Technical Articles Archives

Latex Gloves – Are You Allergic?


Many industrial manufacturing environments require workers to wear protective gloves, including during electronics and medical device production and assembly. Latex gloves not only protect workers from harmful chemicals but also protect products from worker contact and contamination during manufacturing Read more

ST 925 SMT Rework System–Three favorites combined into one nice savings


Save a few steps--and some money--with the Pace 925 SMT Rework System Pace has introduced a new low-cost “combination” system ideal for surface mount technology (SMT) rework. It’s worth adding up the savings by comparing the a la carte prices Read more

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

Why Lead-free Soldering is Better

Posted on by Andy in Technical Articles Leave a comment

It’s been a year since the Waste Electrical and Electronic Equipment Directive and the Restriction of Hazardous Substances Directive (RoHS) have mandated that lead be eliminated from electronic systems. Consequently, this has led engineers to a high interest in using lead-free soldering alloys. Some of the harmful alloys that are used in normal soldering are tin, copper, silver bismuth, indium, zinc, and antimony.

So why are these dangerous to humans everywhere? Prior to 1930, all homes used lead pipes to transport water to and from houses. Now, most homes use copper piping. However, this is still a problem because most of these copper pipes were assembled using solder, which is approximately 50% lead. This harmful lead, whether through piping or from the solder used to blend the pipes, is especially prominent in the water a few years after installation of the pipes.

In addition to lead solder being applied in piping, it is often used in some basic household staples like canned food. Canned fruit and vegetables, canned juices, and tomato sauce are extremely likely to contain high levels of lead from the solder used to solder the tops of the cans on. In spite of these dangers, the FDA still has not banned lead solder in food packaging, but many manufacturers are taking precautions against this.

Some of the alloys that could replace soldering products containing lead are Sn95.5Ag3.9Cu0.6 for surface mount reflow soldering and Sn99.3Cu0.7 for wave soldering. Sn96.5Ag3.0Cu0.5 is recommended for reflow soldering with SnAg and SnZnBi as alternative alloys. The SnAgCu alloy family is the most popular choice at present for lead-free alternatives.

Kester Lead-Free Solder Paste There are many lead-free products for sale including lead-free solder paste, lead-free flux, lead-free solder wire, and other lead-free products that can be used as substitutes for lead products. If you haven’t been living under a rock lately, you have probably heard of the Mattel fiasco where over a million toys were recalled because of the lead paint that was used on them. People are so worried about children being exposed to lead that they are pushing Mattel to set up a fund to test children for lead poisoning. This recent disaster will hopefully bring much needed attention to the dangers of lead.

For more information on how you can safely solder using lead-free products click here or for some technical information on lead-free alloys visit the NIST website. For ways to guard yourself against lead in your environment check out the Environmental Health Threats website.


ESD vs Anti-Static vs Dissipative vs Conductive vs Insulative

Posted on by Andy in ESD News, Technical Articles Leave a comment

 

ESD-Safe Symbol In order to distinguish the differences between these five terms, you need to know what each one means.

ESD (as defined in the previous post) is an acronym for electrostatic discharge. Many times it is used incorrectly as a term for something that is “electrostatic discharge safe.”

The terms anti-static, conductive, and dissipative are all terms that subdivide ESD into more detail. Something insulative is not considered ESD safe.

Materials are divided into these terms based on their individual surface resistance. Surface resistance is a measurement of how easily an electric charge can travel across a medium. Conductive materials are materials that have a surface resistance of less than 1 x 10 5 ohms/square. Dissipative items have a surface resistance of more than 1 x 10 5 ohms/square but less than 1 x10 11 ohms/square.

Anti-static materials are generally referred to as any material which inhibits triboelectric charging. This kind of charging is the buildup of an electric charge by the rubbing or contact with another material. An insulative material is one that has a surface resistance of greater than 1 x 10 12 ohms/square.

For more ESD products and ESD information, visit the All-Spec website or the Electrostatic Discharge Association website.

Interested in the learning more about the basics of ESD?


How to choose an ionizer

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There are a few things to keep in mind when choosing an ionizer.  First start by deciding which style of ionizer will work best for you.  This includes overhead ionizers, desktop ionizers, and gun type ionizers.  Then decide on whether or not you would like DC or AC ionization.  Each of these choices will narrow your selection from the many available types of ionizers.

