Are there any problems using cell phones near ESD devices or assemblies?

August 27th, 2015

Some investigators in the disk drive area have found that under certain test conditions that GMR heads can be altered or damaged if near an activated cell phone. The testing was contrived a bit in that a large coaxial antenna was attached across the magnetic stripe of the GMR head and the cell phone operated within inches of the antenna. Naturally, this sort of condition should not occur in actual practice but it does show that the sensitivity of the particular item was quite high (easy to damage). Of course a charged piece of plastic waved in front of the antenna would have resulted in the same problem or worse. The signal strength of a cell phone should not cause problems to anything of a practical nature. Have a look at papers presented in the EOS/ESD Symposia from 1998-2000 regarding testing of sensitive items like GMR heads for disk drives.

Transforming Technologies

What is the difference between antistatic, conductive and static dissipative?

August 27th, 2015

The terms conductive and static dissipative typically refer to resistance or resistivity ranges used in the evaluation of ESD control materials and products. By definition, a conductive material has a surface resistivity of less than 1 x 10E5 ohms per square or a volume resistivity less than 1 x 10E4 ohm-cm. A static dissipative material has a surface resistivity of 1 x 10E5 to 1 x 10E12 ohms per square or a volume resistivity of 1 x 10E4 to 1 x 10E11 ohm-cm. These definitions appear in the ESD Association Glossary as well as in various other static control standards documents. For some materials, surface resistance rather than surface resistivity is often used to define these terms. In this case, a simple conversion factor is applied, dividing the resistivity ranges by 10. Thus conductive becomes less than 1 x 10E4 ohms and static dissipative becomes 1 x 10E4 to 1 x 10E11 ohms, provided that the appropriate electrodes with the correct geometric conversions are used. ANSI/ESD S11.11 provides additional information on this issue. The term antistatic, however, does not refer to resistance or resistivity. By definition, the term refers to a material that resists tribocharging. At one time, the term referenced a resistance value, but it was severely misused and today no longer represents any resistance range.

Source: Transforming Technologies

Setting up ESD-Safe Work Stations. Some Guidelines to follow.

August 27th, 2015

 We are setting up work stations for handling static sensitive devices. What are some guidelines we should follow to be sure we are adequately protecting our components?

An ESD protective workstation refers to the work area of a single individual that is constructed and equipped with materials and equipment to limit damage to ESD sensitive items. It may be a stand-alone station in a stockroom, warehouse, or assembly area, or in a field location such as a computer bay in commercial aircraft. A workstation also may be located in a controlled area such as a clean room. The basic concept of the ESD protective workstation is to keep all materials and personnel at the same electrical potential. Electrostatic discharge occurs when two objects at different potentials come into contact with or in the proximity of each other. If the potentials are equal, no discharge occurs. The key ESD control elements comprising most workstations are a static dissipative work surface, a means of grounding personnel (usually a wrist strap), a common grounding connection, and appropriate signage and labeling.

Source: Transforming Technologies

Are ESD-Safe wrist straps always necessary?

August 27th, 2015

Are wrist straps necessary if all other ESD precautions are taken (i.e., two ground [foot] straps, jacket, dissipative flooring, grounded mats, etc.)? If so, why?

Wrist straps are not necessary if an operator is wearing two foot grounders on a conductive grounded floor and doesn’t lift both heels/toes at the same time, like some people do when sitting down. If an operator is also wearing a esd jacket, but is not electrically connecting the jacket to either their body’s skin or ground, then the jacket is providing only partial protection. Charges on the jacket may have no where to go or discharge to if the jacket is not grounded. A popular way to ground the jacket is with a coil cord either attached to a snap on the waist area of the jacket or via a wrist strap snapped to the inside cuff of an ESD jacket.

Source: Transforming Technologies

Flux Test Kits, what do they do?

August 27th, 2015

Test kits are acid titration kits. As solvent evaporates, the acids in the flux become more and more concentrated. The kit is used to determine the acid number of the flux. The test is a simple drop test with an indicator for the endpoint (similar to a swimming pool test). You count the drops and then go to a chart. From the chart you determine how much thinner to add to bring the acid number back down to spec. Traditionally flux control is maintained by measuring the density of the flux and adding thinner as the flux thickens. This is a good method for fluxes with high solids contents. A slight change in density corresponds to a small change in the flux. The no-clean fluxes have low solids percents (typically 2 or 3 %) so a small change in the flux density could reflect the change in solids of 25-30%. This would put the acid level unacceptably high. The test kits are more accurate than using density measurements as a way to monitor the flux.

Source: Kester Solder Co.

Are Kester “44” rosin residues harmful to an assembly?

August 27th, 2015

The “44” flux residues are non-conductive and non-corrosive. Residue removal would normally be for cosmetic reasons. If the assembly is in a heated environment and sees temperatures of over 160°F the flux residues will re-melt. When liquid (at high temperatures) the residues are conductive.

Do rosin flux residues need to be removed?

August 27th, 2015

Rosin flux residues are non-conductive and non-corrosive. Under normal circumstances they do not have to be removed from a printed circuit assembly. Rosin residue removal would be for cosmetic considerations. In an environment where the working temperature of the assembly will exceed 200°F the rosin residues will melt and become conductive, in these situations flux removal is required.

Source: Kester Solder

Solder Materials and Compounds for LEDs

August 26th, 2015


Indium Corporation provides a myriad of materials for Light Emitting Diode (LED) manufacturing. From gallium trichloride for MOCVD precursors to thermal interface materials, no other materials company provides so many solutions in so many layers of the ever-advancing LED.


