Rheologically Assisted Design of Conductive Adhesives for Stencil Printing on PCB

Driven by the need to deliver new, lead-free, eco-friendly solder pastes for soldering electronic components to Printed Circuit Boards (PCB), electrically conductive adhesives (ECAs) based on epoxy, carbon nanotubes (CNT), and exfoliated graphite (EG) were designed. The rheology of the adhesives prepared is paramount for the success of the deposition process, which is based on stencil printing. Thus, a rheological analysis of the process was first performed. Then, an experimental protocol was defined to assess the relevant viscoelastic characteristics of the adhesives for stencil printing application. Different composite formulations of epoxy/CNT/EG were produced. Their rheological characteristics were established following the designed protocol and benchmarked with a commercial solder paste. The thermal and electrical properties of the composite formulations were also characterized. As a result, a new, electrically conductive adhesive was delivered with potential to be an eco-friendly alternative to the solder paste currently used in stencil printing of PCB.

SANSKAR BHARTI RANGOLI : MEDIUM TO CONSERVE TRADITIONAL ART OF RANGOLI FROM EXTRINSIC TO INTRINSIC

भारतीय संस्कृति एवं कला का अटूट संबंध है जहां संस्कृति की बात आती है वहीं भारतीय कला का रूपांकन नेत्रों में आ जाता है। भारतीय कलाओं में से एक है रंगोली कला। यह भारतीय पारंपरिक फ्लोर आर्ट है जिसे मुख्य द्वार के सामने तथा आँगन में किसी विषेष अवसर अथवा उत्सव व त्यौहारों पर बनाई जाती है, रंगोली न केवल आंगन की सजावट थी अपितु यह ईष्वर के आषीर्वाद प्राप्त करने के लिए, सौभाग्य के लिए एवं अतिथियों के सत्कार के लिए बनाई जाती है। रंगोली के कई प्रकार हैं, उसमें से एक है संस्कार भारती रंगोली जो महाराष्ट्र में अत्यधिक लोकप्रिय है। इसमें कई हिन्दू मान्यता एवं संस्कृति से संबंधित चिन्हों का प्रयोग किया जाता है। संस्कार भारती रंगोली में उपयुक्त होने वाली डिज़ाइनों का होम फर्निषिंग टेक्सटाइल उत्पाद पर विभिन्न वस्त्र अलंकरण जैसे- फैब्रिक प्रिटिंग (ब्लॉक, स्क्रीन प्रिटिंग, स्टेन्षील प्रिटिंग), फैब्रिक प्रिटिंग, एम्ब्रायडरी का उपयोग करना जिससे फैषन उपभोक्ता के लिए अद्वितीय डिज़ाइन बनाने अथवा पारंपरिक कला में उपयुक्त रंग, डिज़ाइन अथवा शैली का उपयोग कर रंगोली कला की डिज़ाइनों को संरक्षित करना है। संस्कार भारती रंगोली में उपयुक्त होने वाली आकृति को वर्ग, डिज़ाइन, समूह डिज़ाइन, के लिए अनुकूलित किया गया था।लेख के लिए कुल दस डिज़ाइन चयनित कर विकसित किए गए थे और फैब्रिक पेंटिंग के द्वारा होमफर्निषिंग टेक्सटाइल पर बनाने के लिए सर्वश्रेष्ठ 05 डिज़ाइन का चयन किया गया। उपभोक्ता के द्वारा भारतीय रंगोली कला संस्कार भारती रंगाली कला का उपयोग कर बनाए गए उत्पाद बहुत सराहे गए। संस्कार भारती रंगोली कला वस्त्रोत्पाद पर प्रयोग करके लेख तैयार किया गया है। Indian culture and Art Share an unwavering Connection between them. Indian art providespicturesque Slide view of Indian culture, Rangoli Art is one of the most prominent art amongIndian Art forms. This is a floor art, which were basically designed and embossed at mainentrance and courtyards. On various auspicious occasions and festivals Rangoli was designed togrant divine blessings of God as well as signifies the prosperity and heartwarming welcome ofguests. There are many varites of Rangoli in IndiaSanskar Bharti Rangoli is one of the most popular rangoli art of Maharashtra. This art formcomprises of many Hindu aesthetics, artifacts and cultural symbols. These symbols bring adistinct feature to Sanskar Bharti Rangoli. This paper aims at conservation of Rangoli art formby shifting its inclination to fabric embossing. These art form can be consummate by fabricprinting (Block, screen printing, stencil printing), fabric printing and embroidery can be used byfashion enjoy to uplift the unique experience of traditional colors, designs and styles to conservethese rangoli art formsSanskar Bharti Rangoli is designed to facilitate compatibility of shape, area design and groupdesign which brings appropriateness to art form. Ten art designs developed for this paper, on thecounter part, five best fabrics painting finalized to paint on Home furnishing Textile. FashionUsers appreciated the products designed with traditional Indian Rangoli art , Sanskar BhartiRangoli. This paper elaborates the efforts and significance of Sanskar Textile fabric,

