Análise de solda em placas de circuito impresso

Análise de solda em placas de circuito impresso from Marcelo Chirai

Collaborative Robots

From: Karine Simard [mailto:k.simard@robotiq.com]
Sent: sexta-feira, 20 de novembro de 2015 09:09
To: Marcelo Chirai
Subject: What can collaborative robots do? 5-step practical guide to getting started with collaborative robots

Let's explore the possibilities of collaborative robots. This will be useful when we start looking for cells with automation potential.

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Step 1: What can collaborative robots do? In this chapter, we’ll explore the possibilities provided by collaborative robots. This will be useful when we start looking around the factory floor for places with automation potential. Although collaborative robots are a new technology, this does not mean that they are necessarily complex. In fact, it’s the complete opposite. While traditional robots have evolved to satisfy the need for high volume industries, collaborative robots have been designed for the challenges of high mix manufacturing found in all SMEs. Just like traditional robots, collaborative robots can: Move parts around Follow a path to perform a process Work autonomously for extended periods of time, increasing productivity and quality But unlike traditional industrial robots, collaborative robots: Are simple and fast to program by non-experts. Think - half a day of onsite training, compared to 2-days of offsite classes for industrial robots. Have a small footprint. Most applications don't require fencing. Are simple to integrate for the simple tasks. These are the tasks you should start with. Can be repurposed easily for new tasks. The bottom line is that with collaborative robots it is possible to do the same tasks that you would do with industrial robots, but with a smaller, less risky investment and a greater flexibility.   Typical Applications Here are a couple of examples of what can be done using collaborative robots: Machine Tending: Placing a part in a machine for processing. The robot can load and unload the part, hence freeing the operator from this redundant task. Pick-and-place: Moving a part from the output of one process to the input of the next. For example, grabbing parts from a bin and ordering them on a tray. Here again, this is a non-value added task that frees the operator. Lightweight applications: Most applications that can be done by a human without requiring dexterity can be done by a collaborative robot. A great application for full human-robot collaboration is where the robot is moving the part and the operator is using his/her dexterity to assemble the part.   However, before going hog wild and buying just any robot, you need to know which applications are best suited for automation. Get the PDF version for this step here.   What's next: Here are the upcoming chapters in our 5-step practical guide: Week 2: Identify potential processes or tasks for automation. Week 3: Get the team on board with robots. Week 4: Assess your potential applications. Week 5: Get management on board with robots.  We hope you find this series useful in getting your first robotics cell in your factory. Want to discuss your challenge? Request a consultation with our robotics applications experts.

Robotiq   966, chemin Olivier, Suite 325    St-Nicolas,  QC      Canada You received this email because you are subscribed to Getting Started with Collaborative Robots: a 5-Part Practical Guide from Robotiq.

ESD Grounding - 1 Meg Ohm Resistor

October 23, 2015

 

Why do we need to use a 1 meg-ohm resister for ESD grounding?

R.R.

Experts Comments

This is a good question. A 1 megohm resistor allows any static charge, whether from the bench through the product and then through the grounded person or operator or vice-versa, to discharge completely over time, typically less than 1 second. Without the 1-meg resistance, the static discharge would be an instantaneous drain directly to ground through the product. Let's take the case of a highly charged operator who is not wearing any dissipative footwear and is not grounded with a wrist strap as an example: If the ESD mat or a conductive metal surface that the sensitive circuit card assembly (CCA) is resting on is grounded with just an electrical wire connection directly to ground, there is nothing to slow down the discharge of the operator through the CCA and through the conductive mat to ground. The CCA takes the full brunt of the electrical discharge (the ESD event) instantaneously, and that instantaneous discharge is what can damage the components on the CCA. If a 1-megohm resistor is in series with that wire, the charge bleeds off over a few milliseconds and this reduces the shock to the CCA. ESD wrist straps typically have a 1-meg resistor built into them. This is to protect against a highly charged mat or ungrounded surface from discharging instantaneously through the CCA and then through the operator to the ground connection that the wrist strap is plugged in to. Foot straps and ESD shoes are designed to be dissipative in this manner also. ESD floors are dissipative, mats are dissipative, ESD tools are dissipative, all of these things work to allow built up electrical charges to accomplish equilibrium (no difference of electrical potential) within a few milliseconds, but never instantaneously. Engineering is nothing more than the management of forces trying to reach equilibrium, whether it is temperature, gas, chemistry, electrical or fluid forces. It does not work for spiritual or political forces, however. Those defy logical or scientific reaction. So may the Force be with you.

Richard D. Stadem Advanced Engineer/Scientist General Dynamics Richard D. Stadem is an advanced engineer/scientist for General Dynamics and is also a consulting engineer for other companies. He has 38 years of engineering experience having worked for Honeywell, ADC, Pemstar (now Benchmark), Analog Technologies, and General Dynamics.

