Thick Film Heaters vs. PTC Heaters: Principles, Differences, and Selection Guide

Thick Film Heaters vs. PTC Heaters:

Principles, Differences, and Selection Guide

In the thermal management of new energy vehicles, thick film heaters and PTC heaters are two mainstream electric heating solutions. They each have their advantages and disadvantages and are suitable for different scenarios. This article will comprehensively analyze their principles, differences, and selection recommendations.

1. What is a PTC Heater?

PTC is an abbreviation for Positive Temperature Coefficient. PTC heaters use barium titanate ceramic as the heating element. Its core characteristic is that resistance increases with temperature.

Working Principle

PTC heaters operate based on self-limiting temperature characteristics:

Low Temperature Start-up: At low temperatures, the PTC ceramic has low resistance, high current, and rapid heating.

Rapid Heating Up: A large amount of heat is generated, and the temperature rises rapidly.

Self-Limiting Temperature: When the temperature reaches the Curie point (approximately 80-150℃), the resistance increases sharply, the current automatically decreases, and the power decreases.

Steady State: The temperature automatically stabilizes near the Curie point, requiring no additional temperature control.

This characteristic makes PTC heaters inherently safe-they will not overheat or catch fire even when dry-burning.

Two Types of PTC Heaters

Air-type PTC: Directly heats air; hot air is blown out by a fan.

Simple structure, fast response: Mainly used for auxiliary cabin heating.

Water-type PTC: Heats coolant; heat is transferred through liquid circulation.

High power; can simultaneously heat the battery and cabin. The main heat source for mainstream new energy vehicles.

2. What is a Thick Film Heaters?

A thick film heater uses screen printing technology to print a resistance paste (such as rare earth materials like RuO₂) onto the surface of a metal substrate (stainless steel or ceramic). After high-temperature sintering, a micron-level heating circuit is formed.

Simply put, it doesn't involve winding resistance wires onto the substrate, but rather "printing" the heating circuit directly onto the heater surface, like a "printed circuit board."

Working Principle: The thick-film heater operates based on the Joule heating effect. The core process is as follows:

Electrification: Current flows through the printed thick-film resistive layer.

Heating: The resistive layer generates Joule heat (Q=I²Rt).

Conduction: Heat is rapidly conducted through the substrate layer to the liquid channel.

Heat Exchange: The flowing coolant absorbs heat, and its temperature rises.

Due to the extremely short distance between the resistive layer and the liquid channel (only the thickness of the substrate), the thermal resistance is minimal, resulting in an extremely fast response speed.

Key Characteristics

The thick-film heater does not have a built-in temperature limiting function. It requires a temperature sensor and control system to achieve closed-loop temperature control (typically with an accuracy of ±1℃). This makes its temperature control more precise, but the system is also relatively complex.

3. Recommended Scenarios for Using PTC Heaters

4. Recommended Scenarios for Using Thick Film Heaters