Washable, Low-Temperature Cured Joints for Textile-Based Electronics

Low-temperature die-attaching pastes for wearable electronics are the key components to realize any type of device where components are additively manufactured by pick and place techniques. In this paper, the authors describe a simple method to realize stretchable, bendable, die-attaching pastes based on silver flakes to directly mount resistors and LEDs onto textiles. This paste can be directly applied onto contact pads placed on textiles by means of screen and stencil printing and post-processed at low temperatures to achieve the desired electrical and mechanical properties below 60 °C without sintering. Low curing temperatures lead to lower power consumption, which makes this paste ecological friendly.

Evaluation of The Printability of Lead Versus Lead Free Solder Pastes

As the global marketplaces consider mandating lead-free equipments, many questions arise about the impact and feasibility of replacing lead in printed circuit boards soldering applications. In this project, the results presented of a study on comparing the process of screening lead paste versus lead free paste parameters for regular stencil printing using standard manufacturing methods. The key process parameters studies were: squeegee speed, squeegee pressure, and screening yield for both types of pastes. Two solder paste formulations (lead paste and lead-free paste) were evaluated in this study. The analysis of the pastes deposit volumes showed that for normal manufacturing range of printer (screener) settings (speed and pressure) tested the two pastes performed the same. The results also showed that the squeegee speed has a greater effect on the printing process than the squeegee pressure. The tests clearly showed that the lead paste was affected more by setting changes compared to the lead free paste. Varying the print speed and pressure for type of pastes by observing the resulting printed paste volumes optimized screening parameters. This study confirms that a new stencil or stencil design is not needed for the lead free paste. However, this study recommends a change to the sitting of the screening print process. Stencil cleaning frequency is one of the main factors that impact the production rate in an SMT line. The project highlights new results that lead free paste throughput will be less compared to lead paste at the screening step. The number of rejected boards screened with lead free-paste exceeded normal manufacturing standards. As stencil cleaning is a must function, it was recommended to increase stencil wiping frequency when lead free paste [is] in use in order to obtain a consistent volume with less screening defect.

Evaluation of The Printability of Lead Versus Lead Free Solder Pastes

As the global marketplaces consider mandating lead-free equipments, many questions arise about the impact and feasibility of replacing lead in printed circuit boards soldering applications. In this project, the results presented of a study on comparing the process of screening lead paste versus lead free paste parameters for regular stencil printing using standard manufacturing methods. The key process parameters studies were: squeegee speed, squeegee pressure, and screening yield for both types of pastes. Two solder paste formulations (lead paste and lead-free paste) were evaluated in this study. The analysis of the pastes deposit volumes showed that for normal manufacturing range of printer (screener) settings (speed and pressure) tested the two pastes performed the same. The results also showed that the squeegee speed has a greater effect on the printing process than the squeegee pressure. The tests clearly showed that the lead paste was affected more by setting changes compared to the lead free paste. Varying the print speed and pressure for type of pastes by observing the resulting printed paste volumes optimized screening parameters. This study confirms that a new stencil or stencil design is not needed for the lead free paste. However, this study recommends a change to the sitting of the screening print process. Stencil cleaning frequency is one of the main factors that impact the production rate in an SMT line. The project highlights new results that lead free paste throughput will be less compared to lead paste at the screening step. The number of rejected boards screened with lead free-paste exceeded normal manufacturing standards. As stencil cleaning is a must function, it was recommended to increase stencil wiping frequency when lead free paste [is] in use in order to obtain a consistent volume with less screening defect.

Printed Textile-Based Ag2O–Zn Battery for Body Conformal Wearable Sensors

Wearable electronics are playing an important role in the health care industry. Wearable sensors are either directly attached to the body surface or embedded into worn garments. Textile-based batteries can help towards development of body conformal wearable sensors. In this letter, we demonstrate a 2D planar textile-based primary Ag2O–Zn battery fabricated using the stencil printing method. A synthetic polyester woven fabric is used as the textile substrate and polyethylene oxide material is used as the separator. The demonstrated battery achieves an areal capacity of 0.6 mAh/cm2 with an active electrode area of 0.5 cm × 1 cm.

Glue Voids Reduction on QFN Device through Material and Process Improvement

The paper is focused on the glue voids reduction on critical semiconductor quad-flat no-leads (QFN) device processed on a stencil printing type of die attach machine. Process optimization through material preparation improvement was done to mitigate the silver lumps of the sintering glue which is a main contributor on the voids occurrence. Eventually, the glue voids were reduced to less than the allowed 5% limit. For future works, the learnings and configuration could be used on devices with similar requirement.