermal failure modes use different testing protocols) that power cycling from thermal perspective is the test of thermal solution. 

                  Second important effect that needs testing is the added mechanical loads from putting the component in to the system: they may induce a stress field different from when testing components.  An example is the case of BGA packaging. where additional CTE-mismatch driven effects are introduced at board assembly.  This scenario can still be accounted for by the component maker when testing assembled boards in temperature cycled environment. 

                  There is a gap between power and temperature cycling test, which can be substantial.  Temperature cycling, mostly developed as a quick way of looking into field reliability, could be either too constrictive leading to over-engineered and costly manufacturing or not be able to screen out all potential field failures which is an even worse of a scenario.  Power cycling tests can be difficult to set up and configure.  Temperature cycling is rather straight forward.

                  Power cycling is usually the domain of reliability engineers.  Different engineering disciplines can function as reliability engineers.  Generally, mechanical engineers, materials engineers, and electrical engineers perform these functions. 

                  There are certain material sets that were developed using power cycling reliability as opposed to intermediate step of temperature cycle testing. This type of development activity is costly due to having to develop power cycling equipment needing precise control of power delivery and dissipation as well as accurate thermal characterization.  Glew Engineering can assist with your efforts on developing cost-effective reliable electronics, reliability engineering, and power cycling.

 

 

 

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

Who may use engineering titles. PROFESSIONAL ENGINEERS ACT §6704

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

Leveraging a Third Party Engineering Firm for Medical Device Development

A third party outsourced mechanical engineer, electrical engineer, materials engineer, and engineering teams from engineering consulting firms can provide support to the medical device industry

Recent changes in regulations regarding the manufacturing of medical device benefit the U.S. medical device manufacturers. It now makes financial sense for manufacturers to bring home some of the work that has been done overseas for the last few decades.

Some medical device companies are adding a third party consulting mechanical engineer, electrical engineer, and materials engineer to beef up their medical device engineering teams. Other firms will see benefits in outsourcing to third party firms to complete, expand, or speed up projects. Others may outsource temporarily, or add staff on some projects while outsourcing parts of other projects.
Outsourcing work to an engineering consulting firm has several benefits. With the world economy in difficult straights, adding staff is risky.

Dedicating funds to adding office space for the long term carries the risk of tying your firm up with debt or stripping it of cash reserves in the face of a potential recession.  Furthermore, an engineering firm can bring solutions that from other industries to the medical device field.
Finding specific expertise might also be a challenge. If your project is time constrained, you may not have time for an extended search for a person that is a right fit with your team. Future projects may not warrant a full time individual or group with the specific skills your current medical device project requires.

If you’re looking for specific experience in a mechanical engineer for medical device manufacturing, mechanical engineer consulting firms may have the right person available immediately. More generalized firms can supply a team with varied expertise, including a materials engineer,electrical engineer, process engineer, and software engineer. Perhaps more important still, these individuals may have worked as a team on many projects already and have strong and stable team dynamics.

Leveraging third party engineering groups won’t be the right solution for all firms. If your company has firm long-term demand requiring a dedicated mechanical engineer, electrical engineer, or materials engineer, or an excess of ready cash, very low debt, or spare office space, the risks of adding staff are smaller. And, of course, many firms will find it advantageous to split the difference, bringing in new staff where they see longer term demand or where more general skills are needed.For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

IC Thermal Management Part 3: Underfill TG

IC Thermal Management Part 3: Underfill glass transition temperature, TG:

In preceding blogs  we talked about the challenges that are associated with the thermal management of IC's.  Let's have a brief summary.

1) The very first task is to obtain accurate information on which to act. We'd like to have accurate temperature readouts at relevant locations, which was the subject of the first entry. 

2) The dissipated power must be transported away to the outside environment, often using some form of air mover.  Constructing optimal cooling solutions for best user experience was the subject for the second entry.  One has to balance the performance needs with the power requirements while delivering acceptable acoustics, as an example.  Choice of air movers and heat sinks is largely driven by the form-factor of the application.  This aspect of IC thermal management is a core mechanical engineering function.

3) Designing optimal cooling solution and choosing best control algorithms would necessitate good understanding of the critical thermal parameters governing the temperature regime of the CPU.  Thermal interface materials which couple the dissipated power to the heat sinks are often the first major roadblock for the heat on the way to environment: its choice is of critical importance.   For high flux density application it's often responsible for the largest share of temperature budget.   This aspect of IC thermal management is also a core mechanical engineering function.

We now want to touch upon what actually determines the temperature limits for the IC design.  While ultimately it's a complicated subject, with the considerations that need to be given to circuit speeds and power draw as well as optimal user experience, the long term IC reliability is the starting point when initiating a mechanical design cycle. (For this blog, we neglect the underlying complexities of semiconductor device physics and materials science engineering.)  Delivering reliably operating system requires coordination of multiple manufacturers in the production chain, from fab to packaging to system.  While earlier manufacturing could be based on case-by-case, supplier-to-supplier interaction, the commonality of material sets and packaging form-factors for most applications led to development of industrial reliability specifications. 

