Heatsinks Difference between ATS-CPX030030015-142-C3-R0 and ATS-CPX030030015-142-C1-R0

The difference between heat sink part numbers ATS-CPX030030015-142-C1-R0 and ATS-CPX030030015-142-C3-R0 from
Advanced Thermal Solutions
is that the ATS-CPX030030015-142-C3-R0 has thermal interface material (TIM) included while ATS-CPX030030015-142-C1-R0 doesn’t have any TIM included.

Thermal Interface Material (TIM): Thermal interface materials are substances applied between two surfaces to enhance the thermal coupling between them. They are used to improve the heat transfer from one surface to another, typically from a heat-generating component (like a CPU or a power transistor) to a heat sink.

The TIM used in ATS-CPX030030015-142-C3-R0 is THERMATTACH T412 double-sided thermal interface tape.
A short description of THERMATTACH T412

Following properties can be looked into to get a better insight of thermal and electical properties of this TIM - T412:

Reference: Page 2 on the Datasheet

T412 is not intended to be electrically conductive as can be seen from the resistivity value which is 100 ohm-cm. And a resistivity of 100 ohm-cm typically indicates a material with high resistivity. Also, this material certainly would not be classified as one that is electrically insulating as there is no value of Voltage Breakdown on the datasheet, indicating as such.

Primary functionality of the T412 is its thermal performance.

Applicable Part Numbers
DK Part # Mfr Part #
ATS35925-ND ATS-CPX030030015-142-C1-R0
ATS35926-ND ATS-CPX030030015-142-C3-R0
ATS1524-ND ATS-CPX030030015-142-C2-R0