Technical Library | 2015-04-29 03:29:56.0
Statistical Appearance Modelling technology enables an AOI system to “learn real world variation” based on operator interaction with inspection task results. This provides an accurate statistical description of normal variation in a product. With modelling technology, the user does not have to anticipate potential defects as the system will “flag” anything outside the “normal production range”. And, since the system is programmed with real production variation, it is sensitive to small subtle changes enabling reliable defect detection. Autonomous prediction of process variation enables an AOI system to be set up from a single PCB with production-ready performance. Setup time can be
Technical Library | 2020-03-19 00:23:15.0
In this study, the question was how to perform statistically reliable robust- ness tests for the non-contact drop-on-demand printing of functional fluids, such as solder paste and conductive adhesives. The goal of this study was to develop a general method for hypothesis testing when robustness tests are performed. The main problem was to determine if there was a statistical difference between two means or proportions of jet printing devices. In this study, an example of jetting quality variation was used when comparing two jet printing ejector types that differ slightly in design. We wanted to understand if the difference in ejector design can impact jetting quality by performing robustness tests. and thus answer the question, "Can jetting differences be seen between ejector design 1 and design 2"?
Technical Library | 2007-05-17 16:44:37.0
In the quest for quality, selecting the right Statistical Process Control (SPC) Software system doesn't boil down to a simple functional "fit-to-requirements" anymore. Once the expert domain of highly focused, independent software developers, the competitive landscape has changed dramatically with the influx of big-name ERP software providers who are aggressively promoting integrated quality modules within an all-encompassing business application framework.
Technical Library | 2010-04-22 14:55:51.0
It is now widely accepted that using designed experiments is the most effective way to optimize surface mount technology (SMT) processes. This situation begs the question "what is an effective strategy in implementing this powerful tool?" This paper will present such a strategy that incorporates Taguchi's approach for screening, full factorial analysis for optimization and central composite design for precise modeling. We will present these techniques using MINITABTM Release 13 statistical software and printed circuit board industry applications.
Technical Library | 2010-08-05 18:39:39.0
Variability analysis is important in successfully deploying multi-gigabit backplane printed wiring boards (PWBs) with growing numbers of high-speed SerDes links. We discuss the need for large sample sizes to obtain accurate variability estimates of SI me
Technical Library | 2007-11-29 17:20:31.0
Programs have been developed to predict the expected yield of flip chip assemblies, based on substrate design and the statistics of actual manufactured boards, as well as placement machine accuracy, variations in bump sizes, and possible substrate warpage. These predictions and the trends they reveal can be used to direct changes in design so that defect levels will fall below the acceptable limits. Shapes of joints are calculated analytically, or when this is not possible, numerically by means of a public domain program called Surface Evolver. The method is illustrated with an example involving the substrate for a flip chip BGA.
Technical Library | 2021-07-27 14:57:18.0
It should be noted that this is an overview paper that represents the early stages of an ongoing investigation into the causes and effects between conductive anodic filament (CAF) formation and printed wiring board (PWB) material damage. Our belief is that certain or specific types of material damage can increase the propensity for CAF formation. The preliminary data collected suggests is that there is no statistical correlation between the general definition of material damage (cohesive failure) and CAF. The resulting dichotomy is that we find no CAF failures in some coupons that have obvious material damage and we find CAF failures in coupons that don't exhibit material damage.
Technical Library | 2014-07-31 16:36:59.0
Metal whiskers often grow across leads of electric equipment and electronic package causing current leakage or short circuits and raising significant reliability issues. The nature of metal whiskers remains a mystery after several decades of research. Here, the existence of metal whiskers is attributed to the energy gain due to electrostatic polarization of metal filaments in the electric field. The field is induced by surface imperfections: contaminations, oxide states, grain boundaries, etc. A proposed theory provides closed form expressions and quantitative estimates for the whisker nucleation and growth rates, explains the range of whisker parameters and effects of external biasing, and predicts statistical distribution of their lengths.
Technical Library | 2023-08-02 18:18:23.0
As six sigma (6) and better processes are demanded for higher yields and as organizations move from measuring defects in terms of parts-per-million (ppm) towards parts-per-billion (ppb), the resolution of extant control charts is becoming insufficient to monitor process quality. This work describes the development of a new statistical process control (SPC) chart that is used to monitor processes in terms of defects-per-billion-opportunities (dpbo). A logical extension of the defects-per-million-opportunities (dpmo) control chart, calculations used to derive the dpbo control limits will be presented and examples of in-control and out-of-control processes will be offered.
Technical Library | 2008-12-03 19:39:00.0
This paper presents the analysis from a recent printing study employing a test vehicle that includes components such as 01005s to QFPs. In a recent publication, part of this study was presented focusing on 01005 printing only. This printing process was determined to be suitable for 01005s assembly and also analyzed based on statistical capability. The current paper will present the results from additional detailed analysis to determine if this process has the capability to provide sufficient solder paste deposits for larger components located on the same test board. In the future, the SMT industry may always look towards “Broadband Printing” as an alternative to dual stencil or stepped stencil printing technologies in order to meet the needs of both small and large components.