Among these a major challenge for industry is meeting reliability standards in temperature cycled environments.  For IC packaging, the underlying conflict driving these issues is the difference in thermal expansion between the crystalline silicon, the material hosting the enabling circuitry, and the "spatial transformer", the material used for delivering signals from micro- to macro-scale: the package substrate.   These issues came to the forefront to become critical factors in the selection of packaging materials when IBM introduced flip-chip technology as a way of achieving high interconnect density IC packaging.  Initially met with caution (as are most breakthroughs), the tipping point was the introduction of underfill, a material initially intended for electrical insulation between the solder chip-to-package electrical connectors.   While certainly achieving this objective, the underfill with the right mechanical properties protected solder connectors from excessive repeated deformation and eventual failure: anyone who broke a metal wire by bending it multiple times is familiar with the phenomenon.  By addressing this weakness of an early flip-chip technology, mass-production for consumer became possible. 

Writing about this particular issue in an IC thermal management blog isn't a coincidence.  The underfill is often a first material that loses its mechanical stability as temperature increases above a certain point, a glass transition temperature.  Choice of the transition temperature has bearing on stresses in increasingly weak interlevel dielectric materials (needed for high-speed operation), so finding an optimum underfill is a complicated balancing act. 

One famous physicist was fond of saying when faced with a complex problem: "trivialize the issue".  Following his advice, we can narrow down the highest hotspot operating temperature to this parameter, underfill glass transition temperature, or Tg.  For the purposes of IC thermal management, we can think of it as a parameter which collapses all the complexities of thermomechanical interactions in the chip to one identifiable rule: keep temperatures below Tg. 

The engineering consultants at Glew Engineering can assist you with navigating through this and more related issues.  Our mechanical engineers, electrical engineers, and materials science enghineers, have extensive experience it the above described problems and their solutions.

 

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

IC Thermal Management: Part 2, IC Package Heat Spreaders

If you ever thought of upgrading your computer by replacing a CPU, you may have noticed a packet of whiting substance with the processor, sometimes spread out on the heat sink.  The proper operation of the silicon processor, one of the most sophisticated feats of engineering achieved by humankind to date, depends to a large extent on that critical assembly piece, the thermal interface material.  IC thermal management, generally performed by mechanical engineers, is a critical aspect of both consumer products and high performance computing.  Often an engineering team is involved in power management, or IC thermal management.  Sometimes the heat removal is called backend power management to distinguish from the software aspect of the power management.

In general, materials closest to the regions of heat release have the most importance on the IC or transistor operating temperature.  Crystalline silicon has excellent an thermal property, its thermal conductivity being in the same order of magnitude as the materials of which heat sinks are usually made, aluminum or copper.  Silicon crystal has the same structure as diamond, diamond cubic.  This high thermal conductivity of single crystal silicon, in addition to its excellent oxide properties, has helped keep Moore’s Law going strong for close to five decades. 

A seemingly easy task of engineering a heat sink on an IC turns out to be extremely difficult.  The heat flow passes from the IC, through the thermal paste, and must next enter the metallic heat conductor, or heat sink, on its way out to the environment.  This heat transfer involves thermal conduction, or heat transfer through solids.  Usually a fan moves air over the heat sink.  Thus, heat transfer by convection and fluid dynamics comes into play. Convection is the heat transfer through a fluid, either gas or liquid.  Finite element analysis or computational fluid dynamics (CFD) is very useful in analyzing the convective heat transfer to the ambient or room air.   

There are many challenges with both thermal and thermo-mechanical performance: reliability, manufacturability and finally, cost, that enter into the equation.  To highlight one aspect, one must sacrifice thermal conductivity of a thermal interface material sometimes  to the point of reducing its value nearly a hundred-fold compared to the first medium heat flow encounters, silicon.   And this is the second most important material, from a thermal perspective, required for efficient power dissipation.  Packaged thermal heat spreaders were a breakthrough a few years back that decreased the thermal chokepoint by several fold.  However, the addition of a thermal spreader on the chip package requires changes internal to the CPU package and manufacturing process.  What happens internally in the CPU is carefully gauged by their makers to make life easier for the product designers and end users.  Not all CPU form-factors can use the internal heat spreader, and this increasingly is becoming the case, with mobile computing being the preferred consumer choice.

If you decide to explore putting a heat spreader into your package, Glew Engineering can provide the necessary advice and engineering work from our experienced engineers.  We can help with sorting out all the elements in the hierarchy of the heat path out to the environment, so the final product is not subject to pre-mature thermal degradation.  We can also provide innovative suggestions and technical support for heat removal for mobile CPUs, those used in smart phones, tablets and notebook computers. 

Please call us today for a free, no obligation consultation to see how we can help!  1-800-877-5892

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

You've just hired an Engineering Consulting Firm...now what?

Now that your company has agreed to pull the trigger and has secured a third-party engineering consulting firm, now what?  Like everything else you do for your company, you have made this decision based on the bottom line.  Ultimately, you expect to recoup your expenses and come out better off than you would have been if you had elected to do this work in-house. Perhaps you have hired a mechanical engineering consulting firm looking to gain a competitive advantage and get your product to market faster.  It is now up to you to make sure that things go as you hope.

