7 Cost Reduction Design Tips For Makers

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As a maker, you really need a decent price, with good quality and good service. Contrary to what many people think, you don’t need to look outside of North America for this. You can keep your gaze west of the Atlantic and east of the Pacific.

Like everything else in the modern world, design decisions can have a pretty big impact on your cost. So, let’s take a look at seven design decisions that can make your manufacturing more affordable.

Accept longer lead times. Lead times are one of the biggest factors in electronics manufacturing. Businesses can turn a kitted assembly job overnight, but it costs a lot of money to do that. When you can, a 20-day turnaround that is much more affordable. Accepting longer lead times on PCB fab will drop your cost as well.

Avoid leadless packages Like QFNs and BGAs. Screaming Circuits builds tons of QFN and BGA boards, even down to 0.3 mm pitch micro-BGAs. That’s great if you need those packages. However, since all of the leads are underneath, we have to x-ray every part. That adds a bit of cost to the process. If you can, stick with TSSOPs and other parts with visible leads.

Use reels and continuous strips. To save costs, use full or partial reels or continuous strips of at least 12″ long.

Stick with surface mount. These days, through-hole components tend to be hand soldered. That costs more than machine assembly, so use surface mount wherever possible. Surface mount components tend to be less expensive than through-hole, too. If you do need a few through-hole parts, this is an opportunity to put in a little sweat equity by soldering the through-hole yourself and save a bit of money.

Keep surface mount parts on one side. Putting surface mount parts on both sides of the PCB is a great way to better utilize space. However, if cost is more of a concern, and you only have a few parts to put on the back side, it may be more cost effective to move them to the top side. If you’ve got a lot of parts, the additional cost for assembling both sides may be less than the cost for the extra board size, but with a small number of parts that’s probably not the case. Quote it both ways and see which is less expensive.

Panelize small boards. Sticking with a larger size makes the job easier, and, again, creates extra savings. If your board is smaller than 16 sq. in., panelize it.

Save on start-up costs. Just the act of starting out can pretty much break the bank. Software like PCB123 offers full-featured PCB CAD systems you can get free of cost.

By following these guidelines, you can get a decent price and quality service.

Duane Benson 

 

Straightforward Explanation of MIL-I-46058C for Conformal Coatings

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During your selection of conformal coating you ran in to a specification that you have seen before but not fully understood.  Conformal coating choices are vast, but with so many available, how does a user pick the correct one? Are there minimum standards that define what a conformal coating is supposed to do? Thankfully, yes there are. This column will focus on one such standard: MIL-I-46058C.

The official title for the specification is MIL-I-46058C, “Insulating Compound (For Coating Printed Circuit Assemblies).” The standard serves as a material standard, used to evaluate and document that a particular coating meets a list of specific performance attributes (more on those later). MIL-I-46058C was developed to define a uniform set of test methods and performance requirements for conformal coatings and gives users confidence that the material they select will perform.

MIL-I-46058C is managed by the Defense Logistics Agency (DLA).

DLA manages the standard and maintains the associated Qualified Products List (QPL). For a coating to be placed on (and stay on) the QPL, it must be tested annually by a DLA-certified laboratory. The data are reviewed annually by DLA to ensure that each coating proposed for inclusion on the QPL still meets the requirements of the standard. The latest version of the Qualified Products List is available from www.dscc.dla.mil.

MIL-I-46058C evaluates conformal coatings to an extensive list of properties. The tests are:

