Insufficient surface insulation margin is the primary
challenge
for a 10 kV plus high-voltage semiconductor module. Surface charge
accumulation and electric field distortion are the leading causes
of surface insulation failure. Power modules restrict leakage loss,
so only insulation dielectrics with low surface conductivity can be
used. However, low conductivity, accumulated charge dissipation, and
distorted electric field optimization have always been contradictory.
A potential barrier increase and electron affinity decrease are both
less coupled approaches with conductivity, which may have the potential
for reducing surface charge accumulation. Here, surface charge accumulation
inhibition and local electric field optimization were synchronously
realized by tailored coating deposition with colliding plasma jets.
This novelty approach leads to a finer interfacial modification of
the triple junction and its nearby interfaces. The high-barrier and
low-affinity coatings deposited by colliding plasma jets suppress
charge injection (electrode–polymer interface) and promote
charge dissipation (gas–polymer interface), respectively. At
the same time, the small-area semiconductor deposited at the triple
junction relieves the distortion of the electric field. In the end,
while maintaining a low leakage current, the surface flashover voltages
of polytetrafluoroethylene, polyimide, and epoxy packaging polymers
are significantly increased by 69.7, 43.2, and 39.6%, respectively.
Notably, the normalized leakage loss is less than 3/10,000 of the
commercially available SiC module, which vastly differs from the surface
insulation improvement strategy that blindly increases surface conductivity.
This tailored coating modification strategy provides a new idea for
dielectric research. It has reasonable practicability due to fast,
cheap, and environmentally friendly colliding plasma jets.