Technical Articles Archives

Metcal’s CV-5200 Connection Validation Soldering Station Changes Everything


You may or may not have heard about Metcal’s new soldering station, the CV-5200. The evolutionary tool removes much of the reliance on visual inspection of hand-soldered joints and adds a second, more technology-driven method for validating a successful Read more

Seven Things to Know About Qualifying Your Product to a U.S. Military Specification (MIL-SPEC)


Qualifying the SCS 81705 Series anti-static shield bags to military standards There are a few, sometimes complicated steps to go through before your product can qualify for a particular military specification. SCS recently introduced their new 81705 Series static shield Read more

Get Lean with 5S Workplace Principles


5S - Sort, Set in Order, Shine, Standardize and Sustain Recognized as one of the strategies associated with “Just in Time” manufacturing (Toyota Production System), the 5S system for workplace organization and standardization originated in Japan. The “5” relates to Read more

PCB Rework – Evolving Cleaning Methods

Posted on by Barb N. in Printed circuit board rework, Technical Articles Leave a comment

Smaller devices makes PCB rework harder.

Today’s manufacturers of printed circuit boards (PCBs) strive for quality and drive operation yields close to 99% and above – yet some boards will still fail functional tests when coming off the assembly line and need rework. With the increase of smaller, better PCBs for smartphones and tablets, PCBs can cost upwards of $200 each. Original equipment manufacturers (OEMs) must develop effective and efficient rework processes and save the damaged boards when possible to minimize scrapping PCBs and operation losses.

The value of reworking faulty boards is quite clear. With the development of more sophisticated boards and the continuing demand for smaller and smaller devices, performing manual rework has become increasingly difficult.

Previously thought of as a very specialized process used by few OEMs, contactless cleaning is quickly becoming mainstream and mandatory for most PCB manufacturers to stay competitive and meet customer demand.

When performing PCB rework, technicians generally follow three steps –

  1. Remove the non-working component
  2. Clean the leftover solder from the ball grid assembly pads
  3. Replace the non-working component with one that works

Today, both the first and third steps have been automated and can be completed on rework machines. The second step, however, continues to remain in the hands of a skilled technician because of the intricate, critical nature of properly repairing a damaged PCB. Boards can be cleaned using different kinds of tools—from a wicking braid to a soldering iron—along with specialized tips for detailed work. The skill level of the technician can determine whether a board comes through the process undamaged and how often.

One common way a board can be damaged is during manual cleaning. If the soldering iron dissipates for a moment from the pad, it can cause the pad to stick to the wick. As a result, the pad can chip or lift totally off when the technician pulls the tool away. If the pad is destroyed, the PCB becomes scrap.

To help ward of this king of damage, manufacturers are creating thicker PCBs with multiple inner layers of copper.

Open vias and solder resist damage

Unfortunately, the newer PCBs can cause heat to dissipate faster when using a handheld cleaning tool —making sticking challenges even more of a problem.

Additional issues like molten solder flowing into electrical connections or into vias can also occur, causing shorts in the board. Also, if solder is removed inconsistently from the pads, the components may not adhere well and portions of the solder resist may be accidently removed by the wick. The solder can then flow into electrical connections and cause bridges and shorts when it’s put back into the rework machine.

One of the worst case scenarios, in addition to a PCB becoming scrap, is the creation of pad craters within the fiberglass substrate. These cannot be seen during inspection or by X-ray. Pad craters can happen when an operator presses too hard with their soldering iron or rests an excessively hot solder tip for too long on a board.

In this kind of damage, the pad and the solder balls remain connected to one another; however, the pad is not fully anchored to the circuit board, leaving it vulnerable to just the smallest jolt. If the product goes to market and this happens, the result may cause customer dissatisfaction.

Tough cleaning woes

Two different types of solder are used in manufacturing, with melting points of 183° C and 302° C (361° F and 575° F) respectively. Manual cleaning can change the melting temperature of solder on pads and become too low to form a connection, causing a dry joint. Also, package-on-package (PoP) chips cannot be manually cleaned with assurance or without the threat of the package bottom melting.

Advanced chip technology also causes PCB cleaning challenges. Even though one company’s breakthrough technology makes it almost impossible for criminals to access data, it also makes components difficult to clean due to differing pad sizes and uneven solder volumes.

Ceramic ball grid arrays present another huge challenge. These highly specialized boards, along with the components used in aerospace, military and other high-reliability applications, have become extremely hard to successfully, manually rework, and usually have to be trashed if faulty.

Alternatives – Contactless cleaning

Contactless cleaning or scavenging can significantly reduce the challenges associated with manual cleaning, and can be a substitute method in many applications. If no contact is made with the pad or board, possible mechanical damage is greatly reduced. Instead, precision-controlled tips clean pads too small and too close together for technicians, while software and equipment continually control thermal profiles.