  1. Curing time and temperature: Coating must meet the requirements of the standard when cured according to the manufacturer’s instructions.
  2. Appearance: When cured per manufacturer’s instructions, coating should be smooth, homogenous, transparent, free of bubbles, pinholes, etc.
  3. Coating thickness: The recommended coating thickness shall be 1-3 mils for acrylic, urethane and epoxy coatings; 2-8 mils for silicone coatings; 0.5-0.7 mils for parylene coatings.
  4. Fungus resistance: The coating cannot support the growth of fungus.
  5. Insulation resistance: The average insulation resistance of all coated specimens shall be a minimum of 2.5 x 1012 ohms, with no specimens having a measured value below 1.5 x 1012 ohms.
  6. Dielectric withstanding voltage (DWV): Coated specimens subjected to 1500 VAC for 1 minute shall exhibit no disruptive electrical discharge (spark over, flashover or breakdown). The measured leakage current shall not exceed 10 microamperes.
  7. Q (Resonance): The resonance values for the coating, measured before and after immersion in DI water, must not change beyond specified limits.
  8. Thermal shock: Coating materials are subjected to 50 cycles of thermal shock. After thermal shock, coating must meet the Appearance and DWV requirements.
  9. Moisture resistance: The insulation resistance of the coating is measured under high temperature and humidity and must meet minimum specified values. After temperature / humidity exposure, the coating must meet the appearance, insulation resistance and DWV requirements.
  10. Flexibility: Coating is applied to a test substrate, cured per manufacturer’s instructions and bent 180° over a 0.0125” diameter mandrel. There shall be no evidence of cracking, crazing or adhesion loss of the coating.
  11. Hydrolytic stability: Coated specimens are subjected to four 28-day exposure of 85°C / 90% RH. After this exposure, the coating can show no evidence of softening, chalking, blistering, cracking, tackiness, adhesion loss or reversion to liquid state. The coating must also remain transparent enough to view nomenclature and color codes used to identify the components over which the coating is applied.
  12. Flame resistance: Coating shall be self-extinguishing and non-burning when subjected to a flame test.
  13. Shelf life: Coating must meet appearance, insulation resistance and DWV when tested after storage for six months at 25°C.

MIL-I-46058C was declared “inactive” in November 1998. This deactivation meant the standard was “inactive for new designs, except for replacement purposes.” This certainly does not mean MIL-I-46058C disappeared from the landscape. Today, MIL-I-46058C persists for coating users and specifiers due to its requirement for independent third party certification and remains the only published conformal coating standard with an associated QPL.

Caution!  As a user you have many choices of conformal coatings. Many materials claim to “meet the requirements’”of MIL-I-46058C. These are coatings have probably not been fully tested to the rigorous standard required to obtain and maintain MIL-I-46058C qualification. Treat these coatings with caution: “meets” does not mean “is” on the QPL. There is only one way to verify this and that’s through the DLA website.

The conformal coating selection process involves a check list of many variables. One of these variables is the need for MIL-I-46058C qualified coating. We hope that this article helps you understand not only how to find such a coating, but also what is behind this qualification.

Jeff Sargeant
www.humiseal.com

As We Were Saying

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And in today’s headlines from India:

  • “Foxconn Likely to Shy Away from $5 bn Investment in Maharashtra“: “Although the world’s largest contract electronics manufacturer — which makes Apple’s iPhone and iPad — had entered into a pact with the state government in August last year, the company is yet to start its production unit in the ‘absence’ of customers.”

As we were saying …

Simple Recipe to Avoid Conformal Coating Blush

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Your conformal coating film is supposed to be clear and transparent, but it’s cloudy-white and dull … it’s blushing. This condition is an indication that your coating film is trying to tell you something, and it isn’t that it’s embarrassed.  This blog will help you better understand why your conformal coating film is blushing from acquired moisture contamination and help you eliminate this defect.

Coatings appear cloudy because they have inadvertently acquired moisture, either due to their hygroscopic nature or by artificial means (a cooling mechanism created by solvent evaporation), which then reacts negatively with the coating resin –  exhibiting itself as a milky, colloidal-type substance.  Many different types of conformal coating chemistries can be sensitive to blushing under certain circumstances.  These circumstances are usually related to specific ambient conditions, application, cure, condition of the assembly/substrate/associated components, storage environment and/or equipment under use.

These conditions include:

  • High humidity, ~70% or higher
  • Low (or cooling) temperatures, ~16oC or below
  • Assemblies and associated components exposed to ambient moisture during storage prior to coating, can significantly increases the chance of blushing.  To overcome this, baking is often recommended. Not baking your boards after cleaning is a prime source of moisture uptake into assemblies
  • Storage conditions (opened containers, inside pressure pot, RH resident in the charging gas of the application equipment) and interaction with moisture already on the assembly.