The short answer to your question is, "For operator safety". Think about it... what is the purpose of the grounding strap? It's to provide a path to ground for electrical energy. The problem is that we work around sources of electricity all the time in the electronics industry. If an operator had just a plain wire from his or her wrist the operator would definitely be grounded for ESD purposes. However, he or she would also be grounded if that person comes across a bare wire carrying 110V or, in many cases 220V or more. In those cases, the wrist strap would go from a simple relief of ESD to a potential life threatening ground. The electrical energy, the full force of the 110, 220 or more is now coursing through the operator's body with an easy path to ground. A typical household electrical circuit may have 15 to 20 amps of current. As little as 0.25amps traveling across a person's chest can cause a potentially lethal heart condition. By placing the 1 meg ohm resistor in the grounding wire the operator is protected from electrical shock, injury, or even death.

Kris Roberson Manager of Assembly Technology IPC Kris Roberson has experience as a machine operator, machine and engineering technician and process engineer for companies including Motorola, and US Robotics. Kris is certified as an Master Instructor in IPC-7711 / 7721, IPC A-610 and IPC J-STD 001.

To prevent the user from being electrocuted should their wrist strap come into contact with a live mains voltage. 1 meg Ohm is more than enough to carry ESD potentials safely to earth and protect the user as well.

Paul Austen Senior Project Engineer Electronic Controls Design Inc Paul been with Electronic Controls Design Inc. (ECD) in Milwaukie, Oregon for over 34 years as a Senior Project Engineer. He has seen and worked with the electronic manufacturing industry from many points of view, including: technician, designer, manufacture, and customer. His focus has been the design and application of thermal process measurement tools used to improve manufacturing processes like: mass reflow and wave soldering, bread baking, paint and powder curing, metal heat treatment and more.

To prevent the electrostatic charge build-up for ESD protection, everything which can acquire a charge is grounded including people working there. The workers use conductive shoes and a grounded band on their wrist to keep themselves grounded. However, if someone is well grounded and touch something with some high voltage on it, they can easily get a very large and dangerous electrical shock. To prevent this, people working in this kind of environment are not directly grounded but through a resistor which limits the current flowing through them to safe value. Generally this current limiting is done using 1megaohm resistor in the grounding wire. This 1 megohm resistor limits the current to much less than 1mA, if someone accidentally touch a wire with mains potential (230V).

Santosh Kumar R&D Manager MK Electron Co. Ltd Santosh Kumar is R&D Manager at the MK Electron Co. Ltd., Korea and engaged in the electronic interconnect materials development and technical marketing. His key focus is novel lead-free solder materials, electronics packaging, wire bonding materials and process.

The 1-megohm resistance is used for two reasons: It limits the speed that charge is passed, avoiding rapid discharge of an item, which is one way to induce ESD damage to the item (the other being a rapid discharge from a charged object to the item) It provides for operator safety by limiting current in the event that the wearer of a grounding device comes in contact with high voltage.

Fritz Byle Process Engineer Astronautics Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.

A resistor is used as a safety precaution. Since electrical equipment is also connected to ground ... (some companies do not have a separate electrical ground from their ESD ground) there is a chance that electrical equipment could short-back into the electrical ground and thereby transmit large currents into the ESD straps of individuals. That could be catastrophic. Follow the EOS/ESD standards and all will be good. Note that the grounding of racks and equipment needs to be checked with a resistance meter as well. You want the equipment and work surfaces to have "single point grounding" ... this means that the feet of the equipment should be electrically isolated from conductive floors. Otherwise, the effective resistance of parallel circuits follows this formula ...1/Rt = 1/R1 + 1/R2 + 1/R3 + ...   I can explain in more detail is you wish to contact me directly.

Rick Perkins Chemical Engineer / Owner Chemical Logic Inc. Rick Perkins is a chemical engineer with more than 25 years of Materials & Processes experience. He has worked with Honeywell Aerospace in high-reliability manufacturing, as well as with several oil-field manufacturing companies. He also has a good understanding of environmental, health, and safety regulations.

The resistor is a safety feature to limit the current in the event the operator touches an energized conductor. A 1 meg-ohm resistor is typically used for protection from normal mains supplies of 110 to 220 VAC.

Richard Henrick Quality Assurance/Regulatory Compliance Manager Sanmina Corporation Richard has 18 years experience in the medical electronics industry at both a contract manufacturer and OEM. His experience includes PWA and finished device manufacturing as a Manufacturing Engineer and during the past 7 years as plant Quality Assurance/Regulatory Compliance Manager. He holds 5 American Society for Quality Certifications and is a Certified IPC 610 Trainer.

