Rev 37 Operator’s Manual OM-610-1002-1
page 18 SECTION 5 OPERATION PDS-2010
5.3.2 Parylene Deposition
5.3.2.1 General
Parylene is formed (deposited) in place directly from a rarefied atmosphere of gaseous monomer. There is no
intermediate liquid phase and no "cure" cycle. The deposition and formation of Parylene on a substrate can be
viewed as a condensation process taking place in a room temperature vacuum chamber.
5.3.2.2 The Deposition Process
The Pary
lene polymers are deposited from the vapor phase by a process that resembles vacuum metallizing.
Unlike vacuum metalization, which is conducted at pressure of 1x10
-5
Torr or below, the Parylenes are formed
at around 1x10
-2
Torr. Unlike vacuum metallizing, Parylene deposition is not line-of-sight and all sides of an
object to be encapsulated are uniformly impinged by the gaseous monomer. This is responsible for the truly
conformal nature of the coating.
The deposition process consists of the following steps done in the presence of a medium vacuum:
1. Vaporization: Parylene is vaporized from its solid dimer form. This is accomplished by the application
of heat under vacuum.
NOTE: The appropriate term for passing directly from a solid to a gas is sublimation. However, the
industry has conventionally used the term vaporization in conjunction with the Parylene process. This
convention is maintained throughout this manual.
2. Pyrolysis (cleaving) of the gaseous form of the dimer into a monomer is achieved by using a high
temperature tube furnace.
3. Polymerization of the gaseous monomer occurs at room temperature as the Parylene deposits as a
polymer onto the substrate in the vacuum chamber.
5.3.2.3 Deposition Equipment
All Pary
lene deposition equipment must be able to accomplish these three steps. Figure 5-1 depicts the block
diagram of a typical Parylene deposition system consisting of the five main components, connected in series.
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