Papers by Chris Anglin
by Chris Anglin
The purpose of a solder paste print evaluation is to observe variation in transfer efficiency to the assembly process under conditions that permit careful scrutiny.
Alternative purchasing decisions and process selection reveal various methods of analysis for scrutinizing the solder paste print activity. Many of these methods are based on the assumption that all of the root causes for paste transfer efficiency during paste print trials are known and certain. However, in most cases the amount and timing of these transfer efficiencies are estimated, and uncertainties exist in the estimation process. Furthermore, there is typically much uncertainty with stencil aperture area ratio, and area ratio factors inevitably affect the purchasing criteria more than others. Thus, the printed circuit board assembly industry needs additional analysis techniques for paste evaluation in order to get explicit information on the effects of uncertainties in the stencil aperture area ratio is important.
solder paste, area ratio
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Posted on 21 Jan 2011
by S. Manian Ramkumar Ph.D., Rita Mohanty Ph.D., CEMA, Chris Anglin, Toshitake Oda
The demand for product miniaturization, especially in the handheld device
area, continues to challenge board assembly industry. The desire to incorporate
more functionality while making the product smaller continues to push board
design to its limit. It is not uncommon to find boards with castle like components
right next to miniature components. This type of board poses special
challenge to the board assemblers as it requires wide range of paste volume
to satisfy both small and large components. One way to address the printing
challenge is to use creative stencil design to meet the solder paste requirement
for both large and small components. Example of stencil design includes step
stencil, dual printing, over size aperture, etc. Stencil printing process at its
most basic level involves pushing solder paste through a stencil (with various
size apertures) by a squeegee blade. As the squeegee blade and the stencil
are in constant contact with the paste during the printing process, their surface
characteristics play an important role in the printing process. The most
important attribute of a stencil is its release characteristic. In other word, how
well the paste releases from the aperture. The paste release in turn depends on
the surface characteristics of the aperture wall and stencil foil surface. Recent
introduction of a new technology, Nano-coating for both stencil and squeegee
blades, has drawn the attention of many researchers. As the name implies,
Nano-coated stencils and blades are made by conventional method such as
laser cut or Electoform then coated with nano functional material to alter the
surface characteristics. This study will evaluate nano-coated stencils for passive
component printing including 01005. Various print experiments will be
conducted using different stencil technology, stencil thicknesses, aperture size,
aperture orientation, aperture shapes, and selected paste type with optimal
print parameters, to understand the effect of chosen factors on the print quality.
Print quality will be determined by visual inspection and 3D measurement of
the paste deposit to understand the volume transfer efficiency.
Apex 2011, solder paste, transfer efficiency, area ratio, stencil technology, broadband printing, nano-coated stencil
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Posted on 11 Apr 2011
by Chris Anglin
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Establishing a Precision Stencil Printing Process for Miniaturized Electronics Assembly
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The advent of miniaturized electronics for mobile phones and other portable devices has required the assembly of smaller and smaller components. Currently 01005 passives and 0.3mm CSPs are some of the components that must be assembled to enable these portable electronic devices. It is widely accepted that about 65% of all end of the line defects occur in the stencil printing process. Given all of the above it is critical that a precision stencil printing process be developed to support miniaturized electronic assembly.
This paper will be a summary of a significant amount of experimental data and process optimization techniques that were employed to establish precision SMT printing process. Our results indicate that the industry standard stencil aperture aspect ratio requirement of > 0.66 is an excellent rule of thumb. However, by optimizing printer setup with vacuum support, foil-less clamps, squeegee edge guards etc and assuring cleanliness and squeegee and stencil quality, we have been able to obtain acceptable stencil printing results with area ratios of 0.5 with Type III solder pastes. The work that was performed to achieve these results will be discussed in detail in the paper.
halogen-free, solder paste, solder, solder reliability, flux, solder quality, stencil printing
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Posted on 11 May 2009
by Ed Briggs , Dr. Ronald C. Lasky , Chris Anglin
Chinese version of Fine Feature Stencil Printing 0.3MM Pitch Components
CHINESE LANGUAGE, solder paste, stencil printing, miniaturization
[Permanent Link to this Paper ]
Posted on 13 May 2011
by Chris Anglin, Dr. Ronald C. Lasky , Ed Briggs
The explosive growth of personal electronic devices such as mobile phones and personal music devices has driven the need for smaller and smaller passive and active 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 electrical components, the 0.4mm pitch component has become commonplace with 0.3mm already in the works. What effect does this miniaturization have on the stencil printing process? Can it meet the challenge? This paper takes a preliminary look at some of the work that has been performed to evaluate the capability of the stencil printing process to print these fine feature components. Discussed is the stencil printing of the small features and efforts to obtain consistent volume in the printed solder paste deposit.
