As seen in the August issue of PCB007 Magazine: http://iconnect007.uberflip.com/i/1011746-pcb007-aug2018/78
“The science of today is the technology of tomorrow.” This Edward Teller quote is an
apt description of the Mina product. This advanced surface treatment, recently developed to enable low-temperature soldering to aluminum in the RFID market, is not only finding success in that market, but quickly finding a home in other markets, including the LED market, where the incentive is both cost and improved LED performance. I recently had the opportunity to speak with Divyakant Kadiwala, from Averatek, to discuss the development of Mina and potential applications for this surface treatment. The science behind the ability to solder to aluminum can be summarized as the battle against aluminum oxide. Removing the oxide is easy but keeping it from reforming is extremely hard in ambient conditions. Development was focused on coming up with a surface treatment that removes this oxide at the correct temperature—the temperature at which solder reflows. This would ensure the formation of a strong bond between the bare aluminum and molten solder as it cools down. This advanced surface treatment is enabling technology across more than one market.
RFID Tag Market
This surface treatment was originally designed for the high-volume RFID tag market.
For cost reasons, aluminum-polyester (Al-PET) materials are a preferred choice, but this material does present some challenges. Aluminum is difficult to solder to at lower temperatures and PET cannot withstand high temperatures. Soldering to aluminum is difficult because of the presence of a thin layer of aluminum oxide that is present when Al-PET is exposed to air. The oxide can be removed with extensive wet chemistry but adds cost and makes this material cost prohibitive in high volume. Anisotropic conductive paste (ACP) is a common solution to this challenge and is widely used for attaching components to aluminum-based RFIDs. It is applied to the face of the chip, which is attached to the antenna using heat and pressure. However, ACP has its own challenges. It is typically syringe applied, requires longer cure times, has pot-life issues and is electrically inferior to conventional solders. In addition, it must be stored at low temperatures in special freezers to control the polymerization of the epoxy.
As Mina is entering the market and people are learning more about it, discussions of applications in other industries are happening and other potential uses are being explored. One prominent market also poised to benefit from Mina is the rapidly growing LED market. According to a study from Zion Market Research, the LED market is predicted to have a 13% CAGR from 2107 to 2022, with an estimated market of $54 billion in 2022. In the LED market, Mina can both lower cost and improve performance. The underlying goal for better performance in the LED market is keeping the LED cooler. One segment of the LED market, using thinner aluminum and less expensive materials, has similarity to the RFID tag market. Currently, base materials vary between copper-PET laminate and aluminum-PET laminate. Applications using Al-PET materials also typically bond to aluminum using the conductive epoxy method mentioned earlier. The use of Mina in these applications results in a true metal-to-metal bond that improves both the electrical performance and the thermal conductivity. As a result, the LED stays cooler.
Oftentimes in this segment of the market, copper-PET materials are being used when the
conductive epoxy approach to assembly does not provide the needed performance. Mina
would enable the adoption of the Al-PET materials which can reduce the cost of the base
materials by 80%. Once Mina is applied, the traditional soldering process used on copperPET circuits can be performed. In the high-power LED segment of the market, thicker copper with a polymer dielectric is most commonly used. This dielectric does provide some thermal performance. The introduction of Mina has provided another option for consideration and improved performance of LEDs. LED systems typically consist of a package, board and heat-sink. The package consists of the LEDs with
two leads, and a separate thermal pad in case of high power LED systems. The traditional board can be eliminated by the combination of Mina and Averatek’s ALD additive circuitry process. Alumina, the anodized layer of aluminum, is a thermally conductive, electrically insulated dielectric layer. From a 10,000-foot view, Averatek’s ALD ink additive circuitry process generates the copper traces directly on the alumina or dielectric layer. Mina can be used to solder both leads that need to be electrically grounded and the thermal pads, directly to the aluminum. This can be done by
masking the bonding areas when anodizing the aluminum prior to building the copper traces and then applying Mina to those previously masked areas allowing soldering to the aluminum. This provides better thermal management and significantly improves performance. Mina has been developed to work with standard screen printing, baking and assembly equipment. This allows a simple adoption without incurring significant capital equipment costs. As a new with benefits to two markets, I have to wonder which industry will be next to discover Mina. Hard disk drives? Connectors? Shielding wire and cable? Mina is an excellent example of innovation and technology development benefiting multiple segments in the rapidly changing electronics industry.