Papers by Timothy Jensen
by Gordon Clark, Renee Michalkiewicz, Timothy Jensen , Brian Toleno, Jasbir Bath
Over the last few years, there has been an increase in the evaluation and use of halogen-free soldering materials. In addition, there has been increased scrutiny into the level of halogens and refinement of the definition and testing of halogen-free soldering materials. The challenge has been that there has been no common standard across the industry in terms of halogen-free definitions and the corresponding test methods to determine these. This has created confusion in the industry as to what end users want and what soldering materials suppliers can actually provide. This paper will review the status of both halogen-free and halide-free in terms of definitions, test methods and the limitations and accuracy of test methods used to determine if a soldering material is halogen/halide-free or not. For halogen-free and halide-free definitions, the paper will review the different industry standards which are currently available and those being drafted, and it will discuss any similarities and differences. It will also cover the origins of some of the definitions mentioned in the standards. The paper will include a review of the accuracy and limitations of several test methods and preparation techniques for halogen and halide determination.
Apex 2011, soldering materials, halides, halogen-free
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Posted on 11 Apr 2011
by Timothy Jensen , Dr. Ronald C. Lasky
The clock is ticking, on July 1, 2006 the WEEE Initiative will take effect. Thereafter, all electronic assemblers that sell products in Europe must be ready to convert their assembly processes to
Pb-free . The nearness of this date raises the question of what can be done to get ready. In response to this need, we will review a pioneering effort in establishing a Pb-free process.
pb-free, lead-free, WEEE, RoHS
[Permanent Link to this Paper ]
Posted on 4 Mar 2010
by Timothy Jensen , Dr. Ronald C. Lasky
Chinese version of Challenges of Implementing a
Halogen-Free PCB Assembly Process.
oxidation barrier, activator, pb-free, reflow, graping, head-in-pillow, halide-free, halogen-free, halogens, CHINESE LANGUAGE
[Permanent Link to this Paper ]
Posted on 22 Mar 2010
by Dr. Ronald C. Lasky , Timothy Jensen
The electronics industry continues to strive to provide more environmentally friendly products. This movement is partly due to legislation from various countries, partly due to public outcry from well publicized 3rd world recycling practices, and partly due to non-government organizations (NGOs) testing and publishing information on electronic devices regarding their content of various toxic materials. One set of materials targeted for reduction and eventual elimination are halogenated compounds. Halogens are found in plastics for cables and housings, board laminate materials, components, and soldering fluxes. Replacing these halogenated compounds can have a dramatic affect on the PCB
assembly process. In this paper those challenges will be discussed as well as techniques and practices that will help ensure high end of line yields and continued reliability.
oxidation barrier, activator, pb-free, reflow, graping, head-in-pillow, halide-free, halogen-free, halogens
[Permanent Link to this Paper ]
Posted on 4 Mar 2010
by Timothy Jensen , Dr. Ronald C. Lasky
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Challenges for Implementing a Halogen-Free Process
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The drive to produce halogen-free electronics has grown significantly, driven partly by legislation and partly by environmentalist organizations. This paper will discuss the challenges of implementing such a halogen-free assembly process. It will start by briefly discussing the reasons that “halogen-free” is with us. The PCB materials that might contain halogens will then be presented. PWB and component concerns will be briefly reviewed. The bulk of the paper will center on the process development issues in establishing a halogen-free assembly process, including solder paste evaluation and selection, solder fluxes, the SMT stencil printing process, reflow and test. Comparisons between halogen containing and halogen-free solder pastes regarding their process performance and reliability will also be presented. The paper will close with a brief review of techniques to analyze halogen content in materials and some of the pitfalls if inappropriate tests are used.
halogen-free
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Posted on 11 May 2009
by Chris Anglin, Dr. Ronald C. Lasky , Ed Briggs , Timothy Jensen
The explosive growth of personal electronic devices, such as mobile phones and personal music devices, have driven the need for smaller and smaller active and passive electrical components. Not too long ago, 0401 (40 x 10 mils) passives were seen as the ultimate in miniaturization, but recently 0201 and now 01005 passives have arrived, with rumors of even smaller sizes to come. For active components, the 30 mil CSP (a chip scale package with the solder balls on 30 mil (0.75mm) centers) has become virtually a requirement for enabling the many features in modern portable electronic devices. The more than 1 billion mobile phones assembled in 2008 will use the lion’s share of the 12 billion or so CSPs concurrently manufactured.
This miniaturization trend occurring at the same time as the conversion to RoHS compliant lead-free assembly has put a considerable strain on the electronic assembly industry. This paper will discuss some of these challenges and the work that has been performed to mitigate them. Among the challenges discussed are stencil printing the small features and obtaining consistent volume in the printed solder paste deposit, minimizing the oxidation of the solder powder in the small deposit during reflow, and assuring a good finished solder joint after the reflow process.
area ratio, Print Study, Fine Powders
[Permanent Link to this Paper ]
Posted on 4 Mar 2010
by Timothy Jensen
Chinese version of Head-In-Pillow: The Defect that Caught Us Napping.
head-in-pillow, CHINESE LANGUAGE
[Permanent Link to this Paper ]
Posted on 22 Mar 2010
by Timothy Jensen
Although the head-in-pillow defect is not totally new, the high frequency of occurrence is. This defect is a direct result of the convergence of product miniaturization and the transition to
Pb-free solders .
head-in-pillow
[Permanent Link to this Paper ]
Posted on 4 Mar 2010
by Timothy Jensen , Dr. Ronald C. Lasky
lead-free, pb-free
[Permanent Link to this Paper ]
Posted on 31 Mar 2010
by Harish Gadepalli, Rangaraj Dhanasekaran, Dr. S. Manian Ramkumar, Timothy Jensen , Ed Briggs
Quad Flatpack No lead (QFN) packages have become a popular choice in electronics packaging due to its small form factor. They are also gaining rapid industry acceptance because of its excellent thermal and electrical performance. The bottom side of the QFN package has a large thermal pad. This exposed die attach pad effectively conducts heat to the PCB and also provides a stable ground connection. Effective soldering of this surface to the pad on the PCB is required for good thermal dissipation and component functionality. The exposed thermal pad presents various challenges during the surface mount assembly process. One major challenge is solder void formation. Voids are primarily formed due to the entrapment of volatiles in flux outgassing during the reflow process.