All-in-one designs

Contactless cleaning has generally been used on very large, high-end machines or as an optional, retrofitted add-on that allows for the cleaning function to become part of the removal and replacement steps on a single rework machine. Stand-alone contactless cleaning machines require a much lower capital investment, plus other added benefits like great throughput.

The standalone machines take only a single operator to run and can increase the speed of an assembly line operation if used next to a standard rework machine. They offer excellent flexible opportunities for manufacturers to easily add contactless capability to their existing operations. If they presently have a standard rework machine and no scavenger add-on, a contactless cleaning machine can be added quickly to work side-by-side with their current system. This is a useful route if suddenly the OEM needs a quick way to add capability because of increased customer demand.

As chip sizes shrink, and production struggles to keep up with an ever-expanding demand for smaller and more powerful electronics, rework processes must continue to develop.

From a Metcal article –

From the original article – The Evolution of Cleaning Methods,in PCB Rework by Robert Roush and Paul Wood, Metcal


Ten Things You Should Know About LEDs

Posted on by Barb N. in LEDs, Technical Articles Leave a comment

LEDs – Know the basics

From manufacturers to universities, LEDs are quickly replacing conventional light sources. Knowing a few basics may help you weave your way through this wave of the future. Here are lighting manufacturer Luxo’s suggestions for things you should know about LEDs.

  1. What is an LED (Light Emitting Diode)?

An electronic component that generates light in a semi-conductor material. Under the right circumstances a diode may provide different wavelengths of seeable light.

  1. LEDs are not new.

Some people may recognize LEDs as being the red or green signal markers on hi-fi’s and TV sets—usually low-powered LEDs. High-powered LED costs have dropped in the past couple of years and operate at powers of around 1 W making them attractive to most industries. Forecasts show that by 2020, almost 50 % of all new and replacement light source unit sales will be based on LEDs–and because LEDs cost more than conventional lighting, the value of the LED sales will be even higher.

  1. LEDs last longer and don’t need to be replaced as often as most conventional lighting.

LEDs don’t have any movable parts or filaments to break so they last longer. This makes them very convenient with installations and replacements of challenging luminaires especially those at excessive heights and other difficult to service locations, e.g., windmills, telecommunication towers and chimney stacks.

  1. LEDs are more efficient than many conventional light sources.

All of the light emitted by an LED points in one direction allowing for less reflections inside the luminaire making them very suitable in situations where only downward lighting is needed. However, if both upward and downward light distribution is needed, the LED is less suitable, e.g., if compared to a T5 fluorescent lamp.

  1. LEDs offer new possibilities for color tuning to evolve.

Because LEDs are electronic components, they can be easily controlled (tuned) using software and control gear. An LED luminaire color can be mixed and may include red, blue and green diodes resulting in either colored light or white light.

The different color temperatures make it possible to produce cool and warm colored light. This capability comes in handy in office environments, schools and hospitals where concentrated light might be warranted, e.g., during a patient examination. LEDs can also be tuned to a warm temperature where more relaxing lighting may be desired, e.g., yoga cool down.  This attribute is also being maximized to increase the growth of plants and reduce water consumption.

  1. Temperatures inside a diode define an LED’s lifetime.

Heat management is the key to controlling the life of an LED and the temperature inside the diode. The temperature within an LED may get very high causing it to slowly emit less and less light. The higher the internal temperature, the faster the lumen degradation. Higher temperature on the LED chip (known as the junction temperature) speeds up the decline.

Lumen – a unit of luminous flux in the International System of Units, that is equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions. 

  1. Understanding LEDs and lifetime, and diminishing output.

The amount of light from the light source at a future point in time is called the lamp lumen maintenance factor, or LLMF.  The lifetime of an LED module is defined as the time it takes until its light output, or lumen maintenance, reaches 70% of the initial output (L70). This means the module doesn’t die instantly as do most conventional light sources; instead it slowly dims down. The luminaire industry has standardized LED lifetime L70 to a minimum of 50,000 hours.  This corresponds to an LLMF of 0.7 as long as the lifetime of the lighting installation is set to the same amount of hours.

  1. The color spectrum of an LED comes from its color rendering capability.

Sunlight, halogen and metal halides possess complete spectrums while sodium lamps,

fluorescent tubes and LEDs have varying power distribution curves. Cool white LEDs have more blue light in them; warm white LEDs have more yellow and red light. 

  1. The LED driver is the auto pilot of the LED luminaire. Proper drivers help LEDs to stay cool and stable.

LED drivers differ from conventional power supplies because an LED driver responds to the varying needs of the LED supplying constant amounts of power as its electrical properties change with temperature. Choices include constant current for serial connections or constant voltage for parallel connections.

LED driver advantages –

  • Short response time – switches and dims immediately and can dim all the way from 0.1 to 100%
  • Very efficient at producing colored light

 

  1. Watch the LED’s Total Cost of Ownership (TCO)

Many applications warrant using LEDs, but not all. Analyzing the TCO when investing in LEDs including the energy costs, lamp change costs and cleaning costs can be crucial. Take time to consider all costs and suitable applications before making a final decision to transition or make new investments in LEDs.