In conjunction with this variety of circumstances, certain solvent-borne chemistries can aggravate this condition due to the fast evaporation of internal solvents.  This creates a cooling mechanism as they volatize from the film.  This cooling mechanism will condense any moisture vapor that may be present in the immediate atmospheric area.

High solids, low volatile room temperature vulcanized, or UV conformal coatings (with secondary moisture cure functionality) may also show some degree of “blush.” They are more sensitive, possibly hygroscopic, to the presence of ambient moisture vapor as this is utilized to activate their primary or secondary curing mechanisms.

Problems that can be created due to moisture vapor intrusion/blushing:

  • Surface tackiness/incomplete cure
  • Below standard aesthetic quality
    • Coating discoloration
    • Poor gloss retention
  • Poor adhesion
  • Wrinkling during second coat application/over-coating.

Here are some simple steps to start with … DIY:

  • Maintain nominal ambient humidity in the production environment between 45% and 65%.
  • Maintain nominal ambient temperature in the production environment between 18oC and 27o
  • Increasing the flash time between coating application and cure may help, as moisture vapor in the wet film may have the potential to re-evaporate
  • Use different thinner to change evaporation rate.
  • Use desiccated air/nitrogen to push coating through applicator
  • Post-bake assemblies after aqueous wash (if applicable) to eliminate any entrapped (under or between components) moisture.
  • Ensure that all partial containers are properly sealed when stored. Nitrogen purge in partially used container helps to eliminate moisture.

We hope that this helped you understand what blushing is, how it occurs, and how to prevent/alleviate it from occurring.  Remember that moisture is the root cause of cloudy or blushing conformal coating.  With many potential sources of moisture contamination, following our simple recipe will lead you back to a crisp, clear, and transparent film, and zero defects.

Nick Naumovic

www.humiseal.com

Fab Drawings or Assembly Drawing Standards?

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It’s not always possible to have all of the information needed for a successful PCB assembly printed on the blank PC board. When this is the case, we ask for an assembly drawing – like I suggest here. But what about things that are important at the PCB fabrication stage rather than at assembly.

That’s where the fab drawing comes in.

One of the problems with this system is that the “standards” for fab and assembly drawings are only loosely adhered to, if you can call them standards at all. If in doubt, label the fab drawing “Fab drawing” and the assembly drawing, “Assembly drawing.” That may seem obvious, but in the wide world of technology, obvious too often is anything but.

(image from xkcd.com)

Clearly label anything that the fab shop needs that isn’t obvious from the Gerber files, make a PDF, and label it “Fab drawing.pdf.” Do the same for any assembly information and instructions and label it “Assembly drawing.pdf.” If information is needed by both the fab shop and us, the assembler, put it in both drawings.

We recently had a case where a component polarity wasn’t marked on the board or in the assembly drawing, but was in the fab drawing. We do our best to catch such things, but it ads a bit of ambiguity to the process. If you’ve been reading this blog before, you’ve likely picked up that I do not like ambiguity. I do not like it one bit.

Duane Benson
Vote for clarity! Kick ambiguity out to the street

http://blog.screamingcircuits.com

Filipino Fiasco

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The situation in the Philippines is starting to feel a lot like that of Turkey from July of this year: A paranoid leader turned strongman seeks to exert his supreme dominance over a democratic nation.

Will the country stand back while Philippines President Rodrigo Duterte effectively declares martial law? Or will the army — no fan of China — assert itself and ironically return law and order to the nation by overthrowing a budding dictator?

There are more than 30 EMS companies in the Philippines, the largest of which include IMI, ranked 28th worldwide in EMS revenue at $800 million last year, EMS Components Assembly ($110 million), and Ionics ($63 million), which has seven plants there.

Other major players with smaller operations include Siix, Celestica, Cal-Comp and Wistron.

