Pros and cons of the main application types.

The primary types of coating processes are dip coating, manual spray coating, programmable spray coating, and manual brush application. (Manual brush application will not be discussed here.)

Manual spray coating permits a variety of parts to be coated with minimal process development effort. It is conducted using a handheld spray coating booth that features self-contained material, solvent storage tanks and pumping capabilities, and variable coating pressure and flow rates. Exhaust ports minimize buildup of flammable solvents during the spray process. Exhaust is filtered to prevent coating buildup in the facility exhaust infrastructure. These filters must be changed regularly, as cured coating can build up on the filter material and reduce exhaust flow. The spray booth also contains a turntable to allow the operator to easily rotate the part undergoing coating, while minimizing handling of the uncured coating.

Drawbacks to handheld spray coating are the difficulty in changing material types and the need to mask any areas where coating is not desired. This process does not allow the operator to avoid any areas on the assembly without risking inappropriate variation in applied coating thickness, so areas where coating cannot be applied must be masked. Masking techniques can vary, but the two most common are manually applied tape and mechanical fixturing. Each has its advantages and drawbacks. Manually applied tape has a low material cost, but the application is labor-intensive and can see variation in the areas masked from assembly to assembly. Fixtures are more expensive, but ensure consistent masking. They require regular cleaning of coating buildup and must be revised if significant changes are made to the assembly design.

Changing material types in the handheld spray coating booth requires significant effort to ensure all residual material is purged from the feed lines between the storage tanks and spray gun. Residual material left in the feed lines can result in contamination of the new material, which could inhibit curing of the new material or affect its ability to adhere to the assembly.

A handheld spray coating booth also can be used for manual aerosol spray coating. This commonly occurs when spraying a small quantity of assemblies or where the risk of contamination is high from the coating used in the spray gun. This type of application leverages the advantages of the exhaust and turntable in the spray booth, while avoiding issues related to purging old material from the system. Concerns about masking remain the same across both manual spray processes.

Dip coating is well suited for high-volume applications with minimal coating type changes due to the amount of material required to fill the tank and initiate the process. Dip coaters can come with two separate tanks to permit use of two different materials without the need to remove and discard large quantities of coating.
The equipment permits changes in dip speed, tank dwell time and removal speed.

The biggest disadvantage of a dip coating process is the use of open tanks of material. To reduce the risk from flammable solvent evaporation, we use a nitrogen blanket to inert the area just above the open tank where solvent buildup can occur. A good exhaust system will evacuate any accumulated vapors. Additionally, the pot life of a coating in an open tank is significantly less than the unopened shelf life. This makes dip coating unsuitable for processes where coating is only occasionally performed.

Selective spray coating provides advantages of automating the spray coating process (low process variability, high throughput) without some of the disadvantages of manual spray coating (labor-intensive masking or expensive hard-tooled fixtures). The major disadvantage of automated spray coating is the initial programming required for each application. Once the programming task is completed, the automated process is well suited for high-volume applications regardless of product mix, as well as applications where masking isn’t a viable option.

ACI Technologies Inc. (aciusa.org) is the National Center of Excellence in Electronics Manufacturing, specializing in manufacturing services, IPC standards and manufacturing training, failure analysis and other analytical services. This column appears monthly.

Assessing location and timeliness/repeatability.

I’m sure since my last column readers have all their material volume in control, so let’s move to the two other areas central to a healthy print process: location and timeliness/repeatability.

Proper alignment of the board and stencil are essential for high-yield printing. So, if experiencing problems with location, evaluate the following inputs:

Board and stencil fiducials. When fiducial placement on the board is incorrect, it’s generally an etching issue or a plating issue. With etching, if the board is solder mask defined, it comes down to the quality of how the mask was defined and the technique used. Plating errors generally are more common with HASL boards.