LED CompoundsWe provide indium trichloride and gallium trichloride for manufacturing common MOCVD precursor materials (TMI and TMG, respectively) for LEDs.

Indium Corporation specializes in supplying IN and Ga compounds at high purity, in large volume, and around the globe.

Thermal Interface

LED Thermal InterfaceIndium Corporation is the world’s largest supplier of metal TIMs. We offer a wide selection of metal-based TIMs for reflow or compression. Our patented Heat-Spring® compressible interface material at 86W/mK conductivity can solve many thermal interface issues. The standard pack for Heat-Springs® is tape & reel and it is designed for both automated or hand assembly applications.

Our TIMs are used like a standard thermal pad. They have no residue and zero outgassing properties. Heat-Springs® are provided in custom or standard off-the-shelf shapes.

Surface Mount Assembly and Solder Fortification

LED Surface Mount Assembly and Solder FortificationIndium solder pastes for LED deliver ultra-low voiding and clear residues.

  • L-220 for Pb-free (SAC305) applications
  • L-180 for Sn63 applications

Indium Corporation also provides  solder preform chips in tape & reel right off the shelf to help with solder starvation. It is easy to add bulk solder with preforms. We also provide solder preform washers and flux-coated preforms for soldering connectors to packages.

Wave Soldering Materials and Rework

LED Wave Soldering Materials and Rework

  • Sn995 and Sn63 Bar Solder
  • WF-9940 and WF-7745 (VOC Free) Wave Flux
  • Cw-207 Cored Wire—Pb and Pb-free flux-cored rework wire; clear residue; RA type flux.

Die-Attach and Fluxes

LED Die-Attach and FluxesFor LED companies needing high temperature die-attach materials,
Indium Corporation is a global provider of solder paste, wire, and high purity AuSn preforms for fluxless die-attach.

For companies in need of materials for bumping wafers or soldering pre-plated dies for flip-chip, Indium Corporation provides “semiconductor grade” solder pastes and fluxes.


Nanobond ProcessNanoBond®, a joining process using NanoFoil®, is used to bond the thermal pad on LEDs to the heat-sinking substrates. NanoBond® eliminates the need for the conventional reflow of LEDs, resulting in improved brightness and color, and extended lifetime. When combined with conventional assembly techniques, NanoBond® produces superior thermal performances as compared to thermal epoxies.

NanoFoil® is a self-contained, localized heat source that can be used to solder bond electronics packages to substrate materials. NanoFoil® is a RoHS compliant material consisting of hundreds of alternating nanoscale layers of aluminum and nickel. Once activated, the heat can melt adjacent solder layers to join components together with minimal thermal exposure of the components.

Source: Indium Corporation

Electronics Assembly

August 21st, 2015

Rework and Touch-Up

August 21st, 2015

Indium Corporation manufactures a variety of materials for PCB rework, repair, and touch up, including flux-cored wire, liquid rework fluxes, and TACFluxes®.

Flux Cored Wire

Pb-Free SAC wireIndium Corporation has developed a range of flux-cored wire solutions to meet the needs of virtually every electronic assembly and rework operation from no-clean flux-cored wire for circuit board assembly to activated flux-cored wire for non-sensitive electronics and electrical applications.

No-clean fluxes include:

  • CW-807 halogen free for high reliability assemblies
  • CW-807M, which has a small addition of halogen activator for more difficult to solder assemblies
  • CW-807H for high temperature alloys
  • CW-501 is rosin (colophony) free and shows exceptional soldering on a wide range of assemblies
  • CW-802 is recommended only when no halogen is a must and the process is well-controlled

Activated fluxes include:

  • CW-201, a traditional RA type flux as defined by the legacy Mil-Spec QQ-S-571
  • CW-207 formulated using a blend of heat stable clear rosins
  • CW-209, which has twice the amount of halogen activator as CW-207
  • CW-501, rosin (colophony) free and has exceptionally effective soldering on a wide range of assemblies

Liquid Rework Fluxes

Flux PensLiquid rework fluxes are packaged in convenient pen dispensers, providing the optimal fluxing with no waste. Flux pens utilize a spring-loaded applicator tip to deliver a controlled amount of flux to the work surface. The user friendly pin-point application is deal for touch-up and light assembly work. Liquid fluxes include:

  • FP-500, a halogen-free flux that is compatible with both SnPb and Pb-free assemblies
  • NC-771, a halogen-free, low-residue, all-purpose flux that passes the SIR test in the un-reflowed state
  • FP-300, a water-soluble flux that is compatible with both SnPb and Pb-free assemblies


TACFluxTACFluxes® have a variety of uses including rework and repair of various electronics assemblies and components, SMT component attach (including BGAs and flip-chips), BGA ball attach, preform soldering, and virtually any application where flux is required. Indium Corporation manufactures a complete line of TACFlux®, which include no-clean, water-wash, and RMA-based fluxes.

Some of the most common TACFluxes® include:

  • TacFlux 089: no-clean flux for Pb-free alloys
  • TacFlux 089HF: a halogen-free, no-clean flux for Pb-free alloys
  • TacFlux 025: a water-soluble flux for Pb-free and SnPb alloys
  • TacFlux 020B: a halogen-free, no-clean flux for Pb-free alloy

Source: Indium Corporation, Clinton, NY