Although US-centric for decades, the Philippines under Duterte are pivoting toward China. US companies have invested nearly $5 billion in the country; even if they no longer feel welcome, extracting that won’t be easy.

Either way, politically the Philippines are a complete mess. Duterte has taken a stable nation and completely disrupted it, without any clear end-game. If his goal was to expand his nation’s markets and hedge its bets — understandable, given their neighborhood — he could have done so in a much simpler fashion. As it stands, he has alienated many of the Philippines primary trading partners, and for what? Business partnerships don’t have to be a zero-sum game. He could have ramped his dealings with Beijing without destroying his relationship with Washington.

Duterte likes to rail against the West for being what he considers corrupt and hypocritical would-be overlords. His own military very well appreciate the security the West historically has provided, however. His words might play well with the public, but he could very well pay the price with his life.

 

Full Autonomous Autos: Decades Away and In Need of Unprecendented Reliability

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Folks,

Since writing my last blog post, there continues an unending litany of articles about the imminent arrival of the self-driving car. I stand by my position that a fully functional self-driving car is decades away. Let me discuss why.

I was recently asked about Google’s efforts amide claims of tens of thousands of hours of self-driving.  Wikipedia has the best answer:

As of August 28, 2014, according to Computer World Google’s self-driving cars were in fact unable to use about 99% of US roads.[51] As of the same date, the latest prototype had not been tested in heavy rain or snow due to safety concerns.[52] Because the cars rely primarily on pre-programmed route data, they do not obey temporary traffic lights and, in some situations, revert to a slower “extra cautious” mode in complex unmapped intersections. The vehicle has difficulty identifying when objects, such as trash and light debris, are harmless, causing the vehicle to veer unnecessarily. Additionally, the LIDAR technology cannot spot some potholes or discern when humans, such as a police officer, are signaling the car to stop.[53] Google projects having these issues fixed by 2020.[54]

Ford claims it will have self-driving cars deployed by 2020. However, a quote by Jim McBride, Ford technical lead, sheds some light:

“Q: What are the big technical challenges you are facing?

“A: When you do a program like this, which is specifically aimed at what people like to call ‘level four’ or fully autonomous, there are a large number of scenarios that you have to be able to test for. Part of the challenge is to understand what we don’t know. Think through your entire lifetime of driving experiences and I’m sure there are a few bizarre things that have happened. They don’t happen very frequently but they do.”

Level four is indeed impressive, but it is not full autonomous as described by SAE:

SAE automated vehicle classifications:

Level 0: Automated system has no vehicle control, but may issue warnings.

Level 1: Driver must be ready to take control at any time. Automated system may include features such as Adaptive Cruise Control (ACC), Parking Assistance with automated steering, and Lane Keeping Assistance (LKA) Type II in any combination.

Level 2: The driver is obliged to detect objects and events and respond if the automated system fails to respond properly. The automated system executes accelerating, braking, and steering. The automated system can deactivate immediately upon takeover by the driver.

Level 3: Within known, limited environments (such as freeways), the driver can safely turn their attention away from driving tasks.

Level 4: The automated system can control the vehicle in all but a few environments such as severe weather. The driver must enable the automated system only when it is safe to do so. When enabled, driver attention is not required.

Level 5: Other than setting the destination and starting the system, no human intervention is required. The automatic system can drive to any location where it is legal to drive.”

The difference between level 4 and 5 is enormous.  Just a few days ago I drove a level 2 Volvo SC90. It was a lot of fun. It had autonomous steering and acceleration/breaking. It worked very well, but it needed the lane markers, a not insignificant requirement.

Level 4 could not take you on a trip from my house, in Woodstock, VT, to a meeting in downtown Boston. To start, some of the trip is on roads without lane markers. Let’s also assume that there is construction with hand written signs directing the cars to a detour. There is also a traffic cop who signals you to stop and roll down the window to listen to instructions, a huge pot hole that has a hand-made warning sign is in downtown Boston, etc. None of these challenges would be unusual for a human, but a challenge for Level 4 autonomy.

Ford’s self-driving car has the equivalent of 5 laptop computers.