Each style of ionizer has its advantages and disadvantages.  Overhead ionizers, like the Aerostat Guardian Overhead Ionizer (4004063), are generally the most expensive;  however, they save desk space by being hung from above and provide continual ionization over an are3M 960 Mini Ionized Air Blowera.  Desktop ionizers, like the 3M 960 Mini Benchtop Ionizer (to the right), are generally the least expensive and still provide continual  ionization over an area; however  they take away from the desktop space by sitting on the work surface.  The third style is the gun type ionizers, like the Simco Top Gun (4005105) below. These are used mainly for pinpoint control of the ionized air flow, and are not used when trying to cover an entire area with ionized air.  They work really well as a “blow-off” gun to get rid of dust or other contaminants without using normal shop air which can introduce a charge.  The negatives are that they normally require the use of an air compressor which is noisy and fairly expensive. It also doesn’t cover the entire work surface, and without the additional “hands free kits,” you would need to hold it in order to use it.

Hand Held Air Ionizer The difference between DC and AC ionization is the way the emitter points function.  In AC, like the Simco Aerostat models, the same emitter point alternates between releasing positive and negative ions.  This means they inherently have a voltage balance.  This is because if an emitter gets dirty and isn’t functioning, the other emitters are still alternating between positive and negative ions.  This also means that the ions are closer together which makes it more likely for them to recombine. This means normally higher fan speeds are needed to reduce the time between the fan and the surface that needs to be ionized.  DC ionizers, like the 3M TM960, have separate emitters for positive and negative ions.  This means that it’s a little more difficult to ensure a low voltage balance and if one emitter stops working, it throws the unit out of balance.  These types of units require a lot more consistent maintenance/monitoring to ensure a good voltage balance.  The benefits are that the emitters are separate so there is less of a chance of recombination of the ions.  This allows the DC units to operate at a lower fan speed which is very beneficial when your components are small or you are in a clean room.

Check out our selection of ionizers at All-Spec’s website.


What is air ionization?

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Air ionization can be an important solution to dealing with electrostatic discharge (ESD) because of the damage that ESD can cause when air is not ionized in a working environment.

Problems that can occur include:

  • Products, process tools, or components being damaged due to a direct ESD event.
  • Surface contamination due to electrostatic attraction of particles (ESA).
  • Latch-up of process equipment because of ESD and resulting in electromagnetic interference (EMI).

Air Ionizer Some manufacturing processes use non-conductive materials and isolated conductors. These processes then generate and carry large charge potentials, which can negatively affect production of certain types of equipment. Ionizers prevent the accumulation of static charge on any object that cannot be grounded. This static charge needs to be removed quickly because it will likely cause an ESD event.

The main method to stop these ESD events is using wrist straps, ground straps, and conductive footwear to ground the user and equipment. However, in some cases, these methods are impractical and air ionization then becomes the best option.

All air ionization methods do the same thing: they move electrons between gas molecules. Without getting into too much scientific detail, ionizers can decrease tool repair costs and increase equipment uptime by 50%. They also protect ESD sensitive equipment, control particle contamination, and reduce process equipment lock-up. This is done by introducing ionized particles to neutralize the charges that are already built up.

See our article on how to choose the right ionizer or visit All-Spec’s website for our selection of all types of ionizers.


What is ESD?

Posted on by Andy in ESD News, Technical Articles Leave a comment

ESD-Safe Symbol Before you can understand ESD (electrostatic discharge), you first need to understand what static electricity is. Static electricity is the buildup of an electrical charge through an imbalance of electrons. This is most obvious when your hair stands up or when your clothes stick together right after pulling them out of the dryer. This happens because one item has a positive charge and the other item has a negative charge.

Technically speaking, an ESD event is defined as an event where there is a transfer of a charge between two bodies with different electrical potentials. The most notable ESD event is the occurrence of lightning (300,000,000 volts). However, the most common one you will physically experience is the shock you receive when you touch a metal doorknob after walking across a carpet on a cold dry day. Lightning is obviously an ESD event on a grand scale with huge transfers of electrons compared to the small discharge present when touching the doorknob.

If we don’t get injured when we are shocked by touching the doorknob, then why do we have precautions against ESD? ESD does do damage when it happens. Just like a lightning bolt can potentially kill a person, a small ESD event can potentially destroy an electric component. Small electronic components such as Service Mount Devices (SMDs) are very susceptible to ESD events. Whereas a person can only begin to feel an ESD event between 2,000 and 3,000 volts, a small component can be damaged or even be destroyed by just a few volts of discharge. By wearing grounding equipment and following ESD precautionary procedures, we reduce the risk of damaging these components.

For our selection of ESD products visit the All-Spec website or the Electrostatic Discharge Association website for more information.

Looking for more information about the basics of ESD?