The RoHS legislation in Europe has far reaching consequences,which necessitates a change in lead coating on component leads. Although some suppliers are using a tin finish,there is a tendency for pure tin plating to form whiskers over time which can cause failure of the circuit. To prevent the formation of whiskers different companies have designed different plating schemes and used different materials. Industry has yet to standardize on a lead finish to replace the Sn:Pb solder used in the past.
This paper examines several different lead materials before and after exposure to tin whisker promoting environments to determine the effects of those environments on the soldered connection. In addition to promoting the growth of tin whiskers,these stressful environments also age the solder connections. Based on components used in the telecom industry,solder connections are examined for the presence of tin whiskers,grain structure,intermetallic formation and cracking after being temperature cycled (-40C to 85C) and soaked at 50C and 85% RH.

The whisker concern has been greatly affecting lead free RoHS conversion confidence in the lead frame packages,particularly for high end product conversion. Although plenty of related study in E4 and iNEMI have directed standard whisker testing conditions and measurement methods,the practical whisker performance data in service life is still very small due to numerous extra factors involved from surface mounting and waving soldering.
Most of the literature on Tin (Sn) whiskers study are test results based at the component level in storage or reflow preconditioning to simulate backward and forward conversion in service life. However,for practical Sn-whisker issues,it is
necessary to consider the entire structure,i.e.,the component characteristics,solder joint,PCB and process effect. In this study,matt Sn plated packages with Cu and Alloy 42 based in PLCC,PDIP,LQFP and TSOP were subject to lead free
surface mounting and wave soldering on PCBs with OSP surface finish,followed by TCT (-55 to 85?) 1000 cycle,THT (60?/90%RH) 3000hrs and ambient condition 3000hrs to investigate whisker growth propensity. Whisker growth on the PCB after reflow simulation and separate from the component level was examined to understand whether the whisker risk will be reduced or raised because of factors such as the matt Sn structure,lead frame base,reflow profile and solder paste wetting behavior. Furthermore,SnPb and SnBi plated 4 types of the same package types as above were used as controls for whisker growth comparison. Additionally,corrosion phenomenon due to higher temperature THT testing to correlate to whisker growth after the surface mounting condition will be explored with FIB analysis as well.

Transitioning to offshore sourcing has become a seductive argument for cost reduction. Most managers agree that the impact has been beneficial to the consumer and the trading conglomerates. This paper addresses public perceptions,structural issues,geopolitical and demographic factors that fuel the offshore sourcing argument. It addresses design,marketing,sourcing,and
logistics,local and cultural idiosyncrasies of offshore sourcing that assures a successful venture.

Copyright,like all other forms of intellectual property,is based on negative rights. A copyright registrant may exclude others from reproducing a given copyrighted work,composing a derivative work,performing the work publicly,distributing the work (including sale,lease,or rental of the work),or displaying the work. Works that may be protected by copyright include literary works; musical works and accompanying words; audiovisual works,including motion pictures; sculptural works; pictorial,graphic and architectural works; sound recordings; and,pantomimes and audiovisual works.
The power of copyright is especially effective in preventing the rote copying of a work. A work is a fixed,complete form of authorship. To be complete,a work must have all of its component parts. A computer program which does not run and has no utility is a good example of an incomplete project that is not a work. Direct copying is the easiest form of copyright infringement activity to prevent. However,the test in copyright is one of substantial similarity. Whether a copied work is substantially similar to the copyrighted work is a question of fact to be decided by a jury.

The challenge manufactures face when competing in the world marketplace is to offer a product that will meet all performance and functionality expectations without increasing product size or cost. Increased electronic functionality can be
achieved through the development of more complex silicon integration but that route generally requires a great deal of capital resources and an excessive amount of time. Multiple-die package concepts are often proving superior to the system-on-chip alternative because it minimizes risk and has the potential for economically integrating several different but complementary functions. The information presented in this paper will review several existing package-on-package configurations and introduce a new substrate fabrication process developed to improve IC package density and circuit routing efficiency. In
addition,the basic package assembly methodology will be described and examples of high density stacked memory and mixed function variations shown. In keeping with IPC presentation guidelines it should be noted that a portion of the technical information presented focuses on unique fabrication processes developed for the substrate and are a licensed technology covered by several US and foreign patents.

