2015, ATLANTA - SGIA PRINTED ELECTRONICS SYMPOSIUM November 3rd 4th

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1 2015, ATLANTA - SGIA PRINTED ELECTRONICS SYMPOSIUM November 3rd 4th The Sperior Screenprinting Performance with Ultra-Hard Stainless Mesh -Strikingly Improved Dimension Accuracy- Advanced Screen Printing Meshes and the Future Roadmap for Screen Printed Electronics Fernando Zicarelli 30 micron Hand Print

2 Company Overview Asada Mesh Co., Ltd Founded in: 1940 Employees: 258 (as of May 1, 2015) Osaka Headquarters Scope of Business: Manufacturing of woven wire mesh for Screen printing for Filtering, sieving etc Kagoshima Plant, Japan Suzhou Plant, China Handloom

3 Contents: Open Innovation Hub Stainless Mesh & Screen Printing What does the Industry want? Advanced Screen Printing 101 Ultra-Hard HS-D-mesh The Latest Screen Printed Electronics

4 Open Innovation Hub OIH was built with the idea of helping PE Companies and Development Centers throughout the World to have access to our finest metal mesh Screen Technology. We will contribute by bringing people together to create new Screen Printing Technologies Asada Mesh Co., LTD. R&D Center Technical Screen Printing support from: Screen Selection Screen-Making Screen Printing Optimization Analysis Up to 1000mm Size Screens 4 Printing Machines Asada Mesh New R&D Center

5 Reed Manufacturing Process of Screen Mesh wires are needed for 500/ Wire Receiving Inspection 2. Warp Beaming 3. Heddles & Reed Threading Surface Quality Mechanical Property Black Screen Calender Machine 4. Adjustment & Weaving 5. Value-Added Process 6. Quality Inspection

6 Process of Screen Mesh Making Calender Machine 1. Wire Receiving Inspection 2. Warp Beaming Precise Resolution Exposure 3. Heddles & Reed Threading Surface Quality Mechanical Property Black Screen Calender Machine 4. Adjustment & Weaving 5. Value-Added Process 6. Quality Inspection

7 Asada Mesh s Roadmap for Printed Electronics: Unfortunately, the higher the mesh count is, the smaller the strength index will be HS- D mesh has been developed with Higher Tensile Strength: 7

8 Why is Mesh Strength so important? A Polyurethane Squeegee pushes a Screen Mesh an moves an Ink across the openings on the Emulsion. The emulsion openings define the pafern. The Gap between the screen mesh and the substrate is called Snap- off and it is one of the most important variables that affects the quality of the printed pafern. When the Screen Mesh is stretched repeatedly, the Image begins to deform. That s the reason why the Mesh Strength is very important for High Quality Screen PrinNng. 8

9 Understanding Index Strength: BS- 325/28 ( 325mesh with 28 micron wires ) is regarded as a stainless steel wire mesh that has been used in Mass ProducNon for years. We have set BS- 325/28 strength as a benchmark to compare a Screen Mesh Strength easily. "Strength Index of screen mesh can be found out only from three factors - wire strength, cross- secnon of wires and mesh count. Example: MS- 400/23 ( 400 mesh with 23 micron wires ) can be calculated as shown below: 9

10 WHAT DOES THE INDUSTRY WANT? 10

11 MLCC Request from MLCC industry: Thickness must be thinner and thinner!!! Industrial demand for thinner inner electrode has increased due to size and capacity. Higher mesh counts over 400 are widely used for MLCC manufacturing process. Up to 500 MLCCs of size 0603 (.6mm x.3mm) and 0402 (.4mm x.2mm) can be integrated into a single smartphone. hfp:// = L0.4mm x W0.2mm Print Make Layers Press Complete Stainless Steel Wire Mesh Wire Dia.*Mesh Count Thickness (µm) Chip Size Ink Volume (µm).0009"* "* & "* "* Industrial Partners: Murata, TAIYO YUDEN, TDK, Kyocera and Samsung Electro- Mechanics have tested 730 and some of them are using it already. 640 has been used in Mass Produceon. 11

12 MLCI Request from MLCI & Chip- R Industry: Fine Line with High Aspect RaNo!!! Chip Inductor; Chip Inductors are Passive Electronic Devices which can save electric energy in magnenc form. Electrodes are Screen Printed on Dielectric Ceramic Sheets forming a coil. The required line width is usually microns with high aspect rano. Dimensional accuracy is also important because Via- Holes must align to each other. High Open rano mesh is mainly used in this applicanon. Substrate = Glass Ceramic Green Sheet Ink = Silver Paste ( High Viscosity ) Substrate = Alumina Ceramic Ink = Silver Paste & ResisNve paste Chip Resistor; A rectangular electrode and resisnve paste are printed on an alumina ceramic substrate. Chip sizes are gejng smaller; down to Higher printed resolunon and dimensional accuracy are needed. The process of the "Trimming" which modifies a resistance value is adopted convennonally, "Trimming" may become unnecessary if prinnng quality improves. 12

