-
- News
- Books
Featured Books
- smt007 Magazine
Latest Issues
Current IssueBox Build
One trend is to add box build and final assembly to your product offering. In this issue, we explore the opportunities and risks of adding system assembly to your service portfolio.
IPC APEX EXPO 2024 Pre-show
This month’s issue devotes its pages to a comprehensive preview of the IPC APEX EXPO 2024 event. Whether your role is technical or business, if you're new-to-the-industry or seasoned veteran, you'll find value throughout this program.
Boost Your Sales
Every part of your business can be evaluated as a process, including your sales funnel. Optimizing your selling process requires a coordinated effort between marketing and sales. In this issue, industry experts in marketing and sales offer their best advice on how to boost your sales efforts.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - smt007 Magazine
A Review of the Opportunities and Processes for Printed Electronics (Part 3): Materials, Process Developments
June 24, 2015 | Happy Holden, PCB Technologist-RetiredEstimated reading time: 10 minutes
Table 3: Applications and substrates
Flexible materials are a key characteristic of PE. Many products traditionally utilize glass to protect the active layers. To replace glass, the flexible substrates need to be an effective barrier against oxygen and water vapor, be sufficiently strong not to rip or tear and, if a cover, transparent to visible light. Many plastics, such as such as Mylar, polyimide, PET and ORMOCER, have these characteristics. Substrates can even be papers and paper hybrids. Applications and substrates are summarized in Table 3.
The majority of the world's PET production is for synthetic fibers (in excess of 60%) with bottle production accounting for around 30% of global demand. In discussing textile applications, PET is generally referred to as simply polyester while PET is used most often to refer to packaging applications. The polyester industry makes up about 18% of world polymer production, followed by PE and polypropylene (PP).
PET consists of polymerized units of the monomer ethylene terephthalate, with repeating C10H8O4 units. PET is commonly recycled, and has the number 1 as its recycling symbol. PEN is a polyester with good barrier properties (even better than PET). Because it provides a good oxygen barrier, it is well-suited for bottling beverages, such as beer, that are susceptible to oxidation. It is also used in making high performance sailcloth. PPG’s Teslin is a polyolefin matrix with high silica filler.
Table 4: Characteristics of Substrates
DuPont’s Teijin Films are polyester films that are pre-treated on both surfaces to promote adhesion to most industrial coatings. Melinex, Mylar, Cronar and Teonex are registered trademarks of DuPont Teijin Films. Teslin and Teijin Films are designed for PE application like RFID, batteries, OLEDs and sensors.
PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained at high temperatures. The Young's modulus is 3.6 GPa and its tensile strength is 90 to 100 MPa. PEEK has a glass transition temperature of around 143°C and melts at around 343°C (662°F). It is highly resistant to thermal degradation and attack by both organic and aqueous environments. At high temperatures, it is attacked by halogens and strong Bronsted and Lewis acids, as well as some halogenated compounds and aromatic hydrocarbons.
If it is very thin, glass can also be a flexible substrate. AGC and Corning have both developed ultra-thin glass (only 0.1mm thick) for OLEDs and other applications. Alkali-free glass is composed of silicon dioxide, boron oxide and aluminum oxide and is free of sodium and potassium, so it is used widely as a substrate for thin-film transistor liquid crystal display (TFT LCD) and OLED. Soda-lime glass is composed of silicon dioxide, sodium oxide and calcium oxide and is widely used in construction, automotives and many electronics devices.
Recently, a research group at the Hebrew University of Jerusalem has developed a nanotechnology ink that self-sinters at room temperature. The researchers have demonstrated that the new silver nanoparticle-based ink can be deposited and provides post-print conductive properties without a post-sintering process step. Instead, the properties of the nanomaterial are used to make the ink aggregate and self-sinter. The elimination of the temperature needs associated with normal sintering processes opens the door to processing cost reduction and the use of lower cost, temperature-limited substrates, including paper and lower melt-temperature plastics (Table 4).
Other companies are developing catalytic inks that can be electrolessly or electrolytically plated to achieve the necessary conductivity. One company of note—Conductive Inkjet Technology—has been developing a range of equipment for printing catalytic circuit patterns on material webs in a roll-to-roll fashion. When the catalytic ink is electrolessly plated, the company reports that the conductivity ranges from 50mΩ to 20mΩ per square. The company’s technology, which has an approach that is similar to a technology developed in Silicon Valley around 1990, can reliably produce typical feature sizes down to less than 250μm, which is finer than earlier technology that used a laser printer and catalytic toner. While some have performed its initial process and equipment development on an inkjet platform, the company's literature indicates that they can produce 50μm features using flexographic printing, which could prove to be an important departure.
Flexographic printing, as a follow-on technology in the same market space, opens the door to higher production rates and offers the potential to print both sides of a two-metal layer circuit in a single pass. With some creativity, it is possible that inkjet printing could be similarly adapted. One concern about this technology is that it will produce circuits that will build both vertically and laterally, reducing the space between circuits and potentially causing shorts.
Post plate-up technology shares many of the same concerns as laser printing technology in terms of managing feature dimensions in process. Metrics are usually predicated on three items:
- Resolution, or how many dots per unit length
- Drop size, or how small each dot is
- Print rate, or dots per second
Page 2 of 3
Suggested Items
Electronics Industry Sentiment Rose in April, Hitting New High
05/02/2024 | IPCApril 2024 marked the third consecutive month of sentiment growth among electronics manufacturers. When asked if they expected labor costs for hourly workers to rise over the next month, manufacturers in the United States, Mexico, and Europe predicted a five percent increase, while manufacturers in Asia predicted a slightly lower four percent increase.
iNEMI Names Grace O'Malley CTO
05/02/2024 | iNEMIThe Board of Directors of the International Electronics Manufacturing Initiative (iNEMI) has named Grace O'Malley Chief Technical Officer (CTO).
ZESTRON Academy Launches 2024 Advanced Packaging & Power Electronics Webinar Series
05/01/2024 | ZESTRONZESTRON, the leading global provider of high-precision cleaning products, services, and training solutions in the electronics manufacturing and semiconductor industries, proudly announces the launch of its highly anticipated webinar series on Advanced Packaging & Power Electronics, a webinar series on the latest innovations, cleaning, and corrosion challenges.
NextFlex Convenes the Hybrid Electronics Community at Binghamton University
05/01/2024 | NextFlexBinghamton University hosted the NextFlex hybrid electronics community on April 18 for a day of expert presentations, breakout sessions on technology and manufacturing topics, and networking.
HQ NextPCB of HQ Electronics Debut on the International Stage for Electronics Manufacture at IPC APEX 2024
05/01/2024 | PRNewswireHQ NextPCB of HQ Electronics, a leading Chinese-based multilayer PCB manufacturer and assembly house showcased its industrial prowess on the international stage for the first time at the IPC APEX Expo 2024.