A high resistance, such as 1 MΩ, is used to discharge static slowly.  Discharging static electricity quickly results in a spark and a spark at or near the source of discharge is results in electrostatic overstress (damaging high voltage) to ICs and sensitive circuitry. Grounding sensitive equipment or personnel through a 1 MΩ resistor is a universally accepted practice and prescribed in a variety of ESD standards.

Gary Freedman President Colab Engineering A thirty year veteran of electronics assembly with major OEMs including Digital Equipment Corp., Compaq and Hewlett-Packard. President of Colab Engineering, LLC; a consulting agency specializing in electronics manufacturing, root-cause analysis and manufacturing improvement. Holder of six U.S. process patents. Authored several sections and chapters on circuit assembly for industry handbooks. Wrote a treatise on laser soldering for Laser Institute of America's LIA Handbook of Laser Materials Processing. Diverse background includes significant stints and contributions in electrochemistry, photovoltaics, silicon crystal growth and laser processing prior to entering the world of PCAs. Member of SMTA. Member of the Technical Journal Committee of the Surface Mount Technology Association.

simply to protect the personnel from being electrocuted in event any electrical equipment on conductive table top gets short circuited. The current in case of short circuit takes shortest resistance path, one meg makes circuit through human body more resistive, thereby preventing persons being electrocuted. For ESD precaution, it is essential to hold equipment, personnel and ESD assemblies grounded at same potential.

KN Murli Head-Quality Astra Microwave Products, Hyderabad, AP India Holds Degree in Engineering, started off as Scientist/Engineer in ISRO (Indian Space Research Organization) in Quality Assurance of Space hardware Electronics Production. Worked in the area of Parts, Material and Process; DPA, FA and Process Qualification for space and ground hardware. Later moved into Private sector and worked in the area of Quality Management Systems & ISO 9001 certification. Currently hold a position as Head-Quality in RF/Microwave Product manufacturing for Defense and Aerospace segment.

The resistor protects the operator from becoming the path to ground in the event there is contact with live voltages. Have you gained access & downloaded the current EOS/ESD ST 20.20? The use of a 1 meg ohm resistor has been a part of EOS/ESD safety for at least 25 years. I recommend that you familiarize yourself with the standards that have been implemented for years. I have no idea what country you are located in but the usage of 1 meg ohm protection is the norm in any quality wrist strap sold currently on the market.

Jerry Karp President JSK Associates Based in. Northern California since 1971. Founded JSK Associates in 1979. Actively involved in soldering, cleaning, chemistries. 30 years experience in EOS/ESD control.

Reader Comment If the question is about wrist straps, no question it requires 1M resistor (for the dual wristsraps two 1M resistors in each half). Regarding reducing strength of discharge, lets stress-test this theory - what if this resistor is 10M? 100M? 1G?  What about the proverbial doorknob that has infinite impedance to ground,yet one can be zapped on contact by walking on the carpet? As evident, the theory of 1M resistor used to "slow down" or reduce discharge strength doesn't hold proverbial water. Metal objects, i.e. workbenches and others, have capacitance to ground, big or small. Charged metal object coming into galvanic contact with such workbench or other conductor, grounded or not, would rapidly equalize voltage between the two objects whether any resistor at all is present anywhere. If you want to reduce discharge current on contact, reduce metal-to-metal contact (dissipative tweezers come to mind) or assure that the contacting objects have the same voltage, preferably both equal to ground. This is the entire purpose of grounding workbenches and other metal objects. 1M resistor performs no utility in reducing discharge strength but it does increase possibility of induced voltage on the objects from radiated sources such as fluorescent lights, power lines, operation of tools and such. Vladimir Kraz, OnFILTER, USA

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Eletrostática from Marcelo Chirai

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ABC do Osciloscópio from Marcelo Chirai

Rugged computing terminology and standards

 

Rugged computing terminology and standards
(by Conrad H. Blickenstorfer)

What's an IP rating? Ingress Protection? How is that measured, and what does it mean? What does "intrinsically safe" mean? How do they do drop tests and such? Where can you find information on testing procedures? What are NEMA ratings? What does RoHS mean, and is it important? (Yes, especially if you deal with European markets). And what's FIPS 201? Or does a client request adherence to IEC 60601? Or what does a vendor need to do to comply with MIL-L-85762A for night vision imaging systems?

All of these terms, and more, you'll encounter in this specifications and sales pitches of rugged computing equipment. Knowledge of what it all means is crucial to understanding the potential suitability of equipment for your applications, and also when discussing your needs with a vendor.

In this section you'll find explanations of the many definitions and terms used in rugged computing, and also information on the various rating systems employed to indicate ruggedness, sealing and other environmental protection. You'll also find descriptions and updates on enabling technologies, such as outdoor-readable notebook computers screens.

