Technical Library | 2007-08-16 13:34:31.0
While experienced inspectors may be able to determine the aesthetic differences between a lead-free PCB assembly and a tin-lead version, one cannot rely on the "experienced eye". "Less wetting out to the pad edges" (Figure A) and "graininess and lack of shininess of the solder joint" (Figure B) are typical comments about some lead-free solder joints. However, in cases where a Nitrogen atmosphere was present during the reflow of the solder joint (Figure C), there will be little visual differences between the lead free alloys and their tin-lead counterparts.
Technical Library | 2016-11-08 16:47:18.0
Over time most PCB designs need to change – a mistake is found, or a part becomes obsolete, etc. Typically once the changes are complete, a new set of manufacturing files (Gerbers, NC Drill files, BOM, Pick and Place, etc) are generated, and the updated design is stored as separate version within a version control system. Using a version control system makes it possible for design teams to go back later and compare differences between design versions. ****** http://www.numericalinnovations.com/blogs/news/gerber-comparisons-between-revisions-of-the-same-board *****
Technical Library | 1999-08-05 10:27:43.0
This document is an update to the 1994 Quality and Reliability Roadmap issued in support of the 1994 National Technology Roadmap for Semiconductors. This report revisits the challenges, constraints, priorities, and research needs pertaining to quality and reliability issues. It also provides key project proposals that must be implemented to address concerns about reliability attainment and defect learning. An expanded section on test-to-test, diagnostics, and failure analysis; an edited version of the Product Analysis Forum Roadmap; and an appendix containing a draft report highlighting reliability issues is included.
Technical Library | 2017-03-15 22:35:41.0
In 2012, The European Directive on Reduction of Hazardous Substances was recast. The new version of the directive now requires products to be adequately validated as RoHS compliant in order to be eligible for CE marking and access to the EU market (...)This paper starts by reviewing the evolution of the RoHS directive and how it has evolved. It then moves on to cover the requirements and scope of the directive, as well as which standards are used to demonstrate compliance, and how those standards must be referenced in internal company quality processes.
Technical Library | 2018-04-25 15:54:52.0
An automotive wire harness rarely has just a single part number that can be ordered and installed in a vehicle. Typically, there are many different versions of the same harness based on the orderable content in the vehicle. These versions (often called harness levels) will have unique part numbers. The quantity of these levels and their content is what is typically called complexity and it has a significant impact on the cost of the harness.Quantifying these costs is often very difficult especially with manual methods of deriving and costing the complexity solution. Therefore, traditionally, harness costing has focused on the piece cost of each harness level. When these complexity related costs are considered it is typically with overly simplified cost modeling techniques.This paper will focus on the quantification of these complexity related costs so that they can be modeled allowing automated algorithms to optimize for these costs. A number of real world examples will be provided as well. Since no two businesses are alike, it is the aim of this paper to provide the foundational knowledge and methodology so the reader can assess their own business to model how variation complexity costs affect their business.
Technical Library | 2015-06-04 19:10:47.0
Integrators and designers of high-reliability systems exert little or no control over component-level plating processes that affect the propensity for tin whiskering. Challenges of how to assure long-term reliability, while continuing to use COTS parts plated with pure tin, continue to arise. An integrated, quantitative, standardized methodology is proposed whereby mitigation levels can be selected that are appropriate for specific applications of pure tin for given end-uses. A system of hardware end-use classification is proposed, together with recommended appropriate risk mitigation approaches. An updated version of the application-specific risk assessment algorithm is presented together with recommended thresholds for acceptability within the context of the hardware classifications.
Technical Library | 2017-06-22 17:11:53.0
C-mode scanning acoustic microscopy (C-SAM) is a non-destructive inspection technique showing the internal features of a specimen by ultrasound. The C-SAM is the preferred method for finding “air gaps” such as delamination, cracks, voids, and porosity. This paper presents evaluations performed on various advanced packages/assemblies especially flip-chip die version of ball grid array/column grid array (BGA/CGA) using C-SAM equipment. For comparison, representative x-ray images of the assemblies were also gathered to show key defect detection features of the two non-destructive techniques.
Technical Library | 2021-12-21 23:01:30.0
High density PWB (printed wiring board) with microvia technology is required for implementation of high density and high I/O area array packages (AAP). COTS (commercial off-the-shelf) AAP packaging technologies in high reliability versions with 1.27 mm pitch are now being considered for use in a number of NASA systems including the Space Shuttle and Mars Rovers. NASA functional system designs are requiring ever more denser AAP packages and board features, making board microvia technology very attractive for effectively routing a large number of package inputs/outputs.
Technical Library | 2013-03-14 17:19:28.0
Commercial-off-the-shelf ball/column grid array packaging (COTS BGA/CGA) technologies in high reliability versions are now being considered for use in a number of National Aeronautics and Space Administration (NASA) electronic systems. Understanding the process and quality assurance (QA) indicators for reliability are important for low-risk insertion of these advanced electronic packages. This talk briefly discusses an overview of packaging trends for area array packages from wire bond to flip-chip ball grid array (FCBGA) as well as column grid array (CGA). It then presents test data including manufacturing and assembly board-level reliability for FCBGA packages with 1704 I/Os and 1-mm pitch, fine pitch BGA (FPBGA) with 432 I/Os and 0.4-mm pitch, and PBGA with 676 I/Os and 1.0-mm pitch packages. First published in the 2012 IPC APEX EXPO technical conference proceedings.
Technical Library | 2018-05-09 22:15:29.0
Creep corrosion on printed circuit boards (PCBs) is the corrosion of copper metallization and the spreading of the copper corrosion products across the PCB surfaces to the extent that they may electrically short circuit neighboring features on the PCB. The iNEMI technical subcommittee on creep corrosion has developed a flowers-of-sulfur (FOS) based test that is sufficiently well developed for consideration as an industry standard qualification test for creep corrosion. This paper will address the important question of how relative humidity affects creep corrosion. A creep corrosion tendency that is inversely proportional to relative humidity may allow data center administrators to eliminate creep corrosion simply by controlling the relative humidity in the data center,thus, avoiding the high cost of gas-phase filtration of gaseous contamination. The creep corrosion relative humidity dependence will be studied using a modified version of the iNEMI FOS test chamber. The design modification allows the achievement of relative humidity as low as 15% in the presence of the chlorine-releasing bleach aqueous solution. The paper will report on the dependence of creep corrosion on humidity in the 15 to 80% relative humidity range by testing ENIG (gold on electroless nickel), ImAg (immersion silver) and OSP (organic surface preservative) finished PCBs, soldered with organic acid flux.
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