While printers have intelligence and certain tolerances, the more guessing a machine has to do, the more issues with alignment. Likewise, the stencil fiducial quality is critical. Etching the fiducial onto the stencil requires a skilled laser operator and a stencil manufacturing process completely in control, to ensure good fiducial size and shape. Proper stencil cleaning and maintenance are equally important. Over time, paste particles may find their way into the fiducial marks and become welded into the fiducial, making machine centering more challenging. In short, if you give the machine perfect circles on both board and stencil, it will move the stencil to within +/-12.5 μm of where it should be. If you give the system imperfect fiducials, the printer software will guess the perimeter and center, making it more challenging to achieve perfect alignment.

Rail system. Simply put, the printer rail system moves the board in and takes it out. But, if the rail system is set up incorrectly, the board will move. Here’s why:

Operators often overcompensate the board width. As board dimensions may vary slightly, it’s possible that a couple of boards may be slightly bigger than the others, and instead of rejecting them, the operator makes the rail width wider. The boards are flying through, but the large, wide track could also mean you aren’t clamping correctly. The board then moves during the print stroke or the movement of the table, which can cause incorrect deposit location.

Tooling. If using vacuum tooling, ensure the vacuum is in the right place, that it works and is not blocked, so board stability is optimized. In some instances, the milled tooling may have been improperly machined, so the board moves in the tooling plate either during or after the print, which will illicit an alignment error message from the printer.

Calibration and maintenance. For proper performance, maintain and service the printer annually. Calibration is an important component of this maintenance. The vision/alignment calibration is the heart of the machine, really, and should be performed once per year. Shockingly, only about half of all printer owners follow this schedule and at their own peril, I might add. If the alignment isn’t right, you’re wasting your time – especially in the age of miniaturization.

Finally, controlling the print process to achieve high-yield assemblies in a timely, repeatable manner is the last piece of the puzzle. And, while cycle time is an excellent headline figure, there is much more to printing than the cycle time credentials. Let’s take a closer look.

Software. Cycle time evaluates board in/board out speed. While relevant, there is much more to the print process than this, and there are two primary reasons users don’t get the most out of their machine in relation to throughput and cycle time. First, the throughput optimization software still can be difficult to navigate through. Second, there is the tendency to rely on older-generation programs, with adjustments only for board dimensions; thus, any throughput inefficiencies are duplicated. Fortunately, next-generation touch screen software offers intuitive and descriptive selections so that operators can easily find programs and print parameters to ensure maximum throughput.

Setup. In a high-mix environment, being able to change over product quickly also impacts the timeliness of the process. Software certainly plays into this, but so do things like fast changeover of consumables (understencil cleaning paper cassettes, for example) and automatic configurable tooling that helps eliminate setup.

The timeliness and speed of the equipment, however, are only relevant if fast and repeatable. This is where the rubber meets the road, and where machine mechanics aret tantamount. What makes a repeatable system?

Mechanical elements. A printer is, after all, a machine. It has metal, bearings, striker plates and a host of mechanical parts to maintain or replace. The machine has to be repeatable for its lifetime and between service visits. Let’s face it: 12.5 μm of repeatability is just as much about good stability and engineering from the frame all the way up as anything else. And, as we creep toward 300 μm ptich, it becomes critical that printers are aligning and repeatable. Equally important: a credible third-party system to measure against the manufacturing spec.

Alignment repeatability. Dry alignment Cpk is one thing, but running that Cpk in process is quite another. We’re not making alignment machines; we’re making printers, and the actual print stroke, process, and movement of the print head should be included in the alignment repeatability statement.

Clamping system. Having a good and versatile clamping system on board is another factor that impacts repeatability. Some systems permit one clamping system, which is fine when producing only a single kind of board. But most firms need process flexibility and the ability to change clamping systems as the product comes in. And, all the clamping tools have to be equally good and perform well under the influence of the print stroke.

In quite an oversized nutshell, that’s it. There are so many inputs and variables to the printing process, but systematically evaluating all of these on a regular basis will nearly guarantee a robust, healthy print operation. Stay well!

Clive Ashmore is global applied process engineering manager at DEK International (dek.com); cashmore@dek.com. His column appears bimonthly.

Inspired by last month’s column, a designer saves his job.

It’s always good to receive feedback on our columns or articles. After the May issue mailed, I heard via email from a designer (and friend) who read that month’s column, the gist of which lamented the US’s loss of engineering know-how and expertise.

