IPC - HDBK-850
Guidelines for Design, Selection and Application of Potting Materials and Encapsulation Processes Used for Electronics Printed Circuit Board Assembly
|Publication Date:||1 July 2012|
For the purpose of this document potting can be thought of as the ''liquid material'' and encapsulation can be interpreted as the application process and cure. Please keep in mind however that the terms potting and encapsulation are commonly interchanged with each other in a variety of electronic protection processes.
Encapsulation, for the purpose of this document, is defined as a potting material, e.g., epoxy, silicone, urethane that is applied in a liquid state and subsequently processed (i.e., cured) to form a rigid or rubber-like state.
Processing characteristics and curing mechanisms are dependent on the encapsulation chemistries used. The desired performance characteristics of an encapsulation depend on the application and must be considered when selecting encapsulation materials and encapsulation processes. Users are urged to consult the suppliers for detailed technical data.
This guide enables a user to select an encapsulant based on industry experience and pertinent considerations. It is the responsibility of the user to determine the suitability, via appropriate testing, of the selected encapsulation and application method for a particular end use application.
Encapsulation may have several functions depending on the type of application. The most common are to:
• Inhibit current leakage and short circuit due to humidity and contamination from service environment.
• Inhibit corrosion.
• Improve fatigue life of solder joints to leadless packages.
• Inhibit arcing and corona, in particular for high voltage applications.
• Provide mechanical support and to prevent damages due to mechanical shock and vibration.
• Provide a mitigation method for the growth of tin-whiskers.
Purpose The terms ''potting'' and ''encapsulation'' (P/E) can be confusing terms and be interpreted to mean many things in various industry assembly processes.
The purpose of this handbook is to assist the individuals who must either make choices regarding encapsulation or who must work in encapsulation operations and to provide guidelines for the design, selection, and application of Potting and Encapsulation as it pertains to electronic components and printed board assembly only.