You also find primers of a variety of ancillary technologies, such as RFID, bar code scanning, and others. What you see now is just the beginning. Over time we'll be adding additional definitions, primers, and white papers.

Vendors: If you have Technology White Papers which you'd like to share with potential clients, please email us at cb@pencomputing.com.

At RuggedPCReview.com we consider the Ingress Protection rating to be especially important. It is in the IEC (International Electro technical Commission) 60529 international standard and classifies how well electrical enclosures are protected against intrusion of solid objects, dust, and water. When used to indicate sealing of rugged computers, the IP rating tells you whether dust or water can get into your computer. Below is the IP rating table.

IP (Ingress Protection) Rating Table

	SOLIDS (1st number)		LIQUIDS (2nd number)
0	No protection	0	No protection
1	Protected against objects > 50mm (hands)	1	Protection against dripping water or condensation
2	Protected against objects > 12mm (fingers)	2	Protection against water spray 15 degree from vertical
3	Protected against objects > 2.5mm (tools/wires)	3	Protection against water spray 60 degree from vertical
4	Protected against objects > 1mm (small tools)	4	Protection against water spray from all directions
5	Protected against dust, limited ingress	5	Protection against low pressure jets of water
6	Totally protected against dust	6	Protected against heavy seas
7	N/A	7	Protection against the effects of immersion (6 inches to 3.3 feet)
8	N/A	8	Protected against continuous immersion (but under conditions defined by the manufacturer)

What is the MIL-STD-810F

It is an equipment testing standard by the United States Department of defense. It describes in detail testing procedures designed to determine how equipment holds up under a variety of conditions the equipment may encounter while being used, transported and stored. These conditions include temperature, impact, vibration, humidity, and more. Note that while the standard is extensively used for testing of rugged computing equipment, it was not specifically designed for that type of equipment. As a result, some tests are ambiguous when applied to computing equipment.

What is the difference between MIL-STD-810F and MIL-STD-810G?

MIL-STD-810F was introduced on January 1, 2000. MIL-STD-810G was introduced October 31, 2008, and supersedes MIL-STD-810F. The two documents are not substantially different, but different enough so that many testing procedures have different articles and numbers. As of late 2011, most rugged manufacturers have switched to providing ruggedness testing information using MIL-STD-810G, but some still cite the older standard.

What's MIL-STD-810F Method 506.4 (Rain)?

Manufacturers often refer to MIL-STD-810F Method 506.4. The MIL-STD-810F is a Department of Defense document that describes test methods for environmental engineering considerations and lab tests in great detail (Note that MIL-STD-810G, issued October, 2008, has superseded MIL-STD-810F). Method 506.4 describes testing to determine how well a piece of equipment is protected from rain, water spray, and dripping water.

Procedure I tests resistance to rain and blowing rain, with variations up to 45 degrees from the horizontal.

Procedure II sprays all exposed surfaces with water for not less than 40 minutes per face.

Procedure III drips water from no less than 3 feet for 15 minutes.

What's MIL-STD-810F Method 509.4 (Salt Fog)?

Salt fog can quickly ruin equipment. 509.4 describes testing methods to determine the effectiveness of protective coatings and finishes on materials for corrosion, electrical effect and physical effects. It can also determine the effects of salt deposits on the physical and electrical aspects of materiel. The product is exposed to salt fog mist from a 5% salt solution via atomizers at about 95 degrees Fahrenheit for a minimum of four alternating 24-hour periods, two wet and two dry. The product is then examined for salt deposits that can clog or bind components, electrical malfunction, and potential short and long-term impact of any observed corrosion.

What's Intrinsic Safety?

Intrinsic safety is a requirement that may be applicable to devices that are being operated in areas with flammable gases or fuels. It means that the device is incapable of igniting those gases. In short, an intrinsically safe piece of equipment won't ignite flammable gases, See our Intrinsic Safety page, and for more detail ecom instruments' intrinsic safety section.

What's MIL-STD-810F Method 510.4 (Sand and Dust)?

Specs also often include references to MIL-STD 510.4. Those are tests that evaluate the ability to resist the effects of dust that may obstruct openings, penetrate cracks, crevices, bearings, and joints and to evaluate the effectiveness of filters.

Procedure I tests if the device can keep out blowing dust.

Procedure II determines if it is sealed against blowing sand.

Procedure III tests what happens if dust settles on the computer as that can affect heat dissipation or clog up filters.

What's MIL-STD-810F Method 516.5 (Drop)?

MIL-STD-810F 516.5 also often appears in ruggedness specs. This tests a device's ability to survive a variety of impacts and shocks. MIL-STD-810F Method 516.5 defines the purpose of the shock test to "provide a degree of confidence that materiel can physically and functionally withstand the relatively infrequent, non-repetitive shocks encountered in handling, transportation, and service environments."