The primary objective of this study is to determine optimal parameters to minimize void formation in QFN packages (QFN16 and QFN20), specifically the reflow profile, leadfree solder paste and stencil aperture opening for the thermal pad. A systematic DOE based approach was used to arrive at conclusions, using the ratio of void volume on the thermal pad to the actual volume of solder paste printed as the response variable. Various graphs are presented to understand the impact of different parameters. Interaction graphs were used to determine optimal settings for each parameter.
reflow profile, lead-free, voiding, solder paste
[Permanent Link to this Paper ]
Posted on 21 Jan 2011
by Timothy Jensen
As the July 1, 2006 Pb-free deadline approaches, many electronics assemblers are beginning to fathom the changes and process demands required. The two biggest material concerns involve solder paste and components. This document provides practical recommendations for evaluating Pb-free solder pastes and ensuring that the selected solder paste will deliver assembly yields comparable to, or better than, the incumbent Sn/Pb solder paste.
lead-free, pb-free, stencil printing, reflow, response to pause, evaluation, solder paste
[Permanent Link to this Paper ]
Posted on 1 Jan 2009
by Amanda Hartnett , Dr. Ronald C. Lasky , Timothy Jensen
Chinese version of Soldering Challenges in a Halogen-Free PCB Assembly Process
halogen-free, halide-free, solder, soldering, graping, flux, head-in-pillow, hole-fill, CHINESE LANGUAGE
[Permanent Link to this Paper ]
Posted on 13 May 2011
by Timothy Jensen , Dr. Ronald C. Lasky , Amanda Hartnett
Flame retardants have played an important role in the safety of many products. It is safe to say that thousands of lives have been saved by flame retardants. Flame retardants are used in products as varied as children's pajamas to electronics assemblies. Some of the more successful flame retardants are halogenated compounds. Halogenated materials are found in polyvinyl chloride (PVC), brominated flame retardants (BFRs), chlorinated flame retardants (CFRs), as well as in fluxes used in the electronics assembly industry. Product does not contain any halogenated compounds. However, that is not exactly how the term is used for soldering fluxes. A flux that is classified as
halide-free by the IPC/J-STD-004 is actually only free of ionic halides.
hole-fill, head-in-pillow, flux, graping, soldering, solder, halide-free, halogen-free
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Posted on 10 Mar 2010
by Timothy Jensen
As small surface-mount components such as 0201 and 01005 packages have entered volume assembly, manufacturers are observing increased instances of poor solder coalescence during reflow. The root cause is the change in oxidation behavior at very low volumes of deposited paste. A solution is required, both to restore a high-quality appearance to solder joints and to maintain customer confidence. Comprehensive analysis of factors including material selection, print process settings, reflow profile, and factory-floor practices highlights a number of measures that engineers may apply to solve this issue cost- effectively without impairing satisfactory reflow of other components on the board.
solder paste, pb-free, lead-free, electronics assembly, graping
[Permanent Link to this Paper ]
Posted on 10 Mar 2010
by Eric Bastow , Timothy Jensen
The advent of the EU’s RoHS law has encouraged a significant amount of research to find an alloy, for electronic assembly that will satisfy RoHS’s lead-free requirement and have optimum process ability and field reliability. The resulting research, much of it lead by iNEMI, resulted in the near eutectic tin-silver-copper alloy SAC387 (Sn95.5Ag3.8Cu0.7) as an initial favorite to fill this need in the early 2000s. By 2004 or so, many people were using SAC305, partially because of its greater resistance to tombstoning. It appeared that SAC305 would become the de-facto lead-free standard alloy for RoHS compliant electronic assembly. However, with the dramatic increase in silver prices in the last few years, SAC105, having 2% less silver was being evaluated and used for its obvious cost savings. Reliability testing of SAC105 also showed that although it did not perform as well as SAC305 in thermal fatigue cycle testing, it was better than SAC305 in drop shock tests. The explosive growth of mobile phone sales, over 1 billion per year, made SAC105’s superior drop shock performance attractive for these and other portable devices.
In addition to research relating to SAC305 and SAC105, much work has been performed on the study of the effects of small quantities (<0.1%) of alloying metals on lead-free alloys’ process ability and reliability performance. These "dopants" can dramatically affect an alloy’s performance.
All of the above work has resulted in what many are calling lead-free alloy proliferation as more and more alloys are being considered for implementation. This proliferation drives up solder paste cost as manufacturers cannot achieve economies of scale. In addition, with so many alloys to consider, it is difficult for researchers to develop extensive data bases of process and reliability performance.
This paper is an overview of this lead-free alloy proliferation and an outlook on how alloy convergence might occur.
solder, SAC, pb-free, dopants, Reliability, thermal cycling, drop testing
[Permanent Link to this Paper ]
Posted on 15 Oct 2009