miniaturization, stencil printing, solder paste
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Posted on 4 Mar 2010
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
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Posted on 4 Mar 2010
by Chris Anglin, David Sbiroli, Ed Briggs
The continual miniaturization of electronics components for personal electronics devices, coupled with the conversion to RoHS- and REACH-compliant lead-free assemblies, has put a tremendous strain on the electronics assembly industry. Introduction of 01005 passives, and active components on the order of 0.3mm pitch, initiates newly defined questions about specification limits for solder paste stencil print performance.
This paper discusses variability of solder paste print performance and its relationship to specification limits. The objective is to describe analyses to determine stencil print process character, using actual paste print measurement data. Aside from setting specification limits, application of statistical methods for the analysis of variation in stencil print performance could help understand appropriate production statistical process control (SPC) limits sought by SMT manufacturing and quality engineers from stencil print inspection results that are gathered during SMT assembly.
Effects on values of Cp and Cpk by various specification limits are presented. This discussion is based on recent application development experiments, to elucidate how average solder paste measurement and standard deviation measurement effect new print process capability challenges. From this work, a strategy to optimize a new 01005 stencil printing process is reviewed. Importantly, the discussion includes key factors with planning quality aspects of SMT assembly. SPC techniques presented will show how to measure stencil print performance capability, and result in opportunity for reduced assembly costs and increased sales income.
transfer efficiency, process capability study, capability ratio, statistical process control (SPC), control charts, stencil aperture design, pad design, solder paste, area ratio
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Posted on 24 Jan 2011
by Chris Anglin, Ed Briggs
This paper is a summary of best practices in optimizing the printing process focusing on comparison of large and small apertures, square vs. round, not with the same area ratio but with similar or the same volume. This paper will definitively clear the air on the round versus square aperture debate.
SMT, circuit board assembly, stencil apertures, solder paste, stencil printing
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Posted on 21 Jun 2011
by George Babka, David Sbiroli, Richard Brooks, Chris Anglin
With the introduction of 01005 chip components and 0.3 mm pitch CSP devices, electronic component packaging is pushing surface mount technology to the limits of its potential. Miniaturization is driving the electronics industry to implement the smallest and tightest pitch components in order to meet their customer demands. But how much miniaturization is possible before there is a paradigm shift in the technology? At what point is solder paste no longer viable? How small of a feature can be printed with solder paste, and can this process be implemented into a production environment?
Most of the factors and critical parameters in ultra-fine pitch printing have been well understood and documented for over twenty years. Some of these parameters are squeegee speed, squeegee pressure, stencil design (technology, thickness & area ratio), and solder paste. But as the pitch and aperture sizes get smaller and smaller, we begin to see that additional factors start to have an increased effect on the solder paste deposition (transfer efficiency). What are these factors and can we control them in order to obtain acceptable results for transfer efficiency and minimized variability? This paper will evaluate these additional factors and how they affect the transfer efficiency of the paste.
ultra-fine pitch printing, separation speed, stencil technology, stencil design, pad design, solder powder, tooling, solder paste, area ratio
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Posted on 15 Oct 2009
by Chris Anglin
Design development of miniaturized electronics for mobile phones and other portable devices continues to challenge the required assembly capability of smaller and smaller components. Some of the components that must soon be assembled to enable these portable electronic devices include 01005 passives and 0.3mm CSPs. In addition, it is widely accepted that about 65% of all end of the line defects occur in the stencil printing process. Given all of the above, it is critical that precision stencil printing processes be further developed to support miniaturized electronic assembly.
This paper is a summary of a sample size consideration used to collect experimental data and the process optimization techniques that are employed to establish a precision SMT printing process. Our results indicate that the industry standard stencil aperture area ratio requirement of >0.66 remains an excellent rule of thumb. However, by optimizing printer setup with custom-board recessed vacuum support, foil-less clamps, squeegee edge guards, etc., and assuring squeegee and stencil quality, we have been able to obtain acceptable stencil printing results with area ratios nearing 0.5 with Type IV solder pastes. The sample size decision tools that are employed to characterize paste performance results will be discussed in detail in the paper.
solder paste, solder paste evaluation, area ratio, stencil printing
[Permanent Link to this Paper ]
Posted on 25 Jan 2011