Procedure IV -- Transit Drop -- is especially popular with rugged computing equipment vendors and commonly called "drop test" or "drop spec." The test requires that items weighing 100 pounds or less survive a total of 26 drops on each face, edge and corner. The 26 drops can be divided among up to five samples of the same test item, which probably means used the first until it fails, then start with the second, and so on, although the language is not clear. Drop distance generally depends on "how materiel in the field might commonly be dropped." Table 516.5-VI (Transit Drop Test) shows that items weighing less than 100 pounds with a largest dimensions of less than 36 inches, i.e. virtually all mobile computers, must be dropped from 48 inches because "a light item might be carried by one man, chest high; thus it could drop 122 cm (48 inches). It also appears that the test is conducted with the equipment off.

While most manufacturers test using Procedure IV (Transit Drop), testing according to other procedures might make more sense:

• Procedure I (functional shock) test is designed to "test materiel (including mechanical, electrical, hydraulic, and electronic) in its functional mode and to assess the physical integrity, continuity and functionality of the materiel to shock." It also says that the intent of Procedure I is to disclose equipment malfunction that may result from shocks experienced by materiel during use in the field. Eben though materiel has successfully withstood even more severe shocks during shipping or transit shock tests, there are differences in support and attachment methods and in functional checking requirements that make this test necessary. A shock apparatus is used and equipment must remain functional with a sawtooth pulse of at least 40G for 11ms (truck/vehicle-mounted 20G).
• Procedure III (fragility) is designed "to determine the maximum level of input to which the materiel can be exposed and still continue to function...". In Procedure III, drop height is defined as "the height from which the materiel might be dropped in its shipping configuration and be expected to survive." "Suggested drop height" for items up to 20 pounds is 30 inches.

Realize that all these MIL-STD-810F 516.5 procedure were really designed to measure the effectiveness of packaging, so applying this to dropping actual devices is a bit of a reach. And simply stating that a device is "tested according to MIL-STD-810F" by itself means nothing. Detailed explanation as to what was tested and what the outcome was must be included, and as a minimum, Procedures I and IV should have been done and passed.

Note that according to the DOD, field data suggests that a typical piece of equipment will be dropped from heights up to four feet an average of four to six times during its life cycle.

What other MIL-STD-810F tests are there?

The MIL-STD-810F is a very comprehensive document. As a result, a statement saying a device is "MIL-STD-810F tested" doesn't provide enough information. The MIL-STD-810F is an almost 600 page document with tests for about two dozen things that can affect a piece of equipment. The tests are:

• 500.4 Low Pressure (Altitude)
• 501.4 High Temperature
• 502.4 Low Temperature
• 503.4 Temperature Shock
• 504 Contamination by Fluids
• 505.4 Solar Radiation (Sunshine)
• 506.4 Rain
• 507.4 Humidity
• 508.5 Fungus
• 509.4 Salt Fog
• 510.4 Sand and Dust
• 511.4 Explosive Atmosphere
• 512.4 Immersion
• 513.5 Acceleration
• 514.5 Vibration
• 515.5 Acoustic Noise
• 516.5 Shock
• 517 Pyroshock
• 518 Acidic Atmosphere
• 519.5 Gunfire Vibration
• 520.2 Temperature, Humidity, Vibration, and Altitude
• 521.2 Icing/Freezing Rain
• 522 Ballistic Shock
• 523.2 Vibro-Acoustic/Temperature

Each test has various procedures and methods, and each may or may not be relevant to a particular application. Major rugged equipment manufacturers have their own testing labs where they can conduct MIL-STD-810F testing. This is generally done in conjunction with testing in an independent lab.

What is the MIL-STD-3009?

MIL-STD-3009 (also referenced as DOD-STD-3009) is another standard manufacturers of rugged equipment may refer to. It sets requirements for aircraft display equipment for use with night vision imaging systems. For mobile computers that generally means they must not interfere with night vision equipment in a cockpit.

Part of this document is the U.S. Navy MIL-HDBK-87213 Revision A (Electronically/Optically Generated Airborne Displays) that describes, among other, criteria for legibility of electro-optical display equipment and daylight readability in bright environments, which is a military requirement. This can be an issue with daylight readable displays marketed to the government and armed forces.

What is ASTM 4169?

At times, rugged product descriptions refer to ASTM 4169, Truck Transport, 11.5.2 Random test, Assurance Level 2. ASTM stands for American Society for Testing and Materials and the 4169 standard sets tests and requirements for strength, durability and protective capability of packaging. Level II stands for medium test intensities (Level I is highest and Level II lowest) and is most commonly used.

What is the MIL-STD-461E?