How do you get everything you need from them?  You didn't get to the position you are in today by just hoping that things turn out all right.  You know that you must be a liaison between your company and the engineering consultants.  The more active you are in maximizing the relationship and providing guidance about what you want on the project, the more certain it is that the job will be completed the way you want.

Of course, the first thing you do in any project is plan ahead.  You know what you want the engineering consultants to accomplish, so have it spelled out in a Statement of Work (SOW).  Your SOW is the basic tool that will start you and your engineering consulting firm working together with a clear understanding of what is expected of both of you. You have already discussed many of these terms ahead of time during the hiring process.  However, the SOW will be much more detailed.  It should include:

• A timeline.  This lets the mechanical engineering consulting firm know what key elements of the project you want delivered on what days.  Work with the engineering consultants to establish reasonable goals.  You must balance what you need done with what they are able to do.
• Tasks.  State what tasks must be accomplished in order to meet the goals on the timeline.  Also, state who will complete each task.  Some must be done by the consulting engineers and others by your company.
• Expenses.  Explain who will pay for what.  This includes the costs of materials, sub-contracted labor, and any unexpected expenses.
• The governing process.  Finally, the SOW should outline who is to be in the governing committee, how often it should meet and where.

Be prepared to give the mechanical engineering consulting firm your full support. Ask questions about what access they will need.  Will they be working with any of your employees on a close basis?  If so, take the time to introduce them, and make sure everyone is aware of their position in the relationship and what tasks each member of the blended team is expected to accomplish.

Don't forget status update calls and meetings.  Make sure everyone is meeting deadlines, and find out what is blocking efforts. Remain active in the process from start to finish.  Your engineering consulting firm wants to please you.  They very much want feedback from you about their efforts, just as you want reports from them about their progress.  The more closely you work with them, the more successful both of you will be.

If you still have questions, download our WhitePaper, “The 8 Critical Questions to Ask Before Hiring an Engineering Firm”, or contact us directly.  We look forward to working with you and helping you navigate these issues and solving your companies engineering needs.

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

How to Engage with a Third Party Engineering Firm

Even with each component of a project working, making them work together can stall product development. This costs timeliness meeting market pressures, strategic benchmarks, and contractual deadlines. Engineers solve such problems, balancing literal and conceptual.

Employing a permanent engineering staff proves cost prohibitive for many businesses investing in third party engineering consultants. A good engineering consulting firm offers a diverse range of specialties, without charging you for any service when not needed. For example, electrical engineering consultants can help develop new medical devices from product design all the way to defending that design in court if needed, but neither need burden your payroll for the entire system design life cycle.  Of course, an interdisciplinary engineering team with mechanical engineers, materials scientists, and software engineers  is often needed.  They can be brought to bear on the tasks as needed, without incurring burden and overhead non your company.

Choosing where you contract engineering consulting services can determine success or failure, and good firms want clients aware of this. Glew Engineering Consultants expects potential clients to consider eight different factors before even securing a contract. They provide a link to a whitepaper called, “8 Critical Questions to Ask Before Hiring an Engineering Firm”, for anyone considering third party contracts

Perhaps the most important consideration is the Scope of Work (SOW). Simply contracting with electrical engineering consultants would not meet the SOW demands for manufacturers of a new industrial air conditioning system. That might also involve testing the stress points of Freon tubing for general integrity, safety, and environmental compliance. A third party engineering consulting firm should offer either skill set as needed. If customer abuse of a product causes its failure that leads to expensive lawsuits even when a company lacks valid liability. Then having a firm that can also provide expert court testimony can quickly pay for itself.

So the first step in choosing engineering consultants is eliminating those addressing your SOW too narrowly. Then consider the qualifications of individual engineers on their team. You need both credentials and experience. The best consulting engineers master their own specialty areas as well as understanding how it interacts with others. Passionate about their work, they often hold patents of their own besides those secured for clients.

Once you’ve determined which firms meet your SOW needs and have the most exemplary qualifications, then you should contact them. Only after having discussed your engineering consulting needs with an engineer firm should you apply cost priorities. It takes that dialogue to recognize the true cost benefits of contractors, and to learn what range of pricing flexibility they offer.

For more information on Glew Engineering Consulting visit the Glew Engineering website, blog or call (650) 641-3019.

Linear v Novellus (Semiconductor Equipment)

After 8 long years, Novellus finally rid itself of the lawsuit with Linear Technology. Irell and Manella LLP, for whom Glew Engineering has worked in the past, took no prisoners in the unanimous jury verdict announced yesterday in favor of their client Novellus.  The jury consisted of 12 men and women in Santa Clara, CA, the heart of the silicon valley.  Certainly good news for Novellus' legal team, as well as their bottom line. Congratulation to Jonathan Kagan Esq. and his colleagues.  Now both sides can get back to what they do best - making chips and chip equipment.

Novellus' also shipped their 1000th Vector PECVD tool in February? Considering the tool's throughput and uptime, there may be as many chips out there by now with Novellus' dielectric films as those of any semiconductor equipment manufacturer. See the details at: 

http://ir.novellus.com/releasedetail.cfm?ReleaseID=441840.