As the writer related, he had been in a situation very similar to the subject of the column. When he learned his position was going to be outsourced, my friend went into proactive mode and decided it was worth fighting for.

I just read the article you wrote. Until about a week ago, I was in a similar situation! I was asked to move to another department, because India has lots of highly educated engineers salivating over the chance to do the kind of work that I do.

Small world, huh?

Anyway, I wanted to let you know that after thinking about the situation for awhile, I sat down and wrote a long letter to my supervisor explaining there is much more to circuit board development than placing components and routing traces. I wanted him to know what he would be losing by casting off a 20+ year veteran in favor of several brand new, gung-ho college grads. Nothing against the fresh up-and-comers – we all had to learn our skills somehow – but while they are busy learning what is a via and what solder mask is for, someone with enough technical experience has to be available to address supplier questions, discuss fab/assembly/test issues, incorporate tools, investigate materials, explore new technologies, improve processes, etc.

It took me several pages to explain what I really do for the company, but after a few days of behind-the-scenes discussions between my supervisor and others, he came back with four words:  “Congratulations, you can stay.”
   
I just wanted to let you know that every now and then, making a case for yourself can pay off.

Of course I was happy for my friend, but mostly I was impressed that he felt that keeping his job was worth the extra effort. I am proud of him for taking the initiative to ensure the decision-makers really understood what they might be losing.

As senior editor, Chelsey Drysdale details in this month's cover story (pp. 62-65) fear of one's job being outsourced lies heavily on the minds of the 400 designers who responded to PCD&F's annual salary survey. I don’t know that it was the case in this instance, but I can’t help but wonder if those who decide to outsource PCB design really understand all the potential ramifications, or whether the decision is made without a thorough examination of all the factors that affect the cost of doing the job. Here in the US, I’ve never heard it said that PCB design is being outsourced because of a lack of local talent. It always seems to be a perceived issue of dollars and cents. And yet, I know of cases where work was sent to India or another country only to find they lost their competitive advantage, and ended up bringing the work back in house.

As my friend says, this is not a personal battle against workers in India or China or the Philippines or wherever. These are some of the oldest and proudest cultures in the world. Their citizens deserve to be proud of their culture and to better lives and standards-of-living.

As someone who has had to make some tough business decisions – especially those that have to do with employees – I know that there are always costs not obvious at first blush. Thankfully, I’ve had people to advise me and help make what I always hope are the right business decisions. As an example, I’ve fielded calls from companies wanting to print our magazines in another country. In many cases the prices for paper, ink and printing are better than our current printer could match. But when we do our due diligence and examine all the costs, including time, quality and shipping, we always find we are better off where we are. And as much as we all love to bash the US postal service, when compared to others in the world, it remains among the best – if not the best – in the world.

The truth is that sometimes outsourcing makes sense. But all things even, or close to it, it does not seem right to add someone to the unemployment rolls by sending that function overseas so that the C-level executives can get a bigger bonus.

For many years, I’ve been telling designers that, unless you are self-employed, you don’t own your job. In the strictest sense, you may feel you have no control over your future. But if you suspect that your employer is about to move your job function, and you really care about trying to save it, take a lesson from my friend and fight for it.

Unless, of course, you don’t really care.

Stay in touch, and we’ll do the same.

Pete Waddell is design technical editor of PCD&F (pcdandf.com); pwaddell@upmediagroup.com.

The nation’s collaborative medical manufacturing template is a prescription for success.

In a visit to Singapore in March, I saw an interesting trend developing. The local government has long marketed the country as a regional hub for sourcing and business investment. It has also done a good job of partnering educational infrastructure with local businesses. And during the economic downturn, it significantly increased the assistance available to companies wishing to improve technology and capabilities. These efforts now have combined for a holistic value proposition that offers combinations of market entry, supplier identification and targeted R&D support.

Singapore’s Medtech Manufacturing Initiative is one example of this focus. Singapore markets itself as Asia Lite: a country with a diverse population and culture. From a business strategy and R&D perspective, this offers some interesting advantages. For example, many US residents think of Asia as a single region. The reality is that Asia is made up of many cultures, races and ethnicities that drive a significant amount of market segmentation.