 

 

Infographic showing the history of the LED light

 


The Benefits of ESD-Safe Turntables -Take One for a Spin

Posted on by Barb N. in Cleanroom, ESD News, Product Reviews, Static Control Tips and Tricks, Technical Articles Leave a comment

Remember the lazy Susan?

imagesOnce a staple on every dining room table where with a spin of a wooden disc your salt and pepper shakers suddenly appeared in front of you. The same idea works for an ESD-safe turntable, however this disc does much more than turn.

Just like the revolving server, the turntable rotates to make working on large products and assemblies easier. With an ESD-safe turntable you avoid lifting heavy objects and–potential back injuries. With just a turn of the wheel you can access your next work area with ease—no lifting, lugging or jostling into place. And of course, the turntable eliminates electrostatic build-up.

The devices can be used on grounded or ungrounded surfaces, however on ungrounded surfaces the turntable must be grounded. The sizes range from 12” to 20” and come in different shapes depending on your application and preference.

esd-turntable

ESD-Safe Turntable – Not for use with food. Great for heavy objects.

The ESD-safe turntable can be an invaluable tool in the electronics industry and has become a staple in its own right at many workstations. See a choice of ESD-safe turntables at All-Spec including these brands – Protektive Pak, Fancort, Sovella and Desco.

Summary –

  • Keeps heavy objects grounded and shielded from static
  • Eliminates heavy lifting or transport
  • Protects workers, products and components
  • Useful all kinds of heavy assembly, rework or maintenance jobs
  • Removes charges on contact with grounded ESD surfaces

 

 

SEE HOW IT WORKS – Protektive Pak ESD Turntable


ESD–Smaller Parts, Bigger Problems

Posted on by Barb N. in ESD News, Static Control Tips and Tricks, Technical Articles Leave a comment

ESD Sparks Conversation

It’s no shock that smaller electronic parts have been causing bigger ESD (electrostatic dissipation) problems–serious problems that cause component damage and money. How much damage depends on the sensitivity or susceptibility of the device.

Thankfully you can put controls in place to significantly reduce ESD incidents. Preplanning, understanding causes and solutions, and wearing special fabrics and components will help.

Preplanning

  1. Design products and assemblies to be as protected as practical from ESD damage
  2. Decide how much of the environment needs to be controlled
  3. Identify the areas needing protection and ESD sensitive parts
  4. Define the electrostatic protected areas (EPAs)
  5. Define the areas where ESD sensitive parts (ESDs) will be handled
  6. Eliminate static generating processes to reduce electrostatic charge generation; keep processes and materials at the same electrostatic potential; provide appropriate ground paths to minimize charge generation and accumulation
  7. Use grounding, ionization, and conductive and dissipative static control materials to dissipate and neutralize
  8. Use grounding, ionization, and conductive and dissipative static control materials to dissipate and neutralize
  9. Protect products from ESD with proper grounding or shunting, static control packaging and material handling products

Areas needing ESD protection

Causes and effective solutions

ESD is a tiny version of lightning. As the current dissipates through an object, it’s seeking a low impedance path to ground to equalize potentials. In most cases, ESD currents will travel to ground via the metal chassis frame of a device. However, it’s well known that current will travel on every available path.

Table showing esd causes and solutions

Control the area

The first step is to ground all components of the workstation and the personnel (work surfaces, equipment, etc.) to the same electrical ground point, called the “common point ground” i.e., system or method for connecting two or more grounding conductors to the same electrical potential.

All-Spec carries all of the products listed below to help you control your environment and keep it safe from ESD.

ESD control materials

 


BGA Conductor Receives a Path Redesign

Posted on by Michelle R. in Technical Articles Leave a comment

From design to production, circuit boards require hours of planning, execution, revision and more revision to arrive at a final product (until the next model comes out). Recently, BGA conductors were evaluated and found to have a design that contained a flaw involving 23 of the 676 balls on their component. The problem? They weren’t connected where they needed to be connected.

blogBGA

With re-routing as the only viable solution, the design team set about what was a major undertaking. Had the pads that required re-routing been located on the perimeter of the BGA’s layout, the rework would have been much easier. However, their actual location proved to be a challenge that would require meticulous planning.

It was decided that the newly routed pads needed to extend from the center of the component, and they would stretch to the outside of the package footprint so wires could be added to the newly designed pattern of the surface mount pads.

Easy in theory. A bit more challenging in practice.

The initial design placed the new circuits too close to those on the circuit board. Creating a configuration that prevented the newly laid circuit from interfering with the solder paste stenciling and BGA placement required several intricate operations before the new paths were placed where they needed to be.

Whether constructing a new design or improving on a current one, trust your electronic assembly applications to Hisco, where we have the best names in the industry available by phone or on the internet. Call us or visit us online today!


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