WACKER launches high thermal conductivity silicone potting compound for on-board chargers

OBC (on-board charger), as one of the key components in new energy electric vehicles, converts alternating current into direct current required by the electric vehicle power battery, ensuring that the battery can be fully charged safely and automatically, which determines the charging of electric vehicles efficiency
.
At present, the design of OBC has been integrated including bidirectional power conversion, DC-DC conversion and other auxiliary device functions.
The integration gives the OBC a more compact overall design
.

The on-board charger is a key component of new energy electric vehicles

With consumers' preference for higher-efficiency charging, manufacturers have gradually put forward demands such as 11kw or higher power OBCs to the market
.
Design integration and higher power trends make thermal management of OBCs increasingly important
.
In order to realize the thermal conductivity of these complex structures, a thermally conductive potting compound with higher thermal conductivity, high fluidity, high heat resistance and high elasticity is required to fill the gap between the components and the heat sink
.

In OBC, the potting compound conducts inductive heat

Based on the unique physical and chemical properties and excellent aging resistance of silicone, the most common thermal management solution is to use silicone potting compound with a certain thermal conductivity to encapsulate the electromagnetic induction components as a whole
.

However, with the improvement of thermal conductivity, silicone high thermal conductivity potting compounds also face some difficulties in application:

The potting compound has low fluidity and is difficult to realize the potting process: the thermal conductive potting compound with the same thermal conductivity and low fluidity cannot fill the small gaps between the components to the greatest extent, and it is difficult to realize the potting process
.
At the same time, the overall thermal resistance cannot be reduced, and it is difficult to achieve the optimal heat conduction effect
.
However, in formula design, it is difficult to take into account high thermal conductivity and fluidity at the same time
.

After high temperature curing, the stress of the potting compound is large, and the magnetic core is easy to crack: the potting compound material with large elastic modulus and linear thermal expansion coefficient will expand at high temperature and generate large internal stress
.
For the inductance components in OBC, the large internal stress will make the originally fragile magnetic core more easily cracked, resulting in a sharp drop in the detection value of the inductance and loss of its original function
.

High hardness and poor shock absorption: Silicone potting compounds with high thermal conductivity on the market usually have high hardness, generally at the Shore A level, and the material is hard
.
After curing, the silicone potting compound with lower hardness can eliminate most of the mechanical stress and play a shock absorption protection effect
.

Wacker Chem, the world's second largest silicone manufacturer, has developed a silicone 4W/mK high thermal conductivity potting compound with excellent performance and suitable for OBC, relying on its own advantages in the field of silicone technology
.

As an addition type two-component product, WACKER 4W/mK high thermal conductivity potting compound has excellent fluidity, low modulus and excellent thermal conductivity.
It is an ideal material for the potting protection of OBC power components.
It has the following characteristics Features and Benefits:

High thermal conductivity: The thermal conductivity is 4W/mK (ASTM D5470), which more effectively helps high-power OBC heat dissipation components to achieve thermal conductivity
.

Better spreading performance, self-leveling, excellent drilling and seam ability: while achieving high thermal conductivity, it can still maintain a good dynamic mixing viscosity (only 16Pa.
s), and the spreading diameter per unit volume is larger than that of competing products (Sampling 1ml)
.

Comparison of WACKER 4W/mK High Thermal Conductivity Potting Compound and Competitive Products

Adhesive: It can be tightly adsorbed on the surface of components
.
Especially after the drop test (GB/T 4857.
1), it can still be well adsorbed on the surface of the substrate to maintain the integrity of the potting parts
.

Coil potting remains intact after drop test

Low modulus, low stress, low hardness: WACKER 4W/mK high thermal conductivity potting compound does not release small molecules during the curing process of the addition reaction, and the material itself does not shrink
.
After curing, the modulus, linear thermal expansion coefficient and hardness are all low, and it has a very good protective effect on some stress-sensitive electronic components, such as magnetic cores in inductors
.

In addition to this 4W/mK high thermal conductivity silicone potting compound, WACKER has also developed different thermal conductivity of lower viscosity, 1.
2W/mK and 2.
0W/mK for the new energy electric vehicle electronic and electrical components market.
Coefficient of high-performance silicone thermally conductive encapsulants to provide customers with tailor-made solutions
.