 

Singapore has implemented what appears to be level 3 vehicles, but there is a human backup and the route is specially selected.

All of this is exciting news.  But getting a vehicle that can handle 99% of human driving tasks with 99.99% reliability (let’s call it Phase I) will be easier that getting the last 1% with 99.99999% reliability (Phase II).  I agree that Phase I may be only years away, but Phase II is decades away.  Without Phase II, the driverless car that has no steering wheel or gas pedal is not achievable.

How does all of this affect us in electronics assembly?   It will be an interesting adventure to work with the auto industry on the extreme reliability required.  My guess is that this reliability need will be a dominant theme in the future.

Note: Probably the best article on this topic was in the June 2016 issue of Scientific American.

Cheers,

Dr. Ron

 

Self-Driving Vehicles Will Require Unprecedented Reliability

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Google’s self-driving car

Autonomous (driverless or self-driving) cars will require unprecedented software and hardware reliability. This need may require double or triple redundancies in some critical systems. Those of us in electronics assembly think first of the reliability issues with hardware, but software concerns may be even greater.  Almost every day we have to reboot one of our electronic devices to get it working, due to software issues, yet seldom have a hardware fail. So the equivalent of the “blue screen of death,” may be the greatest concern for this future technology.

Still, hardware reliability will be a critical issue. Therefore we can expect our colleagues in automotive electronics assembly to be the most demanding in history regarding reliability.

Just how far in the future is the autonomous automobile? Some may think it is already here after reading about the auto accident death of a man while his Tesla was doing the driving.  However, this accident was caused by an auto with only the L2 capability of automation. In L2 automation only speed and lane changing is performed by the auto and only in special circumstances. The human is still in control.

The industry has defined 5 levels of automation, as shown in Figure 1 below. Only L4 or L5 is true automation. In L5, the auto would likely not have a steering wheel, as the human does not take part in driving at all. Figure 1 came from a recent article in Scientific American by Steven Shladover. Shladover argues that L4 and L5 vehicles are decades away, at the earliest 2045. Informal discussions I have had with a leader in the industry, who does not want to be quoted, agrees with this perspective.

 

Figure 1. Many technologists suggest that only L4 or L5 automation is practical.

 

 

 

 

 

 

 

 

 

 

 

 

 

Many argue that it makes no sense to have L2 and L3 vehicles as the driver could lose focus while the auto is driven autonomously, and not be alert when needed. When the L4-/L5-era arises it will likely reduce the death toll from accidents significantly. When one considers that 100 people in the US are killed each day in auto accidents, this benefit will be welcome indeed.

Fully autonomous cars will be a major technology disruption. According to John Krafix, CEO of the Google Self-Driving Car Project, we use our cars only 4% of the time. In the era of driverless cars, why have the expense of owning one, when you can summon one for a much lower yearly cost?

It will be interesting to watch all of this unfold, and it will present new and rewarding challenges to those of us in electronics assembly. However, sadly, most of us working today will be well past retirement by the time it comes to full fruition.

 

Racing to Failure?

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Reuters is reporting that Samsung has temporarily suspended production of the Galaxy Note 7 smartphone after replacements for the first batch of devices also proved to be almost as good at spontaneously combusting as they are at surfing the Web.

One brand manager went so far as to compare the self-igniting smartphones to the Ford Pinto, whose rear-end fuel tanks had the unfortunate tendency to explode upon contact.

Samsung’s situation isn’t unique: Apple experienced similar problems with previous iterations of the iPhone. But given the speed with which new phone models are brought to market, one begins to wonder whether these defects are part of a larger failure of the process itself.

Is is possible we’ve reached an inflection point whereby, in the rush to get product to market, the validation phase is — pardon the pun — being short-circuited? Are suppliers properly vetted, product thoroughly tested, risks appropriately balanced?

Or has consumer electronics reached a point where it’s a race not to market but to failure?

Oct. 11 addendum: The Korea Herald and others are now reporting Samsung has decided to pull the plug completely on the Note 7. The estimated cost: Billions.