13 Touch Panel Silver Traces of Touch Panel: Screen PrinNng has been used to produce Silver Traces for Touch Panel because it is the most economical and producnve method. Screen PrinNng technology has been improving to meet the requirement of high funcnonality and slim borders on smartphones. Capacieve Two Layer Construceon Top PET with ITO and Silver Traces OCA (OpNcal Clear Adhesive) BoFom PET with ITO and Silver Traces Screen Mesh and Paste Rheology must be opnmized to implement High Quality Screen PrinNng. 13

14 PE & MEMs Printed Electronics & MEMs AlternaNve deposinon methods are currently used like photolithography, spraying and ink jejng ; however Screen PrinNng is a robust manufacturing technology which has been used for many years. Screen PrinNng is an addinve process and very cost effecnve even when the substrate size is larger. Asada Mesh believes that our new generanon of meshes HS- D will be able to mass produce Printed Electronics components for many applicanons including MEMs, Sensors, BaFeries, etc. Flexible Current Clamp Sensor Using Screen- Printed Coil A novel flexible current clamp sensor with 480 turns obtained using a Screen PrinNng Ag paste Line / Space = 50μm / 70μm (connecnons are formed via filled Through- holes) Industrial Technology Development OrganizaNon (NEDO) projects 14

15 Screen-Printing " A Standard " that Asada mesh recommends Mesh Screen Print Determined by Strength Opening Ratio Thickness Mesh Count Training program of learning Stretching Method Appropriate Tension Trampoline (Poly + SUS) Emulsion Coating(Flatness) Understanding of Squeegee & Scraper Type 4 Printing Conditions

16 Stainless Mesh & Screen Printing Advantage of High Mesh Count Screens OIH Experiment: Compare 325/28 vs 500/19 Screens A Standard Recommends High Mesh Count Screen is necessary to achieve high resolution fine lines 325mesh ( micron) 500mesh ( micron) Printable Line Width is from 0.8 to 2.0 of Mesh Pitch 50 micron Frame : 450mm Substrate : Si Trampoline SQ :200mm/sec

17 Photovoltaic Screen Mesh with 40% Opening Area: High Open Area mesh can cause Paste Bleeding because of the mismatch between screen mesh opening area and the paste. The surface of the printed electrode with 60% of opening area is very rough compared with to a 40% of opening area mesh. Paste A 40% 40% 50% 50% 60% Figure 1. Finger electrode designed 50μm width using mesh screen with 39% opening rate (leu), 49% (middle) and 60% (right) for paste A.

18 Contents: Open Innovation Hub 2. Stainless Mesh & Screen Printing 3. Ultra-Hard HS-D-mesh 4. The Latest Screen Printed Electronics

19 From past to present micron 50 micron 19 micron 28 micron 15 micron 13 micron Human hair and micro wire Stainless Mesh technology advanced rapidly in the last 50 years. We are now introducing 900 which is 5 times finer mesh count than 165 developed in However; there is only one technical challenge for high meshes to overcome. 80µm 12µm

20 Mesh Strength Thinner wires must be selected to weave high meshes. The higher mesh count is, the smaller the strength index will be. Strength Index is a reference value setting BS325/28 to standard 1.0. Wire diameter has a significant impact on Mesh Strength. Wire Strength Cross Section Mesh Count 28 micron 13 micron S=πr2

21 Wire Hardness and Opening Rate Type of Material Wires 1.0 From 200 to 500mesh Opening Rate : 40% 1.3 From 250 to 730mesh Opening Rate : 40% From 230 to 380mesh Opening Rate : 60% 3.0

22 Special Structure of HS-D Mesh , 500 and 650 mesh Opening Rate : 40% 3.0 threads are woven over and under two warp Plain Weave Twilled Weave

23 2 Different Experiments with HS-D Mesh Strength and Strain of Wires Comparison of Screen Distortion Dimensional Accuracy Test 300 prints HS-D Screen vs. Conventional Frame : 550mm Pattern : 200mm Snap Off : 3.8mm Experiment of HS-D Screen Distortion Dimensional Accuracy Test prints ±10 micron Variation between 2 axes is within ±10 µ

24 Changing the Industry Standard Advantages of Ultra Hard HS-D Meshes Advantages of HS-D Mesh High Dimensional Accuracy Yield Point is extremely high so that it achieves high dimensional accuracy. Makes it possible to produce Multi-Layered PE devices. High Resolution Super High Viscosity Paste can be used with high Snap- Off distance. Fine and high-density mixed patterns can be printed on a Low absorption PET film. Fine Fingers High Mesh Count 500 and 650 mesh have been developed to print less than 30 microns. Longevity A High Strength HSD Screen achieves longer Screen life. High Density Pattern 30 micron on PET

25 Contents: Open Innovation Hub 2. Stainless Mesh & Screen Printing 3. Ultra-Hard HS-D-mesh 4. The Latest Screen Printed Electronics

26 Conductive fingers for SWT/HIT Solar Cells (6 month development work): Based on a comparison, narrower fingers can be screen printed (figure on right) Applied on solar cells, an increase up to ~1% rel on cell efficiency was reached < 35um wide fingers are uniformily printed on textured solar cell surface Finger heights are more uniform with less peaks and valleys Finger width and resistance function of mesh count used Influence of pastes & meshes used regarding cell performances Confocal image of screen printed fingers with MS730

27 Screen Printed Electronics for real-time monitoring and control of the power system Flexible MEMS Fabricating a Low Cost Flexible Thin Film Current Sensor This flexible current sensor with 369 turns silver paste coil (L/ S=50/70 micron) is produced by Screen Printing. Ultra Hard HS-D mesh achieved a silver coil circuit printed on the front and back with high dimensional accuracy. 50 micron Via Filled Stencil Printed Screen Print 60 micron Smart grid is the latest trend in the global power system. It is important to develop a mass production technology of small size and inexpensive sensors. This research has been conducted with the support of the National Institute of Advanced Industrial Science and Technology.