MIL-STD-461E establishes interface and associated verification requirements for the control of the electromagnetic interference (emission and susceptibility) characteristics of electronic, electrical, and electromechanical equipment and subsystems designed or procured for use by activities and agencies of the Department of Defense. The standard primarily applies to electronic enclosures no larger than an equipment rack, electrical interconnections between enclosures, and electrical power input from prime power sources.

Rugged computer manufacturer AMREL created a useful white paper on MIL-STD-461E here.

What is UL 1604?

You may come across references to UL 1604. This is not a governmental or industry association standard, but a certification by Underwriters Laboratories Inc. UL is an independent product safety certification organization that has been testing products and writing standards for product safety for over a century. They have over 60 testing labs and have developed over 1000 standards. UL 1604 is a certification document and covers equipment, circuits, or components intended for use in hazardous locations. This basically deals with a unit's safeguarding against causing ignition of specified flammable gas- or vapor-air mixtures.

What does "embedded" mean?

There are various definitions. "Embedded" is often used for products or projects where the computer is just part of a larger system, and not a standalone PC. Intel uses the term differently. For them, "Embedded indicates that Intel anticipates shipping the product for an extended period of time. Embedded parts typically need to be procurable for 7+ years, whereas standard parts are typically procurable for 2+ years."

What is "PCI compliance"?

In the payment processing industry, PCI stands for "Payment Card Industry." The PCI has the "Payment Card Industry Data Security Standard" (PCI DSS), which is a set of requirements designed to ensure that all companies that process, store or transmit credit card information maintain a secure environment. PCI also issued the Payment Card Industry Security Standards Council (PCI SSC) to cover the ongoing evolution of the transaction process. See the PCI Compliance Guide here.

Why is altitude testing important?

Testing procedures designed to ascertain the ability of a piece of equipment to operate at high altitude are described in MIL-STD-810G Method 500.5 2.3.1 b(1). However, that test arbitrarily uses 15,000 feet, which is more than the 7,000 feet atmospheric pressure in a commercial airplane, but a good 2,000 feet less than even Mt. Everest's base camp. Why does it matter whether a piece of rugged computing equipment can operate in high altitude? Because at 19,000 feet, air pressure drops to half from what it is at sea level, meaning there are half the air molecules available for cooling and any other operation that requires air pressure for normal functioning.

What is the difference between OEM and ODM?

OEM stands for Original Equipment Manufacturer and describes a company that designs products according to their own specifications, builds them, but the products are then sold by another company under that company's name or brand.

ODM stands Original Design Manufacturer and describes a company that builds a product based on another company's design and specifications.

http://www.ruggedpcreview.com/2_definitions.html

BGA Solder Ball Shelf Life

 

August 24, 2015

I believe BGA Solder Balls are a homogeneous mass of metals, why is the shelf life only two years? With proper handling and storage, can the shelf life be extended?

V.P.

Experts Comments

 

The solder alloy itself should not change composition significantly over a period of several years. The main potential issue is oxidation of the surface of the BGA solder ball. Even when stored properly air will eventually make its way to the solder surface and oxidation will occur. As the oxide layer grows the balls will become more difficult to solder. The rate of oxidation is slow enough that the balls will be usable for at least two years, but may be difficult to use after that time.

Tony Lentz Field Applications FCT Assembly Mr. Lentz has worked for FCT Companies for 14 years as a Lab Manager and Facility Manager. Over the last 2 years he has worked in Field Application for FCT Assembly. He holds BS and MBS degrees in Chemistry.

The shelf life, as defined by the manufacturer, takes into account all aspects of the package, but let's stick to the solder ball characteristics. You are correct that the balls are a homogeneous alloy. So what might degrade after two years? Assuming that the parts are stored in MBBs compliant to J-STD-033, moisture will not play a role; the MBB and desiccant will protect against moisture ingress for approximately three years. The MBB does not, however, protect against oxygen, and the surface of the balls will oxidize over time. It is very likely that, after two years properly stored, solderability will be quite acceptable. It's just not guaranteed. Can we extend this time? The answer is, certainly we can, if we exclude oxygen. For long-term storage of parts for aerospace applications, where a program needs to be supported for a decade or more, we use nitrogen inerted cabinets, which both exclude oxygen and moisture. This eliminates surface degradation of parts. It does not, however, eliminate growth of intermetallic compounds, which will occur over time. IMC growth only impacts solderability when it grows through to the surface, however, which is something you won't see on BGAs. Bear in mind that any steps you take to extend solderability still don't affect the warranted period for solderability, only the practical life.

Fritz Byle Process Engineer Astronautics Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.

