Papers about stencil printing
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
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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 Dr. Ronald C. Lasky
If asked what technology product defines today, one might first answer the personal computer (PC). Although, 10 or 15 years ago that might have been the right answer, a little more thought will show that the mobile phone is today's technologically defining product. Sheer numbers tell the story: over 1 billion mobile phones are manufactured each year. Considering that the population of the world is about 6.5 billion souls, 1 billion mobile phones each year is an astounding number. In addition, a mobile phone is likely the most multi-functional personal device in existence. Just think, it can be a phone, camera, personal data assistant, web surfer, email device, text messenger, GPS device, portable music player, portable video player, streaming audio and video player, miniature PC, and probably a few more things. To package and assemble all of this electronic functionality in such a small device is a challenge indeed. This paper will discuss some of the assembly challenges of such miniaturized electronics.
lead-free, graping, stencil printing, solder paste
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Posted on 4 Mar 2010
by Aniket A. Bhave, Daryl Santos PhD, Dr. Ronald C. Lasky
Numerous studies have shown that greater than 60% of end of line defects in SMT assembly can be traced to
solder paste and the printing process. Reflowing adds another 15% or so. In light of this fact, it is surprising that no simplified procedure for solder paste evaluation has been documented. This paper is about such a procedure.
pb-free, lead-free, stencil printing, solder paste, solder paste evaluation
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Posted on 31 Mar 2010
by 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 active and passive electrical components. Not too long ago, 0401 (40 x 10 mils) passives were seen as the ultimate in miniaturization, yet the introduction of 0201s and, most recently, 01005 passives have occurred. For active components, area array packages with 0.4mm lead spacing have become virtually a requirement for enabling the many features in modern portable electronic devices, with 0.3mm packages already on the way.
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 the specific challenge of the graping effect and the work that has been performed to mitigate this phenomenon. Discussed are the effects of the solder paste material attributes, consistent stencil printing of the small solder paste deposits required, and minimizing oxidation of the small solder paste deposit during reflow. All of these steps are necessary to assure a good finished solder joint.
solder paste, graping, oxidation, stencil printing
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Posted on 21 Jan 2011
by Wang Ming, Aniket A. Bhave, Dr. Daryl Santos, Dr. Ronald C. Lasky , Sniket A. Bhave
Numerous studies have shown that greater than 60% of end of line defects in SMT assembly can be traced to
solder paste and the printing process. Reflowing adds another 15% or so. In light of this fact, it is surprising that no simplified procedure for solder paste evaluation has been documented. This paper is about such a procedure.
By using designed experiments and the measurement of critical solder paste related process metrics, we were able to develop a solder paste evaluation procedure that maximizes information about the solder paste and its processability while minimizing experimentation. While using only 12 stencil printed PWBs, we were able to generate statistically significant results that enabled us to rank solder pastes according to their performance. Response metrics that were investigated were print volume and definition before and after pause, squeegee hang up, slump, tack, release from aperture, and solder joint quality.
In addition, we found such variation in solder paste volume repeatability that this criterion alone can be used as a screening procedure.
lead-free, pb-free, solder paste evaluation, solder paste, stencil printing
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Posted on 9 Mar 2010
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
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Posted on 1 Jan 2009
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 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
