Technical Articles

Conformal Coating Over No Clean

January 11, 2013
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Not All WOA (Weak Organic Acids) Are the Same

October 27, 2012
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Lead-Free Alloy Development

January 06, 2012
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Overcoming the Challenges of the QFN

September 30, 2011
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Understanding Lead-Free Alloys

September 25, 2011
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A Study of Lead-Free Solder Alloys

September 25, 2011
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Considerations for Lead-Free Wave Soldering

September 25, 2011

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A Comparison of Leading Lead-Free Alloys

September 20, 2011
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Impact of Mesh Size and Stencil Technology on Deposition Volume

February 02, 2011

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A Study of Raw Flux on PCBs

July 19, 2010

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Bar Solder Drossing Characteristics and Wave Contamination

April 21, 2010
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Considerations for Printing Lead-Free Solder Pastes

November 11, 2009

SMT printing will require reexamination and process adjustment when lead-free soldering is implemented. If a high quality solder paste is used and standard rules for SMT printing are followed, consistent stencil life, aperture release, print definition, high-speed print capabilities and print repeatability may be expected. However, implementation of lead-free solder paste does necessitate some adjustment, as well as providing an opportunity to review and fine-tune several key printing parameters.
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A Comparison of Tin-Silver-Copper Lead-Free Alloys

November 11, 2009

Tin-Silver-Copper alloys are the leading candidate lead-free substitute. However, as there are several different Tin-Silver-Copper alloys, background information is necessary to determine which alloy is best suited for the broadest range of applications. The Sn96.5/Ag3.0/Cu0.5, Sn95.5/Ag3.8/Cu0.7, and Sn95.5/Ag4.0/Cu0.5 alloys are compared for availability, cost, solder paste printing, melting, wetting, wave soldering, thermal fatigue and solder joint reliability.
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Controlling Copper Build Up In Automatic Soldering Equipment

November 11, 2009

Since “nothing solders like solder”, HAL (Hot Air Leveling) will continue to hold a significant place in the surface finishing industry. Furthermore, the wave soldering process will continue to be a viable means of electronics assembly. However, as automatic soldering processes using lead-free alloys have become increasingly prevalent, questions have arisen about copper dissolution into these alloys. The first part of this study was to determine if there is any significant difference between Sn/Ag/Cu alloys when used in automatic soldering equipment in terms of copper build-up in the system. The second part of this experiment was to determine how to effectively control copper build-up in automatic soldering equipment. Yet another issue is that there is not yet an agreed upon industry specification for lead-free pot maintenance. Clearly, this will be needed as a guideline for the users of these alloys. To accomplish this, a specification is proposed based upon these experiments.
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A Study of Lead-Free Wave Soldering

November 11, 2009
This brief study of lead-free wave soldering focuses upon copper dissolution and solder maintenance issues. Unfortunately, it is determined that waste and changeover costs can dramatically increase with lead-free wave soldering.
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Reflow Profiling: Time Above Liquidus

November 11, 2009
To ensure the long-term reliability of an electronic assembly, particular attention needs to be paid to the reflow profile. One area of the profile often questioned is the time above liquidus. If the time above liquidus is too brief, there is the risk that marginal or non-wetting will occur. At the other extreme, if the time above liquidus is too long, the integrity of the solder joint can be compromised. Furthermore, specific reflow guidelines should be followed when soldering to alternative surface finishes and/or when utilizing a non-standard solder alloy.
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A Practical Guide to Achieving Lead-Free Electronics Assembly

November 11, 2009

To successfully achieve lead-free electronics assembly, each participant in the manufacturing process, from purchasing to engineering to maintenance to Quality/Inspection, must have a solid understanding of the changes required of them. This pertains to considerations regarding design, components, PWBs, solder alloys, fluxes, printing, reflow, wave soldering, rework, cleaning, equipment wear & tear and inspection.
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Specialty Solders: A Study of Indium/Lead

November 11, 2009
More complicated electronics will require the increased use of specialty solders. Specialty solders, such as indium alloys, offer advantages for gold soldering, step soldering and fatigue resisatnce.
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Head-in-Pillow BGA Defects

November 11, 2009
Head-in-Pillow (HiP) solder joints have become a more prevalent defect as the industry continues to migrate to more lead-free assemblies. This defect occurs when an electronic and mechanical bond is not made between BGA solder spheres and the solder paste during reflow. Perhaps a larger problem may be that this defect can make it through both x-ray inspection and in-circuit testing undetected, only to surface in the field as the result of thermal and mechanical stress. Also complicating the situation are changes in solder sphere to low silver alloys with or without dopants for improved shock resistance. New surface oxides may be more difficult for current solder paste technologies to overcome and facilitate reliable solder joint formation.
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Halogen-Free Assemblies Testing

November 11, 2009
The increased interest in halogen-free assemblies is a result of Non-Government Organizations (NGOs) exerting pressure on electronic equipment manufacturers to eliminate halogens. The NGOs primary focus is on resolving global environmental issues and concerns. As a result of an increase in the enormous “e-waste” dump sites that have begun showing up around the world, NGOs are pushing consumer electronic manufacturers to ban halogen-containing material in order to produce “green” products. Not only are these sites enormous, but the recycling methods are archaic and sometimes even illegal. This stockpiling and dumping has created growing political and environmental issues. In order to deal with this issue, the question of why halogens are a focal point must be addressed.
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