Unfortunately solder suppliers have no control how their products are handled once they leave the factory. Also, the products are shipped to a wide variety of locations and climates including humid areas as well as locations near salt water. With this knowledge, the solder has to protect against returns involving old and oxidized product. For this reason these forms of solder are assigned a shelf life. With that said, the assigned shelf life is often conservative, and the product, if stored and handled properly and used with a flux, are usable well beyond the stated shelf life. I often encourage the end user to establish an internal protocol to recertify or lengthen the shelf life of the product. This would typically involve simple wetting tests with fluxes and substrates representative of what is used in their actual products. Some solder suppliers offer testing to "recertify" the product. However, the fee for so doing, is often near or close to the cost of just buying new product.

Eric Bastow Senior Technical Support Engineer Indium Corporation Eric is an SMTA-certified process engineer (CSMTPE) and has earned his Six Sigma Green Belt from the Thayer School of Engineering at Dartmouth College. He is also a certified IPC-A-600 and 610D Specialist. He has an associate's degree in Engineering Science from the State University of New York and has authored several technical papers and articles.

Many BGA manufacturers have a standard 2-year shelf life for their products.  I have also seen others which recommend just one year. Proper handling and storage may extend the life of the BGA but it is not a predictor of its performance and reliability.  One way of predicting shelf life would be to expose the components to some type of accelerated aging process to see if there is a change in component's physical properties along with its performance within the circuit.

Edithel Marietti Senior Manufacturing Engineer iDirect Edithel is a chemical engineer with 20 year experience in manufacturing & process development for electronic contract manufacturers in US as well as some major OEM's. Involved in SMT, Reflow, Wave and other assembly operations entailing conformal coating and robotics.

http://www.circuitnet.com/experts/87700.html

The War on (SMT) Failure

The war on failure from Marcelo Chirai

Accelerometer Mounting Accessories

Many accelerometer adhesives have been successfully used for securing mounting bases to test objects. These include epoxies, waxes, glues, gels, and dental cement. Some provide more permanent attachment than others. Stiffer adhesives provide better transmission of high frequencies. Adhesives should be selected which perform adequately for the required application and environmental conditions. PCB® offers petro wax and quick bonding gel. How do I remove an accelerometer adhesive mount sensor? Obviously, the mounting of an accelerometer is critical to a successful measurement. Accelerometers have a cost.  You want to protect your investment.  The proper removal of an accelerometer extends its useful life. Improperly removing the sensor may cause immediate damage and failure. Do not use an impact technique (hammer, chisel, knife) to remove the sensor. Soften the adhesive first by use of a debonding agent. Then use a removal tool by gently twisting the accelerometer free of its mount.  To avoid damaging the accelerometer, a debonding agent must be applied to the adhesive prior to sensor removal. With so many adhesives in use (glues, dental cement, epoxies, etc.), there is no universal debonder available. The debonder for the Loctite 454 adhesive that PCB® offers is Acetone. If you are using anything other than Loctite 454, you will have to check with the individual manufacturer for the debonding recommendation. The debonding agent must be allowed to penetrate the surface in order to properly react with the adhesive, so it is advisable to wait a few minutes after applying before removing the sensor.

http://www.pcb.com/TestMeasurement/Accelerometers/Access/Adhesives.aspx

Calculation of a Shock Response Spectra

Calculation of a Shock Response Spectra from Marcelo Chirai

Excess Flux Residue After Hand Soldering

July 10, 2015

We observe an excessive amount of flux after hand soldering terminals using flux cored wire solder. See the image.

Is this amount of excess flux normal?

Is there something wrong with our manual soldering operation?

K.K.

Experts Comments

The answer is it depends but this appears to be excessive on the contact, but was a different amount of solder wire or larger core used to solder the sample. I would be more concerned is the flux benign or still corrosive (no clean flux requires additional heat to complex the flux to create a benign residue and this looks like it is far from the solder joint heating). The other question to ask if this is insulative do you want it on the contact that is designed to make electrical contact.

Terry Munson President/Senior Technical Consultant Foresite Mr. Munson, President and Founder of Foresite, has extensive electronics industry experience applying Ion Chromatography analytical techniques to a wide spectrum of manufacturing applications.

The picture shows flux residue from soldering using solder wire which is not uncommon. Flux residue will depend on the percentage of flux in the wire. Flux percent by weight will vary from 0.5% to 3% in solder wires and higher percentages will leave more visible flux residue. Less flux in the wire, less flux residues, however you need a good percentage to enable ease of soldering. Usually 1, 2 or 3 % flux is best with 0.5% being more difficult to use by operators. If the residue is from flux that are no-clean in nature the residue will not cause issues normally. Most no-clean solder wires are described as ROL0. No-clean, RA, RMA flux wires have fluxes which are resin based and slightly higher or lower soldering tip temperatures will not impact the volume of visible flux. Resins tend to have high boiling points and do not vaporize with soldering tip temperatures. If temps are too high the resin will darken and burn. This will render it harder to clean off later.

