TRIZ Case Study:


Improvement of Material Properties of Printable Adhesive
Jae-Hoon Kim, Joon-mo Seo, Young-Ju Kang and Byoung-Un Kang (LS Cable, Ltd., Korea)
Presented at The Third TRIZ Symposium in Japan, Held at TOSHIBA Kenshu Center, Yokohama, on Aug. 30 - Sept. 1, 2007
[Posted on Jan. 29, 2008]  Under the permission by the Authors.   

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Editor's Note (Toru Nakagawa, Jan. 11, 2008)

The paper posted here was originally presented last August at The Third TRIZ Symposium in Japan held at TOSHIBA Kenshu Center, Yokohama.  For the overall view of the Symposium, please refer to my intensive 'Personal Report' .  The paper was presented in a poster session on the second day afternoon. 

This pesentation is nice and useful because the Authors applied TRIZ to a real industrial problem systematically and described clearly and closely how they applied the methods in the analysis and idea generation and what they obtained as the observations and solutions. Such a way of description is not only done by the present report but also by several other reports published recently by LS Cable and a few other companies in Korea. It is very valuable for many TRIZ learners and users to understand how to use TRIZ and how useful and effective it is. We are very grateful to the four coauthors of the paper and LS Cable, Ltd. for their contributing this presentation to the TRIZ Symposium and for thier kind permission of posting it at this Web site, TRIZ Home Page in Japan.

This paper was initially arranged to be presented at a single-track oral session, but was moved to a poster session according to the Presenter's request due to some scheduling uncertainty in the attendance. Actually, the Presenter (Mr. Jae-Hoon Kim) presented the paper in the poster session during his only several hours of stay in the Symposium. We thank him for his presentation.

 

Top of this page Abstract Nakagawa's introduction Full Paper in PDF (312 KB) Slides in PDF (657 KB)   Japan TRIZ Symposium 2007 (Nakagawa Personal Rept.) Japanese page

 


[1] Abstract

Improvement of Material Properties of Printable Adhesive

Jae-Hoon Kim*, Joon-mo Seo*, Young-Ju Kang** and Byoung-Un Kang*
*Electronic component R&D center, LS cable Ltd.
** Triz engineer, LS cable Ltd.

Abstract

In order to print uniform pastes on PCB without clogging, bubble and bleeding-out problems, TRIZ and other field of related studies were applied to simulate the issue and suggest solutions. That is, the defects were analyzed by tools like Root & Cause, Structural Analysis, Knowledge Search, Inventive Principle, Patent Search and Technical & Scientific Effect. Thereby, effective solutions were derived for the defects, which were verified through the practical data from several experiments. Finally we could get enhanced ways to reduce the defects (approximately 0%), followed by high yield % in mass productions.

Keywords: Paste, Screen printing, MRT, A/B/C-stage, TRIZ, Root & Cause, Structural Analysis, Knowledge Search, Inventive Principle, Patent Search and Technical & Scientific Effect, Chip-attach, Substrate, Semi-conductor, clogging, bleeding-out.

Extended Abstract

1. Problem list

Assumed factors that may cause the defects were analyzed in aspect of two categories – process and material :
1.1 Process factors can be what can affect material properties that may cause the defects, such as printing parameters – squeegee speed, separation speed, squeegee pressure, etc.
1.2 Material factors can be a material property itself that may cause the defects, such as surface tension, thixotropy, additives, etc.

2. Creative stage

The defect factors analyzed in the “Problem list” should be modified in some ways, so that an adjustment for each factor has been suggested in this section.

3. Evaluation list

Throughout the previous sections, each factor was evaluated in the basis of its impact for the defects.

4. Approach by TRIZ

The selected factors were focused to be modified and improved in order to solve the defect problems. Function and structural analysis was used to show the relationship between causes and results of the defects. Thereafter, the previous examples in TRIZ study were applied to explain the relationship suggesting some idea and solutions for the defects

 

[2] Introduction & Review of the Presentation (Toru Nakagawa (OGU), Nov. 14, 2007)

Excerpt from Nakagawa's 'Personal Report of Japan TRIZ Symposium 2007' (posted on Nov. 18, 2007). 

Jae-Hoon Kim, Joon-Mo Seo, Young-Ju Kang, Byoung-Un Kang (LS Cable, Korea) [19] gave a nice presentation in a Poster session with the title of "Improvement of Material Properties of Printable Adhesive".  The problem is related to the printing process of adhesives on the print circuit board (PCB).  The printing process is shown in the following slide, with the Steps 1 through 5.  Three types of defects resulted in the printing are shown at the right column (i.e. Step 5); they are called Clogging, Bleed-out, and Bubble, respectively from the top to the bottom.   

A good point in the present case study (and also several more published recently from this company, i.e. LS Cable, Korea) is its systematic way of analyzing the problem and its clear and detailed description of the findings.  Observation of the whole printing process has revealed a common cause for deriving the three types of defects, as shown in the above slide.   Namely, in Step 3 the paste is dragged up by the mask due to somewhat high viscosity.  The Author carried out systematic analyses of the problem from the Process view (with Structure analysis) and from the Material view (with Knowledge analysis and with Patent analysis). 

With these analyses and with the help of TRIZ knowledge bases, the Author has found the mechanism of the present problem as shown in the following figures.  The adhesive paste is viscous and is drug up with the edge of the mask when the mask is lifted.  The paste is not a simple liquid of polymers but contains small particles to make it into a thixotropic medium, which means no flowing when it is free but flowing when it receives shear stress.  Effects knowledge base in IMC's Goldfire Innovator explains that the shear stress destroys the micro-structure around the particles in the thixotropic medium to let it flow, and hence the smaller the particles the smaller shear stress is enough to let it flow.  On the basis of this knowledge, the Author made experiments of introducing smaller sized particles in the paste polymer, and achieved good results of solving the three types of defects.

 

 


[3]  Full Paper

Full Paper (in English)   (PDF, 312 KB, 9 pages)  Click Here. 

 


[4] Presentation Slides

Presentation Slides (in English)   (PDF, 657 KB, 17 slides, 2 slides/page)  Click Here. 

 

 


[5] Links to the Japanese Pages

Japanese page

Introduction Slides in Japanese   (PDF, 195 KB, 3 slides, 2 slides/page)

 

 

Top of this page Abstract Nakagawa's introduction Full Paper in PDF (312 KB) Slides in PDF (657 KB)   Japan TRIZ Symposium 2007 (Nakagawa Personal Rept.) Japanese page

 

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Last updated on Jan. 29, 2008.     Access point:  Editor: nakagawa@ogu.ac.jp