“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.
Figure 1: LED performance improvement per 10°C drop in temperature. (Source: Averatek)
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.
To read the full version of this article which originally appeared in the August 2018 issue of PCB007 Magazine, click here.