Peter Biocca Senior Market Development Engineer Kester Mr. Biocca is a chemist with 24 years experience in soldering technologies. He has presented around the world in matters relating to process optimization and assembly. He has been working with lead-free for over 8 years. He is the author of many technical papers delivered globally.

Flux residue is proportional to the percentage of flux in the wire and the amount of wire fed into the joint. Wire solder that is '2% flux core' is 2% flux core by weight - it's approximately 50% by volume. Therefore, if the joint accepts a lot of solder, then there is going to be more residue. In the image you provided, the terminal looks to hold a lot of solder therefore you could expect more visible residue, but I would not consider it excessive. You could experiment with different manufacturers wire solder products to see if they leave less residue as flux formulation can significantly impact location/appearance/volume of residue.

Tim O'Neill Technical Marketing Manager AIM Tim O'Neill is the Technical Marketing Manager for AIM Products. AIM is a global supplier of materials for the PCB assembly industry including solders, fluxes and thermal management materials. Tim has a B.A. from Assumption College and post-graduate studies in education. He has 20 years of experience in the electronics soldering industry, beginning his career in 1994 with EFD and was key in business development of their fine pitch solder paste dispensing technology. Tim joined AIM in 1997 and has since assisted many clients with assembly challenges, specializing in Pb-Free process development and material selection.

First, it is assumed that this is a No-Clean flux-cored solder wire.  If not, then the residue would have to be removed. If this is a No-Clean flux-cored solder wire there is nothing wrong with your soldering but ways to make it look better. Seeing that the flux-cored solder wire has been heated fully to alloy melting, the flux within has been heated sufficiently to Remove oxides as is needed for joining and Remaining flux residue will be fully activated and rendered harmless in terms of corrosion.  The amount of residue can be controlled somewhat by adjusting the diameter of the flux-cored solder wire. Try using a smaller diameter for less flux residue; the smallest diameter that will do the job. The IPC-610 standard for workmanship allows flux residue resulting from hand-or machine-soldering as long as the residue has been heated sufficiently to activate it. Any surface that has achieved soldering temperature will certainly render the flux residue activated.

Gary Freedman President Colab Engineering A thirty year veteran of electronics assembly with major OEMs including Digital Equipment Corp., Compaq and Hewlett-Packard. President of Colab Engineering, LLC; a consulting agency specializing in electronics manufacturing, root-cause analysis and manufacturing improvement. Holder of six U.S. process patents. Authored several sections and chapters on circuit assembly for industry handbooks. Wrote a treatise on laser soldering for Laser Institute of America's LIA Handbook of Laser Materials Processing. Diverse background includes significant stints and contributions in electrochemistry, photovoltaics, silicon crystal growth and laser processing prior to entering the world of PCAs. Member of SMTA. Member of the Technical Journal Committee of the Surface Mount Technology Association.

The amount of flux does not seem excessive. Soldering this type of terminal requires a fairly high volume of solder, so there will be more residue than for a smaller joint. It may be possible to reduce the amount of residue by purchasing solder wire with a lower flux percentage. Speak with your solder manufacturer about what you are now purchasing, and whether a version with lower flux percentage is offered. If it is, you will need to test it to see whether the reduced flux activity due to less flux is adequate for the application. One other thought; if the flux running down the terminal is of concern, re-orienting the terminal during soldering may avoid this, but of course the residue will still be present.

Fritz Byle Process Engineer Astronautics Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.

From the photo is appears that your operator is adding flux prior to hand soldering. The flux is too far away from the solder joint so I would check this first. If this is not the case, from the photo it appears that the flux is not activated (as shown) which could mean: Soldering iron temperature is too low. Soldering time on the joint is too short and not activating the flux. Flux content in the solder core is too great. Perhaps considering a lesser percentage.

Gary Goldberg President and CEO PROMATION, Inc. Mr Goldberg has practical experience in production line layout, process flow and cycle rate analysis. He knows how to avoid bottle necks and most related PCB or pallet handling questions.

To determine if the electrical performance will be compromised, a surface insulation resistance test (available in the IPC Test Methods) will show if the residue will be sufficient enough to compromise the finished PCB. Hand soldering temperatures can vary significantly.  Soldering tip in relation to board density (which can act as a heat sink) , not to mention the human factor, can add up to inconsistent heating ultimately leading to excessive residue.

Stephanie Nash Director Integrated Ideas & Technologies, Inc. Stephanie Nash is the Director of Technical Services & Marketing for Integrated Ideas & Technologies, Inc., a premier manufacturer of SMT stencils. She has been instrumental in the stencil design and technical support.

http://www.circuitnet.com/experts/87080.html