Impact of Non-Accelerated Aging on the Properties of Parylene C

Abstract

The polymer Parylene combines a variety of excellent properties and, hence, is an object of intensive research for packaging applications, such as the direct encapsulation of medical implants. Moreover, in the past years, an increasing interest for establishing new applications for Parylene is observed. These include the usage of Parylene as a flexible substrate, a dielectric, or a material for MEMS, e.g., a bonding adhesive. The increasing importance of Parylene raises questions regarding the long-term reliability and aging of Parylene as well as the impact of the aging on the Parylene properties. Within this paper, we present the first investigations on non-accelerated Parylene C aging for a period of about five years. Doing so, free-standing Parylene membranes were fabricated to investigate the barrier properties, the chemical stability, as well as the optical properties of Parylene in dependence on different post-treatments to the polymer. These properties were found to be excellent and with only a minor age-related impact. Additionally, the mechanical properties, i.e., the Young’s modulus and the hardness, were investigated via nano-indentation over the same period of time. For both mechanical properties only, minor changes were observed. The results prove that Parylene C is a highly reliable polymer for applications that needs a high long-term stability.

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“…Due to constructive and destructive interferences caused by the measurement setup in transmission mode, the obtained spectra featured a superposition with a sinus curve. In order to remove this sinus and smooth the spectra, the data were mathematically processed as described in 21 in detail. Briefly it can be summarized by fitting the sinus according to Eq.…”

Paradigm Changing Integration Technology for the Production of Flexible Electronics by Transferring Structures, Dies and Electrical Components from Rigid to Flexible Substrates

“…Considering the fact that the Parylene coating and sacrificial layer release are the last process steps in the presented technology flow, particularly, fabrication and integration processes with an increased thermal budget are avoided. Hence, the alteration of the Parylene properties is prevented as well [ 32 ].…”

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“…[2] However, other studies have revealed a dependency of the Young's modulus and the hardness on the thermal budget, which is assumed to be caused by recrystallization of the partially crystalline polymer. [5] Hence, free-standing Parylene C membranes of 5 µm thickness were fabricated according to the process and using the equipement given in the literature [2] and stored under the typical conditions of a bonding process, i.e. 30 min in vacuum at 260 °C, 280 °C, 300 °C, and 320 °C, respectively.…”