Take a product as simple as contact lenses. In Asia, there is great variation in eye size and shape. A company wishing to launch a new contact lens product needs to do market testing for the range of variations likely to occur in the countries in which the product will be launched. Part of Singapore’s value proposition is that the country is racially and ethnically diverse enough that much of that testing could be done in a single location.

Similarly, Singapore’s mix of Western and Asian influence provides a legal system based on British Common Law, a population fluent in both English and Mandarin and a business culture comfortable to expatriates from around the world. Recruiting and retaining personnel for multinational operations can be much easier in that environment.

The holistic approach is driven through consortia. For example, the Medtech Manufacturing Consortium is led by the Singapore Institute of Manufacturing Technology (SIMTech), a research institute of the Agency for Science, Technology and Research (A*STAR). This consortium is one of the several it has spearheaded. Its goal is to address the challenges faced by Singapore industry in manufacturing medical devices by establishing a framework to improve or create new medical manufacturing capabilities. It does this by sharing experience, knowledge and best practices in medical manufacturing technology, while facilitating research collaboration among consortium members and research institutes. And the consortium isn’t simply a cluster of suppliers. It is instead a group of suppliers, medical device manufacturers, support service providers, government agencies, associations and universities.

As a result, medical device manufacturers and universities can collaborate in driving manufacturing technology development within the supply base. Some of the participating agencies such as Singapore’s Economic Development Board (EDB) and International Enterprise (IE) Singapore assist medical device manufacturers with market entry strategies that either launch new products and technology or modify existing products to better address regional market needs. In short, Singapore’s value proposition isn’t “locate in this region to find lower labor cost.” Instead, it is “locate in this region for competitive market advantage.”

Not surprisingly, the Medtech Consortium has several electronics manufacturing services members, as well as support service providers aligned with the needs of the electronics industry.  EMS providers include Beyonics Technology and CEI Contract Manufacturing Ltd. Precision engineering suppliers that also perform assembly include First Engineering Ltd., Fischer Tech, and Fong’s Engineering and Manufacturing Pte. Ltd.

Some of the medical OEMs participating include Acme Monaco Asia, BD, Biosensors Interventional Technologies, Cardinal Health, PerkinElmer, SG Molecular Diagnostics and Siemens Medical Instruments.

In addition to traditional manufacturing service providers for plastics, polymers, EMS, precision machining, coating, surface treatment and contract sterilization services, a number of service providers provide services to both OEMs and the manufacturing supply base. These include product development companies, CAD software developers, process control and factory automation system developers, third-party test laboratories, and custom IT platform developers.

The Consortium also offers a fairly focused package of benefits to its members, including technology workshops, competitive intelligence reports, alliance with the Singapore Precision Engineering and Tooling Association and Biomedical Engineering Society, business matchmaking opportunities, focused OEM/supplier partnership projects, a graduate diploma in MedTech manufacturing and a consultancy service that could be tapped for technology roadmapping, device design or feasibility studies, and supply-chain optimization recommendations.

In March, I spoke with several of these suppliers at the Medtech Manufacturing Conference in Singapore. While the Consortium has just been formed, and therefore doesn’t have a lot of concrete success stories to tell, the overall consensus was that its primary value was the networking opportunities it delivered across the entire medtech value chain. Manufacturing suppliers with complex projects could easily tap into service providers or educational resources for support in meeting
customer requirements.

It is increasingly difficult for any company to be successful without strong partnerships. When the combination of pace of technological advancement and global market diversity is added to the mix, the challenge is pretty overwhelming. The MedTech Manufacturing Consortium stands out as one innovative example of ways companies can band to tackle those challenges. 

Susan Mucha is president of Powell-Mucha Consulting Inc. (powell-muchaconsulting.com); smucha@powell-muchaconsulting.com. Her book, Find It. Book It. Grow It. A Robust Process for Account Acquisition in Electronics Manufacturing Services, is available through barnesandnoble.com, amazon.com and the IPC and SMTA bookstores.