In this paper,factors that influence the ability for a flex circuit,especially a multilayer flex circuit,to survive the lead-free soldering and other thermal processes during the circuit fabrication processes will be discussed. Results and discussion will be given to demonstrate that the main factors that determine the robustness of a multilayer flex circuit to survive lead-free soldering include: (a) the intrinsic thermal stability of the flex circuit materials used to build the circuit; (b) the multilayer construction of the circuit and related processes making it; and (c) the design of the circuit patterns.

We present the electrical characterization of our Liquid Crystal Polymer (LCP) at microwave and millimeter frequencies and the applications of LCP to circuit components. We use several methodologies to determine the electrical characteristics of LCP for microwave and millimeter wave frequencies. Cavity resonators [1],micro strip T-resonators [2],and micro strip ring resonators [1,3] are measured in order to characterize both the dielectric constant and loss tangent up to 40GHz. The measured dielectric constant is shown to be steady near 3.0,and the loss tangent stays below 0.002,which is better than
advanced polyimide materials. Furthermore,micro strip lines are designed and fabricated on both LCP substrate and other conventional materials in order to compare loss characteristics. The measured insertion of micro strip lines on a LCP
substrate (25µm) and a polyimide substrate (25µm) is 0.11dB/mm and 0.18dB/mm,respectively. These results show that LCP has excellent and stable dielectric properties at high frequencies and the data suggests that this material can be used for applications extending through millimeter wave frequencies. LCP’s inherent properties such as multi-layer capabilities,excellent electrical properties,flexibility,and near hermetic nature suit it to a wide range of applications such as passive devices,packages,and RF cables. Finally,we demonstrate the development of a ban pass filter on LCP flex to achieve an
insertion loss less than 1 dB at 6 GHz in the pass band. The microwave characteristics of LCP have provided the feasibility of this material for low cost and high performance substrates for microwave and millimeter wave applications.

The data from the IPC Alternate Finishes Task Group Report “Time,Temperature and Humidity Stress for Final Finish Board Solderability” has been analyzed in a greater depth than in the actual report or a subsequent paper. Thermodynamically-based equations have been developed that are a better fit for the data than the intuitive ordering of the data in the report. Equations for the solderability results for the immersion silver,immersion tin,reflowed tin/lead,OSP and ENIG and the bare copper finishes studied in the IPC report are included here.

Organic Solderability Preservatives (OSP) continue to attract significant attention as circuit board final finishes. They have evolved from simple and thin benzotriazole coatings to thicker and more complex substituted imidazole and benzimidazole based films. The driver for these changes is the demand for better protection of the copper surface,which is strengthened further by the harsh demands of Pb-free processing. Better protection of the copper surface is effected by a more thermally robust active ingredient: the organic compound. The thermal properties of the organic compound,though,are not the only
characteristic of a good OSP coating. This paper attempts to describe the structure and composition of the organic film as well as the influence of the OSP coating process on achieving optimum performance in a Pb-free environment.

This paper analyzes the differences in plated through hole fill performance between the regular OSP and Pb-free OSP PCB surface finish chemistries in a Pb-free wave solder process. The variables studied include two board thicknesses - 93mil and 125mil,three hole sizes - pin plus 16,24 and 40mils,internal Cu layer connections - single and three plane layer connections,two pin shapes - circular and rectangular and two reflow atmospheric preconditions - Nitrogen and Air. A SnPb control was included for the 93mil thick test board. The bare PCBs were initially subjected to 220oC and 240oC peak reflow process twice for the SnPb and Pb-free wave soldering samples,respectively. This was followed by a wash process before wave soldering.
The Pb-free wave soldering results indicated that the Pb-free OSP performed better than the regular OSP chemistry by 15% under air and 40% under nitrogen reflow preconditioning. In Pb-free wave soldering,the air preconditioning resulted in better hole fill than nitrogen. Board to board variation of hole fill was much lower in the Pb-free OSP chemistry compared to regular OSP. Plated through hole size of 40mils and 16mils,larger than the pin diameter proved to be best and worst designs for the 125mil PCB,respectively. The SnPb control almost had greater than 92% average hole fill for every design variable in this experiment.
Overall,the results indicated that the regular OSP chemistry in Pb-free wave soldering failed to meet the 50% hole fill required per IPC-A-610,for all the conditions studied. The 125mil thick PCB using Pb-free OSP chemistry also failed to meet the IPC requirements for all the conditions evaluated. However,the 93mil thick PCB using Pb-free OSP chemistry was able to meet this 50% hole fill requirement(although not meeting the general 75% minimum requirement),except when the hole diameter is 16mils larger than the pin.