28 Example of Screen Printed Transistor University of Tokyo Someya Group mm Organic Transistors Printed Electronics 2.5mm pitch 2T1C Large Organic Transistor Array A 2.5mm pitch, 2T1C Large Organic Transistor Array is produced only by Screen Printing on PEN film. Gate and S/D electrodes of 30 micron channel length are printed with HS-D650 mesh and a High Viscosity Paste. 6 screens were used to achieve an accurate alignment on a multi-layered structure. 1.via-fill 2. back side electrode 3. gate electrode 4. gate insulator 5. S/D electrode 6. Passivation mask Example: TFT back plane for organic Electro Luminescence Display or E-paper 30 micron S/D electrode Various Flexible Sensors Via-Fill Support of The University of Tokyo Someya Group

29 Low Melting Solder Paste for ML-PCB: Ag coated Cu paste with low melting temperature of 160 degrees makes SMT possible on PET film A Single-Sided / Multi-Layer Substrate Multi-Layer Printed Circuit Board Screen Printing relies on a unique principle of depositing paste in a screen mask openings onto a substrate with a rubber squeegee and excels in printing on a rugged substrate. Since PE devices require multi-layers, Screen Printing is ideal for PE manufacturing process. Typical Design Printed on Rough Substrate Surface Mount Device Screen Printing instead of Stencil realizes consistent paste deposition +/- 20%. Low temp solder paste (160 degree) allows mounting components on PET film. Achieves multi-layered Structure Low melting Small particle Solder Paste Reduces Manhattan Phenomenon Frame : 550mm Mesh : HS-D360/25/CL41or 59 Line Width : 200 micron Paste : Tatsuta Electric Wire & Cable

30 High Viscosity Paste for Decorative Screen Printing Printed on substrates with low water absorption such as PET or glass (Some Cell Phone manufactures are interested in it for decorating backside of a cell phones) High Definition Decorative Screen Printing Achieved with a new designed Concept Paste Conventional paste causes bleeding easily(left). Low viscosity paste, which has been used for decorative printing for years, cannot be used for high definition printing because it causes bleeding easily. High quality and high definition printing can be achieved in combination with a high viscosity paste and HS-D mesh, solving the problems of bleeding and delayed peel off issues. GRADATION PATTERN on a PET film 80ppi 25 micron Gap 100 Pa S - 30 times higher viscosity paste than conventional paste has helped reduce the bleeding level to less than 8 micron with a higher snap- off distance. Frame : 550mm Mesh : HS-D500/19/CL25 Paste : Teikoku Printing Inks Mfg.Co.,Ltd.

31 HS- D Cl- 25 for Touch Panel MS-500 Cl = 25µ Roll to Roll 300 sheets prints, EOM15µm, Screen Size 880X880mm Squeegee Angle 40 degree Squeegee Speed 40mm/sec 50μm L/S Mesh Count 500 Wire Diameter 19 micron Opening 32 micron Opening ratio 39 Thickness 25 micron CL 50μm L/S Silver Traces in Touch Panel in Japan are now 60 micron pitch L/S=30/30 using Most of Touch panel manufacturers in China started adopting Laser trimming or Photo Sensitive Paste. Circuit patterns have been made with Photolithography. 31

32 MS- 500/18 Cl=25µ Mesh Count: 500 Wire Diameter: 18 µm Opening: 33 micron Opening ratio: 42 % Thickness: 25 µm 30 µm line width with 70 µm spacing Etching resist (Kansai Paint) 32

33 MS- 640/15 Cl=18µ MS-640/15 Cl=18µ Mesh Count : 640 Wire Diameter : 15 micron Opening : 25 micron Opening ratio : 39% Thickness : 18 micron CL 30μm 20μm 25μm Paste ML-4019 for LTCC; Emulsion Thickness = 20 µm; Theoretical Ink Deposit 6.96 cm3/m2 33

34 MS- 840/11 Cl=11µ (replaced by 900/12): 16μm/ 24μm L/S MS-840/11 Cl=11µ Mesh Count : 840 Wire Diameter : 11 micron Opening : 19 micron Opening ratio : 40% Thickness : 11 micron CL Flexible Printed Circuit Application, Frame Size:320mm x 320mm, EOM 5 micron, Ag paste 34

35 75 YEARS OF CONSTANT INNOVATION THANK YOU FOR YOUR ATTENTION fernando- mesh.co.jp 35