PCB Encapsulation - The Best Way to Protect Electronic Circuits PCBs are used in
numerous industrial, domestic, automotive and military devices, often in extreme
environments. Exposure to moisture, harsh chemicals and other harsh conditions
can damage PCBs, resulting in a reduction in electrical performance of PCBs or
complete failure of the device. PCB encapsulation with resins ensures that the
circuits are well protected. These resins offer the highest level of protection.
Encapsulation of the entire PCB with resin allows for complete insulation,
thereby giving the unit excellent electrical properties and mechanical
protection. The extent of encapsulation varies according to the application and
plastic activation.
Mechanical protection includes superior protection
for applications that are exposed to vibrations PCB Prototype, and thermal or physical
shock. PCB encapsulation involves the use of a dispensing machine with resins
commonly two parts which when mixed together under controlled temperature and
pressure form a solid, fully cured protective material. The entire unit is
tested thoroughly for its intended use in an appropriate environment. This could
be planned accelerated testing. The resins can also be tested independently in
different environments to determine the precise specifications and suitability.
The dimensions and weight of the resins are measured before and after the test
to record any changes, if any. Other tests include electrical testing, which is
specific to the final application Rigid
flex.
PCB encapsulation is a cost effective and accurate process
that ensures that PCB assemblies operate safely in various conditions.
Encapsulants are available in solid and liquid form although their composition
is similar. Epoxy molding compounds are solid types that are a blend of solid
epoxy resin, additives, flame retardant, and hardener. On the other hand, liquid
encapsulants have liquid resin and hardener so that the material can be applied
directly on the chip and interconnect using the dispensing machine. Most
encapsulants use epoxies that react with hardeners such as anhydrides. One of
the major reasons for using epoxies is because of their versatility and balanced
characteristics. The additives bring the properties to the desired level to act
as encapsulants. Flame retardants are added to the process to meet the required
specifications and reduce flammability.
Solid and liquid epoxies are
polymerized. The compounds are low melting mixtures of resins and other material
that is polymerized into a structure with good mechanical strength and thermal
stability to ensure there is no damage in the soldering assembly process. In
liquid encapsulants, polymerization occurs when heat is applied to the unit that
contains epoxy resin, hardener, and an accelerator. One of the common processes
of encapsulation is transfer molding. Connected chip are fed into a mold cavity
of a molding machine. The epoxy molding compound is preheated and melted into a
liquid and injected into the mold cavity to surround the chip and wire bond
structure.
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